Trigeminal neuralgia is characterized by facial pain that may be sudden, intense, and recurrent. Our aim was to investigate microstructural tissue changes of the trigeminal nerve in patients with trigeminal neuralgia resulting from neurovascular compression by diffusion tensor imaging, and to test the predictive value of diffusion tensor imaging for determining outcomes after radiofrequency rhizotomy. Forty-three patients with trigeminal neuralgia were recruited, and diffusion tensor imaging was performed before radiofrequency rhizotomy. By selecting the cisternal segment of the trigeminal nerve manually, we measured the volume of trigeminal nerve, fractional anisotropy, apparent diffusion coefficient, axial diffusivity, and radial diffusivity. The apparent diffusion coefficient and mean value of fractional anisotropy, axial diffusivity, and radial diffusivity were compared between the affected and normal side in the same patient, and were correlated with pre-rhizotomy and post-rhizotomy visual analogue scale pain scores. The results showed the affected side had significantly decreased fractional anisotropy, increased apparent diffusion coefficient and radial diffusivity, and no significant change of axial diffusivity. The volume of the trigeminal nerve on affected side was also significantly smaller. There was a trend of fractional anisotropy reduction and visual analogue scale pain score reduction (P = 0.072). The results suggest that demyelination without axonal injury, and decreased size of the trigeminal nerve, are the microstructural abnormalities of the trigeminal nerve in patients with trigeminal neuralgia caused by neurovascular compression. The application of diffusion tensor imaging in understanding the pathophysiology of trigeminal neuralgia, and predicting the treatment effect has potential and warrants further study.

Background Diffusion‐weighted imaging (DWI) has shown promise to screen for breast cancer without a contrast injection, but image distortion and low spatial resolution limit standard single‐shot DWI. Multishot DWI methods address these limitations but introduce shot‐to‐shot phase variations requiring correction during reconstruction. Purpose To investigate the performance of two multishot DWI reconstruction methods, multiplexed sensitivity encoding (MUSE) and shot locally low‐rank (shot‐LLR), compared to single‐shot DWI in the breast. Study Type Prospective. Population A total of 45 women who consented to have multishot DWI added to a clinically indicated breast MRI. Field Strength/Sequences Single‐shot DWI reconstructed by parallel imaging, multishot DWI with four or eight shots reconstructed by MUSE and shot‐LLR, 3D T2‐weighted imaging, and contrast‐enhanced MRI at 3T. Assessment Three blinded observers scored images for 1) general image quality (perceived signal‐to‐noise ratio [SNR], ghosting, distortion), 2) lesion features (discernment and morphology), and 3) perceived resolution. Apparent diffusion coefficient (ADC) of the lesion was also measured and compared between methods. Statistical Tests Image quality features and perceived resolution were assessed with a mixed‐effects logistic regression. Agreement among observers was estimated with a Krippendorf's alpha using linear weighting. Lesion feature ratings were visualized using histograms, and correlation coefficients of lesion ADC between different methods were calculated. Results MUSE and shot‐LLR images were rated to have significantly better perceived resolution (P < 0.001), higher SNR (P < 0.005), and a lower level of distortion (P < 0.05) with respect to single‐shot DWI. Shot‐LLR showed reduced ghosting artifacts with respect to both MUSE (P < 0.001) and single‐shot DWI (P < 0.001). Eight‐shot DWI had improved perceived SNR and perceived resolution with respect to four‐shot DWI (P < 0.005). Data Conclusion Multishot DWI enables increased resolution and improved image quality with respect to single‐shot DWI in the breast. Shot‐LLR reconstructs multishot DWI with minimal ghosting artifacts. The improvement of multishot DWI in image quality increases with an increased number of shots. Level of Evidence 2 Technical Efficacy Stage 2

Background Trigeminal neuralgia (TN) is characterized by facial pain that may be sudden, intense, and recurrent. Neurosurgical interventions, such as radiofrequency rhizotomy, can relieve TN pain, but their mechanisms and effects are unknown. The aim of the present study was to investigate the microstructural tissue changes of the trigeminal nerve (TGN) in patients with TN after they underwent radiofrequency rhizotomy. Methods Thirty-seven patients with TN were recruited, and diffusion tensor imaging was obtained before and two weeks after radiofrequency rhizotomy. By manually selecting the cisternal segment of the TGN, we measured the volume of the TGN, fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD). The TGN volume and mean value of the DTI metrics of the post-rhizotomy lesion side were compared with those of the normal side and those of the pre-rhizotomy lesion side, and they were correlated to the post-rhizotomy visual analogue scale (VAS) pain scores after a one-year follow-up. Results The alterations before and after rhizotomy showed a significantly increased TGN volume and FA, and a decreased ADC, AD, and RD. The post-rhizotomy lesion side showed a significantly decreased TGN volume, FA, and AD compared with the normal side; however, no significant difference in the ADC and RD were found between the groups. The TGN volume was significantly higher in the non-responders than in the responders ( P = 0.016). Conclusion Our results may reflect that the effects of radiofrequency rhizotomy in TN patients include axonal damage with perineural edema and that prolonged swelling associated with recurrence might be predicted by MRI images. Further studies are necessary to understand how DTI metrics can quantitatively represent the pathophysiology of TN and to examine the application of DTI in the treatment of TN.

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