Quadruple-phase MDCT of the liver in patients with suspected hepatocellular carcinoma: Effect of contrast material flow rate

OBJECTIVE. The purposes of this study were to evaluate the effect of contrast material flow rate (3 mL/sec vs 5 mL/sec) on the detection and visualization of hepatocellular carcinoma (HCC) with MDCT and the safety profile of iodixanol at different injection rates. SUBJECTS AND METHODS. In a prospective, randomized multicenter trial, 97 patients (83 men and 14 women, with a mean age of 64 years) suspected of having HCC underwent quadruple-phase (double arterial, portal venous, delayed phase) 4- 16-MDCT. Patients were randomized to receive iodixanol, 320 mg I/mL (1.5 mL/kg body weight), at a flow rate of 3 mL/sec (48 patients) or 5 mL/sec (49 patients). Qualitative (lesion detection, image quality) and quantitative (liver and aortic enhancement, tumor-liver contrast) analyses and safety assessment were performed. RESULTS. Overall, 145 HCCs were detected in the 5 mL/sec group and 100 HCCs in the 3 mL/sec group (p < 0.05). More lesions equal to or less than I cm were detected at 5 mL/sec (33 vs 16 lesions). The late arterial phase showed significantly more lesions than the early, arterial phase (133 vs 100 and 96 vs 67 lesions, respectively, p < 0.0001). Hyperattenuating HCCs were better visualized in the late arterial phase at 5 mL/sec (excellent visualization: 54% vs 27%). Using a flow of 5 mL/sec did not increase the rate of patient discomfort or contrast media-related adverse events. Most discomfort in both groups was of mild intensity and there was no severe discomfort. CONCLUSION. For detection of HCC with MDCT, a higher flow rate of 5 mL/sec is recommended. Visualization of hyperattenuating HCC is improved with no greater discomfort or adverse events.