High‐resolution myocardial perfusion mapping in small animals in vivo by spin‐labeling gradient‐echo imaging

Abstract

An ECG and respiration-gated spin-labeling gradient-echo imaging technique is proposed for the quantitative and completely noninvasive measurement and mapping of myocardial perfusion in small animals in vivo. In contrast to snapshot FLASH imaging, the spatial resolution of the perfusion maps is not limited by the heart rate. A significant improvement in image quality is achieved by synchronizing the inversion pulse to the respiration movements of the animals, thereby allowing for spontaneous respiration. High-resolution myocardial perfusion maps (in-plane resolution ‫؍‬ 234 ؋ 468 m 2 ) demonstrating the quality of the perfusion measurement were obtained at 4.7 T in a group of seven freely breathing Wistar-Kyoto rats under isoflurane anesthesia. The mean perfusion value (group average ؎ SD) was 5.5 ؎ 0.7 ml g -1 min -1 . In four animals, myocardial perfusion was mapped and measured under cardiac dobutamine stress. Perfusion increased to 11.1 ؎ 1.9 ml g -1 min -1 . The proposed method is particularly useful for the study of small rodents at high fields.Magn Reson Med 51:62-67, 2004.

Imaging Experimental Cerebral MalariaIn Vivo: Significant Role of Ischemic Brain Edema

“…31, 388.99, 803.81, 1367.55, and 1969.27 s/mm 2 . Quantitative CBF maps were obtained with a Look-Locker arterial spin-labeling technique (Kober et al, 2004). A series of 50 gradient echoes was acquired after each inversion pulse.…”

“…CBF maps were calculated as described previously (Kober et al, 2004). The blood/tissue partition coefficient for water was assumed to be ϭ 0.9 ml/g (Sun et al, 2004), and T 1 of blood was determined as the average T 1 measured in a large brain vessel.…”

Myocardial blood flow mapping in mice using high‐resolution spin labeling magnetic resonance imaging: Influence of ketamine/xylazine and isoflurane anesthesia

“…This short-axis orientation and location was used for perfusion imaging. For the perfusion measurement, we used a double-gated spin labeling gradient-echo method already described elsewhere (21). A series of ECG-gated single phase-encoded gradient echoes was acquired following a global or slice-selective adiabatic inversion.…”

“…T 1 maps were calculated from the magnitude inversion recovery raw images (21). For the ifl measurement, images acquired during respiratory motion were visually identified on an image display containing all raw images and excluded from the fitting procedure.…”

“…The main advantages of this approach are high sensitivity at high spatial resolutions and the ability to accurately measure MBF in freely breathing animals in vivo. The method was successfully applied to rats breathing freely under isoflurane anesthesia (21). In the present work, we applied this technique to quantitative and spatially resolved measurements of MBF in freely breathing mice under different anesthesia conditions.…”