Adrenal adenomas and nonadenomas: assessment of washout at delayed contrast-enhanced CT.
OBJECTIVE
To measure the changes in wash-in and washout of contrast material on contrast material-enhanced computed tomographic (CT) scans in patients with adrenal adenomas and nonadenomas.


METHODS
One hundred twenty-two patients with 135 adrenal masses (74 adenomas, 61 nonadenomas) underwent helical CT. Unenhanced CT was followed by enhanced CT at 30, 60, and 90 seconds and 3, 10, and 30 minutes.


RESULTS
The adenomas enhanced significantly more than the nonadenomas at 60 seconds (P < .001), but the percentage enhancement of the adenomas was significantly greater than that of the nonadenomas at 30, 60, and 90 seconds (P < .001). At 3, 10, and 30 minutes, the absolute percentage loss of enhancement and the relative percentage loss of enhancement were significantly greater for the adenomas than for the nonadenomas (P < .001). Delayed enhanced CT at 10 minutes (sensitivity, 92%; specificity, 95%) and 30 minutes (sensitivity, 97%; specificity, 100%) was more accurate for differentiation of adenomas and nonadenomas than unenhanced CT (sensitivity, 82%; specificity, 95%).


CONCLUSIONS
Adrenal adenomas exhibit greater washout of contrast material than do adrenal nonadenomas. The percentage change in washout of contrast material is a useful adjunct to absolute CT attenuation values in differentiation of adrenal adenomas and nonadenomas.
Szolar
D H
DH
Department of Radiology, Karl-Franzens Medical School and University Hospital, Graz, Austria.
Kammerhuber
F H
FH
D000236:Adenoma / Q000000981:diagnostic imaging* / Q000473:pathology; D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000556:secondary; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001706:Biopsy; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000473:pathology; D002648:Child; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods
D003287:Contrast Media; D007472:Iohexol; C038192:iopromide