A rapid T₁ mapping method for assessment of murine kidney viability using dynamic manganese-enhanced magnetic...

Dynamic manganese-enhanced MRI (MEMRI) allows assessment of tissue viability by tracing manganese uptake. We aimed to develop a rapid T₁ mapping method for dynamic MEMRI to facilitate assessments of murine kidney viability.

A multi-slice saturation recovery fast spin echo (MSRFSE) was developed, validated, and subsequently applied in dynamic MEMRI at 16.4T on ischemic mouse kidneys after 4 weeks of unilateral renal artery stenosis (RAS). Baseline T₁ values and post-contrast R₁ (1/T₁ ) changes were measured in cortex (CO), outer (OSOM), inner (ISOM) strips of outer medulla, and inner medulla (IM).

Validation studies showed strong agreement between MSRFSE and an established saturation recovery Look-Locker method. Baseline T₁ (s) increased in the stenotic kidney CO (2.10 [1.95-2.56] vs. 1.88 [1.81-2.00], P = 0.0317) and OSOM (2.17 [2.05-2.33] vs. 1.96 [1.87-2.00], P = 0.0075) but remained unchanged in ISOM and IM. This method allowed a temporal resolution of 1.43 min in dynamic MEMRI. Mn²⁺ uptake and retention decreased in stenotic kidneys, particularly in the OSOM (ΔR₁ : 0.48 [0.38-0.56] vs. 0.64 [0.61-0.69] s^-1 , P < 0.0001).

Dynamic MEMRI by MSRFSE detected decreased cellular viability and discerned the regional responses to RAS. This technique may provide a valuable tool for noninvasive evaluation of renal viability. Magn Reson Med 80:190-199, 2018. © 2017 International Society for Magnetic Resonance in Medicine.