3D Constructive Interference In Steady State Research Articles

The effect of bony cochlear nerve canal (BCNC) diameter on the degree of sensorineural hearing loss.

This study investigated the correlation between the diameter of the bony cochlear nerve canal (BCNC), as determined by Temporal bone CT, and MRI findings of cochlear nerves (CN) in children with sensorineural hearing loss (SNHL). A prospective study design was followed. Radiological data (Temporal bone CT and MRI) of fifty children with sensorineural hearing loss (age <18y) were included in the study. All patients (100 ears) underwent routine MRI protocol in addition to 3D CISS (3-D constructive interference in steady state). Based on CT findings, the BCNC was classified according to its diameter into three groups; group 1 (<1.4mm), group 2 (1.4-2.0mm), and group 3 (>2.0mm). A significant difference between the three groups at degrees of SNHL (p<0.001) was observed. Significant difference (p<0.001) was also observed in the mean level of pure tone audiometry (PTA) average in group 1 compared to group 2. The CN was absent in 20 ears of group 1 CT results (29%), CN hypoplasia was noticed in 40 ears of group 1 CT (58%). However, CN was present in 9 ears of group 1 CT (13%), while in group 2 and 3, CN was present in 100% of the cases (27, and 4 ears, respectively, p<0.001). MRI and CT imaging are valuable in the diagnosis of SNHL in children. Moreover, with BCNC stenosis, there was a high probability of CN aplasia or hypoplasia.

Comparison of 3D constructive interference in steady state (CISS) and T2 sampling perfection with application optimized contrasts using different flip angle evolution MR imaging of the intracranial trigeminal nerve and central skull base neuroforamina.

Due to surgical advancements, the accurate detection of perineural disease spread has become increasingly important in the management and prognostication of head and neck cancers, though MR evaluation has thus far been limited by technical and logistic challenges. The purpose of this study was to specifically evaluate the relative capability of 3D CISS and 3D T2-SPACE imaging to delineate the proximal intracranial divisions of the normal trigeminal nerve, an area important in determining the resectability of intracranial perineural disease. A single center HIPAA-compliant, IRB approved retrospective review of 40 patients with clinical temporal bone/internal auditory canal MR imaging was conducted. 20 patients with 3D CISS images and 20 patients with 3D T2-SPACE images met inclusion criteria. Two radiologists scored the sequences on a 3-point scale based on ability to visualize anatomic structures surrounding the trigeminal nerve in Meckel's cave, intracranial trigeminal divisions, skull base neuroforamina, and proximal extracranial mandibular division. The following anatomic locations scored significantly better in the T2-SPACE sequence compared to the CISS sequence for both raters: intracranial V3 (p < .05), foramen ovale (p < .05), and extracranial V3 (p < .01). The average scores for the anterior Meckel's cave and foramen rotundum were higher for the T2-SPACE sequence, although not significantly. Percent interobserver agreement ranged from 50 to 90% and 65-100% for the different anatomic locations on the CISS and T2-SPACE sequences, respectively. 3D T2-SPACE was found to be superior to 3D CISS in the evaluation of the distal intracranial and extracranial portions of the normal trigeminal nerve.

English

English

Superficial Siderosis of the Central Nervous System: Neurotological Findings Related to Magnetic Resonance Imaging.

To compare the neurotological results of five patients suffering from progressive hearing loss and ataxia due to superficial siderosis (SS) with the magnetic resonance imaging (MRI) findings. Retrospective case review. Primary and hospital care center. Five adult patients with neurotological symptoms of SS underwent MRI with acquisition of our temporal bone protocol including 3D-constructive interference in steady state (3D-CISS) and susceptibility-weighted imaging (SWI). All patients underwent a complete neurotological examination, the results of which were compared with the imaging findings. Cochleovestibular deficits were present in all five patients as determined by uni- or bilateral bithermal caloric testing and/or video head impulse tests. Sacculocollic reflex was present with increased P1 and N1 latencies on both sides in all patients. MRI revealed an extensive hypointense SWI signal outlining the surface of the brain and the VIIIth cranial nerve in all five patients. Desynchronization of the brainstem auditory evoked potentials (BAEP) and partial or complete absence of the visual suppression of vestibulo-ocular reflex during the pendular rotatory test was particularly consistent with the lesions of the cochleovestibular nerves as well as the cerebellar atrophy seen on MRI. The MRI results with SWI were related to neurotological findings in patients suffering from sensorineural deafness with ataxia due to SS. Our findings support the integration of the SWI and 3D-CISS sequences into the MRI protocol for all patients referred for evaluation of the extent of SS.

Radiosurgery of vestibular schwannoma: prognostic factors for hearing outcome using 3D-constructive interference in steady state (3D-CISS).

Stereotactic radiosurgery (SRS) is an effective treatment for vestibular schwannoma (VS). Three-dimensional (3D) constructive interference in steady state (CISS) is the preferred magnetic resonance imaging (MRI) sequence for evaluating signal changes in the inner ear endolymph. Previous studies demonstrated acorrelation between pretreatment cochlear signal intensity in 3D-CISS and posttherapeutic hearing outcomes. The purpose of our study was to compare 3D-CISS sequences before and after primary SRS of unilateral VSs to evaluate the effect of radiosurgery on the 3D-CISS signal intensities of cochlea and sacculus/utriculus. We retrospectively reviewed 47patients with unilateral VS treated with SRS. The neuroradiological MRI datasets were analysed to evaluate the signal intensity of the inner ear structure, tumour size, Koos grade, tumour volume, and infiltration of the cochlear aperture before therapy and at follow-up. The differences in these signal intensities before SRS and at follow-up were correlated with clinical symptoms, cochlear radiation dose, tumour volume and infiltration of the cochlear aperture. No differences were found between signal intensities in cochlea and utriculus/sacculus before and after SRS and no correlation with clinical symptoms, cochlear radiation dose, tumour volume, Koos grade or infiltration of the cochlear aperture (all p > 0.05). Our study supports the theory of acomplex interaction causing alteration of the endolymph protein concentration and not adirect dependency on the SRS. Use of modern dosing schemes will have apositive impact on clinical outcome with preservation of hearing in patients with VS.

Additive Value of 3T 3D CISS Imaging to Conventional MRI for Assessing the Abnormal Vessels of Spinal Dural Arteriovenous Fistulae.

Introduction:We investigated the additive value of the 3T 3D constructive interference in steady state (CISS) sequence to conventional MRI for the evaluation of spinal dural arteriovenous fistulae (SDAVF).Materials and Methods:We included 16 consecutive patients (15 men, 1 woman; age range 42–81 years; mean 64 years) with SDAVF who underwent 3T MRI and digital subtraction angiography (DSA) before treatment. Two neuroradiologists independently evaluated the presence of abnormal vessels on 3D CISS-, T2- and T1-weighted images (T1WI, T2WI), and contrast-enhanced T1WI using a 3-point grading system. Interobserver agreement was assessed by calculating the κ coefficient.Results:The SDAVF site was the cervical region in one patient, the thoracic region in 12 patients, the lumbar region in two, and the sacral region in one. For the visualization of abnormal vessels, the mean score was significantly higher for 3D CISS than the other sequences (P < 0.05). In 12 of 16 cases (75%) both readers made definite positive findings on additional 3D-CISS images. Interobserver agreement was excellent for 3D CISS images (κ = 1.0), good for T1WI (κ = 0.78; 95% confidence interval [CI] 0.54–1.00) and T2WI (κ = 0.74; 95% CI 0.48–1.00) and moderate for contrast-enhanced T1WI (CET1WI) (κ = 0.50; 95% CI 0.21–0.80).Conclusion:For the assessment of abnormal vessels of SDAVF, the 3T 3D CISS sequence adds value to conventional MRI.

The value of MRI 3D-CISS sequence in trigeminal neuralgia-related diseases

Objective To explore 3D constructive interference insteady state sequence value of related diseases in trigeminal neuralgia. Methods A retrospective analysis of 62 cases of trigeminal neuralgia as the main symptoms of patients with brain magnetic resonance imaging (MRI) routine scan and 3D constructive interference insteady state (3D-CISS) sequence images, of which 12 cases were enhanced scan, comparative analysis of MRI 3D-CISS sequence and conventional sequence of trigeminal nerve. The lesion showed the condition and was compared with the outcome of the operation. Trigeminal neuralgia-related lesions mainly included the trigeminal nerve brain pool around the vascular compression or transition, solid tumors and tumor-like lesions. Results Preoperative MRI 3D-CISS sequence was used to diagnose the vascular compression or metastasis of the trigeminal nerve pool segment in 46 cases. Forty-five patients were found to be responsible blood vessels. The 3D-CISS sequence showed 95.83% coincidence with surgical exploration. The routine sequence could not show the trigeminal The brain around the brain was forced or pushed. 3D-CISS sequence showed eight cases of solid tumors, routine scan showed six cases of solid tumors. Tumor-like lesions were shown in 6 cases of MRI3D-CISS sequences and routine plain scan sequences. The sensitivity of 3D-CISS sequence to trigeminal neuralgia-related disease was 96.77%, and the sensitivity of MRI routine scan to trigeminal neuralgia was only 19.35%. There was significant difference in the sensitivity of 3D-CISS sequence and conventional plain scan sequence to trigeminal neuralgia-related diseases (P<0.01). Conclusions MRI 3D-CISS sequence has a significant advantage in trigeminal neuralgia-related disease, and patients with trigeminal neuralgia should routinely use 3D-CISS sequences. Key words: Magnetic resonance imaging; Trigeminal neuralgia/CO/DI

Analogous Three-Dimensional Constructive Interference in Steady State Sequences Enhance the Utility of Three-Dimensional Time of Flight Magnetic Resonance Angiography in Delineating Lenticulostriate Arteries in Insular Gliomas: Evidence from a Prospective Clinicoradiologic Analysis of 48 Patients

Three-dimensional (3D) time of flight (TOF) imaging is the current gold standard for noninvasive, preoperative localization of lenticulostriate arteries (LSAs) in insular gliomas; however, the utility of this modality depends on tumor intensity. Over a 3-year period, 48 consecutive patients with insular gliomas were prospectively evaluated. Location of LSAs and their relationship with the tumor were determined using a combination of contrast-enhanced coronal 3D TOF magnetic resonance angiography and coronal 3D constructive interference in steady state (CISS) sequences. These findings were analyzed with respect to extent of tumor resection and early postoperative motor outcome. Tumor was clearly visualized in 29 (60.4%) patients with T1-hypointense tumors using 3D TOF and in all patients using CISS sequences. Using combined 3D TOF and CISS, LSA-tumor interface was well seen in 47 patients, including all patients with T1-heterointense or T1-isointense tumors. Extent of resection was higher in the LSA-pushed group compared with the LSA-encased group. In the LSA-encased group, 6 (12.5%) patients developed postoperative hemiparesis; 2 (4.2%) cases were attributed to LSA injury. Contrast-enhanced 3D TOF can delineate LSAs in almost all insular gliomas but is limited in identifying the LSA-tumor interface. This limitation can be overcome by addition of analogous CISS sequences that delineate the LSA-tumor interface regardless of tumor intensity. Combined 3D TOF and 3D CISS is a useful tool for surgical planning and safer resections of insular tumors and may have added surgical relevance when included as an intraoperative adjunct.

Value of combined three dimensional constructive interference in steady state with phase-contrast MR in diagnosis of hydrocephalus children

Objective To investigate the value of combined 3D-constructive interference in steady state(3D-CISS) with phase-contrast MR(PC-MR) in diagnosis of hydrocephalus children. Methods We collected retrospectively 28 children with hydrocephalus who caused by obstructive membranes.They all underwent MR imaging examination with a 1.5 T consisting of 3D-CISS, conventional sequences and PC-MR. With the result of surgery and CT cisternography as gold standard,we analysised different sequence in the diagnosis of membranous obstruction. The results of obstructive were analysed by χ2 test between 3D-CISS combined with PC-MR and conventional sequences. Results The study included 28 children, of whom 16 showed obstructive membranes in CSF pathways of ventricle and 12 displayed obstructive membranes in CSF pathways of cistern. Conventional sequences diagnosed obstructive membranes of 15 children, and obstructive membranes of 11 children were consistent with gold standard, and 4 cases were false positive. The 3D-CISS diagnosed obstructive membranes of 40, and 12 cases were false positive.There were significant difference between 3D-CISS combined with PC-MR and conventional sequence about obstructive membranes diagnosis of CSF pathways(χ2=24.410, P=0.001). Conclusions Making use of jointing 3D-CISS sequence and PC-MR sequence successively, and we can diagnose the position of obstructive membrane for hydrocephalus, which can be helpful to select a perfect surgical approach. Key words: Hydrocephalus; Magnetic resonance imaging

Applications of 3D CISS sequence for problem solving in neuroimaging

Three-dimensional (3D) constructive interference in steady state (CISS) is a gradient-echo MRI sequence that is used to investigate a wide range of pathologies when routine MRI sequences do not provide the desired anatomic information. The increased sensitivity of the 3D CISS sequence is an outcome of the accentuation of the T2 values between cerebrospinal fluid (CSF) and pathological structures. Apart from its well-recognized applications in the evaluation of the cranial nerves, CSF rhinorrhea and aqueduct stenosis, we have found the CISS sequence to be useful for the cisternal spaces, cavernous sinuses and the ventricular system, where it is useful for detecting subtle CSF-intensity lesions that may be missed on routine spin-echo sequences. This information helps in the management of these conditions. After a brief overview of the physics behind this sequence, we illustrate its clinical applications with representative cases and discuss its potential role in imaging protocols.

Study of the Anatomical Variations of Vertebral Artery in C2 Vertebra With Magnetic Resonance Imaging and Its Application in the C1–C2 Transarticular Screw Fixation

Use of magnetic resonance imaging (MRI) with Constructive Interference in Steady State (CISS) sequence and isometric voxels to demonstrate the anatomic variations of vertebral artery in C2 vertebra. To determine the transarticular screw trajectory on CISS MRI and to identify patients with anatomic variations of vertebral artery in C2 vertebra. Atlantoaxial transarticular screw fixation has been reported to be biomechanically superior to other posterior techniques for atlantoaxial arthrodesis. Vertebral artery injury can be associated with catastrophic sequelae. Anatomic variation of vertebral artery is well recognized and computed tomography scan is the traditional preoperative assessment. However, no report has evaluated the use of MRI in preoperative assessment for the screw trajectories and the anatomic variation of vertebral artery. The 3-dimensional (3D) CISS MRI with isometric voxels was performed in 30 local Chinese patients. The 3D reconstruction images were created to determine the proposed screw trajectories and their relationship with the vertebral arteries. In 12 patients (40%), the vertebral arteries were lying within the screw trajectories prohibiting transarticular screw fixation on at least one side. Bilateral variations with high risk of vertebral artery injuries were found in 6 patients. The remaining 6 patients had unilateral variations prohibiting the insertion of transarticular screws on one side. The 3D CISS MRI with isometric voxels is a safe and simple imaging technique to outline the vertebral arteries in C2. Reconstruction images are easily created and undistorted. It is one of the useful imaging in preoperative planning of transarticular screw fixation and determination of anatomy of vertebral artery.

Anatomical features of the cisternal segment of the oculomotor nerve: neurovascular relationships and abnormal compression on magnetic resonance imaging

The object of this study was to assess the detailed anatomical features and vascular relationships of the cisternal segment of the oculomotor nerve, and to assess the utility of MR imaging in oculomotor nerve palsy caused by abnormal compression related to arteries and tumors. The anatomy of the oculomotor nerve was depicted using 3D Fourier transformation constructive interference in steady-state (CISS) MR imaging in 196 volunteers (392 total nerves), in 9 patients with paralysis of the oculomotor nerve, and in 1 preoperative patient with cholesteatoma in the pontine cistern. The vessels adjacent to the oculomotor nerve were detected and compared using 3D time-of-flight MR imaging. The 3D CISS multiplanar reconstruction (MPR) images of the oculomotor nerve in cadavers and in specimens from the cadavers were used to verify the oculomotor nerve shown in the 196 patients. The images were assessed with respect to the demonstration of the oculomotor nerve, the optimal display angles on MPR images, the visualized length of the nerve, neurovascular relationships, and abnormal compression caused by arteries and tumors. Three-dimensional CISS MR imaging depicted the cisternal segment of the oculomotor nerve with certainty in 100% of the patients in the transverse, sagittal, and coronal planes. Three-dimensional CISS imaging of the oculomotor nerve in 196 volunteers revealed similar results corresponding to 3D CISS MPR images of cadavers and cadaver specimens. The maximum visualized length of the oculomotor nerve was 14.61 +/- 2.33 mm. The angle between the oculomotor nerve and the median sagittal plane was 24.48 +/- 4.57 degrees on the left and 24.48 +/- 5.07 degrees on the right. The posterior cerebral artery was observed to contact the oculomotor nerve in 216 (55.1%) of 392 nerves, and the superior cerebellar artery was observed to contact the oculomotor nerve in 231 (58.9%) of 392 nerves. The abnormal nerve compression in 9 patients with paralysis of the oculomotor nerve was displayed well in all patients. The adjacent relationship of the oculomotor nerve in 1 preoperative patient with cholesteatoma in the pontine cistern was also demonstrated clearly. Use of 3D CISS sequences and 3D time-of-flight sequences enables accurate identification of the cisternal segment of the oculomotor nerve, neurovascular relationships, and abnormal compression caused by arteries and tumors.

Is All “Communicating” Hydrocephalus Really Communicating? Prospective Study on the Value of 3D-Constructive Interference in Steady State Sequence at 3T

3D-constructive interference in steady state (3D-CISS) sequence has been used to assess the CSF pathways. The aim of this study was to investigate the additive value of 3D-CISS compared with conventional sequences in the diagnosis of obstructive membranes in hydrocephalus. A total of 134 patients with hydrocephalus underwent MR imaging examination with a 3T unit consisting of turbo spin-echo, 3D-CISS, and cine phase-contrast (cine PC) sequences. 3D-CISS was used to assess obstructive membranes in CSF pathways compared with other sequences. Cine PC, follow-up imaging, and surgical findings were used to confirm obstructive membranes. Comparing the number of noncommunicating cases by using the conventional and 3D-CISS images, we found 26 new cases (19.4%) of 134 cases that were previously misdiagnosed as communicating hydrocephalus by conventional images. 3D-CISS sequence identified obstructive membranes invisible in other sequences, which facilitated selection of neuroendoscopy in the treatment of 31 patients (23.1%) in total who would have been otherwise treated with shunt insertion. These patients included 26 newly diagnosed noncommunicating cases after demonstration of intraventricular and/or fourth ventricular outlet membranes and 5 cases of communicating hydrocephalus with obstructing cisternal membranes. There were obstructions of the foramina of Luschka in 22 of 26 newly found noncommunicating cases. Conventional sequences are insensitive to obstructive membranes in CSF pathways, especially in the fourth ventricular exit foramina and the basal cisterns. 3D-CISS sequence, revealing these obstructive membranes, can alter patient treatment and prognosis.

Cisternal segments of the glossopharyngeal, vagus, and accessory nerves: detailed magnetic resonance imaging–demonstrated anatomy and neurovascular relationships

The aim of this study was to determine whether high-resolution MR imaging is suitable for identifying and differentiating among the nerve root bundles of the glossopharyngeal (cranial nerve [CN] IX), vagus (CN X), and accessory nerves (CN XI) as well as any adjacent vessels. Twenty-five patients (50 sides) underwent MR imaging using the 3D constructive interference in steady-state (CISS) sequence, as well as noncontrast and contrast-enhanced 3D time-of-flight (TOF) MR angiography. Two individuals scored these studies by consensus to determine how well these sequences displayed the neurovascular contacts and nerve root bundles of CNs IX and X and the cranial and spinal roots of CN XI. Landmarks useful for identifying each lower CN were specifically sought. The 3D CISS sequence successfully depicted CNs IX and X in 100% of the sides. Nerve root bundles of the cranial segment of CN XI were identified in 88% of the sides and those of the spinal segment of CN XI were noted in 93% of the sides. Landmarks useful in identifying the lower CNs included the vagal trigone, the choroid plexus of the lateral recess, the glossopharyngeal and vagal meatus, the inferior petrosal sinus, and the vertebral artery. The combined use of 3D CISS and 3D TOF sequences demonstrated neurovascular contacts at the nerve root entry or exit zones in 19% of all nerves visualized. The combined use of 3D CISS MR imaging and 3D TOF MR angiography (with or without contrast) successfully displays the detailed anatomy of the lower CNs and adjacent structures in vivo. These imaging sequences have the potential to aid the preoperative diagnosis of and the presurgical planning for pathology in this anatomical area.

Three-dimensional constructive interference in steady-state magnetic resonance imaging in syringomyelia: advantages over conventional imaging

Neuroradiology has become indispensable in detecting the pathophysiology in syringomyelia. Constructive interference in steady-state (CISS) magnetic resonance (MR) imaging can provide superior contrast at the sub-arachnoid tissue borders. As this region is critical in preoperative evaluation, the authors hypothesized that CISS imaging would provide superior assessment of syrinx pathology and surgical planning. Based on records collected from a database of 130 patients with syringomyelia treated at the authors' institution, 59 patients were prospectively evaluated with complete neuroradiological examinations. In addition to routine acquisitions with FLAIR, T1- and T2-weighted, and contrast-enhanced MR imaging series, the authors obtained sagittal cardiac-gated sequences to visualize cerebrospinal fluid (CSF) pulsations and axial 3D CISS MR sequences to detect focal arachnoid webs. Statistical qualitative and quantitative evaluations of spinal cord/CSF contrast, spinal cord/CSF delineation, motion artifacts, and artifacts induced by pulsatile CSF flow were performed. The 3D CISS MR sequences demonstrated a contrast-to-noise ratio significantly better than any other routine imaging sequence (p < 0.001). Moreover, 3D CISS imaging can detect more subarachnoid webs and cavitations in the syrinx than T2-weighted MR imaging with less flow-void artifact. The limitation of 3D CISS imaging is a susceptibility to motion artifacts that can cause reduced spatial resolution. Lengthy acquisition times for axial segments can be reduced with multiplanar reconstruction of 3D CISS-generated sagittal images. Constructive interference in steady-state imaging is the MR sequence of choice in the preoperative evaluation of syringomyelia, allowing significantly higher detection rates of focal subarachnoid webs, whereas standard T2-weighted MR imaging shows turbulent CSF flow voids. Constructive interference in steady-state MR imaging enables the neurosurgeon to accurately identify cases requiring decompression for obstructed CSF. Motion artifacts can be eliminated with technical variations.

Colorectal Carcinoma: In Vitro Evaluation with High-Spatial-Resolution 3D Constructive Interference in Steady-State MR Imaging

To retrospectively assess the accuracy of high-spatial-resolution three-dimensional (3D) constructive interference in steady-state (CISS) magnetic resonance (MR) imaging in the evaluation of mural invasion of colorectal carcinoma by using prospectively obtained in vitro images, with histopathologic analysis as the reference standard. Institutional review board approval was obtained for the prospective and retrospective components of this study, with informed consent for the former and waiver of informed consent for the latter. Surgical specimens were obtained in 92 patients (61 men, 31 women; mean age, 65 years) and contained 96 colorectal carcinomas. Specimens were examined with a 1.5-T MR system and a 4-cm-diameter loop coil. High-spatial-resolution 3D CISS MR images were obtained with 80 x 80-mm field of view, 512 x 512 matrix, and 0.7-mm section thickness, which resulted in a 0.017-mm(3) voxel size. The 3D data sets were postprocessed with surface-rendering software to generate virtual MR endoscopic images. The 3D CISS MR images were compared with histopathologic findings, and virtual MR endoscopic images were compared with macroscopic findings at surgery. Statistical analysis was performed with Spearman rank correlation. In 92 (96%) colorectal carcinomas, the depth of mural invasion depicted by 3D CISS MR imaging correlated well with the histopathologic stage, although the stage assigned with 3D CISS MR imaging was higher than that assigned with histopathologic analysis in four (4%) carcinomas (r = 0.976, P < .001). Sensitivity, specificity, and accuracy were 100%, 94%-96%, and 98%-100%, respectively. In 91 (95%) carcinomas, virtual MR endoscopy clearly depicted the macroscopic type of carcinoma, including gross configuration and tumor ulceration (r = 0.916, P < .001). High-spatial-resolution 3D CISS MR imaging has high diagnostic accuracy in the in vitro evaluation of mural invasion and macroscopic features of colorectal carcinomas.

Usefulness of Constructive Interference in Steady State (CISS) Imaging for the Diagnosis and Treatment of a Large Extradural Spinal Arachnoid Cyst

We present a rare case of a symptomatic large extradural arachnoid cyst extending from the lower thoracic to sacral region in a 12-year-old boy, who presented with the signs and symptoms of spinal cord compression over 4 years. Since the pedicle of the cyst could not be delineated using conventional magnetic resonance imaging (MRI), cine-mode MRI, and computed tomography scan, partial resection of the cyst was initially performed, which significantly improved motor function. After the first operation, a single pedicle was clearly demonstrated by 3D constructive interference in steady state (CISS) MRI. Thus, additional surgery aimed at closing the dural defect was performed to prevent future enlargement of the cyst. The operative findings were consistent with those of 3D CISS imaging. Clinical and radiological features of this lesion are discussed, focusing on the usefulness of 3D CISS MRI for preoperative evaluation, and especially for delineating the pedicle in cases of large extradural spinal arachnoid cysts.

Vascular compression of rostral medulla oblongata: prospective MR imaging study in hypertensive and normotensive subjects.

To prospectively evaluate prevalence of neurovascular contacts (NVCs) at the rostral medulla oblongata in normotensive and hypertensive subjects. Forty-three patients with severe essential hypertension and 45 normotensive subjects were matched for age, sex, and body mass index. Magnetic resonance (MR) imaging included transverse and coronal T2-weighted turbo spin-echo (section thickness, 3.0 mm), transverse three-dimensional (3D) time-of-flight MR angiographic (section thickness, 0.8 mm), and 3D constructive interference in steady state (CISS) (section thickness, 1.0 mm) sequences. All MR images were reviewed by two radiologists who were blinded to the hypertensive status of subjects. Presence and degree of NVC at rostral medulla and left/right rostral ventrolateral medulla (RVLM) were evaluated together with conspicuity of anatomic structures on MR images. Differences in prevalence of NVC among normotensive and hypertensive subjects were tested for statistical significance (P <.05) by using nonparametric tests. Among hypertensive patients, 34 (79%) of 43 showed NVC of rostral medulla at any location, and 14 (33%) of 43 had NVC at the left RVLM. In controls (normotensive subjects), 35 (78%) of 45 showed NVC of rostral medulla, and 17 (38%) of 45 had NVC at left RVLM. Prevalence of NVC was not significantly different between both groups at any location of rostral medulla. Compared with T2-weighted turbo spin-echo and 3D time-of-flight MR imaging sequences, 3D CISS offered better contrast resolution of neural and vascular structures and superior delineation of outer vascular contours. Vascular compression of the rostral medulla oblongata is a frequent finding in both hypertensive and normotensive subjects. Results of this study do not support NVC at left RVLM as an etiologic factor in essential hypertension.

Liliequist membrane: three-dimensional constructive interference in steady state MR imaging.

To evaluate the Liliequist membrane in healthy volunteers by using three-dimensional (3D) Fourier transformation constructive interference in steady state (CISS) magnetic resonance (MR) imaging. In 31 volunteers, the authors performed 3D CISS MR imaging. They divided the membrane into three segments: the sellar, diencephalic, and mesencephalic segments. MR images were evaluated to identify the segments, superior and inferior attachments, lateral border, and thickness of the Liliequist membrane. Three-dimensional CISS MR imaging depicted the sellar, diencephalic, and mesencephalic segments of the Liliequist membrane in the sagittal plane in 25 (81%), 16 (52%), and five (16%) of the 31 subjects, respectively. Transverse MR imaging depicted these segments in 24 (77%), 10 (32%), and two (6%) subjects, respectively, and coronal MR imaging depicted them in 24 (77%), 12 (39%), and two (6%) subjects, respectively. Clear attachment of the membrane to the dorsum sellae was observed in 22 (88%) of 25 subjects in whom the sellar segment was identified. Clear attachment to the mamillary body was identified in eight (50%) of 16 subjects in whom the diencephalic segment was identified. The Liliequist membrane was attached to the oculomotor nerve on seven (14%) of 50 sides of the lateral border and to the arachnoid membrane around the oculomotor nerve on 28 (56%) sides. In the sagittal plane, the thickness of the membrane was less than one-half the thickness of the third ventricle floor in 22 (88%) of 25 subjects. The Liliequist membrane can be visualized by using 3D CISS MR sequences.

Detailed anatomy of the intracranial segment of the hypoglossal nerve: neurovascular relationships and landmarks on magnetic resonance imaging sequences.

The thin hypoglossal nerve can be very difficult to distinguish on magnetic resonance (MR) images. The authors used a combination of sequences to increase the reliability of MR imaging in its demonstration of the 12th cranial nerve as well as to assess the course of the nerve, display its relationships to adjacent vessels, and provide landmarks for evaluating the nerve in daily practice. The study group consisted of 34 volunteers (68 nerves) in whom a three-dimensional (3D) Fourier-transformation constructive interference in steady-state (CISS) sequence and a 3D T1-weighted contrast-enhanced magnetization-prepared rapid-acquisition gradient-echo (MPRAGE) sequence were applied. Two trained neuroradiologists collaboratively identified the hypoglossal trigone, preolivary sulcus, 12th cranial nerve, posterior inferior cerebellar artery, vertebral artery, 12th nerve root sleeve, and the hypoglossal canal on each side. The 3D CISS sequence successfully demonstrated the hypoglossal trigone (100% of images), 12th nerve root bundles (100% of images), and 12th nerve sleeves (88.2% of images). The canalicular segment was exhibited with the aid of plain 3D CISS sequences in 74% of images and by using contrast-enhanced 3D CISS sequences and contrast-enhanced MPRAGE sequences in 100% of images. The landmarks that proved useful to identify the cisternal segment of the 12th cranial nerve included the hypoglossal trigone, preolivary sulcus, and 12th nerve root sleeve. Neurovascular contact was identified in 61% of root bundles. The roots were distorted in 44% of these contacts. The contrast-enhanced 3D CISS sequence consistently displayed the cisternal segment as well as the canalicular segments of the hypoglossal nerve and is, therefore, the best sequence to visualize the complete cranial course of this nerve. Landmarks such as the 12th nerve sleeves can assist in the identification of this nerve.