Perfusion MR imaging with a superparamagnetic iron oxide using T2-weightedand susceptibility-sensitive echoplanar sequences: Evaluation of tumor vascularity in hepatocellular carcinoma

OBJECTIVE. The study purpose was to examine the usefulness of perfusion ech oplanar MR imaging with a superparamagnetic iron oxide (SHU-555A) for evalu ating the vascularity of hepatocellular carcinomas. SUBJECTS AND METHODS. Twenty-two patients with 32 hepatocellular carcinomas underwent perfusion imaging with bolus injection (0.7-1.1 ml) of SHU-555A. Echoplanar sequences included multishot spin-echo (17 patients) and single -shot gradient-echo (five patients) imaging. Image acquisition was repeated every 30 sec for 3 min with the multishot spin-echo sequence and every 2 s ec for 100 sec with the single-shot gradient-echo sequence. Lesion signal i ntensity versus time curves were created for quantitative analysis. RESULTS. Transient decreases in tumor signal intensity (28.8% with multisho t spin-echo and 63.3% with the single-shot gradient-echo) were seen in the perfusion phase. These decreases in signal intensity were statistically sig nificantly (p <.01) different for each histologic type of hepatocellular ca rcinoma (poorly differentiated, 43.3%; well differentiated, 18.4%; and mode rately differentiated, 24.8%). After the perfusion phase, the tumor signal intensities rapidly recovered. The multishot spin-echo sequence could detec t some signal changes even in lesions smaller than 1 cm. CONCLUSION. Hepatocellular carcinoma vascularity can be evaluated with perf usion echoplanar imaging with SHU-555A. Because of its excellent temporal r esolution, the single-shot gradient-echo echoplanar sequence detects the tr ansient signal decrease in most lesions. The high image quality of the mult ishot spin-echo echoplanar sequence allows evaluation of the vascularity of even very small lesions.