DISTINCTION BETWEEN CAVERNOUS HEMANGIOMAS OF THE LIVER AND HEPATIC METASTASES ON CT - VALUE OF CONTRAST ENHANCEMENT PATTERNS

OBJECTIVE. Differentiating between cavernous hemangiomas of the liver and hepatic metastases on the basis of single-pass, contrast-enhanced CT is a significant and frequently encountered diagnostic challenge. R ecognition of characteristic enhancement features of cavernous hemangi omas can aid in effectively distinguishing between these lesions. The purpose of this study was to determine sensitivity and specificity of dense, globular enhancement for differentiating cavernous hemangiomas and metastases during single-pass, contrast-enhanced CT.MATERIALS AND METHODS. CT appearance of 133 lesions in 91 patients with cavernous he mangiomas (44 patients) or metastases (47 patients) was retrospectivel y evaluated in a blinded review. CT examinations were performed with n onhelical technique following injection of 150 ml of contrast material , All patients with metastases had pathologic proof (n = 47), Patients with cavernous hemangiomas were clinically stable for at least 2 year s after CT (n = 43) or had tissue proof (n = 1). All lesions were eval uated based on the following criteria: (I) Type of enhancement: globul ar, linear, diffuse and homogeneous, or diffuse and heterogeneous. (Gl obular enhancement was considered to be present when enhancing nodules less than I cm in diameter were seen within lesions.) (2) Continuity of enhancing tissue: continuous or noncontinuous. (Uninterrupted colle ctions of contrast material within at least 50% of a lesion were consi dered continuous. Multiple, separate collections of contrast material were considered noncontinuous.) (3) Degree of enhancement: hypo-, iso- , or hyperdense relative to the aorta. (4) Distribution of enhancement : peripheral, central, or mixed. RESULTS. Seventy-six percent of caver nous hemangiomas had globular enhancement, compared to 10% of metastas es (p <.001). Seventy-two percent of cavernous hemangiomas had enhance ment isodense with the aorta, and 96% of metastases were hypodense (p <.001). Sixty-seven percent of cavernous hemangiomas had peripheral en hancement, compared to 38% of metastases (p <.001). The combined findi ng of globular, isodense enhancement was seen in 67% of cavernous hema ngiomas and none of the metastases. Only 10% of cavernous hemangiomas had nonglobular, hypodense enhancement, compared with 90% of metastase s. Combining all criteria, reviewers correctly classified 122 (92%) of the lesions. Presence of globular enhancement, isodense with the aort a, was 67% sensitive and 100% specific in differentiating cavernous he mangiomas from hepatic metastases. CONCLUSION. In most cases, differen tiation of cavernous hemangiomas from hepatic metastases can confident ly be made with single-pass, contrast-enhanced CT. Globular enhancemen t, isodense with the aorta, is 67% sensitive and 100% specific in diff erentiating cavernous hemangiomas and hepatic metastases.