Review Article

Head and Neck Imaging: The Role of CT and MRI

Franz J. Wippold II, MD1–3*

High-resolution computed tomography (CT) and magneticresonance imaging (MRI) have become indispensable toolsfor the evaluation of conditions involving the head andneck. Complex anatomic structures and regions, such asthe orbit, skull base, paranasal sinuses, deep spaces of theneck, larynx, and lymph nodes, require that the radiologistbe familiar with the imaging modalities available and theirappropriate applications. The purpose of this article is toreview the techniques of CT and MRI and the roles they playin clinical practice, including head and neck disorders.

Key Words: magnetic imaging resonance; CT; head andneck imaging; imaging applications; imaging techniquesJ. Magn. Reson. Imaging 2007;25:453–465.© 2007 Wiley-Liss, Inc.

THE RAPIDLY EXPANDING INTEREST in the neck hasbeen largely fueled by the tremendous technical devel-opment and availability of cross-sectional imaging, andby the appreciation of these advancements by our clin-ical colleagues. High-resolution rapid computed tomog-raphy (CT) and magnetic resonance imaging (MRI) havelong since proven themselves sensitive and reliable inappropriate applications (1,2). Indeed, imaging has be-come an indispensable tool in the characterization andstaging of conditions involving the head and neck, andclinicians have come to incorporate imaging data withphysical examinations and endoscopy. CT and MRI notonly provide essential information about the deep ex-tension of clinically detected masses, they can also de-lineate additional clinically unsuspected lesions. Theexcellent tissue characterization of MR scans can lead

to an accurate diagnosis of many benign processes aswell. A complete study of head and neck imaging isbeyond the scope of this article; however, a review ofsome of the applications of CT and MRI may be helpful.

KEY CONCEPTS

Several key concepts must be applied when consideringcross-sectional imaging in the evaluation of head andneck lesions. First of all, imaging is a tool that supple-ments and complements the physical examination.Cross-sectional imaging is not a “stand-alone” proce-dure. Second, CT and MRI emphasize anatomy and thechanges in anatomy that occur with pathology. There-fore, knowledge of head and neck anatomy is crucial forthe accurate interpretation of images. Third, CT andMRI complement each other. Certain processes are bet-ter studied with one method than the other, and thevarious applications, strengths, and weaknesses ofeach modality should be carefully considered. Fourth,“context is king.” The interpretation of imaging studiesshould take into account the patient’s history, physicalfindings, comorbidities, and previous procedures thatmay influence the structures visualized. Comparisonfilms and previous imaging reports are also extremelyuseful and enable the imager to understand the clinicalissues that prompted the scan request. Of course, oldreports may be inaccurate and the radiologist shouldcarefully verify the source of information.

TECHNIQUES

CT

Standard Spiral CT

CT scanning of the head and neck should be tailored forthe anatomic region under consideration. A digital lat-eral scout radiograph may assist in planning the scanranges. Spiral (helical) CT scanning is rapidly replacingconventional dynamic CT (slice-by-slice acquisition) inmost medical centers (3). Spiral CT, which involves thecontinuous rotation of the x-ray tube and detector rowas the patient translates through the scanning gantry,permits rapid scanning of large volumes of tissues dur-ing quiet respiration, usually reduces the amount ofneeded intravenous contrast material, eliminates muchof the motion artifact seen with slower scans, and al-lows multiplanar and three-dimensional (3D) recon-structions (4–6). Moreover, multirow detector technol-ogy, which entails rotating the x-ray tube while

1Mallinckrodt Institute of Radiology, Washington University School ofMedicine, St. Louis, Missouri, USA.2Department of Radiology, Barnes-Jewish Hospital South, St. Louis,Missouri, USA.3Department of Radiology/Nuclear Medicine, F. Edward Hebert Schoolof Medicine, Uniformed Services University of the Health Sciences,Bethesda, Maryland, USA.Presented at the 13th Annual Meeting of ISMRM, Miami Beach, FL,USA, 2005.The opinions and assertions contained herein are the private views ofthe author and are not to be construed as official or as reflecting theviews of the United States Department of Defense.*Address reprint requests to: F.J.W., Neuroradiology Section, Mallinck-rodt Institute of Radiology, Washington University Medical Center, 510South Kingshighway Blvd., St. Louis, MO 63110.E-mail: wippoldf@wustl.eduReceived February 21, 2006; Accepted September 28, 2006.DOI 10.1002/jmri.20838Published online 5 February 2007 in Wiley InterScience (www.interscience.wiley.com).

JOURNAL OF MAGNETIC RESONANCE IMAGING 25:453–465 (2007)

© 2007 Wiley-Liss, Inc. 453

simultaneously employing multiple parallel detector ar-rays rather than a single detector row, has further ad-vanced spiral CT by reducing scan time and greatlyincreasing anatomic coverage. Debilitated, elderly, orarthritic patients may require scanning in the supineposition; however, reformatted coronal images are usu-ally easily derived from the axially acquired data. Withthe widespread application of spiral technology andfilmless picture archiving and communications sys-tems (PACS), reformatted coronal and sagittal imagesmay be obtained at the workstation, obviating the needto scan the patient in multiple planes.

General surveys typically cover the base of the skullto the clavicles with 4- or 5-mm-thick slices. The use ofintravenous contrast is recommended. For special re-gions of interest (ROIs), patients may be scanned withadditionally acquired 2-mm slices and a higher zoomfactor, or, with newer scanners, the same informationcan be obtained using reconstructed spiral data. Inpatients without significant dental restorations, scan-ning can usually be accomplished in a single range withslices parallel to the laryngeal ventricle. In patients withnumerous dental restorations, scan slices should beangled to avoid the teeth.

CT Angiography (CTA)

CTA is now challenging catheter angiography as theprimary method for assessing the vessels of the neck. Inaddition to evaluating the carotid arteries for evidenceof atherosclerotic disease, CTA can effectively detectarterial dissection in trauma patients. Primary arterialdisease, such as fibromuscular dysplasia, is also welldemonstrated. Evaluation of vascular encasement bytumors is another application. Scanning protocols vary;however, thin-slice spiral data (e.g., 1-mm collimationand table speed of 2 mm/second) during a contrastbolus usually provide excellent images. Images derivedfrom maximum intensity projection (MIP) and shadedsurface display techniques can then be examined at aworkstation. The advantages of CTA include its rapiddata acquisition and relative noninvasiveness—proper-ties that are especially important for the critically illpatient. Moreover, patients with cardiac pacemakersand ferromagnetic intracranial aneurysm clips, whichare contraindications to MR angiography (MRA), canundergo CTA. The drawbacks of CTA include venouscontamination due to ill-timed contrast boluses, physi-cian time-intensive data manipulation at a workstation,artifacts due to metallic foreign bodies, and potentiallyconfusing information caused by heavy mural calcifica-tion and adjacent bone.

Additional Techniques

Additional CT applications may prove useful. PerfusionCT (CTP), for example, is showing promise for evaluat-ing masses by measuring the mean transit time, bloodflow, and blood volume in benign neck lesions in com-parison with malignant lesions (7). This applicationcould potentially overcome some of the limitations ofother techniques, such as positron emission tomogra-phy (PET). A drawback of CTP, however, is image deg-

radation due to laryngeal motion or a poor contrastbolus.

Three-dimensional (3D) CT techniques may be help-ful for radiotherapy planning. This technique can beused to design radiotherapy beam trajectories and thuslimit extraneous collateral radiation to other organs,such as the salivary glands (8). CT is also useful forguiding percutaneous biopsies (9).

PET, which is regarded as a functional modality, de-tects lesions by imaging the uptake of the intravenouslyinjected radioactive glucose analog 2-[18F]-fluoro-2-de-oxy-D-glucose (FDG) in metabolically active tumors.Combined PET/CT superimposes the functional PETdata on nearly simultaneously acquired anatomic CTdata. By merging the excellent sensitivity of PET withthe spatial resolution of CT, one can potentially improvetumor localization, especially in patients who have un-dergone therapy. Drawbacks include technical consid-erations, such as the quality of the CT scans, misregis-tration artifacts due to patient motion, and potentiallyimprecise measurements of the radioactivity concen-tration on CT attenuation-corrected PET scans.

MRI

Standard MRI

MRI of the neck should be tailored for the anatomicregion and process under evaluation. A standard headcoil usually suffices for relatively localized examina-tions of the suprahyoid region and base of the skull. Theinfrahyoid neck requires a neck coil. Surface coils mayimprove the signal-to-noise ratio (SNR) by almost 50%compared to standard head coils; however, anatomiccoverage may be limited. Axial, coronal, and sagittalsequences are essential. Unenhanced axial T1-weighted images display anatomic relationships andcan detect lesions (e.g., lymph node lesions) embeddedwithin fat. T1-weighted coronal images can define thefalse vocal cords, true vocal cords, laryngeal ventricle,and the floor of mouth (10,11). T1-weighted sagittalimages provide helpful information about the pre-epi-glottic space and nasopharynx. T2-weighted transaxialimages characterize tissue, detect tumor within mus-cle, demonstrate cysts, and assist differentiation ofpost-therapy fibrosis from recurrent tumor (12). Fastspin-echo (FSE) T2-weighted imaging has the addedadvantage of a relatively short acquisition time (13,14).Gradient moment nulling, flow compensation, cardiacgating, and presaturation pulses minimize motion arti-facts. Phase and coding gradients are best oriented inthe anterior-posterior direction to further reduce dis-tracting artifacts (10).

Gadolinium (Gd)-enhanced images improve delinea-tion of margins in many lesions (15,16). Fat-suppres-sion techniques, such as short tau inversion recovery(STIR) and frequency-selected fat suppression, may im-prove the conspicuity of soft-tissue lesions embedded infatty tissue by selectively diminishing the hyperinten-sity of fat on T1-weighted images (15–17). Field inho-mogeneity and artifact may partially diminish the po-tential advantages of this technique. Moreover, thenormal enhancement of the aerodigestive mucosa mayconceal small mucosal tumors.

454 Wippold

Additional Techniques

Additional MR techniques may supplement standardprotocols. For example, the magnetization transfer (MT)technique may be useful for differentiating enhancinglesions from background tissue and defining poorly en-hancing lesions (18–20). This technique relies on thetransfer of magnetization between restricted protonsassociated with macromolecules and free protons ofwater to improve the tissue contrast. MT has not en-joyed widespread application in head and neck imag-ing, however, partly because conventional imaging usu-ally provides sufficient delineation of most primarylesions and lymphadenopathy. Moreover, MT is associ-ated with longer examination times and higher specificabsorption rates (SARs) than conventional imaging. 3Dreconstruction algorithms permit the 3D depiction ofthe tumor volume embedded within the surroundingsoft tissues. 3D software and workstations with offlineprocessing may facilitate the conceptual transforma-tion of two-dimensional (2D) information into a 3D for-mat and allow the examiner to “dissect” the display to adesired tissue depth (20).

MR Spectroscopy (MRS)

MRS has been used to examine 31-phosphorus, 19-fluorine, and 13-carbon in tissues; however, most in-vestigations have focused on hydrogen (proton) spectra.Although intracranial applications of MRS have beensteadily increasing, applications in the extracranialhead and neck have been disappointing. First of all,MRS requires a homogeneous magnetic field. Suscep-tibility artifacts introduced by the paranasal sinuses,airway, and bone, and pulsation artifacts from the ca-rotid artery severely degrade data. Additionally, a largeamount of fat within the neck produces a lipid peak thatobscures the relatively small peaks of tumor markers,such as choline. Finally, MRS remains rather nonspe-cific. Because many potentially lethal head and necktumors begin as small nests of cells within the mucosa,the lack of sufficient spatial resolution by MRS severelylimits its application. Moreover, most head and necklesions begin as mucosal processes, and the mucosaabuts the airway, further contributing to inhomogene-ity and artifacts (21). Nevertheless, work continues andnewer techniques may eventually make MRS practicalfor head and neck applications (22).

Open-Bore and High-Field-Strength Magnets

Although open-bore magnets may be used for the obeseor claustrophobic patient, anatomic depiction of com-plex anatomy and disease processes may be disap-pointing. These units have been especially useful forbiopsies and innovative procedures such as photody-namic laser therapy (23,24).

Finally, the advent of clinically available 3T magnetscreates both opportunities and challenges for head andneck imaging. The exaggerated chemical shift poses thepotential of heightened artifacts in the fat-laced anat-omy of the neck; however, the improved signal andcontrast may be exploited for better images.

Comparison of CT and MRI

MRI provides anatomic information on the neck thatcompares favorably with CT in most cases; however, itssuperiority to CT has not been conclusively establishedin all applications (11,25–32). The use of the multirowdetector spiral technique has greatly enhanced the ap-plications of CT, especially for vascular imaging, whileadvanced sequences and coil design have also improvedMRI considerably over the past few years. Nevertheless,a distinct advantage of MRI is its superb soft-tissuecontrast and multiplanar display by which blood ves-sels, masses, and adjacent soft tissues are easily differ-entiated (33,34). MR scanning is especially helpful forpatients in whom the distinction between a mass andsurrounding soft-tissue structures on CT is poor. MRIcan usually define these lesions in three orthogonalplanes, without the need to reposition the patient. Al-though CT scanning and its anatomic display havebeen primarily limited to the transverse plane, volumescanning using multirow detector spiral technique pro-vides isotropic voxels and has significantly expandedthe flexibility of multiplanar reformatted CT imaging.MRI better displays the lower neck without the degra-dation from shoulder artifact that occurs with CT. Den-tal restorations and densely calcified or ossified carti-lages usually do not significantly degrade MR images.

Although they are better tolerated than older agents,the newly developed intravenously administered, non-ionic, iodinated contrast agents used in CT carry adefinite risk of adverse reactions, including anaphy-laxis, and may compromise marginal renal function(35). The noniodinated Gd compounds used in MRI aregenerally considered somewhat safer for individualswith impaired renal function or a history of reactions tocontrast material; however, contrast reactions do occureven in MR scanning, and one should always exercisecaution when administering contrast to any highly al-lergic patient (36).

With MRI, motion artifacts from breathing, carotidartery pulsations, and swallowing may degrade images(10,37,38). Moreover, many patients with neck pathol-ogy have comorbidities, such as chronic obstructivepulmonary disease (COPD), or difficulty in controllingsecretions, which may become issues during long ex-aminations (10). Spiral CT scans can be obtainedwithin minutes, which alleviates many of these prob-lems in sick patients (39). Patients with cardiac pace-makers and metallic cochlear implants are restrictedfrom the MR scanner because of the effect of the strongmagnetic field and radiofrequency (RF) on these devices(40). Strongly ferromagnetic cerebral aneurysm clipsand dorsal column stimulators may potentially dislodgeor malfunction (41). Iron debris within the eye maycause visual impairment when subjected to the mag-netic field (42). Dentures and dental amalgams maycreate artifacts, though generally they are not as image-degrading as those seen in CT scans. Open-magnetdesign and newer scanner geometry coupled with ap-propriate levels of sedation have largely eliminatedproblems posed by anxiety and claustrophobia.

CT and MRI in Head and Neck Imaging 455

APPROPRIATE APPLICATIONS

Orbit

MRI has become the modality of choice for evaluatingnontraumatic orbit pathology (Table 1). Superior soft-tissue contrast, multiplanar display, and fat-saturationenhancement techniques combine to produce a power-ful analytic tool, especially for defining mass lesions.Acute traumatic injury and some infections remainwithin the realm of CT imaging, primarily because of theavailability of scanners and the speed of scanning,which is advantageous for seriously ill patients. Smallcalcifications and densities produced by foreign bodiesand tumors, such as meningiomas, are also best de-tected with CT. For the orbit, axial scans without andwith the use of intravenous contrast material providean adequate baseline evaluation. Bone algorithm re-constructions are extremely useful in cases of trauma.Coronal images are also very useful, especially for eval-uating extraocular muscle caliber, optic nerves, para-nasal sinuses, and the cribriform plate.

An effective way to organize the anatomy and pathologyof the orbit is to divide this region into distinct compart-ments based on fascial layers that are easily defined withcross-sectional imaging. These regions often have distinctpathologic differential diagnoses. The compartment con-taining the globe itself is encased by Tenon’s capsule.Tenon’s capsule in turn separates the globe from extraoc-ular tissues. The myofascial sling invests the extraocularmuscle cone and separates the intraconal space, whichcontains fat and the optic nerve, from the extraconalspace. The periorbital fascia separates the intraorbitalextraconal space from extraorbital anatomy.

The globe consists of the fluid-filled anterior cham-ber, posterior chamber, and vitreous body. Because ofthe superb tissue differentiation capabilities of MRscanning, hemorrhage and masses can be easily de-tected and characterized when they are sufficientlylarge. Smaller lesions are best clinically evaluated withfundoscopy; however, MR scanning may provide valu-able information about scleral penetration. Fluid collec-tions, such as blood within Tenon’s space, are alsoeasily diagnosed with MRI. Fat-saturated fluid-attenu-ated inversion recovery (FLAIR) imaging and diffusion-weighted imaging (DWI) may be useful for followingtherapeutic response to inflammation (43). Choroidal,hyaloid, and retinal detachments may be differentiatedwith MRI.

The intraconal space may be further divided into theoptic nerve and intraconal fat. The optic nerve is beststudied with MR scanning in the coronal plane supple-mented with axial and sagittal plane information.FLAIR imaging may detect hyperintensity in variousconditions, such as optic neuritis, and the addition ofT1-weighted Gd-enhanced sequences, especially whencoupled with a fat-saturation technique, may defineactive inflammation or tumors (Fig. 1). Increases in theapparent diffusion coefficient (ADC) in DWI have beenobserved in chronic, postinflammatory optic nerve le-sions in demyelination (44).

The fat within the intraconal space provides excellentinherent signal contrast properties for detectingmasses, such as hemangiomas and schwannomas.Care must be taken when interpreting fat-saturationsequences because of the potentially misleading effectof field inhomogeneity. The imager should always re-view non-fat-suppressed T1-weighted and T2-weightedimages to verify inflammatory infiltrates within thisspace. Advances in phase-corrected algorithms forthree-point Dixon (3PD) imaging, in which pure water,pure fat, and water-plus-fat online image reconstruc-tions are produced, promise to increase the SNR andcontrast-to-noise ratio (CNR) (45).

The extraocular muscle cone is nicely silhouetted byintraconal fat. MRI outlines enlarged muscles and thetendonous insertions. Coronal images are excellent forverifying muscle size. Reconstructions derived frommagnetization-prepared rapid-gradient-echo (MP-RAGE) images can be used to correct difficulties inpatient positioning and can facilitate complex multipla-nar demonstrations of difficult pathology. Because ofthe lack of signal intensity from cortical bone, the opticnerve within the optic canal can be well visualized. Withthe use of Gd enhancement, subtle meningeal pathol-ogy can be detected. Paranasal sinus pathology, whichcan extend into the extraconal space, is also well char-acterized with MRI. The use of signal intensity on T2-weighted images and enhancement properties can as-sist in differentiating tumor spread from inflammatorydisease.

Skull Base

Most studies divide the skull base into anterior, central,and posterior regions. Conceptually, the anterior skullbase is dominated by the ethmoid bone, the central

Table 1Indications for Imaging by Anatomic Region

Anatomic region CT MR

Orbit Trauma; acute infection Masses; complicated infection, i.e., intracranial involvementSkull base Trauma; conductive hearing loss;

acquired middle ear cholesteatoma;bone erosion

Masses (especially suspected intracranial or neckextension); neurosensory hearing loss; perineural spreadof tumor

Paranasal sinuses Trauma; infection Cephalocele; complicated infection; masses (especiallysuspected intracranial or orbit extension)

Deep spaces Acute infection; sialolithiasis Masses; perineural spread of tumorLarynx Trauma; masses (CT and MR imaging

complementary)Masses (CT and MR imaging complementary); posttherapy

evaluationLymph nodes Lymphadenopathy (CT and MR

imaging complementary)Lymphadenopathy (CT and MR imaging complementary)

456 Wippold

skull base is dominated by the sphenoid bone, and theposterior skull base is dominated by the occipital bone.Similarly, lesions can be grouped into those that origi-nate above the skull base and invade inferiorly, thosethat involve the bone itself, and those that begin inferiorto the skull base and invade superiorly (46,47).

MRI clearly excels in evaluating the skull base, espe-cially lesions with intracranial and neck soft-tissuecomponents (Table 1, Fig. 2). Although CT does providevaluable information about cortical bone itself, the sen-sitivity of contrast-enhanced MR scans combined withmultiplanar capabilities for detecting meningeal spreadand cranial nerve involvement clearly vaults MRI intothe dominant role. CT typically requires a bony algo-rithm for fine-bone detection, which further diminishesits value for evaluating the adjacent brain. For skull-base evaluations with CT, axial scans are typicallyused. The spiral technique provides zoomed 1-mmhigh-resolution axial slices that can then be reformat-ted in multiple planes with excellent spatial resolution.

Soft-tissue algorithms usually require somewhatthicker slices (e.g., 5 mm), and may be supplementedwith intravenous contrast material.

MRI, on the other hand, can fully evaluate the brain.The flow void of the carotid arteries also provides excel-lent inherent contrast with tumors that potentially en-case such vessels. High-resolution sequences, such as3D constructive interference in the steady state (CISS),give the appearance of a heavily T2-weighted sequenceand can be used to examine skull-base anatomy inregions such as the cavernous sinus (48).

The temporal bone can also be included in skull-basestudies. For conductive hearing loss, CT scanning re-mains the initial screening modality because of its ex-cellent depiction of the middle-ear ossicles and bonyanatomy (Fig. 3). The spiral technique with submillime-ter reconstruction yields detail never before experi-enced by imagers. Inflammatory temporal bone pathol-ogy is also best studied with CT. For neurosensoryhearing loss, however, MRI offers a variety of tech-niques to fully evaluate the internal auditory canal andcerebellopontine angle. Traditional high-resolution,thin-slice, contrast scanning can detect enhancingschwannomas within the internal auditory canal (Fig.4). High-resolution T2-weighted images using 3D fastrecovery FSE (FRFSE) and CISS imaging can dissectindividual nerves without the use of contrast, and yieldimpressive 3D renderings (49,50) (Fig. 5). Diagnosessuch as cochlear nerve atrophy, cochlear nerve aplasia,and endolymphatic sac lesions are now within thereach of imaging. DWI has also been proposed for dif-ferentiation of recurrent cholesteatoma from granula-tion tissue after mastoidectomy (51).

MRI has also made it possible to confidently diagno-sis of perineural spread of malignancies (52–55). A di-agnosis of perineural spread of skull-base lesions iscritically important for treatment planning, and indi-cates far more extensive disease than may be clinicallydetected by even the most astute surgeons. CT usuallyonly indirectly infers perineural spread by demonstrat-ing enlargement of the bony foramina. Fat-saturation

Figure 1. Retrobulbar neuritis in a patient with multiple scle-rosis. a: Coronal enhanced T1-weighted MR image with fatsaturation demonstrating an enlarged enhancing right opticnerve. b: Corresponding axial FLAIR T2-weighted MR imageshowing the hyperintense periventricular demyelinatingplaques.

Figure 2. Meningioma arising in the anterior skull base. Sag-ittal enhanced T1-weighted image demonstrates a large, mark-edly enhancing, extra-axial soft-tissue mass within the frontallobes. The tumor has extended below the cribriform plate intothe ethmoid paranasal sinus, and has also invaded the sellaturcica perched above the pituitary gland.

CT and MRI in Head and Neck Imaging 457

Gd-enhanced MR scans are often capable of detectingsubtle tumor tracking along the Vth and VIIth cranialnerves, as well as other nerves that travel through themany foramina of the skull base, before the lesionshave grown sufficiently large to affect the surroundingbone (Fig. 6).

Paranasal Sinuses

CT remains the acknowledged modality of choice for theroutine evaluation of paranasal sinus inflammatorydisease because of its excellent depiction of bone (56)(Table 1, Fig. 7). Direct coronal scanning using a bonealgorithm and 1- to 3-mm-thick slices are recom-

mended for the paranasal sinuses because of the supe-rior portrayal of the osteomeatal units in this plane.MRI can complement CT for diagnostically challengingcases. For example, MRI may reveal a cephalocele filledwith characteristic brain and cerebrospinal fluid sig-nals eroding the cribriform plate, whereas CT may notbe able to differentiate cephalocele from other causes ofsoft-tissue density, such as nasal polyp or inflamma-tory disease (57). Additionally, MRI provides importantsignal information that may differentiate tumor frominflammatory disease. As a general rule, most inflam-matory diseases have hyperintense signal characteris-tics on T2-weighted images. As secretions inspissate,signal may change on both T1- and T2-weighted im-ages. Careful clinical correlation is therefore essentialin such cases (58). Because mucosal secretions areavascular, they will typically fail to enhance after theadministration of Gd. The inflamed mucosa will en-hance in a ring configuration that lines the sinus cavity.Tumors, on the other hand, usually display intermedi-ate signal intensity on T2-weighted images and homo-geneously enhance (Fig. 8). Exceptions to these rules

Figure 3. Superior semicircular canal dehiscence. Reformat-ted axial CT images demonstrate lack of bony covering of thesuperior semicircular canal (arrows) consistent with dehis-cence. CT scanning is the preferred method for evaluatingconductive hearing loss and the fine bony anatomy of thetemporal bone.

Figure 4. Vestibular schwannoma. Coronal enhanced T1-weighted MR image shows an enhancing right intracanalicularmass (arrowhead). MRI is preferred for evaluation of neurosen-sory hearing loss.

Figure 5. Normal cochlea. Volume-rendered 3D oblique viewsof the cochlea are based on 3D T2-weighted images acquired at3T. (Case courtesy of Benjamin C.P. Lee.)

Figure 6. Extensive skull-base squamous cell carcinoma withperineural spread of tumor involving the trigeminal and facialnerves. Axial enhanced T1-weighted image demonstrates en-hancement of the left facial nerve. Note the atrophy of the leftmuscles of mastication.

458 Wippold

include tumors in which necrotic foci fail to enhance,and adenoid cystic carcinomas in which the oftenmarkedly hyperintense signal on T2-weighted imagesmay mimic inflammatory disease.

MRI is also ideally suited for evaluating anterior cra-nial fossa involvement of paranasal sinus tumors thathave perforated the cribriform plate (Figs. 2 and 8).Subtle tell-tale meningeal enhancement may be easilydetected by coronal sequences. Orbital involvement byparanasal sinus tumors is also well evaluated withcoronal and axial MRI using Gd intravenous contrastand fat-saturation techniques.

Deep Spaces of the Neck

With the advent of cross-sectional imaging, the tradi-tional cervical triangle method of organizing the anat-omy of the neck has been largely replaced by a systemthat defines neck spaces according to the cervical fas-cial planes. The differential diagnoses of diseases of theneck are related to the space of origin, and thereforethis system of relying on the fascial planes is ideallysuited to both imaging and clinical management ofhead and neck patients. The cervical spaces of the su-prahyoid and infrahyoid neck include the sublingualspace, submandibular space, buccal space, parotidspace, parapharyngeal space, carotid space, masticatorspace, pharyngeal mucosal space, visceral space, ret-ropharyngeal space, posterior cervical space, and peri-vertebral space.

The paired sublingual spaces are located in the floorof the mouth and are defined by the mandible anteriorlyand laterally, the hyoid bone posteriorly, the oral mu-cosa superiorly, and the mylohyoid muscle inferiorly(59). Contained within this space are the paired sublin-gual salivary glands; the deep lobes of the submandib-ular salivary glands; submandibular ducts; the genio-glossus, geniohyoid, hyoglossus, and styloglossusmuscles; the lingual arteries; the lingual branches ofthe third division of the Vth cranial nerve; the glosso-pharyngeal and hypoglossal nerves; and fat (60). Typi-cal lesions include carcinomas extending from the floorof the mouth and the tongue, ranulas, dermoids andepidermoids, hemangiomas and lymphangiomas, lin-gual thyroid glands and thyroglossal duct cysts, ab-scesses, enlarged lymph nodes, calculi within the sub-mandibular duct, and schwannomas (60,61). MRI, withits multiplanar capabilities and fat-saturation tech-niques, is ideally suited for studying this space becauseof the lack of significant artifacts from dental restora-tions and beam-hardening. CT remains the study ofchoice for evaluating calculi (Table 1).

The submandibular space is posterolateral to thesublingual space and contains the superficial lobe ofthe submandibular salivary gland and lymph nodes(59). Lesions within this space include cystic hygromas,branchial cleft cysts, dermoids, epidermoids, thyroglos-sal duct cysts, abscesses, calculi from the submandib-

Figure 7. Sinonasal polyposis. Coronal CT scan showsa soft-tissue mass filling the upper portion of the nasalcavity and ethmoid sinuses with bilateral extensionthrough the osteomeatal units into the medial portionsof the maxillary sinuses. Minimal mucosal thickening isidentified in the inferior portions of both maxillary si-nuses. The left frontal sinus is also opacified.

Figure 8. Squamous cell carcinoma of the ethmoid paranasalsinus. Coronal enhanced T1-weighted MR image with fat sat-uration demonstrates a homeogeneously enhancing left eth-moid soft-tissue mass. The mass extends inferiorly into thesuperior nasal cavity and invades the left maxillary sinusthrough the osteomeatal unit. The mass has perforated thecribriform plate and invaded the anterior cranial fossa. The leftorbit has also been invaded. The tumor has extended acrossthe midline to involve the right ethmoid sinus.

CT and MRI in Head and Neck Imaging 459

ular glands, and salivary gland masses. Because of thehigh fat content of this space and the limited variety ofstructures found within it, both MRI and CT are rou-tinely used for evaluations. MRI is advantageous forcharacterizing tissue in neoplasms, and CT is preferredfor patients with acute infections.

The buccal space is a small region anterior to themasseter and lateral to the buccinator muscle. Patho-logic conditions that occur in this space include infec-tion, deeply invasive skin cancers, minor salivary glandtumors, and facial lymphadenopathy (62–64). MRI bestevaluates this space.

The parotid space is located posterior to the massetermuscle and contains the parotid gland, Stenson’s duct,the facial nerve, and intraparotid lymph nodes andblood vessels (59,65). Salivary lesions, such as pleo-morphic adenoma, mucoepidermoid carcinoma, andadenoid cystic carcinoma, make up the vast majority oflesions within this space. Lymphadenopathy and he-mangiomata may also be seen. Because of the subtlewater and fat contrast within the parotid gland and thesurrounding tissues, MRI has become the method ofchoice for evaluating masses (66,67) (Fig. 9). MRI is alsoexcellent for patients with suspected autoimmune dis-ease, such as Sjogren’s syndrome, and some studieshave examined the use of MR sialography in such con-ditions (68–70). CT is reserved for stone disease andsome acute infections.

The parapharyngeal space extends from the skullbase to the hyoid bone and is posteromedial to themasticator space. The parapharyngeal space is subdi-vided into prestyloid and poststyloid compartments.The prestyloid compartment contains branches of theinternal maxillary and ascending pharyngeal arteries,nerves, fat, salivary rests, and minor salivary glands(62). Primary lesions of the prestyloid compartment areoften salivary in origin, such as pleomorphic adenomas,but other lesions, such as carcinomas invading fromadjacent spaces, lipomas, and schwannomas, also oc-cur with relative frequency (71). The poststyloid com-partment (also known as the carotid space) containsthe carotid artery, internal jugular vein, glossopharyn-

geal nerve, vagus nerve, spinal accessory nerve, hypo-glossal nerve, sympathetic chain, and internal jugularlymph nodes (71,72). Lesions occurring in this spacearise from the tissues found within this region andnotably include glomus tumors and schwannomas (73).MRI is the preferred method for evaluating the parapha-ryngeal space.

The masticator space is formed by the splitting of thesuperficial layer of the deep cervical fascia, and in-cludes the mandible, the muscles of mastication, andthe mandibular division of the trigeminal nerve(59,65,71,74). Lesions derived from these tissues in-clude nerve sheath tumors, mandibular and soft-tissuesarcomas, dental tumors, cysts and abscesses, osteo-myelitis, and lipomas (75,76). Vascular lesions, such ashemangiomas, lymphangiomas, and, rarely, pseudoan-eurysms, may also occur. In children, rhabdomyosar-coma also may present in the masticator space. Theforamen ovale at the skull base forms the “chimney ofthe masticator space” and is a frequent conduit of le-sions traversing the masticator space and middle cra-nial fossa. Although CT demonstrates the cortex of themandible in acutely traumatized or infected patients,MRI is the modality of choice for neoplasms. Multipla-nar acquisitions and Gd contrast-enhanced imagesbest demonstrate perineural spread involving the tri-geminal nerve.

The pharyngeal mucosal space includes the mucosalsurfaces and immediate submucosa of the nasophar-ynx and oropharynx. The oral cavity and suprahyoidportion of the hypopharynx can also be included in thisspace (77). Mucosa, lymphoid tissue, minor salivaryglands, pharyngeal constrictor muscles, and the sal-pingopharyngeus muscle are contained in this space(77,78). Predictably, the most common malignant le-sion of the pharyngeal mucosal space is carcinoma,although benign lesions, such as salivary tumors, mayalso occur. Lesions may be superficial, in which caseMR scanning may yield false-negative results, or deeplyinvasive, in which case MRI can be very helpful. Al-though MRI is generally considered the best choice forevaluating mandibular involvement with oral cavitycarcinoma, chemical shift artifact and concomitant in-flammation may diminish its specificity (79,80). Meth-ods of tumor volume assessment have also receivedrecent attention, especially with oncology therapy pro-tocols requiring objective measurements of therapy re-sponse. Both CT and MR scans have been used in suchdeterminations, although validation continues to be anissue (81).

The visceral space contains the larynx and hypophar-ynx, the thyroid and parathyroid glands, the tracheaand esophagus, peritracheal lymph nodes, and the re-current laryngeal nerves (65). Lesions typically reflectthese tissues and include squamous cell carcinomas,thyroid and parathyroid adenomas and carcinomas,and schwannomas.

The retropharyngeal space lies posterior to the vis-ceral space and extends from the base of the skull to themediastinum. This space serves as a conduit for thespread of neck pathology into the chest (82,83). Lymphnodes occupy the suprahyoid portion of this space andmay enlarge in oropharyngeal infection and malignan-

Figure 9. Hemangioma of the left parotid gland. A large hy-perintense intraparotid hemangioma is identified on axial T2-weighted MR image. The lesion invades the masticator spaceanteriorly and the parapharyngeal space medially.

460 Wippold

cies. CT tends to serve as the first line of diagnosis,especially in infection; however, it is difficult to differ-entiate between retropharyngeal abscess and adenitisbecause both processes cause hypodense regionswithin the inflammatory mass. MRI is excellent for de-tecting metastatic retropharyngeal lymph nodes (84)(Fig. 10).

The posterior cervical space abuts the carotid spaceposterolaterally and is sandwiched by the sternocleido-mastoid muscle anterolaterally and the paraspinalmuscles posteromedially (59,85). The primary compo-nents of this space are fat, the spinal accessory anddorsal scapular nerves, and the spinal accessory lymphnodes of the deep cervical chain. Among the lesionsmost commonly seen in this space is lymphadenopathyfrom metastatic squamous cell carcinoma, with pri-mary sites in the pharyngeal mucosal space and lym-phoma. Lipomas, sarcomas, cystic hygromas, andbranchial cleft cysts are also seen in this space. Be-cause fat, the major component of this space, providesnaturally occurring tissue contrast, both CT and MRIperform well. Large extracapsular nodal masses tend toblend with the muscle boundaries of this space, how-ever, and MRI is superior to CT in this application.

The perivertebral space is formed by the deep cervicalfascia. An anterior compartment envelops the vertebralbodies and spinal cord, the vertebral arteries, phrenicnerve, and perivertebral and scalene muscles. A poste-rior compartment contains the posterior vertebral ele-ments and the paraspinous muscles (59,65,83). Exam-ples of pathology include vertebral osteomyelitis,necrotizing fasciitis and metastases, nerve sheath tu-mors (e.g., plexiform neurofibromas), and rare lesions(e.g., chordoma). MRI is preferred for depicting soft-

tissue lesions, although CT remains very useful for pre-cisely identifying details of bone destruction.

Larynx

The larynx is usually anatomically divided into the su-praglottic, glottic, and subglottic (infraglottic) regions.The supraglottic division is defined as the portion of thelarynx that extends from the superior-most tip of theepiglottis to a transverse plane through the laryngealventricle. The glottis extends from this transverse planeto 1 cm inferiorly and includes the true vocal cords. Thesubglottic region extends from the inferior-most planeof the true cords to the inferior portion of the cricoidcartilage.

The vast majority of lesions discovered in patientsreferred for imaging of the larynx are squamous cellcarcinomas, although benign lesions, such as laryngo-celes, do occasionally appear (86,87). Small benign en-tities, such as polyps, are usually easily diagnosed inthe clinician’s office and typically are not scanned. Mul-tiplanar MRI is especially well suited for analysis oflaryngeal lesions (88). Soft-tissue contrast aids in theearly detection of spread of tumor into paraglottic andpreepiglottic fat. These areas are not easily evaluated byclinical endoscopy, and have a negative predictive valuefor survival. The use of Gd intravenous contrast mate-rial further refines detection (89). Cartilage invasion,carotid encasement, and transglottic involvement viasubmucosal spread are also well studied with MR scan-ning (27,88,90). Because spiral CT is readily availableand scanning times are extremely rapid, CT remains avaluable and frequently used screening modality for thelarynx (Table 1, Fig. 11). CT is also attractive for pa-tients undergoing imaging of the larynx, because manyof these patients have COPD and/or difficulty with se-cretions.

Although the value of MRI for imaging the post-treat-ment larynx exceeds that of CT, false-negative or false-

Figure 10. Adenoid cystic carcinoma. Axial T1-weighted en-hanced MR image demonstrates a large hyperintense adenoidcystic carcinoma of the nasal cavity invading the left maxillarysinus, left masticator space, left parapharyngeal space, poste-rior right maxillary sinus, right masticator space, and rightparapharyngeal space. Bilateral retropharyngeal node metas-tases are evident.

Figure 11. Supraglottic squamous cell carcinoma of the lar-ynx. Axial contrast-enhanced CT scan reveals a thickenedepiglottis that is more prominent on the right. The surround-ing paraglottic fat is not involved. A necrotic right jugularchain lymph node is also noted.

CT and MRI in Head and Neck Imaging 461

positive interpretations may still result. PET, especiallywhen coupled with CT, is a useful adjunct.

Lymph Nodes

Cervical lymphatics are critical conduits that drain theskin and mucosal surfaces of the head and neck. Nearly40% of all lymph nodes in the body are located abovethe clavicles; only the orbit and cervical muscles do nothave direct lymphatic connections. Lymph nodes areusually embedded within the fat planes that surroundthe vessels and separate major cervical muscles. There-fore, the fat of the neck provides an excellent naturalcontrast with the nodes on T1-weighted MR images.Lymph nodes are divided into 10 major groups (59,91).These groups are named for the structures in proximityto nodal location. Six groups (the occipital, mastoid,parotid, submandibular, facial, and submental groups)form a sentinel ring at the skull base. Additionally, asublingual group lies deep in the floor of the mouth,and the retropharyngeal group is embedded within theretropharyngeal space. These sentinel groups draininto paired anterior and lateral cervical chains to ex-tend from the skull base to the clavicles. Of thesegroups, the submental, submandibular, retropharyn-geal, and lateral cervical chains play especially impor-tant roles in the spread of head and neck disease.

The lateral cervical chain is subdivided into the su-perficial and deep lateral cervical lymph nodes. Thesuperficial group follows the course of the external jug-ular vein. It is usually palpable, and therefore is notusually examined by imaging. The important deepgroup is further divided into the spinal accessory,transverse cervical, and internal jugular groups. Thespinal accessory nodes are found within the fat of theposterior cervical space adjacent to the spinal acces-sory nerve, and the internal jugular group tracks alongthe internal jugular vein.

The American Joint Committee on Cancer (AJCC) andthe American Academy of Otolaryngology—Head andNeck Surgery divide these 10 lymph node chains into aseries of levels that have prognostic importance (92,93).Briefly, level 1 consists of the submental and subman-dibular nodes. Level 2 includes the internal jugularnodes extending from the base of the skull to the carotidbifurcation (hyoid bone). Normal nodes in levels 1 and 2may measure up to 1.5 cm in diameter. Level 3 corre-sponds to the internal jugular nodes from the carotidbifurcation to the omohyoid muscle (cricoid cartilage).Level 4 refers to all nodes in the internal jugular groupfrom the omohyoid muscle to the clavicle. Level 5 con-sists of the spinal accessory and transverse cervicalnodes that occupy the posterior cervical triangle. Level6 contains the pretracheal, prelaryngeal, and paratra-cheal nodes. Finally, level 7 includes the nodes in thetracheoesophageal groove and upper mediastinum.Nodes from level 3 to level 7 should not exceed a max-imum diameter of 1 cm.

Nodal enlargement beyond the acknowledged maxi-mum diameter is one of the most common signs ofabnormality, although false-negative and false-positiveresults may occur. Necrosis also indicates abnormality.Clusters of three or more contiguous ill-defined nodes

within the same level ranging from 8 mm to 15 mm insize may also be considered abnormal. Although nodalshape is no longer thought to be a reliable sign fordifferentiating normal from pathologic nodes, roundnodes tend to be neoplastic, whereas elliptical or bean-shaped nodes are generally normal or hyperplastic(92,94). Despite these criteria, a large number of false-negative and false-positive interpretations may result.Moreover, recognition of nodal abnormality on cross-sectional imaging does not necessarily guarantee iden-tification of etiology. Extensive adjacent soft-tissuestranding coupled with a rapidly developing history offever and painful adenopathy, implies inflammation,whereas a subacute or chronic clinical course, a slowlygrowing relatively painless mass that is hard to palpa-tion, and nodal necrosis on imaging suggest neoplasm.Lymphadenopathy arising from squamous cell carci-noma often displays necrosis, whereas nodes associ-ated with lymphoma typically do not. The use of ADCvalues and dynamic contrast-enhanced (DCE) MRscans may further assist in determining etiology (95–97).

The imaging community is divided in its recommen-dations regarding an appropriate modality for evaluat-ing lymphadenopathy (26,32,98). CT remains very pop-ular because of it availability, speed, and excellentspatial resolution. Lymph nodes are usually embeddedwithin fat, and fat is well portrayed by CT (Figs. 11 and12). Alternatively, MRI has superior soft-tissue contrastand multiplanar capabilities (Table 1, Fig. 10). In anattempt to further refine the diagnostic power of MRI,dextran-coated ultrasmall superparamagnetic iron ox-ide (USPIO) has been developed as a lymph node con-trast agent based on the siderocytic capabilities of nor-mal nodes compared with pathologic nodes. However,technical factors, such as 24- to 36-hour imagingtimes, have limited its widespread application (99,100).

CONCLUSIONS

Cross-sectional imaging has revolutionized the practiceof head and neck radiology, as well as the clinical spe-cialty of otolaryngology/head and neck surgery. The

Figure 12. Metastatic lymphadenopathy. Axial contrast-en-hanced CT scan shows large bilateral necrotic jugular chainlymph nodes spread from a laryngeal primary site.

462 Wippold

complementary roles of CT and MRI offer powerful toolsfor the diagnosis and management of benign and ma-lignant conditions, provided that the radiologist under-stands the clinical issues regarding the patient and theanatomy under investigation. With the advent of 3Tmagnets and innovative pulse sequences and coils, thefield of head and neck imaging will continue to evolve inthe years to come.

REFERENCES

1. Gatenby RA, Mulhern Jr CB, Strawitz J, Moldofsky PJ. Compari-son of clinical and computed tomographic staging of head andneck tumors. AJNR Am J Neuroradiol 1985;6:399–401.

2. Stark DD, Moss AA, Gamsu G, Clark OH, Gooding GA, Webb WR.Magnetic resonance imaging of the neck. Part II: Pathologic find-ings. Radiology 1984;150:455–461.

3. Keberle M, Kenn W, Hahn D. Current concepts in imaging oflaryngeal and hypopharyngeal cancer. Eur Radiol 2002;12:1672–1683.

4. Spreer J, Krahe T, Jung G, Lackner K. Spiral versus conventionalCT in routine examinations of the neck. J Comput Assist Tomogr1995;19:905–910.

5. Mukherji SK, Castillo M, Huda W, et al. Comparison of dynamicand spiral CT for imaging the glottic larynx. J Comput AssistTomogr 1995;19:899–904.

6. Suojanen JN, Mukherji SK, Wippold FJ. Spiral CT of the larynx.AJNR Am J Neuroradiol 1994;15:1579–1582.

7. Rumboldt Z, Al-Okaili R, Deveikis JP. Perfusion CT for head andneck tumors: pilot study. AJNR Am J Neuroradiol 2005;26:1178–1185.

8. Emami B, Purdy JA, Simpson JR, Harms W, Gerber R, Wippold JF.3-D conformal radiotherapy in head and neck cancer. The Wash-ington University experience. Front Radiat Ther Oncol 1996;29:207–220.

9. Yousem DM, Sack MJ, Scanlan KA. Biopsy of parapharyngealspace lesions. Radiology 1994;193:619–622.

10. Hudgins PA, Gussack GS. MR imaging in the management ofextracranial malignant tumors of the head and neck. AJR Am JRoentgenol 1992;159:161–169.

11. Jabour BA, Lufkin RB, Hanafee WN. Magnetic resonance imagingof the larynx. Top Magn Reson Imaging 1990;2:60–68.

12. Glazer HS, Lee JK, Levitt RG, et al. Radiation fibrosis: differenti-ation from recurrent tumor by MR imaging. Radiology 1985;156:721–726.

13. Lewin JS, Curtin HD, Ross JS, Weissman JL, Obuchowski NA,Tkach JA. Fast spin-echo imaging of the neck: comparison withconventional spin-echo, utility of fat suppression, and evaluationof tissue contrast characteristics. AJNR Am J Neuroradiol 1994;15:1351–1357.

14. Yousem DM, Hurst RW. MR of cervical lymph nodes: comparisonof fast spin-echo and conventional spin-echo T2W scans. ClinRadiol 1994;49:670–675.

15. Hasso AN, Brown KD. Use of gadolinium chelates in MR imaging oflesions of the extracranial head and neck. J Magn Reson Imaging1993;3:247–263.

16. Vogl T, Dresel S, Juergens M, Assal J, Lissner J. MR imaging withGd-DTPA in lesions of the head and neck. J Otolaryngol 1993;22:220–230.

17. Barakos JA, Dillon WP, Chew WM. Orbit, skull base, and pharynx:contrast-enhanced fat suppression MR imaging. Radiology 1991;179:191–198.

18. Balaban RS, Ceckler TL. Magnetization transfer contrast in mag-netic resonance imaging. Magn Reson Q 1992;8:116–137.

19. Gillams AR, Fuleihan N, Grillone G, Carter AP. Magnetizationtransfer contrast MR in lesions of the head and neck. AJNR Am JNeuroradiol 1996;17:355–360.

20. Lofchy NM, Stevens JK, Brown DH. Three-dimensional imaging ofthe parapharyngeal space. Arch Otolaryngol Head Neck Surg1994;120:333–336.

21. Mukherji SK, Schiro S, Castillo M, Kwock L, Muller KE, Black-stock W. Proton MR spectroscopy of squamous cell carcinoma ofthe extracranial head and neck: in vitro and in vivo studies. AJNRAm J Neuroradiol 1997;18:1057–1072.

22. King AD, Yeung DKW, Ahuja AT, Leung SF, Tse GMK, van HasseltAC. In vivo proton MR spectroscopy of primary and nodal naso-pharyngeal carcinoma. AJNR Am J Neuroradiol 2004;25:484–490.

23. Jager HR, Taylor MN, Theodossy T, Hopper C. MR imaging-guided interstitial photodynamic laser therapy for advancedhead and neck tumors. AJNR Am J Neuroradiol 2005;26:1193–1200.

24. Lambre H, Anzai Y, Farahani K, Castro D, Lufkin RB. Interven-tional magnetic resonance imaging of the head and neck and newimaging techniques. Neuroimaging Clin N Am 1996;6:461–472.

25. Curtin HD. Imaging of the larynx: current concepts. Radiology1989;173:1–11.

26. Madison MT, Remley KB, Latchaw RE, Mitchell SL. Radiologicdiagnosis and staging of head and neck squamous cell carcinoma.Radiol Clin North Am 1994;32:163–181.

27. van den Brekel MW, Castelijns JA, Snow GB. The role of modernimaging studies in staging and therapy of head and neck neo-plasms. Semin Oncol 1994;21:340–348.

28. Phelps PD. Carcinoma of the larynx—the role of imaging instaging and pre-treatment assessments. Clin Radiol 1992;46:77–83.

29. van Dijke CF, van Waes PF. Head and neck tumors, MRI versusCT: a technology assessment pilot study. Eur J Radiol 1992;14:235–239.

30. Som PM. Detection of metastasis in cervical lymph nodes: CT andMR criteria and differential diagnosis. AJR Am J Roentgenol 1992;158:961–969.

31. Swartz JD, Yussen PS, Popky GL. Imaging the soft tissues of theneck: non-nodal acquired disease. Crit Rev Diagn Imaging 1991;31:471–547.

32. Yousem DM, Som PM, Hackney DB, Schwaibold F, Hendrix RA.Central nodal necrosis and extracapsular neoplastic spread incervical lymph nodes: MR imaging versus CT. Radiology 1992;182:753–759.

33. Hoover LA, Wortham DG, Lufkin RB, Hanafee WN. Magnetic res-onance imaging of the larynx and tongue base: clinical applica-tions. Otolaryngol Head Neck Surg 1987;97:245–256.

34. Sakai F, Gamsu G, Dillon WP, Lynch DA, Gilbert TJ. MR imag-ing of the larynx at 1.5 T. J Comput Assist Tomogr 1990;14:60–71.

35. Harris KG, Smith TP, Cragg AH, Lemke JH. Nephrotoxicity fromcontrast material in renal insufficiency: ionic versus nonionicagents. Radiology 1991;179:849–852.

36. Haustein J, Niendorf HP, Krestin G, et al. Renal tolerance ofgadolinium-DTPA/dimeglumine in patients with chronic renalfailure. Invest Radiol 1992;27:153–156.

37. Wippold FJ. Diagnostic imaging of the larynx. In: Cummings CW,Flint PW, Haughey BH, et al., editors. Otolaryngology—head andneck surgery. 4th ed. ed. St. Louis: C.V. Mosby; 2005. p 2026–2053.

38. Wippold FJ. Postoperative pharynx. In: Gore RM, Levine MS, ed-itors. Textbook of gastrointestinal radiology. 2nd ed. Philadelphia:W.B. Saunders; 2000. p. 257–270.

39. Kalender WA, Vock P, Polacin A, Soucek M. [Spiral-CT: a newtechnique for volumetric scans. I. Basic principles and methodol-ogy]. Rontgenpraxis 1990;43:323–330.

40. Pavlicek W, Geisinger M, Castle L, et al. The effects of nuclearmagnetic resonance on patients with cardiac pacemakers. Radi-ology 1983;147:149–153.

41. Klucznik RP, Carrier DA, Pyka R, Haid RW. Placement of a ferro-magnetic intracerebral aneurysm clip in a magnetic field with afatal outcome. Radiology 1993;187:855–856.

42. Kelly WM, Paglen PG, Pearson JA, San Diego AG, Soloman MA.Ferromagnetism of intraocular foreign body causes unilateralblindness after MR study. AJNR Am J Neuroradiol 1986;7:243–245.

43. Rumboldt Z, Moses C, Wieczerzynski U, Saini R. Diffusion-weighted imaging, apparent diffusion coefficients, and fluid-atten-uated inversion recovery MR imaging in endophthalmitis. AJNRAm J Neuroradiol 2005;26:1869–1872.

44. Hickman SJ, Wheeler-Kingshott CA, Jones SJ, et al. Optic nervediffusion measurement from diffusion-weighted imaging in opticneuritis. AJNR Am J Neuroradiol 2005;26:951–956.

CT and MRI in Head and Neck Imaging 463

45. Rybicki FJ, Chung T, Reid J, Jaramillo D, Mulkern RV, Ma J. Fastthree-point dixon MR imaging using low-resolution images forphase correction: a comparison with chemical shift selective fatsuppression for pediatric musculoskeletal imaging. AJR Am JRoentgenol 2001;177:1019–1023.

46. Laine FJ, Nadel L, Braun IF. CT and MR imaging of the centralskull base. Part 1: Techniques, embryologic development, andanatomy. Radiographics 1990;10:591–602.

47. Laine FJ, Nadel L, Braun IF. CT and MR imaging of the centralskull base. Part 2. Pathologic spectrum. Radiographics 1990;10:797–821.

48. Yagi A, Sato N, Taketomi A, et al. Normal cranial nerves in thecavernous sinuses: contrast-enhanced three-dimensional con-structive interference in the steady state MR imaging. AJNR Am JNeuroradiol 2005;26:946–950.

49. Naganawa S, Koshikawa T, Fukatsu H, Ishigaki T, Aoki I, Ni-nomiya A. Fast recovery 3D fast spin-echo MR imaging of the innerear at 3 T. AJNR Am J Neuroradiol 2002;23:299–302.

50. Lane JI, Ward H, Witte RJ, Bernstein MA, Driscoll CLW. 3-Timaging of the cochlear nerve and labyrinth in cochlear-implantcandidates: 3D fast recovery fast spin-echo versus 3D construc-tive interference in the steady state techniques. AJNR Am J Neu-roradiol 2004;25:618–622.

51. Maheshwari S, Mukherji SK. Diffusion-weighted imaging fordifferentiating recurrent cholesteatoma from granulation tissueafter mastoidectomy: case report. Am J Neuroradiol 2002;23:847–849.

52. Laine FJ, Braun IF, Jensen ME, Nadel L, Som PM. Perineuraltumor extension through the foramen ovale: evaluation with MRimaging. Radiology 1990;174:65–71.

53. Kaylie DM, Wax MK, Weissman JL. Preoperative facial muscleimaging predicts facial function after facial nerve grafting. AJNRAm J Neuroradiol 2003;24:326–330.

54. Schmalfuss IM, Tart RP, Mukherji SK, Mancuso AA. Perineuraltumor spread along the auriculotemporal nerve. AJNR Am J Neu-roradiol 2002;23:303–311.

55. Chang PC, Fischbein NJ, McCalmont TH, et al. Perineural spreadof malignant melanoma of the head and neck: clinical and imagingfeatures. AJNR Am J Neuroradiol 2004;25:5–11.

56. Babbel RW, Harnsberger HR. A contemporary look at the imagingissues of sinusitis: sinonasal anatomy, physiology, and computedtomography techniques. Semin Ultrasound CT MR 1991;12:526–540.

57. Weissman JL, Tabor EK, Curtin HD. Magnetic resonance imag-ing of the paranasal sinuses. Top Magn Reson Imaging 1990;2:27–38.

58. Som PM, Dillon WP, Fullerton GD, Zimmerman RA, Rajago-palan B, Marom Z. Chronically obstructed sinonasal secre-tions: observations on T1 and T2 shortening. Radiology 1989;172:515–520.

59. Williams 3rd DW. An imager’s guide to normal neck anatomy.Semin Ultrasound CT MR 1997;18:157–181.

60. Sigal R. Oral cavity, oropharynx, and salivary glands. Neuroimag-ing Clin N Am 1996;6:379–400.

61. Kurabayashi T, Ida M, Yasumoto M, et al. MRI of ranulas. Neuro-radiology 2000;42:917–922.

62. Kahn JL, Wolfram-Gabel R, Bourjat P. Anatomy and imaging ofthe deep fat of the face. Clin Anat 2000;13:373–382.

63. Braun IF, Hoffman Jr JC. Computed tomography of the bucco-masseteric region: 1. Anatomy. AJNR Am J Neuroradiol 1984;5:605–610.

64. Braun IF, Hoffman Jr JC, Reede D, Grist W. Computed tomogra-phy of the buccomasseteric region: 2. Pathology. AJNR Am JNeuroradiol 1984;5:611–616.

65. Bielamowicz SA, Storper IS, Jabour BA, Lufkin RB, Hanafee WN.Spaces and triangles of the head and neck. Head Neck 1994;16:383–388.

66. Ikeda M, Motoori K, Hanazawa T, et al. Warthin tumor of thepatorid gland: diagnostic value of MR imaging with histopatho-logic correlation. AJNR Am J Neuroradiol 2004;25:1256–1262.

67. Motoori K, Iida Y, Nagai Y, et al. MR imaging of salivary ductcarcinoma. AJNR Am J Neuroradiol 2005;26:1201–1206.

68. Takagi Y, Sumi M, Sumi T, Ichikawa Y, Nakamura T. MR micros-copy of the parotid glands in patients with Sjogren’s syndrome:quantitative MR diagnostic criteria. AJNR Am J Neuroradiol 2005;26:1207–1214.

69. Patel RR, Carlos RC, Midia M, Mukherji SK. Apparent diffusioncoefficient mapping of the normal parotid gland and parotid in-volvement in patients with systemic connective tissue disorders.AJNR Am J Neuroradiol 2004;25:16–20.

70. Kalinowski M, Heverhagen JT, Rehberg E, Klose KJ, WagnerH-J. Comparative study of MR sialography and digital subtractionsialography for benign salivary gland disorders. AJNR Am J Neu-roradiol 2002;23:1485–1492.

71. Curtin HD. Separation of the masticator space from the parapha-ryngeal space. Radiology 1987;163:195–204.

72. Fruin ME, Smoker WR, Harnsberger HR. The carotid space inthe suprahyoid neck. Semin Ultrasound CT MR 1990;11:504–519.

73. van den Berg R, Verbist BM, Mertens BJA, van der Mey AGL, vanBuchem MA. Head and neck paragangliomas: improved tumordetection using contrast-enhanced 3D time-of-flight MR angiog-raphy as compared with fat-suppressed MR imaging techniques.AJNR Am J Neuroradiol 2004;25:863–870.

74. Tryhus MR, Smoker WR, Harnsberger HR. The normal and dis-eased masticator space. Semin Ultrasound CT MR 1990;11:476–485.

75. Hardin CW, Harnsberger HR, Osborn AG, Doxey GP, Davis RK,Nyberg DA. Infection and tumor of the masticator space: CT eval-uation. Radiology 1985;157:413–417.

76. Rossiter JL, Hendrix RA, Tom LW, Potsic WP. Intramuscular hem-angioma of the head and neck. Otolaryngol Head Neck Surg 1993;108:18–26.

77. Parker GD, Harnsberger HR, Jacobs JM. The pharyngeal mucosalspace. Semin Ultrasound CT MR 1990;11:460–475.

78. Lanzieri CF, Bangert B. Magnetic resonance imaging of the naso-pharynx. Top Magn Reson Imaging 1990;2:39–47.

79. Bolzoni A, Cappiello J, Piazza C, et al. Diagnostic accuracy ofmagnetic resonance imaging in the assessment of mandibularinvolvement in oral-oropharyngeal squamous cell carcinoma: aprospective study. Arch Otolaryngol Head Neck Surg 2004;130:837–843.

80. Imaizumi A, Yoshino N, Yamada I, et al. A potential pitfall of MRimaging for assessing mandibular invasion of squamous cell car-cinoma in the oral cavity. AJNR Am J Neuroradiol 2006;27:114–122.

81. Gordon AR, Loevner LA, Shukla-Dave A, et al. Intraobserver vari-ability in the MR determination of tumor volume in squamous cellcarcinoma of the pharynx. AJNR Am J Neuroradiol 2004;25:1092–1098.

82. Davis WL, Harnsberger HR, Smoker WR, Watanabe AS. Retropha-ryngeal space: evaluation of normal anatomy and diseases withCT and MR imaging. Radiology 1990;174:59–64.

83. Davis WL, Smoker WR, Harnsberger HR. The normal and diseasedretropharyngeal and prevertebral spaces. Semin Ultrasound CTMR 1990;11:520–533.

84. Hasegawa Y, Matsuura H. Retropharyngeal node dissection incancer of the oropharynx and hypopharynx. Head Neck 1994;16:173–180.

85. Smoker WR, Harnsberger HR. Differential diagnosis of headand neck lesions based on their space of origin. 2. The infrahy-oid portion of the neck. AJR Am J Roentgenol 1991;157:155–159.

86. Casselman JW, Biebau G. Imaging of laryngeal cancer. Acta Oto-rhinolaryngol Belg 1992;46:161–174.

87. Vokes EE, Weichselbaum RR, Lippman SM, Hong WK. Head andneck cancer. N Engl J Med 1993;328:184–194.

88. Giron J, Joffre P, Serres-Cousine O, Bonafe A, Senac JP. Pre-therapeutic evaluation of laryngeal carcinomas using computedtomography and magnetic resonance imaging. Isr J Med Sci 1992;28:225–232.

89. Sakai F, Sone S, Kiyono K, et al. MR evaluation of laryngohypo-pharyngeal cancer: value of gadopentetate dimeglumine enhance-ment. AJNR Am J Neuroradiol 1993;14:1059–1069.

90. Castelijns JA, Gerritsen GJ, Kaiser MC, et al. MRI of normal orcancerous laryngeal cartilages: histopathologic correlation. La-ryngoscope 1987;97:1085–1093.

91. Rouvier H. Anatomy of the human lymphatic system. Ann Arbor,MI: Edwards Brothers; 1938. p 1–82.

92. Kaji AV, Mohuchy T, Swartz JD. Imaging of cervical lymphadenop-athy. Semin Ultrasound CT MR 1997;18:220–249.

93. Som PM. Lymph nodes of the neck. Radiology 1987;165:593–600.

464 Wippold

94. Dillon WP, Harnsberger HR. The impact of radiologic imaging onstaging of cancer of the head and neck. Semin Oncol 1991;18:64–79.

95. Maeda M, Kato H, Sakuma H, Maier SE, Takeda K. Usefulness ofthe apparent diffusion coefficient in line scan diffusion-weightedimaging for distinguishing between squamous cell carcinomasand malignant lymphomas of the head and neck. AJNR Am JNeuroradiol 2005;26:1186–1192.

96. Fischbein NJ, Noworolski SM, Henry RG, Kaplan MJ, Dillon WP,Nelson SJ. Assessment of metastatic cervical adenopathy usingdynamic contrast-enhanced MR imaging. AJNR Am J Neuroradiol2003;24:301–311.

97. Sumi M, Sakihama N, Sumi T, et al. Discrimination of metastaticcervical lymph nodes with diffusion-weighted MR imaging in pa-

tients with head and neck cancer. AJNR Am J Neuroradiol 2003;24:1627–1634.

98. Takashima S, Noguchi Y, Takeuchi N, et al. Head and neck carci-noma: detection of extraorgan spread with MR imaging and CT.Eur J Radiol 1992;14:228–234.

99. Anzai Y, Blackwell KE, Hirschowitz SL, et al. Initial clinical expe-rience with dextran-coated superparamagnetic iron oxide for de-tection of lymph node metastases in patients with head and neckcancer. Radiology 1994;192:709–715.

100. Anzai Y, McLachlan S, Morris M, Saxton R, Lufkin RB. Dextran-coated superparamagnetic iron oxide, an MR contrast agent forassessing lymph nodes in the head and neck. AJNR Am J Neuro-radiol 1994;15:87–94.

CT and MRI in Head and Neck Imaging 465