Relevance of asymptomatic spinal MRI lesions in patients with multiple sclerosis.

BACKGROUND: The impact of new asymptomatic spinal cord lesions (a-SL) in multiple sclerosis (MS) course is poorly characterized. OBJECTIVE: The objective of this research paper is to assess the prognostic value of a-SL in predicting MS course. METHODS: Relapsing-remitting MS patients who received serial MRI (brain and spinal) at baseline (t1) and within 12 to 36 months (t2) during clinical stability, and had a follow-up (t2-t3) ⩾24 months were included. Relapses and disability progression were evaluated between t2 and t3. RESULTS: Of 413 consecutive screened MS patients, 103 patients (65 females, median age 43 years) were included. After a median t1-t2 interval of 17 (IQR 13-26) months, 25.2% and 43.7% patients had ⩾1 new a-SL (a-SL+) and asymptomatic brain lesions (a-BL+), respectively. Relapse risk between t2 and t3 (median interval: 42 (IQR 32-57.5) months) was significantly increased in a-SL+ and/or a-BL+ vs a-BL- and a-SL- (HR = 2.31, 95% CI = 1.13-4.72, p = 0.02). No differences in the risk of disability progression were found in a-SL+ and/or a-BL+ vs a-SL- and a-BL-. CONCLUSION: a-SL occur in one-quarter of clinically stable RRMS, and combined with a-BL contribute significantly in predicting future disease course.

AN EXTENDED FOLLOW-UP OF SPINAL INSTRUMENTATION RESCUE WITH CEMENT AUGMENTATION.

BACKGROUND AND PURPOSE: Percutaneous cement augmentation has been reported as an effective salvage procedure for frail patients suffering with spinal instrumentation failure, such as screw loosening, hardware breakage, cage subsidence, and fractures within or adjacent to stabilized segments. Favorable results were reported over a median follow-up period of 16 months in a retrospective analysis of 31 consecutive procedures performed in 29 patients. In the present study, the long-term effectiveness of this treatment in avoiding or postponing revision surgery is reported. MATERIALS AND METHODS: Clinical and radiological data of our original cohort of patients were retrospectively collected and reviewed to provide an extended follow-up assessment. The need for revision spinal surgery was assessed as the primary outcome and the radiological stability of the augmented spinal implants was considered as the secondary outcome. RESULTS: An extended radiological follow-up was available in 27/29 patients with an average of 50.9 months. Overall, 18/27 (66.7%) patients, originally candidates for revision surgery, avoided a surgical intervention after a cement augmentation rescue procedure. In the remaining patients, the average interval between the rescue cement augmentation and the revision surgery was 22.5 months. Implant mobilization occurred in 2/27 (7.4%) patients, rod breakage in 1/27 (3.7%), a new fracture within or adjacent to the instrumented segment occurred in 4/27 (14.8%) patients and screw loosening at rescued levels occurred in 5/27 (18.5%) patients. CONCLUSIONS: In this cohort, cement augmentation rescue procedures were found to be effective in avoiding or postponing revision surgery during long-term follow up. ABBREVIATIONS: N/A.

Comparison between CT and MR in perfusion imaging assessment of high-grade gliomas.

PURPOSE: The aim of our study was to compare the relative cerebral blood volume (CBV) values obtained by first-pass dynamic susceptibility-weighted contrast-enhanced (DSC) T2-weighted magnetic resonance (MR) and perfusion computed tomography (P-CT) imaging in high-grade gliomas (HGG) in the same patient population. MATERIALS AND METHODS: Sixteen patients with histologically proven HGG underwent P-CT and DSC-MR brain imaging. P-CT studies were obtained using a four-row multislice CT scanner and postprocessed with a commercial software package based on a deconvolution-based technique. DSC-MR images were obtained at 1.5 T with a first-pass dynamic susceptibility contrast-enhanced T2-weighted sequence. P-CT and DSC-MR images were obtained within 4 days of each another, always before surgery. Maximum CBV ratios normalised with contralateral white matter (rCBV) were calculated. Statistical analysis was performed with the classical parametric statistic procedure. RESULTS: A linear correlation between maximum rCBV values obtained with P-CT and DSC-MR imaging was evident. The best linear model is CT=slope×MR+error and provides a highly significant estimate of the slope equal to 1.08. Thus CT results can be predicted from MR values. Therefore, it is also possible to predict MR results from CT values by estimating the linear model MR=slope×CT+error. DSC-MR imaging gave lower rCBV average values (4.92±1.52) compared with P-CT (5.56±1.55). CONCLUSIONS: In our population of patients, P-CT and DSC-MR imaging showed proportional results in rCBV assessment of HGGs, and thus both modalities may be used interchangeably in HGG of the brain.

Minimally Invasive Stent Screw-Assisted Internal Fixation Technique Corrects Kyphosis in Osteoporotic Vertebral Fractures with Severe Collapse: A Pilot "Vertebra Plana" Series.

BACKGROUND AND PURPOSE: Fractures with "vertebra plana" morphology are characterized by severe vertebral body collapse and segmental kyphosis; there is no established treatment standard for these fractures. Vertebroplasty and balloon kyphoplasty might represent an undertreatment, but surgical stabilization is challenging in an often elderly osteoporotic population. This study assessed the feasibility, clinical outcome, and radiologic outcome of the stent screw-assisted internal fixation technique using a percutaneous implant of vertebral body stents and cement-augmented pedicle screws in patients with non-neoplastic vertebra plana fractures. MATERIALS AND METHODS: Thirty-seven consecutive patients with vertebra plana fractures were treated with the stent screw-assisted internal fixation technique. Vertebral body height, local and vertebral kyphotic angles, outcome scales (numeric rating scale and the Patient's Global Impression of Change), and complications were assessed. Imaging and clinical follow-up were obtained at 1 and 6 months postprocedure. RESULTS: Median vertebral body height restoration was 7 mm (+74%), 9 mm (+150%), and 3 mm (+17%) at the anterior wall, middle body, and posterior wall, respectively. Median local and vertebral kyphotic angles correction was 8° and 10° and was maintained through the 6-month follow-up. The median numeric rating scale score improved from 8/10 preprocedure to 3/10 at 1 and 6 months (P < .001). No procedural complications occurred. CONCLUSIONS: The stent screw-assisted internal fixation technique was effective in obtaining height restoration, kyphosis correction, and pain relief in patients with severe vertebral collapse.

Stroke Mimics in the Acute Setting: Role of Multimodal CT Protocol.

BACKGROUND AND PURPOSE: Ischemic stroke can be mimicked by nonischemic conditions. Due to emphasis on the rapid treatment of acute ischemic stroke, it is crucial to identify these conditions to avoid unnecessary therapies and potential complications. We investigated the performance of the multimodal CT protocol (unenhanced brain CT, CTA, and CTP) to discriminate stroke mimics from acute ischemic stroke. MATERIALS AND METHODS: We retrospectively selected multimodal CT studies performed for clinical suspicion of acute ischemic stroke in our center in a 24-month period, including patients with at least 1 follow-up imaging study (brain CT or MR imaging). Hemorrhagic strokes were excluded. We measured the performance of multimodal CT, comparing the original diagnostic results with the final clinical diagnosis at discharge. RESULTS: Among 401 patients, a stroke mimic condition was diagnosed in 89 (22%), including seizures (34.8%), migraine with aura attack (12.4%), conversion disorder (12.4%), infection (7.9%), brain tumor (7.9%), acute metabolic condition (6.7%), peripheral vertigo (5.6%), syncope (5.6%), transient global amnesia (3.4%), subdural hematoma (1.1%), cervical epidural hematoma (1.1%), and dural AVF (1.1%). Multimodal CT sensitivity, specificity, and accuracy were 24.7%, 99.7%, and 83%. Multimodal CT revealed peri-ictal changes in 13/31 seizures and diagnosed 7/7 brain tumors, 1/1 dural AVF, and 1/1 subdural hematoma. CT perfusion played a pivotal diagnostic role. CONCLUSIONS: Multimodal CT demonstrated low sensitivity but high specificity in the diagnosis of stroke mimics in the acute setting. The high specificity of multimodal CT allows ruling out stroke and thereby avoiding unnecessary revascularization treatment in patients with diagnosis of a stroke mimic.

Nonlesional Sources of Contrast Enhancement on Postgadolinium "Black-Blood" 3D T1-SPACE Images in Patients with Multiple Sclerosis.

BACKGROUND AND PURPOSE: We hypothesized that 3D T1-TSE "black-blood" images may carry an increased risk of contrast-enhancing lesion misdiagnosis in patients with MS because of the misinterpretation of intraparenchymal vein enhancement. Thus, the occurrence of true-positive and false-positive findings was compared between standard MPRAGE and volumetric interpolated brain examination techniques. MATERIALS AND METHODS: Sampling perfection with application-optimized contrasts by using different flip-angle evolution (SPACE) images obtained from 232 patients with MS, clinically isolated syndrome, or radiologically isolated syndrome were compared with standard MPRAGE and volumetric interpolated brain examination images. The intraparenchymal vein contrast-to-noise ratio was estimated at the level of the thalami. Contrast-enhancing lesions were blindly detected by 2 expert readers and 1 beginner reader. True- and false-positives were determined by senior readers' consensus. True-positive and false-positive frequency differences and patient-level diagnosis probability were tested with the McNemar test and OR. The contrast-to-noise ratio and morphology were compared using the Mann-Whitney U and χ2 tests. RESULTS: The intraparenchymal vein contrast-to-noise ratio was higher in SPACE than in MPRAGE and volumetric interpolated brain examination images (P < .001, both). There were 66 true-positives and 74 false-positives overall. SPACE detected more true-positive and false-positive results (P range < .001-.07) but did not increase the patient's true-positive likelihood (OR = 1 1.29, P = .478-1). However, the false-positive likelihood was increased (OR = 3.03-3.55, P = .008-.027). Venous-origin false-positives (n = 59) with contrast-to-noise ratio and morphology features similar to small-sized (≤14 mm3 P = .544) true-positives occurred more frequently in SPACE images (P < .001). CONCLUSIONS: Small intraparenchymal veins may confound the diagnosis of enhancing lesions on postgadolinium black-blood SPACE images.

Motor cortex plasticity predicts recovery in acute stroke.

Repetitive transcranial magnetic stimulation of the brain given as intermittent theta burst stimulation (iTBS) can induce long-term potentiation (LTP)-like changes in the stimulated hemisphere and long-term depression (LTD)-like changes in the opposite hemisphere. We evaluated whether LTP- and LTD-like changes produced by iTBS in acute stroke correlate with outcome at 6 months. We evaluated the excitability of affected hemisphere (AH) and unaffected hemisphere (UH) by measuring motor threshold and motor-evoked potential (MEP) amplitude under baseline conditions and after iTBS of AH in 17 patients with acute ischemic stroke. Baseline amplitude of MEPs elicited from AH was significantly smaller than that of MEPs elicited from UH, and baseline motor threshold was higher for the AH. Higher baseline MEP values in UH correlated with poor prognosis. iTBS produced a significant increase in MEP amplitude for AH that was significantly correlated with recovery. A nonsignificant decrease in MEP amplitude was observed for the UH. When the decrease in the amplitude of UH MEPs was added to the regression model, the correlation was even higher. Functional recovery is directly correlated with LTP-like changes in AH and LTD-like changes in UH and inversely correlated with the baseline excitability of UH.

Clinical pitfalls related to short and long echo times in cerebral MR spectroscopy.

MR-spectroscopy (MRS) is a multiparameter diagnostic tool and modification of each parameter results in spectrum morphology changes. In particular, changing the echo time (TE) represents a useful tool to highlight different diagnostic elements, but also has significant impact on the spectrum morphology. Diagnostic errors can result if the role of TE is not properly considered. This article reviews the four most common TE-related pitfalls of MRS interpretation. Clinical practical methods to avoid such pitfalls are also suggested.

Dedicated 3D-T2-STIR-ZOOMit Imaging Improves Demyelinating Lesion Detection in the Anterior Visual Pathways of Patients with Multiple Sclerosis.

BACKGROUND AND PURPOSE: Demyelinating lesions in the anterior visual pathways represent an underestimated marker of disease dissemination in patients with MS. We prospectively investigated whether a dedicated high-resolution MR imaging technique, the 3D-T2-STIR-ZOOMit, improves demyelinating lesion detection compared with the current clinical standard sequence, the 2D-T2-STIR. MATERIALS AND METHODS: 3T MR imaging of the anterior visual pathways (optic nerves, chiasm, and tracts) was performed using 3D-T2-STIR-ZOOMit and 2D-T2-STIR, in patients with MS and healthy controls. Two experienced neuroradiologists assessed, independently, demyelinating lesions using both sequences separately. 3D-T2-STIR-ZOOMit scan-rescan reproducibility was tested in 12 patients. The Cohen κ was used for interrater agreement, and the intraclass correlation coefficient for reproducibility. Between-sequence detection differences and the effects of location and previous acute optic neuritis were assessed using a binomial mixed-effects model. RESULTS: Forty-eight patients with MS with (n = 19) or without (n = 29) past optic neuritis and 19 healthy controls were evaluated. Readers' agreement was strong (3D-T2-STIR-ZOOMit: 0.85; 2D-T2-STIR: 0.90). The 3D-T2-STIR-ZOOMit scan-rescan intraclass correlation coefficient was 0.97 (95% CI, 0.96-0.98; P < .001), indicating excellent reproducibility. Overall, 3D-T2-STIR-ZOOMit detected more than twice the demyelinating lesions (n = 89) than 2D-T2-STIR (n = 43) (OR = 2.7; 95% CI, 1.7-4.1; P < .001). In the intracranial anterior visual pathway segments, 33 of the 36 demyelinating lesions (91.7%) detected by 3D-T2-STIR-ZOOMit were not disclosed by 2D-T2-STIR. 3D-T2-STIR-ZOOMit increased detection of demyelinating lesion probability by 1.8-fold in patients with past optic neuritis (OR = 1.8; 95% CI, 1.2-3.1; P = .01) and 5.9-fold in patients without past optic neuritis (OR = 5.9; 95% CI, 2.5-13.8; P < .001). No false-positive demyelinating lesions were detected in healthy controls. CONCLUSIONS: Dedicated 3D-T2-STIR-ZOOMit images improved substantially the detection of MS disease dissemination in the anterior visual pathways, particularly in the intracranial segments and in patients without past optic neuritis.

Endovascular Thrombectomy of Calcified Emboli in Acute Ischemic Stroke: A Multicenter Study.

BACKGROUND AND PURPOSE: Large intracranial vessel occlusion due to calcified emboli is a rare cause of major stroke. We assessed the prevalence, imaging appearance, the effectiveness of mechanical thrombectomy, and clinical outcome of patients with large-vessel occlusion due to calcified emboli. MATERIALS AND METHODS: We performed a retrospective analysis of clinical and procedural data of consecutive patients who underwent mechanical thrombectomy due to calcified emboli in 7 European stroke centers. RESULTS: We screened 2969 patients, and 40 patients matched the inclusion criteria, accounting for a prevalence of 1.3%. The mean maximal density of the thrombus was 327 HU (range, 150-1200 HU), and the mean thrombus length was 9.2 mm (range, 4-20 mm). Four patients had multiple calcified emboli, and 2 patients had an embolic event during an endovascular intervention. A modified TICI score of ≥2b was achieved in 57.5% (23/40), with minimal-to-no reperfusion (modified TICI 0-1) in 32.5% (13/40) and incomplete reperfusion (modified TICI 2a) in 10% (4/40). Excellent outcome (mRS 0-1) was achieved in only 20.6%, functional independence (mRS 0-2) in 26.5% and 90-day mortality was 55.9%. CONCLUSIONS: Acute ischemic stroke with large-vessel occlusion due to calcified emboli is a rare entity in patients undergoing thrombectomy, with considerably worse angiographic outcome and a higher mortality compared with patients with noncalcified thrombi. Good functional recovery at 3 months can still be achieved in about a quarter of patients.

Central pontine and extrapontine myelinolysis in a pediatric patient following rapid correction of hypernatremia.

Central pontine and extrapontine myelinolysis are uncommon disorders characterized by distinctive clinical features and typical findings on neuroimaging. Only a few cases are reported in the pediatric age group. We describe the case of a leukemic, malnourished 14-year-old boy with a high serum sodium concentration that gradually increased to 170 mmol/L. During a septic shock episode, hydration with a low sodium concentration at the rate of 104 mL/h for 24 h was administered. A rapid correction of the high serum sodium occurred, exceeding 0.5 mmol/L/h. The following day the patient developed rapid and progressive neurological impairment with clinical features characteristic of central pontine and extrapontine myelinolysis. Magnetic resonance imaging confirmed the diagnosis 11 days later. The patient was treated with steroids and intravenous immunoglobulins. He achieved an almost full neurological recovery and radiological improvement. The reported case demonstrates that central pontine and extrapontine myelinolysis can occur after excessively rapid correction of hypernatremia.

Armed Kyphoplasty: An Indirect Central Canal Decompression Technique in Burst Fractures.

BACKGROUND AND PURPOSE: Burst fractures are characterized by middle column disruption and may feature posterior wall retropulsion. Indications for treatment remain controversial. Recently introduced vertebral augmentation techniques using intravertebral distraction devices, such as vertebral body stents and SpineJack, could be effective in fracture reduction and fixation and might obtain central canal clearance through ligamentotaxis. This study assesses the results of armed kyphoplasty using vertebral body stents or SpineJack in traumatic, osteoporotic, and neoplastic burst fractures with respect to vertebral body height restoration and correction of posterior wall retropulsion. MATERIALS AND METHODS: This was a retrospective assessment of 53 burst fractures with posterior wall retropulsion and no neurologic deficit in 51 consecutive patients treated with armed kyphoplasty. Posterior wall retropulsion and vertebral body height were measured on pre- and postprocedural CT. Clinical and radiologic follow-up charts were reviewed. RESULTS: Armed kyphoplasty was performed as a stand-alone treatment in 43 patients, combined with posterior instrumentation in 8 and laminectomy in 4. Pre-armed kyphoplasty and post-armed kyphoplasty mean posterior wall retropulsion was 5.8 and 4.5 mm, respectively (P < .001), and mean vertebral body height was 10.8 and 16.7 mm, respectively (P < .001). No significant clinical complications occurred. Clinical and radiologic follow-up (1-36 months; mean, 8 months) was available in 39 patients. Three treated levels showed a new fracture during follow-up without neurologic deterioration, and no retreatment was deemed necessary. CONCLUSIONS: In the treatment of burst fractures with posterior wall retropulsion and no neurologic deficit, armed kyphoplasty yields fracture reduction, internal fixation, and indirect central canal decompression. In selected cases, it might represent a suitable minimally invasive treatment option, stand-alone or in combination with posterior stabilization.

Brain Tumor-Enhancement Visualization and Morphometric Assessment: A Comparison of MPRAGE, SPACE, and VIBE MRI Techniques.

BACKGROUND AND PURPOSE: Postgadolinium MR imaging is crucial for brain tumor diagnosis and morphometric assessment. We compared brain tumor enhancement visualization and the "target" object morphometry obtained with the most commonly used 3D MR imaging technique, MPRAGE, with 2 other routinely available techniques: sampling perfection with application-optimized contrasts by using different flip angle evolutions (SPACE) and volumetric interpolated brain examination (VIBE). MATERIALS AND METHODS: Fifty-four contrast-enhancing tumors (38 gliomas and 16 metastases) were assessed using MPRAGE, VIBE, and SPACE techniques randomly acquired after gadolinium-based contrast agent administration on a 3T scanner. Enhancement conspicuity was assessed quantitatively by calculating the contrast rate and contrast-to-noise ratio, and qualitatively, by consensus visual comparative ratings. The total enhancing tumor volume and between-sequence discrepancy in the margin delineation were assessed on the corresponding 3D target objects contoured with a computer-assisted software for neuronavigation. The Wilcoxon signed rank and Pearson χ2 nonparametric tests were used to investigate between-sequence discrepancies in the contrast rate, contrast-to-noise ratio, visual conspicuity ratings, tumor volume, and margin delineation estimates. Differences were also tested for 1D (Response Evaluation Criteria in Solid Tumors) and 2D (Response Assessment in Neuro-Oncology) measurements. RESULTS: Compared with MPRAGE, both SPACE and VIBE obtained higher contrast rate, contrast-to-noise ratio, and visual conspicuity ratings in both gliomas and metastases (P range, <.001-.001). The between-sequence 3D target object margin discrepancy ranged between 3% and 19.9% of lesion tumor volume. Larger tumor volumes, 1D and 2D measurements were obtained with SPACE (P range, <.01-.007). CONCLUSIONS: Superior conspicuity for brain tumor enhancement can be achieved using SPACE and VIBE techniques, compared with MPRAGE. Discrepancies were also detected when assessing target object size and morphology, with SPACE providing more accurate estimates.

Modulating cortical excitability in acute stroke: a repetitive TMS study.

OBJECTIVE: Changes in cerebral cortex excitability have been demonstrated after a stroke and are considered relevant for recovery. Repetitive transcranial magnetic stimulation (rTMS) of the brain can modulate cerebral cortex excitability and, when rTMS is given as theta burst stimulation (TBS), LTP- or LTD-like changes can be induced. The aim of present study was to evaluate the effects of TBS on cortical excitability in acute stroke. METHODS: In 12 acute stroke patients, we explored the effects of facilitatory TBS of the affected hemisphere and of inhibitory TBS of the unaffected hemisphere on cortical excitability to single-pulse transcranial magnetic stimulation (TMS) on both sides. The effects produced by TBS in patients were compared with those observed in a control group of age-matched healthy individuals. RESULTS: In patients, both the facilitatory TBS of the affected motor cortex and the inhibitory TBS of the unaffected motor cortex produced a significant increase of the amplitude of MEPs evoked by stimulation of the affected hemisphere. The effects observed in patients were comparable to those observed in controls. CONCLUSIONS: Facilitatory TBS over the stroke hemisphere and inhibitory TBS over the intact hemisphere in acute phase enhance the excitability of the lesioned motor cortex. SIGNIFICANCE: TBS might be useful to promote cortical plasticity in stroke patients.

Morphological and functional MR imaging of Lhermitte-Duclos disease with pathology correlate.

Lhermitte-Duclos disease (LDD) is a rare benign lesion of uncertain pathogenesis characterised by distortion of the normal cerebellar laminar cytoarchitecture. We report a case of LDD thoroughly characterized by advanced magnetic resonance imaging techniques, with diffusion-weighted, perfusion-weighted and post-gadolinium sequences. Imaging showed restricted diffusion consistent with high cellularity, high degree of vascularity and preserved blood-brain barrier permeability, correlating with pathology.

Spinal Instrumentation Rescue with Cement Augmentation.

BACKGROUND AND PURPOSE: Altered biomechanics or bone fragility or both contribute to spine instrumentation failure. Although revision surgery is frequently required, minimally invasive alternatives may be feasible. We report the largest to-date series of percutaneous fluoroscopically guided vertebral cement augmentation procedures to address feasibility, safety, results and a variety of spinal instrumentation failure conditions. MATERIALS AND METHODS: A consecutive series of 31 fluoroscopically guided vertebral augmentation procedures in 29 patients were performed to address screw loosening (42 screws), cage subsidence (7 cages), and fracture within (12 cases) or adjacent to (11 cases) the instrumented segment. Instrumentation failure was deemed clinically relevant when resulting in pain or jeopardizing spinal biomechanical stability. The main study end point was the rate of revision surgery avoidance; feasibility and safety were assessed by prospective recording of periprocedural technical and clinical complications; and clinical effect was measured at 1 month with the Patient Global Impression of Change score. RESULTS: All except 1 procedure was technically feasible. No periprocedural complications occurred. Clinical and radiologic follow-up was available in 28 patients (median, 16 months) and 30 procedures. Revision surgery was avoided in 23/28 (82%) patients, and a global clinical benefit (Patient Global Impression of Change, 5-7) was reported in 26/30 (87%) cases at 1-month follow-up, while no substantial change (Patient Global Impression of Change, 4) was reported in 3/30 (10%), and worsening status (Patient Global Impression of Change, 3), in 1/30 (3%). CONCLUSIONS: Our experience supports the feasibility of percutaneous vertebral augmentation in the treatment of several clinically relevant spinal instrumentation failure conditions, with excellent safety and efficacy profiles, both in avoidance of revision surgery and for pain palliation.

Metabolite findings in tumefactive demyelinating lesions utilizing short echo time proton magnetic resonance spectroscopy.

BACKGROUND AND PURPOSE: To use MR spectroscopy to aid in the diagnosis of demyelinating disease and to help differentiate tumefactive demyelinating lesions from neoplastic processes. MATERIALS AND METHODS: MR imaging of the brain was obtained in 4 patients who presented clinically with focal neurologic deficits. MR imaging initially revealed parenchymal mass lesions. Single-voxel MR spectroscopy was then performed utilizing a point-resolved spectroscopy sequence protocol with a short echo time (30 msec). RESULTS: MR imaging revealed a focal ring-enhancing mass in one patient, multiple ring-enhancing lesions in the second patient, a large area of edema and mass effect without associated enhancement in the third patient, and multiple solid and peripherally enhancing lesions in the fourth patient. MR spectroscopic results in all 4 patients demonstrated marked elevation of the glutamate and glutamine peaks (2.1-2.5 ppm). Other nonspecific (and in a sense confounding) findings included elevation of the choline peak (3.2 ppm), elevation of the lactate peak (1.3 ppm), elevation of the lipid peak (0.5-1.5 ppm), and decrease in the N-acetylaspartate peak (2.0 ppm). All 4 patients were eventually given the diagnosis of multiple sclerosis based on CSF analysis, brain biopsy, and/or clinical follow-up. CONCLUSION: MR spectroscopic metabolite information may be useful in the diagnosis of demyelinating disease by demonstrating elevation of the glutamate/glutamine peaks because elevation of these peaks is typically not seen in aggressive intra-axial neoplastic processes. This is particularly beneficial in the rarer cases of tumefactive demyelinating lesions, which are very difficult to differentiate from neoplasms by imaging findings alone.

Artifact simulating subarachnoid and intraventricular hemorrhage on single-shot, fast spin-echo fluid-attenuated inversion recovery images caused by head movement: A trap for the unwary.

BACKGROUND AND PURPOSE: Single-shot, fast spin-echo, fluid attenuated inversion recovery (SS-FSE-FLAIR) images are frequently used to detect disease in the brain and subarachnoid space in confused or uncooperative patients who may move during the examination. In some of these patients, high signal intensity areas are seen on good-quality images in the subarachnoid space and ventricular system in locations not associated with high CSF flow. These artifacts may simulate hemorrhage or leptomeningeal disease. The purpose of this article was to determine the cause of these artifacts, describe ways to recognize them, and find methods to reduce or eliminate them. METHODS: Healthy volunteers were studied on 6 occasions with conventional multisection FSE-FLAIR images and SS-FSE-FLAIR images while at rest and while nodding and rotating their heads at different speeds. In addition, SS-FSE-FLAIR images with different section widths of the initial inverting pulse and a non-section-selective initial inversion pulse were performed with the subjects moving their heads in the same way. The scans of 30 successive patients with acute neurologic syndromes who had been studied with SS-FSE-FLAIR sequences were reviewed for evidence of high signal intensity in the CSF in regions not associated with high CSF flow. RESULTS: Each of the volunteers showed areas of increased signal intensity in CSF at sites apart from those associated with rapid pulsatile CSF flow on SS-FSE-FLAIR images acquired during head motion. The images were otherwise virtually free of motion artifact. The use of a wider initial inversion pulse section and a non-section-selected initial inversion pulse reduced the extent of these artifacts. Nineteen of the 30 patients showed areas of high signal intensity in the CSF in regions not associated with highly pulsatile CSF flow. Six of these patients had negative lumbar punctures for blood and xanthochromia and normal CSF protein levels. CONCLUSION: High signal intensity artifacts may be seen in CSF as a result of head movement on otherwise artifact-free images when imaging uncooperative patients with SS-FSE-FLAIR sequences. These artifacts have a different mechanism and distribution from those caused by CSF pulsation and may simulate subarachnoid and intraventricular hemorrhage. Artifact recognition is aided by signs of patient motion during the examination. The artifacts can be reduced by use of increased section width and non-section-selective initial inversion pulses. Recognition of these artifacts is important, because the circumstances in which the SS-FSE-FLAIR sequence is used and the particular properties of the sequence may conspire to produce a trap for the unwary.