Location of the central sulcus via cortical thickness of the precentral and postcentral gyri on MR

PURPOSE

To determine whether relative cortical thickness measurements of the precentral and postcentral gyri can be used to differentiate the central sulcus from adjacent cortical sulci.

METHODS

Turbo inversion-recovery MR imaging of the entire brain was done with scans parallel to the anterior commissure-posterior commissure line. Cortical thickness was measured in each hemisphere with a jeweler's eyepiece with 0.1-mm gradations. Three measurements were obtained perpendicular to the central, precentral, and superior frontal sulci, as determined by means of established anatomic methods. The ratios of cortical thickness on both sides of the central, precentral, and superior frontal sulci were calculated and compared.

RESULTS

The mean ratio of precentral/postcentral gyri was 1.64 for the right hemisphere and 1.53 for the left hemisphere. The mean cortical thickness ratios were as follows: 1.01 for the right hemisphere and 3.01 for the left hemisphere across the precentral sulcus, and 1.03 for the right hemisphere and 0.99 for the left hemisphere across the superior frontal sulcus.

CONCLUSION

Cortical thickness measurements across the central sulcus provide a method for locating the primary motor (precentral gyri) and primary somatosensory (postcentral gyri) cortices. The higher mean cortical thickness ratio across the central sulcus corresponds with known cytoarchitectonic relationships.

Radiation-induced changes in the central nervous system and head and neck

Radiation therapy of the brain, neck, and spine can be associated with radiation-induced changes that are increasingly evident radiologically. These changes affect the central nervous system (focal necrosis, diffuse white matter injury, atrophy, mineralizing microangiopathy, telangiectasia, optic neuropathy, large vessel vasculopathy), bone (fatty replacement of marrow, osteoradionecrosis, sinus inflammation), and superficial and deep soft tissues and include neoplasia. Focal necrosis, which most commonly occurs at the treatment site, is seen at computed tomography (CT) and magnetic resonance (MR) imaging as a ring-enhancing mass with edema and mass effect, findings similar to those of tumor recurrence. Diffuse white matter injury appears as hypoattenuating (at CT) or hyperintense (at MR imaging) small foci near the frontal or occipital horns or as a confluent band extending from the ventricles to the corticomedullary junction. Fatty replacement of marrow is the most common osseous complication seen on MR images. Osteoradionecrosis, which occurs most often in the mandible, appears as a focal lytic area at CT and with abnormal marrow signal and cortical destruction at MR imaging. The most common changes in the superficial soft tissues of the head and neck, edema and fibrosis, are seen radiologically as skin thickening and increased soft-tissue attenuation with stranding of subcutaneous fat. Meningioma, the most common radiation-induced CNS tumor, can be distinguished from spontaneous meningiomas on the basis of clinical characteristics (eg, presence of focal alopecia and scalp atrophy).

Osteochondroma of the thoracic spine: an unusual cause of spinal cord compression

A 24-year-old man with hereditary multiple exostoses had numbness of the lower extremities and difficulty walking. CT displayed a calcified extradural mass lesion within the spinal canal at T-8 causing cord compression. MR imaging showed it to be contiguous with the upper endplate of T-8, suggesting the diagnosis of osteochondroma, a rare cause of cord compression, and distinguishing the lesion from a calcified disk fragment.

Spontaneous hemorrhage from a cerebral venous malformation related to thrombosis of the central draining vein: demonstration with angiography and serial MR

A cerebral venous malformation ruptured after acute thrombosis of its central draining venous channel, leading to intracerebral hemorrhage. The CT, MR, and angiographic studies unequivocally demonstrated subsequent progressive recanalization of the malformation, providing proof that venous malformations can spontaneously bleed and that venous thrombosis may be associated with, and perhaps produce, the hemorrhage.

High-resolution CT of mastoid sinus pneumocele with external auditory canal stenosis

A 34-year-old man presented with tinnitus and conductive hearing loss. CT demonstrated an expansile, air-containing cavity contiguous with mastoid air cells, narrowing the external auditory canal. This is a case of symptomatic pneumocele resulting in an air collection beneath external canal lining, possibly related to an abnormality in mastoid fusion.

Computed tomography and myelography in the evaluation of cervical degenerative disease

Computed tomography and myelography have long been used for diagnosing the effects of degenerative diseases of the cervical spine. Despite the continuous improvement of magnetic resonance scanning for this purpose, computed tomography techniques may provide an excellent screen for disc herniation and spinal stenosis. Computed tomography myelography is still considered by some workers to be the gold standard for demonstrating the soft tissue and bony changes that result in nerve root and spinal cord compression syndromes.

Interventional neuroradiologic treatment of head and neck lesions

Treatment of diseases involving the head and neck is most challenging because of the high density of vital structures in this region, the need to preserve function, and aesthetic requirements. Technical advances in needles, catheters, guide wires, and embolic materials have broadened the scope of interventional neuroradiologic procedures. Endovascular therapy can serve as a valuable adjunct to conventional surgical treatment for head and neck masses. In addition, it is now the treatment of choice for a variety of vascular lesions, such as arteriovenous malformations, arteriovenous fistulas, and pseudoaneurysms. In this article, examples from the spectrum of applications of endovascular therapy in the head and neck region are presented along with a discussion of therapeutic considerations.

Combined Arterial and Venous Approaches for Cure of Carotid-Cavernous Sinus Fistula in a Patient with Fibromuscular Dysplasia

We report the case of a woman with bilateral carotid artery fibromuscular dysplasia. The case illustrates some of the difficulties encountered in the treatment of carotid-cavernous fistula. For example, a previous contralateral carotid closure caused complications because carotid sacrifice was not now possible. This resulted in several embolization procedures requiring prolonged x-ray exposures. We show that transvascular embolotherapy must incorporate a flexible approach for access, selection of embolic materials, and clinical care.

Ocular ischemic syndrome during carotid balloon occlusion testing

The use of a double-lumen balloon catheter for temporary occlusion testing of the internal carotid artery permits simultaneous perfusion of the distal internal carotid artery (and ophthalmic artery) with heparinized saline. If saline is infused too rapidly, the result may be total or partial replacement of oxygenated blood within the ophthalmic artery. This replacement may produce the signs and symptoms of ocular ischemic syndrome. These include ipsilateral orbital pain and progressive uniocular visual loss. Simple technical adjustments in the performance of the occlusion test can prevent the development of this syndrome. Failure to recognize the cause of the observed visual loss may produce the false impression of a positive occlusion test or may falsely suggest that a thromboembolic complication has occurred. Awareness of the occurrence of this syndrome should prevent confusion concerning the predictive result of provocative carotid occlusion testing.

Granulocytic sarcoma is associated with the 8;21 translocation in acute myeloid leukemia

PURPOSE

Since the only three cases of granulocytic sarcoma among patients with acute myeloid leukemia (AML) seen at our institution during the last 12 years were each associated with the 8;21 translocation [t(8;21)], we sought to determine if this association is specific and more frequent than previously recognized.

PATIENTS AND METHODS

We report three patients with AML and t(8;21) who developed granulocytic sarcomas, and review the world literature.

RESULTS

Between 1980 and 1992, 53 cases of AML French-American-British (FAB) M2 were identified at our institution. Eight (15%) patients had t(8;21). Three of these eight patients (38%) developed granulocytic sarcoma. All three of our patients received conventional intensive antileukemic chemotherapy yet had short relapse-free survival durations. Several series of patients with t(8;21) report that granulocytic sarcomas occur in approximately 18% of this population, which is four times the expected incidence in AML. Thirty-seven cases have been previously reported. Although karyotype analyses were not reported in many cases of granulocytic sarcoma in the literature, the vast majority of abnormal karyotypes in patients with AML involved t(8;21). Recent work with a cell line derived from a patient with t(8;21) indicates that such cells are unusually adherent to culture bottles and are aggregable

CONCLUSION

Our data suggest that this association is more common than generally recognized and may be specific. Patients with t(8;21) should be observed closely for signs and symptoms of granulocytic sarcoma. These patients may have a less favorable prognosis than other patients with t(8;21). Cooperative oncology groups should retrospectively identify patients with AML and t(8;21) who had a poor outcome to determine if they had a disproportionate incidence of granulocytic sarcoma. If so, aggressive therapy such as bone marrow transplantation may be warranted early in the therapeutic strategy.

MR imaging of posterior fossa infarctions: vascular territories and clinical correlates

Ischemic infarctions in certain vascular territories of the cerebellum and brain stem can produce some characteristic radiologic and clinical patterns. The cerebellum serves as a coordination center for the maintenance of equilibrium and muscle tone and refines the movements of the somatic muscles. The anatomy of the brain stem is extremely complex, and small infarcts can potentially be disastrous. MR imaging depicts the anatomy of the posterior fossa and infarcts in this region with greater accuracy than was previously possible. Familiarity with the vascular territories and patterns of infarction of the posterior fossa depicted with MR imaging and familiarity with the associated clinical symptoms of stroke in this region can help the radiologist recognize these infarcts and correlate clinical and radiologic findings. When patients are referred for MR imaging of the brain because of clinical findings suggestive of infarction, it may be useful to obtain coronal or sagittal views in addition to axial images to better depict the vascular distribution of a suspected ischemic lesion.

Embolization of a life-threatening mandibular vascular malformation by direct percutaneous transmandibular puncture

Vascular malformations of the mandible are uncommon, but often present with significant hemorrhage. Transarterial vessel occlusion has become a valuable primary or adjunctive treatment for such lesions, as well as for most other symptomatic congenital and acquired head and neck vascular anomalies. Permanent embolic obliteration of the malformation requires placement of occlusive material directly into the nidus (core) of the lesion. Prohibitively complex proximal vasculature may prevent successful catheter positioning and lead to failure of traditional embolotherapy. Even optimal placement of arterial embolic material may fail to fully obliterate the nidus, allowing eventual restoration of flow to the lesion due to arterial recanalization. Under such circumstances it may be possible to obliterate the malformation and control lesional hemorrhage by occlusion of the malformation or its venous drainage by direct percutaneous mandibular puncture. In our case, multiple transarterial embolizations failed to sufficiently manage a symptomatic vascular malformation. Successful embolotherapy was performed via direct puncture of the venous side of the malformation through the mandibular cortex. Venous thrombosis induced concomitant occlusion of abnormal arteriovenous shunts, resulting in long-term control of life-threatening oral hemorrhage.

Contrast-enhanced MR of cerebral arteritis: intravascular enhancement related to flow stasis within areas of focal arterial ectasia

The authors present a case of probable amphetamine-induced cerebral arteritis in a 31-year-old man with AIDS, testicular carcinoma, and recurrent pneumocystis pneumonia. MR enhancement was demonstrated in areas of focal arterial ectasia, presumably due to slow flow. CT, MR, and angiographic findings were strikingly confirmed postmortem. Angiography remains essential in the diagnosis of cerebral arteritis.

Spinal arteriovenous malformation

The authors discuss a patient with a large (15 x 10 x 12 cm), bony soft tissue intradural arteriovenous malformation (AVM) who presented with a 20-year history of back pain. Plain radiographs revealed a destructive lesion. Magnetic resonance imaging showed serpentine vascular structures within the thecal sac and lytic bone lesions with multiple level involvement. A Craig needle biopsy by the referring physician, as well as an open biopsy by the authors, caused severe bleeding. There was no evidence of neoplasm. Selective spinal angiography demonstrated a metameric juvenile type AVM whose intradural component was fed by the artery of Adamkiewicz. Because the patient had no neurological deficit on presentation, the options of embolization and then surgery were considered too risky. The patient is being followed conservatively.

MR imaging of the normal and abnormal clivus

We retrospectively reviewed 330 T1-weighted sagittal images, 80 T2-weighted sagittal images, and 83 gadopentetate-dimeglumine-enhanced scans of normal adults to determine the MR appearance of the normal adult clivus. MR images of 21 patients with an abnormal clivus (19 with tumor invasion and two with marrow reconversion) were also evaluated retrospectively and compared with those of the control group to assess MR features distinguishing the two groups. Our study revealed that a normal adult clivus consisted of low- and high-intensity portions mixed in various proportions on T1-weighted images. The low-intensity portion was isointense or hyperintense relative to the pons and always contained foci of bright signal intensity. The low-intensity tumor of a pathologic clivus tended to be hypointense relative to the pons (17/19), and was completely devoid of foci of bright signal intensity. The normal adult clivus was approximately isointense relative to the pons on T2-weighted images. Clival tumors were grossly hyperintense relative to the pons on T2-weighted images in 11 of 17 patients. In the remaining six patients, either a portion of or the entire lesion was isointense relative to the pons and, therefore, was not detectable on T2-weighted images. A normal adult clivus can enhance to some degree (19/83). Clival tumors were found to enhance intensely. A clivus of very low signal intensity (signal void) on T1- or T2-weighted images was always abnormal. The clivus with marrow reconversion was uniformly hypointense relative to the pons on T1-weighted images and isointense relative to normal marrow on T2-weighted images. The intensity patterns of the normal clivus on T1- and T2-weighted MR images change predictably with advancing age. Intensity patterns of abnormal clivi differ from those of normal clivi. When contrast material is used, normal and abnormal clivi generally show different patterns of enhancement.

The pituitary "incidentaloma"

PURPOSE

To review evidence related to sellar masses that might be found incidentally on various radiologic procedures, including their differential diagnosis and recommendations for their evaluation and treatment.

DATA IDENTIFICATION

An English-language literature search using bibliographic reviews of textbooks and review articles.

STUDY SELECTION

Articles were selected on the basis of providing data on the autopsy prevalence of sellar masses, the radiologic and endocrinologic evaluation of such masses, and the prognostic aspects of pituitary adenomas.

DATA EXTRACTION

Twelve studies relating autopsy findings, 6 studies describing radiologic characteristics, and 26 articles reviewing various endocrine aspects of pituitary adenomas were evaluated.

RESULTS OF DATA SYNTHESIS

Pituitary adenoma is the most common incidental sellar mass. Scanning techniques are of great importance in differentiating the pituitary adenoma from other mass lesions. Autopsy and radiologic studies suggest that microadenomas (less than 10 mm in diameter) may be present in 10% to 20% of the population but that macroadenomas (greater than 10 mm in diameter) are quite rare. Hormone oversecretion by an adenoma may be asymptomatic but, when present, is very helpful in the differential diagnosis.

CONCLUSIONS

For adenomas found to be hypersecreting, therapy is as indicated for that specific tumor type. If there is no evidence of hormone oversecretion from microadenomas, we suggest a conservative approach with repeat scanning done at yearly intervals, initially, and subsequently less frequently. Macroadenomas, because they have already indicated some propensity for growth, should either be surgically removed or, if completely asymptomatic, followed closely with repeat scans at 6- to 12-month intervals.

Mineralization of the falx cerebri simulating interhemispheric vascular anomalies on MR imaging. Report of three cases

Three cases of ossification of the falx cerebri initially mistaken for vascular lesions based on their magnetic resonance (MR) appearance are reviewed. The MR imaging and computerized tomography characteristics of mineralization of the falx cerebri and their differentiation from interhemispheric vascular lesions are discussed.

Calcified synovial cyst of the cervical spine: CT and MR evaluation

A case of calcified synovial cyst of the cervical spine was diagnosed by a combination of imaging modalities. Curvilinear calcification associated with posterior elements, well seen by CT, suggested the correct diagnosis. Magnetic resonance showed a curvilinear region of low signal intensity corresponding to the calcification.