Quantification of renal T2 relaxation rate by use of blood oxygen level–dependent magnetic resonance imaging before and after furosemide administration in healthy Beagles

Abstract

OBJECTIVE To assess the feasibility of blood oxygen level–dependent (BOLD) MRI for measurement of the renal T2* relaxation rate (R2*; proxy for renal oxygenation) before and after furosemide administration and to evaluate the reliability and repeatability of those measurements in healthy dogs. ANIMALS 8 healthy adult Beagles (4 males and 4 females). PROCEDURES Each dog was anesthetized and underwent BOLD MRI before (baseline) and 3 minutes after administration of furosemide (1 mg/kg, IV) twice, with a 1-week interval between scanning sessions. Mapping software was used to process MRI images and measure R2* and the difference in R2* (∆R2*) before and after furosemide administration. The intraclass correlation coefficient was calculated to assess measurement reliability, and the coefficient of variation and Bland-Altman method were used to assess measurement repeatability. RESULTS Mean ± SD baseline R2* in the renal medulla (24.5 ± 3.8 seconds−1) was significantly greater than that in the renal cortex (20.6 ± 2.7 seconds−1). Mean R2* in the renal cortex (18.6 ± 2.6 seconds−1) and medulla (17.8 ± 1.5 seconds−1) decreased significantly after furosemide administration. Mean ∆R2* in the medulla (6.7 ± 2.4 seconds−1) was significantly greater than that in the renal cortex (2.1 ± 0.7 seconds−1). All R2* and ∆R2* values had good or excellent reliability and repeatability, except the cortical ∆R2*, which had poor repeatability. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that BOLD MRI, when performed before and after furosemide administration, was noninvasive and highly reliable and repeatable for dynamic evaluation of renal oxygenation in healthy dogs.

Effects of furosemide, acetazolamide and amiloride on renal cortical and medullary tissue oxygenation in non‐anaesthetised healthy sheep

“…The caveat to this observation is that the dose of furosemide used was 10 mg/kg, approximately 20 times the dose we used in the current study and the study was conducted in anaesthetised animals. Using BOLD‐MRI, there have been consistent observations of improved medullary and/or cortical tissue oxygenation after similarly high doses of furosemide in experimental animals (Lee et al., 2021 ; Pedersen et al., 2007 ; Priatna et al., 1999 ). Interestingly, using BOLD‐MRI, improvements in renal oxygenation were also observed in healthy human volunteers given clinically relevant doses of furosemide (Epstein & Prasad, 2000 ; Haddock et al., 2019 ; Lal et al., 2022 ; Prasad et al., 1996 ).…”

“…observations of improved medullary and/or cortical tissue oxygenation after similarly high doses of furosemide in experimental animals (Lee et al, 2021;Pedersen et al, 2007;Priatna et al, 1999). Interestingly, using BOLD-MRI, improvements in renal oxygenation were also observed in healthy human volunteers given clinically relevant doses of furosemide (Epstein & Prasad, 2000;Haddock et al, 2019;Lal et al, 2022;Prasad et al, 1996).…”

Assessment of pharmacologically induced changes in canine kidney function by multiparametric magnetic resonance imaging and contrast enhanced ultrasound

“…However, some studies have produced contradictory findings, showing no distinction between healthy and diseased kidneys ( 53 , 54 ). In dogs, there has only been one prior study that used BOLD-MRI to quantify renal oxygenation to our knowledge ( 55 ). Lee et al ( 55 ) studied the feasibility and repeatability of BOLD-MRI derived T2* between two sessions in eight healthy beagles under anesthesia before and after furosemide administration.…”

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“…However, some studies have produced contradictory findings, showing no distinction between healthy and diseased kidneys (53, 54). In dogs, there has only been one prior study that used BOLD-MRI to quantify renal oxygenation to our knowledge (55). Lee et al (55) studied the feasibility and repeatability of BOLD-MRI derived T2* between two sessions in eight healthy beagles under anesthesia before and after furosemide administration.…”