Perfusion-corrected mapping of cardiac regional blood volume in rats in vivo.

Measurement of regional blood volume (RBV) in the myocardium in vivo is important for the assessment of tissue viability and function. The method in this work is based on the acquisition of a T(1) map before and after intravascular contrast agent application. It is known that this method is influenced by perfusion that causes an overestimation of RBV values. In order to solve this problem, the new method is proposed which acquires T(1) maps with slice selective inversion pulses. Due to blood flow nonexcited spins enter the detection slice, which leads to an acceleration of the relaxation time. A model that divides tissue into two compartments is adapted to slice selective inversion in order to derive a simple expression for perfusion-corrected RBV. The aim of the study is to demonstrate the feasibility and accuracy of this technique for quantification of RBV in rat myocardium in vivo. RBV maps were obtained for five rats, and the reproducibility was determined by repeating the experiment several times. A mean RBV value of 12.8 +/- 0.7% (v/v) over all animals was obtained in the myocardium. The results were compared with RBV maps obtained with perfusion-sensitive RBV imaging in the same five rats and with first-pass RBV studies. In order to demonstrate the strength of the new method the vasodilator adenosine was administered and alterations in microcirculation were imaged. Magn Reson Med 42:500-506, 1999.