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Biomedical subjects

D O Davis

Publications and source records attributed to D O Davis.

At least 19 recordsLinked to original sources
PubMed1992

Contrast-enhanced MR imaging performed after successful lumbar disk surgery: prospective study.

A prospective study was undertaken to establish the normal spectrum and timing of gadolinium-enhanced magnetic resonance (MR) imaging findings in 15 patients who had resolution of symptoms after successful lumbar disk surgery. Enhancement of the facet joints (in 88% of disk levels) and paraspinal muscles (100%) decreased gradually after surgery. Enhancement of the decompressed nerve root tracked proximally toward the conus medullaris in 62% at 3 weeks and was absent in all by 6 months postoperatively. Areas of intermediate signal intensity with peripheral enhancement and mass effect were seen on T1-weighted images at the site of the original disk herniation in 38% at 3 weeks and 12% at 3 months, despite complete relief of leg pain. These results reveal that even in successfully treated (asymptomatic) patients, residual mass effect on the neural elements may frequently simulate a recurrent or residual disk fragment. There is an orderly progression of imaging changes during the first 6 months after lumbar surgery that limits the interpretation of MR examinations during that period.

Adult↗
PubMed1992

Postoperative diskitis: distinguishing early MR imaging findings from normal postoperative disk space changes.

To distinguish early magnetic resonance (MR) imaging findings in postoperative diskitis from normal postoperative changes, a prospective study was performed in 15 asymptomatic patients (17 disk levels) who underwent uncomplicated lumbar diskectomy and seven patients with proved postoperative diskitis. On postoperative MR images, four of the asymptomatic patients had a finding that could also be seen in patients with diskitis. Gadolinium enhancement was useful in making the distinction and occurred as follows: (a) vertebral bone marrow: all seven diskitis patients and one asymptomatic patient; (b) disk space: five diskitis patients and three asymptomatic patients; and (c) posterior anulus fibrosus: all seven diskitis patients and 13 asymptomatic patients (14 of 17 levels). This entire triad of findings, which is strongly suggestive of postoperative diskitis, was not seen in any of the asymptomatic patients. Changes in the disk space and adjacent bone marrow on pre- and post-contrast MR images after routine diskectomy are uncommon and should not be assumed to be normal postoperative changes without careful consideration and analysis for early diskitis.

Adult↗
PubMed1992

A prospective and blinded investigation of magnetic resonance imaging of the knee. Abnormal findings in asymptomatic subjects.

To evaluate magnetic resonance imaging (MRI) of meniscal, ligamentous, and bony abnormalities in patients without clinical symptoms, scans were performed on 74 asymptomatic volunteers without histories or symptoms of knee injury. Before review by three radiologists in an independent and blinded fashion, the scans were mixed with 26 MRI scans from symptomatic patients. Sixteen percent of the asymptomatic volunteers had meniscal abnormalities consistent with a tear. The prevalence of MRI findings of a meniscal tear increased from 13% in individuals younger than 45 years of age to 36% in those older than 45. An additional 30% of the volunteers showed meniscal abnormalities consisting of a linear area of increased MR signal not communicating with a meniscal edge, which was not interpreted to represent a tear. The high incidence of abnormal MRI findings in asymptomatic subjects underscores the danger of relying on a diagnostic test without careful correlation with clinical signs and symptoms. These findings also emphasize the importance of access to relevant clinical data when interpreting MRI scans of the knee.

Adolescent↗
PubMed1991

Gd-DTPA-enhancement magnetic resonance imaging of the cavernous sinus.

Based upon our experiences with 7 cases and a literature review a survey is provided on the possibilities and limitations of preoperative diagnosis of space-occupying lesions of the cavernous sinus using MRI with Gd-DTPA enhancement. Advantages are, that in many cases arteriography is no longer necessary, and that the diagnostic sensitivity is higher as compared with CT. The pattern of enhancement does not allow for histological distinction among the various lesions.

Adult↗
PubMed1979

Acute isodense epidural hematoma on computed tomography.

Computed tomography (CT) has proven to be invaluable in the diagnosis of craniocerebral injuries. Acute epidural hematomas have been described as having a characteristic appearance on CT of a lenticular shaped area of blood density most commonly situated over the cerebral convexity. This case demonstrates an acute epidural hematoma that is essentially isodense with brain tissue.

Adult↗
PubMed1979

Cranial CT findings in patients with meningomyelocele.

The association between meningomyelocele and various cranial abnormalities, particularly Chiari II malformation is well established. Cranial CT scans in 47 patients with meningomyelocele proved to be a safe and effective method of elucidating the type and extent of anatomic abnormalities associated with this disorder, and evaluating and following the degree of hydrocephalus seen in these patients. Of the 47 patients, 43 (92%) showed CT findings indicative of an abnormally low fourth ventricle, the hallmark finding in Chiari II malformation. In 67% the fourth ventricle was not visualized, and in 25% it was directly visualized in an abnormally caudal position. Other findings included hydrocephalus (85%), a striking and possibly unique heart-shaped psuedomass in the posterior fossa (58%), and abnormal configuration of the lateral ventricles ("vampire bat" configuration). Calvarial abnormalities, in particular lacunar skull, were also noted at CT.

Abnormalities, Multiple↗
PubMed1979

Subdural hematomas: an unusual appearance on computed tomography.

It may at times be difficult to separate supra- from infratentorial and intra- from extraaxial pathology on the basis of axial transverse computed tomography (CT) scans. Coronal CT scans may be quite useful in more accurate localization of compartments. Three head injured patients with subdural hematomas were studied with axial transverse CT scans. In addition to the typical appearance of subdural hematomas, unusually shaped areas of increased attenuation were noted in the region of the tentorium cerebelli separate from the mass of the subdural collection. Coronal scans confirmed the supratentorial, extraaxial collection as an extension of the subdural hematoma into the supratentorial subdural space.

Cerebral Ventriculography↗
PubMed1978

Utilization and cost-effectiveness of cranial computed tomography at a university hospital.

This study prospectively surveyed the utilization of cranial computed tomography (CCT) at The George Washington University Hospital over a 12-month period. Of 3,070 CCT scans studied, 1,098 (35%) resulted in a positive clinically important diagnosis for an overall case finding cost of $800. Within each of 25 individual indications for scanning, classified on the basis of the patient's most specific sign or symptom, case finding costs varied from a low of $411 for patients in coma to $3,500 for patients with headaches as their only indication for CT scanning. Within two diagnostic categories, malignant brain tumors and cerebral aneurysms, there was significant agreement (p less than 0.001) between the prescanning diagnosis and the result on CCT. Overall there was also close agreement (correlation coefficient = 0.706) between the rank listing of the 25 indications for scanning compiled prior to CCT with that obtained after the scanning results were known.

Adolescent↗
PubMed1977

Scleral thickening: a CT sign of orbital pseudotumor.

Orbital pseudotumor is a benign inflammatory lesion of the orbit. Computed tomography is a new method for evaluation of orbits. Scleral uveal rim thickening with contrast enhancement was found in eight of 15 patients with pseudotumor (53%). Similar rim thickening was seen in one postoperative patient and two cases of recent trauma. Therefore, the sign presumably represents inflammation. It was not seen in 47 cases of thyroid disease and 66 cases of neoplasm.

Bone Diseases↗
PubMed1975

Posterior fossa hemorrhage. Localization by computerized tomography.

The differentiation between pontine and cerebellar hemorrhage is important both prognostically and therapeutically but is often very difficult. Computerized axial tomography of the brain is a new, rapid, nonivasive method of studying intracranial disease. This technique proved useful in making this important differential diagnosis in the case reported here.

Cerebral Hemorrhage↗
PubMed1975

An accessory table for supine horizontal-beam polytome laminagraphy.

A two-part accessory table for use with the Philips Polytome is described. It permits brow-up lateral polytomography and submentovertex examinations to be carried out with the patient resting comfortably. Accuracy to 1 mm in positioning of the tomographic section is maintained.

Humans↗
PubMed1975

A head-holding device for computed tomography.

The authors describe a chin holder, modified from a commercially available encephalography chair, which significantly decreases head movement and resultant motion artifacts during computed tomography.

Humans↗