The washout rate on the delayed CT image as a diagnostic tool for adrenal adenoma verified by pathology: a multicenter study.
OBJECTIVE
To establish the undisputed the value of washout rate for adrenal adenoma using delayed enhanced CT, we evaluated diagnostic performance of cut-off value and delayed time of washout rate by final pathologic diagnosis in a multicenter study.


METHODS
We reviewed the pathologic and clinical records of 244 patients underwent adrenalectomies at 5 university hospitals between 2005 and 2009. We calculated the mean Housfield units (HU) of adrenal lesion at non-enhancing CT, and early and delayed enhanced CT using the region of interest. We used ROC curves to determine the specificity and sensitivity of non-enhanced CT scans and the washout rate according to the various cut-off for adrenal adenomas.


RESULTS
We divided the patients into adrenal adenoma group (n = 138) and non-adrenal adenoma group (n = 106) based on final pathologic report. Using the unenhanced images with a threshold of 10 HU, the sensitivity was 45.7 %, and the specificity was 97.1 %. Using the 15-min-washout rate with a threshold of 55 %, the sensitivity was 93.9 %, and the specificity was 95.8 %.


CONCLUSIONS
Regardless of various CT machines and protocols, a washout rate of 15-min-delayed CT was most useful in the diagnosis of adrenal adenomas due to the early inflow and outflow of contrast media in the tissues of adrenal adenomas.
Department of Urology, Pusan National University Yangsan Hospital, Yangsan, Korea. psw-ooz@hanmail.net
Sung-Woo
SW
Park
Tae Nam
TN
Kim
Jang Ho
JH
Yoon
Tae Hyo
TH
Kim
Jae Min
JM
Chung
Ung Bae
UB
Jeon
Wan
W
Lee
D000236:Adenoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000556:secondary; D000315:Adrenalectomy; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D003287:Contrast Media / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010673:Pheochromocytoma / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D012372:ROC Curve; D011859:Radiography; D012189:Retrospective Studies; D013997:Time Factors; D055815:Young Adult
D003287:Contrast Media