Quantitative parameters of diffusion tensor imaging in the evaluation of carpal tunnel syndrome

Nhu Quynh Vo; Ngoc Thanh Hoang; Duy Duan Nguyen; Thi Hieu Dung Nguyen; Trong Binh Le; Nghi Thanh Nhan Le; Thanh Thao Nguyen

doi:10.21037/qims-21-910

Quantitative parameters of diffusion tensor imaging in the evaluation of carpal tunnel syndrome

Quant Imaging Med Surg. 2022 Jun;12(6):3379-3390. doi: 10.21037/qims-21-910.

Authors

Nhu Quynh Vo¹, Ngoc Thanh Hoang¹, Duy Duan Nguyen², Thi Hieu Dung Nguyen³, Trong Binh Le¹, Nghi Thanh Nhan Le⁴, Thanh Thao Nguyen¹

Affiliations

¹ Department of Radiology, University of Medicine and Pharmacy, Hue University, Hue, Vietnam.
² Department of Internal Medicine, University of Medicine and Pharmacy, Hue University, Hue, Vietnam.
³ Department of Physiology, University of Medicine and Pharmacy, Hue University, Hue, Vietnam.
⁴ Department of Surgery, University of Medicine and Pharmacy, Hue University, Hue, Vietnam.

Abstract

Background: To explore the value of diffusion tensor imaging (DTI)-derived metrics in quantitative evaluation of carpal tunnel syndrome (CTS).

Methods: This prospective cross-sectional study included 39 wrists from 24 symptomatic CTS patients, who underwent clinical, electrophysiological, and magnetic resonance imaging (MRI) evaluations. In addition, 10 wrists of 6 healthy participants were included as controls. Clinical and nerve conduction study (NCS) findings were evaluated and graded according to the Boston Carpal Tunnel Questionnaire (BCTQ) and the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM), respectively. We performed MRI using a 1.5 Tesla scanner. Mean diffusivity (MD), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) of the median nerve at the distal radioulnar joint (DRUJ) (d), the inlet of the carpal tunnel (CT) at the pisiform level (i), the middle of the CT (m) and the outlet of the CT at the level of the hook of hamate (o), cross-sectional area at the inlet of the CT (iCSA), and the difference between MD and FA of the DRUJ and the outlet of CT (Delta MD and Delta FA) were measured.

Results: The CTS patients had significantly lower FA [for example, oFA: mean difference 0.09, 95% confidence interval (CI): 0.05 to 0.12] and significantly higher MD than healthy participants (for example, iMD: mean difference 0.3, 95% CI: 0.03 to 0.57). There was a negative correlation between iCSA with iFA and between mFA and oFA (-0.5<R<-0.4). There was a positive correlation between distal motor latency time and Delta MD (R=0.57) and a negative correlation between distal motor latency time and Delta FA (R=-0.51). The FA demonstrated a somewhat strong negative correlation with the Boston scores for symptom and function.

Conclusions: The DTI-derived quantitative metrics add potential value to the evaluation of CTS. Alterations in the FA of the median nerve along the CT are the most significant features of CTS and reflect the degree of median nerve compression and clinical deficit. With a cutoff value of 0.45, FA at the carpal outlet has a sensitivity and specificity of 87.5% and 85.7% in the diagnosis of CTS, respectively.

Keywords: Boston Carpal Tunnel Questionnaire; Carpal tunnel syndrome (CTS); apparent diffusion coefficient (ADC); diffusion tensor imaging (DTI); fraction anisotropy; magnetic resonance imaging (MRI); nerve conduction study (NCS).