Biomedical subjects
Publications and source records attributed to H T Doan.
The CT and MR appearance of a case of low-grade adenocarcinoma of probable endolymphatic sac origin is presented. The tumor destroyed a large part of the posterior temporal bone and showed prominent extension into the posterior cranial fossa.
A retrospective analysis of magnetic resonance (MR) imaging studies of 78 patients with acute cervical spinal cord injuries was undertaken to determine which observations related directly to the neurologic injury. All MR imaging studies were performed on a 1.5-T unit and assessed with respect to 14 parameters related to the bony spine, ligaments, prevertebral soft tissues, intervertebral disks, and spinal cord. Forty-eight patients also underwent non-contrast material-enhanced thin-section computed tomography (CT) of the cervical spine. MR imaging was the definitive modality in the assessment of soft-tissue injury, especially in the evaluation of the spinal cord and intervertebral disks. All patients with a neurologic deficit had abnormal spinal cords at MR imaging. Intramedullary hemorrhage was predictive of a complete lesion. The degree of associated bone and soft-tissue injury had no bearing on the extent of spinal cord injury or neurologic deficit. Patients with residual cord compression following reduction demonstrated greater neurologic compromise than those without compression.
Prior to the advent of computer-assisted imaging techniques, conventional radiographic studies did not accurately depict the severity of soft tissue injury (spinal cord and paravertebral tissue) attending severe spinal trauma. Computed tomography scanning is clearly superior to plain radiography in the demonstration of osseous fractures and impactions, but this modality does not clearly depict ligamentous or disc injuries and does not image the spinal cord directly. The authors' preliminary experience indicates that magnetic resonance imaging (MRI) more accurately defines the extent of soft tissue damage in the zone of injury. In this study, the authors correlate these objective imaging techniques with findings on neurologic exam. Seventy-eight patients with cervical spine injuries admitted to the Regional Spinal Cord Injury Center of the Delaware Valley between August 1987 and January 1989 were evaluated with surface-coil MRI on a 1.5-Tesla unit. Fifty-nine patients were studied within 7 days of injury. Image sequences consisting of T1-, proton density, and T2-weighted images were obtained in saggital views. Axial gradient recalled acquisitions in the steady state (GRASS) images were obtained from most patients. We learned that certain patterns of MRI signal were associated with severe neurologic deficit. These include: 1) intramedullary hematoma and 2) spinal cord contusion associated with edema encompassing more than one spinal segment. Magnetic resonance imaging findings also correlated with less severe injury and include 1) normal spinal cord signal and 2) small focal contusions associated with edema encompassing one spinal segment or less.
A case is presented in which a solitary chondroma arose from the clivus of a patient with Ollier's disease. These tumors are rare. The diagnostic value of computerized tomography and magnetic resonance imaging is discussed.
Although exostoses of the external auditory canal are not uncommon, those of the internal canal are extremely rare. One of these is described occurring in a 53-year-old man whose rapidly progressive hearing loss was without any associated abnormality.
Noninvasive procedures (ultrasound, CT, and MRI) are increasingly valuable in the diagnosis of diseases of the head and neck. Angiography, however, is still essential in the demonstration of vascular pathology, including the preoperative evaluation of vascular neoplasms. Through angioplasty and embolization techniques, angiography also plays a leading role in the treatment of arteriosclerotic vascular disease, vascular malformations, and vascular neoplasms.
The CT signs of aberrant course of the internal carotid artery are presented and are contrasted against those of anomalously high jugular bulb, glomus tympanicum and cholesterol granuloma.
We retrospectively reviewed the routine spin-echo MR studies of the brain in 12 patients with 13 angiographically demonstrated occlusions and in 14 patients with 16 high-grade stenoses of the carotid arteries. Intraluminal signal that was isointense with adjacent brain on long TR/short TE and long TR/long TE images was 100% specific for atherosclerotic occlusion. Of the 13 proved occlusions, six (46%) had significant degrees of hyperintense intraluminal signal indistinguishable from that observed consequent to slow flow distal to high-grade stenoses. MR detected only five (31%) of the 16 proved high-grade stenoses. Normal flow void does not exclude significant extracranial carotid stenosis. Occlusion cannot always be distinguished from high-grade stenosis when hyperintense intraluminal signal is encountered. However, a reliable diagnosis of atherosclerotic occlusion can be made when isointense intraluminal signal is observed.
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