Measurement of Renal Perfusion Using ASL-MRI and Renal Oxygenation Using BOLD-MRI in Dogs

In mammals, kidney diseases are a prevalent condition. In dogs, the occurrence of chronic kidney disease is assessed to be between 0.5-7% (Lund EM. Et al). Renal fMRI is a non-invasive technique that can quantify renal function but is not routinely used in dogs. In this pilot study, we assess whether renal perfusion and oxygenation can be used in dogs. Three healthy Beagles were imaged on a Siemens PrismaFit 3T. For one Beagle the scan session was repeated one week later.
For kidney perfusion, Renal blood flow (RBF) is measured, using Arterial Spin labeling (ASL) sequence (Siemens WIP ASP 1023H).
For kidney oxygen consumption, a multi-echo GRE sequence with 12 equally spaced echo times, was used to generate Blood oxygen level-dependent (BOLD) contrast.
RBF maps were computed on the scanner. R2* maps were estimated in MATLAB-R2021b. TLCO (Twelve-Layer Concentric Objects) method (Piskunowicz M. et al) was implemented to calculate mean R2* and RBF in outer and inner layers of each kidney.
Measured RBF [ml/min/100g] in outer layers of right (R) and left (L) kidney was, R: 324.42 ± 63.83 and L: 341.02 ± 77.25 respectively. For inner layers, RBF was R: 139.76 ± 58.91 and L: 161.81 ± 59.58.
Measured BOLD [s-1] in outer layers of the kidney was R: 30.70 ± 7.19 and L: 23.97 ± 3.02. For inner layers, BOLD was R: 18.69 ± 4.64 and L: 19.00 ± 5.01.
These pilot scans confirm the viability of ASL-BOLD-MRI for canine renal assessment. The RBF values obtained in the cortex are similar to the ones obtained in previous ASL studies. The BOLD-MRI measurements in dogs tend to diverge and this sequence requires more refinement. This pilot study allows to compare RBF and BOLD among several subjects. These results are complementary upcoming study, with double sessions for 10 dogs.