In vivo H MRS of Gallbladder Bile using an Optimized 8-Channel Phased Array at 3T: Towards Improved Diagnosis of Hepatopancreatobiliary Diseases

INTRODUCTION: Bile is a biofluid synthesized in the liver and stored in the gallbladder. It facilitates the emulsification, digestion, and absorption of lipids. Study of bile composition is valuable in the diagnosis of various hepatopancreatobiliary diseases. In vitro H MRS studies performed on bile samples collected during endoscopic retrograde cholangiopancreatography (ERCP) have shown diagnostic value in detecting hepatopancreatobiliary disorders [1, 2]. However, given the invasive nature of ERCP, there is a great interest in performing such analysis in vivo. The study performed by Prescot et al. using a 1.5T MRI scanner was the first to show the possibility of obtaining H MR spectra of human gallbladder (GB) bile in vivo. However, the published in vivo spectra were of low quality and not able to detect individual bile components except for phospholipids [3]. This could be due to the low magnetic field strength (1.5T), use of spin echoes with longer delays, lipid contamination and/or respiratory motion effects [3]. A more recent study performed by Kunnecke et al. on the bile composition in cynomolgus monkeys using a 4.7T and a home-built surface coil in transmit/receive mode has shown promising results [4]. However, a 4.7T scanner is not routine in clinical human studies. Moreover, safety issues should be considered when using transmit home-built coils in humans. Therefore, to address these issues, we present our initial efforts to obtain good quality spectra from pigs (with similar bile duct system as that of humans) using a 3T Siemens scanner and a home-built receive array coil.