Magnetic resonance diffusion weighted imaging in cerebral fat embolism.

The use of diffusion weighted imaging with apparent diffusion coefficient mapping in the diagnosis of cerebral fat embolism is shown here to demonstrate infarcts secondary to fat emboli more intensely than T2 weighted sequences 24 hours after the onset of symptoms. Embolic foci are hypointense on apparent diffusion coefficient mapping consistent with cytotoxic edema associated with cell death and restricted water diffusion. This technique increases the sensitivity for detecting cerebral fat embolism and offers a potentially important tool in its diagnosis.

How often are nonenhancing supratentorial gliomas malignant? A population study.

The presence of contrast enhancement in a brain tumor is often regarded as a sign of malignancy. The authors identified 314 patients with malignant and low-grade supratentorial glial neoplasms in an unselected population, 58 of which lacked contrast enhancement on preoperative neuroimaging. Nonenhancing gliomas were malignant in approximately one third of cases, especially in older patients. Histologic confirmation of the diagnosis is therefore important in all patients suspected of harboring a primary glial neoplasm.

Use of the Alberta Stroke Program Early CT Score (ASPECTS) for assessing CT scans in patients with acute stroke.

BACKGROUND AND PURPOSE: Clinicians are insecure reading CT scans by using the one-third rule for acute middle cerebral artery stroke (1/3 MCA rule) before treating patients with recombinant tissue plasminogen activator. The 1/3 MCA rule is a poorly defined volumetric estimate of the size of cerebral infarction of the MCA. A 10-point quantitative topographic CT scan score, the Alberta Stroke Program Early CT Score (ASPECTS), is described and illustrated. A sharp increase in dependence and death occurs with an ASPECTS of 7 or less. We describe how to use ASPECTS and why it works with CT scans obtained on all commonly used axial baselines. We also describe interobserver reliability among clinicians from different specialties and with different experience in reading CT scans in the context of acute stroke. METHODS: The six physicians who developed ASPECTS answered a questionnaire on precisely how they interpret and use ASPECTS. The ASPECTS areas as interpreted by these physicians were compared with one another and with standards in the literature. kappa statistics were used to assess the interobserver reliability of ASPECTS versus the 1/3 MCA rule. RESULTS: The exact methods of interpretation varied among the six individual observers, with either a 3:3 or 4:2 split on the specific questions. The overall interobserver agreement was good compared with that of the 1/3 MCA rule. Normal anatomic vascular and interobserver variations explain why ASPECTS can be applied with different CT axial baselines. CONCLUSION: ASPECTS is a systematic, robust, and practical method that can be applied to different axial baselines. Clinician agreement is superior to that of the 1/3 MCA rule.

Symptomatic hemorrhage after alteplase therapy not due to silent ischemia.

BACKGROUND: Stroke thrombolysis-related intracerebral hemorrhage may occur remotely from the anatomical site of ischemia. One postulated mechanism for this is simultaneous multiple embolization with hemorrhage into a "silent" area of ischemia. RESULTS: A patient suffered a disabling stroke affecting the right cerebral hemisphere. He was treated with intravenous alteplase and underwent extensive early imaging with multimodal MRI. Several hours after treatment he developed a brainstem hemorrhage despite having no evidence of ischemia on DWI MRI in the brainstem. CONCLUSION: Not all occurrences of remote ICH after stroke thrombolysis are secondary to multiple emboli with silent ischemia.

Idiopathic hypertrophic pachymeningitis: a report of two patients and review of the literature.

PURPOSE: We report the treatment and follow-up, including MRI, of two patients with idiopathic hypertrophic pachymeningitis and review the English language literature, with emphasis on management and outcome in this rare disorder. METHODS AND MATERIALS: The files of two patients were reviewed, with relevant histopathology and imaging (MRI). The first patient has been followed for sixteen years (the longest MRI-documented postoperative course reported for this condition) and the second for two years. The English language literature was reviewed, including a summary of all reported patients that have been followed with MRI or CT imaging. RESULTS: Despite extensive investigation, no underlying etiology was determined in either patient. Histopathological studies revealed a chronic inflammatory dural infiltrate in both patients, with granulomas in the first but not the second patient. The first patient underwent surgery twice and has remained stable for sixteen years, despite persistent neurologic deficits. The second patient was managed with dexamethasone after a surgical biopsy, and experienced complete resolution of all neurological deficits and abnormalities seen with MRI. CONCLUSIONS: Although prompt and extensive surgery has been recommended for this condition, the results from our second patient indicate that complete remission can be achieved in some patients with biopsy and steroid therapy. This also supports the view that autoimmune mechanisms underlie idiopathic hypertrophic pachymeningitis. The first patient illustrates that extensive laminectomies may be an effective therapeutic option but chronic discomfort may result. If extensive surgery must be performed, laminoplasty should be done because of the potential for reduced pain and improved long-term spinal stability.

Building a "brain attack" team to administer thrombolytic therapy for acute ischemic stroke.

Before tissue plasminogen activator (tPA) was licensed for use in Canada, in February 1999, the Calgary Regional Stroke Program spearheaded the development and organization of local resources to use thrombolytic therapy in patients who had experienced acute ischemic stroke. In 1996 special permission was obtained from the Calgary Regional Health Authority to use intravenously administered tPA for acute ischemic stroke, and ethical and scientific review boards approved the protocols. After 3 years our efforts have resulted in improved patient outcomes, shorter times from symptom onset to treatment and acceptable adverse event rates. Areas for continued improvement include the door-to-needle time and broader education of the public about the symptoms of acute ischemic stroke.

MR imaging of neoplasms of the lumbar spine.

MR imaging has evolved as the primary modality for imaging spinal neoplasms; however, neoplasms must be distinguished from unusual appearances of degenerative lesions. This article reviews MR imaging findings of a variety of neoplastic lesions of the lumbar spine. For example, extradural, metastatic tumors are the most common; nerve sheath tumors are the most common intradural extramedullary tumors; and ependymoma accounts for most of the tumors arising from the filum terminale.

Correlation of neurologic dysfunction with CT findings in early acute stroke.

OBJECTIVE: To determine the frequency of early computed tomographic (CT) findings of ischemia and their relationship to symptom duration and neurologic dysfunction within 3 hours of ischemic stroke. METHODS: The CT scans of 39 acute stroke patients were evaluated for signs of early ischemic change within 3 hours of symptom onset and without knowledge of the patient's neurologic deficit or results of a 24 hour follow-up post-thrombolysis CT. Early CT signs of acute ischemic change or thromboembolism were hypoattenuation of the insular ribbon, obscuration of the lentiform nucleus, cortical hypodensity/effacement, and hyperdense middle cerebral artery sign. RESULTS: Signs of acute ischemic change were seen on the baseline scan in 25/39 patients (64%). Hypoattenuation of the insular ribbon was seen in 11 patients, obscuration of the lentiform nucleus in 13, cortical hypodensity/effacement in 13, and hyperdense middle cerebral artery sign in 7. The prevalence of early ischemic signs was directly associated with increasing neurologic disability at the time of presentation. No clear relationship existed between symptom duration and the presence of CT signs. CONCLUSIONS: Evidence of cerebral ischemia is frequently seen on CT within 3 hours of symptom onset. The degree of neurologic disability correlates with CT signs of ischemia.

Symptomatic hamartoma of the spinal cord associated with neurofibromatosis type 1. Case report.

The authors present a case in which a symptomatic hamartoma was found in the spinal cord of a patient with neurofibromatosis type 1 (NF-1). This 52-year-old woman presented with painful urinary incontinence. Magnetic resonance (MR) imaging revealed an intramedullary lesion within the lower thoracic spinal cord and conus medullaris, which was surgically removed. Pathological investigation showed a hamartomatous lesion consisting of glial cells, ganglion cells, abundant disoriented axons, and thin-walled vessels. This case provides a pathological correlate to the hamartomatous lesions demonstrated on MR imaging in patients with NF-1 and illustrates that these benign lesions may become symptomatic and require neurosurgical intervention.

Prospective study of postoperative magnetic resonance imaging in patients with malignant gliomas.

PURPOSE: We studied the natural history of postoperative enhancement on magnetic resonance (MR) scans in patients with malignant glioma to determine the following: (1) when a postoperative MR scan most accurately shows residual enhancing tumor; and (2) whether repeated doses of the contrast agent gadopentetate dimeglumine (Gd-DTPA) were well tolerated. PATIENTS AND METHODS: Seventeen patients with malignant glioma underwent tumor resection; four (24%) had nonenhancing tumors preoperatively. Serial MR scans were performed on postoperative days 1, 3, 5, 7, 14, and 21 and were analyzed qualitatively and quantitatively. The evolution of enhancement and subacute hemorrhage were described and measured. A uniform schedule of postoperative dexamethasone administration was used in all but four patients (24%) (each required higher doses to maintain neurologic function). RESULTS: Nontumoral, marginal (i.e., postsurgical) enhancement, potentially mimicking residual tumor, developed in eight patients (53%), including tumors that were nonenhancing preoperatively, and was maximal from days 5 to 14. Tumor enhancement was optimally visualized on postoperative days 3 to 5. Nine of 10 patients (90%) with gross residual enhancing tumor showed an increase of enhancing tumor size during the study. Methemoglobin was detected at some time in all patients (100%) and was usually minor, but in six (35%) it interfered with residual tumor assessment. The 97 doses of Gd-DTPA, administered in 17 patients, were well tolerated. CONCLUSION: When accurate assessment of residual enhancing tumor is needed in patients with malignant glioma, an MR scan performed on postoperative days 3 to 5 should minimize the confounding effects of postsurgical enhancement and methemoglobin. The repeated administration of Gd-DTPA over several weeks is well tolerated.

Multifocal white matter lesions.

There is a long differential diagnosis for multifocal white matter lesions on MR. The most common causes are prominent Virchow-Robin spaces, white matter ischemic change, and multiple sclerosis, but many other causes have been reported. Most of these are related to vascular or other demyelinating etiologies, but infectious/inflammatory disease, trauma, and neoplastic and other unusual causes may also be responsible. Typical imaging features of the more common multifocal white matter disorders are outlined, and the rarer causes are discussed briefly. An approach to imaging differential diagnosis is given, with emphasis on the differences between white matter ischemic lesions and multiple sclerosis.

Aortic arch interruption associated with ruptured cerebral aneurysm.

The authors present a case of aortic arch interruption in an adult, an anomaly that was discovered coincidentally during angiography for ruptured cerebral aneurysm. The presentation in adulthood with rupture of the aneurysm and the successful surgical treatment of both abnormalities are unusual.

Spontaneous thrombosis of an unruptured anterior communicating artery aneurysm. An unusual cause of ischemic stroke.

BACKGROUND: Stroke caused by spontaneous thrombosis of an unruptured intracranial aneurysm is a rare event. CASE DESCRIPTION: A 66-year-old woman experienced a transient ischemic attack and cerebral infarctions due to spontaneous thrombosis of an unruptured anterior communicating artery aneurysm. Extension of thrombus into both anterior cerebral arteries and the left middle cerebral artery, resulting in ischemic infarction in all three vascular territories, was diagnosed by CT scanning, MRI, and cerebral angiography and confirmed at autopsy. CONCLUSIONS: This case illustrates a rare complication of an unruptured saccular aneurysm with neuroimaging and pathological correlation. Morphological and hemodynamic factors that may have precipitated aneurysm thrombosis are discussed with reference to experimental models.

Cervical spine tumors.

Magnetic resonance imaging is the central imaging modality for cervical spine neoplasms. The majority of extradural lesions are metastatic. Nerve sheath tumors are the most common intradural neoplasm, followed by meningioma. Intramedullary tumors are less common. This article reviews tumors according to this classification, with emphasis on clinical considerations and imaging techniques and findings.

Diffuse-variant tenosynovial giant cell tumor: a rare and aggressive lesion.

The diffuse-variant tenosynovial giant cell tumor is rare. Although it shares histologic features with the exclusively intra-articular pigmented villonodular synovitis and local tenosynovial giant cell tumor, its behavior differs dramatically, being locally very aggressive. We report a case of a diffuse-variant aggressive tenosynovial giant cell tumor that, although diploid by flow cytometry, demonstrated trisomy 7 and 5 as well as clonal rearrangements involving chromosomes 1, 3, and 15. These cytogenetic abnormalities may be markers for aggressive behavior and useful for directing treatment.