Trigeminal neuralgia: MR imaging features

Magnetic resonance (MR) imaging was used to evaluate the relationship of the cisternal portion of the fifth cranial nerve to surrounding vascular structures in six patients with documented trigeminal neuralgia and in 85 asymptomatic patients. MR imaging clearly demonstrated the course of the fifth nerve from its root entry zone (REZ) to the Meckel cave and its relationship to the surrounding vertebrobasilar system. In the six patients with trigeminal neuralgia, the presence of a vascular structure at the REZ of the fifth nerve was identified. In the 85 asymptomatic patients, examination of 170 trigeminal nerves revealed that 30% had contact between a vascular structure and the fifth nerve at the REZ, but only 2% had actual deformity. These results indicate that although neurovascular contact may be asymptomatic, MR demonstration of a vascular structure at the REZ of the fifth cranial nerve in a patient with trigeminal neuralgia may implicate this as the cause of symptoms, which may influence the treatment of choice. Because of the inherent limitations of computed tomography in the visualization of posterior fossa structures, MR imaging should be considered the initial screening procedure in the assessment of patients with trigeminal neuralgia.     

Trigeminal neuralgia: evaluation of neuralgic manifestation and site of neurovascular compression with 3D CISS MR imaging and MR angiography

PURPOSE: To evaluate three-dimensional (3D) constructive interference in steady-state (CISS) magnetic resonance (MR) imaging and MR angiography with multiplanar reconstruction (MPR) for detection of neurovascular compression (NVC) in patients with trigeminal neuralgia and to evaluate the relationship between clinical symptoms related to trigeminal branches and those related to the site of trigeminal nerve compression. MATERIALS AND METHODS: Fifty-four consecutive patients with trigeminal neuralgia were examined at 3D CISS imaging and MR angiography with a 1.5-T MR system. Original transverse and four reformatted images were used for image interpretation. Vascular contact with the trigeminal nerve at the root entry zone (REZ) was determined, and the nature of the involved vessels was identified. The position of the blood vessel compressing the nerve was classified into cranial, caudal, medial, or lateral sites. Statistical analysis was performed with the chi2 test or the Fisher exact test between two groups and with the chi2 test among more than two groups. RESULTS: In 12 of 15 patients who underwent surgery, the artery that was considered a responsible vessel at 3D CISS imaging and MR angiography was confirmed as such. In the other three patients, the vein was the responsible vessel, which was detected only at 3D CISS imaging. Sixteen (89%) of 18 patients with symptoms related to the maxillary division had NVC at the medial site of the REZ, while 16 (76%) of 21 patients with symptoms related to the mandibular division had NVC at the lateral site (P <.001, chi2 test). CONCLUSION: 3D CISS MR imaging with MPR is useful in the detection of NVC in patients with trigeminal neuralgia, compared with MR angiography. A close relationship was found between the region of neuralgic manifestation and the site of trigeminal nerve compression.     

Trigeminal neuralgia (tic douloureux): MR imaging assessment

The magnetic resonance (MR) imaging studies and clinical records of 29 patients with typical or atypical trigeminal neuralgia (TN) were retrospectively reviewed and compared with the MR studies of 30 patients imaged for reasons unrelated to the fifth cranial nerve. The symptomatic patients were in three groups. Group 1 included those without masses or multiple sclerosis (MS) and those who had not undergone microvascular decompression; group 2, those who underwent microvascular decompression; and group 3, those with masses or MS. Twenty-seven percent of the control group and 57% of the symptomatic patients without masses or MS showed vessel contact with the root entry zone of the preganglionic segment of the fifth cranial nerve. Vessel contact in the symptomatic groups was generally indistinguishable from that seen in the normal group. Fifteen percent of the patients had MS or masses. It is concluded that MR imaging is useful in evaluating patients with TN by facilitating identification of MS or masses but is not helpful in selecting patients with vascular contact who might benefit from microvascular decompression.     

神经血管压迫性三叉神经痛微小神经改变的高空间分辨力扩散张量成像研究

目的利用扩散张量成像与解剖MRI共同定位术前检出神经血管压迫性三叉神经痛(TN)病人三叉神经疑有的微小组织改变。材料与方法研究由机构审查委员会批准,     

A single-blinded pilot study assessing neurovascular contact by using high-resolution MR imaging in patients with trigeminal neuralgia

Objective

To assess the feasibility and utility of high-resolution three-dimensional magnetic resonance angiography (3D MRA) and contrast-enhanced 3D spoiled gradient-recalled imaging (3D SPGRI) for the purpose of visualization of neurovascular contact in trigeminal neuralgia (TN) patients.

Methods

Forty-five patients (25 males, 20 females; age range, 23–82 years; and mean age, 55.67 ± 18.23 years) with unilateral typical TN and 36 control subjects (21 males, 15 females; age range, 25–85 years; mean age, 57.53 ± 19.25 years) underwent high-resolution 3D MRA and contrast-enhanced 3D SPGRI assessment. The images were reviewed by two experienced neuroradiologists who were blinded to the clinical details. The imaging results were compared with the operative findings in all the patients; additionally, the degree of neurovascular contact was compared between the two groups based on MR imaging.

Results

In 45 patients with unilateral typical TN, the use of 3D MRA in conjunction with the contrast-enhanced 3D SPGRI identified neurovascular contact in 40 of the 42 symptomatic nerves; the contact was verified surgically. Based on the surgical findings, the sensitivity and specificity of MR imaging were 95.20% and 100%, respectively. Based on MRI, the compressing vessel (artery, vein) was correctly identified in 32 of the 39 cases verified by microvascular decompression. There was good agreement (K = 0.77; 95% confidence interval, 0.54–0.99) between the position (medial, lateral, superior, and inferior) of the compressing vessel relative to the trigeminal nerve as defined by MR imaging and the surgical findings. The rates of vascular contact with the trigeminal nerve as observed on MRI were 31.94%, 48.89%, and 88.9% in the control subjects, asymptomatic, and symptomatic side of patients, respectively.

Conclusion

The combined use of high-resolution 3D MRA and contrast-enhanced 3D SPGRI is an extremely sensitive and specific technique for demonstrating vascular contact with the trigeminal nerve in TN patients.     

Trigeminal neuropathy: Gd-DTPA enhanced MR imaging

A review of 17 patients with Gd-DTPA enhancing lesions of the trigeminal nerve (6 patients with benign tumors, 4 with inflammatory disease, 7 with malignant tumors) was conducted to determine if contrast enhanced MR imaging is superior to nonenhanced imaging and to identify imaging characteristics that aid in separating benign and malignant disease. Contrast enhanced imaging appears to be superior to nonenhanced imaging in patients with intrinsic fifth nerve lesions. Malignant lesions are suggested by enlarged, enhancing fifth nerves with irregular margins and benign lesions by minimal or no enlargement with smooth margins. Overlap of imaging findings between benign and malignant disease strongly suggests that follow-up imaging and clinical findings are of utmost importance. Gadolinium-enhanced MR imaging of the fifth nerve is recommended in patients with trigeminal sensory or motor deficits as well as those with atypical trigeminal neuralgia.     

MR imaging of the cervical spine: neurovascular anatomy

High-resolution surface-coil MR imaging reveals intricate anatomic detail of the cervical spinal canal and its neurovascular contents. Appreciation of the normal neurovascular anatomy provides a scientific foundation for the detection of disease. Sagittal, axial, and oblique MR images of normal subjects were correlated with comparable anatomic sections obtained with a cryomicrotome whole-organ sectioning technique. The anterior epidural venous plexus is a prominent structure in the cervical spinal canal and was consistently identified both with cryomicrotomy and with MR in sagittal and axial planes. Epidural veins can be displaced and distorted in patients with cervical disk disease. Nerve roots including dorsal and ventral rootlets were consistently identified on axial images coursing through the subarachnoid space. Oblique-plane imaging showed nerve roots "en face" in their respective foramina; this may be a useful imaging technique in the diagnosis of nerve root impingement.     

Image quality and focal lesion detection on T2-weighted MR imaging of the liver: comparison of two high-resolution free-breathing imaging techniques with two breath-hold imaging techniques

PURPOSE: To evaluate image quality and accuracy for the detection of focal hepatic lesions depicted on T2-weighted images obtained with two high-resolution free-breathing techniques (navigator-triggered turbo spin-echo [TSE] and respiratory-triggered TSE) and two standard-resolution breath-hold techniques (breath-hold TSE with restore pulse and half-Fourier acquisition single-shot TSE [HASTE]). MATERIALS AND METHODS: Our institutional review board approved this study, and written informed consent was obtained from all patients. Two readers independently reviewed 200 T2-weighted imaging sets obtained with four sequences in 50 patients. Both readers identified all focal lesions in session 1 and only solid lesions in session 2. The readers' confidence was graded using a scale of 1-4 (1 or= 95%). The diagnostic accuracies of the four MR sequences were evaluated using the free-response receiver operating characteristic (ROC) method. Region-of-interest (ROI) measurements were performed for the mean signal intensity (SI) in the liver, spleen, hepatic lesions, and background noise. RESULTS: The accuracy of navigator-triggered TSE and respiratory-triggered TSE was superior to that of breath-hold TSE with restore pulse and HASTE for the detection of all focal or solid hepatic lesions. The mean lesion-to-liver contrast-to-noise ratio (CNR) of solid lesions in navigator-triggered (P < 0.001) and respiratory-triggered TSE (P < 0.005) was significantly higher than that in HASTE. CONCLUSION: High-resolution, free-breathing, T2-weighted MRI techniques can significantly improve the detectability of focal hepatic lesions and provide higher lesion-to-liver contrast of solid lesions compared to breath-hold techniques.     

Trigeminal nerve: anatomic correlation with MR imaging

Through correlation with cryomicrotic sections, the appearance of the trigeminal nerve and its branches on magnetic resonance images is described in healthy individuals and in patients with tumors involving this nerve. Coronal images are best for defining the different parts of the nerve and for making a side-to-side comparison. Sagittal images are useful to demonstrate tumors involving the gasserian ganglion.     

Diagnosis of recurrent hyperparathyroidism: comparison of MR imaging and other imaging techniques

Several reports have indicated good results with MR imaging of hyperparathyroidism. However, its use in recurrent hyperparathyroidism has not been assessed separately. Thirty patients with recurrent hyperparathyroidism were evaluated by MR with both T1- and T2-weighted images. Twenty-six and 23 of these patients, respectively, also had thallium-201 scintigraphy and high-resolution sonography. For the 28 patients who eventually had surgical exploration and histologic evidence of adenoma (21 cases) or hypoplasia (seven cases), MR accurately located abnormal parathyroid glands in 75% evaluated prospectively and 89% evaluated retrospectively. Scintigraphy located 68% prospectively and 76% retrospectively. Sonography detected 57% prospectively and 67% retrospectively. For patients undergoing three studies, the prospective and retrospective detection rate was significantly better (p less than .05) for MR compared with sonography but was not significantly different for MR and scintigraphy. MR detected three of four mediastinal adenomas evaluated prospectively and retrospectively. One false-positive case was seen with MR, one with scintigraphy, and one with sonography. Thus, MR can be used to locate abnormal parathyroid tissue at a rate equal to or better than scintigraphy or sonography.     

Real-time interactive duplex MR measurements: application in neurovascular imaging

OBJECTIVE: Real-time interactive duplex MR imaging is a new phase-contrast MR imaging technique that enables the quantification and display of flow velocities in real time without the need for cardiac gating. We investigated the feasibility and reliability of the technique to assess hemodynamic information both in vitro and in vivo in the carotid arteries and in the venous sinuses. SUBJECTS AND METHODS: Real-time interactive duplex MR measurements (TR/TE, 53/27; flip angle, 90 degrees; encoding velocity, 100 or 150 cm/sec) were performed in vitro with a steady-flow phantom and in 10 healthy volunteers in whom common and internal carotid artery velocities were measured. In eight volunteers, velocity measurements were also performed in the superior sagittal sinus during both normal breathing and hyperventilation. Time-velocity plots were analyzed qualitatively and quantitatively and compared with findings from conventional segmented k-space phase-contrast MR imaging and Doppler sonography. RESULTS: Velocity determinations for real-time duplex MR and conventional phase-contrast MR imaging showed an in vitro correlation of 0.99 and an in vivo correlation of 0.83 (carotid arteries) and 0.76 (venous sinus). Velocity measurements in the carotid arteries with real-time MR imaging were significantly lower than those obtained with conventional phase-contrast MR (averaged, 7.8%; p = 0.003) or sonography (23.7%, p < 0.001), likely because of volume averaging. Small but significant velocity changes occurring in the venous sinus during hyperventilation were reliably identified with both MR techniques. CONCLUSION: Real-time interactive duplex MR imaging can be effectively applied in neurovascular imaging to obtain hemodynamic information.     

Perfusion-sensitive MR imaging of gliomas: comparison between gradient-echo and spin-echo echo-planar imaging techniques

BACKGROUND AND PURPOSE: The different sensitivities to vessel size of gradient-echo echo-planar imaging (GE-EPI) and spin-echo EPI (SE-EPI) might indicate the relative cerebral blood volumes (rCBVs) of different tumor sizes. The techniques of GE-EPI and SE-EPI were compared for detecting low- versus high-grade gliomas. METHODS: Six patients with low-grade gliomas and 19 patients with high-grade gliomas underwent two perfusion-sensitive MR procedures, one produced by a GE- and the other by an SE-EPI technique. Maximum rCBV ratios normalized with rCBV of contralateral white matter were calculated for evaluation. P <.05 was considered statistically significant. RESULTS: Maximum rCBV ratios of high-grade gliomas obtained with the GE-EPI technique (mean, 5.0 +/- 2.9) were significantly higher than those obtained with the SE-EPI technique (mean, 2.9 +/- 2.3) (P =.02). Maximum rCBV ratios of low-grade gliomas obtained with the GE-EPI technique (mean, 1.2 +/- 0.7) were almost equal to those obtained with the SE-EPI technique (mean, 1.2 +/- 0.6), and there was no significant difference (P =.66). The difference in the maximum rCBV ratios between the low- and high-grade gliomas reached significance when obtained with the GE-EPI technique (P =.01). CONCLUSION: The GE-EPI technique seems more useful for detecting low- versus high-grade gliomas than the SE-EPI technique.     

Optimizing joint imaging: MR imaging techniques

For optimizing MR of the joints, a sophisticated knowledge of MR system hard-and software condition, and coil technologies, sequence and contrast preparation techniques, and the use of paramagnetic contrast agents is necessary. This review article discusses the basic principles of the appropriate use of surfacecoilsas well as the different conventional and fast imagingsequences, including three-dimensional (3D)MR imaging. In addition, the applications of contrast agents as well as the most important contrast prepaation techniques are reviewed.     

Detection and characterization of metastatic cervical adenopathy by MR imaging: comparison of different MR techniques

Thirty-five patients scheduled to undergo a neck dissection for squamous cell carcinoma of the head and neck were evaluated preoperatively by magnetic resonance (MR) imaging. Axial and occasionally sagittal and coronal images were obtained. To define the most reliable technique to detect cervical lymph node metastasis, we compared several MR pulse sequences with and without Gd-DTPA administration to histopathologic findings in the neck dissection specimens. T1-weighted spin echo combined with T2-weighted gradient recalled echo (GE) sequences were found to be more useful than any other combination of pulse sequences in localizing lymph nodes. On T2-weighted GE images, lymph nodes were depicted with intermediate to high signal intensity in contrast to low signal muscular and fatty tissue. Gadolinium DTPA enhanced T1-weighted GE images reliably depict central lymph node necrosis, the most specific criterion for lymph node metastasis.     

Ultrasound-guided injection for MR arthrography of the hip: comparison of two different techniques

Objective

The purpose of this study was to prospectively evaluate the two different ultrasound-guided injection techniques for MR arthrography of the hip.

Materials and methods

Fifty-nine consecutive patients (21 men, 38 women) referred for MR arthrographies of the hip were prospectively included in the study. Three patients underwent bilateral MR arthrography. The two injection techniques were quantitatively and qualitatively compared. Quantitative analysis was performed by the comparison of injected contrast material volume into the hip joint. Qualitative analysis was performed with regard to extraarticular leakage of contrast material into the soft tissues. Extraarticular leakage of contrast material was graded as none, minimal, moderate, or severe according to the MR images. Each patient rated discomfort after the procedure using a visual analogue scale (VAS).

Results

The injected contrast material volume was less in femoral head puncture technique (mean 8.9?±?3.4?ml) when compared to femoral neck puncture technique (mean 11.2?±?2.9?ml) (p?<?0.05). The chi-squared test showed significantly more contrast leakage by femoral head puncture technique (p?<?0.05). Statistical analysis showed no difference between the head and neck puncture groups in terms of feeling of pain (p?=?0.744) or in the body mass index (p?=?0.658) of the patients.

Conclusion

The femoral neck injection technique provides high intraarticular contrast volume and produces less extraarticular contrast leakage than the femoral head injection technique when US guidance is used for MR arthrography of the hip.