Clinical Study MDCT in the Differentiation of Adrenal ...

Hindawi Publishing CorporationThe Scientific World JournalVolume 2013 Article ID 957680 7 pageshttpdxdoiorg1011552013957680

Clinical StudyMDCT in the Differentiation of Adrenal MassesComparison between Different Scan Delays for the Evaluation ofIntralesional Washout

Giuseppe Angelelli Maria Elisabetta Mancini Marco Moschetta Pasquale PedotePasquale Pignataro and Arnaldo Scardapane

DIM Interdisciplinary Department of Medicine Aldo Moro University of Bari Medical SchoolPiazza Giulio Cesare 11 70124 Bari Italy

Correspondence should be addressed to Giuseppe Angelelli gangelelliradiologiaunibait

Received 20 January 2013 Accepted 15 February 2013

Academic Editors C Corsi F Frauscher and C Kappas

Copyright copy 2013 Giuseppe Angelelli et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Purpose To evaluate the accuracy of the washout in the differential diagnosis between adenomas and nonadenomas and to comparethe obtained results in delayed CT scans at 5 10 and 15 minutes Methods Fifty patients with adrenal masses were prospectivelyevaluated CT scans were performed by using a 320-row MDCT device before and after injection of contrast material In 25 casesdelayed scans were performed at 51015840 and 101015840 (group 1) while in the remaining 25 at 51015840 and 151015840 (group 2) Absolute and relative wash-out percentage values (APW and RPW) were calculated Results Differential diagnosis between adenomas and nonadenomas wasobtained in 4850 (96) cases with sensitivity specificity and accuracy values of 96 95 and 96 respectively In group 1 APWand RPW values were respectively 698 and 672 at 51015840 and 759 and 735 at 101015840 for adenomas and 251 and 158 at 51015840 and335 and 205 at 101015840 for nonadenomas In group 2 APW and RPW values were 63 and 546 at 51015840 and 738 and 655 at 151015840for adenomas and 22 and 125 at 51015840 and 355 and 199 at 151015840 for nonadenomas Conclusions The evaluation of the wash-outvalues in CT scans performed at 51015840 101015840 and 151015840 provides comparable diagnostic results CT scans performed at 51015840 are therefore tobe preferred since they reduce the examination time and patient discomfort

1 Introduction

In recent years the detection of adrenal expansive lesionsduring CT examinations has become common even inpatients without endocrinological symptoms because of theincreasing number of investigations carried out for differentclinical problems with a prevalence varying from 035 to9 in different series [1 2]

After recognizing an expansive adrenal lesion the dif-ferentiation between adenomas and nonadenomas becomescrucial for patientrsquos prognosis and for the choice of thetherapeutic approach [3ndash6]

The role of CT for differential diagnosis has been studiedin numerous investigations and the accuracy of CT scansbefore and after injection of contrast material has beenreported even using dual energy CT scanners [7]

In case of unenhanced CT scans intralesional densityvalues of less than 10HU indicate an adenoma with highaccuracy In contrast intralesional density values greaterthan 10HU are more common in nonadenomas but theycannot exclude the possibility of adenomas with low-intra-cytoplasmic fat content [8ndash11]

CT scans after injection of contrast material mainly offerthe evaluation of the peak density and intralesional washoutfor differential diagnosis between adenomas and nonadeno-mas There is no unanimous agreement in the literature forthe optimal scan delay to evaluate this parameter accordingto some authors the optimal delay is represented by 10minutes after intravenous injection of contrast material toothers 15 minutes and according to other experiences earlierCT scans performed at 5 minutes can be used in this field[12ndash21]

2 The Scientific World Journal

The purpose of this study is to evaluate the accuracy ofthe wash-out in the differential diagnosis between adenomasand nonadenomas and to compare the results obtained in CTscans performed at 5 10 and 15 minutes after intravenousinjection of contrast material

2 Materials and Methods

Between February 2009 and December 2011 50 subjects (26males and 24 females) being diagnosed with adrenal lesionsfrom 1 to 12 cm in diameter were prospectively studied withCT All fluid cyst-like lesions or lesions with fat contentrelated to myelolipomas were excluded from our series

In 13 cases CT examination was performed for thepresence of significant endocrinological symptoms in 8cases after incidental ultrasound finding of adrenalmass andin 29 cases the diagnosis was occasional during abdominalCT examinations performed for various clinical problems

Patients were aged between 35 and 83 years (mean age59) Patients were randomly assigned to one of the followingtwo groups based on the type of late scans group 1 (scansperformed at 51015840 and 101015840) and group 2 (scans performed at 51015840and 151015840)

The lesions recognized in the first groupwere representedby 10 adenomas 4 adrenal carcinomas 1 ganglioneuroma4 pheochromocytomas and 6 metastases (4 lung carcino-mas 1 renal cell carcinoma and 1 ovarian carcinoma) inthe second group 12 adenomas 3 adrenal carcinomas 3pheochromocytomas and 7 metastases (4 lung carcinomas2 colon carcinomas and 1 melanoma)

The diagnosis was histologically confirmed in 21 cases (7adrenal carcinomas 1 ganglioneuroma 1 metastasis 7 benignpheochromocytomas and 5 adenomas) in the remainingpatients it was based on the densitometric appearance andclinical-radiological evolution of the disease as assessed byCT twice a year The mean followup was 15 years In particu-lar the absence of morphological and volumetric variationsof the lesion in the subsequent controls was consideredsignificant of adenoma while its size increase was consideredindicative of metastasis

CT examinations were performed by using a 320-rowmultidetector CT system (Aquilion One Toshiba MedicalSystems Otawara Japan) and the following acquisitionparameters were used slice thickness 05mm and increment05mm rotation time 05 s 120200 kVpmAs An automaticdose modulation system was used in all cases

In all cases images were acquired before and after intra-venous injection of contrast material (Iomeron 400 BraccoMilan Italy) injected in a quantity equal to 15mL per kg ofbody weight up to a maximum of 120mL at a flow rate of35mLper second Scanswere performed in the portal venousphase (50ndash60 seconds after the injection of contrast material)and in the late phases carried out as already reported in 25patients at 5 and 10 minutes and in 25 patients at 5 and 15minutes

The obtained data were transferred and analyzed on aworkstation (HP XW 8600) equipped with a software ded-icated to image reconstruction (Vitrea FX 21 Vital Images

Minneapolis MN USA) Axial and reconstructed imageswere analyzed by two independent blinded radiologists with30 and 6 years of experience in abdominal CT and thefollowing parameters were considered

(i) densitometry of the lesion in unenhanced scans(ii) densitometry after contrast material injection

assessed by applying a large round or oval region ofinterest (ROI) excluding any calcification areas ofnecrosis or cystic degeneration

(iii) absolute intralesional percentage wash-out (APW) inscans at 51015840 101015840 and 151015840

(iv) relative intralesional percentage wash-out (RPW) inscans at 51015840 101015840 and 151015840

In order to calculate the APW and RPW values thefollowing formulas were used respectively APW = 100 times([EAminusDA][EAminusPA]) RPW= 100times ([EAminusDA][EA]) whereEA = early-phase postcontrast attenuation DA = delayed-phase postcontrast attenuation PA = precontrast attenuationAn APW of more than 60 and an RPW of more than40were considered significant for adenoma independentlyfrom the used scan delay [12]

Analysis of our sample was performed by using descrip-tive statistics and examining precontrast and postcontrastdensity of the lesions andAPWandRPWvaluesThe sensitiv-ity specificity and diagnostic accuracy values were obtainedThe degree of concordance between the two readers wasassessed by using Cohenrsquos Kappa statistics poor concordance(119896 lt 001) low concordance (k = 001 to 020) fair agreement(k = 021 to 040) good agreement (k = 041ndash060) substantialagreement (k = 061ndash080) and almost perfect agreement (k= 081ndash100)

3 Results

Mean densitometric values for each type of lesion arereported in Tables 1 and 2 The densitometric values of theadenomas in unenhanced scans ranged between minus6 and194HU (mean 46HU standard deviation 09) In particulardensity values of less than 10HU were found in 16 out of 22(727) cases values of more than 10HUwere found in 6 outof 22 (273) cases

Nonadenomas presented an unenhanced density frombetween 14 and 439HU (mean 295 HU standard deviation92)

After intravenous injection of contrast material in theportal venous phase adenomas showed amean enhancementof 775HU (range 382 to 1324HU) while nonadenomatouslesions a mean value of 754HU (range 382ndash1881 HU)

Among the group of patients studied at 5 and 10 minutesin the scans at 51015840 the mean values of APW for adenomasranged between 61 and 792 (mean 698) and in thescans at 101015840 between 727 and 807 (mean 759) Non-adenomas ranged between 07 and 603 (mean 251)at 51015840 and between 105 and 705 (mean 335) at 101015840(Figure 1) The values of RPW for adenomas ranged between579 and 788 (mean 672) at 51015840 and between 629 and

The Scientific World Journal 3

Table 1 Mean densitometric values obtained in group 1

Group 1Adenomas Nonadenomas

Mean density in unenhanced phase(HU) 3 314

Mean density in portal phase (HU) 768 859Mean density in 51015840 delayed phase(HU) 248 661

Mean density in 101015840 delayed phase(HU) 21 613

51015840 mean APW 6980 251051015840 mean RPW 6720 1580101015840 mean APW 7590 3350101015840 mean RPW 7351 2050




Mean density in portal phase (HU) 802 613Mean density in 51015840 delayed phase (HU) 3258 5366Mean density in 101015840 delayed phase(HU) 2435 4911


821 (mean 735) at 101015840 For nonadenomas RPW rangedbetween 04 and 525 (mean 158) at 51015840 and between 53and 614 (mean 205) at 101015840

Among the group of patients studied at 5 and 15 minutesin the scans at 51015840 values between 356 and 824 (mean63) and 313 and 806 (mean 546) emerged for APWand RPW respectively in case of adenomas In 151015840 scansAPW values ranged between 442 and 914 (mean 738)and RPW values between 394 and 833 (mean 655)(Figure 2) For nonadenomas APW and RPW values at 51015840varied respectively between 119 and 33 (mean 22) andbetween 5 and 209 (mean 125) At 151015840 values rangedbetween 229 and 422 (mean 355) and between 127and 318 (mean 199)The degree of concordance betweenthe two readers was almost perfect(119896 = 082)

Basing on the wash-out of the examined lesions a differ-ential diagnosis between adenomas and nonadenomas wasobtained in 4850 (96) cases with sensitivity specificityand diagnostic accuracy values of 96 95 and 96 respec-tively In particular APW and RPW provided comparableresults and densitometric values obtained by using differentscan delays did not cause significant diagnostic changes

Among the two cases of incorrect diagnosis one wasthe case of an adrenal metastasis from renal cell carcinomain which the obtained wash-out values were significant for

adenoma In particular APW values of 603 at 51015840 and 705at 101015840 were obtained in this patient and 525 at 51015840 and 614at 101015840 were found for RPW The second case was representedby a lipid-poor adenoma in which the obtained wash-outvalues were significant for nonadenoma In particular APWwas 356 at 51015840 and 442 at 151015840 while the RPWwas 313 at51015840 and 394 at 151015840

4 Discussion

The detection of adrenal expansive lesions during CT exami-nation is frequent with a prevalence varying between 035and 9 in different series [1 2] In 50ndash80 of cases theyare represented by adenomas whereas nonadenomas aremost often represented by metastases adrenal carcinomas(lt5) pheochromocytomas (5) myelolipomas (5ndash10)and cysts (1ndash5) [22ndash24] The metastases originate moreoften from carcinomas of the lung breast kidney thyroidcolon and melanoma and represent 20ndash50 of adrenalmasses diagnosed in patients with known neoplastic disease[3 22 25] The differential diagnosis between adenomasand nonadenomas with imaging techniques is of particularimportance for an adequate prognostic and therapeuticapproach being able to avoid the use of invasive proceduressuch as biopsy or unnecessary prolonged followup

In the differentiation between adenomas and nonadeno-mas morphological histological and physiological criteriaare usually used

The morphological criteria considering the size and thehomogeneous or inhomogeneous appearance of the lesionprovide useful elements for differential diagnosis betweenadenomas and nonadenomas but need to be always combinedwith other parameters In particular adenomas are mostoften lesions with regular margins small in size with amean value of less than 3 cm and have a homogeneousdensity In autopsy series only 2 of adrenal adenomas had adiameter greater than 4 cm and 003 over 6 cm Metastasescarcinomas and pheochromocytomas on the contrary havemore frequently a diameter larger than 4 cm irregular con-tours and an inhomogeneous appearance for the presenceof areas of necrosis hemorrhage and intralesional cysticdegeneration [3 5 6 23 24 26]

The histological criteria are based on the evaluation ofintracellular lipids within the adrenal lesion About 70 ofadrenal adenomas in fact are made up of cells containingintracytoplasmic lipid deposits which represent the precur-sors of their secreted hormone and confer a low densityto the mass in the unenhanced CT scans In particular asreported in the literature an intralesional density value ofless than 0UH in unenhanced scans allows the diagnosis ofadenoma with a sensitivity of 47 and a specificity of 100[8] A sensitivity of 71ndash79 and specificity of 96ndash98are instead reported with a threshold value of 10UH usuallyconsidered in clinical practice [10 17 22 27] As reported byStadler et al slice thickness of le3mm and low Kv values areindicated for evaluating the densitometric values of adrenallesions in order to optimize the obtained results [28]


(a) (b)

(c) (d)

Figure 1 Pheochromocytoma (a) Unenhanced attenuation values 439 plusmn 41HU (b) Portal-phase attenuation values 766 plusmn 35HU (c) 51015840attenuation values 736 plusmn 319HU (d) 101015840 attenuation values 725 plusmn 327 HU Absolute percentage wash-out at 51015840 9 Relative percentagewash-out at 51015840 39 Absolute percentage wash-out at 101015840 125 Relative percentage wash-out at 101015840 53

In our experience the unenhanced scans were significantfor the differential diagnosis between adenomas and non-adenomas in 75 of cases and these data are substantiallysimilar to those reported in the literature In no case ofnonadenomas a basal density value of less than 10HU wasfound

The morphological criteria represent therefore animportant parameter of evaluation but have some limitations

(i) They do not allow a diagnostic orientation in case oflipid-poor adenomas (approximately 30 of cases)which have a density greater than 10HU

(ii) Unenhanced CT scans are often not used in thefollowup of cancer and therefore the histologicalcriteria cannot be evaluated

(iii) The possibility exists that an adrenal carcinoma con-tains foci of intracytoplasmic lipids [25] as well asexceptionally metastatic from clear cell renal carci-noma and hepatocellular carcinoma [3]

The physiological criteria are represented by the vascularenhancement and the washout of the lesion

According to some authors in the post-contrast scansperformed in the portal venous phase nonadenomas have anaverage lower density than in adenomas [14] For others how-ever these scans do not provide any element of differentialdiagnosis because both adenomas and nonadenomas show asignificant enhancement in the early phase with substantiallyoverlapped density values [12 15 16 23] These data alsoemerged in our experience in which an average density of

775HUwas found in adenomas and amean value of 754HUin case of nonadenomas

Regarding the intralesional wash-out in 1989 Krestin etal evaluated 38 adrenal masses by usingMRI with Gd-DTPAand firstly emphasized that adenomas and nonadenomascould be differentiated on this basis highlighting a morerapid wash-out of contrastmaterial in case of adenomas com-pared with pheochromocytomasand malignancies whichtend to retain the contrast material for a longer period [26]Numerous studies have subsequently emphasized the role ofthe analysis of intralesional washout in late CT scans afterintravenous injection of contrast material although there isno agreement yet on the timing of image acquisition andthe values of wash-out to be considered significant for thedifferential diagnosis

Some authors have evaluated the contribution of the latescans performed at 151015840 after the injection of contrast materialreporting a sensitivity and specificity of 79ndash89 and 92ndash96 for APW values of more than 60 and a sensitivity anda specificity of 82ndash83 and 92ndash93 for RPW values ofmore than 40 [14ndash17] Other researchers experienced theuse of scans at 10 and 5minutes in order to obtain a simplifica-tion and a reduction of execution times for CT examinationsBlake et al evaluated 122 adrenal masses by using a protocolthat included CT scans in 101015840 with a threshold value of 52for theAPWand 375 for theRPW and reported a sensitivityand specificity of 100 and 98 respectively [18] In a seriesof 323 adrenal lesions Sangwaiya et al always using a delayof 101015840 and considering different threshold values for APWand RPW obtained different results and reported sensitivity


(a) (b)

(c) (d)

Figure 2 Lipid-poor adenoma (a) Unenhanced attenuation values 194 plusmn 248HU (b) Portal-phase attenuation values 1324 plusmn 399HU (c)5 minutes attenuation values 585 plusmn 253 HU (d) 15 minutes attenuation values 391 plusmn 206HU Absolute percentage wash-out at 51015840 653Relative percentage wash-out at 51015840 558 Absolute percentage wash-out at 151015840 825 Relative percentage wash-out at 151015840 704

specificity and accuracy values respectively of 521ndash71380ndash933 and 64ndash717 for APW and of 557ndash814937ndash100 and 579ndash82 for RPW According to theseauthors anticipating the acquisition of delayed scans wouldnot provide sufficient time for the wash-out of the adenomasto be completed so the scans at 10 minutes would not beeffective in clinical practice [20] Even regarding thewash-outestimated at 51015840 there are conflicting opinions in the literatureKamiyama et al and Foti et al reported accuracy valuesgreater than 90 [19 21] while Taffel et al in a recent reviewsuggested that the further reduction of the acquisition timeof late scans at 5 minutes would decrease significantly thesensitivity of the test limiting the clinical value [3]

To our knowledge in a single paper already reported inthe literature washout curves evaluated by late scans acquiredat intervals of 51015840 101015840 151015840 301015840 and 451015840 were compared andthe authors concluded that a significantly more rapid wash-out for adenomas compared to nonadenomas was alreadyevident at 51015840 but the authors suggested the use of scans at151015840 being associated with higher sensitivity and specificityvalues for differential diagnosis (88ndash96 for a 60 APWand 96ndash100 for a 40 RPW) although no hypothesis insupport of the proposedmethodwas reported in this research[12]

Our results confirm the importance of wash-out in thedifferentiation between adenomas and nonadenomas withsensitivity specificity and diagnostic accuracy values of 9695 and 96 respectively As proposed by Korobkin et alour results have been obtained by considering APW of more

than 60 and RPW of more than 40 as significant foradenomas [12]

In this field other authors described the possibility ofmodifyingAPWandRPWthreshold values based on the scandelay after intravenous injection of contrast material In factin a recent series Park et al proposed APW values of 35 at51015840 45 at 101015840 and 55ndash60 at 151015840 for differential diagnosisThese authors reported higher sensitivity and specificityvalues at 151015840 with an APW threshold value of 55 [29]Thesedata seem different from those obtained in our experiencetherefore this issue cannot be considered as resolved andfurther studies are needed in this field

The comparison of the wash-out calculated in CT scans at51015840 and 101015840 (group 1) and at 51015840 and 151015840 (group 2) showed smallvariations of the obtained values and not significant changesfor diagnostic accuracy with high correlation between theAPW and RPW

In particular in the first group of patients themean valueof APW for adenomas was equal to 698 at 51015840 and 759 at101015840 For nonadenomas it was 251 at 51015840 and 335 at 101015840Themean value of RPW for adenomas was 672 at 51015840 and 735at 101015840 while for nonadenomas it was 158 at 51015840 and 205 at101015840

In the second group of patients by considering scansperformed at 51015840 and 151015840 mean values of APW of 63 at 51015840and 738 at 151015840 and mean values of RPW of 546 at 51015840 and655 at 151015840 emerged for adenomas In case of nonadenomasmean values of APW and RPW were respectively equal to22 and 125 at 51015840 and to 355 and 199 at 151015840


In our experience the densitometric changes useful fordifferential diagnosis therefore were already evident at 51015840and did not significantly change at 101015840 and 151015840 Even in the caseof adrenal metastasis misdiagnosed as adenoma values ofabsolute and relative wash-out significant for adenoma wereobserved both in the scans at 51015840 and 101015840 as also in the caseof the unrecognized adenoma in which densitometric valuessignificant for nonadenoma were detected both in the scansperformed at 51015840 and 151015840 It should be emphasized that in thesetwo patients neither unenhanced CT scans were significantfor a correct diagnosis The possibility that nonadenomatouslesions can mimic contrastographic features of adenomas isdescribed in the literature especially in case of pheochromo-cytomas which in the series reported by Park et al showedan APW of more than 60 in delayed scans in 16 of cases[30]

Our research has important limitations essentially rep-resented by the small number of considered patients andanyway it does not contribute to the knowledge regardingthe pathophysiology of the more rapid wash-out for ade-nomas than for nonadenomas Our results however seemto confirm the hypothesis that such behavior is determinedby an alteration of capillary permeability in case of nonade-nomas responsible for a prolonged intralesional persistenceof contrast material [13] In case of adenomas capillarypermeability is instead not changed and the washout is rapidand therefore already evident at 51015840 and does not progresssignificantly in later CT scans

5 Conclusions

Multidetector computed tomography represents anextremely sensitive imaging tool for recognizing adrenalexpansive lesions being able to detect lesions of a fewmillimeters in diameter

The intralesional washout is a very accurate parameter fordifferential diagnosis between adenomas and nonadenomasand is essential in the characterization of adenomas withoutintracytoplasmic lipids

The evaluation of the wash-out obtained in CT scansperformed at 51015840 101015840 and 151015840 after the intravenous injectionof contrast material provides diagnostic comparable resultsCT scans performed at 51015840 are therefore to be preferred sincethey reduce the examination time and patient discomfort

References

[1] M Korobkin I R Francis R T Kloos andN R Dunnick ldquoTheincidental adrenal massrdquo Radiologic Clinics of North Americavol 34 no 5 pp 1037ndash1054 1996

[2] J H Song F S Chaudhry and W W Mayo-Smith ldquoTheincidental adrenal mass on CT prevalence of adrenal diseasein 1049 consecutive adrenal masses in patients with no knownmalignancyrdquo The American Journal of Roentgenology vol 190no 5 pp 1163ndash1168 2008

[3] M Taffel S Haji-Momenian P Nikolaidis and F H MillerldquoAdrenal imaging a comprehensive reviewrdquo Radiologic Clinicsof North America vol 50 no 2 pp 219ndash243 2012

[4] J H Song and W W Mayo-Smith ldquoIncidentally discoveredadrenal massrdquo Radiologic Clinics of North America vol 49 no2 pp 361ndash368 2011

[5] GW L Boland ldquoAdrenal imaging fromaddison to algorithmsrdquoRadiologic Clinics of North America vol 49 no 3 pp 511ndash5282011

[6] G W Boland ldquoAdrenal imagingrdquo Abdominal Imaging vol 36no 4 pp 472ndash482 2011

[7] Y K Kim B K Park C K Kim and S Y Park ldquoAdenoma char-acterization adrenal protocol with dual-energy CTrdquo Radiology2013

[8] M J Lee P F Hahn N Papanicolaou et al ldquoBenign andmalignant adrenal masses CT distinction with attenuationcoefficients size and observer analysisrdquo Radiology vol 179 no2 pp 415ndash418 1991

[9] M Korobkin F J Brodeur G G Yutzy et al ldquoDifferentiationof adrenal adenomas from nonadenomas using CT attenuationvaluesrdquo The American Journal of Roentgenology vol 166 no 3pp 531ndash536 1996

[10] G W L Boland M J Lee G S Gazelle E F Halpern M MJ McNicholas and P R Mueller ldquoCharacterization of adrenalmasses using unenhanced CT an analysis of the CT literaturerdquoThe American Journal of Roentgenology vol 171 no 1 pp 201ndash204 1998

[11] P L Choyke ldquoACR appropriateness criteria on incidentallydiscovered adrenal massrdquo Journal of the American College ofRadiology vol 3 no 7 pp 498ndash504 2006

[12] M Korobkin F J Brodeur I R Francis L E Quint N RDunnick and F Londy ldquoCT time-attenuation washout curvesof adrenal adenomas and nonadenomasrdquoTheAmerican Journalof Roentgenology vol 170 no 3 pp 747ndash752 1998

[13] D H Szolar and F H Kammerhuber ldquoAdrenal adenomasand nonadenomas assessment of washout at delayed contrast-enhanced CTrdquo Radiology vol 207 no 2 pp 369ndash375 1998

[14] E M Caoili M Korobkin I R Francis R H Cohan andN R Dunnick ldquoDelayed enhanced CT of lipid-poor adrenaladenomasrdquoTheAmerican Journal of Roentgenology vol 175 no5 pp 1411ndash1415 2000

[15] M Korobkin ldquoCT characterization of adrenal masses the timehas comerdquo Radiology vol 217 no 3 pp 629ndash632 2000

[16] C S Pena G W L Boland P F Hahn M J Lee and PR Mueller ldquoCharacterization of indeterminate (lipid-poor)adrenal masses use of washout characteristics at contrast-enhanced CTrdquo Radiology vol 217 no 3 pp 798ndash802 2000

[17] E M Caoili M Korobkin I R Francis et al ldquoAdrenal massescharacterization with combined unenhanced delayed enhancedCTrdquo Radiology vol 222 no 3 pp 629ndash633 2002

[18] M A Blake M K Kalra A T Sweeney et al ldquoDistinguishingbenign from malignant adrenal masses multi-detector row CTprotocol with 10-minute delayrdquo Radiology vol 238 no 2 pp578ndash585 2006

[19] T Kamiyama Y Fukukura T Yoneyama K Takumi and MNakajo ldquoCombined use of diagnostic parameters of unen-hanced and short 5-minute dynamic enhanced CT protocolrdquoRadiology vol 250 no 2 pp 474ndash481 2009

[20] M J Sangwaiya GW L Boland CG CroninMA Blake E FHalpern and P FHahn ldquoIncidental adrenal lesions accuracy ofcharacterization with contrast-enhanced washout multidetec-tor CTmdash10-minute delayed imaging protocol revisited in a largepatient cohortrdquo Radiology vol 256 no 2 pp 504ndash510 2010


[21] G Foti N Faccioli W Mantovani G Malleo R Manfrediand R P Mucelli ldquoIncidental adrenal lesions accuracy ofquadriphasic contrast enhanced computed tomography in dis-tinguishing adenomas from nonadenomasrdquo European Journalof Radiology vol 81 no 8 pp 1742ndash1750 2012

[22] P T Johnson K M Horton and E K Fishman ldquoAdrenal massimaging with multidetector Ct pathologic conditions pearlsand pitfallrdquo Radiographics vol 29 no 5 pp 1333ndash1351 2009

[23] W F Young ldquoThe incidentally discovered adrenal massrdquo TheNew England Journal of Medicine vol 356 no 6 pp 601ndash6102007

[24] N C Dalrymple J R Leyerdecker and M Oliphant ProblemSolving in Abdominal Imaging Elsevier Health Sciences Divi-sion 2009

[25] B Mackay A El-Naggar and N G Ordonez ldquoUltrastructure ofadrenal cortical carcinomardquo Ultrastructural Pathology vol 18no 1-2 pp 181ndash190 1994

[26] G P Krestin W Steinbrich and G Friedmann ldquoAdrenalmasses evaluation with fast gradient-echo MR imaging andGd-DTPA-enhanced dynamic studiesrdquo Radiology vol 171 no3 pp 675ndash680 1989

[27] W W Mayo-Smith G W Boland R B Noto and M J LeeldquoFrom the RSNA refresher courses state-of-the-art adrenalimagingrdquo Radiographics vol 21 no 4 pp 995ndash1012 2001

[28] A Stadler W Schima G Prager et al ldquoCT density mea-surements for characterization of adrenal tumors ex vivovariability among three CT scannersrdquo The American Journal ofRoentgenology vol 182 no 3 pp 671ndash675 2004

[29] S W Park T N Kim J H Yoon et al ldquoThe washout rate on thedelayed CT image as a diagnostic tool for adrenal adenoma ver-ified by pathology a multicenter studyrdquo International Urologyand Nephrology vol 44 no 5 pp 1397ndash1402 2012

[30] B K Park B Kim K Ko S Y Jeong and G Y Kwon ldquoAdrenalmasses falsely diagnosed as adenomas on unenhanced anddelayed contrast-enhanced computed tomography pathologi-cal correlationrdquo European Radiology vol 16 no 3 pp 642ndash6472006

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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

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Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


The purpose of this study is to evaluate the accuracy ofthe wash-out in the differential diagnosis between adenomasand nonadenomas and to compare the results obtained in CTscans performed at 5 10 and 15 minutes after intravenousinjection of contrast material

2 Materials and Methods

Between February 2009 and December 2011 50 subjects (26males and 24 females) being diagnosed with adrenal lesionsfrom 1 to 12 cm in diameter were prospectively studied withCT All fluid cyst-like lesions or lesions with fat contentrelated to myelolipomas were excluded from our series

In 13 cases CT examination was performed for thepresence of significant endocrinological symptoms in 8cases after incidental ultrasound finding of adrenalmass andin 29 cases the diagnosis was occasional during abdominalCT examinations performed for various clinical problems

Patients were aged between 35 and 83 years (mean age59) Patients were randomly assigned to one of the followingtwo groups based on the type of late scans group 1 (scansperformed at 51015840 and 101015840) and group 2 (scans performed at 51015840and 151015840)

The lesions recognized in the first groupwere representedby 10 adenomas 4 adrenal carcinomas 1 ganglioneuroma4 pheochromocytomas and 6 metastases (4 lung carcino-mas 1 renal cell carcinoma and 1 ovarian carcinoma) inthe second group 12 adenomas 3 adrenal carcinomas 3pheochromocytomas and 7 metastases (4 lung carcinomas2 colon carcinomas and 1 melanoma)

The diagnosis was histologically confirmed in 21 cases (7adrenal carcinomas 1 ganglioneuroma 1 metastasis 7 benignpheochromocytomas and 5 adenomas) in the remainingpatients it was based on the densitometric appearance andclinical-radiological evolution of the disease as assessed byCT twice a year The mean followup was 15 years In particu-lar the absence of morphological and volumetric variationsof the lesion in the subsequent controls was consideredsignificant of adenoma while its size increase was consideredindicative of metastasis

CT examinations were performed by using a 320-rowmultidetector CT system (Aquilion One Toshiba MedicalSystems Otawara Japan) and the following acquisitionparameters were used slice thickness 05mm and increment05mm rotation time 05 s 120200 kVpmAs An automaticdose modulation system was used in all cases

In all cases images were acquired before and after intra-venous injection of contrast material (Iomeron 400 BraccoMilan Italy) injected in a quantity equal to 15mL per kg ofbody weight up to a maximum of 120mL at a flow rate of35mLper second Scanswere performed in the portal venousphase (50ndash60 seconds after the injection of contrast material)and in the late phases carried out as already reported in 25patients at 5 and 10 minutes and in 25 patients at 5 and 15minutes

The obtained data were transferred and analyzed on aworkstation (HP XW 8600) equipped with a software ded-icated to image reconstruction (Vitrea FX 21 Vital Images

Minneapolis MN USA) Axial and reconstructed imageswere analyzed by two independent blinded radiologists with30 and 6 years of experience in abdominal CT and thefollowing parameters were considered

(i) densitometry of the lesion in unenhanced scans(ii) densitometry after contrast material injection

assessed by applying a large round or oval region ofinterest (ROI) excluding any calcification areas ofnecrosis or cystic degeneration

(iii) absolute intralesional percentage wash-out (APW) inscans at 51015840 101015840 and 151015840

(iv) relative intralesional percentage wash-out (RPW) inscans at 51015840 101015840 and 151015840

In order to calculate the APW and RPW values thefollowing formulas were used respectively APW = 100 times([EAminusDA][EAminusPA]) RPW= 100times ([EAminusDA][EA]) whereEA = early-phase postcontrast attenuation DA = delayed-phase postcontrast attenuation PA = precontrast attenuationAn APW of more than 60 and an RPW of more than40were considered significant for adenoma independentlyfrom the used scan delay [12]

Analysis of our sample was performed by using descrip-tive statistics and examining precontrast and postcontrastdensity of the lesions andAPWandRPWvaluesThe sensitiv-ity specificity and diagnostic accuracy values were obtainedThe degree of concordance between the two readers wasassessed by using Cohenrsquos Kappa statistics poor concordance(119896 lt 001) low concordance (k = 001 to 020) fair agreement(k = 021 to 040) good agreement (k = 041ndash060) substantialagreement (k = 061ndash080) and almost perfect agreement (k= 081ndash100)

3 Results

Mean densitometric values for each type of lesion arereported in Tables 1 and 2 The densitometric values of theadenomas in unenhanced scans ranged between minus6 and194HU (mean 46HU standard deviation 09) In particulardensity values of less than 10HU were found in 16 out of 22(727) cases values of more than 10HUwere found in 6 outof 22 (273) cases

Nonadenomas presented an unenhanced density frombetween 14 and 439HU (mean 295 HU standard deviation92)

After intravenous injection of contrast material in theportal venous phase adenomas showed amean enhancementof 775HU (range 382 to 1324HU) while nonadenomatouslesions a mean value of 754HU (range 382ndash1881 HU)

Among the group of patients studied at 5 and 10 minutesin the scans at 51015840 the mean values of APW for adenomasranged between 61 and 792 (mean 698) and in thescans at 101015840 between 727 and 807 (mean 759) Non-adenomas ranged between 07 and 603 (mean 251)at 51015840 and between 105 and 705 (mean 335) at 101015840(Figure 1) The values of RPW for adenomas ranged between579 and 788 (mean 672) at 51015840 and between 629 and


















4 Discussion






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Clinical Study MDCT in the Differentiation of Adrenal ...

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