Focal Hepatic Lesions: US-guided Biopsy-Lessons from Review of Cytologic and Pathologic Examination Results

Purpose: To retrospectively assess factors affecting the success of ultrasonographically (US)-guided core liver biopsy of focal lesions on the basis of experience when both cytologic and pathologic examination results were available. Materials and Methods: This HIPAA-compliant retrospective study was granted an exemption from the institutional review board. All percutaneous US-guided biopsies of focal liver lesions performed at one institution from January 2000 through February 2006 for which both cytologic and pathologic examination results were available were included. Specimen adequacy was determined with on-site cytologic examination performed with a "touch prep" technique. Of 1910 liver biopsies, 240 (12.6%) revealed focal lesions, and cytologic and pathologic examination results were available for 208 (86.7%) of these 240 lesions. The number of biopsy passes and concordance between cytologic and pathologic findings were evaluated, and correlation between lesion size, type, and location and the number of passes was assessed. The Pearson correlation chi(2) test and the Wilcoxon test were used. Results: Biopsy specimens were diagnostic in 205 cases (98.6%) and were nondiagnostic in three cases (1.4%); 85.9% of the lesions were malignant. There was a single lesion in 89 patients (42.8%), and there were multiple lesions in 119 patients (57.2%). One biopsy pass was sufficient in 58 patients (27.9%); two passes were sufficient in 75 patients (36.1%); and three, four, five, and six passes were sufficient in 51 (24.5%), 17 (8.2%), five (2.4%), and two (1.0%) patients, respectively. There was no relationship between lesion size or location and the number of passes, according to the Pearson correlation and chi(2) test (P = .16 and P = .22, respectively). On average, 1.9 passes were required for metastatic lesions, versus 2.8 for nonmetastatic lesions (P < .001, Wilcoxon test). Cytologic and histopathologic findings were discordant in 25 cases (12.0%). Conclusion: The size and location of liver lesions sampled for biopsy do not influence the number of passes needed, while metastatic lesions require fewer passes. Without the on-site cytologic examination service, a predetermined number of three passes would be diagnostic in almost 90% of all cases. (C) RSNA, 2008