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Biomedical subjects

R M Scott

Publications and source records attributed to R M Scott.

277 records · Page 16Linked to original sources
PubMedDate not supplied

Difficulties in diagnosing congenital posterior fossa fluid collections after shunting procedures.

The differential diagnosis of retrocerebellar fluid collections in infants is important because of the prognostic implications. Usually the diagnoses are easy; however, shunting of the lateral ventricles or of the fluid collections may alter the appearance of the lesions, precluding accurate diagnosis. Under such circumstances a careful study of all the sequential radiologic studies is necessary.

Cerebellum↗
PubMedDate not supplied

MR evaluation of neurovascular lesions after endovascular occlusion with detachable balloons.

Three patients with surgically inaccessible giant carotid aneurysms/pseudoaneurysms and one patient with carotid cavernous fistula had endovascular occlusion with detachable silicone balloons filled with Cholografin. MR was performed before the procedures in three cases and again 18 hr to 44 days after embolization in all four cases. The age-related changes of arterial thrombi, as well as the optimal timing and value of different pulse sequences in the noninvasive follow-up, were evaluated. Arterial thrombi have some characteristics in common with intracerebral hematomas, being isointense on T1-weighted spin-echo images during acute phase and subsequently acquiring hyperintense signals on both T1- and T2-weighted spin-echo images during the subacute and chronic phases. Additional observations are that (1) hyperacute (less than 24 hr old) thrombus is hyperintense on T2-weighted spin-echo sequences; (2) hemosiderin is less conspicuous in chronic intraluminal thrombi than in intracerebral hematomas of comparable size; and (3) thrombosis is initiated at a site remote from the apex of the aneurysm and then progresses centripetally. The Cholografin-filled balloon is hypointense to gray matter on T1-weighted spin-echo images and isointense to both hyperacute and chronic thrombus on T2-weighted spin-echo images. The optimal timing and sequence for MR follow-up of a thrombosed aneurysm with conventional spin-echo technique is beyond 7 days on T1-weighted spin-echo images. The in vivo appearance of Cholografin-filled silicone balloons does not change appreciably on T1- and T2-weighted spin-echo sequences up to 6 weeks if filled according to the manufacturer's specification.

Adult↗
PubMedDate not supplied

The clinical significance of hindbrain herniation and deformity as shown on MR images of patients with Chiari II malformation.

This study investigates whether the degree of brainstem herniation and the nature of the cervicomedullary deformity seen on sagittal plane MR images correlates with the clinical syndrome in patients with the Chiari II malformation. The amount of brainstem herniation was assessed by relating the position of the midbrain and pons to the sella turcica and the anterior lip of the foramen magnum, respectively. The cervicomedullary deformity was graded into degrees of increasing severity. We found that the neurologic status of these children was not affected by either the amount of herniation or the characteristics of the cervicomedullary deformities. Because of these findings, we believe that other factors, such as disorganization of the brainstem nuclei, may be the likely cause for the breathing and swallowing difficulties experienced by children with the Chiari II malformation.

Adolescent↗
PubMedDate not supplied

The value of metrizamide CT cisternography in the management of cerebral arachnoid cysts.

Arachnoid cysts may or may not communicate with the cerebrospinal fluid pathways. Patterns of communication were studied in six patients, using metrizamide computed tomography (CT) cisternography, ventriculography, and cystography. Two types of cysts were found: one with free communication with the cerebrospinal fluid pathways and one with restricted communication. This information can be useful in the surgical management of the cysts. When the cysts freely communicate wih the ventricles, ventricular shunting is the appropriate therapy, whereas when the cysts are noncommunicating, direct shunting of the cyst is indicated.

Adolescent↗
PubMedDate not supplied

Pediatric and adolescent oligodendrogliomas.

PURPOSE: To review the clinical and imaging findings in pediatric and adolescent intracranial pure oligodendrogliomas. METHODS: The clinical, CT, and MR data in 39 surgically proved pure oligodendrogliomas were retrospectively reviewed. RESULTS: The frontal or temporal lobes were involved in 32 (82%) cases. Seventy percent of the tumors were hypodense on CT, three-fourths were hypointense on T1-weighted images, and all were hyperintense on spin-density and T2-weighted images. Fewer than 40% of the lesions demonstrated calcification, and nearly 60% had well-defined margins. Mass effect was seen in fewer than half of the cases, and edema could be separately identified in only one case. Tumor enhancement was seen in fewer than 25%. In 39 cases after partial (3), subtotal (16), or total (20) resection, follow-up studies demonstrated stability over a mean period of 5 years. CONCLUSION: The findings in this pediatric series of pure oligodendrogliomas (without mixed cell elements) differ from previous adult series in that calcification, contrast enhancement, and edema are seen less frequently. In addition, very slow or no growth is often characteristic, and these patients have an excellent prognosis with surgical resection.

Adolescent↗
PubMedDate not supplied

Hemorrhagic pituitary adenomas of adolescence.

PURPOSE: To review the clinical and MR imaging findings in adolescents with hemorrhagic pituitary adenomas and to compare those findings with pathologic results and outcome. METHODS: We reviewed the clinical records, imaging examinations, surgical and pathologic findings, and follow-up studies in 11 girls and six boys (12 to 20 years old; mean age, 16 years) with pituitary adenomas who were treated at our institution between August 1986 and June 1995. RESULTS: Of the 17 adenomas, eight were macroadenomas (> 1 cm) in patients 14 to 18 years old (three girls, five boys). Six of the macroadenomas were grossly hemorrhagic, and appeared as high-intensity intrasellar/suprasellar masses on all MR sequences obtained before definitive diagnosis and treatment. Clinical presentation in the patients with the hemorrhagic macroadenomas included headache (five), visual field deficits (three), and neuroendocrine symptoms (three). One patient was asymptomatic. The preliminary clinical and imaging diagnoses were craniopharyngioma or Rathke's cyst in five of the six cases. Pathologic diagnoses were prolactinoma in four patients, plurihormonal (prolactin/follicle-stimulating hormone) tumor in one patient, and nonfunctioning adenoma in one patient. Surgical resection was performed in all six hemorrhagic tumors and radiation therapy was required in three cases. CONCLUSION: Pituitary adenomas uncommonly occur in childhood and are usually seen in adolescence. The majority of the macroadenomas are hemorrhagic and often occur in male subjects. The clinical and MR imaging features may mimic craniopharyngioma or Rathke's cyst. These tumors often require surgery and/or radiation therapy.

Adenoma↗