In vivo assessment of absolute perfusion in the murine skeletal muscle with spin labeling MRI

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Abstract
Purpose To assess absolute perfusion in the skeletal muscle of mice in vivo with spin labeling magnetic resonance imaging (MRI) under normal and stress conditions. Materials and Methods Absolute perfusion in the skeletal muscle of 27 C57BL/6 mice was assessed in vivo non‐invasively by spin labeling MRI at 7.05 T. This technique was based on the acquisition of T1 maps with global and slice‐selective spin inversion in separate acquisitions. T1 mapping was performed by inversion recovery snapshot fast low angle shot imaging. To guarantee proper spin inversion within the whole mouse, a dedicated radiofrequency (RF) coil combination was constructed. A birdcage resonator was used for transmission, while detection of the MRI signal was achieved by a surface coil. Results Basal perfusion in the hindlimbs was determined to be 94 ± 10 mL (100 g · minute)–1 (mean ± standard error of the mean [SEM], N = 27). This value is in good agreement with perfusion values determined by invasive techniques such as microspheres. A subgroup of six animals received a constant dose of 4 mg (kg · minute)–1 of the vasodilator adenosine by an intraperitoneal catheter. In this case, perfusion was significantly increased to 179 ± 56 mL (100 g · minute)–1 (mean ± SEM, N = 6, P < 0.02). Mean basal perfusion in this subgroup was 96 ± 26 mL (100 g · minute)–1. Conclusion Spin labeling MRI is a well‐suited technique for the in vivo assessment of absolute perfusion in the murine skeletal muscle. J. Magn. Reson. Imaging 2003;17:147–152.