Evaluation of iron deposition in diabetic kidney disease using the kidney-to-muscle signal intensity ratio on routine MRI T2WI sequences.

Abstract

Objective: The T2* technique in Blood Oxygen Level Dependent Magnetic Resonance Imaging (BOLD-MRI) has been established as a non-invasive standard for quantifying tissue iron levels. This study aims to assess the feasibility of obtaining quantitative iron-sensitive information from conventional MRI T2-weighted imaging (T2WI) sequences, typically used for anatomical rather than quantitative assessments, and to explore its potential as a routine monitoring tool for renal iron levels in diabetic kidney disease (DKD).

Methods: A total of 142 patient imaging data from renal MRI scans were retrospectively analyzed. We measured the kidney and psoas major muscle signal intensity on T2WI sequences and calculated the kidney-to-muscle signal intensity ratio (K/M-SIR) to determine differences across patient groups. Relevant laboratory indices were collected to analyze the correlation between K/M-SIR and laboratory markers.

Results: We included 42 clinically confirmed DKD patients, 47 patients with diabetes but no DKD, and 53 healthy subjects. The K/M-SIR was 2.66 ± 0.49 in DKD patients, 2.94 ± 0.51 in diabetic patients without DKD, and 2.95 ± 0.55 in healthy subjects. There were statistically significant differences in K/M-SIR between DKD patients and healthy subjects (p = 0.008) and between DKD patients and diabetic patients without DKD (p = 0.009). K/M-SIR values were negatively correlated with laboratory indices such as glycated hemoglobin (HbA1c), microalbuminuria (MAU), albumin-to-creatinine ratio (ACR), and 24-hour urinary protein (24 h UP).

Conclusion: The kidney-to-muscle signal intensity ratio (K/M-SIR) derived from routine MRI T2WI sequences is valuable for diagnosing DKD and may serve as a reliable non-invasive marker for assessing renal iron deposition in DKD, potentially aiding in the diagnosis and monitoring of DKD severity.