Hypoperfusion of periaqueductal gray as an imaging biomarker in chronic migraine beyond diagnosis: A 3D pseudocontinuous arterial spin labeling MR imaging.

Background: The periaqueductal gray (PAG) is at the center of a powerful descending antinociceptive neuronal network, and is a key node in the descending pain regulatory system of pain. However, less is known about the altered perfusion of PAG in chronic migraine (CM).

Aim: To measure the perfusion of PAG matter, an important structure in pain modulation, in CM with magnetic resonance (MR) perfusion without contrast administration.

Methods: Three-dimensional pseudocontinuous arterial spin labeling (3D-PCASL) and brain structure imaging were performed in 13 patients with CM and 15 normal subjects. The inverse deformation field generated by brain structure image segmentation was applied to the midbrain PAG template to generate individualized PAG. Then the perfusion value of the PAG area of the midbrain was extracted based on the individual PAG mask.

Results: Cerebral blood flow (CBF) value of PAG in CM patients (47.98 ± 8.38 mL/100 mg min) was significantly lower than that of the control group (59.87 ± 14.24 mL/100 mg min). Receiver operating characteristic (ROC) curve analysis showed that the area under the curve was 0.77 (95% confidence interval [CI], 0.60, 0.94), and the cutoff value for the diagnosis of CM was 54.83 mL/100 mg min with a sensitivity 84.60% and a specificity 60%.

Conclusion: Imaging evidence of the impaired pain conduction pathway in CM may be related with the decreased perfusion in the PAG, which could be considered as an imaging biomarker for the diagnosis and therapy evaluation.