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Progress in diagnostic computed tomography (CT) and magnetic resonance (MR) imaging has been remarkable. Multidetector-row CT provides thin-slice images through the upper abdomen, multiphase abdominal imaging, and 3D images of high quality including CT angiography and multiplanar reformation. The development of MR units provides diffusion-weighted images for detecting abdominal tumors, and the steady-state coherent echo method can be used for imaging of vessels without using contrast media. The 3D images provided in CT and MR imaging facilitate anatomic understanding of tumors and vessels and are useful for preoperative navigation. However, we must be careful when using 3D images for diagnosis, because the subjectivity of the 3D image creator may affect the results. Therefore the original axial images should also be referred to.

It is important to clarify the process by which hypovascular nodules progress to hypervascular hepatocellular carcinoma (HCC). In this study, we used dynamic computed tomography(CT) to retrospectively investigate serial changes in 24 hypovascular nodules of 24 patients until they progressed to hypervascular HCC. The mean time to hypervascular transformation(THT) was 726 days, with a minimum of 208 days and maximum of 2,728 days. Mean nodular diameter at the final examination was 21.2 +/- 8.0 mm, and was significantly larger than that(11.4 +/- 4.8 mm) at the initial time. THT was the shortest(463 days) in a group that had an initial nodular diameter larger than 15 mm. In a group with the low-iso-low contrast enhancement pattern, THT was 361 days, and was shorter than that in the other groups. In a group with the low-low-low contrast enhancement pattern, nodules containing fat were frequently detected(5 patients, 75%). In patients with HCC apart from the nodules, THT for the nodules was 464 days, shorter than that(767.5 days) in other patients. The findings suggest that hypovascular nodules larger than 15 mm in diameter with the low-iso-low contrast enhancement pattern and HCC progress to hypervascular HCC at an early stage.

Diffusion-weighted imaging (DWI) has not commonly been performed for assessment of the liver because of technical and physiologic problems. The sensitivity-encoding (SENSE) technique enables the acquisition time to be shortened and reduces artifacts on DWI. We compared the DWI without SENSE, with SENSE only, and with SENSE and half-Fourier technique using a 1.5 Tesla MRI unit. In general, imaging quality was improved and fewer artifacts were observed in DWI with SENSE. DWI of liver with SENSE is expected to be a useful tool for clinical application.

Objective: We assessed the efficacy of double arterial phase CT with multidetector CT for the detection of hypervascular hepatocellular carcinoma in the cirrhotic liver., Materials and Methods: Double arterial phase images with multidetector CT were evaluated using quantitative, qualitative, and receiver operating characteristic analyses for 59 patients with 78 hepatocellular carcinomas. Early and late arterial phase (double arterial phase) CT scans were obtained at a fixed time of 25 and 40 sec, respectively, after administration of contrast material. Total dose and injection rate of contrast material were 100 mL and 3 mL/sec, respectively., Results: On the basis of the receiver operating characteristic curves, the mean area under the curve values of the late (0.98) and combined arterial phase CT scans (0.98) were equivalent, and both were significantly greater than the mean of the early arterial phase CT scans (0.842) for detecting hepatocellular carcinoma (p < 0.05). The mean relative sensitivity values obtained with the late (69/78, 88%) and combined arterial phase CT scans (70/78, 90%) were also equivalent and were significantly greater than those obtained with the early arterial phase CT scans (52/78, 67%; p < 0.001)., Conclusion: Double arterial phase CT with multidetector CT showed no significant improvement in effectiveness compared with single late arterial phase CT used alone for detecting hypervascular hepatocellular carcinoma in the cirrhotic liver.