Osteoid osteoma of a cervical vertebral body.

An osteoid osteoma in the anterior part of the body of the fourth cervical vertebra occurred in a 22-year-old female. The patient's main complaint was neck pain and occasional numbness of the extremities. The pain was relieved by analgesics. Plain radiography and a 99Tcm MDP bone scan showed a non-specific abnormality. CT suggested the pathological diagnosis with reasonable certainty. The unusual location of the lesion and the role of various diagnostic modalities are discussed and the literature reviewed.

Thallium-201 retention in focal intracranial lesions for differential diagnosis of primary lymphoma and nonmalignant lesions in AIDS patients.

UNLABELLED: The purpose of this study was to determine whether 201Tl retention in focal intracranial lesions can help distinguish central nervous system (CNS) lymphoma from toxoplasmosis and other nonmalignant CNS lesions in patients with acquired immunodeficiency syndrome. METHODS: Forty-nine patients who presented with focal lesions on CT and/or MRI had 201Tl brain SPECT studies (early and delayed image sets) performed shortly after admission. Early and delayed 201Tl uptake ratios were obtained for the positive studies, and the retention index of thallium was calculated (delayed/early target-to-background mean count ratio). RESULTS: Twenty-nine patients had foci of significantly increased 201Tl uptake on the early images in regions of corresponding CT/MRI lesions. Ten of these patients had biopsy-proven lymphomas. Another patient was found to have metastatic adenocarcinoma. Twelve additional patients had a response to radiation therapy or a clinical course consistent with lymphoma and six patients had a false-positive SPECT study. The early uptake ratio could not separate malignant from nonmalignant lesions. The 201Tl retention index in patients with lymphomas (1.18 +/- 0.16) was significantly higher than the retention index in adenocarcinoma (0.24) and in the six nonmalignant lesions (0.62 +/- 0.07). The lowest retention index in patients with lymphoma was 1.07, and the highest retention index in nonmalignant lesions was 0.70. Twenty patients showed no 201Tl uptake in the regions of CT/MRI lesions. Three of them had biopsies consistent with a benign etiology, and one patient was diagnosed with tuberculosis. Fifteen patients improved clinically on antitoxoplasmosis medications alone, and one patient had CNS lymphoma. The overall sensitivity of 201Tl brain SPECT was 96%. The specificity was 76% by counting all studies with abnormal 201Tl uptake, but it increased to 100% when the retention index was also considered. CONCLUSION: The retention index increases the specificity of 201Tl brain SPECT in human immunodeficiency virus patients. In the presence of abnormal early 201Tl uptake, it is essential to perform delayed imaging and calculate the retention index to distinguish nonmalignant lesions from lymphoma. The absence of 201Tl uptake on early images at the site of a CT/MRI abnormality excludes the diagnosis of lymphoma with a high degree of confidence and delayed imaging is unnecessary.

Venous architecture of cerebral hemispheric white matter and comments on pathogenesis of medullary venous and other cerebral vascular malformations.

The parenchymal veins, especially the deep medullary veins, of the cerebral hemispheres were studied in detail by analyzing the stereoroentgenograms of multiple brain slices of postmortem injected brain specimens (injected into the internal carotid arteries in 17 cases and into the jugular veins in 12 cases). The presence of four zones--the first (or outer), the second (or candelabra), the third (or palmate) and the fourth (or subependymal) zone--of venous convergence was confirmed within the centrum semiovale, particularly in the frontoparietal area. Other venous convergences such as those related to the optic radiation in the para-atrial area were also found. Arterial branching zones were also observed in the areas similar to those of the medullary veins. It appears that these converging zones are created by rapidly growing crossing nerve fiber tracts, i.e., projection, commissural, and association fibers which grow rapidly during intrauterine and postnatal life. Pathogenesis of medullary venous malformation is also discussed from anatomical viewpoint, venoarchitecture of the pial, parenchymal, and subependymal veins and of the dural venous sinuses. The possibility of a similar mechanism (partial, mild, repetitive venoocclusive disease developing over a long period with fluctuating venous pressure) leading to formation of most (if not all) cases of medullary venous malformation and in some, if not many, cases of cerebral vascular malformations [aside from gene abnormality (chromosome 7) in familial cavernous angiomatosis, particularly in Hispanic American or other familial hereditary conditions] has been postulated.

The role of thallium-201 uptake and retention in intracranial tumors after radiotherapy.

UNLABELLED: This study prospectively assessed the diagnostic accuracy and prognostic value of 201TI uptake and retention in primary and metastatic intracranial tumors treated by conventional radiotherapy and/or radiosurgery. METHODS: An initial 201TI study (early and delayed images), was obtained in 60 postsurgical patients, 6-12 wk after radiotherapy or radiosurgery. Repeat imaging was performed as clinically warranted. Tumor-to-background count ratios and a retention index (RI) were calculated for all lesions. RESULTS: Abnormally increased 201TI uptake was observed in 40 of 60 patients. In all patients with positive results, the diagnosis of residual tumor was confirmed at biopsy or by clinical follow-up. In 20 of 60 patients, no abnormal 201TI uptake was observed, despite findings on CT and/or MRI scans that were suspicious for tumor. Ten of the negative 201TI studies were confirmed as true-negatives by the clinical course and by resolution of CT/MRI abnormalities. The remaining 10 negative SPECT studies ultimately proved to be false-negatives: six of these patients had lesions < 1 cm in maximum diameter, one patient had a large metastatic choriocarcinoma; and three patients had low-grade astrocytomas > 2 cm in minimum diameter. Tumor-to-background ratio of 201TI uptake did not distinguish between tumor type, or predict clinical outcome. The RI of 201TI was significantly higher for metastatic melanoma than for other tumor metastases. It demonstrated reasonably good correlation with clinical outcome: 6/7 patients with eventual tumor regression showed a decrease in RI on follow-up examination, and 4/5 patients with eventual tumor progression had an increase in RI. CONCLUSION: Thallium-201 brain SPECT appears to be a useful noninvasive imaging technique in patients irradiated for intracranial tumors. Thallium-201 scintigraphy has very high specificity (100% in this cohort) for detecting viable residual tumor. False-negative findings may occur. Quantitative analysis of 201TI uptake has limited diagnostic and prognostic significance, but changes in 201TI retention after radiation therapy seems to have prognostic value.

Pantopaque simulating thrombosed intracranial aneurysms on MRI.

A patient is presented in whom iophendylate (Pantopaque) within the basal cisterns closely resembled the appearance on MRI of thrombosed aneurysms of the middle cerebral arteries. The sometimes subtle differences between the appearances on MRI of Pantopaque and aneurysmal clot are discussed to permit accurate diagnosis without resorting to more invasive diagnostic tests, such as cerebral angiography.

Giant cell tumour of the seventh cervical vertebra.

A 43-year-old man presented with bubbly expansion and rarefaction of the body of the seventh cervical vertebra. The lesion involved the right side of the vertebral arch and had a soft-tissue component extending mainly anterior to the vertebra. Histopathologic examination of the specimen obtained by open biopsy revealed a giant cell tumour. Giant cell tumours of the spine, excluding the sacrum, are rare. Radiographically, they may be confused with metastatic carcinoma, plasmacytoma, lymphoma, chordoma and even benign lesions, particularly aneurysmal bone cyst and brown tumour of hyperparathyroidism. However, giant cell tumour occurs mainly in younger patients, involves the vertebral body selectively in most cases and has a bubbly appearance associated with rarefaction and expansion of the vertebral body, characteristics that may be helpful in the diagnosis.

The radiographic evaluation of sinonasal tumors: an overview.

It is axiomatic that advances in head and neck imaging improve our understanding of head and neck diseases. Dramatic improvements in radiologic imaging in recent years have, as a corollary, dramatically improved our understanding of sinonasal tumors. Older techniques such as plain film radiography and multidirectional tomography poorly delineate normal anatomy and pathologic changes in the craniofacial region. Modern imaging modalities depict sinonasal tumors and their metastases in detail, yielding information that allows treatment planning to proceed rationally. The radiologic examination is commonly employed as a precise "map" for implementation of therapy, and imaging studies are essential in the follow-up evaluation for tumor residual or recurrence. This article provides an overview of the current contributions made by head and neck radiology to the understanding and clinical management of sinonasal tumors.

The age at onset of Alzheimer's disease and an intracranial area measurement. A relationship.

OBJECTIVE: To examine the possibility that premorbid brain size may influence the age at onset of symptoms of Alzheimer's disease (AD). DESIGN: Retrospective case series. SETTING: Outpatients attending a memory disorders clinic in a tertiary referral center. PATIENTS: Twenty-eight female patients with the diagnosis of probable AD, selected for the availability of informant derived estimates of age at onset of symptoms and computed tomographic scans of the head satisfying angulation criteria. MAIN OUTCOME MEASURE: An average intracranial area of two adjacent computed tomographic scan sections appropriately angled was used as a correlate of premorbid brain size. Strict intracranial volume measurement was not performed. RESULTS: Age at onset of symptoms of AD correlated positively (r = .48, P = .009) with our measure of premorbid brain size. There was no confounding by education, height, or ethnicity. CONCLUSION: Premorbid brain size may be an important determinant of the age at onset of symptoms of AD. Epidemiologic studies of AD may need to assess the relationship between brain size and putative risk factors, eg, low educational attainment, since there is evidence that brain size is not distributed uniformly across populations.

Giant intracranial aneurysms with skull base erosion and extracranial masses: CT and MR findings.

OBJECTIVE: To present the CT and MR findings of three patients with giant intracranial aneurysms (GIAs), each of which eroded the skull base and had an extracranial mass component. A literature review of GIAs was also performed. MATERIALS AND METHODS: In the past year the imaging studies of three patients with these unusual GIAs were collected at our institutions. All three patients had had CT, and one patient had had MR on a 1.5 T GE unit. RESULTS: One patient had a 5 cm GIA in the left petrocavernous region, filling the middle cranial fossa and extending into the left sphenoid sinus and the left posterior ethmoid complex. The aneurysm had heterogeneous high attenuation and extensive rim calcification. The second patient had a 5 cm GIA that filled most of the left middle cranial fossa, eroding the floor and lateral wall and extending into the infratemporal fossa and parapharyngeal space. The aneurysm was partially thrombosed and had minimal rim calcification. The third patient had a 4 cm left cavernous GIA that eroded the floor of the middle cranial fossa and extended into the subjacent parapharyngeal space. The lesion was partially thrombosed and had an enhancing lumen. The rim had low signal intensity on MR. None of these patients had a history of trauma. CONCLUSION: Giant intracranial aneurysms can cause significant skull base erosion and extend into the paranasal sinuses, parapharyngeal space, and infratemporal fossa. The CT and MR findings can lead to an accurate diagnosis.

Spect brain imaging in neurologic disease.

In recent years cerebral SPECT imaging is rapidly evolving as a clinical tool in the evaluation of a variety of neurologic disorders. In large part, the major advances in brain imaging which have occurred in the last four years are related to new developments in instrumentation and radiopharmaceuticals. In particular, the increased availability of multidetector and dedicated ring detector systems has given rise to improved image resolution and more rapid patient throughput. Advances in the field of radiopharmaceutical development, particularly as it pertains to perfusion brain SPECT agents, has also contributed to the advances in the field. As a result of these developments, there has been an expanded interest in and use of brain SPECT imaging procedures in the evaluation of cerebrovascular disease, dementia, epilepsy, and head trauma.