Comparison of non-enhanced, bolus enhanced, and delayed scanning techniques in computed tomography of hepatic tumours

Non-enhanced, bolus contrast medium enhanced and 4 to 6 hours delayed computed tomography of the liver was performed in a prospective study of 53 patients. Forty patients had focal lesions, in 12 of these they were hypervascular. Contrast medium was administered as an initial bolus followed by a rapid injection of meglumine metrizoate (Isopaque Cerebral). The total iodine dose varied between 56 and 63 g, which gave an average increase in attenuation of 14 HU in normal parenchyma comparing delayed with non-enhanced scanning. Presence and extent of focal lesions were evaluated in a randomized and independent analysis by two radiologists. The percentage of examinations with correct tumour description was higher with bolus scanning (observer I 73%, observer II 75%) and delayed scanning (observer I 75%, observer II 78%) than with non-enhanced scanning (observers I and II 67%). An optimal bolus technique requires an exact timing of the contrast medium administration and scanning. Delayed scanning provides an excellent supplement when the bolus examination is suboptimal or shows equivocal findings.