Magnetic resonance imaging of the cervical spine: comparison of 2D T2-weighted turbo spin echo, 2D T2*weighted gradient-recalled echo and 3D T2-weighted variable flip-angle turbo spin echo sequences

Cerebrospinal fluid flow artifact reduction with deep learning to optimize the evaluation of spinal canal stenosis on spine MRI

PURPOSE

The aim of study was to employ the Cycle Generative Adversarial Network (CycleGAN) deep learning model to diminish the cerebrospinal fluid (CSF) flow artifacts in cervical spine MRI. We also evaluate the agreement in quantifying spinal canal stenosis.

METHODS

For training model, we collected 9633 axial MR image pairs from 399 subjects. Then, additional 104 image pairs from 19 subjects were gathered for the test set. The deep learning model was developed using CycleGAN to reduce CSF flow artifacts, where T2 TSE images served as input, and T2 FFE images, known for fewer CSF flow artifacts. Post training, CycleGAN-generated images were subjected to both quantitative and qualitative evaluations for CSF artifacts. For assessing the agreement of spinal canal stenosis, four raters utilized an additional 104 pairs of original and CycleGAN-generated images, with inter-rater agreement evaluated using a weighted kappa value.

RESULTS

CSF flow artifacts were reduced in the CycleGAN-generated images compared to the T2 TSE and FFE images in both quantitative and qualitative analysis. All raters concordantly displayed satisfactory estimation results when assessing spinal canal stenosis using the CycleGAN-generated images with T2 TSE images (kappa = 0.61-0.75) compared to the original FFE with T2 TSE images (kappa = 0.48-0.71).

CONCLUSIONS

CycleGAN demonstrated the capability to produce images with diminished CSF flow artifacts. When paired with T2 TSE images, the CycleGAN-generated images allowed for more consistent assessment of spinal canal stenosis and exhibited agreement levels that were comparable to the combination of T2 TSE and FFE images.

Evaluating the Efficacy of Volume Isotropic Turbo Spin Echo Acquisition Versus T2-Weighted Turbo Spin Echo Imaging in the Diagnosis of Nerve Root and Perineuronal Pathologies in Spinal Disorders

Background While two-dimensional (2D) turbo spin echo (TSE) sequences offer better through-plane resolution than three-dimensional (3D) isotropic TSE sequences images, with a narrower thickness of the slice, 3D isotropic TSE sequences are known to have a weaker in-plane resolution as well as blurring of the image. These elements may make it more difficult to distinguish between nearby structures that may affect nerve roots and small nerve roots during spinal imaging. This study aimed to analyze the accuracy of T2 TSE sequence and volumetric isotropic TSE acquisition in determining the indentation of nerve roots and perineural diseases such as nerve sheath tumors and Tarlov cysts. Methods Fifty patients who attended the Department of Radiodiagnosis for magnetic resonance (MR) spine participated in this prospective study. Routine MR lumbosacral (LS) spine sequences, such as survey, coronal T2 short-tau inversion recovery (STIR), sagittal T2 TSE, sagittal T1 TSE, and axial T2 TSE, were carried out after a localizer was acquired. More sequences from volume isotropic turbo spin echo acquisition (VISTA) were acquired. For both 2D and 3D sequences, the visibility ratings for perineural cysts, spinal canal stenosis, and nerve root indentation were evaluated. Visibility ratings ranged from zero to four. Results In the cases of perineural cyst, spinal canal stenosis, and nerve root impingement, the mean difference between the VISTA and T2 TSE visibility scores was 0.04, 0.54, and 0.56, respectively. The VISTA and T2 TS had standard deviation differences of 0.006, 0.026, and 0.06, respectively. The "t" values for nerve root impingement, spinal canal stenosis, and perineural cysts were, in order, 50, 180, and 70. Because the p-value was <0.01, a statistically significant variation has been observed. Conclusion In the diagnosis of neural and perineuronal disorders, the visibility scores for 3D T2 TSE (VISTA) were considerably better than those for 2D T2 TSE in identifying perineural cysts, spinal canal stenosis, and nerve root indentation.

Diagnostic utility of 3D MRI sequences in the assessment of central, recess and foraminal stenoses of the spine: a systematic review

OBJECTIVE

To perform a systematic literature review on the diagnostic utility of 3D MRI sequences in the assessment of central canal, recess and foraminal stenosis in the spine.

METHODS

The databases PubMed, MEDLINE (via OVID) and The Cochrane Central Register of Controlled Trials, were searched for studies that investigated the diagnostic use of 3D MRI to evaluate stenoses in various parts of the spine in humans. Three reviewers examined the literature and conducted systematic review according to PRISMA 2020 guidelines.

RESULTS

Thirty studies were retrieved from 2 595 publications for this systematic review. The overall diagnostic performance of 3D MRI outperformed the conventional 2D MRI with reported sensitivities ranging from 79 to 100% and specificities ranging from 86 to 100% regarding the evaluation of central, recess and foraminal stenoses. In general, high level of agreement (both intra- and interrater) regarding visibility and pathology on 3D sequences was reported. Studies show that well-optimized 3D sequences allow the use of higher spatial resolution, similar scan time and increased SNR and CNR when compared to corresponding 2D sequences. However, the benefit of 3D sequences is in the additional information provided by them and in the possibility to save total protocol scan times.

CONCLUSION

The literature on the spine 3D MRI assessment of stenoses is heterogeneous with varying MRI protocols and diagnostic results. However, the 3D sequences offer similar or superior detection of stenoses with high reliability. Especially, the advantage of 3D MRI seems to be the better evaluation of recess stenoses.

MRI evaluation of foraminal changes in the cervical spine with assistance of a novel compression device

Standard supine Magnetic Resonance Imaging (MRI) does not acquire images in a position where most patients with intermittent arm radiculopathy have symptoms. The aim of this study was to test the feasibility of a new compression device and to evaluate image quality and foraminal properties during a Spurling test under MRI acquisition. Ten asymptomatic individuals were included in the study (6 men and 4 women; age range 27 to 55 years). First, the subjects were positioned in the cervical compression device in a 3 T MRI scanner, and a volume T2 weighted (T2w) sequence was acquired in a relaxed supine position (3 min). Thereafter, the position and compressive forces on the patient's neck (provocation position) were changed by maneuvering the device from the control room, with the aim to simulate a Spurling test, causing a mild foraminal compression, followed by a repeated image acquisition (3 min). A radiologist measured the blinded investigations evaluating cervical lordosis (C3-C7), foraminal area on oblique sagittal images and foraminal cross-distance in the axial plane. A total of three levels (C4-C7) were measured on the right side on each individual. Measurements were compared between the compressed and relaxed state. Reliability tests for inter- and intraclass correlation were performed. The device was feasible to use and well tolerated by all investigated individuals. Images of adequate quality was obtained in all patients. A significant increase (mean 9.4, p = 0.013) in the cervical lordosis and a decreased foraminal cross-distance (mean 32%, p < 0.001) was found, during the simulated Spurling test. The area change on oblique sagittal images did not reach a statistically significant change. The reliability tests on the quantitative measures demonstrated excellent intraobserver reliability and moderate to good interobserver reliability. Applying an individualized provocation test on the cervical spine, which simulates a Spurling test, during MRI acquisition was feasible with the novel device and provided images of satisfactory quality. MRI images acquired with and without compression showed changes in cervical lordosis and foraminal cross distance indicating the possibility of detecting changes of the foraminal properties. As a next step, the method is to be tested on symptomatic patients.

Comparison between 2D TSE and 3D SPACE in the evaluation of craniocervical ligaments

PURPOSE

To evaluate the MRI findings of the craniocervical junction ligaments and compare the 2D TSE sequence and 3D SPACE sequence on cervical spine MRI.

METHODS

Eighty cervical spine MRIs were retrospectively analyzed, including 2D TSE and 3D SPACE sequences. The visibility and morphology of the transverse ligament (TL) and alar ligament (AL) were evaluated by two readers using a five-point grading scale for visibility (1 = not visible, 2 = barely visible, 3 = adequately visible, 4 = good visibility, 5 = excellent visibility) and a four-point grading scale for morphology (0 = homogeneous low SI with normal thickness, 1 = high SI with normal thickness, 2 = reduced thickness, 3 = full-thickness rupture or indistinguishable from surrounding structures). The grades of the two sequences were compared. Reader agreements were measured using the percentage of exact agreement.

RESULT

The visibility grade of TL was significantly higher in 3D, indicating better visualization. The morphology grade of TL was significantly lower in the 3D, indicating more normal-appearing ligament. The exact agreements of visibility and morphology grade of TL tended to be higher in 3D. On the other hand, there was no significant difference in visibility grade of AL between the two sequences. The morphological grade of AL was significantly higher in 3D. The agreement of the morphological grade of AL tended to be lower in 3D.

CONCLUSION

The utilization of 3D sequences significantly improves the visibility of TL and could potentially reduce false-positive diagnoses of ligament injury.

Diagnostic Accuracy of Magnetic Resonance Imaging With 3-Dimensional T2-SPACE Techniques for Preganglionic Injury of the Brachial Plexus

PURPOSE

An accurate diagnosis of the site and severity of a brachial plexus injury is imperative for selecting the appropriate management. Conventional magnetic resonance imaging (MRI) does not allow for the precise interpretation of preganglionic injuries (pre-GIs), especially intravertebral canal injuries. We developed 4 MRI sequences of conventional 1.5-tesla 3-dimensional T2-weighted turbo spin echo sampling perfection with the application of optimized contrasts using different flip angles evolution (T2-SPACE) images to clearly visualize each component of the brachial plexus. The purpose of this study was to introduce basic normal and pathologic findings of our current MRI approach, focusing on its diagnostic accuracy for pre-GIs.

METHODS

We initially examined 119 patients with brachial plexus injuries who underwent surgical exploration by MRI using 4 sequences of the 1.5-tesla 3-dimensional T2-SPACE technique. We obtained coronal, transverse, coronal oblique, and coronal cuts of T2 short time inversion recovery. The images of 595 roots were interpreted by multiple-image synchronizing techniques of the 4 views to precisely interpret the presence of spinal cord edema, numbers of anterior and posterior rootlets, sites of ganglions, meningeal cysts, and the "black line sign" (displaced ruptured dura or bundles of ruptured rootlets). We assessed the accuracy, sensitivity, and specificity of these abnormal findings with regard to diagnosing pre-GIs by comparing surgical exploration.

RESULTS

The absence or decreased numbers of anterior and posterior rootlets and displacement of ganglions were definitive evidence of pre-GIs and the other findings, like spinal cord edema, meningeal cysts, and black line signs, were predictive signs.

CONCLUSIONS

The synchronizing techniques of the four 1.5-tesla 3-dimensional T2-SPACE images provided high diagnostic accuracy of pre-GIs.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

Comparison between T2-weighted two-dimensional and three-dimensional fast spin-echo MRI sequences for characterizing thoracolumbar intervertebral disc disease in small-breed dogs

Magnetic resonance imaging (MRI) is a standard test for diagnosis and treatment planning in dogs with degenerative thoracolumbar intervertebral disc disease (IVDD). However, published studies evaluating three-dimensional fast-spin echo (3D-FSE) pulse sequences for dogs with IVDD are currently limited. Aims of this retrospective, observational study were to compare findings from T2-weighted two- and three-dimensional fast spin-echo sequences (2D- and 3D-FSE, respectively) for a group of small breed dogs with thoracolumbar IVDD. Inclusion criteria were dogs with IVDD that underwent 1.5-Tesla MRI using both 2D-FSE and 3D-FSE sequences. For each dog and sequence, five pathologic indices were recorded: epidural fat discontinuation, vertebral canal compromise, spinal cord signal change, disc degeneration, and nerve root compression. Two independent investigators also scored visibility of the facet joint, intervertebral foramen, nerve roots, spinal cord grey-white matter differentiation, intervertebral discs, and epidural fat. The Wilcoxon signed-rank test was used to evaluate the between-sequence differences in pathologic indices and visibility scores. Interobserver agreement was measured using Cohen's weighted kappa along with 95% confidence intervals. A total of 21 dogs were sampled. The 3D-FSE sequences had higher pathologic indices of vertebral canal compromise (P = 0.020) and spinal cord signal change (P = 0.046) than 2D-FSE sequences. Furthermore, 3D-FSE sequences had higher visibility scores for the facet joint, intervertebral foramen, and nerve root structures (P < 0.001). Findings from the current supported the use of 3D-FSE sequences over 2D-FSE sequences for the evaluation of IVDD and visualization of spinal structures in small breed dogs.

Magnetic resonance imaging in the evaluation of cervical foraminal stenosis: comparison of 3D T2 SPACE with sagittal oblique 2D T2 TSE

OBJECTIVE

The oblique orientation of the cervical neural foramina challenges the implementation of a short MRI protocol with concurrent excellent visualization of the spine. While sagittal oblique T2-weighted sequences permit good evaluation of the cervical neuroforamina, all segments may not be equally well depicted on a single sequence and conspicuity of foraminal stenosis may be limited. 3D T2-weighted sequences can be reformatted in arbitrary planes, including the sagittal oblique. We set out to compare 3D T2w SPACE sequences with sagittal oblique reformations and sagittal oblique 2D T2w TSE sequences for the evaluation of cervical foraminal visibility and stenosis.

MATERIALS AND METHODS

Sixty consecutive patients who underwent MRI of the cervical spine with sagittal oblique 2D T2w TSE and 3D T2w SPACE sequences were included. Image homogeneity of the sequences was evaluated. Imaging sets were assessed for structure visibility and foraminal stenosis by two independent readers. Results of the sequences were compared by Wilcoxon matched-pairs tests. Interreader agreement was evaluated by weighted κ.

RESULTS

Visibility of most structures was rated good to excellent on both sequences (mean visibility scores ≥ 4.5 of 5), though neuroforaminal contents were better seen on sagittal oblique T2w TSE (mean scores 4.1-4.6 vs. 3.1-4.1 on 3D T2w SPACE, p < 0.01). Stenosis grades were comparable between sequences (mean 1.1-2.6 of 4), with slightly higher values for 3D T2w SPACE at some levels (difference ≤ 0.3 points).

CONCLUSION

3D T2w SPACE is comparable with sagittal oblique 2D T2w TSE in the evaluation of cervical neural foramina.

3D MRI of the Spine

Three-dimensional (3D) magnetic resonance imaging of the spine is now clinically feasible due to technological advancements. Its advantages over two-dimensional imaging include higher in-plane spatial resolution and the ability for reformation in any plane that enables time savings in image acquisition and aids more accurate interpretation. Multispectral 3D techniques for imaging around metal are sometimes useful for evaluating anatomy adjacent to spinal fixation hardware. 3D gradient-recalled echo sequences, including ultrashort or zero time to echo sequences, can provide osseous detail similar to conventional computed tomography.

Intracranial Cerebrospinal Fluid Volume Evaluation in Healthy People and Hydrocephalus Patients using SPACE Sequence

Introduction

Cerebrospinal Fluid (CSF) is produced mainly by the choroid plexus but with a substantial influence by the ependymal lining of the ventricles in the brain. Hydrocephalus occurs as a result of discrepancy in the production as well as circulation of CSF as a result of congenital and acquired conditions. Nevertheless, studies on the differences between CSF dynamics according to age and gender are still insufficient. Thus, this study evaluated the volume of intracranial CSF in healthy people and hydrocephalus patients taking into account the differences between CSF dynamics according to age and gender using Sampling Perfection with Application optimised Contrast using different flip-angle Evolution (SPACE) sequence.

Methods

120 healthy volunteers and 60 patients with hydrocephalus were included in this study. SPACE sequence was used to evaluate intracranial CSF with a 3.0T magnetic resonance machine. The total volume of intracranial CSF and the amount of CSF in the ventricle were obtained using a software, and the volume ratio of CSF in the subarachnoid space, the ventricle and the subarachnoid space were calculated.

Results

The mean volume of intracranial CSF, ventricular CSF, and subarachnoid CSF of male volunteers were (206.9±47.7) cm3, (33.0±10.7) cm3, (173.9±37.9) cm3 respectively. The average volume of intracranial CSF, ventricular CSF, and subarachnoid CSF of female volunteers were (199.7±44.9) cm3, (30.8±9.4) cm3, and (168.9±37.0) cm3, respectively. Thus, no significant statistically (P>0.05) difference between males and females was found. (3) The mean values ​​of intracranial CSF, ventricle CSF and subarachnoid CSF, ventricle and subarachnoid CSF volume ratio in patients with hydrocephalus were significantly greater than health volunteers. Thus, the difference between the two groups was statistically significant (P<0.05).

Conclusion

SPACE sequence can quantitatively determine the content of CSF. The change of CSF volume has nothing to do with gender but with age. It is feasible to use SPACE sequence to evaluate the spatial distribution and volume of intracranial CSF.

Combined signal averaging and compressed sensing: impact on quality of contrast-enhanced fat-suppressed 3D turbo field-echo imaging for pharyngolaryngeal squamous cell carcinoma

PURPOSE

To determine whether combined signal averaging and compressed sensing (CS averaging) improves the image quality of contrast-enhanced fat-suppressed T1-weighted three-dimensional turbo field-echo (FS T1W 3D-TFE) for evaluation of pharyngolaryngeal squamous cell carcinoma (PLSCC).

METHODS

This retrospective study included 27 patients with PLSCC. In all patients, contrast-enhanced FS T1W 3D-TFE imaging with CS averaging (number of excitations, 7) and that without CS averaging (number of excitations, 1) were obtained during the same acquisition time. Overall image quality, mucosal enhancement, vessel clarity, motion artifact, lesion conspicuity, and lesion edge sharpness were qualitatively evaluated using a 5-point scale. Images with and without CS averaging were compared using the Wilcoxon signed-rank test. Signal-to-noise ratio (SNR) of the lesion and the muscle structure were compared between the two imaging methods using a paired t-test.

RESULTS

Compared with the images without CS averaging, those with CS averaging showed significantly better overall image quality (p = 0.002), mucosal enhancement (p = 0.009), vessel clarity (p = 0.003), muscle edge clarity (p = 0.002), lesion conspicuity (p = 0.002), and lesion edge sharpness (p = 0.001); and less motion artifact (p < 0.001). The SNRs of the lesion and of the muscle structure were significantly higher for images with CS averaging than those without CS averaging (p < 0.001).

CONCLUSION

CS averaging improves the image quality of contrast-enhanced FS T1W 3D-TFE MR images for evaluation of PLSCC without requiring additional acquisition time.

Evaluation of diagnostic value and T2-weighted three-dimensional isotropic turbo spin-echo (3D-SPACE) image quality in comparison with T2-weighted two-dimensional turbo spin-echo (2D-TSE) sequences in lumbar spine MR imaging

Purpose

to evaluate diagnostic value and image quality of T2-weighted Three-dimensional isotropic turbo spin-echo (SPACE) in comparison with T2-weighted two-dimensional turbo spin-echo (TSE) sequences for comprehensive evaluation of lumbar spine pathologies.

Materials and methods

Thirty-five participants with lumbar discopathy were examined on a 1.5-T MRI system with both 2D TSE and 3D SPACE sequences. Obtained images were analyzed with synedra view personal (V 17.0.0.2) software in terms of calculating image quality factors such as signal to noise ratio (SNR) and contrast to noise ratio (CNR) for selected regions of interest. In addition, images were referred to radiologists to report their pathologic indexes. The visibility of anatomical structures in the 3D and 2D sequences was qualitatively assessed by two radiologists independently. Cohen's kappa (k) and Wilcoxon signed rank test was used for the statistical analysis.

Results

In this study, the 3D SPACE T2-weighted sequence showed significant higher SNR and CNR as well as visibility in all of the regions of interest except vertebrae and intervertebral discs (p-value < 0.05). Inter-observer agreement for visibility of regions of interest was substantial and perfect (k > 0.6). Also, inter-observer and inter-method agreements for pathologic indexes were substantial and perfect for all of the pathologic indexes (k > 0.6). Inter-observer agreement for 3D SPACE sequence was higher (k = 0.793) in comparison with 2D-TSE sequence (k = 0.603). 3D SPACE sequence and its multi-planar reconstructions (MPR) scan time were less (192 s) than 2D TSE in the sagittal, axial and coronal planes (209 s).

Conclusion

3D SPACE sequence for lumbar spine MRI proved to have higher SNR, CNR, and visibility for all regions of lumbar spine except vertebrae and disc. Inter-observer and inter-method agreements for pathologic indexes between 3D SPACE and 2D TSE sequences were substantial and 3D SPACE had a higher inter-observer agreement and less scan time. Therefore, T2 weighted 3D SPACE sequence, and its MPR might be an excellent alternative for 2D TSE in sagittal, axial, and coronal planes, especially for patients with abnormal curvature of the lumbar spine.

Diagnostic Accuracy of Zero-Echo Time MRI for the Evaluation of Cervical Neural Foraminal Stenosis

STUDY DESIGN

A cohort study.

OBJECTIVE

The aim of this study was to evaluate the clinical utility of Zero-Echo-Time (ZTE) magnetic resonance imaging (MRI) for the assessment of cervical neural foraminal stenosis (CNFS) through the comparison of inter-modality [computed tomography (CT) and ZTE-MRI] CNFS grade severity agreements.

SUMMARY OF BACKGROUND DATA

Conventional MRI limited in its ability to provide direct visualization of cortical bone. The highly organized tissue structure of cortical bone results in very short T2 values that preclude acquisition of sufficient signal intensity and positive image contrast. ZTE imaging permits visualization of tissues with very short transverse relaxation times, and is capable of displaying images with CT-like contrast.

METHODS

Thirty-four subjects were recruited from a clinical cohort of patients undergoing standard of care MRI and CT imaging for evaluation of CNFS. Standard of care CT imaging studies were obtained on all subjects within 6 months of their ZTE-MRI acquisition (mean time interval: 25.3 ± 54.1 days; median: 0 days). ZTE-MRI and CT imaging studies were evaluated and severity of CNFS was graded on a scale from 0 to 5 (0 = none; 5 = severe). Weighted-kappa statistics were used to assess agreement between ZTE and CT grades of CNFS on both sides (right and left) of each motion segment. Ordinal logistic mixed-effects regression analyses evaluated the effects of inter-modality position differences (flexion-extension curvature) on inter-modality differences in CNFS grade.

RESULTS

Substantial agreement (κ = 0.72) was found between ZTE- and CT-based grades of CNFS. Significant inter-modality differences in cervical spine curvature were found for all motion segments, except C2-3 and C3-4 (P < 0.05). However, no significant relationship was found between inter-modality differences in curvature, and inter-modality differences in CNFS grade for any motion segment (P = 0.28).

CONCLUSION

Results of the current study suggest that ZTE-MRI is well-suited for the evaluation of CNFS and may have the potential to obviate the need for concurrent CT scans in some cases.

LEVEL OF EVIDENCE

2.

Clinical utility of optimized three-dimensional T1-, T2-, and T2*-weighted sequences in spinal magnetic resonance imaging

This article reviews the clinical utility of 3D magnetic resonance imaging (MRI) sequences optimized for the evaluation of various intraspinal lesions. First, intraspinal tumors with hypervascular components and arteriovenous malformations (AVM) are clearly shown on contrast-enhanced (CE)-3D T1-weighted gradient-echo (GE) sequences with high spatial resolution. Second, dynamic CE-3D time-resolved magnetic resonance angiography (MRA) shows delineated feeding arteries of intraspinal AVM or arteriovenous fistula (AVF), greatly aiding subsequent digital subtraction angiography (DSA). Third, 3D multiecho T2*-weighted GE sequences are used to visualize intraspinal structures and spinal cord lesions and are sensitive to the magnetic susceptibility of intraspinal hemorrhages. Three-dimensional balanced steady-state free precession (SSFP) and multishot 3D balanced non-SSFP sequences produce contiguous thin images with high signal-to-noise ratio (SNR) in short scanning times. Intraspinal cystic lesions and small nerve-root tumors in subarachnoid space can be viewed using 3D balanced SSFP. Spinal cord myelomalacia and cord compression can be evaluated on fat-suppressed multishot 3D balanced non-SSFP. Finally, a 3D T2-weighted fast spin-echo (FSE) sequence with variable flip angle (FA) refocusing pulse improves through-plane spatial resolution over conventional 2D T2-weighted FSE sequences while matching image contrast.

Diagnostic Quality of 3D T2-SPACE Compared with T2-FSE in the Evaluation of Cervical Spine MRI Anatomy

BACKGROUND AND PURPOSE

Spinal anatomy has been variably investigated using 3D MRI. We aimed to compare the diagnostic quality of T2 sampling perfection with application-optimized contrasts by using flip angle evolution (SPACE) with T2-FSE sequences for visualization of cervical spine anatomy. We predicted that T2-SPACE will be equivalent or superior to T2-FSE for visibility of anatomic structures.

MATERIALS AND METHODS

Adult patients undergoing cervical spine MR imaging with both T2-SPACE and T2-FSE sequences for radiculopathy or myelopathy between September 2014 and February 2015 were included. Two blinded subspecialty-trained radiologists independently assessed the visibility of 12 anatomic structures by using a 5-point scale and assessed CSF pulsation artifact by using a 4-point scale. Sagittal images and 6 axial levels from C2-T1 on T2-FSE were reviewed; 2 weeks later and after randomization, T2-SPACE was evaluated. Diagnostic quality for each structure and CSF pulsation artifact visibility on both sequences were compared by using a paired t test. Interobserver agreement was calculated (κ).

RESULTS

Forty-five patients were included (mean age, 57 years; 40% male). The average visibility scores for intervertebral disc signal, neural foramina, ligamentum flavum, ventral rootlets, and dorsal rootlets were higher for T2-SPACE compared with T2-FSE for both reviewers (P < .001). Average scores for remaining structures were either not statistically different or the superiority of one sequence was discordant between reviewers. T2-SPACE showed less degree of CSF flow artifact (P < .001). Interobserver variability ranged between -0.02-0.20 for T2-SPACE and -0.02-0.30 for T2-FSE (slight to fair agreement).

CONCLUSIONS

T2-SPACE may be equivalent or superior to T2-FSE for the evaluation of cervical spine anatomic structures, and T2-SPACE shows a lower degree of CSF pulsation artifact.

Diagnosis of Nerve Root Compromise of the Lumbar Spine: Evaluation of the Performance of Three-dimensional Isotropic T2-weighted Turbo Spin-Echo SPACE Sequence at 3T

Objective

To explore the performance of three-dimensional (3D) isotropic T2-weighted turbo spin-echo (TSE) sampling perfection with application optimized contrasts using different flip angle evolution (SPACE) sequence on a 3T system, for the evaluation of nerve root compromise by disc herniation or stenosis from central to extraforaminal location of the lumbar spine, when used alone or in combination with conventional two-dimensional (2D) TSE sequence.

Materials and Methods

Thirty-seven patients who had undergone 3T spine MRI including 2D and 3D sequences, and had subsequent spine surgery for nerve root compromise at a total of 39 nerve levels, were analyzed. A total of 78 nerve roots (48 symptomatic and 30 asymptomatic sites) were graded (0 to 3) using different MRI sets of 2D, 3D (axial plus sagittal), 3D (all planes), and combination of 2D and 3D sequences, with respect to the nerve root compromise caused by posterior disc herniations, lateral recess stenoses, neural foraminal stenoses, or extraforaminal disc herniations; grading was done independently by two readers. Diagnostic performance was compared between different imaging sets using the receiver operating characteristics (ROC) curve analysis.

Results

There were no statistically significant differences (p = 0.203 to > 0.999) in the ROC curve area between the imaging sets for both readers 1 and 2, except for combined 2D and 3D (0.843) vs. 2D (0.802) for reader 1 (p = 0.035), and combined 2D and 3D (0.820) vs. 3D including all planes (0.765) for reader 2 (p = 0.049).

Conclusion

The performance of 3D isotropic T2-weighted TSE sequence of the lumbar spine, whether axial plus sagittal images, or all planes of images, was not significantly different from that of 2D TSE sequences, for the evaluation of nerve root compromise of the lumbar spine. Combining 2D and 3D might possibly improve the diagnostic accuracy compared with either one.

Effectiveness of a Rapid Lumbar Spine MRI Protocol Using 3D T2-Weighted SPACE Imaging Versus a Standard Protocol for Evaluation of Degenerative Changes of the Lumbar Spine

OBJECTIVE

Reducing lumbar spine MRI scanning time while retaining diagnostic accuracy can benefit patients and reduce health care costs. This study compares the effectiveness of a rapid lumbar MRI protocol using 3D T2-weighted sampling perfection with application-optimized contrast with different flip-angle evolutions (SPACE) sequences with a standard MRI protocol for evaluation of lumbar spondylosis.

MATERIALS AND METHODS

Two hundred fifty consecutive unenhanced lumbar MRI examinations performed at 1.5 T were retrospectively reviewed. Full, rapid, and complete versions of each examination were interpreted for spondylotic changes at each lumbar level, including herniations and neural compromise. The full examination consisted of sagittal T1-weighted, T2-weighted turbo spin-echo (TSE), and STIR sequences; and axial T1- and T2-weighted TSE sequences (time, 18 minutes 40 seconds). The rapid examination consisted of sagittal T1- and T2-weighted SPACE sequences, with axial SPACE reformations (time, 8 minutes 46 seconds). The complete examination consisted of the full examination plus the T2-weighted SPACE sequence. Sensitivities and specificities of the full and rapid examinations were calculated using the complete study as the reference standard.

RESULTS

The rapid and full studies had sensitivities of 76.0% and 69.3%, with specificities of 97.2% and 97.9%, respectively, for all degenerative processes. Rapid and full sensitivities were 68.7% and 66.3% for disk herniation, 85.2% and 81.5% for canal compromise, 82.9% and 69.1% for lateral recess compromise, and 76.9% and 69.7% for foraminal compromise, respectively.

CONCLUSION

Isotropic SPACE T2-weighted imaging provides high-quality imaging of lumbar spondylosis, with multiplanar reformatting capability. Our SPACE-based rapid protocol had sensitivities and specificities for herniations and neural compromise comparable to those of the protocol without SPACE. This protocol fits within a 15-minute slot, potentially reducing costs and discomfort for a large subgroup of patients.

An Imaging-Based Approach to Spinal Cord Infection

Infections of the spinal cord, nerve roots, and surrounding meninges are uncommon, but highly significant given their potential for severe morbidity and even mortality. Prompt diagnosis can be lifesaving, as many spinal infections are treatable. Advances in imaging technology have now firmly established magnetic resonance imaging (MRI) as the gold standard for spinal cord imaging evaluation, enabling the depiction of infectious myelopathies with exquisite detail and contrast. In this article, we aim to provide an overview of MRI findings for spinal cord infections with special focus on imaging patterns of infection that are primarily confined to the spinal cord, spinal meninges, and spinal nerve roots. In this context, we describe and organize this review around 5 distinct patterns of transverse spinal abnormality that may be detected with MRI as follows: (1) extramedullary, (2) centromedullary, (3) eccentric, (4) frontal horn, and (5) irregular. We seek to classify the most common presentations for a wide variety of infectious agents within this image-based framework while realizing that significant overlap and variation exists, including some infections that remain occult with conventional imaging techniques.

Magnetic Resonance Imaging in Patients With Mechanical Low Back Pain Using a Novel Rapid-Acquisition Three-Dimensional SPACE Sequence at 1.5-T: A Pilot Study Comparing Lumbar Stenosis Assessment With Routine Two-Dimensional Magnetic Resonance Sequences

PURPOSE

To minimize the burden of overutilisation of lumbar spine magnetic resonance imaging (MRI) on a resource-constrained public healthcare system, it may be helpful to image some patients with mechanical low-back pain (LBP) using a simplified rapid MRI screening protocol at 1.5-T. A rapid-acquisition 3-dimensional (3D) SPACE (Sampling Perfection with Application-optimized Contrasts using different flip angle Evolution) sequence can demonstrate common etiologies of LBP. We compared lumbar spinal canal stenosis (LSCS) and neural foraminal stenosis (LNFS) assessment on 3D SPACE against conventional 2-dimensional (2D) MRI.

METHODS

We prospectively performed 3D SPACE and 2D spin-echo MRI sequences (axial or sagittal T1-weighted or T2-weighted) at 1.5-T in 20 patients. Two blinded readers assessed levels L3-4, L4-5 and L5-S1 using: 1) morphologic grading systems, 2) global impression on the presence or absence of clinically significant stenosis (n = 60 disc levels for LSCS, n = 120 foramina for LNFS). Reliability statistics were calculated.

RESULTS

Acquisition time was ∼5 minutes for SPACE and ∼20 minutes for 2D MRI sequences. Interobserver agreement of LSCS was substantial to near perfect on both sequences (morphologic grading: kappa [k] = 0.71 SPACE, k = 0.69 T2-weighted; global impression: k = 0.85 SPACE, k = 0.78 T2-weighted). LNFS assessment had superior interobserver reliability using SPACE than T1-weighted (k = 0.54 vs 0.37). Intersequence agreement of findings between SPACE and 2D MRI was substantial to near perfect by global impression (LSCS: k = 0.78 Reader 1, k = 0.85 Reader 2; LNFS: k = 0.63 Reader 1, k = 0.66 Reader 2).

CONCLUSIONS

3D SPACE was acquired in one-quarter the time as the conventional 2D MRI protocol, had excellent agreement with 2D MRI for stenosis assessment, and had interobserver reliability superior to 2D MRI. These results justify future work to explore the role of 3D SPACE in a rapid MRI screening protocol at 1.5-T for mechanical LBP.

Comparison with Magnetic Resonance Three-Dimensional Sequence for Lumbar Nerve Root with Intervertebral Foramen

Study Design

Prospective study based on magnetic resonance (MR) imaging of the lumbar spinal root of the intervertebral foramen.

Purpose

This study was to compare MR three-dimensional (3D) sequences for the evaluation of the lumbar spinal root of the intervertebral foramen.

Overview of Literature

The diagnosis of spinal disorders by MR imaging is commonly performed using two-dimensional T1- and T2-weighted images, whereas 3D MR images can be used for acquiring further detailed data using thin slices with multi-planar reconstruction.

Methods

On twenty healthy volunteers, we investigated the contrast-to-noise ratio (CNR) of the lumbar spinal root of the intervertebral foramen with a 3D balanced sequence. The sequences used were the fast imaging employing steady state acquisition and the coherent oscillatory state acquisition for the manipulation of image contrast (COSMIC). COSMIC can be used with or without fat suppression (FS). We compared these sequence to determine the optimized visualization sequence for the lumbar spinal root of the intervertebral foramen.

Results

For the CNR between the nerve root and the peripheral tissue, these were no significant differences between the sequences at the entry of foramen. There was a significant difference and the highest CNR was seen with COSMIC-FS for the intra- and extra-foramen.

Conclusions

In this study, the findings suggest that the COSMIC-FS sequences should be used for the internal or external foramen for spinal root disorders.

Parallel-transmit-accelerated 2D Selective RF Excitation MR of the Temporal Bone: Enhanced Resolution of Labyrinthine and IAC Structures

RATIONALE AND OBJECTIVES

The purpose of this study was to compare a standard T2 SPACE sequence (standard-SPACE) used in temporal bone imaging at 3 T with a new parallel-transmit-accelerated 2D-selective radio frequency excitation technique for SPACE which was either time-improved or resolution-improved.

MATERIALS AND METHODS

Thirty-two consecutive patients were examined in this IRB-approved study using a standard T2 SPACE sequence, and then a time-improved zoomed SPACE sequence (short z-SPACE) with identical resolution but accelerated image acquisition and a resolution-improved zoomed SPACE sequence (high-resolution z-SPACE) with identical acquisition time but higher resolution at a 3-T magnetic resonance imaging system. Signal-to-noise ratio (SNR) was measured within selected regions of interest. Image quality of anatomic temporal bone structures was determined by two independent readers using a four-point visual scale.

RESULTS

Significant image quality improvement (p < 0.05) was observed in short z-SPACE and high-resolution z-SPACE, especially in structures of the cochlea and also regarding the delineation of the cranial nerves within the internal auditory canal. SNR measurements showed a lower SNR in the short z-SPACE and high-resolution z-SPACE sequences compared with standard-SPACE.

CONCLUSION

At 3 T parallel transmission using the zoomed SPACE sequences improves the delineation of small anatomical structures within the temporal bone significantly. It is especially helpful in depicting cochlear and internal auditory canal anatomy and can therefore improve imaging in patients with temporal bone pathologies.

3D T2 MR Imaging-Based Measurements of the Posterior Cervical Thecal Sac in Flexion and Extension for Cervical Puncture

BACKGROUND AND PURPOSE

The current standard technique for cervical puncture involves prone positioning with neck extension. The purpose of this study was to compare measurements of the posterior cervical thecal sac during neck flexion and extension in supine and prone positions by using high-resolution MR imaging to help determine the optimal positioning for cervical puncture.

MATERIALS AND METHODS

High-resolution T2-weighted MR imaging was performed of the cervical spine in 10 adult volunteers 18 years of age and older. Exclusion criteria included the following: a history of cervical spine injury/surgery, neck pain, and degenerative spondylosis. Images of sagittal 3D sampling perfection with application-optimized contrasts by using different flip angle evolutions were obtained in the following neck positions: supine extension, supine flexion, prone extension, and prone flexion. The degree of neck flexion and extension and the distance from the posterior margin of the spinal cord to the posterior aspect of the C1-C2 thecal sac were measured in each position.

RESULTS

The mean anteroposterior size of the posterior C1-C2 thecal sac was as follows: 4.76 mm for supine extension, 3.63 mm for supine flexion, 5.00 mm for prone extension, and 4.00 mm for prone flexion. Neck extension yielded a larger CSF space than flexion, independent of supine/prone positioning. There was no correlation with neck angle and thecal sac size.

CONCLUSIONS

The posterior C1-C2 thecal sac is larger with neck extension than flexion, independent of prone or supine positioning. Given that this space is the target for cervical puncture, findings suggest that extension is the ideal position for performing the procedure, and the decision for prone-versus-supine positioning can be made on the basis of operator comfort and patient preference/ability.

Three-Dimensional Isotropic MRI of the Cervical Spine: A Diagnostic Comparison With Conventional MRI

STUDY DESIGN

Retrospective diagnostic trial.

OBJECTIVE

To determine the diagnostic performance of 3-dimensional turbo spin-echo (3D-TSE) isotropic magnetic resonance imaging (MRI) in the assessment of cervical spine pathology.

SUMMARY OF BACKGROUND DATA

MRI is the imaging modality of choice for many cervical spine pathologies. However, axial imaging may be suboptimal if the image plane is oriented differently than the plane of interest, due to lordosis, kyphosis, or deformity. 3D-TSE isotropic MRI is a promising novel technology that bypasses this limitation by enabling dynamic image reformation in any desired orientation.

METHODS

Forty-eight patients who underwent 3D-TSE and conventional 2-dimensional fast spin-echo (2D-FSE) T2-weighted cervical spine MRI at our institution were randomly selected. 3D-TSE and 2D-FSE sequences from each subject were independently evaluated by 2 orthopedic spine surgeons and 4 musculoskeletal radiologists. Images were assessed using specific pilot-tested criteria for stenosis, herniation, and degenerative changes. Intermethod, interrater, and intrarater agreements for 3D-TSE and 2D-FSE, and Fleiss κ coefficients were determined.

RESULTS

The overall intermethod agreement was 80.7%. The interrater agreement was 75.9% for 3D-TSE and 75.7% for 2D-FSE (P=0.47). The intrarater agreement was 82.2% for 3D-TSE and 81.5% for 2D-FSE (P=0.71). Fleiss κ coefficients were 0.42 for 3D-TSE and 0.43 for 2D-FSE (P=0.62), indicating moderate interrater reliability. The intermethod agreement and the 2D-FSE intrarater agreement were statistically similar (P=0.49).

CONCLUSIONS

There is a high degree of agreement between 3D-TSE and 2D-FSE MRI in assessing the cervical spine. The intermethod variability was statistically similar to the intrinsic intrarater variability of 2D-FSE MRI. This study demonstrates that 3D-TSE yields at least equivalent diagnostic information as conventional 2D-FSE in the cervical spine. In addition, reviewers noted subjective advantages of 3D-TSE image reprocessing, especially when evaluating greater pathology or deformity, with a simplified image acquisition process.

Diagnostic value of oblique magnetic resonance images for evaluating cervical foraminal stenosis

BACKGROUND CONTEXT

The benefits of oblique magnetic resonance imaging (MRI) reformations to assess cervical neural foramina have been reported previously in clinical and cadaveric studies. But there is a paucity of literature investigating intra- and interobserver variabilities for assessing cervical foraminal stenosis using oblique MRI views.

PURPOSE

To determine the value of oblique MRI views compared with axial and sagittal views for assessing foraminal stenosis of the cervical spine using intra- and interobserver variabilities.

STUDY DESIGN

A retrospective study.

PATIENT SAMPLE

Twenty-six patients were included.

OUTCOME MEASURES

Two independent reviewers blindly identified the presence of foraminal stenosis as definite or indeterminate on the sagittal, axial, and oblique views. The assessments using the different views were compared using an independent t test. Intra- and interobserver variabilities were assessed using Kappa analysis.

METHODS

We evaluated the cervical spine MRIs of patients with varying degrees of foraminal stenosis. The mean age of the patients was 60.8 years (range 50-86 years). Male to female ratio was 16:10. The oblique images were obtained by reformatting the scans perpendicular to the long axis of the right and left neural foramina, respectively.

RESULTS

The oblique or axial views had significantly greater confidence rates for determining the presence of foraminal stenosis than the sagittal views (92.3%, 88.1% vs. 58.0%, respectively, p=.000). The oblique view had significantly better intraobserver agreement than the sagittal and axial images. Both the axial and oblique views had significantly better interobserver agreement than the sagittal images.

CONCLUSIONS

Oblique MRI views of the cervical spine significantly reduce the degree of intra- and interobserver variabilities and increase observer confidence in the assessment of foraminal stenosis. Our results suggest that routine use of oblique cervical MRI views might be useful for evaluating cervical foraminal stenosis.

Fast inner-volume imaging of the lumbar spine with a spatially focused excitation using a 3D-TSE sequence

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate the feasibility and technical quality of a zoomed three-dimensional (3D) turbo spin-echo (TSE) sampling perfection with application optimized contrasts using different flip-angle evolutions (SPACE) sequence of the lumbar spine.

MATERIALS AND METHODS

In this prospective feasibility study, nine volunteers underwent a 3-T magnetic resonance examination of the lumbar spine including 1) a conventional 3D T2-weighted (T2w) SPACE sequence with generalized autocalibrating partially parallel acquisition technique acceleration factor 2 and 2) a zoomed 3D T2w SPACE sequence with a reduced field of view (reduction factor 2). Images were evaluated with regard to image sharpness, signal homogeneity, and the presence of artifacts by two experienced radiologists. For quantitative analysis, signal-to-noise ratio (SNR) values were calculated.

RESULTS

Image sharpness of anatomic structures was statistically significantly greater with zoomed SPACE (P < .0001), whereas the signal homogeneity was statistically significantly greater with conventional SPACE (cSPACE; P = .0003). There were no statistically significant differences in extent of artifacts. Acquisition times were 8:20 minutes for cSPACE and 6:30 minutes for zoomed SPACE. Readers 1 and 2 selected zSPACE as the preferred sequence in five of nine cases. In two of nine cases, both sequences were rated as equally preferred by both the readers. SNR values were statistically significantly greater with cSPACE.

CONCLUSIONS

In comparison to a cSPACE sequences, zoomed SPACE imaging of the lumbar spine provides sharper images in conjunction with a 25% reduction in acquisition time.

Fast and accurate semi-automated segmentation method of spinal cord MR images at 3T applied to the construction of a cervical spinal cord template

Objective

To design a fast and accurate semi-automated segmentation method for spinal cord 3T MR images and to construct a template of the cervical spinal cord.

Materials and Methods

A semi-automated double threshold-based method (DTbM) was proposed enabling both cross-sectional and volumetric measures from 3D T₂-weighted turbo spin echo MR scans of the spinal cord at 3T. Eighty-two healthy subjects, 10 patients with amyotrophic lateral sclerosis, 10 with spinal muscular atrophy and 10 with spinal cord injuries were studied. DTbM was compared with active surface method (ASM), threshold-based method (TbM) and manual outlining (ground truth). Accuracy of segmentations was scored visually by a radiologist in cervical and thoracic cord regions. Accuracy was also quantified at the cervical and thoracic levels as well as at C2 vertebral level. To construct a cervical template from healthy subjects’ images (n=59), a standardization pipeline was designed leading to well-centered straight spinal cord images and accurate probability tissue map.

Results

Visual scoring showed better performance for DTbM than for ASM. Mean Dice similarity coefficient (DSC) was 95.71% for DTbM and 90.78% for ASM at the cervical level and 94.27% for DTbM and 89.93% for ASM at the thoracic level. Finally, at C2 vertebral level, mean DSC was 97.98% for DTbM compared with 98.02% for TbM and 96.76% for ASM. DTbM showed similar accuracy compared with TbM, but with the advantage of limited manual interaction.

Conclusion

A semi-automated segmentation method with limited manual intervention was introduced and validated on 3T images, enabling the construction of a cervical spinal cord template.

Comparison of contrast-enhanced isotropic 3D-GRE-T1WI sequence versus conventional non-isotropic sequence on preoperative staging of cervical cancer

Purpose

To compare contrast-enhanced isotropic 3D-GRE-T1WI sequence vs. conventional non-isotropic sequence in terms of image quality, estimated signal-to-noise ratio (eSNR), relative tumor contrast and performance of cervical cancer staging.

Methods

This retrospective study was approved by the institutional review board, and informed consent was waived. Seventy-one patients (47 ± 9.4 years), with pathologically-confirmed cervical cancer underwent axial contrast-enhanced 1mm³ isotropic 3D-GRE-T1WI sequence (herein referred to Isotropy), and 3-mm-thick non-isotropic sagittal and coronal sequences. Image quality score, eSNR and relative contrast between tumor to myometrium, gluteal muscle, and fat respectively, were compared between 3-mm-thick reconstructed images from Isotropy and directly scanned non-isotropic images by paired t-test. Difference in tumor staging obtained from Isotropy and combined Three-planes including reconstructed axial images, directly scanned sagittal and coronal sequence were compared by McNemar test.

Results

Both sequences showed similar image quality. Reconstructed images demonstrated higher eSNR, equal or lower relative tumor contrast compared with non-isotropic images. Compared with performing diagnosis on Three-planes, both reviewers showed higher accuracy when diagnosing vaginal invasion on Isotropy (p = 0.039 and 0.003, respectively).

Conclusion

Compared with non-isotropic sequence, 3.0T MR isotropic 3D-GRE-T1WI sequence exhibited better eSNR, providing more reliable clinical information for preoperative staging of cervical cancer.

MRI of the lumbar spine: comparison of 3D isotropic turbo spin-echo SPACE sequence versus conventional 2D sequences at 3.0 T

BACKGROUND

Three-dimensional (3D) fast spin-echo sequence with variable flip-angle refocusing pulse allows retrospective alignments of magnetic resonance imaging (MRI) in any desired plane.

PURPOSE

To compare isotropic 3D T2-weighted (T2W) turbo spin-echo sequence (TSE-SPACE) with standard two-dimensional (2D) T2W TSE imaging for evaluating lumbar spine pathology at 3.0 T MRI.

MATERIAL AND METHODS

Forty-two patients who had spine surgery for disk herniation and had 3.0 T spine MRI were included in this study. In addition to standard 2D T2W TSE imaging, sagittal 3D T2W TSE-SPACE was obtained to produce multiplanar (MPR) images. Each set of MR images from 3D T2W TSE and 2D TSE-SPACE were independently scored for the degree of lumbar neural foraminal stenosis, central spinal stenosis, and nerve compression by two reviewers. These scores were compared with operative findings and the sensitivities were evaluated by McNemar test. Inter-observer agreements and the correlation with symptoms laterality were assessed with kappa statistics.

RESULTS

The 3D T2W TSE and 2D TSE-SPACE had similar sensitivity in detecting foraminal stenosis (78.9% versus 78.9% in 32 foramen levels), spinal stenosis (100% versus 100% in 42 spinal levels), and nerve compression (92.9% versus 81.8% in 59 spinal nerves). The inter-observer agreements (κ = 0.849 vs. 0.451 for foraminal stenosis, κ = 0.809 vs. 0.503 for spinal stenosis, and κ = 0.681 vs. 0.429 for nerve compression) and symptoms correlation (κ = 0.449 vs. κ = 0.242) were better in 3D TSE-SPACE compared to 2D TSE. 3D TSE-SPACE with oblique coronal MPR images demonstrated better inter-observer agreements compared to 3D TSE-SPACE without oblique coronal MPR images (κ = 0.930 vs. κ = 0.681).

CONCLUSION

Isotropic 3D T2W TSE-SPACE at 3.0 T was comparable to 2D T2W TSE for detecting foraminal stenosis, central spinal stenosis, and nerve compression with better inter-observer agreements and symptom correlation.

Fast 3D T2 -weighted imaging using variable flip angle transition into driven equilibrium (3D T2 -TIDE) balanced SSFP for prostate imaging at 3T

PURPOSE

Three-dimensional (3D) T2 -weighted fast spin echo (FSE) imaging of the prostate currently requires long acquisition times. Our objective was to develop a fast 3D T2 -weighted sequence for prostate imaging at 3T using a variable flip angle transition into driven equilibrium (T2 -TIDE) scheme.

METHODS

3D T2 -TIDE uses interleaved spiral-out phase encode ordering to efficiently sample the ky -kz phase encodes and also uses the transient balanced steady-state free precession signal to acquire the center of k-space for T2 -weighted imaging. Bloch simulations and images from 10 healthy subjects were acquired to evaluate the performance of 3D T2 -TIDE compared to 3D FSE.

RESULTS

3D T2 -TIDE images were acquired in 2:54 minutes compared to 7:02 minutes for 3D FSE with identical imaging parameters. The signal-to-noise ratio (SNR) efficiency was significantly higher for 3D T2 -TIDE compared to 3D FSE in nearly all tissues, including periprostatic fat (45 ± 12 vs. 31 ± 7, P < 0.01), gluteal fat (48 ± 8 vs. 41 ± 10, P = 0.12), right peripheral zone (20 ± 4 vs. 16 ± 8, P = 0.12), left peripheral zone (17 ± 2 vs. 12 ± 3, P < 0.01), and anterior fibromuscular stroma (12 ± 4 vs. 4 ± 2, P < 0.01).

CONCLUSION

3D T2 -TIDE images of the prostate can be acquired quickly with SNR efficiency that exceeds that of 3D FSE.

Characteristics of spondylotic myelopathy on 3D driven-equilibrium fast spin echo and 2D fast spin echo magnetic resonance imaging: a retrospective cross-sectional study

In patients with spinal stenosis, magnetic resonance imaging of the cervical spine can be improved by using 3D driven-equilibrium fast spin echo sequences to provide a high-resolution assessment of osseous and ligamentous structures. However, it is not yet clear whether 3D driven-equilibrium fast spin echo sequences adequately evaluate the spinal cord itself. As a result, they are generally supplemented by additional 2D fast spin echo sequences, adding time to the examination and potential discomfort to the patient. Here we investigate the hypothesis that in patients with spinal stenosis and spondylotic myelopathy, 3D driven-equilibrium fast spin echo sequences can characterize cord lesions equally well as 2D fast spin echo sequences. We performed a retrospective analysis of 30 adult patients with spondylotic myelopathy who had been examined with both 3D driven-equilibrium fast spin echo sequences and 2D fast spin echo sequences at the same scanning session. The two sequences were inspected separately for each patient, and visible cord lesions were manually traced. We found no significant differences between 3D driven-equilibrium fast spin echo and 2D fast spin echo sequences in the mean number, mean area, or mean transverse dimensions of spondylotic cord lesions. Nevertheless, the mean contrast-to-noise ratio of cord lesions was decreased on 3D driven-equilibrium fast spin echo sequences compared to 2D fast spin echo sequences. These findings suggest that 3D driven-equilibrium fast spin echo sequences do not need supplemental 2D fast spin echo sequences for the diagnosis of spondylotic myelopathy, but they may be less well suited for quantitative signal measurements in the spinal cord.

Contrast enrichment of spinal cord MR imaging using a ratio of T1-weighted and T2-weighted signals

PURPOSE

We aimed to assess if the T1-weighted (T1w)/T2-weighted (T2w) signal ratio could be used to improve image contrast in MR spinal cord imaging.

MATERIALS AND METHODS

T1w and T2w cervical spinal cord MR images were acquired from 23 normal subjects using 3 Tesla (T) MR scanner. In addition, a multiple sclerosis patient, and a cervical spondylotic myelopathy patient were evaluated. White matter (WM) and gray matter (GM) signal intensities were measured for each image (T1w, T2w, and T1w/T2w) for seven cervical segments in each subject to calculate the contrast. Age-related changes in signal intensity were assessed at each location (lateral column, anterior column, dorsal column, and GM) for each image. Additionally, the imaging results of two subjects with spinal diseases and the controls were numerically compared.

RESULTS

The contrast between the WM and GM in the T1w/T2w ratio image was approximately twice as much as that in the T1w and T2w images (mean ± SD = 1.8 ± 0.4). The signal intensity ratio was related to age. For both clinical patients, the signal intensities were significantly lower in the lesion areas in the ratio images.

CONCLUSION

The T1w/T2w ratio images demonstrated increased image contrast compared with T1w and T2w images alone and, reduced inter-individual signal intensity differences.

Magnetic Resonance Imaging of Deep Infiltrating Endometriosis: Comparison of 2DT2- and 3DT2-Weighted TSE Sequences

Purpose

The purpose of this study was to compare image quality and diagnostic confidence of 3DT2 (SPACE) and 2DT2 magnetic resonance (MR) imaging for the evaluation of deep infiltrating endometriosis (DIE).

Methods

A total of 121 patients, referred for MR imaging because of suspected DIE with bowel involvement, underwent both 2DT2 and 3DT2 MR imaging. Two independent readers assessed both datasets for presence of DIE, artefacts and overall image quality. Inter-rater agreement scores were calculated using Cohen's kappa, and image quality and diagnostic confidence scores were compared using the Wilcoxon rank sum test.

Results

Inter-rater agreement scores for diagnosis of DIE (located retrocervical/vaginal cuff, or involving the bowel or bladder) using both 3DT2 SPACE and 2DT2, or solely 3DT2 and 2DT2 were excellent. Diagnostic confidence scores were similar for 3DT2 and 2DT2. Analysis of the 3DT2 dataset in combination with 2DT2 showed significant higher diagnostic confidence compared with solely 2DT2 for 1 location, which differed per reader. In 2DT2, artefacts were significantly lower, and overall image quality was significantly higher (p<0.01 and p<0.001, respectively).

Conclusions

Although 3DT2 SPACE could replace routine 2DT2-weighted imaging, the authors prefer 2DT2 over 3D, because of significantly fewer artefacts and a higher overall image quality with almost similar diagnostic confidence scores. Thus 3DT2 might be added to the standard protocol in indistinct cases.

T2 hyperintensity of medial lemniscus: higher threshold application to ROI measurements is more accurate in predicting small vessel disease

BACKGROUND

Medial lemniscus T2 hyperintensity (MLH) has been recently demonstrated as potential imaging marker for small vessel disease (SVD). Our purpose in this study is to improve accuracy of regions of interest (ROI) analysis for this imaging finding.

METHODS AND METHODS

Two neuroradiologists retrospectively reviewed 103 consecutive outpatient brain MRI. Medial lemniscus signal in dorsal pons was evaluated; visually on FLAIR and with ROI on T2. Original MRI interpretations were divided into three categories; SVD, multiple sclerosis (MS), and nonspecific WM changes (non).

RESULTS

Thirty-seven patients had SVD, 14 patients had MS, 52 had Non. Visual MLH was seen exclusively with SVD and was generally bilateral. Patients with visual MLH belonged to advanced SVD by imaging and clinical parameters. Compared to visual data, ROI analyses of MLH has been known to be compounded by false positives and negatives at low threshold (20% of adjacent to normal brainstem signal). With application of higher ROI threshold (25%), false positives were eliminated but false negatives increased. ROI analyses of MLH by experienced neuroradiologist were more reliable.

CONCLUSION

MLH seen on high threshold ROI analysis is a reliable radiologic marker in predicting SVD. ROI analysis of MLH should be performed by an experienced neuroradiologist.

Imaging of the entire cerebrospinal fluid volume with a multistation 3D SPACE MR sequence: feasibility study in patients with hydrocephalus

OBJECTIVES

To evaluate the feasibility of imaging the entire cerebrospinal fluid (CSF) volume using the SPACE MR sequence.

METHODS

The SPACE sequence encompassing the brain and spine was performed at 1.5 T in 12 healthy volunteers and 26 consecutive patients with hydrocephalus. Image contrast was estimated using difference ratios in signal intensity between CSF and its background. Segmentation of CSF was performed using geometrical features and a topological assumption of CSF shapes. Subarachnoid and ventricular CSF space volumes were assessed in volunteers and patients and linear discriminant analysis was performed.

RESULTS

Image contrast was 0.94 between the CSF and the brain and 0.90 between the CSF and the spinal cord. According to the phantom study, the accuracy of CSF volume measurement was 98.5 %. A clear distinction between patients and healthy volunteers was obtained using the linear discriminant analysis. Significant linear regression was found in healthy volunteers between ventricular (Vv) and the whole subarachnoid CSF volume (Vs) with Vv = 0.083 Vs.

CONCLUSIONS

Imaging of the entire CSF volume is feasible in healthy volunteers and patients with hydrocephalus. CSF volume can be obtained on a whole-body scale. This approach may be of use for the diagnosis and follow-up of patients with hydrocephalus.

KEY POINTS

• MRI assessment of CSF volume is feasible in healthy volunteers/hydrocephalus patients. • CSF volume can be obtained on a whole-body scale. • The ratio of subarachnoid and ventricular CSF is constant in healthy volunteers. • CSF linear discriminant analysis can distinguish between patients and healthy volunteers. • Entire CSF volume imaging is useful for diagnosing and following hydrocephalus.

Automated detection, 3D segmentation and analysis of high resolution spine MR images using statistical shape models

Recent advances in high resolution magnetic resonance (MR) imaging of the spine provide a basis for the automated assessment of intervertebral disc (IVD) and vertebral body (VB) anatomy. High resolution three-dimensional (3D) morphological information contained in these images may be useful for early detection and monitoring of common spine disorders, such as disc degeneration. This work proposes an automated approach to extract the 3D segmentations of lumbar and thoracic IVDs and VBs from MR images using statistical shape analysis and registration of grey level intensity profiles. The algorithm was validated on a dataset of volumetric scans of the thoracolumbar spine of asymptomatic volunteers obtained on a 3T scanner using the relatively new 3D T2-weighted SPACE pulse sequence. Manual segmentations and expert radiological findings of early signs of disc degeneration were used in the validation. There was good agreement between manual and automated segmentation of the IVD and VB volumes with the mean Dice scores of 0.89 ± 0.04 and 0.91 ± 0.02 and mean absolute surface distances of 0.55 ± 0.18 mm and 0.67 ± 0.17 mm respectively. The method compares favourably to existing 3D MR segmentation techniques for VBs. This is the first time IVDs have been automatically segmented from 3D volumetric scans and shape parameters obtained were used in preliminary analyses to accurately classify (100% sensitivity, 98.3% specificity) disc abnormalities associated with early degenerative changes.

Depicting the semicircular canals with inner-ear MRI: a comparison of the SPACE and TrueFISP sequences

PURPOSE

To assess the ability of magnetic resonance imaging (MRI) to depict the semicircular canals of the inner ear by comparing results from the sampling perfection with application-optimized contrasts by using different flip angle evolutions (SPACE) sequence with those from the true free induction with steady precession (TrueFISP) sequence.

MATERIALS AND METHODS

A 1.5-T MRI system was used to perform an in vivo study of 10 healthy volunteers and 17 patients. A three-point visual score was employed for assessing the depiction of the semicircular canals and facial and vestibulocochlear nerves and the contrast-to-noise ratio (CNR) was computed for the vestibule and pons on images with the SPACE and TrueFIPS sequences.

RESULTS

There were no susceptibility artifact-related filling defects with the SPACE sequence. However, the TrueFISP sequence showed filling defects for at least one semicircular canal on both sides in seven cases for healthy subjects and in 10 cases for patients. The CNR with the SPACE sequence was significantly higher than with the TrueFISP sequence (P < 0.05). There was no statistically significant difference in depicting the facial and the vestibulocochlear nerves (P = 0.32).

CONCLUSION

For the depiction of the semicircular canal, the SPACE sequence is superior to the TrueFISP sequence.

Uterine cervical carcinoma: a comparison of two- and three-dimensional T2-weighted turbo spin-echo MR imaging at 3.0 T for image quality and local-regional staging

OBJECTIVE

To compare three-dimensional (3D) T2-weighted turbo spin-echo (TSE) with multiplanar two-dimensional (2D) T2-weighted TSE for the evaluation of invasive cervical carcinoma.

METHODS

Seventy-five patients with cervical carcinoma underwent MRI of the pelvis at 3.0 T, using both 5-mm-thick multiplanar 2D (total acquisition time = 12 min 25 s) and 1-mm-thick coronal 3D T2-weighted TSE sequences (7 min 20 s). Quantitative analysis of signal-to-noise ratio (SNR) and qualitative analysis of image quality were performed. Local-regional staging was performed in 45 patients who underwent radical hysterectomy.

RESULTS

The estimated SNR of cervical carcinoma and the relative tumour contrast were significantly higher on 3D imaging (P < 0.0001). Tumour conspicuity was better with the 3D sequence, but the sharpness of tumour margin was better with the 2D sequence. No significant difference in overall image quality was noted between the two sequences (P = 0.38). There were no significant differences in terms of the diagnostic accuracy, sensitivity, and specificity of parametrial invasion, vaginal invasion, and lymph node metastases.

CONCLUSION

Multiplanar reconstruction 3D T2-weighted imaging is largely equivalent to 2D T2-weighted imaging for overall image quality and staging accuracy of cervical carcinoma with a shorter MR data acquisition, but has limitations with regard to the sharpness of the tumour margin.

Magnetic resonance imaging of noncommunicating hydrocephalus

INTRODUCTION

The purpose of this review is to describe the magnetic resonance imaging (MRI) findings in patients with noncommunicating hydrocephalus (NCH).

METHODS

We describe the technical aspects of MR sequences that are of use for the imaging of cerebrospinal fluid (CSF). Both the diagnosis of NCH and the follow-up after endoscopic third ventriculostomy (ETV) are discussed through clinical cases.

RESULTS

NCH is related to an obstacle hindering the CSF pathways. The combined use of anatomical and flow-sensitive MR sequences may help to characterize hydrocephalus. An imaging protocol is described at 1.5-T.

CONCLUSIONS

The first step of the diagnostic work-up consists of the detection of an obstacle hindering CSF flow pathways using both constructive interference in steady state and flow-sensitive MR sequences. CSF volumetry and quantification of ventricular wall movement may also improve the diagnosis and follow-up of patients with NCH.

Three-dimensional isotropic T2-weighted cervical MRI at 3T: comparison with two-dimensional T2-weighted sequences

AIM

To compare three-dimensional (3D) isotropic T2-weighted magnetic resonance imaging (MRI) sequences and reformation with two-dimensional (2D) T2-weighted sequences regarding image quality of the cervical spine at 3T.

MATERIALS AND METHODS

A phantom study was performed using a water-filled cylinder. The signal-to-noise and image homogeneity were evaluated. Fourteen (n=14) volunteers were examined at 3T using 3D isotropic T2-weighted sagittal and conventional 2D T2-weighted sagittal, axial, and oblique sagittal MRI. Multiplanar reformation (MPR) of the 3D T2-weighted sagittal dataset was performed simultaneously with image evaluation. In addition to artefact assessment, the visibility of anatomical structures in the 3D and 2D sequences was qualitatively assessed by two radiologists independently. Cohen's kappa and Wilcoxon signed rank test were used for the statistical analysis.

RESULT

The 3D isotropic T2-weighted sequence resulted in the highest signal-to-noise ratio (SNR) and lowest non-uniformity (NU) among the sequences in the phantom study. Quantitative evaluation revealed lower NU values of the cerebrospinal fluid (CSF) and muscles in 2D T2-weighted sagittal sequences compared to the 3D volume isotropic turbo spin-echo acquisition (VISTA) sequence. The other NU values revealed no statistically significant difference between the 2D turbo spin-echo (TSE) and 3D VISTA sequences (0.059<p<0.959). 3D VISTA images showed significantly fewer CSF flow artefacts (p<0.001) and better delineated intradural nerve rootlets (p=0.001) and neural foramina (p=0.016) compared to 2D sequences.

CONCLUSION

A 3D T2 weighted sequence is superior to conventional 2D sequences for the delineation of intradural nerve rootlets and neural foramina and is less affected by CSF flow artefacts.

Evaluation of lumber nerve root compression using thin-slice thickness coronal magnetic resonance imaging: three-dimensional fat-suppressed multi-shot balanced non-steady-state free precession versus three-dimensional T1-weighted spoiled gradient-recalled echo

PURPOSE

The aim of this study was to compare the three-dimensional fat-suppressed balanced non-steady-state free precession (3D FS-nSSFP) sequence and the 3D T1-weighted spoiled gradient-recalled echo (3D T1-GRE) sequence for evaluating lumbar nerve root compression with continuous thin-slice coronal magnetic resonance (MR) images.

MATERIALS AND METHODS

The institutional review board approved this study, and written informed consent was obtained from all 35 patients. We optimized continuous 2.5-mm thick lumbar coronal images with 3D FS-nSSFP and 3D T1-GRE. We calculated the contrast-to-noise ratio (CNR) for nerve roots and other structures on images with the two sequences. With knowledge of the final diagnosis, we assessed the visibility of nerve root compression on these images.

RESULTS

The CNR values of nerve roots were significantly higher on images with 3D FS-nSSFP than on those with 3D T1-GRE. These continuous thin-slice coronal images facilitated visualization of nerve root compression in >91% of patients. There was no statistically significant difference between the two sequences in the detection of nerve root compression.

CONCLUSION

Continuous thin-slice coronal MR images using 3D FS-nSSFP and 3D T1-GRE sequences are sufficient to evaluate lumbar nerve root compression, and 3D FS-nSSFP is superior to 3D T1-GRE for depiction of lumbar nerve roots.