Extended quantitative dynamic contrast‐enhanced cardiac perfusion imaging in mice using accelerated data acquisition and spatially distributed, two‐compartment exchange modeling

Abstract

The objective of the present work was to improve data acquisition and quantification of dynamic contrast‐enhanced perfusion imaging in the in vivo murine heart. Four‐fold undersampled data were acquired in 14 mice and reconstructed using k‐t SPARSE. A two‐compartment exchange model was employed to provide additional characterization of myocardial tissue based on compartment volumes and the permeability surface area product. The feasibility of the proposed method was tested using compartment‐based analysis of contrast‐enhanced perfusion data acquired with intravascular and extracellular contrast agents. A significantly different permeability surface area product was measured for the intravascular versus extracellular contrast agent (0.13–0.15 ml/g/min vs 0.86–0.88 ml/g/min). The reduced extravasation also resulted in significantly smaller interstitial volumes of the intravascular versus extracellular agent (9.8–11% vs 45–47%). No difference was found for myocardial blood flow (6.5–7.2 ml/g/min vs 6.0–7.0 ml/g/min). The results presented here show that two‐compartment exchange modeling in the in vivo murine heart is feasible and gives access to tissue parameters beyond myocardial blood flow.

Quantitative myocardial first‐pass perfusion imaging of CO2‐induced vasodilation in rats

“…Previous reports of first pass perfusion (FPP) utilized motion compensation either directly, in the reconstruction step, 37 or after reconstruction with image registration. 40 However, in this work no benefits of motion compensation with image registration were found.…”

“…Other reports that examined first‐pass perfusion in mice with k‐t accelerated data acquisition used reconstruction with k‐t BLOSM 37 (R = 6 for AIF and R = 4 for myocardial uptake) or k‐t SPARSE 40 (R = 4). Previous reports of first pass perfusion (FPP) utilized motion compensation either directly, in the reconstruction step, 37 or after reconstruction with image registration 40 . However, in this work no benefits of motion compensation with image registration were found.…”

“…The data were reconstructed with k‐t PCA, which was shown to perform well for larger undersampling factors 48 and was previously used to reconstruct first‐pass perfusion data in mice with an acceleration factor of R = 10 45,46 . Other reports that examined first‐pass perfusion in mice with k‐t accelerated data acquisition used reconstruction with k‐t BLOSM 37 (R = 6 for AIF and R = 4 for myocardial uptake) or k‐t SPARSE 40 (R = 4). Previous reports of first pass perfusion (FPP) utilized motion compensation either directly, in the reconstruction step, 37 or after reconstruction with image registration 40 .…”

“…Such an approach allows for unbiased estimation of the AIF and myocardial uptake curves. A similar approach was used to record perfusion in mice, [37][38][39][40] while other studies in rats using contrast-enhanced perfusion relied on a semiquantitative approach, 41,42 with only a single slice recorded for both AIF and myocardial uptake estimation. To facilitate imaging of a rapid passage of contrast bolus, the acquisition was undersampled in the k y -t domain by a net factor R = 5.3.…”

“…The acceleration of data acquisition was necessary to obtain a sufficient temporal resolution as fast heart rates in rodents preclude a full sampling of k-space during a single heartbeat. Previous reports employed either sensitivity-encoding 29,43,44 or k-t undersampling 37,40,[45][46][47] to accelerate data acquisition with an acceleration factor varying from R = 2 to R = 10. The data were reconstructed with k-t PCA, which was shown to perform well for larger undersampling factors 48 and was previously used to reconstruct first-pass perfusion data in mice with an acceleration factor of R = 10.…”