BASIC CONCEPTS IN DIAGNOSTIC IMAGING J.J. Jimenez, M.D. A. Tamrazi PhD Carle Clinic Association...
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Transcript of BASIC CONCEPTS IN DIAGNOSTIC IMAGING J.J. Jimenez, M.D. A. Tamrazi PhD Carle Clinic Association...
BASIC CONCEPTS IN DIAGNOSTIC IMAGING
J.J. Jimenez, M.D.
A. Tamrazi PhD
Carle Clinic Association
University of Illinois College of Medicine
Outline
• Introduction• X-Rays• Fluoroscopy
– GI
– GU
• CT• MR• Innovative Modalities
Modalities Available in Radiology
• Plain Film / X-Ray/Mammography
• Fluoroscopy
• Ultrasound
• CT
• MRI
• Nuclear Medicine/Molecular Imaging
• Angiography/Interventional
Relative Cost of Imaging Studies
Relative Availability of Diagnostic Imaging
Teaching
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Suburban
Commun-ity Hosp
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Rural
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Plain Film
Fluoro U/S CT NM MRI Angio-interven-tional
X-Rays
• Discovered in 1895 and still used today
• Most widely performed imaging exam
• X Rays are emitted and detected in cassette
• Cassette can generate either a film or a digital image
• Films are kept ‘on file’ or in a digital archive
Most Useful Applications for Plain X-Rays
• Chest
• Musculoskeletal
• Abdomen: limited usefulness
Plain X-RaysPros Cons
• Widely available• Inexpensive• Doesn’t require
advanced technologist knowledge
• Can be performed quickly
• Portable
• Ionizing Radiation• Relatively insensitive• Requires patient
cooperation
Fluoroscopy
• Utilizes X-Rays
• Real-time imaging
• Utilizes image intensifier
• Involves use of contrast agents
Main Uses of Fluoroscopy
• Gastrointestinal Imaging
• Genitourinary Imaging
• Angiography
• Other– Intraoperative– Foreign body removal– Musculoskeletal
FluoroscopyPros Cons
• Widely Available• Inexpensive• Functional and
Anatomic• No sedation required
• Requires ingestion/injection of contrast
• Patient cooperation• Time consuming
Gastrointestional Fluoroscopy
• Esophogram/Barium Swallow
• Modified Barium Swallow/Dysphgiagram
• Upper GI
• Small Bowel Series
• Enteroclysis
• Contrast Enema
• Defecography
Single Contrast vs Double Contrast
• Single Contrast– Generally uses just thin Barium– Distends lumen with high density material– Easier for patient/less mucosal detail
• Double Contrast/Air Contrast– Thick barium coats lumen– Effervescent tablets ingested to distend lumen with air– Produces ‘see-through’ images with greater mucosal
detail – Greater sensitivity for small lesions, polyps, ulcers
Single ContrastBarium Enema
Double ContrastBarium Enema
Single Contrast vs Double Contrast
Contrast Materials for GI Exams
• Barium Sulfate– Thick: used in double contrast studies– Thin: used in single and double contrast exams– Paste: mod Ba swallow and defogography
• Gastrograffin– Full stregnth: rarely used– Dilute
Gastrograffin Swallow StudyBarrium Swallow Study
Barium vs Gastrograffin
Barium Sulfate
• Most widely used
• Better images than gastrograffin
• ‘Chalky taste’
• Peritonitis may develop if perforation
• If delayed transit, may form concretions in colon
Gastrograffin
• Water soluble• Foul Taste• Poor mucosal coating
– Basically used for R/O obstruction
• Won’t cause peritonitis if perforation• May cause severe chemical pneumonitis if aspirated• Osmotic pressure draws fluid into bowel lumen
– Progressive distention in small bowel obstruction– ‘Therapeutic’ enema in constipation
Patient Factors in GI Fluoroscopy
• Ability to ingest contrast– In order to get high quality images, a relatively large
volume of contrast needs to be ingested fairly quickly
• Mobility– Multiple positions required for GI exams, particularly
double contrast exams.– Limited mobility = less diagnostic images
• Weight– Tables have weight limits– Requires maximal radiographic technique and exposure is
often suboptimal
Esophogram or Barium Swallow
• Evaluates pharynx and esophagus
• Limited evaluation of stomach
• Double or Single Contrast
• Mucosal contour and Motility
Modified Barium Swallow
• AKA Dysphagiagram and at Carle “cookie swallow”
• Performed with Speech Pathologist• Barium administered in various bolus
consistencies ranging from liquid to solid• Evaluates swallowing mechanism• Evaluates for aspiration• Performed on videotape
Modified Barium Swallow
Upper GI Exam
• Evaluates esophagus, stomach and duodenum
• Double or Single Contrast
• Can be combined with small bowel series
• Largely replaced by endoscopy and cross-sectional imaging
• Fairly insensitive
Small Bowel Series
• Patient drinks 2 cups of thin Ba
• Overhead films obtained at routine intervals
• The Ba column is followed through until it reaches the colon
• Transit time, mucosal contour, bowel loop distribution are evaluated.
• Insensitive for small masses
Small Bowel Series
Small Bowel Enteroclysis
• “Double Contrast Small Bowel Series• NGT placed at duodenal-jejunal junction• Ba injected followed by methylcellulose• See-through appearance to small bowel• Greater sensitivity for small masses and
mucosal lesions• Patient discomfort related to NGT and
diarrhea
Contrast Enemas
• Barium or Gastrograffin
• Double contrast or single contrast
• Generally less sensitive than endoscopy
• Requires bowel prep to assess for mucosal lesions
• Requires some element of patient cooperation
Single ContrastBarium Enema
Double ContrastBarium Enema
Contrast Enemas
Defecogram
• Barium paste is inserted into rectum
• Patient is asked to defecate under fluoroscopy
• Ano-rectal and pelvic floor dynamics can be assessed
• Rectocele, intussusception, pelvic floor relaxation, stress incontinence
Genitourinary Fluoroscopy
• Cystogram
• Voiding cystourethrogram
• Retrograde urethrogram
• Hysterosalpingogram
Cystogram
• Usually in adult patients
• Looking for tear or intraluminal mass
• Catheter placed and bladder filled with contrast to capacity: usually 300-500 ml.
• Spot films obtained when full
• Post void film: usually overhead
Cystogram with Intraperitoneal Rupture
Cystogram
Voiding CystourethrogramVCUG
• Usually in children with history of UTI
• Searching for vesicoureteral reflux
• In males, evaluate for urethral abnormalities: posterior urethral valves
• Same as cystogram except when full patient voids under fluoro with spot films
Retrograde UrethrogramRUG
• Male patients
• Pelvic Trauma
• Post-infectious: STD- looking for stricture
• Different techniques
• Meatus occluded and contrast injected into urethra under fluoro
Retrograde UrethrogramRUG
Hysterosalpingogram
• Used to evaluate endometrial canal and fallopian tubes
• Infertility and uterine anomalies
• Dye injected into cervical os under fluoro
• Injection continued with goal to opacify the fallopian tubes and spill contrast into peritoneum
Musculoskeletal Fluoroscopy
• Fracture/Dislocation reduction
• Hardware placement in the OR
• Flexion/Extension views of c-spine
• Arthrography– May be performed in conjunction with MRI or
CT
Techniques Relevant to MSK Radiology
• Radiography (routine and specialized views)
• CT
• MRI
• US
• Densitometry
• Interventional procedures (arthrography, percutaneous biopsy/vertebroplasty)
MRI—Sagittal Knee T1 Weighted
MSK Radiology
Vertebroplasty
Computed Tomography (CT)• Cross Sectional imaging modality
• Mobile X-ray tube that rotates around a pt
• Slices of X-ray transmission data reconstructed to generate image
• Data displayed in multiple window settings (lungs parenchyma, bone, etc.)
• Density measurements/Hounsfield Units analyze chemical component of tissue
• HU: -150-0 = fat, 0 = water, 0-20 = serous fluid, 45-75 = blood,
100-1000 = bone/calcium
CT Contrast Agents• Intravenous contrast---iodinated
Differentiate blood vessels vs. vascular internal organs
• Enteric contrast---barium
Differentiate bowel vs. intra-abdominal fluid/masses
• Rectal contrast
• Retrograde urinary bladder contrast
CT Applications• Neuro-imaging
-Acute head trauma, acute intracranial hemorrhage
-Low sensitivity for early ischemic stroke, intracranial metastatic disease, white matter degenerative disease
• Head and Neck imaging-Soft tissue of neck, paranasal sinuses, temporal
bone imaging, orbital wall imaging
CT Applications• Body Imaging
-Chest, Abdomen, Pelvis (with enteric and IV contrast)
• Pulmonary nodules, Renal Calculi (without contrast)
• Acute appendicitis (with enteric and IV contrast)
• Specialized protocols:
-Liver masses, pancreatic tissue, renal masses, adrenal masses
CT Applications• Acute Abdomen
-decrease rate of false laparotomy procedures
• Trauma Spine Imaging (cervical, thoracic, lumbar)
• Other osseous structures (pelvis, extremities)
• Vascular Imaging
-CT angiography--- i.e. coronary arteries
CTAxial, with oral contrast in stomach
CT PET PET/CT
CTA(CT Angiography)
CT Cardiac Imaging
The Power of CT
Magnetic Resonance Imaging (MRI)
• Multi-planar scanning
• Without ionizing radiation
• Images generated using powerful magnets and pulsed radio waves passing through the body
• Data from Pt’s body used to generate image
• Field strength of magnets 0.3-3.0 Tesla
MR Contrast Agents• Intravenous contrast---Gadolinium chelate-
based contrast agents
• Gadolinium is a paramagnetic lanthanide that is toxic as a free metal
• Contrast to evaluate BBB, intracranial edema and hemorrhage
• Novel agents being developed as tagged Monoclonal antibodies for Molecular Imaging
MR Applications• Neuro-imaging
-Excellent tool due to high soft tissue contrast resolution
-Abundant water content of CNS allows for imaging soft intracranial tissue
• Head and Neck imaging-Multi-planar capability allows for monitoring
extent of disease
-Differentiating subtle soft tissue boundaries of head and neck
MRIAxial, T2-Weighted
MR Applications
• Body Imaging
-Thorax: mediastinal, hilar, chest wall abnormalities
• Limited lung imaging due to artifacts
• New advances in breast imaging
• Potentials for cardiac MRI with coronary MR angiography
MRIBreast Imaging
MR Applications
• MSK Imaging
- High sensitivity for neoplastic, inflammatory, and traumatic conditions of bone and soft tissue
- T1-weighted---fluid collections and abnormalities in fatty marrow
- T2-weighted---lesions in both marrow and soft tissue
MRISagittal, T1-Weighted
Innovative Modalities• Constantly evolving face of radiology
• New contrast agents for CT and MR
• Molecular Imaging
- Imaging molecular events---enzymatic activity, receptor binding, cellular events
• Interventional Radiology and Interventional Neuroradiology