Localization of spinal dural arteriovenous fistulas from the spatial relationships of perimedullary vessels on standard MRI

OBJECTIVE

The goal in this study was to explore the spatial relationship of perimedullary vessels visualized on MRI to localize the side and the site of spinal dural arteriovenous fistula (SDAVF).

METHODS

A retrospective analysis of 30 consecutive patients diagnosed with SDAVF on MRI was undertaken. Two experienced reviewers blinded to all reports and angiographic images analyzed T2-weighted as well as postcontrast T1-weighted sequences. A focal prominent zone of perimedullary vessels with lateralization to one side in the thecal space was evaluated to locate the side and the site of the fistula. Spinal digital subtraction angiography served as the gold standard technique.

RESULTS

Good interrater agreement (κ = 0.77) was shown for the diagnosis of SDAVF with perimedullary vessels on T2-weighted MRI. Flow voids on T2-weighted MRI demonstrated a sensitivity of 1.0 (95% CI 1.0-1.0) and an accuracy of 0.87 (95% CI 0.79-0.95) to identify the presence of fistula. The flow voids on T2-weighted MRI also demonstrated 0.88 (95% CI 0.71-1.03) sensitivity and 0.81 (95% CI 0.70-0.92) accuracy to identify the side of SDAVF. Furthermore, flow voids on T2-weighted MRI showed 0.87 (95% CI 0.71-1.03) sensitivity and 0.87 (95% CI 0.79-0.95) accuracy to identify the site of SDAVF within 3 vertebral levels above or below the actual site. Area under the receiver operating characteristic curve demonstrated significant results (0.87 [95% CI 0.73-1.0]; p < 0.001) for flow voids on T2-weighted MRI to identify the site of shunts within 3 vertebral levels in the cranial or caudal direction.

CONCLUSIONS

Spatial distribution of perimedullary vessels observed on standard MRI show promise to locate the side and the site of fistula in patients with SDAVF.

Temporal radiographic and histological study of necrosis development in a mouse glioblastoma model

Tumor necrosis is a poor prognostic marker in glioblastoma (GBM) and a variety of other solid cancers. Accumulating evidence supports that necrosis could facilitate tumor progression and resistance to therapeutics. GBM necrosis is typically first detected by magnetic resonance imaging (MRI), after prominent necrosis has already formed. Therefore, radiological appearances of early necrosis formation and the temporal-spatial development of necrosis alongside tumor progression remain poorly understood. This knowledge gap leads to a lack of reliable radiographic diagnostic/prognostic markers in early GBM progression to detect necrosis. Recently, we reported an orthotopic xenograft GBM murine model driven by hyperactivation of the Hippo pathway transcriptional coactivator with PDZ-binding motif (TAZ) which recapitulates the extent of GBM necrosis seen among patients. In this study, we utilized this model to perform a temporal radiographic and histological study of necrosis development. We observed tumor tissue actively undergoing necrosis first appears more brightly enhancing in the early stages of progression in comparison to the rest of the tumor tissue. Later stages of tumor progression lead to loss of enhancement and unenhancing signals in the necrotic central portion of tumors on T1-weighted post-contrast MRI. This central unenhancing portion coincides with the radiographic and clinical definition of necrosis among GBM patients. Moreover, as necrosis evolves, two relatively more contrast-enhancing rims are observed in relationship to the solid enhancing tumor surrounding the central necrosis in the later stages. The outer more prominently enhancing rim at the tumor border probably represents the infiltrating tumor edge, and the inner enhancing rim at the peri-necrotic region may represent locally infiltrating immune cells. The associated inflammation at the peri-necrotic region was further confirmed by immunohistochemical study of the temporal development of tumor necrosis. Neutrophils appear to be the predominant immune cell population in this region as necrosis evolves. This study shows central, brightly enhancing areas associated with inflammation in the tumor microenvironment may represent an early indication of necrosis development in GBM.

A Quantitative Subarachnoid Hemorrhage Grading System, Including Supratentorial and Infratentorial Cisterns, With Multiplanar Computed Tomography Reformations

Background

Subarachnoid hemorrhage (SAH) grading scales typically evaluate a limited number of cisterns on the axial plane. The goal of our study is to apply a simple quantitative yet comprehensive SAH grading scale to all major intracranial cisterns, including the infratentorial cisterns, with multiplanar computed tomography (CT) reformations.

Methodology

We performed a retrospective review of 94 consecutive cases of spontaneous SAH presenting within 72 hours of onset. SAH was categorized into five grades based on the short-axis thickness of SAH in 20 intracranial cisterns measured on the axial, coronal, and sagittal planes. Statistical analysis was performed for inter-rater agreement with kappa statistics, for inter-plane agreement by Spearman correlation statistics, and for inter-rater and inter-plane agreement by Pearson correlation statistics.

Results

The extended kappa coefficient for the three reviewers across all 20 cisterns varied from 0.38 (0.27, 0.50) to 0.59 (0.52, 0.65) on the axial plane. The kappa coefficient for two reviewers varied from 0.46 (0.33, 0.59) to 0.70 (0.60, 0.80) on the coronal plane and from 0.35 (0.20, 0.49) to 0.87 (0.77, 0.96) on the sagittal plane. The average grade of cisterns per case demonstrated mostly excellent correlation between the imaging planes with Spearman correlation statistics (≥0.70). Pairwise concordance correlation coefficient of the total SAH score revealed agreement ranging from 0.81 to 0.90 in all three planes. Pearson correlation statistics of the average total SAH scores revealed excellent correlation among the three planes (≥0.91).

Conclusion

A simple quantitative SAH grading scale can be successfully applied to the supratentorial and infratentorial cisterns in three standard CT imaging planes.

Role of Neurovascular Compression of Oculomotor Nerve in Ophthalmoplegic Migraine

Ophthalmoplegic migraine is considered to occur more commonly in children than in adults. It commonly affects the oculomotor nerve among the cranial nerves. Demyelination of the nerve is proposed as the main mechanism for the etiology of ophthalmoplegic migraine, though it is not fully understood. Neurovascular compression as a cause of ophthalmoplegic migraine has not been well demonstrated in children. In this report, we present a case of a 13-year-old male with recurrent episodes of left ophthalmoplegic migraine. Oculomotor nerve enhancement with swelling was evident on MRI at the exit zone. Magnetic resonance angiography (MRA) revealed a sharp loop of the left posterior cerebral artery compressing the nerve. The case highlighted the unusual etiology of neurovascular compression resulting in ophthalmoplegic migraine in a pediatric patient. A supplemental case of ophthalmoplegic migraine in a seven-year-old male is also shown to highlight the role of neurovascular compression and the importance of using MR angiography to evaluate cases presenting clinically with ophthalmoplegic migraine.

Magnetic Resonance Angiography after Flow Diversion: The use of complementary MRA techniques to monitor aneurysm occlusion as well as device and arterial branch patency after flow diverter placement

BACKGROUND

Few studies have been performed to evaluate flow diversion with MRA. They have shown better success for MRA to assess the aneurysm response but limited success for the stent patency. Further, the patency of arterial branches on MRA remains to be explored.

METHODS

31 consecutive cases of carotid aneurysms treated with flow diversion were retrospectively evaluated with noncontrast time of flight (TOF), contrast enhanced TOF (CTOF) and cine MRA (TWIST) independently by two investigators for aneurysm occlusion, stent patency and arterial branch patency. DSA served as the gold standard technique.

RESULTS

There were 6 males and 25 females in the age range of years (mean ±SD). Stent patency, aneurysm occlusion and branch patency, mostly revealed substantial to perfect interobserver agreement (k >0.60). The sensitivity, specificity, positive and negative predictive values for the stent patency on source images of TOF were 0.99,0.84, 0.42 and 0.99 and on CTOF were 0.99, 0.89, 0.50 and 0.99 respectively.Sensitivity for the aneurysm response on the three MRAs ranged from 0.88 to 0.93,specificity from 0.64 to 0.75, positive predictive value from 0.69 to 0.79 and negative predictive value from 0.86 to 0.90. Sensitivity for the arterial branch patency among the three MRAs, ranged from 0.55 to 0.93, specificity from 0.61 to 0.68, positive predictive value from 0.79 to 0.93 and negative predictive value from 0.22 to 0.90.

CONCLUSIONS

Aneurysm occlusion, stent patency and arterial branch patency in flow diversion can be successfully evaluated with the combination of three MRA techniques.

Multiplanar CT evaluation of aneurysm rupture signs in subarachnoid hemorrhage

PURPOSE

In subarachnoid hemorrhage, noncontrast CT features are used to guide the localization of ruptured aneurysms on CT angiography and DSA. Multiplanar CT may improve the localization of aneurysm rupture sites over axial plane CT alone.

METHODS

Multiplanar CT in three orthogonal planes was used to evaluate 94 cases of SAH. Two investigators independently evaluated each imaging plane for focal thick SAH with mass effect, intracerebral hemorrhage, focal edema, filling defect, subdural hemorrhage, and dominant intraventricular hemorrhage. Also, rupture site was qualitatively identified by combining these variables in each plane and combination of three planes. DSA served as the gold standard to locate the rupture sites.

RESULTS

Interobserver agreement was k 0.60 to 0.79 for axial, k 0.43 to 0.86 for coronal and k 0.43 to 0.74 for sagittal planes. Good to substantial agreement was observed for the localization of rupture site in three planes (focal SAH with mass effect - k 0.78 to 0.85; filling defect - k 0.95 to 1.0; intracerebral hemorrhage - k 1.0; focal edema k 1.0; subdural hemorrhage - k 0.61 to 0.83). Dominant intraventricular hemorrhage revealed significant association with DSA to locate ruptured aneurysms (Fisher's exact test - Pr <  = P (< 0.001)). With non-missing data, frequency of correct ratings to locate rupture site was 66/67 (99%) in axial plane, 59/66 (89%) in coronal plane, 64/67 (96%) in sagittal plane and 77/77 (100%) in combined 3 planes.

CONCLUSIONS

Multiplanar CT head is more successful than axial plane CT alone for the localization of aneurysm rupture sites in SAH.

Neuroradiologic timing of intracranial hemorrhage in abusive head trauma

Determining the timing of intracranial injuries in general, and abusive head trauma (AHT) in particular, is important to the care of children with traumatic brain injury. Additionally, identifying the time of the injury provides important information as to who might have, and who did not, inflict the trauma. Understanding the appearance and evolution of intracranial findings on neuroimaging has been an important factor in assessing the time of the injury. However, a number of studies in the last two decades have both suggested greater uncertainty about the reliability of this process and advanced our knowledge in this area. In this review, the authors consider the biophysical factors that contribute to the appearance and evolution of intracranial hemorrhage and, in particular, subdural hemorrhage (SDH). The traditional view of SDH is predicated largely on prior studies of intracerebral hemorrhage, although a number of variables make this comparison untenable. Moreover, more recent studies have suggested a number of factors that could alter the density (CT) or signal intensity (MRI) and produce mixed density/intensity SDH. These factors need to be considered in interpreting neuroimaging studies. A number of these recent studies evaluating serial neuroimaging in children with AHT have modified our understanding of intracranial hemorrhage and its evolution in this context. Taken together, the studies to date, having important limitations, provide only broad ranges over which to time injuries. The authors conclude that neuroimaging studies at this time are not likely, in isolation, to be able to accurately pinpoint a specific time of injury; rather, neuroimaging can only provide a range of possible times and should instead be used as a means to supplement or corroborate timing based on clinical presentation and other imaging findings.

TAMI-23. NEUTROPHIL-TRIGGERED FERROPTOSIS PROMOTES TUMOR NECROSIS IN GLIOBLASTOMA PROGRESSION

Tumor necrosis indicates poor prognoses in many cancers, including glioblastomas (GBMs). Although thought to result from chronic ischemia, the underlying nature and mechanisms driving the involved cell death remain obscured by lack of animal models recapitulating the extent of necrosis in human GBMs. The molecular and clinical heterogeneity of GBMs adds further complexity. Not all GBMs contain necrosis. Mesenchymal (MES)-GBM, the subtype correlated with worst prognosis and highest treatment resistance, is most closely associated with necrosis. MES-GBM exhibits hyperactivity of transcriptional coactivator with PDZ-binding motif (TAZ), a Hippo tumor suppressive pathway effector whose expression in human GBMs predicts short survival. To elucidate mechanisms driving GBM necrosis, we devised a novel orthotopic mouse model recapitulating human MES-GBM phenotypically and histopathologically by expressing a constitutively-active TAZ mutant (TAZ4SA) in three human GBM cell lines (LN229, U87, and LN18) lacking MES signatures (GBM4SA). GBM4SA mice lived significantly shorter than mice implanted with GBMvector or mutant TAZ unable to bind its downstream effector, TEAD (GBM4SA-S51A). Extensive (≥30% of tumor volume) necrosis was present in GBM4SA mice but not GBMvector or GBM4SA-S51A. In GBM4SA tumors, neutrophils coincide with necrosis temporally and spatially. Neutrophil depletion dampens necrosis. Neutrophils isolated from mouse tumors killed co-cultured tumor cells. Neutrophils induce iron-dependent accumulation of lipid hydroperoxides within tumor cells by transferring myeloperoxidase-containing granules into tumor cells. Inhibiting myeloperoxidase suppresses neutrophil-induced tumor cytotoxicity. Intratumoral glutathione peroxidase 4 (GPX4) overexpression or acyl-CoA synthetase 4 (ACSL4) depletion diminishes necrosis and aggressiveness of tumors. Human GBM analysis indicates neutrophils and ferroptosis are associated with necrosis and predict poor survival. Together, we propose that certain tumor damage(s) during early tumor progression (i.e. ischemia) recruits neutrophils to damaged tissue and results in a positive feedback loop, amplifying GBM necrosis development. We show GBM necrosis involves neutrophil-triggered ferroptosis and reveal an unprecedented pro-tumorigenic role of ferroptosis.

Dilated Epidural Venous Plexus Causing Radiculopathy: A Report of 2 Cases and Review of the Literature

BACKGROUND

A dilated epidural venous plexus (DEVP) is a rare cause of radiculopathy, back pain, cauda equina syndrome, and other neurological symptoms. This vascular mass can be secondary to inferior vena cava obstruction, portal hypertension, vascular agenesis, and hypercoagulable states. Although rare, DEVP should be considered in the differential diagnosis for patients who present with lumbar radiculopathy.

CASE DESCRIPTION

We present 2 cases involving patients with lumbar DEVP as well as a literature review of the role of hypercoagulability, vascular anatomy, and inferior vena cava thrombosis in the development of DEVP. The first patient had a history of recurrent deep vein thrombosis, systemic lupus erythematosus, and antiphospholipid syndrome. The diagnosis of DEVP was determined after intraoperative biopsy. The patient reported symptom resolution at her 6-month postoperative appointment. The second patient developed DEVP associated with Klippel-Trenaunay syndrome. She presented with back pain and leg weakness, and DEVP was diagnosed via magnetic resonance imaging. A neurosurgeon is currently following the patient. We believe this is the first case of Klippel-Trenaunay syndrome associated with DEVP.

CONCLUSIONS

If a patient presents with an enhancing epidural lesion on magnetic resonance imaging and neurological symptoms, DEVP should be considered in the differential diagnosis. Additionally, a search for inferior vena cava thrombosis should be performed as well as risk factors for venous hypertension and hypercoagulable states.

CMET-14. BRAIN METASTASES: A NEW PATHOPHYSIOLOGY, A NEW TREATMENT PARADIGM, AND, PERHAPS, A NEW PROGNOSIS

INTRODUCTION

Brain metastases are widely held to reach the CNS through the blood stream. We provide evidence that the initial site of most CNS metastases is the CSF, with subsequent invasion of brain parenchyma. We also model the therapeutic implications of this novel hypothesis.

METHODS

Two neuro-radiologists independently assessed whether brain metastases were contiguous with CSF spaces in 200 consecutive patients using pre-treatment MRI. CSF was examined for malignant cells in 66 newly diagnosed, previously untreated patients. We contoured normal brain MRIs of 3 patients to calculate the percentage of brain within 5 mm of a CSF space. We queried an international neoplastic meningitis database to document response of brain metastases to intra-CSF chemotherapy.

RESULTS

Mean age was 64.2. One hundred patients were male; 143 had lung cancer, 15 melanoma, 12 gastrointestinal, 11 breast, 9 renal, 7 bladder. Mean number of metastases was 4.63. Eighty-five percent of metastases touched a CSF space. In 67% of patients, all metastases touched a CSF space. Neither histology, number or size of metastases, nor patient age predicted contiguity with CSF spaces. In our consecutive subset of patients, 44% (10/23) with one, 46% (5/11) with two, 63% (5/8) with three, and 71% (17/24) with >3 metastases had malignant cells in the CSF (R2=0.93, p=0.037). Five of 7 patients with both brain and CSF metastases receiving only IT chemotherapy experienced a substantial reduction in the size of at least some metastases. Up to 75% of the brain parenchyma lies within 5 mm of CSF spaces.

CONCLUSIONS

Our data suggest that brain metastases may access the CNS through the CSF rather than the bloodstream. IT chemotherapy may treat brain metastases. We suggest that the CSF should be monitored in all patients with, or at risk for, brain metastases. True cures may require treatment of the CSF space.

Susceptibility-weighted imaging of retinal hemorrhages in abusive head trauma

BACKGROUND

Retinal hemorrhages are one of the most important supportive evidences for abusive head trauma (AHT). Susceptibility-weighted imaging (SWI) is highly suited to identify various forms of intracranial hemorrhage in AHT. However its utility in imaging retinal hemorrhage is not well established.

OBJECTIVE

SWI is a sensitive sequence for identifying retinal hemorrhage on MRI.

MATERIALS AND METHODS

In this retrospective analysis, 26 consecutive infants and young children with a suspected admission diagnosis of AHT underwent indirect ophthalmoscopy and brain MRI protocol for AHT along with SWI. Brain susceptibility-weighted images of 14 age-matched children were used as controls. For detecting retinal hemorrhage, susceptibility-weighted images of patients and controls were reviewed randomly and independently by two neuroradiologists who were blinded to the history and ophthalmology findings. A pediatric ophthalmologist graded the indirect ophthalmoscopy images.

RESULTS

A diagnosis of AHT was confirmed in all 26 cases from a multidisciplinary meeting. Indirect ophthalmoscopy images were available in 21 cases. Ophthalmoscopy was positive for retinal hemorrhage in the right eye in 18 cases (85.7%) and in the left eye in 16 cases (76.2%). On SWI, retinal hemorrhage was identified in the right eye in 9/21 cases (42.8%) and in the left eye in 8/21 cases (38.1%) of AHT. Analysis of SWI in 21 cases of AHT demonstrated a sensitivity of 50%, specificity of 100%, positive predictive value of 100% and negative predictive value of 32% for detecting retinal hemorrhage.

CONCLUSION

SWI is moderately sensitive and highly specific for identifying retinal hemorrhage in AHT. Further studies are needed to identify steps to improve the efficiency of SWI in detecting retinal hemorrhage.

Pericallosal Lipoma and Cortical Dysplasia Masquerading as a Glioma

Intracranial lipomas represent approximately 1% of intracranial lesions generally felt to represent the abnormal persistence of the meninx primitiva and are commonly accompanied by various developmental brain abnormalities. We report a case of midline intracranial lipoma and evolving frontal lobe fluid-attenuated inversion recovery (FLAIR) abnormality concerning for glial neoplasm in a patient with intractable epilepsy. Our case shows evolving magnetic resonance imaging (MRI) features over two decades raising suspicion for low-grade neoplasm which was ultimately found to represent cortical dysplasia.

Neuroleukemiosis: Two Case Reports

Extramedullary tumors composed of myeloblasts or monoblasts can present in various locations. Patients with a history of acute myeloid leukemia (AML) can present with neuropathic pain and no evidence of relapse of their leukemia. Neuroleukemiosis is a form of extramedullary tumor present in the peripheral nervous systems (PNS) of leukemia patients. We report two AML patients who were in remission and later presented with neurological symptoms due to neuroleukemiosis with negative bone marrow biopsies.

A Comparison of Magnetic Resonance Angiography Techniques for the Evaluation of Intracranial Aneurysms Treated With Stent-assisted Coil Embolization

AIM

To identify the effective magnetic resonance angiography (MRA) technique to monitor intracranial aneurysms treated with stent-assisted coiling.

MATERIALS AND METHODS

Retrospective analysis of various MRA techniques was performed in 42 patients. Three neuroradiologists independently compared non-contrast time of flight (ncTOF) MRA of the head, contrast-enhanced time of flight (cTOF) MRA of the head and dynamic contrast-enhanced MRA (CEMRA) of the head and neck or of the head. Digital subtraction angiography (DSA) was available for comparison in 32 cases. Inter-rater agreement (kappa statistic) was assessed.

RESULTS

Artifactual in-stent severe stenosis or flow gap was identified by ncTOF MRA in 23 of 42 cases (55%) and by cTOF MRA in 23 of 38 cases (60%). DSA excluded in-stent stenosis or occlusion in all 32 cases. No difference was noted between ncTOF and cTOF in the demonstration of neck remnants or residual aneurysms in three cases each. CEMRA of the head and neck or of the head was rated superior to ncTOF and cTOF MRA by all three investigators in seven out of eight cases. In one case, all three techniques demonstrated signifcant artifacts due to double stent placement during coiling. The kappa statistic revealed 0.8 agreement between investigators.

CONCLUSIONS

In the assessment of stent-assisted coiling of intracranial aneurysm, both ncTOF and cTOF MRA show similar results. CEMRA tends to show better flow signals in stent and residual aneurysm.

‘Eiffel-by-Night’: A New MR Sign Demonstrating Reactivation in Idiopathic Hypertrophic Pachymeningitis

A forty- seven-year-old man presented with chronic headache with lower cranial nerve palsies of ten year duration with recent aggravation of symptoms. MRI revealed hypointensity — predominantly of the posterior falx cerebri and the tentorium cerebelli — on all sequences with intense peripheral contrast enhancement on CE SE T1, which on coronal images mimicked the illuminated Eiffel tower by night.

Venous injury in abusive head trauma

BACKGROUND

Abusive head trauma (AHT) is an important cause of serious brain injury in infants and young children who have characteristic clinical and imaging findings that are discordant with the clinical history provided. Recent attention has focused on abnormalities of the cranial venous sinuses and cortical veins, both on MRI and at autopsy. Although many have interpreted these to be secondary to the AHT, some have recently argued that these venous abnormalities represent primary cortical sinus and venous thrombosis that leads secondarily to subdural hemorrhage and secondary brain injury. Direct trauma to the veins and sinuses has been reported at autopsy in AHT, but there has been no systematic study of venous abnormalities in cases of AHT.

OBJECTIVE

The purpose of this study was to define the incidence and characteristics of venous and sinus abnormalities in AHT.

MATERIALS AND METHODS

We included all children <36 months of age who were diagnosed with abusive head trauma between 2001 and 2012 and who had MRI and magnetic resonance (MR) venography as part of their diagnostic workup. We analyzed age, gender and clinical findings. MRI and MR venography were analyzed independently by two neuroradiologists with a focus on abnormalities involving the intracranial veins and venous sinuses.

RESULTS

A total of 45 children were included. The median age was 3 months (range 15 days to 31 months) and 28 were boys (62%). Clinical findings included retinal hemorrhage in 71% and extracranial fractures in 55%. CT or MRI demonstrated subdural hemorrhage in 41 (91%); none had subdural effusions. In 31 cases (69%) MR venography demonstrated mass effect on the venous sinuses or cortical draining veins, with either displacement or partial or complete effacement of the venous structures from an adjacent subdural hematoma or brain swelling. We also describe the lollipop sign, which represents direct trauma to the cortical bridging veins and was present in 20/45 (44%) children.

CONCLUSION

Evidence of displacement or compression of cortical veins and sinuses from subdural hemorrhage or edema on MR venography was present in the majority of children with abusive head trauma. Evidence of direct trauma to the veins (lollipop sign) was identified in nearly half of cases. It is important to understand the superimposed effects of subdural hematoma and brain swelling on the veins and sinuses to differentiate it from cortical sinus and venous thrombosis.

Diffuse Subarachnoid Hemorrhage Secondary to Cerebral Venous Sinus Thrombosis

BACKGROUND

Aneurysmal rupture accounts for the majority of nontraumatic subarachnoid hemorrhage (SAH). Increasingly recognized is the occurrence of nontraumatic convexity SAH unaccounted for by aneurysmal rupture.

CASE REPORT

These presentations require consideration of rare but clinically significant sources of SAH. We report a patient presenting with prolonged mild headaches and acute onset of seizure like activity found to have diffuse subarachnoid hemorrhage and extensive dural venous sinus thrombosis involving the superior sagittal sinus and right transverse-sigmoid sinuses.

CONCLUSIONS

There are few reported cases of SAH secondary to dural sinus thrombosis; however most of these are convexity hemorrhage. Sinus thrombosis presenting as diffuse SAH is extremely rare, as is showcased in this report.

Sensitivity of 3D Gradient Recalled Echo Susceptibility-Weighted Imaging Technique Compared to Computed Tomography Angiography for Detection of Middle Cerebral Artery Thrombus in Acute Stroke

We aimed at comparing the sensitivity of magnetic resonance (MR) susceptibility-weighted imaging (SWI) with computed tomography angiography (CTA) in the detection of middle cerebral artery (MCA) thrombus in acute stroke. Seventy-nine patients with acute MCA stroke was selected using our search engine software; only the ones showing restricted diffusion in the MCA territory on diffusion-weighted images were included. We finally selected 35 patients who had done both MRI (including SWI) and CTA. Twenty random subjects with completely normal MRI (including SWI) exam were selected as control. Two neuroradiologists (blinded to the presence or absence of stroke) reviewed the SW images and then compared the findings with CT angiogram (in patients with stroke). The number of MCA segments showing thrombus in each patient was tabulated to estimate the thrombus burden. Thrombus was detected on SWI in one or more MCA segments in 30 out of 35 patients, on the first review. Of the 30, SWI showed thrombus in more than one MCA segments in 7 patients. CTA depicted branch occlusion in 31 cases. Thrombus was seen on both SWI and CTA in 28 patients. Thrombus was noted in two patients on SWI only, with no corresponding abnormality seen on CTA. Two patients with acute MCA showed no vascular occlusion or thrombus on either CTA or SWI. Only two case of false-positive thrombus was reported in normal control subjects. Susceptibility-weighted images had sensitivity and specificity of 86% and 90% respectively, with positive predictive value 94%. Sensitivity was 86% for SWI, compared with 89% for CTA, and this difference was statistically insignificant (P>0.05). Of all the positive cases on CTA (31) corresponding thrombus was seen on SWI in 90% of subjects (28 of 31). Susceptibility-weighted imaging has high sensitivity for detection of thrombus in acute MCA stroke. Moreover, SWI is a powerful technique for estimation of thrombus burden, which can be challenging on CTA.

Susceptibility weighted imaging: a new tool in magnetic resonance imaging of stroke

Susceptibility weighted imaging (SWI) is a magnetic resonance (MR) technique that is exquisitely sensitive to paramagnetic substances, such as deoxygenated blood, blood products, iron, and calcium. This sequence allows detection of haemorrhage as early as 6h and can reliably detect acute intracerebral parenchymal, as well as subarachnoid haemorrhage. It detects early haemorrhagic transformation within an infarct and provides insight into the cerebral haemodynamics following stroke. It helps in the diagnosis of cerebral venous thrombosis. It also has applications in the work-up of stroke patients. The sequence helps in detecting microbleeds in various conditions, such as vasculitis, cerebral autosomal dominant arteriopathy, subacute infarcts and leucoencephalopathy (CADASIL), amyloid angiopathy, and Binswanger's disease. The sequence also aids in the diagnosis of vascular malformations and perinatal cerebrovascular injuries. This review briefly illustrates the utility of this MR technique in various aspects of stroke diagnosis and management.

Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma

BACKGROUND AND PURPOSE

Vestibular schwannomas (VS) may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas. Demonstration of microhemorrhages in VS on T2*-weighted gradient-echo (GRE) sequences may have potential value to differentiate VS from CPA meningiomas.

MATERIALS AND METHODS

In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. Histopathologic examination was performed after surgery. Intratumoral hemosiderin was confirmed by pigment staining.

RESULTS

There were 15 patients in the VS group with 16 VS and 5 in the meningioma group with 5 posterior fossa meningiomas. Fourteen of the 16 VS and all 5 meningiomas were treated surgically and were confirmed on histopathologic examination. T2*-weighted GRE identified microhemorrhages on T2*-weighted sequence in 15 (93.75%) of the 16 VS. CT excluded calcification in all VS. T2-weighted turbo spin-echo (TSE) and fluid-attenuated inversion recovery (FLAIR) images recognized microhemorrhages in 2 cases. Pigment staining confirmed hemosiderin in all 14 surgically treated VS, and none of the meningiomas showed microhemorrhages on MR imaging. For the detection of microhemorrhages, T2*-weighted GRE showed a sensitivity of 93.8%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 83.3%. The sensitivity of T2 TSE and FLAIR for microhemorrhage was 12.5%. The Fisher exact test showed a statistically significant difference in the differentiation of VS from meningioma on the basis of detection of microhemorrhages (P < .01).

CONCLUSION

Most VS demonstrate microhemorrhages on T2*-weighted GRE. This finding is useful to differentiate VS from CPA meningiomas. T2*-weighted GRE should be used as a basic sequence to evaluate CPA tumors. Identification of microhemorrhages may have the potential to assess the aggressive biologic behavior of VS.

Clinical applications of susceptibility weighted MR imaging of the brain - a pictorial review

INTRODUCTION

Susceptibility-weighted imaging (SWI) is a novel magnetic resonance (MR) technique that exploits the magnetic susceptibility differences of various tissues, such as blood, iron and calcification. This pictorial review covers many clinical conditions illustrating its usefulness.

METHODS

SWI consists of using both magnitude and phase images from a high-resolution, three-dimensional fully velocity-compensated gradient echo sequence. Phase mask is created from the MR phase images, and multiplying these with the magnitude images increase the conspicuity of the smaller veins and other sources of susceptibility effects, which is depicted using minimal intensity projection (minIP).

RESULTS

The phase images are useful in differentiating between diamagnetic and paramagnetic susceptibility effects of calcium and blood, respectively. This unique MR sequence will help in detecting occult low flow vascular lesions, calcification and cerebral microbleed in various pathologic conditions and aids in characterizing tumors and degenerative diseases of the brain. This sequence also can be used to visualize normal brain structures with conspicuity.

CONCLUSION

Susceptibility-weighted imaging is useful in differentiating and characterizing diverse brain pathologies.

Moyamoya Disease with Cerebral Arteriovenous Malformation Presenting as Primary Subarachnoid Hemorrhage

The authors report a rare combination of definite moyamoya disease and brain arteriovenous malformation (AVM) presenting with primary subarachnoid hemorrhage (SAH) unheard of in the literature. The authors review the radiographic findings of this unique case with a brief review of literature.

Spurious absence of signal on 3D time-of-flight MR angiograms on 1 and 3 tesla magnets in cerebral arteries associated with a giant ophthalmic segment aneurysm: the need for alternative techniques

There are many high-resolution MR angiographic techniques available today for the evaluation of circle of Willis. We report a case of bilateral aneurysms of the carotico-ophthalmic segment, the left one being a giant aneurysm, in a 41-year-old woman. She underwent different MRA sequences on both 1 and 3Tesla magnets and a digital subtraction angiography. 3D time-of-flight angiograms can give spurious information on giant aneurysms and other techniques like phase contrast and dynamic contrast enhanced angiographies can supplement if not replace it. High field strength improves the objective quality of MR angiograms, but in the case of large aneurysms, intra aneurysmal and distal vessel signal loss can be a significant problem.