Hemorrhage rates and outcomes when using up to 100 mg intra-arterial t-PA for thrombolysis in acute ischemic stroke.

This work presents a unique single center experience with intra-arterial delivery of tissue plasminogen activator (t-PA) doses as high as 100mg for thrombolysis. Hemorrhage volumes, hemorrhage rates, clinical outcomes and radiographic outcomes were assessed. Prospectively collected angiographic, clinical and laboratory information on 67 consecutive patients with acute ischemic stroke involving either the m1 segment of the middle cerebral artery, the intracranial internal carotid artery or the basilar artery were retrospectively analyzed. Patients who received more than 50 mg t-PA were compared with those patients receiving 50 mg or less. Outcome measures included: symptomatic hemorrhage, significant hemorrhage volume (greater than 25 ml), hemorrhage rate, change in National Institutes of Health stroke scale score at 24 hours and at hospital discharge, modified Rankin score at 90 days, in-hospital deaths, death within 90 days, reperfusion rate, and infarct volume. Multivariate logistic regression analysis demonstrated that t-PA dose over 50 mg was associated with higher rates of hemorrhage and larger hemorrhages. Poor pial collateral formation, poor reperfusion (less than 50% of the territory involved), and platelet count below 200 K/µL influenced hemorrhage. Limiting t-PA dose to 100mg rather than 50mg improved documented reperfusion rates from 37% to 61%. Restricting intra-arterial t-PA administration to 100mg rather than 50mg, is associated with higher overall reperfusion rates and improves overall outcomes, however, the hemorrhage rate is also elevated. Poor pial collateral formation and platelet count less than 200 K/µL may be reasons to curtail the use of higher t-PA dose to reduce hemorrhage rate.

Cerebral cortical lesions in multiple sclerosis detected by MR imaging at 8 Tesla.

BACKGROUND AND PURPOSE: Conventional imaging of ex-vivo brain at 1.5T in multiple sclerosis (MS) detects only a small fraction of the gray matter cerebral cortical lesions that can be detected by pathology. Our purpose was to examine if imaging at 8T can detect plaques in cortical gray matter (CGM) not evident at 1.5T. METHODS: An ex-vivo brain obtained at autopsy from a patient with MS was formalin fixed and 1 cm coronal slices were examined using MR imaging at 8T. RESULTS: Numerous cerebral cortical lesions not evident at 1.5T were seen at 8T. Lesions were easily identified using gradient-echo and spin-echo (SE) as well as diffusion images. MR imaging at 8T identified many of the types of plaques previously evident only by pathology. The magnitude of the cortical involvement in this 1 patient was severe. Lesions in the gray matter readily visible by high-field MR imaging were sometimes barely visible by pathology. MR imaging at 8T often facilitated the detection of such plaques by pathology. CONCLUSION: This study establishes the utility of high-field imaging at 8T in the delineation of plaques in the cerebral CGM in MS.

Prevalence and rupture rate of cerebral aneurysms discovered during intra-arterial chemotherapy of brain tumors.

BACKGROUND: During the administration of intra-arterial (IA) chemotherapy for the treatment of brain tumors (BTs), angiography may demonstrate asymptomatic, incidental cerebral aneurysms. The prevalence and complication rate of incidental aneurysms in patients undergoing IA chemotherapy remains unknown. It remains unclear whether the presence of an aneurysm represents an increased risk or a contraindication to this form of treatment. METHODS: We performed a chart and angiography review of BT patients receiving IA chemotherapy over the previous 16 months. Seventy-eight patients were identified with primary (39) and metastatic (39) BTs. RESULTS: The cohort consisted of 40 men and 38 women, with a mean age of 47.8 years (range, 22-80 years). During initial angiography, 8 patients (10.3%) were identified with incidental cerebral aneurysms. The aneurysms were saccular and varied in size from 2-4 mm (mean, 3 mm). Seven of the 8 patients continued IA chemotherapy after detection of the aneurysm, for a total of 35 IA procedures. Of these 7 patients, 5 expired from nonaneurysmal complications (mean survival, 5.4 months; range, 2-10 months); 4 from the primary tumor, and one from an infected craniotomy site. Two patients continue to survive; one remains in treatment, and the other has completed 12 months of IA therapy. There were no aneurysmal complications during or after IA treatment in any of the BT patients. CONCLUSION: Incidental aneurysms may be more common in patients with BTs than the general population. In our patient population, there was no indication that an incidental aneurysm was reason to preclude or delay the use of IA chemotherapy.

Postoperative evaluation for disseminated medulloblastoma involving the spine: contrast-enhanced MR findings, CSF cytologic analysis, timing of disease occurrence, and patient outcomes.

BACKGROUND AND PURPOSE: Postoperative MR imaging is routinely performed for staging of medulloblastoma because of frequent tumor dissemination along CSF pathways. The goals of this study were to: 1) determine the timing of disease occurrence and contrast-enhanced MR imaging features of disseminated medulloblastoma involving the spine and their relationship to patient outcomes; and 2) compare the diagnostic accuracy of MR imaging findings with CSF cytologic analysis. METHODS: Medical records, pathologic reports, and unenhanced and contrast-enhanced postoperative MR images of the spine and head from 112 patients who had resection of medulloblastoma were retrospectively reviewed. MR images of the spine were evaluated for abnormal contrast enhancement in the meninges and vertebral bone marrow. MR images of the head were evaluated for recurrent or residual intracranial tumor. Imaging data were correlated with available CSF cytologic results and patient outcomes. RESULTS: Twelve patients (11%) had tumor within the spinal leptomeninges depicted on MR images at the time of diagnosis. Twenty-five patients (22%) had disseminated disease in the spine (leptomeninges, n = 22; vertebral marrow, n = 1; or both locations, n = 2) on MR images 2 months to 5.5 years (mean, 2 years) after initial surgery and earlier negative imaging examinations. Eleven other patients (10%) had recurrent intracranial medulloblastoma without spinal involvement seen with MR imaging. Spinal MR imaging had a sensitivity of 83% in the detection of disseminated tumor, whereas contemporaneous CSF cytologic analysis had a sensitivity of 60%. The sensitivity of CSF cytologic analysis increased to 78% with acquisition of multiple subsequent samples, although diagnosis would have been delayed by more than 6 months compared with diagnosis by spinal MR imaging in six patients. Spinal MR imaging was found to have greater overall diagnostic accuracy than CSF cytologic analysis in the early detection of disseminated tumor (P = .03). Spinal MR imaging confirmed disseminated tumor when contemporaneous CSF cytologic findings were negative in 13 patients, whereas the opposite situation occurred in only two patients. False-positive results for spinal MR imaging and CSF cytologic analysis occurred when these examinations were obtained earlier than 2 weeks after surgery. The 5-year survival probability for patients with spinal tumor was 0.24 +/- 0.08 versus 0.68 +/- 0.05 for the entire study group. CONCLUSION: Spinal MR imaging was found to have greater diagnostic accuracy than CSF cytologic analysis in the early detection of disseminated medulloblastoma. CSF cytologic analysis infrequently confirmed disseminated tumor when spinal MR imaging results were negative. Delaying spinal MR imaging and CSF cytologic analysis by more than 2 weeks after surgery can reduce false-positive results for both methods. The presence of disseminated medulloblastoma in the spine seen with MR imaging is associated with a poor prognosis.

High resolution MRI of the deep brain vascular anatomy at 8 Tesla: susceptibility-based enhancement of the venous structures.

PURPOSE: The purpose of this work was to describe the deep vascular anatomy of the human brain using high resolution MR gradient echo imaging at 8 T. METHOD: Gradient echo images were acquired from the human head using a transverse electromagnetic resonator operating in quadrature and tuned to 340 MHz. Typical acquisition parameters were as follows: matrix = 1,024 x 1,024, flip angle = 45 degrees, TR = 750 ms, TE = 17 ms, FOV = 20 cm, slice thickness = 2 mm. This resulted in an in-plane resolution of approximately 200 microm. Images were analyzed, and vascular structures were identified on the basis of location and course. RESULTS: High resolution ultra high field magnetic resonance imaging (UHFMRI) enabled the visualization of many small vessels deep within the brain. These vessels were typically detected as signal voids, and the majority represented veins. The prevalence of the venous vasculature was attributed largely to the magnetic susceptibility of deoxyhemoglobin. It was possible to identify venous structures expected to measure below 100 microm in size. Perforating venous drainage within the deep gray structures was identified along with their parent vessels. The course of arterial perforators was more difficult to follow and not as readily identified as their venous counterparts. CONCLUSION: The application of high resolution gradient echo methods in UHFMRI provides a unique detailed view of particularly the deep venous vasculature of the human brain.

High resolution MRI of the deep gray nuclei at 8 Tesla.

PURPOSE: High resolution MR images obtained from a normal human volunteer at 8 T are utilized to describe the appearance of iron-containing deep gray nuclei at this field strength. METHOD: High resolution (1,024 x 1,024 matrix) near-axial gradient echo images of the deep gray nuclei were acquired on a human volunteer by using an 8 T scanner. The images were acquired using a transverse electromagnetic resonator operating in quadrature. The following parameters were utilized: TR = 750 ms, TE = 17 ms, flip angle = 45 degrees, receiver bandwidth = 50 kHz, slice thickness = 2 mm, FOV = 20 cm. The 8 T images were reviewed and correlated to the known anatomy of the deep nuclei by comparing them with images observed at lower field strength, published diagrams, and histologic sections. In addition, the appearance of the nuclei was related to the known imaging characteristics of brain iron at lower fields. RESULTS: The caudate, globus pallidus, putamen, thalami, substantia nigra, and red nuclei were clearly identified. The structures with the highest levels of iron, the globus pallidus, substantia nigra, and red nuclei, demonstrated significantly decreased signal, providing a map of iron distribution in the human brain. CONCLUSION: Preliminary imaging at 8 T demonstrates the ability to acquire ultra high resolution images of the deep nuclei, with signal characteristics believed to represent the distribution of brain iron. This may prove to be important in the early diagnosis of several neurodegenerative disorders.

Human leptomeningeal and cortical vascular anatomy of the cerebral cortex at 8 Tesla.

PURPOSE: The purpose of this work was to describe the human leptomeningeal and cortical vascular anatomy as seen at high resolution on an 8 T UHFMRI system. METHOD: With a 1024 x 1024 matrix, axial gradient echo images of the cerebral cortex were acquired on a human volunteer at 8 T with TR 500 ms, TE 16 ms, flip angle 22.5 degrees, bandwidth 53 kHz, and slice thickness 2.84 mm. The same subject was evaluated at 1.5 T using similar parameters. The images were then reviewed in detail and compared with known cortical and leptomeningeal vascular anatomy. RESULTS: Two hundred forty micron in-plane resolution images of the human brain were acquired at 8 T without evident artifact from susceptibility distortions, RF penetration, or dielectric resonances. The CSF, gray matter, and white matter structures were well discerned. The microscopic leptomeningeal vascular anatomy was well visualized, and the course of small perforating cortical vessels could be followed from the cortical surface to the white matter junction. CONCLUSION: Initial 8 T images of the brain demonstrate detailed leptomeningeal and cortical vascular anatomy.

Brain arteriovenous malformations.

The diagnostic evaluation of a brain arteriovenous malformation requires a thorough understanding of the imaging features seen on CT, MR, and conventional angiography. Therapeutic planning requires a comprehensive understanding of the angioarchitecture of AVMs, necessitation selective and superselective angiography in order to give an accurate assessment of the lesion. This article will discuss the diagnostic work-up of AVMs. AVM treatment requires a multidisciplinary approach that includes interventional neuroradiology, radiosurgery, and neurosurgery. The considerations and philosophies of each discipline will discussed in order to provide the perspective required for the comprehensive treatment of AVMs.

Malignant hemangioendothelioma (angiosarcoma) of the skull: plain film, CT, and MR appearance.

Hemangioendothelioma is a rare neoplasm of bone that uncommonly involves the skull. We present a case of grade III malignant hemangioendothelioma (also known as angiosarcoma) of the skull in a 13-year-old boy and describe the plain film, CT, and MR appearance of this neoplasm as well as its histopathology.

Postcontrast meningeal MR enhancement secondary to intracranial hypotension caused by lumbar puncture.

Intracranial hypotension, which is most commonly caused by lumbar puncture, can lead to intense meningeal enhancement, which resolves on its own once the intracranial hypotension has been corrected. The characteristic clinical presentation of severe postural headaches with a low opening CSF pressure on subsequent lumbar puncture and a history of prior dural puncture should alert one to the diagnosis, thus avoiding an extensive workup for carcinomatosis or infection.

The calvarium.

The calvarium is a crucial structure that can manifest a great deal of pathology. The plain film remains the main imaging modality, although CT and MRI are becoming increasingly important. We discuss its anatomy, normal variants, congenital and developmental anomalies, hematologic disease, idiopathic disorders, neoplasms, metabolic disease, trauma, and the postoperative skull. Whenever possible, we emphasize CT and MRI.

Morphine-augmented cholescintigraphy with a false-negative result and an apparent ectopic gallbladder.

Morphine-augmented cholescintigraphy has been shown to be a highly sensitive and specific means of evaluating acute cholecystitis. False-negative results do occur infrequently, however, and such a case is reported. In addition, this case initially demonstrated an apparent ectopic gallbladder, and thus anomalies in location of the gallbladder will be discussed.

Indium-111 imaging of an inflammatory abdominal aortic aneurysm.

Indium-111-labeled leukocyte scanning has been shown to be a highly sensitive and specific imaging modality in the detection of abscess formation. Leukocyte infiltration occurs in a variety of inflammatory states as well as some noninflammatory states, leading to false-positive results. We report a case of an inflammatory abdominal aortic aneurysm imaged by 111In. It is not clear whether the activity noted is due to the inflammatory nature of the aneurysm or to hemorrhage present within the wall of the aneurysm.

Retroclival arachnoid cyst.

Retroclival arachnoid cyst is a rare mass lesion, with only seven cases previously reported in literature. MR is the imaging modality of choice in its evaluation and in its differentiation from epidermoid cyst. The case reported here was surgically proved and had an uncharacteristic MR signal intensity that was higher than that of cerebrospinal fluid due to previous hemorrhage.

Pulmonary varix: magnetic resonance findings.

The magnetic resonance appearance of a confluent-type pulmonary varix is correlated with computed tomography and angiographic findings. This case demonstrates the usefulness of magnetic resonance in the evaluation of cardiovascular lesions.