Multi-Detector-Row CT Diagnosis of Adrenal Incidentaloma in Patients with Hepatocellular Carcinoma

Abstract

We investigate the diagnostic reliability of differentiating between lipid-poor adrenal adenomas and metastatic adrenal tumors originating from hepatocellular carcinoma (HCC) using a routine dynamic CT protocol for liver imaging. Eighteen metastatic adrenal tumors originating from HCC and 13 lipid-poor adrenal adenomas were identified. Dynamic CT data were analyzed for CT attenuation of adrenal lesions before and after contrast administration. When a cutoff of 36 HU was set for adrenal lesions at pre-contrast attenuation, the sensitivity and specificity for the diagnosis of metastatic lesions were 94.4% and 92.3%, respectively. Attenuation criteria on pre-contrast CT may help optimize the differentiation between these lesions.

Relative Enhancement Ratio of Portal Venous Phase to Unenhanced CT in the Diagnosis of Lipid-poor Adrenal Adenomas

“…In our study, lipid-poor adenomas showed a lower unenhanced attenuation than nonadenomas (22 HU 6 6 vs 34 HU 6 7; P , .001), as in previous studies (5,(9)(10)(11)(12)(19)(20)(21)(22). Additionally, the absolute enhancement of adenomas was 1.5-fold higher than nonadenomas (P , .001), which is also corroborated by data from numerous studies wherein adenomas had higher (up to 2.2-fold) absolute enhancement compared with nonadenomas, mostly comprising metastases (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)14,16,22,29,30) (Table E4 [online]).…”

“…In our study, adenomas showed an approximately 20% and 100% higher mean absolute enhancement and relative enhancement ratio, respectively, compared with hypervascular nonadenomas. Several previous studies have demonstrated equivalent or higher absolute enhancement in adenomas than in hypervascular nonadenomas (15,19,20,23,25,27,28,(31)(32)(33), while opposite results have also been observed in some investigations (A, B) an 84-year-old man with adrenal metastasis from hepatocellular carcinoma and (C, D) a 68-yearold man with lipid-poor adenoma. The lesions in both A and C had equivalent low unenhanced attenuation.…”

“…The portal venous phase images were acquired 70-80 seconds after the start of the injection of the contrast medium. Axial images were reconstructed with a 5-mm section Additionally, a hypoattenuating property at unenhanced CT may still be a viable indicator of adenomas, even when they are classified as lipid-poor lesions based on 10-HU criteria (5,(9)(10)(11)(12)(19)(20)(21)(22). Hence, a simultaneous assessment of unenhanced attenuation and contrast wash-in characteristics may facilitate the differentiation of lipid-poor adenomas from nonadenomas.…”

“…A total of 29 relevant articles from the literature were reviewed (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(14)(15)(16)19,20,(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34). Sixteen studies provided data on both adenomas (n = 964) and nonadenomas mostly comprising metastases (n = 623), all of which showed higher absolute enhancement in adenomas than in nonadenomas (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)14,16,22,29,30) (Table E4 [online]).…”

“…Data in parentheses are numbers of adenomas, with 95% CIs in brackets. (15,19,20,23,25,27,28,(31)(32)(33); three studies (101 adenomas vs 43 pheochromocytomas, four cortical carcinomas, and 19 metastases from RCC or HCC) showed higher absolute enhancement in nonadenomas (24,26,34); and all 13 studies presented a higher relative enhancement ratio in adenomas than in hypervascular nonadenomas (Table E5 [online]).…”