Dual frequency coils and MRIS method for the characterization of ischemic injury in the intestinal wall

An in-vivo magnetic resonance imaging and spectroscopy method was developed to study the progression of ischemic injury in the intestinal wall in a rabbit model using a 4.7 T research magnet. This method is based on a custom transmit/receive intraluminal coil array and a combination of standard imaging and spectroscopy techniques adapted to this application. The specially designed double coil array consists of two orthogonal rectangular-shaped single loop coils in a cylindrical structure for intraluminal placement. Each element has a different resonant frequency: 200.4 MHz (IH) and 81.1 MHz (31P). The acquisition sequence has a duration of 25 minutes and includes high resolution T2-weighted RARE imaging, diffusion weighted imaging, 31P spectroscopy and water-suppressed 1H spectroscopy. The information obtained can be used to characterize structural, functional and metabolic changes in the tissue as ischemic injury progresses. In vivo experimental results were obtained from an anesthetized rabbit subjected to total occlusion of the superior mesenteric artery. Clear differences were observed in all of the measured variables before and after the onset of ischemia.