A Radiomics Study Of The Meckel Cave And Screening For Primary Trigeminal Neuralgia

Objective:Neurovascular contact(NVC)is the main factor of primary trigeminal neuralgia(PTN),but there is still PTN without apparent cause.Many studies have proved that the morphological and pathological changes of trigeminal nerve in root entry zone are related to PTN,but Meckel cave(MC)lacks in-depth study.Firstly,in this study,the MC,s morphology and texturology to PTN and healthy controls(HC)were analyzed by radiomics to explore the cause of PTN.Secondly,this study was performed amongst PTN patients with neurovascular contact(NVC)to investigate the association of the demographic and radiologic factors with TN occurrence,and develop a screening tool for TN/TN-affected nerves based on the factors associated with it.Methods:We studied the MRI data of 115 patients with PTN and 46 HC group.The balanced turbo field echo and enhanced T1 high-resolution isotropic volume excitation data of 3.0T MRI were recorded.Bilateral MC was modeled by 3Dslicer software,and 1)13 morphological characteristics of MC were analyzed by radiomics method,as well as the analysis of the correlation between the two groups,2)94 texture characteristics of MC were analyzed by radiomics method,as well as the analysis of the correlation in PTN group.PTN patients were recruited,and 121 trigeminal nerves with NVC were derived from them.Based on MRI sequences,including balanced turbo field echo and enhanced T1 high-resolution isotropic volume excitation,radiologic factors for each nerve,from the offending vessel to the presence of nerve displacement,were identified by a neuroradiologist and a neurosurgeon.Demographic and clinical data were obtained from clinical notes.Logistic regression was performed to assess the association of the factors/variables with PTN occurrence(i.e.,affected vs.unaffected nerves).Results:1)The right side incidence rate of group PTN was higher than that of left side(P<0.01).2)MC of HC group had asymmetry in morphology.In shape,the right MC is flatter than the left MC(Sphericity&Flatness:right<left(P<0.01)),and the right MC is larger than the left MC(Maximum 3D Diameter&Maximum 2D Diameter Column:right>left(P<0.05),Least Axis Length:right<left(P<0.05)).3)MC of PTN group had asymmetry in morphology.In shape,the right MC is flatter than the left MC(Sphericity&Flatness:right<left(P<0.01)),and the right MC is larger than the left MC(Surface Area,Maximum 3D Diameter,Maximum 3D Diameter:right>left(P<0.05),Maximum 2D Diameter Slice/Column/Row:right>left(P<0.05),Least Axis Length:right<left(P<0.05)).4)By analyzing the Flatness feature of MC,it was found that the affected side of PTN was lower than that of unaffected side(P<0.05),the right MC of HC was lower than the left MC(P<0.01),the right MC of PTN was lower than the left MC(P<0.01),the affected side MC of left PTN with no NVC on both side was lower than that of unaffected side(P<0.051),the affected side MC of right PTN with no NVC on both side was lower than that of unaffected side(P<0.05).The flatness of HC and PTN was positively correlated with the Least Axis Length(P<0.01)and negatively correlated with the Major Axis Length(P<0.01).5)The NGTDM-contract texture feature of MC was related to PTN,and the unaffected side was greater than the affected side(P<0.05).6)Three factors/variables were significantly(P≤0.05)associated with PTN occurrence amongst patients with NVC:nerve laterality,vertebral artery(VA)involvement,and the presence of nerve displacement.The nerves with VA involvement,those on the right side,and those with nerve displacement exhibited a significantly higher likelihood/odd of being affected by PTN,compared to those without VA involvement,those on the left side,and those without nerve displacement,respectively.7)Based on these factors/variables,a screening tool/nomogram with acceptable accuracy was established(C-statistic/AUC=0.80).Conclusion:1)By providing a method to analyze the morphology of MC,it is found that there is asymmetry in the morphology of MC on both sides of PTN and HC group.Therefore,it can be inferred that flatness of MC may be a cause of PTN.2)The NGTDM-contract texture features of MC in patients with PTN were correlated with PTN.This texture feature may indicate trigeminal nerves degeneration/atrophy in MC,resulting in flattening in morphological features.The NGTDM-contract of texture feature and flatness of morphological feature confirm each other and provide another angle for clinical imaging to interpret MC and infer PTN.3)This study revealed an association of the three radiologic factors with PTN occurrence.A screening tool for PTN/TN-affected nerves was established based on them.4)The findings may lay a foundation for an improvement of the diagnosis and clinical management of PTN.