The value of MR neurography in assessing lesions of the thoracic dorsal root ganglia in patients with zoster-associated pain.

Objectives: To evaluate the imaging characteristics of the thoracic dorsal root ganglia (DRG) in patients with zoster-associated pain (ZAP) using magnetic resonance neurography (MRN) and its correlation with disease stages and serological marker.

Methods: Twenty-six consecutive ZAP patients with different disease stages (acute herpes neuralgia, subacute herpes neuralgia, and postherpetic neuralgia) and thirteen healthy subjects were scanned on a 3-T MR scanner for thoracic DRG visualization. The T₁-T₁₂ DRG for each ZAP patient were divided into three groups (prominent affected segment, rash distribution segment, and non-rash distribution segment). The volume and T2 signal intensity (SI) of thoracic DRG were measured and compared. The visual analog scale (VAS) and serological data were also recorded.

Results: The volume ratio of prominent affected thoracic DRG in ZAP patients was larger than that in non-rash distribution segment of ZAP patients and that in the healthy group, respectively (both p < 0.05). The volume ratio of affected DRG in the acute herpes neuralgia and subacute herpes neuralgia group was both higher than that in the postherpetic neuralgia group (both p < 0.05). For T2 SI, no differences were found among three disease stages. The ESR index was the only parameter associated with volume ratio of prominent affected DRG segment (r = 0.48, p = 0.01).

Conclusion: MRN is able to visualize and identify morphological changes of thoracic DRG of ZAP patients. The imaging characteristics of affected thoracic DRG exhibit differences across different disease stages, which was associated with ESR index in ZAP patients.

Key points: Question Magnetic resonance neurography is able to detect the abnormal imaging features of dorsal root ganglia (DRG) in zoster-associated pain patients. Findings Magnetic resonance neurography (MRN) demonstrates a difference in the volume ratio of affected DRG among three disease stages in zoster-associated pain (ZAP) patients. Clinical relevance Combining serological parameter with observed thoracic DRG volume changes on MRN may serve as a viable predictor for ZAP development.