Cerebral perfusion in posterior reversible encephalopathy syndrome measured with arterial spin labeling MRI.

BACKGROUND AND PURPOSE: The pathophysiologic basis of posterior reversible encephalopathy syndrome (PRES) remains controversial. Hypertension (HTN)-induced autoregulatory failure with subsequent hyperperfusion is the leading hypothesis, whereas alternative theories suggest vasoconstriction-induced hypoperfusion as the underlying mechanism. Studies using contrast-based CT and MR perfusion imaging have yielded contradictory results supporting both ideas. This work represents one of the first applications of arterial spin labeling (ASL) to evaluate cerebral blood flow (CBF) changes in PRES. MATERIALS AND METHODS: After obtaining Institutional Review Board approval, MRI reports at our institution from 07/2015 to 09/2020 were retrospectively searched and reviewed for mention of "PRES" and "posterior reversible encephalopathy syndrome." Of the resulting 103 MRIs (performed on GE 1.5 Tesla or 3 Tesla scanners), 20 MRIs in 18 patients who met the inclusion criteria of clinical and imaging diagnosis of PRES and had diagnostic-quality pseudocontinuous ASL scans were included. Patients with a more likely alternative diagnosis, technically non-diagnostic ASL, or other intracranial abnormalities limiting assessment of underlying PRES features were excluded. Perfusion in FLAIR-affected brain regions was qualitatively assessed using ASL and characterized as hyperperfusion, normal, or hypoperfusion. Additional quantitative analysis was performed by measuring average gray matter CBF in abnormal versus normal brain regions. RESULTS: HTN was the most common PRES etiology (65%). ASL showed hyperperfusion in 13 cases and normal perfusion in 7 cases. A hypoperfusion pattern was not identified. Quantitative analysis of gray matter CBF among patients with visually apparent hyperperfusion showed statistically higher perfusion in affected versus normal appearing brain regions (median CBF 100.4 ml/100 g-min vs. 61.0 ml/ 100 g-min, p < 0.001). CONCLUSION: Elevated ASL CBF was seen in the majority (65%) of patients with PRES, favoring the autoregulatory failure hypothesis as a predominant mechanism. Our data support ASL as a practical way to assess and noninvasively monitor cerebral perfusion in PRES that could potentially alter management strategies.

Isolated lateral collateral ligament complex injury in rock climbing and Brazilian Jiu-jitsu.

We report two occurrences of high-grade tears of the lateral collateral ligament complex (LCLC), consisting of the anterolateral ligament (ALL) and fibular collateral ligament (FCL). One injury occurred in a rock climber and the other in a martial artist. Increasing awareness of isolated injuries of the LCLC will allow for appropriate diagnosis and management. We review and discuss the anatomy of the LCLC, the unique mechanism of isolated injury, as well as physical and imaging examination findings.

Radiation-induced cavernous malformations of the cauda equina mimicking carcinomatous or infectious meningitis. A case report.

The authors present a case of multiple radiation-induced cavernous malformations of the cauda equina in a patient with a remote history of testicular cancer and extended field radiation therapy. Magnetic resonance imaging (MRI) demonstrated multiple nodular areas of enhancement coating the nerve roots of the cauda equina, mimicking an aggressive leptomeningeal process such as carcinomatous or infectious meningitis. Biopsy of one of these lesions revealed ectatic vascular channels devoid of intervening neuroglial tissue consistent with cavernous malformation.

Multifocal intravascular papillary endothelial hyperplasia in the retroperitoneum and spine: a case report and review of the literature.

The authors present a unique case of intravascular papillary endothelial hyperplasia (IPEH) localized in the renal hilum, retroperitoneum, and spine in a patient with Wegener granulomatosis. IPEH rarely occurs in the abdomen or spine with few cases reported in the literature. No case has been reported of IPEH involving both the retroperitoneum and spine. In our case, MR imaging revealed enhancing masses in the right renal hilum and retroperitoneum as well as multiple focal enhancing lesions throughout the spine with lower thoracic ventral thecal sac compression. The diagnosis was established by resection of the renal hilum mass, and interval follow-up is deemed necessary for the remaining lesions because the long-term evolution of IPEH with conservative treatment alone is not well established.

Utilization of glutamate/creatine ratios for proton spectroscopic diagnosis of meningiomas.

INTRODUCTION: Our purpose was to determine the potential of metabolites other than alanine to diagnose intracranial meningiomas on proton magnetic resonance spectroscopy (MRS). METHODS: Using a 1.5-T MR system the lesions were initially identified on FLAIR, and T1- and T2-weighted images. Employing standard point-resolved spectroscopy (PRESS) for single voxel proton MRS (TR 1500 ms, TE 30 ms, 128 acquisitions, voxel size 2 x 2 x 2 cm, acquisition time 3.12 min), MR spectra were obtained from 5 patients with meningiomas, from 20 with other intracranial lesions, and from 4 normal controls. Peak heights of nine resonances, including lipid, lactate, alanine, NAA (N-acetylaspartate), beta/gamma-Glx (glutamate + glutamine), creatine, choline, myo-inositol, and alpha-Glx/glutathione, were measured in all spectra. The relative quantity of each metabolite was measured as the ratio of its peak height to the peak height of creatine. RESULTS: Relative quantities of alpha-Glx/glutathione, beta/gamma-Glx, and total Glx/glutathione were significantly elevated in meningiomas compared to the 20 other intracranial lesions and the normal control brains. Alanine was found in four of five meningiomas, but lactate partially masked the alanine in three meningiomas. None of the other lesions or control brains showed an alanine peak. The one meningioma with no alanine and the three others with lactate had elevated Glx. CONCLUSION: While alanine is a relatively unique marker for meningioma, our results support the hypothesis that the combination of glutamate/creatine ratios and alanine on proton MRS is more specific and reliable for the diagnosis of meningiomas than alanine alone.

Diffusion-weighted magnetic resonance imaging versus computed tomography in the diagnosis of acute ischemic stroke.

Current treatment protocols using reperfusion therapy for acute ischemic stroke rely on non-contrast computed tomography (NCCT), with most indications including the absence of acute hemorrhage or large volume of infarction in the presence of clinical signs and symptoms. This predictably results in a significant incidence of the administration of reperfusion therapy to patients with "stroke mimics," such as migraine headache or Todd's paralysis after a seizure. Diffusion-weighted imaging (DWI) is a technique based on magnetic resonance imaging (MRI) that may be more sensitive and specific for acute cerebral ischemia than NCCT. In addition, data for techniques such as perfusion-weighted imaging can be acquired with minimal additional time required. This may allow better risk assessment of a clinical response to reperfusion therapy vs. the possibility of hemorrhagic complications. This article describes a methodical review of studies comparing the sensitivity, specificity, positive predictive value, and negative predictive value of DWI vs. NCCT in the evaluation of acute ischemic stroke. Data from studies meeting our screening criteria are combined to produce overall values for each.

Diffusion-weighted imaging distinguishes recurrent epidermoid neoplasm from postoperative arachnoid cyst in the lumbosacral spine.

Diffusion-weighted imaging can be used to distinguish epidermoid tumor from arachnoid cyst in the intracranial compartment. We report the use of diffusion-weighted imaging in a postoperative spine to successfully distinguish a recurrent epidermoid tumor from arachnoid cyst in a noninvasive manner. Our case illustrates the value of this readily available sequence presently not generally used in the clinical evaluation of spinal pathology.

Proton magnetic resonance spectroscopy of mesial temporal sclerosis: Analysis of voxel shape and position to improve diagnostic accuracy.

OBJECTIVE: To determine if change in voxel shape and position improves the lateralization of magnetic resonance (MR) spectroscopy to the side of the MR imaging and/or electroencephalography (EEG) abnormality in mesial temporal sclerosis. METHODS: In 10 patients with unilateral mesial temporal sclerosis and 5 controls, MR spectroscopy was performed. Long echo time single-voxel spectroscopy was obtained in the right and left hippocampus. First, the standard 2-cm x 2-cm x 2-cm cubic voxels were placed bilaterally. Then, 1-cm x 2-cm x 4-cm rectangular voxels were used. With this rectangular voxel shape, more of the hippocampus and less of the adjacent medial temporal lobe were included in the interrogation voxel. N-acetylaspartate-to-creatine (NAA/Cr) ratios and choline-to-creatine (Cho/Cr) ratios were obtained. The difference between the affected and unaffected sides in the patients was calculated and compared with the controls. Additionally, the mean difference and standard deviation were determined. Predictive values and Student t tests were also performed. RESULTS: In all 10 patients, using the NAA/Cr ratios, the rectangular voxel correctly identified the abnormal side. The cubic voxel only identified the abnormal side in 6 of the 10 patients, however. Additionally, the mean difference between the affected and unaffected sides was 0.30 for the rectangular voxel but only 0.003 for the cubic voxel; that is, there was no overall significant difference when using the cubic voxel (P = 0.007). No significant correlation between the affected and unaffected sides was found using the Cho/Cr ratios. No significant difference between the right and left sides was found in the controls. CONCLUSION: Use of a 1-cm x 2-cm x 4-cm rectangular voxel places more of the hippocampus in the region of interrogation with less partial volume artifact from the adjacent brain parenchyma, which occurs with use of the standard 2-cm x 2-cm x 2-cm cubic voxel, resulting in improved correct lateralization of MR spectroscopy to the side of the MR imaging and/or EEG abnormality.

Treatment of ischemic stroke complicating cardiac catheterization with systemic thrombolytic therapy.

Ischemic stroke is a rare but serious complication of cardiac catheterization. We report a case in which systemic thrombolytic therapy was successfully utilized in treating a patient with a cerebellar stroke, leading to obtundation during elective cardiac catheterization. Underlying bilateral vertebrobasilar disease with thrombotic embolization to the basilar artery was postulated to be the pathophysiological basis for the stroke and subsequent success of thrombolytic treatment in this patient. As the consequences of this rare complication are severe, systemic thrombolytic therapy should be considered for patients suffering an acute ischemic stroke during cardiac catheterization or percutaneous coronary intervention.

Stereolithographic vascular replicas from CT scans: choosing treatment strategies, teaching, and research from live patient scan data.

Our goal was to develop a system that would allow us to recreate live patient arterial pathology by using an industrial technique known as stereolithography (or rapid prototyping). In industry, drawings rendered into dicom files can be exported to a computer programmed to drive various industrial tools. Those tools then make a 3D structure shown by the original drawings. We manipulated CT scan dicom files to drive a stereolithography machine and were able to make replicas of the vascular diseases of three patients.

Aneurysmal pressure changes with nondetachable balloon placement and fluid infusion: rationale for liquid embolization.

BACKGROUND AND PURPOSE: To improve the safety and efficacy of liquid embolization, we evaluated changes in pressures in experimental aneurysms. METHODS: We created three replicas of a lateral sidewall aneurysm and placed them in a physiologic flow circuit. A 3 x 10-mm nondetachable balloon was positioned in the parent vessel across the aneurysmal neck. Intra-aneurysmal pressures were measured at baseline and after balloon inflation. Fluid was infused into the sac via a 1.45F microcatheter during inflation, and maximal pressures were noted. Measurements were repeated eight times in each aneurysm. RESULTS: After balloon inflation, average intra-aneurysmal pressures increased: 12 mm Hg (13%, sigma(n - 1) = 0.46) for aneurysm 1 (baseline mean arterial pressure [MAP], 94 mm Hg), 15 mm Hg (58%, sigma(n - 1) = 0.88) for aneurysm 2 (baseline MAP, 26 mm Hg), and 15 mm Hg (58%, sigma(n - 1) = 0.92) for aneurysm 3 (baseline MAP, 26 mm Hg). During inflation and infusion, pressures increased slightly: 1.1 (0.94%, sigma(n - 1) = 0.64), 1.6 (3.9%, sigma(n - 1) = 1.1), and 1.9 (4.6%, sigma(n - 1) = 1.2) mm Hg for aneurysms 1, 2, and 3, respectively. Despite complete balloon occlusion of the distal aneurysmal neck, a channel between the proximal aneurysmal neck and the parent-vessel lumen persisted along the microcatheter. Fluid exited the sac via this channel, preventing a concomitant, significant increase in pressure during infusion. CONCLUSION: Intra-aneurysmal pressure modestly increased with inflation of a parent-vessel balloon across the neck. When liquid was infused into the sac during inflation, further increases were minimal.

Intracranial meningeal disease: comparison of contrast-enhanced MR imaging with fluid-attenuated inversion recovery and fat-suppressed T1-weighted sequences.

BACKGROUND AND PURPOSE: Contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging has been reported to have higher sensitivity for detecting leptomeningeal disease compared with contrast-enhanced T1-weighted MR imaging. The purpose of this study was to compare contrast-enhanced T1-weighted MR images with fat suppression to contrast-enhanced FLAIR images to determine which sequence was superior for depicting meningeal disease. METHODS: We reviewed MR images of 24 patients (35 studies) with a variety of meningeal diseases. The MR imaging protocol included contrast-enhanced T1-weighted MR images with fat suppression (FS) and contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images that were reviewed by three neuroradiologists and were assigned a rating of positive, equivocal, or negative for abnormal meningeal enhancement. The two sequences were compared side by side to determine which better depicted meningeal disease. RESULTS: Abnormal meningeal enhancement was positive in 35 contrast-enhanced T1-weighted MR images with FS and in 33 contrast-enhanced FLAIR studies. In the first group, which had the T1-weighted sequence acquired first (21 of 33 studies), contrast-enhanced T1-weighted images with FS showed superior contrast enhancement in 11 studies (52%), inferior contrast enhancement in six studies (29%), and equal contrast enhancement in four studies (19%) compared with the contrast-enhanced FLAIR images. In the second group, which had the FLAIR sequence acquired first (12 of 33), contrast-enhanced T1-weighted images with FS showed superior contrast enhancement in seven studies (58%), inferior contrast enhancement in two studies (17%), and equal contrast enhancement in three studies (25%). CONCLUSION: Contrast-enhanced T1-weighted MR imaging with FS is superior to contrast-enhanced FLAIR imaging in most cases for depicting intracranial meningeal diseases.

Lymphocytic vasculitis mimicking aggressive multifocal cerebral neoplasm: mr imaging and MR spectroscopic appearance.

We present a case of multifocal enhancing lesions confined to the right cerebral hemisphere that mimicked diffuse neoplasm. MR spectroscopy revealed not only minimal elevation of the choline peak, but also marked elevation of the glutamate and glutamine peaks, findings that are more suggestive of an inflammatory process. Biopsy showed lymphocytic vasculitis, a rare variant of primary angiitis of the CNS. Following appropriate medical therapy, MR imaging demonstrated complete resolution of the lesions.

Role of proton magnetic resonance spectroscopy in the diagnosis of gliomatosis cerebri: a unique pattern of normal choline but elevated Myo-inositol metabolite levels.

A patient with histologically proven gliomatosis cerebri presented with a normal choline level but a markedly abnormal elevated myo-inositol level on magnetic resonance (MR) spectroscopy. We describe the case presentation, imaging findings (in particular, the unique MR spectroscopic pattern), and their significance regarding the diagnosis of this relatively rare neoplasm.

Intramedullary spinal cord metastasis of lung adenocarcinoma presenting as Brown-Sequard syndrome.

BACKGROUND: It is extremely rare for cancer to present first as an intramedullary spinal cord metastasis. Furthermore, because it is unlikely for spinal cord neoplasm to present acutely, an acute presentation may signify metastatic disease and should be considered in the initial differential diagnosis. METHODS: The authors present a case of a 59-year-old man presenting with Brown-Sequard syndrome and in whom metastatic lung adenocarcinoma to the spinal cord was subsequently discovered. Review of the literature reveals this case to be one of only a very few where intramedullary tumor was the first manifestation of metastatic disease. RESULTS: The mainstay of treatment for intramedullary spinal metastases remains steroids, radiation, and chemotherapy, though no well-designed study compares these modalities by long-term survival and functional results. This patient underwent local radiation and systemic chemotherapy following surgical resection. CONCLUSIONS: This patient had no preoperative signs suggesting disease in other organs, making the diagnosis of lung adenocarcinoma metastatic to the intramedullary cord surprising, especially given the extremely rare incidence of spinal intramedullary metastatic disease. However, the patient had an acute presentation, uncommon for primary neoplasm, which may be an indication of metastatic disease.

Aneurysm flow dynamics: alterations of slipstream flow for neuroendovascular treatment with liquid embolic agents.

BACKGROUND AND PURPOSE: The main issue with use of a liquid embolic agent is one of safety. To determine and improve the efficacy of potential neuroendovascular treatment regimens, particularly the use of liquid embolic agents, we evaluated the changes in aneurysm flow dynamics resulting from alterations of parent vessel flow. METHODS: We created silicone replicas of a laboratory-created aneurysm model and a basilar artery aneurysm cast from a human cadaver. Replicas were placed in a circuit of pulsatile non-Newtonian fluid, and flows were adjusted to simulate human physiologic flow velocity, profile, and volume. Individual fluid slipstreams were opacified with isobaric dyes. Images were obtained of the unaltered vascular replica; after placement of a nondetachable balloon in the parent vessel at multiple locations proximal to, across, and distal to the aneurysm neck; and after placement of a stent across the aneurysm neck. Aneurysms were then occluded with a cyanoacrylate liquid embolic agent in association with each device. RESULTS: In the unaltered replica, flow entered the distal aneurysm neck and impacted against the distal lateral aneurysm wall. Disturbed, but nonturbulent, flow then continued along the aneurysm wall in a vortex pattern and exited at the proximal aspect of the aneurysm neck. With the balloon partially inflated in the parent vessel, the slipstream velocity increased. This resulted in more rapid flow in the aneurysm sac, a less favorable condition for deposition of liquid embolic material. The effect was more pronounced with greater degrees of balloon inflation (resulting in greater parent vessel narrowing) and when the balloon was proximal to the aneurysm neck compared with more distal parent vessel positioning. Only with complete occlusion of the parent vessel lumen, either proximal to, across, or distal to the aneurysm sac, was there intraaneurysmal flow reduction (ie, stasis), a more favorable condition for liquid embolic material deposition. Also, with the balloon positioned across the aneurysm neck, not only did the liquid agent remain in the aneurysm sac, but also the surface could be molded to re-create a normal parent vessel lumen. A stent placed across the aneurysm neck caused the slipstreams to lose their coherence as they passed through the stent mesh. This prevented slipstream impact against the aneurysm sidewall and decreased the intraaneurysmal fluid velocity. During deposition of liquid embolic agent through the stent sidewall into the aneurysm sac, the stent mesh appeared to provide a barrier to passage of the embolic agent into the adjacent parent vessel, also a more favorable condition for liquid embolic material deposition. CONCLUSION: Knowledge of aneurysm flow dynamics and the changes incurred after endovascular parent vessel flow alteration provides a basis for safer aneurysm obliteration by using a liquid embolic agent with a neurointerventional technique.

Intramedullary spinal cord astrolipoma: case report.

OBJECTIVE AND IMPORTANCE: Reported is a case of a thoracic intramedullary astrocytoma with a lipomatous component, a so-called astrolipoma. This is the only known case of a single intraspinal astrolipoma in an otherwise healthy patient. CLINICAL PRESENTATION: The patient was a 36-year-old woman with dorsal thoracic pain of more than 1 month's duration, mild lower extremity weakness, and incomplete sensory loss to the T10 level. INTERVENTION: Magnetic resonance imaging of the thoracolumbar spine revealed a fusiform mass at the T9-T11 level. The patient underwent T9-T11 laminectomies and complete resection of the tumor. In the initial postoperative period, the patient's symptoms worsened. However, 3 months after surgery, the patient was clinically improved and was able to walk without assistance. Twelve months after surgery, imaging revealed no evidence of tumor. CONCLUSION: The current treatment plan and recommendation, assuming this tumor will behave like a low-grade glioma or lipoma, is continued radiographic surveillance after gross total resection. Reresection is recommended for tumor recurrence or significant regrowth. The long-term prognosis for astrolipoma is unknown.

Transient focal leptomeningeal enhancement in Sturge-Weber syndrome.

The authors describe a 36-year-old man with Sturge-Weber syndrome who presented with focal seizures and subsequently developed a temporary post-ictal hemianopia. Magnetic resonance imaging of the brain demonstrated focal leptomeningeal enhancement, which subsequently resolved.

Epidural blood patch in a patient with an arachnoid cyst.

Arachnoid cysts are relatively common occurrences, with the majority being asymptomatic. The safety of an epidural blood patch in a patient with an arachnoid cyst has not been reported. Our patient had a known thoracic arachnoid cyst and required epidural blood patch for a postdural puncture headache. Magnetic resonance imaging obtained following the epidural blood patch demonstrated no alterations of the cyst or spinal cord compression.

Reproducibility analysis of a new objective method for measuring arteriovenous malformation nidus size at angiography.

BACKGROUND AND PURPOSE: Currently, no specific method exists to measure arteriovenous malformation (AVM) nidus size, a requirement in assessing the success of treatment. Additionally, the commonly used evaluation provides only a linear one-dimensional measurement of this three-dimensional entity. The purpose of this study was to devise an improved method for measuring AVM nidus size, an irregularly shaped radiologic entity, that provides objective and reproducible results. METHODS: The procedure involved digitizing angiograms obtained before and after treatment, making the gray scale uniform, printing images on standard bond paper, delineating the nidus area, measuring the nidus area with a polar planimeter, and finally, correcting for geometric magnification. Three observers made the measurements. The corrected nidus areas were tabulated, and the mean, standard deviation, interobserver variability, and confidence intervals (CIs) were calculated. RESULTS: On both anteroposterior and lateral views, the Kendall coefficient of concordance (a measure of interobserver variability) was equal to 0.97, signifying excellent agreement. Additionally, these values were within the 95% CIs; this result showed that they were unlikely the result of chance. CONCLUSION: Precise measurements of an AVM nidus are required to properly analyze changes in the lesion after endovascular embolization (ie, to evaluate treatment success). Because of the irregular contours of an AVM nidus, measuring an area with planimetry, rather than with the usual linear dimensions, should yield more exact results.