SALW-Net: a lightweight convolutional neural network based on self-adjusting loss function for spine MR image segmentation.

Segmentation of intervertebral discs and vertebrae from spine magnetic resonance (MR) images is essential to aid diagnosis algorithms for lumbar disc herniation. Convolutional neural networks (CNN) are effective methods, but often require high computational costs. Designing a lightweight CNN is more suitable for medical sites lacking high-computing power devices, yet due to the unbalanced pixel distribution in spine MR images, the segmentation is often sub-optimal. To address this issue, a lightweight spine segmentation CNN based on a self-adjusting loss function, which is named SALW-Net, is proposed in this study. For SALW-Net, the self-adjusting loss function could dynamically adjust the loss weights of the two branches according to the differences in segmentation results and labels during the training; thus, the ability for learning unbalanced pixels is enhanced. Two separate datasets are used to evaluate the proposed SALW-Net. Specifically, the proposed SALW-Net has fewer parameter numbers than U-net (only 2%) but achieves higher evaluation scores than that of U-net (the average DSC score of SALW-Net is 0.8781, and that of U-net is 0.8482). In addition, the practicality validation for SALW-Net is also proceeding, including deploying the model on a lightweight device and producing an aid diagnosis algorithm based on segmentation results. This means our SALW-Net has clinical application potential for assisted diagnosis in low computational power scenarios.

A Lightweight Convolutional Neural Network Based on Dynamic Level-Set Loss Function for Spine MR Image Segmentation.

BACKGROUND: Spine MR image segmentation is important foundation for computer-aided diagnostic (CAD) algorithms of spine disorders. Convolutional neural networks segment effectively, but require high computational costs. PURPOSE: To design a lightweight model based on dynamic level-set loss function for high segmentation performance. STUDY TYPE: Retrospective. POPULATION: Four hundred forty-eight subjects (3163 images) from two separate datasets. Dataset-1: 276 subjects/994 images (53.26% female, mean age 49.02 ± 14.09), all for disc degeneration screening, 188 had disc degeneration, 67 had herniated disc. Dataset-2: public dataset with 172 subjects/2169 images, 142 patients with vertebral degeneration, 163 patients with disc degeneration. FIELD STRENGTH/SEQUENCE: T2 weighted turbo spin echo sequences at 3T. ASSESSMENT: Dynamic Level-set Net (DLS-Net) was compared with four mainstream (including U-net++) and four lightweight models, and manual label made by five radiologists (vertebrae, discs, spinal fluid) used as segmentation evaluation standard. Five-fold cross-validation are used for all experiments. Based on segmentation, a CAD algorithm of lumbar disc was designed for assessing DLS-Net's practicality, and the text annotation (normal, bulging, or herniated) from medical history data were used as evaluation standard. STATISTICAL TESTS: All segmentation models were evaluated with DSC, accuracy, precision, and AUC. The pixel numbers of segmented results were compared with manual label using paired t-tests, with P < 0.05 indicating significance. The CAD algorithm was evaluated with accuracy of lumbar disc diagnosis. RESULTS: With only 1.48% parameters of U-net++, DLS-Net achieved similar accuracy in both datasets (Dataset-1: DSC 0.88 vs. 0.89, AUC 0.94 vs. 0.94; Dataset-2: DSC 0.86 vs. 0.86, AUC 0.93 vs. 0.93). The segmentation results of DLS-Net showed no significant differences with manual labels in pixel numbers for discs (Dataset-1: 1603.30 vs. 1588.77, P = 0.22; Dataset-2: 863.61 vs. 886.4, P = 0.14) and vertebrae (Dataset-1: 3984.28 vs. 3961.94, P = 0.38; Dataset-2: 4806.91 vs. 4732.85, P = 0.21). Based on DLS-Net's segmentation results, the CAD algorithm achieved higher accuracy than using non-cropped MR images (87.47% vs. 61.82%). DATA CONCLUSION: The proposed DLS-Net has fewer parameters but achieves similar accuracy to U-net++, helps CAD algorithm achieve higher accuracy, which facilitates wider application. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 1.

LSW-Net: Lightweight Deep Neural Network Based on Small-World properties for Spine MR Image Segmentation.

BACKGROUND: Segmenting spinal tissues from MR images is important for automatic image analysis. Deep neural network-based segmentation methods are efficient, yet have high computational costs. PURPOSE: To design a lightweight model based on small-world properties (LSW-Net) to segment spinal MR images, suitable for low-computing-power embedded devices. STUDY TYPE: Retrospective. POPULATION: A total of 386 subjects (2948 images) from two independent sources. Dataset I: 214 subjects/779 images, all for disk degeneration screening, 147 had disk degeneration, 52 had herniated disc. Dataset II: 172 subjects/2169 images, 142 patients with vertebral degeneration, 163 patients with disc degeneration. 70% images in each dataset for training, 20% for validation, and 10% for testing. FIELD STRENGTH/SEQUENCE: T1- and T2-weighted turbo spin echo sequences at 3 T. ASSESSMENT: Segmentation performance of LSW-Net was compared with four mainstream (including U-net and U-net++) and five lightweight models using five radiologists' manual segmentations (vertebrae, disks, spinal fluid) as reference standard. LSW-Net was also deployed on NVIDIA Jetson nano to compare the pixels number in segmented vertebrae and disks. STATISTICAL TESTS: All models were evaluated with accuracy, precision, Dice similarity coefficient (DSC), and area under the receiver operating characteristic (AUC). Pixel numbers segmented by LSW-Net on the embedded device were compared with manual segmentation using paired t-tests, with P < 0.05 indicating significance. RESULTS: LSW-Net had 98.5% fewer parameters than U-net but achieved similar accuracy in both datasets (dataset I: DSC 0.84 vs. 0.87, AUC 0.92 vs. 0.94; dataset II: DSC 0.82 vs. 0.82, AUC 0.88 vs. 0.88). LSW-Net showed no significant differences in pixel numbers for vertebrae (dataset I: 5893.49 vs. 5752.61, P = 0.21; dataset II: 5073.42 vs. 5137.12, P = 0.56) and disks (dataset I: 1513.07 vs. 1535.69, P = 0.42; dataset II: 1049.74 vs. 1087.88, P = 0.24) segmentation on an embedded device compared to manual segmentation. DATA CONCLUSION: Proposed LSW-Net achieves high accuracy with fewer parameters than U-net and can be deployed on embedded device, facilitating wider application. EVIDENCE LEVEL: 2. TECHNICAL EFFICACY: 1.

State-of-the-art approach towards magnetic resonance imaging of the nervous system structures in patients with cardiac implantable electronic devices.

INTRODUCTION: MRI generated forces are the source of potential complications in patients with cardiac implantable electronic devices (CIED). The technological progress, and growing clinical evidence concerning the operation of the contemporary MR non-conditional CIEDs during MRI, have started to significantly change our every-day clinical practice. Nevertheless, a lot of patients who could have an MRI performed safely, still have been refused the examination. STATE-OF-THE-ART: In many clinical situations, an MRI examination in a patient with a CIED is reasonable, and is linked to a negligible risk of complications if performed under strict precautions. The MagnaSave Registry that evaluated the influence of nonthoracic MRI on the function of MR non-conditional CIEDs, and numerous studies involving thoracic and non-thoracic MRIs in patients with legacy CIEDs, have confirmed the feasibility and safety of such examinations. In this article, practical tips aimed towards improving the safety of MRI in MR conditional and non-conditional CIED patients are largely based on the very recently released (2017) HRS expert consensus statement. CLINICAL IMPLICATIONS: Clinical data emphasize the necessity of making the MRI more accessible to CIED patients, also in the case of MR non-conditional systems or when the thorax MR imaging is clinically reasonable. This goal should be achieved by increasing the number of centers complying with respective recommendations and applying protocols that would guarantee the highest safety level. FUTURE DIRECTIONS: Further studies are warranted to assess safety issues related to the main current contraindication to MRI, i.e., the presence of abandoned leads.

Reduction of motion, truncation and flow artifacts using BLADE sequences in cervical spine MR imaging.

PURPOSE: To assess the efficacy of the BLADE technique (MR imaging with 'rotating blade-like k-space covering') to significantly reduce motion, truncation, flow and other artifacts in cervical spine compared to the conventional technique. MATERIALS AND METHODS: In eighty consecutive subjects, who had been routinely scanned for cervical spine examination, the following pairs of sequences were compared: a) T2 TSE SAG vs. T2 TSE SAG BLADE and b) T2 TIRM SAG vs. T2 TIRM SAG BLADE. A quantitative analysis was performed using the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measures. A qualitative analysis was also performed by two radiologists, who graded seven image characteristics on a 5-point scale (0: non-visualization; 1: poor; 2: average; 3: good; 4: excellent). The observers also evaluated the presence of image artifacts (motion, truncation, flow, indentation). RESULTS: In quantitative analysis, the CNR values of the CSF/SC between TIRM SAG and TIRM SAG BLADE were found to present statistically significant differences (p < 0.001). Regarding motion and truncation artifacts, the T2 TSE BLADE SAG was superior compared to the T2 TSE SAG, and the T2 TIRM BLADE SAG was superior compared to the T2 TIRM SAG. Regarding flow artifacts, T2 TIRM BLADE SAG eliminated more artifacts than T2 TIRM SAG. CONCLUSIONS: In cervical spine MRI, BLADE sequences appear to significantly reduce motion, truncation and flow artifacts and improve image quality. BLADE sequences are proposed to be used for uncooperative subjects. Nevertheless, more research needs to be done by testing additional specific pathologies.

Desmoid type fibromatosis in the facet joint of lumbar spine: case report and review of literature.

Desmoid type fibromatosis is a benign fibroblastic tumor arising from the fascia or musculoaponeurosis. It may occur in various locations, but most commonly in the shoulder girdle and neck; to our knowledge, there has been no reported case originating from a facet joint of the spine. We report CT and MR imaging findings of a desmoid type fibromatosis, involving the facet joint of the L3-4 spine with bone involvement.

Desmoid Type Fibromatosis in the Facet Joint of Lumbar Spine: Case Report and Review of Literature

Desmoid type fibromatosis is a benign fibroblastic tumor arising from the fascia or musculoaponeurosis. It may occur in various locations, but most commonly in the shoulder girdle and neck; to our knowledge, there has been no reported case originating from a facet joint of the spine. We report CT and MR imaging findings of a desmoid type fibromatosis, involving the facet joint of the L3-4 spine with bone involvement.

The Use of Magnetic Resonance Imaging to Predict the Clinical Outcome of Non-Surgical Treatment for Lumbar Interverterbal Disc Herniation

OBJECTIVE: We wanted to investigate the relationship between the magnetic resonance (MR) findings and the clinical outcome after treatment with non-surgical transforaminal epidural steroid injections (ESI) for lumbar herniated intervertebral disc (HIVD) patients. MATERIALS AND METHODS: Transforaminal ESI were performed in 91 patients (50 males and 41 females, age range: 13-78 yrs) because of lumbosacral HIVD from March 2001 to August 2002. Sixty eight patients whose MRIs and clinical follow-ups were available were included in this study. The medical charts were retrospectively reviewed and the patients were divided into two groups; the successful (responders, n = 41) and unsatisfactory (non-responders, n = 27) outcome groups. A successful outcome required a patient satisfaction score greater than two and a pain reduction score greater than 50%. The MR findings were retrospectively analyzed and compared between the two groups with regard to the type (protrusion, extrusion or sequestration), hydration (the T2 signal intensity), location (central, right/left central, subarticular, foraminal or extraforaminal), and size (volume) of the HIVD, the grade of nerve root compression (grade 1 abutment, 2 displacement and 3 entrapment), and an association with spinal stenosis. RESULTS: There was no significant difference between the responders and non-responders in terms of the type, hydration and size of the HIVD, or an association with spinal stenosis (p > 0.05). However, the location of the HIVD and the grade of nerve root compression were different between the two groups (p < 0.05). CONCLUSION: MRI could play an important role in predicting the clinical outcome of non-surgical transforaminal ESI treatment for patients with lumbar HIVD.

Non-contiguous Multi-organ Involvement of an Inflammatory Myofibroblastic Tumor: A Case Report

An inflammatory myofibroblastic tumor (IMT) is relatively rare quasineoplastic lesion. An IMT usually presents as a single mass within a single organ or sometimes as multifocal lesions within a single anatomic region. An IMT involving noncontiguous multi-organs within different anatomic regions is extremely rare. We present a case of an aggressive IMT that involved the musculoskeletal system and multiple abdominal visceral organs.

Value of Preoperative Cervical Discography

PURPOSE: The aim of this study was to describe the method and the value of cervical discography as correlated with the MR findings. MATERIALS AND METHODS: Twenty-one discs in 11 consecutive patients who underwent cervical discography were analyzed. MR and CT discography (CTD) were performed in all patients. Discography was performed after swallowing barium for visualizing the pharynx and the esophagus to prevent penetration. We also analyzed the preceding causes of the subjects' cervical pain. The results of the pain provocation test were classified into concordant pain, discordant pain and a negative test. MRI was analyzed according to the T2-signal intensity (SI) of the disc, disc height, annular bulging and disc herniation. The CTD was analyzed for degeneration or radial tear of the disc, epidural leakage of the contrast agent and pooling of the contrast agent at the periphery of the disc. The pain provocation tests were correlated with the MR and CTD findings. We used the chi-square test to analyze the results. RESULTS: Concordant pain was observed in 14 cases, discordant pain in 3 cases and there were negative tests in 4 cases. There were no complications related to the procedure. Four patients had undergone anterior cervical fusion and four patients had pain that developed after traffic injuries. The decreased T2-SI and annular bulging on MRI, disc degeneration and peripheral pooling of the contrast agent on CT were significantly correlated with pain provocation. CONCLUSION: When the diagnosis of disc disease is difficult with performing MRI, cervical discography with using swallowed barium solution to reduce the penetration of the esophagus or hypopharynx may play be helpful. The decreased T2-SI and annular bulging on MRI correlated significantly with a positive result on the pain provocation test.

Metastatic Spinal Tumors: MR Findings after Novalis Radiosurgery

PURPOSE: To assess the therapeutic effect of Novalis radiosurgery for metastatic spinal tumors and evaluate the changes after treatment using MR imaging. MATERIALS AND METHODS: Between November 2003 and June 2005, 21 patients with metastatic spinal tumors underwent Novalis radiosurgery. Of these patients, the 7 with 13 metastatic spinal tumors who had undergone follow-up MR imaging were included in this study. The tumor locations were cervical spine in three, thoracic spine in four, lumbar spine in five and sacrum in one. During the first three months after Novalis radiosurgery, follow-up MRI was performed monthly and subsequently at 3-6-month intervals. On MR imaging, the volume of the tumors, the changes of their signal intensities and any changes in adjacent spinal cord were evaluated. RESULTS: Among the 13 lesions, 9 were decreased in volume (69.2%), 2 were stable (15.4%) and 2 were slightly increased. Seven of 9 lesions showed decreased signal intensity on T2 weighted images and 4 had compressive deformity. Two of 9 lesions had increased T2 signal intensity and tumor necrosis were detected on contrast-enhanced MR imaging. No changes in spinal cord were noted in any of the lesions. Those changes were detected on MRI obtained 1 month after Novalis surgery and the lesion sizes were gradually changed up to 3 months. CONCLUSION: Novalis radiosurgery was effective for the treatment of metastatic spinal tumor and the suppression of tumor growth. The estimation of therapeutic effect and detecting complication were precisely evaluated on MR imaging.

Radiological Evaluation of Percutaneous Endoscopic Lumbar Discectomy: A Three-Year Follow-Up Study

PURPOSE: We wanted to analyze the radiological changes of the patients who underwent percutaneous endoscopic lumbar discectomy (PELD) for treating soft disc herniation. MATERIALS AND METHODS: We retrospectively reviewed 30 patients (32 cases) who were observed for a minimum of 3 years after they underwent PELD. The authors investigated the postoperative radiological changes after PELD and the related clinical outcomes. All the patients received plain X-rays, CT and MRI both preoperatively and at the final follow-up. The radiological parameters were evaluated, including the disc height, the disc signal intensity, the subchondral marrow signal intensity, the sagittal plane instability and the facet joint osteoarthritis. RESULTS: The average amount of removed disc was 1.363 g and a significant correlation was detected between the narrowing of disc height and the amount of removed disc. Although the disc height and the disc height ratio were significantly decreased (-0.97 mm and 86.9%, respectively), the angle of sagittal rotation was well maintained. There were 18 (56.3%) cases of disc signal changes, six cases (18.8%) of subchondral marrow signal changes, and three cases (9.4%) of facet joint osteoarthritis. The success rate was 90.6%. CONCLUSION: Although disc height narrowing was observed, there was no postoperative instability and the overall clinical outcome was satisfactory. Our results show that PELD is a useful and minimal invasive procedure for the selected patients who are suffering with lumbar disc herniation.

A Case of Dialysis-related Amyloidosis of the Hip and Cervical Spine: Imaging Findings

Dialysis-related amyloidosis is a complication of long-term hemodialysis and it is characterized by the accumulation of beta2-microglobulin in the osteoarticular structures. We describe here the imaging findings of a case of dialysis-related amyloidosis involving the hip and cervical spine in a 62-year-old woman who received long-term dialysis. We focus here on the CT and MR imaging findings of the cervical spine and we include a review of the relevant literatures.

Correlations between the Cross-Sectional Area and Moment Arm Length of the Erector Spinae Muscle and the Thickness of the Psoas Major Muscle as Measured by MRI and the Body Mass Index in Lumbar Degenerative Kyphosis Patients

PURPOSE: Lumbar degenerative kyphosis (LDK) is a subgroup of the flatback syndrome, which is a condition caused by spinal degeneration. LDK is reported to be the most frequent cause of lumbar spine deformity in the farming districts of the 'Oriental' countries. We investigated the relationship between the cross-sectional area (CSA) and the moment arm length (MAL) of the erector spinae muscle and the thickness of the psoas major muscle (PT) and the body mass index (BMI) by performing statistical analysis, and we tried to show the crucial role of these variables for diagnosing LDK. MATERIALS AND METHODS: From July 2004 to April 2005, we retrospectively reviewed 17 LDK patients who had undergone anterior lumbar interbody fusion (ALIF) with posterior stabilization. We measured both the CSA & MAL on the transverse cross-sectional MR image of the trunk at the fourth to fifth vertebrae (L4/5). The MAL was defined as the anterior-posterior distance between the center of the erector spinae muscle and that of the vertebral body. A comparative study was undertaken between the LDK group and the matched (according to age & gender) control group with regard to the CSA, MAL, PT and BMI. RESULTS: The 17 LDK patients were all females [age: 62.5+/-4.93 years, height: 157+/-6.19 cm, weight: 55.59+/-4.7 kg, and BMI: 22.58+/-2.08 kg/m2]. The control group patients were all females [age: 63.6+/-2.27 years, height: 156+/-5.05 cm, weight: 59.65+/-7.39 kg and BMI: 24.38+/-2.94 kg/m2]. Spearman's rho indicated a positive association between the CSA & BMI (rho=0.49, p=0.046), between the MAL & BMI (rho=0.808, p=0.000) and between the CSA & PT (rho=0.566, p=0.018) in the LDK patients. In terms of the CSA versus MAL, there was a positive association in both groups (rho=0.67, p=0.000, MAL=0.023CSA+5.454 in the LDK group; rho=0.564, p=0.018, MAL=0.02CSA+5.832 in the control group with using linear regression analysis). Independent t-tests revealed that both groups had statistically different mean values (p=0.000) in terms of the CSA & MAL. CONCLUSION: This study showed that the patients with LDK not only had atrophied erector spinae muscles, but also atrophied psoas major muscles and short MALs, which is harmful because of the increased lower back load in the aged patients. Along with BMI, measurement of the CSA, MAL & PT on the MR images provides an objective assessment of the dimension & severity of the muscle atrophy in the LDK patients.

Lumbar Internal Disc Derangement in Patients with Chronic Low Back Pain: Diagnostic Value of the MR Imaging Findings as Compared with Provoked Discography as the Standard

PURPOSE: The aim of this study was to evaluate the diagnostic value of the MR Imaging findings with provoked discography used as the standard for painful lumbar disc derangement. MATERIALS AND METHODS: Two hundred patients (412 discs), (age range: 21-77 years), with chronic low back pain underwent MRI and provoked discography. We evaluated the MRI T2-WI findings such as disc degeneration, high-Intensity zones and endplate abnormalities. Subsequently, provocative discography was independently performed with using MR imaging, and a painful disc was defined when moderate to severe and concordant pain was provoked. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the MRI findings with using provoked discography as the standard. RESULTS: 400 discs showed abnormal findings such as disc degeneration, HIZ and endplate abnormalities on the T2-WI images. 12 discs showed normal findings. HIZ or endplate abnormalities were always combined with disc degeneration. The prevalence of each findings were disc degeneration (400 discs: 97.1%), HIZ (111 discs: 26.9%), type I endplate abnormalities (34 discs: 8.3%), type II endplate abnormalities (75 discs: 18.2%), the combined findings of HIZ and type I endplate abnormalities (2 discs: 0.5%) and the combined findings of HIZ and type II endplate abnormalities (7 discs: 1.7%). The disc degeneration showed high sensitivity (99.5%) and low specificity (5.0%), so only the NPV (91.7%) was significant, and not the PPV (47.8%). Each findings of HIZ (sensitivity, 36.5%; specificity, 81.4%; PPV, 63.18%; NPV, 59.5%), type I endplate abnormalities (11.0%, 94.1%, 61.8% and 54.8%, respectively), type II endplate abnormalities (19.8%, 83.2%, 50.7% and 54.3%, respectively), the combined findings of HIZ and type I endplate abnormalities (0.5%, 99.6%, 50.0% and 53.4%, respectively) and the combined findings of HIZ and type II endplate abnormalities (26.0%, 99.1%, 71.4% and 53.8%, respectively) show high specificity, but low sensitivity, so the PPV and NPV were also not significant. CONCLUSION: For diagnosing painful lumbar disc derangement, the MR imaging findings seem to be inadequate as predictive factors when provoked discography was used as the standard.

MR findings in Acute Disseminated Encephalomyelitis in Children

PURPOSE: We reviewed the distribution of lesion and the characteristics of the MR findings of acute disseminated encephalomyelitis (ADEM) in children. We evaluated the differences in the imaging findings and the clinical outcomes between the patients with deep gray matter involvement and the patients without deep gray matter involvement. MATERIALS AND METHODS: We retrospectively reviewed the 62 MR examinations of 21 patients who were discharged with the clinical diagnosis of ADEM. The patients were aged from 13 months to 12 years old (mean age: 4.5 years). Follow-up MR examinations were done one to 5 times (mean: 3 times) for 2 weeks to 4 years (mean: 3 months) after the initial examination. We compared the signal intensity on T2WI, the enhancement and residue on the MR images and the clinical outcomes between the patients with deep gray matter involvement and the patients without deep gray matter involvement. RESULTS: A total of 21 patients had white matter abnormalities on their initial MR. Fifteen patients (71%) had foci of increased signal intensity on T2WI in the deep gray matter: thalamus (n=15), globus pallidus (n=14) and putamen (n=10). On the follow-up images, all patients showed decreased signal intensity and enhancement of their lesion. We could not find the significant differences in signal intensity, enhancement and residue on the MRIs and also the clinical outcomes between the patients with deep gray matter involvement and the patients without deep gray matter involvement (<.05). CONCLUSION: There were no significant differences in the characteristics of the imaging and the clinical outcomes between the ADEM patients with deep gray matter involvement and those ADEM patients without deep gray matter involvement.

Posterior Epidural Migration of Lumbar Ruptured Disc: Report of Two Cases

Disc fragment migration occurs in 35%-72% of lumbar disc herniations. Most of the herniated disc fragments migrate in the rostal, caudal and lateral directions. Posterior epidural disc fragment migration is a rare finding and posterior migration causing Cauda Equina syndrome is exceptionally rare. We report here on two cases of L4-5 disc fragment posterior epidural migration that caused Cauda Equina syndrome, and this was diagnosed by performing radiological examination, and we also include a review of the related literature.

Intradural Cervical Disc Herniation: A Case Report

Intradural cervical disc herniation is an extremely rare condition and its pathogenesis is not certain. We experienced a case of intradural cervical disc herniation at the C4-5 level in a 56-year-old man. The preoperative sagittal T1- and T2- weighted images revealed an intradural iso-intensity lesion, with the spinal cord behind the posterior longitudinal ligament at the C4-5 disc level. The post-contrast T1-weighted image revealed a peripheral enhanced intradural lesion. We report here on a case of an intradural cervical disc herniation that was diagnosed by radiological examination, and we include a review of the related literature.

Evaluation of the Intraspinal Enhancement for Medulloblastoma on MR Imaging

PURPOSE: The purpose of this study was to analyze the enhancement pattern of the spinal cord for patients with medulloblastoma, and to correlate the enhancement pattern with cerebrospinal fluid (CSF) tumor seeding. MATERIALS AND METHODS: We retrospectively reviewed 84 MR images, including the initial and follow-up studies after chemotherapy or radiation therapy, of 25 patients with medulloblastoma who were aged from 2 to 13 years. We analyzed the spinal leptomeningeal enhancement pattern on the MR images. The leptomeningeal enhancement patterns were categorized into three types: Type I, fine or discontinuous linear enhancement, and type II, continuous linear or nodular enhancement, and type III, intradural mass formation. We correlated the enhancement pattern on MRI with the results of CSF cytology at the initial and follow - up examinations after treatment. RESULTS: Of total 25 patients, type I enhancement was observed for 14 patients. Twelve patients were negative on the initial CSF cytology and 2 patients were positive. On the follow-up MR studies, 14 patients showed no change or only a slight decrease of enhancement, and all were negative on the follow-up CSF cytology. Type II enhancement patterns were observed in seven patients, and all of them were positive on the initial CSF cytology. On follow-up MR study, one patient revealed an increased enhancement with the positive result on the follow-up CSF cytology, and six patients had decreased enhancement on the follow-up MR studies with negative conversion on the follow-up CSF cytology. Type III enhancement patterns were observed in four patients and all of them were positive on the initial CSF cytology. All four patients with intradural mass formations revealed progression of the lesions on follow-up MR studies, and all of them were positive on the follow-up CSF cytology. CONCLUSION: Type II and III enhancement patterns always represented CSF seeding and a type I enhancement pattern had a low probability of metastasis.

Non-Contiguous Spinal Injury in Cervical Spinal Trauma: Evaluation with Cervical Spine MRI

OBJECTIVE: We wished to evaluate the incidence of non-contiguous spinal injury in the cervicothoracic junction (CTJ) or the upper thoracic spines on cervical spinal MR images in the patients with cervical spinal injuries. MATER AND METHODS: Seventy-five cervical spine MR imagings for acute cervical spinal injury were retrospectively reviewed (58 men and 17 women, mean age: 35.3, range: 18-81 years). They were divided into three groups based on the mechanism of injury; axial compression, hyperflexion or hyperextension injury, according to the findings on the MR and CT images. On cervical spine MR images, we evaluated the presence of non-contiguous spinal injury in the CTJ or upper thoracic spine with regard to the presence of marrow contusion or fracture, ligament injury, traumatic disc herniation and spinal cord injury. RESULTS: Twenty-one cases (28%) showed CTJ or upper thoracic spinal injuries (C7-T5) on cervical spinal MR images that were separated from the cervical spinal injuries. Seven of 21 cases revealed overt fractures in the CTJs or upper thoracic spines. Ligament injury in these regions was found in three cases. Traumatic disc herniation and spinal cord injury in these regions were shown in one and two cases, respectively. The incidence of the non-contiguous spinal injuries in CTJ or upper thoracic spines was higher in the axial compression injury group (35.3%) than in the hyperflexion injury group (26.9%) or the hyperextension (25%) injury group. However, there was no statistical significance (p > 0.05). CONCLUSION: Cervical spinal MR revealed non-contiguous CTJ or upper thoracic spinal injuries in 28% of the patients with cervical spinal injury. The mechanism of cervical spinal injury did not significantly affect the incidence of the non-contiguous CTJ or upper thoracic spinal injury.