SINGLE-PASS CT OF HEPATIC-TUMORS - VALUE OF GLOBULAR ENHANCEMENT IN DISTINGUISHING HEMANGIOMAS FROM HYPERVASCULAR METASTASES

OBJECTIVE. The purpose of this study was to evaluate the sensitivity a nd specificity of globular enhancement for differentiating hepatic hem angiomas from hypervascular metastases on single-pass, contrast-enhanc ed CT scans. Globular enhancement was defined as enhancing nodules les s than 1 cm seen within a lesion. MATERIALS AND METHODS. Fifty CT exam inations were retrospectively evaluated in a blinded fashion by two in dependent reviewers. The CT studies were done with nonhelical techniqu e after the IV injection of 150 ml of contrast material. The series in cluded 25 patients with histologically proven hypervascular hepatic me tastases (carcinoid, islet cell carcinoma, and leiomyosarcoma) and 25 patients with clinically proven hepatic hemangiomas. Patients with hem angiomas were clinically stable for at least 2 years after the CT stud ies. A single lesion was isolated from the first-pass, contrast-enhanc ed portion of each examination; the remainder of the examination was e xcluded from the review to minimize reviewer bias. Each lesion was eva luated for (1) the presence or absence of globular enhancement (define d as enhancing nodules less than 1 cm seen within a lesion), (2) the d ensity of globular enhancement relative to that of the aorta, (3) the degree of border definition (well or poorly marginated), and (4) the p resence or absence of a hypodense halo. A diagnostic impression was th en recorded for each lesion. RESULTS. Globular enhancement was 88% sen sitive and 84-100% specific for differentiating hepatic hemangiomas fr om hypervascular metastases (p < .001). A mean of 62% of hemangiomas s howed globular enhancement isodense relative to that of the aorta; non e of the metastases showed globular, isodense enhancement. The majorit y of the metastases showed nonglobular enhancement (mean, 92%). The re viewers showed 84% agreement in the identification of (1) globular enh ancement in hemangiomas, (2) lack of globular enhancement in metastase s, and (3) globular enhancement in the combined set of all lesions. Ne ither the presence of a hypodense halo nor the degree of border defini tion was significant in distinguishing between the two groups of lesio ns, The reviewers showed 96% agreement in the categorization of metast ases and 76% agreement in the categorization of hemangiomas. There was 86% agreement in the categorization of all lesions. Overall, reviewer s diagnosed a mean of 89% of lesions correctly. A mean of 98% of metas tases and a mean of 80% of hemangiomas were diagnosed correctly. CONCL USION. Globular enhancement is highly sensitive (88%) and specific (84 -100%) for differentiating hepatic hemangiomas from hypervascular meta stases on single-pass, contrast-enhanced CT scans.