Non-invasive quantification of hepatic fat fraction by fast 1.0, 1.5 and 3.0 T MR imaging.

INTRODUCTION: Even mild hepatic steatosis in a split liver donor may cause general liver failure and death in the donor. So far, CT density measurements or percutaneous biopsy is used to determine the presence of hepatic steatosis. Magnetic resonance imaging (MRI) may be an elegant method of non-invasive and non-radiation quantification of hepatic fat content. METHODS: Fast gradient echo (GRE) technique was used to discriminate between fat and water spins. Echo time (TE) was adjusted for field strength dependent in-phase and out-of-phase states at 1.0, 1.5 and 3.0 T. Continuous MR signal transition from 100% water to 100% fat was investigated using a wedge water-oil phantom, which was positioned in such a way, that no spatial resolution occurred, thereby combining water and fat in one slice. RESULTS: Using the phantom, a significant difference for a 5% difference in fat content was demonstrated in the range from 20 to 80% fat content (p<0.05) for all tested field strengths. In 25 patients MRI data were correlated with the percentage of fat determined by histologic evaluation of a CT-guided liver biopsy. Using the linear correlation calculated from the MRI phantom data at 1.0 T, we determined the liver fat from each patient's MRI measurements. Comparison of these data with the histologic quantified fat fraction of liver tissue showed a strong correlation (r(2)=0.93 for TE 6 ms and r(2)=0.91 for TE 10 ms). CONCLUSION: The described method can be used to determine the presence of hepatic steatosis of >10% with p<0.05.

Preoperative application of selective angiographic embolization in the treatment of focal nodular hyperplasia.

A focal nodular hyperplasia (FNH) rarely requires surgical intervention unless complications or clinical symptoms come into play. In 2 female patients, ages 35 and 44, with symptomatic tumors of that entity (10 and 14 cm, respectively, in size) we performed a laparoscopic liver resection. Directly before undergoing this operation they underwent a selective angiographic embolization of the arterial inflow for control of hemorrhage by application of polyvinyl alcohol particles to the afferent arteries. This procedure led to a complete interruption in arterial inflow and the subsequent laparoscopic resection itself could be carried out as planned with minimal blood loss as well an uncomplicated postoperative course. The patients demonstrated a high degree of subjective satisfaction with the procedure. A reduction in arterial inflow through selective embolization is a useful tool in the preparation for laparoscopic resection of large, well-vascularized liver tumors.