Dynamic sequential MR imaging of focal liver lesions: initial experience in 22 patients at 1.5 T.

The feasibility of dynamic sequential magnetic resonance (MR) imaging of focal hepatic lesions using Gd-diethylenetriamine pentaacetic acid (DTPA) was evaluated in this study. Three patients with hepatocellular carcinoma, 12 patients with metastases, and 7 patients with hemangiomas were studied with pre- and postcontrast multislice spin echo (SE) images using a repetition time of 500 ms and an echo time of 15 ms. The dynamic distribution phase of Gd-DTPA (0.1 mmol/kg) was investigated by using a sequential, transverse partial flip imaging sequence [fast low angle shot (FLASH)] before and after intravenous administration of Gd-DTPA. The lesion-liver contrast-to-noise ratio showed a great variability in patients with metastases and was significantly improved following administration of Gd-DTPA in patients with hemangiomas, two patients with hepatocellular carcinoma, and eight patients with metastases both on FLASH and SE images. Hemangiomas appeared darker than liver parenchyma on precontrast SE and FLASH images, increasingly enhanced over 5 min postinjection (pi) on FLASH images, and were still greatly enhanced at 10 min pi on SE images. During the dynamic sequential image acquisition the contrast enhancement of hemangiomas was significantly different from the enhancement observed in malignant lesions. The results of this study indicate the clinical potential of dynamic sequential imaging for the MR assessment of focal hepatic lesions.