MR IMAGING OF SMALL HEPATOCELLULAR-CARCINOMA - EFFECT OF INTRATUMORAL COPPER CONTENT ON SIGNAL INTENSITY

Small (< 5 cm) hepatocellular carcinomas (HCCs) in 45 of 112 patients (40.2%) had a high-signal-intensity pattern (relative to that of liver) on T1-weighted magnetic resonance (MR) images. To identify the cause of this pattern, specimens of histologically defined HCC with high- (n = 21), iso- (n = 6), and low- (n = 22) intensity patterns were histologically evaluated for paramagnetic ionic forms of metals. The incidence of steatosis, clear cell formation, and copper accumulation was statistically (P < .01) higher in tumors with the high-intensity pattern than in those with other patterns. Of 17 HCCs that stained positive for copper, 16 (94%) had a high-intensity pattern; the pattern of one tumor (6%) was isointense. All 21 tumors with the high-intensity pattern had at least one of the findings of steatosis, clear cell formation, or copper accumulation. These features were evident in only four of 28 tumors (14%) with an isoor low-intensity pattern. Thus, copper accumulation might be a cause of the high-intensity pattern on T1-weighted images of small HCCs.