Comparison of dynamic CT and dynamic MR imaging for detection of hepatocellular carcinoma

Dynamic study using contrast agents have been used to detection of the hepatocellular carcinoma (HCC). Some reports indicated that the detectability of small nodules in liver with MRI-dynamic study is significantly superior to that with CT-dynamic study. However, these reasons are unknown. Therefore, the contrast, temporal and spatial resolutions were compared for dynamic studies of MRI and CT. Two contrast phantoms were made for MRI and CT. Both phantoms were constructed using same dilute rates of contrast material: Gd-DTPA and Iodine. The signal intensity of some different dilute rate's contrast media was measured for comparison of signal to noise ratio (SNR), contrast to noise ratio (CNR) and contrast. Time-intensity curves simulated with pharmacokinetic compartment model were evaluated for temporal resolution. In addition, the spatial resolution of CT and MR images were compared using the modulation transfer function (MTF). In the results, contrasts of phantoms with MRI and CT-dynamic study were almost same. However, MRI-dynamic study were superior to CT-dynamic study for SNR and contrast. For the distributed rates of contrast media at aortic phase, MRI-dynamic study was higher than helical CT-dynamic study but same as Multi detector-row CT (MDCT). For spatial resolution, CT images were superior to MR images. Therefore, it was recommended that MRI-dynamic study should be examined for fatty patients and MDCT-dynamic study should be examined for thin patients. (author)