Measurement of murine kidney functional biomarkers using DCE-MRI: A multi-slice TRICKS technique and semi-automated image processing algorithm

Purpose: To propose a rapid multi-slice T₁ measurement method using time-resolved imaging of contrast kinetics (TRICKS) and a semi-automated image processing algorithm for comprehensive assessment murine kidney function using dynamic contrast-enhanced MRI (DCE-MRI). Methods: A multi-slice TRICKS sampling scheme was implemented in an established rapid T₁ measurement method. A semi-automated image-processing scheme employing basic image processing techniques and machine learning was developed to facilitate image analysis. Reliability of the multi-slice technique in measuring renal perfusion and glomerular filtration rate (GFR) was tested in normal mice (n = 7 for both techniques) by comparing to the validated single-slice technique. Utility of this method was demonstrated on mice after either sham surgery (n = 7) or induction of unilateral renal artery stenosis (RAS, n = 8). Renal functional parameters were extracted using a validated bi-compartment model. Results: The TRICKS sampling scheme achieved an acceleration factor of 2.7, allowing imaging of eight axial slices at 1.23 s/scan. With the aid of the semi-automated scheme, image analysis required under 15-min for both kidneys per mouse. The multi-slice technique yielded renal perfusion and GFR values comparable to the single-slice technique. Model-fitted renal parameters successfully differentiated control and stenotic mouse kidneys, including renal perfusion (706.5 ± 164.0 vs. 375.9 ± 277.9 mL/100 g/min, P = 0.002), blood flow (1.6 ± 0.4 vs. 0.7 ± 0.7 mL/min, P < 0.001), and GFR (142.9 ± 17.9 vs. 58.0 ± 42.8 μL/min, P < 0.001). Conclusion: The multi-slice TRICKS-based DCE-MRI technique, with a semi-automated image processing scheme, allows rapid and comprehensive measurement of murine kidney function.