SEQUENTIAL-CHANGES OF SONOGRAPHIC AND COMPUTED-TOMOGRAPHY FINDINGS INTHE NORMAL RABBIT LIVER AFTER PERCUTANEOUS ETHANOL INJECTION - CORRELATION WITH PATHOLOGICAL FINDINGS

RATIONALE AND OBJECTIVES. The authors assessed the sequential sonograp hic and computed tomographic (CT) findings and their correlations with pathologic findings of the normal rabbit liver after percutaneous eth anol injection (PEI). METHODS. In 30 anesthetized rabbits, 1 mL of eth anol was injected percutaneously under sonographic guidance. The anima ls were divided into five groups of six rabbits each according to the times of sonography and CT examinations after PEI: day 1 (immediately after), day 3, week 1, week 2, and week 4, The radiologic findings wer e analyzed regarding echogenicity (sonography) and density patterns be fore and after contrast administration (CT), The relations between rad iologic findings and pathologic findings were examined using statistic al analysis. The lesion size was measured using sonography and CT and compared with the actual size of the pathologic specimen, RESULTS. Son ography and CT showed various radiologic findings according to the tim e elapsed after PEI, The livers were hyperechoic in 100% (6/6) of the rabbits on day 1; this changed to isoechoic (67%, 12/18) or slightly h ypoechoic (22%, 4/18) after week 1 through week 4 after PEI on sonogra phy, CT scanning showed well-defined, hypodense lesions with no contra st enhancement in 100% (6/6) of the rabbits on day 1, and the lesions were slightly hypodense and relatively poorly defined in 88% (21/24) a fter day 3, Peripheral enhancement was noted in 83% (15/18) after week 1, Histopathologic examination revealed thrombosis and atrophic hepat ic cell cords correlating well with hyperechogenicity on sonography an d very low density on CT immediately after PEI, Coagulation necrosis w as a main pathologic finding in the central portion of the lesions aft er day 3 and correlated with the CT findings of central low density wi thout contrast enhancement, After week I, peripheral granulation tissu e and fibrosis were correlated with peripheral contrast enhancement on CT. Lesion size was largest in the week 1 group, and the size differe nce was statistically significant between the week 1 group and the day 1 group. CONCLUSIONS. Sonographic and CT findings of the PEI-treated normal rabbit liver varied with time in a predictable manner and corre lated with pathologic findings. After a week, the PEI-treated normal l iver shows perilesional enhancement that is nodular and irregular (par ticularly until 2 weeks); this must be taken into account when evaluat ing the therapeutic effect after PEI using conventional CT studies. Al though longterm data are missing, control CT scans for residual tumor should not be performed before the second week after PEI because of th e difficulty discerning enhancing tumor from enhancing fibrosis.