Pseudolesions around the Gallbladder Fossa: Comparison of Frequency and Radiological Characteristics in Multiphasic CT, CTAP, and CTHA

Abstract

Purpose: The purpose of this study is to compare the frequency with which pseudolesions around the gallbladder (GB) fossa are revealed by multiphasic CT, by CT during arterial portography (CTAP), and by CT during hepatic arteriography (CTHA) and to determine their radiological characteristics. Materials and Methods: Multiphasic CT, CTAP, and CTHA examinations of 81 patients without pathology of the GB and around the GB fossa were evaluated for pseudolesion around the GB fossa. The definition of pseudolesion was as follows: 1) hyperattenuation during the arterial phase and isoattenuation during the delayed phase of multipha-sic CT, or perfusion defect on CTAP and hyperattenuation on CTHA; 2) no Lipiodol tagging on Lipiodol CT; 3) all findings observed adjacent to the gallbladder fossa; and 4) no interval change on follow-up CTAP and CTHA. We compared the frequency of pseudolesions around the GB fossa, as seen on multiphasic CT, CTAP, and CTHA, and determined their size, location, and shape, as revealed by CTHA. Results:The frequency of pseudolesion was 2.5% (2/81) on multiphasic CT, while on CTAP or CTHA, the frequency was 53.1% (43/81), and 58 pseudolesions were identi-fied. Of 58 pseudolesions, 56 were revealed by CTAP and 57 by CTHA. Forty-nine of 58 pseudolesions were larger and all pseudolesions showed more contrast to parenchyma on CTHA than on CTAP. The location of pseudolesions was segment V(32 of 58), IV (25 of 58), and VI (1 of 58), and their size ranged from 5 to 30 (mean, 17.5)mm. Pseudolesions were wedge-shaped (48 of 58), oval (6 of 58), bandlike (3 of 58), or round (1 of 58). Conclusion: CTAP and CTHA frequently revealed pseudolesion around the GB fossa. The radiological characteristics of these modalities help differentiate pseudolesions from true tumoral hepatic lesions.