Initial Experience of Metabolic Imaging With Hyperpolarized [1‐13C]pyruvate MRI in Kidney Transplant Patients

Abstract

BackgroundKidney transplant is the treatment of choice for patients with end‐stage renal disease. Early detection of allograft injury is important to delay or prevent irreversible damage.PurposeTo investigate the feasibility of hyperpolarized (HP) [1‐13C]pyruvate MRI for assessing kidney allograft metabolism.Study TypeProspective.SubjectsSix participants (mean age, 45.2 ± 12.4 years, two females) scheduled for kidney allograft biopsy and five patients (mean age, 59.6 ± 10.4 years, two females) with renal cell carcinoma (RCC).Field Strength/SequenceThree Tesla, T2‐weighted fast spin echo, multi‐echo gradient echo, single shot diffusion‐weighted echo‐planar imaging, and time‐resolved HP 13C metabolite‐selective imaging.AssessmentFive of the six kidney allograft participants underwent biopsy after MRI. Estimated glomerular filtration rate (eGFR) and urine protein‐to‐creatine ratio (uPCR) were collected within 4 weeks of MRI. Kidney metabolism was quantified from HP [1‐13C]pyruvate MRI using the lactate‐to‐pyruvate ratio in allograft kidneys and non‐tumor bearing kidneys from RCC patients.Statistical TestsDescriptive statistics (mean ± SD).ResultsBiopsy was performed a mean of 9 days (range 5–19 days) after HP [1‐13C]pyruvate MRI. Three biopsies were normal, one showed low‐grade fibrosis and one showed moderate microvascular inflammation. All had stable functioning allografts with eGFR >60 mL/min/1.73 m2 and normal uPCR. One participant who did not undergo biopsy had reduced eGFR of 49 mL/min/1.73 m2 and elevated uPCR. The mean lactate‐to‐pyruvate ratio was 0.373 in participants with normal findings (N = 3) and 0.552 in participants with abnormal findings (N = 2). The lactate‐to‐pyruvate ratio was highest (0.847) in the participant with reduced eGFR and elevated uPRC. Native non‐tumor bearing kidneys had a mean lactate‐to‐pyruvate ratio of 0.309.Data ConclusionStable allografts with normal findings at biopsy showed lactate‐to‐pyruvate ratios similar to native non‐tumor bearing kidneys, whereas allografts with abnormal findings showed higher lactate‐to‐pyruvate ratios.Evidence Level2Technical EfficacyStage 2