T1ρ mapping for assessment of renal allograft fibrosis

J Magn Reson Imaging. 2019 Oct;50(4):1085-1091. doi: 10.1002/jmri.26656. Epub 2019 Jan 21.

Abstract

Background: There is an unmet need for noninvasive methods to diagnose and stage renal allograft fibrosis.

Purpose: To investigate the utility of T1ρ measured with MRI for the assessment of fibrosis in renal allografts.

Study type: Institutional Review Board (IRB)-approved prospective.

Subjects: Fifteen patients with stable functional allograft (M/F 9/6, mean age 56 years) and 12 patients with allograft dysfunction and established fibrosis (M/F 6/6, mean age 51 years).

Field strength/sequence: T1ρ imaging at 1.5T using a custom-developed sequence.

Assessment: Average T1ρ in the cortex and medulla was quantified and T1ρ repeatability (expressed by the coefficient of variation [CV]) was measured in four patients.

Statistical tests: Differences in T1ρ values between the 2 groups were assessed using Mann-Whitney U-tests. Diagnostic performance of T1ρ for differentiation between functional and fibrotic allografts was evaluated using receiver operating characteristic (ROC) analysis. Spearman correlations of T1ρ with Masson's trichrome-stained fractions and serum estimated glomerular filtration rate (eGFR) were assessed.

Results: Higher T1ρ repeatability was found for cortex compared with medulla (mean CV T1ρ cortex 7.4%, medulla 13.3%). T1ρ values were significantly higher in the cortex of fibrotic vs. functional allografts (111.8 ± 17.2 msec vs. 99.0 ± 11.0 msec, P = 0.027), while there was no difference in medullary T1ρ values (122.6 ± 20.8 msec vs. 124.3 ± 20.8 msec, P = 0.789). Cortical T1ρ significantly correlated with Masson's trichrome-stained fractions (r = 0.515, P = 0.044) and eGFR (r = -0.546, P = 0.004), and demonstrated an area under the curve (AUC) of 0.77 for differentiating between functional and fibrotic allografts (sensitivity and specificity of 75.0% and 86.7%, using threshold of 106.9 msec).

Data conclusion: Our preliminary results suggest that T1ρ is a potential imaging biomarker of renal allograft fibrosis. These results should be verified in a larger study.

Level of evidence: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1085-1091.

Keywords: T1rho; fibrosis; renal allograft.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Female
  • Fibrosis
  • Humans
  • Image Interpretation, Computer-Assisted / methods*
  • Kidney / diagnostic imaging
  • Kidney / pathology
  • Kidney Diseases / diagnostic imaging*
  • Kidney Diseases / pathology*
  • Kidney Transplantation*
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged
  • Postoperative Complications / diagnostic imaging*
  • Postoperative Complications / pathology*
  • Prospective Studies
  • Reproducibility of Results
  • Sensitivity and Specificity