High‐resolution ¹H NMR imaging of regional ischemia in the isolated perfused rabbit heart at 4.7 T

Abstract

High-resolution 1H NMR images of the isolated perfused rabbit heart were recorded before and after the induction of regional ischemia while the heart was arrested. On T2-weighted images the ischemic region appeared darker than the surrounding tissue and a 28% reduction in T2 was measured from the images. Infusion of an NMR contrast agent demonstrated that the hypointense region on the T2-weighted image was from the ischemic region, which was further confirmed by histological analysis of the heart. It is proposed that the decreased T2 in the ischemic region may be a consequence of changes in water compartmentalization. It is possible that these changes may be used to follow the evolution of tissue injury during ischemia, and therefore provide information regarding the transition between reversible to irreversible injury in the isolated perfused heart.

Direct histological validation of diffusion tensor MRI in formaldehyde-fixed myocardium

“…Using a "linescan" technique (17), we estimated the T 2 of our fixed myocardium to be 55 msec. This is significantly shorter than the T 2 of 90 msec reported for crystalloid buffer-perfused rabbit myocardium (18). As in our perfused heart imaging study (15), we used a TE that was approximately 66% of the T 2 , specifically 34 msec.…”

On the Origins of Diffusion MRI Signal Changes in Stroke

“…How then do we explain DW image changes associated with ischemia in non-neural tissues, which do not contain glial cells? MR microscopy studies of isolated perfused hearts with MR microscopy exposed to an ischemic event show an immediate decrease in the ADC ( 39 ) and T 2 ( 40 ) after the ischemic insult. Without the osmoregulatory glial cells, the myocytes, themselves, will swell, leading to a change in the ADC and T 2 with cell swelling in a straightforward intra/extracellular tissue model of water exchange.…”