High-resolution 8 Tesla imaging of the formalin-fixed normal human hippocampus.

The purpose of this study was to evaluate the capacity of high-resolution magnetic resonance imaging (MRI) to visualize the normal anatomic features of the human hippocampus in vitro, using high field imaging equipment, parameters, and acquisition times appropriate for imaging human subjects in vivo. This research compared high field, high-resolution MRI of formalin-fixed normal human hippocampus specimens to histologic sectioning of the same hippocampus samples. Four specimens were evaluated using an 8 Tesla (T), 80 cm bore whole-body MRI scanner equipped with a 12.7 cm single strut transverse electromagnetic resonator (TEM) coil. Hahn spin echo images were acquired with a repetition time (TR) of 800 msec, echo times (TE) of 20, 50, 90, and 134 msec, and an acquisition time (TA) of 3.25 min. The image quality was superb with demonstration of most of the features of the hippocampus. High field, high-resolution MRI can be used to depict multiple layers of the formalin-fixed human hippocampus in vitro using an 8 T whole-body scanner, a TEM coil, and short acquisition times compatible with human imaging in vivo.

Volumetric analysis of mice lungs in a clinical magnetic resonance imaging scanner.

Small animal models are widely used to study various pathologies. Magnetic resonance imaging (MRI) allows investigation of these animals in a non-invasive way. Therefore, the aim of our study was to develop and evaluate a low-cost approach to measure lung volumes in small animal MRI using a clinical scanner and a specially designed RF coil. Five mice (three of an established emphysema model and two controls) were investigated in a 1.0-T clinical scanner using a specially built small animal saddle coil and three different three-dimensional sequences; overall imaging time was approximately 16 min. Lung volumes were calculated from these images using an interactive watershed transform algorithm for semi-automatic image segmentation. The gold standard for the volume measurement was water displacement after surgical explantation. MRI measured volumes correlated significantly with ex vivo measurements on the explanted lungs (r = 0.99 to 0.89; p < 0.05). Mean lung volume in emphysema model mice was larger than in controls. High-resolution, small animal MRI using a clinical scanner is feasible for volumetric analysis and provides an alternative to a dedicated small animal scanner.