| Background:Trigeminal neuralgia (TN) is characterized by paroxysmal, electric, lancinating pain in facial areas supplied by the branches of trigeminal nerve, it is a relatively common disease in neurosurgery, the incidence of it is about0.18%, and the incidence has a rising trend with age. Since the pain is extremely intense, unbearable, it affects the patient’s life and work seriously, and reduces the quality of patients’ life. Ultimately, it can lead to suicide. For this persistent illness, scholars have never stopped doing some research. Researchers believe that neurovascular compression is a major cause of TN when a variety of other factors that can cause nerve damage are excluded. With the development of medical imaging, especially high-resolution three-dimensional MRI techniques continue to improve, a variety of different MRI sequences have been used in the evaluation of neurovascular relationships in patients with TN.Purpose:1. To explore the ability of the three-dimensional time-of-flight angiography sequence (3D-TOF MRA), three-dimensional fast imaging employing steady-state acquisition sequence (3D-FIESTA) and contrast-enhanced three-dimensional spoiled gradient-recalled sequence (3D-SPGR) to detect offending vessels surrounding the symptomatic trigeminal nerve in patients with TN preoperatively, and compare detection rates of various sequences. 2. To study the accuracy of the3D-FIESTA sequence and contrast-enhanced3D-SPGR sequence to evaluate the relative position relationship between offending vessels and trigeminal nerve in patients with TN (interior, lateral, superior, inferior).3. To explore the ability of3D-FIESTA sequence in combination with3D-TOF MRA sequence and contrast-enhanced3D-SPGR sequence in combination with3D-TOF MRA sequence to identify the nature of offending vessels (artery or vein) preoperatively.4. To study the best combination of MRI sequences for evaluation of neurovascular relationships in patients with TN.Materials and Methods:1. SubjectsThe subjects were49patients with TN (21male and28female, age range30-77years, mean54.2years) who visited our hospital from December2012to January2014. They had unilateral TN (right side involvement32, left side involvement17), and all had chronic pain and the median symptom duration of5.0years (range1-18years). Before the MRI examinations, all patients had not undergone surgery and the drug therapy is useless. After the MRI examinations, they all were to be treated with microvascular decompression (MVD).2. MRI examinationAll MRI were performed on a3.0Tesla (T) magnetic resonance scanner (Signa; GE Medical Systems, Milwaukee, WI, USA), using8-channel quadrature head coil. Firstly, all patients underwent the conventional head MRI examinations. The sequences used were as follows:T1-weighted imaging, T2-weighted imaging, diffusion-weighted imaging, and T2fluid attenuated inversion recovery. Then, the scanning centered on the pons in the region of the trigeminal nerve. The sequences used were as follows:3D-TOF MRA sequence,3D-FIESTA sequence and contrast-enhanced (gadolinium diethylenetriamine penta-acetic acid, O.lmmol/kg)3D-SPGR sequence. 3. MR image analysisAll the relevant MR images were transmitted to the workstation, and all MR images were independently analyzed by an experienced neuroradiologist, who was blinded to all the clinical details. The relationship between surrounding vessels and the trigeminal nerve was evaluated.(1) To observe whether the presence of vessels around the trigeminal nerve on3D-TOF MRA,3D-FIESTA and contrast-enhanced3D-SPGR images. If the vessels were in close contact with trigeminal nerve, they were regarded as offending vessels.(2) To identify the relative position relationship between offending vessels and trigeminal nerve.On3D-FIESTA and contrast-enhanced3D-SPGR images, the relative position relationship between offending vessels and trigeminal nerve in patients with TN were identified (interior, lateral, superior, inferior).(3) To identify the nature of offending vessels.3D-FIESTA in combination with3D-TOF MRA images were used to identify the nature of offending vessels (artery or vein). If the vessels were demonstrated on both3D-FIESTA images and3D-TOF MRA images, they were arteries; if the vessels were demonstrated only on3D-FIESTA images but not on3D-TOF MRA images, they were veins.Contrast-enhanced3D-SPGR in combination with3D-TOF MRA images were also used to identify the nature of offending vessels (artery or vein) If the vessels were high-signal-intensity on both contrast-enhanced3D-SPGR and3D-TOF MRA images, they were arteries; if the vessels were demonstrated only on contrast-enhanced3D-SPGR images but not on3D-TOF MRA images, they were veins.4. MVD analysisIt was the ultimate criterion that the neurosurgeon was able to see in MVD surgery (offending vessels, the relative position relationship between offending vessels and symptomatic trigeminal nerve, and the nature of offending vessels). All aspects above-mentioned were recorded by the neurosurgeon performing the MVD. 5. Statistical analysisStatistical analysis was performed using Statistical Package for the Social Sciences for Windows version17.0(SPSS, Chicago, IL, USA).The relation in variables was compared usingχ2or the Fisher exact test. The consistency of detection rates between3D-FIESTA sequence and contrast-enhanced3D-SPGR sequence and agreement between preoperative MRI visualization and surgical findings were assessed using the Kappa (K) statistic.The P values of<0.05were considered statistically significant.Result:1. In49patients with TN, surgical findings revealed neurovascular contact in48patients. On the3D-TOF MRA images, contact of the vessel with the symptomatic nerve was detected in38patients, the precision was77.6%, the sensitivity was79.2%and the specificity was100%; On the3D-FIESTA images, contact of the vessel with the symptomatic nerve was detected in48patients, the precision was98.0%, the sensitivity was100%and the specificity was100%; On the contrast-enhanced3D-SPGR images, contact of the vessel with the symptomatic nerve was detected in47patients, the precision was95.9%, the sensitivity was97.9%and the specificity was100%.3D-FIESTA sequence or contrast-enhanced3D-SPGR sequence could detect more offending vessels than3D-TOF MRA sequence (χ21=9.50,P1=0.002;χ22=7.18,P2=0.007), while detection rates of offending vessels between3D-FIESTA sequence and contrast-enhanced3D-SPGR sequence had no statistically significant differences (Fisher exact test,P=1.00), and the consistency of detection rates between them was good (K=0.66).2. As to the relative position relationship between offending vessels and trigeminal nerve, agreement between the results of3D-FIESTA images or contrast-enhanced3D-SPGR images and the findings at surgery was excellent (K1=0.86;K2=0.83).3. As to the nature of offending vessels, agreement between the results of3D-FIESTA in combination with3D-TOF MRA images or contrast-enhanced 3D-SPGR in combination with3D-TOF MRA images and the findings at surgery was excellent (K1=0.95; K2=0.94).Conclusion:1. High-resolution3D-FIESTA sequence and contrast-enhanced3D-SPGR sequence can detect the offending vessels effectively and identify the relative position relationship between offending vessels and symptomatic trigeminal nerve precisely. They can provide comprehensive and useful information for the decision of surgical plan.2. Both3D-FIESTA sequence in combination with3D-TOF MRA sequence and contrast-enhanced3D-SPGR sequence in combination with3D-TOF MRA sequence can identify the nature of offending vessels (artery or vein). However, the former does not need to inject contrast agents, and thus, it can reduce the patients’pain of injecting MR contrast agents and eliminate the potential adverse effects of contrast agents. On the other hand, it can reduce patients’spending. Considering all aspects comprehensively, we come to a conclusion that the best combination is3D-FIESTA sequence in combination with3D-TOF MRA sequence when the patients with TN do MRI examinations preoperatively. |
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