MRI Predictors of Recurrence and Outcome after Acute Transverse Myelitis of Unidentified Etiology.

BACKGROUND AND PURPOSE: The early prediction of recurrence after an initial event of transverse myelitis helps to guide preventive treatment and optimize outcomes. Our aim was to identify MR imaging findings predictive of relapse and poor outcome in patients with acute transverse myelitis of unidentified etiology. MATERIALS AND METHODS: Spinal MRIs of 77 patients (mean age, 36.3 ± 20 years) diagnosed with acute transverse myelitis were evaluated retrospectively. Only the patients for whom an underlying cause of myelitis could not be identified within 3 months of symptom onset were included. Initial spinal MR images of patients were examined in terms of lesion extent, location and distribution, brain stem extension, cord expansion, T1 signal, contrast enhancement, and the presence of bright spotty lesions and the owl's eyes sign. The relapse rates and Kurtzke Expanded Disability Status Scale scores at least 1 year (range, 1-14 years) after a myelitis attack were also recorded. Associations of MR imaging findings with clinical variables were studied with univariate associations and binary log-linear regression. Differences were considered significant for P values < .05. RESULTS: Twenty-seven patients (35.1%) eventually developed recurrent disease. Binary logistic regression revealed 3 main significant predictors of recurrence: cord expansion (OR, 5.30; 95% CI, 1.33-21.11), contrast enhancement (OR, 5.05; 95% CI, 1.25-20.34), and bright spotty lesions (OR, 3.63; 95% CI, 1.06-12.43). None of the imaging variables showed significant correlation with the disability scores. CONCLUSIONS: Cord expansion, contrast enhancement, and the presence of bright spotty lesions could be used as early MR imaging predictors of relapse in patients with acute transverse myelitis of unidentified etiology. Collaborative studies with a larger number of patients are required to validate these findings.

Brain MRI Findings in Pediatric-Onset Neuromyelitis Optica Spectrum Disorder: Challenges in Differentiation from Acute Disseminated Encephalomyelitis.

BACKGROUND AND PURPOSE: Differentiating pediatric-onset neuromyelitis optica spectrum disorder from acute disseminated encephalomyelitis could be challenging, especially in cases presenting with only brain manifestations. Our purpose was to investigate brain MR imaging features that may help distinguish these 2 entities. MATERIALS AND METHODS: We retrospectively examined initial brain MR imaging studies of 10 patients with pediatric-onset neuromyelitis optica spectrum disorder (female/male ratio, 7:3) and 10 patients with acute disseminated encephalomyelitis (female/male ratio, 2:8). The mean age of the patients was 10.3 ± 5.6 and 8.7 ± 5.3 years, respectively. Brain lesions were evaluated with respect to location, extent, expansion, T1 hypointensity, contrast enhancement/pattern, and diffusion characteristics. The χ2 test (Yates or Fisher exact χ2tests) was used to compare differences between groups. RESULTS: Cerebral subcortical ± juxtacortical and pons ± middle cerebellar peduncle were the most frequent locations involved in both neuromyelitis optica spectrum disorder (n = 5 and 4, respectively) and acute disseminated encephalomyelitis (n = 9 and 7, respectively). Thalamic lesions were more frequent in acute disseminated encephalomyelitis (P = .020) and were detected only in 1 patient with neuromyelitis optica spectrum disorder. None of the patients with neuromyelitis optica spectrum disorder had hypothalamic, internal capsule, or cortical lesions. The internal capsule involvement was found to be significantly different between groups (P = .033). There was no significant difference in terms of extent, expansion, T1 hypointensity, contrast enhancement/pattern, and diffusion characteristics. CONCLUSIONS: Although there is a considerable overlap in brain MR imaging findings, thalamic and internal capsule involvement could be used to differentiate pediatric-onset neuromyelitis optica spectrum disorder from acute disseminated encephalomyelitis.

Longitudinal Persistence of Meningeal Enhancement on Postcontrast 7T 3D-FLAIR MRI in Multiple Sclerosis.

BACKGROUND AND PURPOSE: Preliminary research has demonstrated that postgadolinium 3D-FLAIR MR imaging at 7T may be a valuable tool for detecting abnormal meningeal enhancement and inflammation in MS; however, researchers have not systematically investigated its longitudinal persistence. We hypothesized that persistence of meningeal enhancement in MS varies on the basis of pattern of enhancement as well as demographic and clinical factors such as treatment status, disease phenotype, and disability score. MATERIALS AND METHODS: Thirty-one subjects with MS were prospectively scanned before and after intravenous contrast administration at 2 time points, approximately 1 year apart. Fifteen subjects in the cohort were scanned at another time approximately 1 year later. Foci of enhancement were categorized into 4 subtypes: subarachnoid spread/fill, subarachnoid nodular, vessel wall, and dural foci. We reviewed follow-up scans to determine whether foci changed between time points and then compared persistence with demographic and clinical variables. RESULTS: Persistence ranged from 71% to 100% at 1 year and 73% to 100% at 2 years, depending on the enhancement pattern. Subarachnoid spread/fill and subarachnoid nodular subtypes persisted less often than vessel wall and dural foci. Persistence was not significantly different between those on/off treatment and those with progressive/nonprogressive disease phenotypes. The number of persisting foci was significantly different in subjects with/without increasing Expanded Disability Status Scale scores (median, 12 versus 7.5, P = .04). CONCLUSIONS: Longitudinal persistence of meningeal enhancement on 3D-FLAIR at 7T in MS varies by pattern of enhancement and correlates with worsening disability; however, it is not significantly different in those on/off treatment or in those with progressive/nonprogressive disease phenotypes.

Radiation-Induced Myelitis: Initial and Follow-Up MRI and Clinical Features in Patients at a Single Tertiary Care Institution during 20 Years.

Myelitis is a rare complication of radiation exposure to the spinal cord and is often a diagnosis of exclusion. A retrospective review of clinical records and serial imaging was performed to identify subjects with documented myelitis and a history of prior radiation. Eleven patients fulfilled the inclusion criteria. All patients had longitudinally extensive cord involvement with homogeneous precontrast T1 hyperintense signal in the adjacent vertebrae, corresponding to the radiation field. T2 signal abnormalities involving the central two-thirds of the cord were seen in 6/11 patients (55%). The degree of cord expansion and contrast enhancement was variable but was seen in 6 (54%) and 5 (45%) patients, respectively. On follow-up, 2 patients developed cord atrophy, while complete resolution was noted in 1. Clinical improvement was noted in 5 patients, with symptom progression in 2 patients. Our results suggest that radiation myelitis is neither universally progressive nor permanent, and some radiographic and clinical improvement may occur.

Enhancing Brain Lesions during Acute Optic Neuritis and/or Longitudinally Extensive Transverse Myelitis May Portend a Higher Relapse Rate in Neuromyelitis Optica Spectrum Disorders.

BACKGROUND AND PURPOSE: Neuromyelitis optica spectrum disorders are inflammatory demyelinating disorders with optic neuritis and/or longitudinally extensive transverse myelitis episodes. We now know that neuromyelitis optica spectrum disorders are associated with antibodies to aquaporin-4, which are highly concentrated on astrocytic end-feet at the blood-brain barrier. Immune-mediated disruption of the blood-brain barrier may manifest as contrast enhancement on brain MR imaging. We aimed to delineate the extent and frequency of contrast enhancement on brain MR imaging within 1 month of optic neuritis and/or longitudinally extensive transverse myelitis attacks and to correlate contrast enhancement with outcome measures. MATERIALS AND METHODS: Brain MRIs of patients with neuromyelitis optica spectrum disorders were evaluated for patterns of contrast enhancement (periependymal, cloudlike, leptomeningeal, and so forth). The Fisher exact test was used to evaluate differences between the proportion of contrast enhancement in patients who were seropositive and seronegative for aquaporin-4 antibodies. The Mann-Whitney test was used to compare the annualized relapse rate and disease duration between patients with and without contrast enhancement and with and without seropositivity. RESULTS: Brain MRIs of 77 patients were evaluated; 59 patients (10 males, 49 females) were scanned within 1 month of optic neuritis and/or longitudinally extensive transverse myelitis attacks and were included in the analysis. Forty-eight patients were seropositive, 9 were seronegative, and 2 were not tested for aquaporin-4 antibodies. Having brain contrast enhancement of any type during an acute attack was significantly associated with higher annualized relapse rates (P = .03) and marginally associated with shorter disease duration (P = .05). Having periependymal contrast enhancement was significantly associated with higher annualized relapse rates (P = .03). CONCLUSIONS: Brain MRIs of patients with neuromyelitis optica spectrum disorders with contrast enhancement during an acute relapse of optic neuritis and/or longitudinally extensive transverse myelitis are associated with increased annual relapse rates.

Tract-Specific Diffusion Tensor Imaging in Cervical Spondylotic Myelopathy Before and After Decompressive Spinal Surgery: Preliminary Results.

PURPOSE: Diffusion tensor imaging (DTI) metrics of the cervical spinal cord in patients with cervical spondylotic myelopathy (CSM) were compared to those measured in healthy volunteers, using tract-specific region of interests (ROIs) across all cervical intervertebral disc levels. METHODS: Magnetic resonance (MR) imaging of the cervical spinal cord was performed in four patients with CSM and in five healthy volunteers on a 3-T MR scanner. Region-specific fractional anisotropy (FA) and mean diffusivity (MD) were calculated on axial imaging with ROI placement in the anterior, lateral, and posterior regions of the spinal cord. FA and MD were also calculated on sagittal acquisitions. Nonparametric statistical tests were used to compare controls and patients before and after surgery. RESULTS: FA values were significantly lower (p = 0.050) and MD values were significantly higher (p = 0.014) in CSM patients measured at level of maximal compression before surgery than in healthy controls in lateral and posterior ROIs, respectively. In posterior ROIs, MD values were significantly higher in patients before surgery compared to controls at all levels except C7-T1. CONCLUSION: Patients with CSM may demonstrate region-specific changes in DTI metrics when compared to healthy controls. Changes in DTI metrics may also occur at levels remote from site of compression.

Emergency Department MRI Scanning of Patients with Multiple Sclerosis: Worthwhile or Wasteful?

BACKGROUND AND PURPOSE: The increasing use of the emergency department MR imaging scanner at our institution raises questions about its added value to certain patient groups. We hypothesized that the use of emergency department MR imaging for identifying active demyelination in MS patients presenting with new neurologic symptoms would be of low yield. MATERIALS AND METHODS: Electronic medical records were reviewed for patients with MS who had emergency department MR imaging scans for a suspected MS exacerbation between March 1, 2014, and March 1, 2016. Details surrounding patient disposition, imaging, diagnosis, and management were determined. RESULTS: Of 115 patients in our study, 48 (41.7%) were ultimately diagnosed with an MS exacerbation. Nearly all patients with MS exacerbations (87.5%, 42/48) had active demyelination on their emergency department MR imaging, identified on 30.6% (33/108) of brain MRIs and 20.4% (19/93) of spinal MRIs. The presence of active demyelination at MRI was significantly associated with the ultimate diagnosis of an MS exacerbation (P < .001). MR imaging activity isolated to the spinal cord (ie, not found on concurrent brain MR imaging) was present in only 9 of 93 (9.7%) cases. Pseudoexacerbations accounted for 18 of the alternative diagnoses. CONCLUSIONS: Emergency department MR imaging is a worthwhile endeavor from a diagnostic standpoint for MS exacerbations despite not being part of the diagnostic criteria. This finding has corresponding downstream impact on management decisions to admit and/or administer intravenous steroids. However, we raise the question of whether clinicians over-rely on emergency department imaging for making exacerbation diagnoses. Additionally, spinal MR imaging is of questionable value as an addition to brain MR imaging due to a low yield of isolated spinal disease.

Evaluation and management of longitudinally extensive transverse myelitis: a guide for radiologists.

Longitudinal extensive transverse myelitis (LETM) is defined as an intramedullary spinal cord T2 signal abnormality extending craniocaudally over at least three vertebral bodies on an MRI study. Timely and appropriate diagnosis greatly facilitates patient management. The radiologist should review the relevant clinical information and determine the patient demographics and acuity of symptoms. Herein, we review the spectrum of diseases causing LETM and propose interpretation to guide the radiologist when presented with the MRI finding of LETM.

Asymmetry of the Odontoid Lateral Mass Interval in Pediatric Trauma CT: Do We Need to Investigate Further?

BACKGROUND AND PURPOSE: Odontoid lateral mass interval asymmetry can be within the normal spectrum or the result of traumatic atlantoaxial injury. We sought to set radiographic guidelines for further investigation of odontoid lateral mass interval asymmetry in cervical spine CT studies of pediatric trauma patients. MATERIALS AND METHODS: Fourteen children with C1-2 ligamentous injury or atlantoaxial rotational fixation/subluxation were retrospectively identified. We identified an additional 56 children fulfilling the following inclusion criteria: 1) They underwent C-spine CT to exclude traumatic injury, and 2) C-spine clearance and follow-up. Those were matched for age, sex, and severity of traumatic insult with the injured group. Clinical data were collected, and we measured the following parameters: anterior atlantodental interval; odontoid lateral mass interval; and the rotation of the head, C1, and C2. RESULTS: A significant difference (P < .001) was found between the groups in cervical tenderness and torticollis. There was a significant difference in the atlantodental interval value (3.3 ± 0.8 mm in injured and 2.2 ± 0.5 mm in noninjured). The directionality of head, C1, and C2 rotation was significantly (P < .05) more toward the same direction in the noninjured group. We found significant linear correlation between head rotation and ipsilateral odontoid lateral mass interval asymmetry only in the noninjured at C1-2. With multivariant analysis, the presence of cervical tenderness and an abnormal atlantodental interval were the most significant variables. CONCLUSIONS: Odontoid lateral mass interspace asymmetry in the absence of cervical tenderness and with a normal atlantodental interval is likely in the normal range and need not be further investigated.

White matter impairment in Rett syndrome: diffusion tensor imaging study with clinical correlations.

BACKGROUND AND PURPOSE: RTT, caused by mutations in the methyl CPG binding protein 2 (MeCP2) gene, is a disorder of neuronal maturation and connections. Our aim was to prospectively examine FA by DTI and correlate this with certain clinical features in patients with RTT. MATERIALS AND METHODS: Thirty-two patients with RTT underwent neurologic assessments and DTI. Thirty-seven age-matched healthy female control subjects were studied for comparison. With use of a 1.5T MR imaging unit, DTI data were acquired, and FA was evaluated to investigate multiple regional tract-specific abnormalities in patients with RTT. RESULTS: In RTT, significant reductions in FA were noted in the genu and splenium of the corpus callosum and external capsule, with regions of significant reductions in the cingulate, internal capsule, posterior thalamic radiation, and frontal white matter. In contrast, FA of visual pathways was similar to control subjects. FA in the superior longitudinal fasciculus, which is associated with speech, was equal to control subjects in patients with preserved speech (phrases and sentences) (P = .542), whereas FA was reduced in those patients who were nonverbal or speaking only single words (P < .001). No correlations between FA values for tracts and clinical features such as seizures, gross or fine motor skills, and head circumference were identified. CONCLUSIONS: DTI, a noninvasive technique to assess white matter tract pathologic features, may add specificity to the assessment of RTT clinical severity that is presently based on the classification of MeCP2 gene mutation and X-inactivation.

Distinct subtypes of myelitis in systemic lupus erythematosus.

OBJECTIVE: Myelitis causes pain, weakness, and sphincteric deficits, and is 1,000-fold more prevalent in patients with systemic lupus erythematosus (SLE) than in the general population. For the last century, descriptions of SLE myelitis have been primarily limited to case reports. In contrast, larger-scale cohort studies have revealed that myelitis occurring in the idiopathic demyelinating diseases (i.e., multiple sclerosis versus neuromyelitis optica) represents distinct syndromes. This study was undertaken to determine whether SLE myelitis similarly encapsulates distinct syndromes. METHODS: We analyzed a cohort of 22 patients with SLE and myelitis. Patients were assessed for neurologic variables related to myelitis and for clinical and serologic features of SLE. Magnetic resonance images of the spine, cerebrospinal fluid profiles, and autoantibody profiles were obtained. RESULTS: Eleven patients presented with signs of gray matter dysfunction (i.e., flaccidity and hyporeflexia), whereas 11 patients presented with signs of white matter dysfunction (i.e., spasticity and hyperreflexia). Patients with gray matter dysfunction were more likely to have irreversible paraplegia (P < 0.01), despite presenting with a monophasic versus polyphasic course (P = 0.01), higher levels of SLE activity (mean SLE Disease Activity Index 9.8 versus 2.0; P = 0.01), and a cerebrospinal fluid profile indistinguishable from bacterial meningitis. Prior to irreversible paraplegia, these patients presented with prodromes of fever and urinary retention, but were misdiagnosed by physicians of different specialties as having urinary tract infections. Patients with white matter dysfunction were more likely to meet criteria for neuromyelitis optica (P = 0.04) and were also more likely to have antiphospholipid antibodies (lupus anticoagulant) (P = 0.01). CONCLUSION: Our findings indicate that SLE myelitis encapsulates 2 distinct and previously unrecognized syndromes that can be distinguished clinically by gray matter versus white matter findings. Recognition of fever and urinary retention as prodromes of irreversible paraplegia may allow earlier diagnosis and treatment in SLE patients presenting with gray matter findings.

MR-trackable intramyocardial injection catheter.

There is growing interest in delivering cellular agents to infarcted myocardium to prevent postinfarction left ventricular remodeling. MRI can be effectively used to differentiate infarcted from healthy myocardium. MR-guided delivery of cellular agents/therapeutics is appealing because the therapeutics can be precisely targeted to the desired location within the infarct. In this study, a steerable intramyocardial injection catheter that can be actively tracked under MRI was developed and tested. The components of the catheter were arranged to form a loopless RF antenna receiver coil that enabled active tracking. Feasibility studies were performed in canine and porcine myocardial infarction models. Myocardial delayed-enhancement (MDE) imaging identified the infarcted myocardium, and real-time MRI was used to guide left ventricular catheterization from a carotid artery approach. The distal 35 cm of the catheter was seen under MRI with a bright signal at the distal tip of the catheter. The catheter was steered into position, the distal tip was apposed against the infarct, the needle was advanced, and a bolus of MR contrast agent and tissue marker dye was injected intramyocardially, as confirmed by imaging and postmortem histology. A pilot study involving intramyocardial delivery of magnetically labeled stem cells demonstrated the utility of the active injection catheter system.