Diffusion tensor imaging of diabetic amyotrophy

To qualitatively and quantitatively characterize the nerves of patients with diabetic amyotrophy (DA) using magnetic resonance neurography (MRN) with diffusion tensor imaging (DTI).

Forty controls and 13 DA cases were analyzed. 1.5-Tesla and 3.0-Tesla MRN with DTI was used. Qualitative data from 13 patient records were recorded. Region of interest (ROI) measurements were taken of bilateral L3 through S2 lumbosacral nerve roots, femoral nerves, and sciatic nerves. An ANOVA and multiple linear regression analysis were performed. An intraclass correlation coefficient (ICC) was calculated between two readers.

In DA cases, abnormalities of the lumbosacral nerve roots (n = 11 patients), sciatic (n = 10), femoral (n = 13), and obturator nerves (n = 4) were seen; denervation changes of the abdominopelvic muscles were also identified. Quantitatively, minimum and mean nerve signals on B600 were significantly less than controls (p < 0.001). Minimum and mean ADC values were significantly greater in cases than in controls (p < 0.001 and p = 0.002 respectively). Mean fractional anisotropy (FA) values were significantly lower in cases than in controls (p = 0.041). There were no significant differences in the minimum FA values between cases and controls. Minimum and mean ADCs correlated positively with highest recorded hemoglobin A1 (HbA1c) while controlling for sex, age, and BMI (β = 0.518, p < 0.001 and β = 0.302, p = 0.020 respectively). ICCs were 0.892 (B600), 0.717 (ADC), and 0.730 (FA).

Neuromuscular lesions secondary to DA are qualitatively and quantitatively identified on MRN with DTI, and a positive correlation of ADC levels with serum HbA1c levels exists. Thus, MRN with DTI can be employed as a non-invasive diagnostic tool, if DA is suspected.