PURPOSE: To evaluate the enhancement features of liver parenchyma and tumors using intravenous contrast enhanced imaging with multidetector CT (MDCT).
METHOD AND MATERIALS: 25 patients with hepatic tumors (16 metastases, 6 HCC, 1 each of cholangiocarcinoma, FNH and hemangioma), and 3 patients with suspected metastases but no detectable neoplasm were scanned using multiphasic CT technique. All studies were performed with a MDCT (Lightspeed, GE) with 150cc of IV contrast injected at 4cc/sec. Scans were performed as unenhanced, early arterial dominant [A](20 sec), late arterial [LA](40 sec) as well as a portal venous phase [PV](60 sec) using 2.5 & 5 mm collimation, table speed 15mm/sec. ROI's of the liver in all phases in regions without tumor involvement, as well as tumors and the portal vein were obtained. Images were also evaluated as to which phase was optimal for lesion detection and for peritumoral features such as rim enhancement.
RESULTS: Maximum enhancement of the liver parenchyma (130 HU)and the portal vein (200 HU) was achieved in the PV phase. 64% (16/25) of patients had maximal tumor to parenchymal difference in the PV phase (range 10-148 HU). In the remaining 9, tumor to parenchymal difference was highest in the late arterial (6) and arterial (3) phase of enhancement. Eight of these 9 latter patients had hypervascular tumors (2 HCC, 4 neuroendocrine, 1 each of FNH and metastatic leiomyosarcoma). Characterization features such as peritumoral enhancement were superior in the LA phase in 14/25 (56%) patients. In 4 additional patients (3 with neuroendocrine tumors and 1 HCC) more lesions were seen in the LA phase. In remaining 7 patients, tumor definition was superior in the arterial phase in 2, PV phase in 3 and equal in 2.
CONCLUSIONS: Multiphasic imaging with a MDCT found maximal liver parenchymal, and tumor to parenchymal enhancement difference in the PV phase. However, the late arterial phase was useful for defining peritumoral enhancement and detection of additional lesions in patients with hypervascular tumors especially neuroendocrine neoplasms. (IRF received research support from BErlex and Coulter Pharmaceuticals. JFP received research support from Berlex, GE Medical Systems.)
