Magnetic Resonance Imaging of the Lumbar Spine: Recommendations for Acquisition and Image Evaluation from the BACPAC Spine Imaging Working Group.

Management of patients suffering from low back pain (LBP) is challenging and requires development of diagnostic techniques to identify specific patient subgroups and phenotypes in order to customize treatment and predict clinical outcome. The Back Pain Consortium (BACPAC) Research Program Spine Imaging Working Group has developed standard operating procedures (SOPs) for spinal imaging protocols to be used in all BACPAC studies. These SOPs include procedures to conduct spinal imaging assessments with guidelines for standardizing the collection, reading/grading (using structured reporting with semi-quantitative evaluation using ordinal rating scales), and storage of images. This article presents the approach to image acquisition and evaluation recommended by the BACPAC Spine Imaging Working Group. While the approach is specific to BACPAC studies, it is general enough to be applied at other centers performing magnetic resonance imaging (MRI) acquisitions in patients with LBP. The herein presented SOPs are meant to improve understanding of pain mechanisms and facilitate patient phenotyping by codifying MRI-based methods that provide standardized, non-invasive assessments of spinal pathologies. Finally, these recommended procedures may facilitate the integration of better harmonized MRI data of the lumbar spine across studies and sites within and outside of BACPAC studies.

Ultrahigh-b diffusion-weighted imaging for quantitative evaluation of myelination in shiverer mouse spinal cord.

PURPOSE: To perform a quantitative evaluation of myelination on WT and myelin-deficient (shiverer) mouse spinal cords using ultrahigh-b diffusion-weighted imaging (UHb-DWI). METHODS: UHb-DWI of ex vivo on spinal cord specimens of two shiverer (C3HeB/FeJ-shiverer, homozygous genotype for MbPshi ) and six WT (Black Six, C3HeB/FeJ) mice were acquired using 3D multishot diffusion-weighted stimulated-echo EPI, a homemade RF coil, and a small-bore 7T MRI system. Imaging was performed in transaxial plane with 75 × 75 µm2 in-plane resolution, 1-mm-slice thickness, and radial DWI using bmax = 42,890 s/mm2 . Histological evaluation was performed on upper thoracic sections using optical and transmission electron microscopy. Numerical Monte Carlo simulations (MCSs) of water diffusion were performed to facilitate interpretation of UHb-DWI signal-b curves. RESULTS: The white matter ultrahigh-b radial DWI (UHb-rDWI) signal-b curves of WT mouse cords behaved biexponentially with high-b diffusion coefficient DH < 0.020 × 10-3 mm2 /s. However, as expected with less myelination, the signal-b of shiverer mouse cords behaved monoexponentially with significantly greater DH = 0.162 × 10-3 , 0.142 × 10-3 , and 0.164 × 10-3 mm2 /s at anterodorsal, posterodorsal, and lateral columns, respectively. The axial DWI signals of all mouse cords behaved monoexponentially with D = (0.718-1.124) × 10-3 mm2 /s. MCS suggests that these elevated DH are mainly induced by increased water exchange at the myelin sheath. Microscopic results were consistent with the UHb-rDWI findings. CONCLUSION: UHb-DWI provides quantitative differences in myelination of spinal cords from myelin-deficit shiverer and WT mice. UHb-DWI may become a powerful tool to evaluate myelination in demyelinating disease models that may translate to human diseases, including multiple sclerosis.

Defining Disc Biopsy Timing in Relation to Blood Culture Results for Inpatients with Suspected Discitis-Osteomyelitis.

PURPOSE: To determine optimal timing of biopsy for suspected discitis-osteomyelitis (DOM) with respect to preliminary blood culture results and the effect of biopsy timing on hospital length of stay (LOS). MATERIALS AND METHODS: This retrospective study reviewed disc/vertebral biopsies for suspected DOM performed between 2010 and 2018. A total of 107 disc/vertebral biopsies were performed on 96 inpatients (mean ± SD age 57.9 ± 14.5 years, 68 men/28 women) for suspected DOM, and 100 cases of DOM were clinically confirmed and treated. Descriptive and regression statistics were performed with LOS as the primary outcome. RESULTS: Of disc biopsies in clinically confirmed cases, 68% were positive; 20% of all biopsies had preliminary positive blood cultures after 2 hospital days. There was no difference in LOS between cases with biopsy performed ≤ 2 days after blood culture and cases with biopsy performed > 2 days after blood culture (P = .40). Regression analysis showed no association between positive biopsy results and sepsis, white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), or C-reactive protein (CRP). Biopsy yield was not significantly decreased in patients previously taking antibiotics (P = .09). CONCLUSIONS: Waiting 2 days for preliminary blood culture results could avoid disc/vertebral biopsy in 20% of patients and does not significantly impact hospital LOS. Additionally, clinical factors (sepsis, WBC count, CRP, and ESR) do not have predictive value for positive disc biopsy results.

Ultra-high-b radial diffusion-weighted imaging (UHb-rDWI) of human cervical spinal cord.

BACKGROUND: Injury in the cervical spinal cord (CSC) can lead to varying degrees of neurologic deficit and persistent disability. Diffusion tensor imaging (DTI) is a promising method to evaluate white matter integrity and pathology. However, the conventional DTI results are limited with respect to the specific details of neuropathology and microstructural architecture. In this study we used ultrahigh-b radial-DWI (UHb-rDWI) with b-values ranging from 0 to ∼7500 s/mm2 and calculated decay constant (DH ) at the high b-values, which gives much deeper insight about the microscopic environment of CSC white matter. PURPOSE: To evaluate a novel diffusion MRI, UHb-rDWI technique for imaging of the CSC. STUDY TYPE: Longitudinal. SUBJECTS: Four healthy controls, each scanned twice. FIELD STRENGTH/SEQUENCE: 3T/2D single shot diffusion-weighted stimulated echo planar imaging with reduced field of view. ASSESSMENT: The signal from each pixel of b0 (b = 0) and b-value (b ≠ 0) images were fitted to a biexponential function and normalized. The signal-b curve is obtained by dividing the latter curve by the former. DH was obtained from the curve at b >4000 s/mm2 . A Monte-Carlo Simulation (MCS) was performed to investigate how DH changes upon the increased water-exchange at the CSC. RESULTS: The signal-b curves plotted at multiple levels of healthy CSC are almost identical on two successive scans and show a biexponential decay behavior: fast exponential decay at lower b-values and much slower decay at UHb-values. The mean values of DH were measured as (0.0607 ± 0.02531) ×10-3 and (0.0357 ± 0.02072) ×10-3 s/mm2 at the lateral funiculus and posterior column, respectively. MCS of diffusion MRI shows that the DH is elevated by increased water exchange between the intra- and extraaxonal spaces. DATA CONCLUSION: UHb-rDWI signal-b plots of the normal CSC were highly reproducible on successive scans and their biexponential decay behavior can be used to characterize normal spinal white matter. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:204-211.

Low b-value diffusion weighted imaging is promising in the diagnosis of brain death and hypoxic-ischemic injury secondary to cardiopulmonary arrest.

BACKGROUND: Cardiorespiratory arrest can result in a spectrum of hypoxic ischemic brain injury leading to global hypoperfusion and brain death (BD). Because up to 40% of patients with BD are viable organ donors, avoiding delayed diagnosis of this condition is critical. High b-value diffusion weighted imaging (DWI) measures primarily molecular self-diffusion; however, low b-values are sensitive to perfusion. We investigated the feasibility of low b-value DWI in discriminating the global hypoperfusion of BD and hypoxic ischemic encephalopathy (HIE). METHODS: We retrospectively reviewed cardiorespiratory arrest subjects with a diagnosis of HIE or BD. Inclusion criteria included brain DWI acquired at both low (50 s/mm2) and high (1000-2000 s/mm2) b-values. Automated segmentation was used to determine mean b50 apparent diffusion coefficient (ADC) values in gray and white matter regions. Normal subjects with DWI at both values were used as age- and sex-matched controls. RESULTS: We evaluated 64 patients (45 with cardiorespiratory arrest and 19 normal). Cardiorespiratory arrest patients with BD had markedly lower mean b50 ADC in gray matter regions compared with HIE (0.70 ± 0.18 vs. 1.95 ± 0.25 × 10-3 mm2/s, p < 0.001) and normal subjects (vs. 1.79 ± 0.12 × 10-3 mm2/s, p < 0.001). HIE had higher mean b50 ADC compared with normal (1.95 ± 0.25 vs. 1.79 ± 0.12 × 10-3 mm2/s, p = 0.016). There was wide separation of gray matter ADC values in BD subjects compared with age matched normal and HIE subjects. White matter values were also markedly decreased in the BD population, although they were less predictive than gray matter. CONCLUSION: Low b-value DWI is promising for the discrimination of HIE with maintained perfusion and brain death in cardiorespiratory arrest.

Two-dimensional single-shot diffusion-weighted stimulated EPI with reduced FOV for ultrahigh-b radial diffusion-weighted imaging of spinal cord.

PURPOSE: High-resolution diffusion-weighted imaging (DWI) of the spinal cord (SC) is problematic because of the small cross-section of the SC and the large field inhomogeneity. Obtaining the ultrahigh-b DWI poses a further challenge. The purpose of the study was to design and validate two-dimensional (2D) single-shot diffusion-weighted stimulated echo planar imaging with reduced field of view (2D ss-DWSTEPI-rFOV) for ultrahigh-b radial DWI (UHB-rDWI) of the SC. METHODS: A novel time-efficient 2D ss-DWSTEPI-rFOV sequence was developed based on the stimulated echo sequence. Reduced-phase field of view was obtained by using two slice-selective 90 ° radiofrequency pulses in the presence of the orthogonal slice selection gradients. The sequence was validated on a cylindrical phantom and demonstrated on SC imaging. RESULTS: Ultrahigh-b radial diffusion-weighted ( bmax = 7300 s/mm2) images of the SC with greatly reduced distortion were obtained. The exponential plus constant fitting of the diffusion-decay curve estimated the constant fraction (restricted water fraction) as 0.36 ± 0.05 in the SC white matter. CONCLUSION: A novel 2D ss-DWSTEPI-rFOV sequence has been designed and demonstrated for high-resolution UHB-rDWI of localized anatomic structures with significantly reduced distortion induced by nonlinear static field inhomogeneity. Magn Reson Med 77:2167-2173, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Do Superior or Inferior Interlaminar Approach or Bevel Orientation Predispose to Nonepidural Needle Penetration?

OBJECTIVE: There is a paucity of evidence-based literature regarding the advantages and disadvantages of the interlaminar approach and needle bevel orientation for performing a lumbar interlaminar epidural steroid injection (ESI). The purpose of this study was to determine if superior versus inferior lamina approach, needle bevel tip orientation, or both may predispose to inadvertent nonepidural penetration during lumbar interlaminar ESI. SUBJECTS AND METHODS: A prospective study was performed of patients with low back pain with or without radicular pain or neurogenic claudication referred for lumbar interlaminar ESI. Two hundred eleven patients were randomized by interlaminar approach (superior vs inferior) and bevel tip orientation (cranial vs caudal). Lumbar interlaminar ESI was performed by six interventionalists of varying levels of experience using fluoroscopic guidance with curved tip epidural needles, using loss-of-resistance technique and confirmation with contrast opacification. Exact Poisson regression was used to model the study outcome. RESULTS: Two hundred twenty-one lumbar interlaminar ESIs were performed on 211 patients, randomized to a superior (n = 121) or inferior lamina approach (n = 100) and to a cranial (n = 103) or caudal (n = 118) orientation of the bevel tip. Epidural needle placement was confirmed in 96.4% (n = 213) of cases. Nonepidural needle placement was most commonly associated with superior lamina approach and caudal bevel tip orientation, which was marginally significant (adjusted risk ratio, 6.88; 95% CI, 0.93-∞; p = 0.059). CONCLUSION: Inadvertent nonepidural needle penetration during fluoroscopically guided lumbar interlaminar ESI appears to be affected by approach, with superior lamina approach and caudal bevel tip orientation being the least favorable technique.

Acute traumatic intraosseous fluid sign predisposes to dynamic fracture mobility.

The intraosseous fluid sign (IFS) in chronic osteoporotic vertebral fractures is attributed to fluid accumulation within non-healing intervertebral clefts. IFS can also be seen in acute traumatic fractures, not previously described. We hypothesize a pathophysiological mechanism for the acute traumatic intraosseous fluid sign (ATIFS) and its predisposition to dynamic fracture mobility with axial loading on upright radiographs. Retrospective analysis was performed of 41 acute thoracic and lumbar compression or stable burst fractures with both supine CT and upright plain films completed within 1 week of each other. The presence of an intravertebral cleft with fluid attenuation and vertebral body height loss was assessed on CT scans. Changes in the fractured vertebral body height and angulation were measured on upright radiographs. The ATIFS was identified in 18 (44%) of the 41 acute fractures. Mean kyphotic angle increase was significantly greater (p = 0.000) for ATIFS fractures (8.2°, SD ±4.2) than fractures without ATIFS (1.6°, SD ±3.4). There was significantly greater mean anterior (p = 0.0009) and central (p = 0.026) height loss in ATIFS fractures (4.3 mm, SD ±3.76 and 1.89 mm, SD ±4.44, respectively) compared to fractures without ATIFS (0.59 mm, SD ±2.24 and -0.52 mm, SD ±2.01, respectively). The IFS can be seen in acute traumatic vertebral fractures and show dynamic mobility. These ATIFS fractures show statistically significant greater mean height loss ratio differences and have significantly greater changes in kyphotic angulation on upright imaging when compared to fractures without ATIFS.

Spinal Neuroarthropathy: Pathophysiology, Clinical and Imaging Features, and Differential Diagnosis.

Spinal neuroarthropathy (SNA), or Charcot spine, is a progressive destructive arthropathy occurring after loss of neuroprotective sensation and proprioceptive reflexes. Clinical diagnosis is difficult because of the variable length to presentation after initial neurologic damage and the limited symptoms given preexisting neurologic deficits. SNA is also a diagnostic challenge because its imaging features are similar to those of spinal conditions such as discitis-osteomyelitis, osseous tuberculosis, hemodialysis-related spondyloarthropathy, and pseudarthrosis. The most important imaging clues for diagnosis of SNA are involvement of both anterior and posterior elements at the thoracolumbar and lumbosacral junctions. Additional imaging clues include vacuum phenomenon within the disk (indicating excessive motion), malalignment, and paraspinal soft-tissue masses or fluid collections containing bone debris. Despite these imaging signs, findings may overlap in some cases with those of infection, or SNA can be superinfected, and biopsy may be necessary. Development of SNA requires a preexisting neurologic condition, most commonly traumatic spinal cord injury. Areas of greatest mobility and weight bearing within the desensate spine experience repetitive microtrauma and unregulated hyperemia, leading to destruction of the intervertebral articulations. The progressive and destructive nature of SNA causes substantial deformity, loss of function, and often further neurologic deficits. Patients present with deformity, back pain, audible noises during movement, or new neurologic symptoms. The mainstay of treatment is surgical débridement, reduction, and fusion. The radiologist can help initiate early intervention by using key imaging features to distinguish SNA from imaging mimics and prevent further neurologic deterioration. (©)RSNA, 2016.

MR-Guided Focused Ultrasound Thalamotomy in the Setting of Aneurysm Clip.

We report on a 75-year-old woman with a history of right MCA aneurysm clipping and medically refractive right-hand tremor. We successfully performed focused ultrasound thalamotomy of the left ventral intermediate nucleus under MR imaging-guidance at 3T. A thorough pretreatment evaluation of MR thermometry was critical to ensure that adequate precision could be achieved at the intended target. The tremor showed a 75% decrease at 24 hours postprocedure and a 50% decrease at a 3-month follow-up. There were no immediate adverse events.

Diagnostic and Therapeutic Challenges of Rare Concurrent Intracranial Meningioma and Oligodendroglioma.

Introduction: Concurrent primary brain tumors are rare clinical entities, with a prevalence ranging from 0.1 to 0.5% of all diagnosed brain tumors. The co-occurrence of meningioma and oligodendroglioma is particularly uncommon, posing unique diagnostic and therapeutic challenges. We describe the case of a patient diagnosed with concurrent meningioma and oligodendroglioma and review the existing literature on this rare phenomenon. Case Presentation: A 55-year-old female patient with a history of seizures presented to the emergency department with worsening headaches, nausea, and vomiting. She had a known right frontoparietal intracranial mass but had previously declined surgery. Magnetic resonance imaging revealed extensive fluid-attenuated inversion recovery /T2 hyperintensity around the lesion, which had slowly increased over 5 years; the growth of the lesion was producing a mass effect with a significant midline shift. The patient underwent urgent hemicraniectomy with subsequent resection. Clinical evaluation, imaging studies, and histopathological examination were conducted to confirm the diagnosis. Genetic and molecular analyses were also performed to explore potential underlying mechanisms. Histopathological findings confirmed a diagnosis of an isocitrate dehydrogenase-mutated World Health Organization Grade II oligodendroglioma with 1p/19q codeletion, along with a Grade I meningioma. Conclusion: The coexistence of meningioma and oligodendroglioma represents a rare clinical event. Surgical management remains the cornerstone of treatment. Further investigation into the genetic and environmental factors that contribute to the co-occurrence of such tumors could pave the way for more targeted therapeutic strategies.

The Treatment of Symptomatic Diffuse Proliferative Cerebral Angiopathy With Cilostazol: A Case Report.

Diffuse proliferative cerebral angiopathy (DPCA) is a rare form of cerebral vascular malformation responsible for 3.4% of all cerebral arteriovenous malformations (AVMs). The relative risk of rupture for DPCA is lower than for classic AVMs, so they are often managed medically. Despite the somewhat lower rupture risk, the risk of rebleeding is paradoxically higher than in classical AVMs, and there is a potential for significant morbidity and mortality. The aim of this article is to describe a case of a patient with symptomatic DPCA who experienced symptomatic improvement after treatment with the vasodilating agent cilostazol. This is a case report of a patient who presented with aphasia and was found to have DPCA. CT perfusion with acetazolamide challenge confirmed that the patient's symptoms were due to steal phenomena. Subsequently, the patient was treated with 50 mg of cilostazol daily to mediate a vasodilatory response within the arterial tree. Within three days of treatment with cilostazol, the patient showed significant improvement in his aphasia. The patient returned to the clinic a month later and reported continued improvement in his aphasia with speech therapy. Patients who present with neurological deficits from steal phenomena caused by DPCA are difficult to treat surgically because DPCAs often involve normal parenchyma. We present an example of a noninterventional alternative, oral cilostazol paired with functional rehabilitation, for alleviating symptoms associated with DPCA.

Disparities in Provider Ordering Practices of Image-Guided Interventions and Surgery for Patients With Low Back Pain: A Cohort Study.

OBJECTIVE: To assess individual- and neighborhood-level sociodemographic factors associating with providers' ordering of nonpharmacologic treatments for patients with low back pain (LBP), specifically physical therapy, image-guided interventions, and lumbar surgery. METHODS: Our cohort included all patients diagnosed with LBP from 2000 to 2017 in a statewide database of all hospitals and ambulatory surgical facilities within Utah. We compared sociodemographic and clinical characteristics of (1) patients with LBP who received any treatment with those who received none and (2) patients with LBP who received invasive LBP treatments with those who only received noninvasive LBP treatments using the Student's t test, Wilcoxon's rank-sum tests, and Pearson's χ2 tests, as applicable, and two separate multivariate logistic regression models: (1) to determine whether sociodemographic characteristics were risk factors for receiving any LBP treatments and (2) risk factors for receiving invasive LBP treatments. RESULTS: Individuals in the most disadvantaged neighborhoods were less likely to receive any nonpharmacologic treatment orders (odds ratio [OR] 0.74 for most disadvantaged, P < .001) and received fewer invasive therapies (0.92, P = .018). Individual-level characteristics correlating with lower rates of treatment orders were female sex, Native Hawaiian or other Pacific Islander race (OR 0.50, P < .001), Hispanic ethnicity (OR 0.77, P < .001), single or unmarried status (OR 0.69, P < .001), and no insurance or self-pay (OR 0.07, P < .001). CONCLUSION: Neighborhood and individual sociodemographic variables associated with treatment orders for LBP with Area Deprivation Index, sex, race or ethnicity, insurance, and marital status associating with receipt of any treatment, as well as more invasive image-guided interventions and surgery.

The Brain Tumor Segmentation (BraTS) Challenge 2023: Focus on Pediatrics (CBTN-CONNECT-DIPGR-ASNR-MICCAI BraTS-PEDs).

Pediatric tumors of the central nervous system are the most common cause of cancer-related death in children. The five-year survival rate for high-grade gliomas in children is less than 20%. Due to their rarity, the diagnosis of these entities is often delayed, their treatment is mainly based on historic treatment concepts, and clinical trials require multi-institutional collaborations. The MICCAI Brain Tumor Segmentation (BraTS) Challenge is a landmark community benchmark event with a successful history of 12 years of resource creation for the segmentation and analysis of adult glioma. Here we present the CBTN-CONNECT-DIPGR-ASNR-MICCAI BraTS-PEDs 2023 challenge, which represents the first BraTS challenge focused on pediatric brain tumors with data acquired across multiple international consortia dedicated to pediatric neuro-oncology and clinical trials. The BraTS-PEDs 2023 challenge focuses on benchmarking the development of volumentric segmentation algorithms for pediatric brain glioma through standardized quantitative performance evaluation metrics utilized across the BraTS 2023 cluster of challenges. Models gaining knowledge from the BraTS-PEDs multi-parametric structural MRI (mpMRI) training data will be evaluated on separate validation and unseen test mpMRI dataof high-grade pediatric glioma. The CBTN-CONNECT-DIPGR-ASNR-MICCAI BraTS-PEDs 2023 challenge brings together clinicians and AI/imaging scientists to lead to faster development of automated segmentation techniques that could benefit clinical trials, and ultimately the care of children with brain tumors.

Intracranial hypotension: improved MRI detection with diagnostic intracranial angles.

OBJECTIVE: Intracranial hypotension is an uncommon cause of headaches that is often misdiagnosed. The classic MRI features of intracranial hypotension can be variable and subjective. The purpose of this study was to provide objective criteria in the MRI evaluation of intracranial hypotension by quantifying normal values for the pontomesencephalic angle, mamillopontine distance, and lateral ventricular angle. MATERIALS AND METHODS: A retrospective review of patients with the clinical diagnosis of intracranial hypotension and a control group was performed with measurements of the pontomesencephalic angle, mamillopontine distance, and lateral ventricular angle. Qualitative evaluation of other MRI findings included dural enhancement, venous engorgement, subdural collections, brainstem slumping, and tonsillar herniation. RESULTS: In 29 patients with intracranial hypotension, the mean pontomesencephalic angle, mamillopontine distance, and lateral ventricular angle were 41.2° (SD, ± 17.4°), 4.4 mm (SD, ± 1.8), and 130.1° (SD, ± 9.8°), respectively. In the control group, the mean pontomesencephalic angle, mamillopontine distance, and lateral ventricular angle were 65° (SD, ± 9.9°), 7.0 mm (SD, ± 1.3), and 132.2° (SD, ± 5.7°), respectively. The differences in the pontomesencephalic angle and mamillopontine distance values for the intracranial hypotension group versus the control group were statistically significant (p < 0.01). The difference in the lateral ventricular angle measurements was not statistically significant (p = 0.37). Cutoff points of a 5.5-mm mamillopontine distance and 50° pontomesencephalic angle were estimated using receiver operating characteristic curves. CONCLUSION: In patients with the clinical suspicion of intracranial hypotension, we found that cutoff values of 5.5 mm or less for the mamillopontine distance and 50° or less for the pontomesencephalic angle were sensitive and specific in strengthening the qualitative MRI findings. Therefore, quantitative assessments may provide a more accurate diagnosis.

Mastoid findings secondary to posterior fossa dural venous sinus thrombosis.

OBJECTIVE: In the setting of posterior fossa dural venous sinus thrombosis, mastoid findings can potentially be mistaken as the cause rather than a secondary effect. Obstruction of the mastoid venous drainage can lead to transudation of fluid into the mastoid air cells. We hypothesize that a continuum of the mastoid manifestations secondary to dural venous sinus thrombosis can be seen on MRI and that the difference in venous drainage between the mastoid and middle ears can assist with this important imaging differential. MATERIALS AND METHODS: A retrospective review of acute dural venous sinus thrombosis cases and their follow-up imaging were graded as follows: no involvement; grade 1 mucosal congestion; grade 2, film of fluid; or grade 3, complete opacification. Presence of middle ear fluid was also documented. RESULTS: Of 22 posterior fossa dural venous sinus thrombosis cases without clinical infectious mastoiditis, 19 had mastoid findings: eight with grade 1, eight with grade 2, and three with grade 3. Middle ear fluid was seen in only one case. There was a statistically significant association between posterior fossa dural venous sinus thrombosis and mastoid findings (chisquare test (n = 22), p < 0.04). Fifteen of 18 cases with follow-up MRI examinations showed lessening of the mastoid findings with resolving dural venous sinus thrombosis. CONCLUSION: Acute posterior fossa dural venous sinus thrombosis may present with a spectrum of mastoid findings that should not be misdiagnosed as the cause of the thrombosis. This study illustrates that in the absence of clinical findings of mastoiditis, mastoid fluid with a clear middle ear argues that the mastoid changes are the effect of the dural venous sinus thrombosis rather than the cause.

Noncontrast computed tomographic Hounsfield unit evaluation of cerebral venous thrombosis: a quantitative evaluation.

INTRODUCTION: Our objective is to determine the utility of noncontrast Hounsfield unit values, Hounsfield unit values corrected for the patient's hematocrit, and venoarterial Hounsfield unit difference measurements in the identification of intracranial venous thrombosis on noncontrast head computed tomography. METHODS: We retrospectively reviewed noncontrast head computed tomography exams performed in both normal patients and those with cerebral venous thrombosis, acquiring Hounsfield unit values in normal and thrombosed cerebral venous structures. Also, we acquired Hounsfield unit values in the internal carotid artery for comparison to thrombosed and nonthrombosed venous structures and compared the venous Hounsfield unit values to the patient's hematocrit. RESULTS: A significant difference is identified between Hounsfield unit values in thrombosed and nonthrombosed venous structures. Applying Hounsfield unit threshold values of greater than 65, a Hounsfield unit to hematocrit ratio of greater than 1.7, and venoarterial difference values greater than 15 alone and in combination, the majority of cases of venous thrombosis are identifiable on noncontrast head computed tomography. CONCLUSION: Absolute Hounsfield unit values, Hounsfield unit to hematocrit ratios, and venoarterial Hounsfield unit value differences are a useful adjunct in noncontrast head computed tomographic evaluation of cerebral venous thrombosis.

Conventional and Advanced Imaging of Spinal Cord Tumors.

Spinal cord tumors are best identified by conventional MR imaging with contrast. Most intramedullary spinal cord tumors have characteristic MR imaging features that allow an accurate preoperative diagnosis. The spinal cord tumors reviewed in this article include the most common tumors, ependymomas and astrocytomas, as well as the less common tumors such as hemangioblastomas and metastases. Rare tumors such as primary CNS lymphoma and melanocytic tumors are also described. Advanced imaging techqniques of more common intramedullary tumors are also reviewed.