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Biomedical subjects

S W Atlas

Publications and source records attributed to S W Atlas.

At least 91 records · Page 5Linked to original sources
PubMed1986

Cervical spinal cord injuries in patients with cervical spondylosis.

Eighty-eight patients over age 40 with traumatic cervical spinal cord injuries were clinically and radiographically evaluated, and comparison was made with 35 spinal cord injury patients under age 36. While most older patients sustained obvious bony and/or ligamentous damage commensurate with their neurologic findings, 25 (28%) of the 88 patients had no demonstrable bony abnormalities and 17 (20%) of the 88 patients had only minimal evidence of bony injury. Of particular interest are the patients with severe cord injuries, yet no bony abnormalities, who seem to form a distinct subgroup of the cervical spinal cord injury patient on the basis of radiographic and clinical features. Of these 25 patients, 24 (96%) had severe cervical spondylosis. Fourteen (56%) of the 25 patients were injured in falls, five (36%) of these 14 being of a seemingly trivial nature. Of the 42 patients with minimal or no demonstrable bony abnormalities, 33 (79%) were evaluated with plain tomography and no occult fractures or other significant pathology was demonstrated. Pantopaque myelography in 27 (64%) of the 42 cases revealed no extruded disk or other surgical lesion in any patient. In large measure, these injuries can be attributed to cervical spondylosis, which narrows the canal and makes the cord more susceptible to compression by the bulging ligamenta flava during hyperextension.

Adolescent↗
PubMed1986

The radiographic characterization of burst fractures of the spine.

A retrospective review of 75 burst fractures of the spine was performed to define the radiographic features found on high-resolution CT, polytomography, and plain radiography and thereby allow full characterization of this uncommon spinal injury. Characteristic components of the injury include: centripetally oriented disruption of the vertebral body, unilateral or bilateral laminar fractures that abut the spinous process, marked anterior wedging, vertically oriented vertebral fracture emanating from the basivertebral foramen, increased interpediculate distance, and significant spinal canal narrowing by characteristic retropulsed fragments. Nearly all bursts occurred from T9 to L5; double bursts were present in less than 10% of cases. The usually present neurologic deficit nearly always corresponded to the level of the burst rather than to the frequently found noncontiguous associated spine fracture. Recent literature suggests that these complex fractures, which were initially thought to represent stable injuries, are often unstable. A subcategorization of burst fractures and their variants is proposed to explain this instability. An approach to the radiographic diagnosis of the spinal burst is proposed, and plain film clues to distinguish the burst fracture from the more common compression fracture are discussed. Representative cases are illustrated.

Adolescent↗
PubMed1985

Intraoperative sonography of the pancreas.

Intraoperative sonography (IOS) of the pancreas was performed in 12 patients, eight with known or suspected inflammatory disease and four with known or suspected malignancy, in order to assess its utility in aiding pancreatic surgery. In all eight patients with inflammatory disease, IOS provided additional information, aided in resection or biopsy, or identified structures that could not be evaluated by surgical dissection. IOS was particularly useful in these patients in determining the size and appearance of the pancreatic duct before dissection or ductography, thus allowing planning of appropriate pancreatic decompression or resection. It also was extremely helpful in locating and characterizing pseudocysts, including measurement of cyst wall thickness, and in directing needle aspiration of cyst contents. Adequate drainage of all cysts in multiple cystic masses was easily monitored. Finally, impalpable peripancreatic fluid collections and abscesses were often localized. In the four patients with probable malignancy, IOS was somewhat helpful in two, allowing exclusion of tumor in one and guiding biopsy in another. In the other two patients, IOS provided no information due to obvious local invasion and nonresectability. Results indicate a significant adjunctive role for IOS in surgery for inflammatory disease of the pancreas. It seems to be less helpful in patients with malignancy, probably because of the advanced stage of pancreatic carcinoma at the time of surgery.

Adult↗
PubMed1985

Sonographic recognition of agenesis of the corpus callosum.

Agenesis of the corpus callosum may be diagnosed successfully in vivo when sonograms demonstrate absence of corpus callosum; absence of pericallosal and cingulate sulci; "sunburst" pattern of sulci along the medial surface of the hemisphere; wide interhemispheric fissure; elevation of the third ventricle; small, laterally positioned frontal horns with concave medial borders; large, laterally positioned and inverted cingulate gyri; and Probst lateral callosal bundles. Comparison of necropsy specimens with sonograms from eight patients with callosal agenesis illustrates the anatomic basis for these diagnostic features.

Abnormalities, Multiple↗
PubMed1984

CT diagnosis of a mycotic aneurysm of the thoracoabdominal aorta.

The CT appearance of a mycotic aneurysm involving the thoracoabdominal aorta with adjacent vertebral osteomyelitis is presented. Specific CT features of the aneurysm, such as lack of intimal calcification and adjacent bone destruction or abscess, may allow the diagnosis to be made in the appropriate clinical setting.

Aneurysm, Infected↗
PubMedDate not supplied

MR diagnosis of acute disseminated encephalomyelitis.

High-field magnetic resonance (MR) imaging was performed in three patients with clinically diagnosed acute disseminated encephalomyelitis (ADEM). Contrast enhanced CT was normal in all cases. Magnetic resonance demonstrated multiple foci of demyelination in the brain stem, cerebrum, and cerebellum. Lesions were characteristic, in that they were relatively few in number, frequently present in the brain stem and posterior fossa, nonhemorrhagic, asymmetric, and easily correlated with clinical symptoms and signs. Follow-up MR in one patient who had clinically improved after steroid therapy showed marked resolution of previously documented lesions. Typical MR findings in combination with the appropriate clinical presentation can confirm the diagnosis of ADEM, obviate other more invasive diagnostic tests, identify the extent and sites of involvement, and follow response to therapy.

Adult↗
PubMedDate not supplied

MR imaging of intracranial metastatic melanoma.

Ten patients with intracerebral metastases from malignant melanoma were evaluated with magnetic resonance (MR) imaging performed at 1.5 T using spin-echo techniques. On the basis of histopathologic findings in three of 10 cases and CT appearances in all 10 cases, three patterns were identified on analysis of MR signal intensities in both short repetition time/echo time (TR/TE) and long TR/TE spin-echo scans. In comparison to normal cortex, nonhemorrhagic melanotic melanoma appeared markedly hyperintense on short TR/TE images and isointense, mildly hypointense on long TR/TE images. Nonhemorrhagic, amelanotic melanoma appeared isointense or mildly hypointense on short TR/TE and isointense or mildly hyperintense on long TR/TE images. Hemorrhagic melanoma varied in appearance, depending on the stage of hemorrhage. Melanotic, nonhemorrhagic melanoma can be distinguished from early and late subacute hemorrhage by its signal intensity on long TR/TE images. Spin-echo MR appears to be the method of choice for diagnosing melanotic metastases.

Brain Neoplasms↗
PubMedDate not supplied

Hemorrhagic intracranial retinoblastoma metastases: MR-pathology correlation.

Retinoblastoma is a highly curable tumor unless extraocular extension or metastases have occurred. Intracranial retinoblastoma metastases usually result from either contiguous or hematogenous spread and are rapidly fatal. We report two cases of pathologically proven, hemorrhagic intracranial retinoblastoma metastases and correlate magnetic resonance images with pathologic findings. Magnetic resonance with its high sensitivity and specificity for blood extravasation can document the associated hemorrhagic component of the tumor and help in the differentiation of nonmetastatic second neoplasms in retinoblastoma patients.

Brain Neoplasms↗
PubMedDate not supplied

Human malignant melanomas with varying degrees of melanin content in nude mice: MR imaging, histopathology, and electron paramagnetic resonance.

The etiology of the paramagnetic relaxation enhancement seen in malignant melanoma on proton magnetic resonance (MR) images has been the subject of many recent investigations and has been ascribed to iron from associated hemorrhage or chelated metal ions, rather than directly due to melanin. The purpose of this study was to correlate proton relaxation times on MR images in malignant melanomas with histopathologic features (i.e., degree of pigmentation, iron deposition, and necrosis), water content, and electron paramagnetic resonance (EPR) spectra to elucidate the etiology of the relaxation behavior demonstrated by these neoplasms. Cultured cells derived from human malignant melanoma metastases were implanted subcutaneously into nude mice. Twelve separate lesions were evaluated in 10 mice. Magnetic resonance imaging was performed in vivo at 1.9 T using spin echo and inversion recovery acquisitions for the purposes of calculating T1, T2, and proton density [N(H)]. Histopathologic examination was performed on specimens resected immediately after imaging, using hematoxylin/eosin, Prussian blue, and Fontana stains to assess tumor necrosis, and iron and melanin content. Dry/wet weight ratios and EPR spectra were also obtained on resected specimens. Our results indicate that T1 shortening correlates with increasing melanin content and not with increasing iron deposition, EPR-active metallic cations, necrosis, or water content. In fact, a presumably unrelated statistical correlation was found between increased iron and T1 prolongation. The T2 relaxation times did not correlate with the presence of any single factor other than proton density. Although the unique relaxation behavior of nonhemorrhagic malignant melanoma in vivo cannot be traced to a single cause, our data suggest that, contrary to previous investigations, it is strongly influenced by the presence of melanin rather than iron or other naturally occurring paramagnetic ions.

Animals↗
PubMedDate not supplied

Gd-DTPA enhancement of the cisternal portion of the oculomotor nerve on MR imaging.

PURPOSE: To describe a radiographic finding--enhancement of the cisternal portion of the third cranial nerve on postcontrast MR--and to correlate it with patients' clinical symptoms and ultimate diagnosis. MATERIALS AND METHODS: Thirteen consecutive patients with enhancement of the cisternal portion of the third cranial nerve on postcontrast MR were retrospectively identified; 50 control patients referred for pituitary microadenomas were also retrospectively reviewed. FINDINGS: The enhancement was bilateral in six patients and unilateral in seven patients. Four of the six patients with bilateral enhancement had unilateral oculomotor nerve palsies; none had bilateral third cranial nerve palsy. Five of the seven patients with unilateral enhancement had ipsilateral third nerve palsies. Of the nine patients with third nerve palsies, the pupil was involved in four patients. Follow-up studies were available in six patients, four of whom had third nerve palsy. Resolution of the enhancement correlated with resolution of the symptoms in two patients. The patients' underlying diagnoses were lymphoma (four), leukemia (one), viral meningitis (one), neurofibromatosis (two), inflammatory polyneuropathy-HIV related (one), ophthalmoplegic migraine (one), Tolosa-Hunt syndrome (one), coccidioidomycosis (one), and diabetes (one). No enhancement was seen in any of the controls. CONCLUSION: Enhancement of the cisternal segment of the third cranial nerve is always abnormal, revealing an underlying inflammatory or neoplastic process. However, it is not always associated with clinically apparent oculomotor nerve dysfunction.

Adult↗
PubMedDate not supplied

Cervical spine disk herniation: comparison of CT and 3DFT gradient echo MR scans.

The purpose of this study was to compare CT and MR for the detection of cervical disk herniations. Nineteen patients suspected of harboring degenerative disk disease of the cervical spine underwent thin contiguous section CT myelography (CTM) and thin contiguous section three-dimensional Fourier transform (3DFT) gradient echo MR at 67 disk levels. Blinded readings of a high intensity CSF MR technique for the presence or absence of disk herniation were performed by three neuroradiologists. The intraobserver CT-MR concordances ranged from 84 to 89%. Using CTM as the paragon test, MR demonstrated a sensitivity of 79-91% and a specificity of 82-88% for disk herniation. Mean MR-CT concordance (86%) was nearly equivalent to that of CT-CT intraobserver concordance (88%). When consensus readings were considered, the MR-CT concordance (91%) was slightly higher than that of CT-CT intraobserver concordance (88%). We conclude that thin section 3DFT gradient echo MR with high intensity CSF is a reliable method to screen for degenerative disk disease in the cervical spine, since the agreement between MR and CTM is comparable with the intraobserver agreement of CTM.

Cervical Vertebrae↗
PubMedDate not supplied

CNS sarcoidosis: evaluation with contrast-enhanced MR imaging.

Reports of findings on unenhanced MR images and contrast-enhanced CT scans in patients with intracranial sarcoidosis have suggested that MR imaging without contrast enhancement may miss meningeal involvement, which is a frequent and prominent finding in neurosarcoidosis. We studied 14 patients with CNS sarcoidosis with T1- and T2-weighted pre- and postcontrast sequences and T1-weighted postcontrast sequences. Eight of 12 patients with intracranial sarcoidosis and one of two with spinal sarcoidosis had meningeal involvement that was not apparent on the unenhanced scans. Eight of 12 patients had intraaxial areas of high signal intensity on T2-weighted images, although only two of these lesions enhanced. Three patients had enhancing extraaxial masses mimicking meningiomas on postcontrast T1-weighted images. In two patients, the lesions decreased markedly in size after steroid treatment. In one patient with sarcoidosis of the optic nerve, the lesion decreased in size and the patient's vision returned to normal after Cytoxan therapy. In five of 14 patients, CNS findings were the initial clinical manifestation of the disease. In nine of 14 patients, the diagnosis of neurosarcoidosis was suggested only after administration of contrast agent. Use of gadopentetate dimeglumine greatly enhances the sensitivity of MR imaging in the detection of CNS sarcoidosis.

Adolescent↗
PubMedDate not supplied

Degenerative narrowing of the cervical spine neural foramina: evaluation with high-resolution 3DFT gradient-echo MR imaging.

Conventional two-dimensional Fourier transform (2DFT) MR evaluation of osteophytic disease of the cervical neural foramina is limited by section thickness, signal-to-noise problems, and CSF flow artifacts. We evaluated the role of thin-section, high-resolution, gradient-refocused three-dimensional Fourier transform (3DFT) MR imaging in assessing degenerative foraminal narrowing in the cervical spine. Contiguous 1.5-mm axial 3DFT gradient-recalled acquisition in the steady state MR images of 120 neural foramina at 60 disk levels were evaluated blindly and independently by three neuroradiologists. High-resolution axial CT was used as the gold standard in all patients. 3DFT MR was found to agree with CT in the detection of neural foraminal narrowing and in the determination of the cause of the narrowing in approximately 76% of neural foramina. The accuracy for the assessment of neural foraminal narrowing on 3DFT MR ranged from 73% to 82% when a 5 degrees-flip-angle, high-intensity CSF technique was used. When using the 30 degrees-flip-angle, low-intensity CSF technique, the accuracy ranged from 66% to 86%. When the cause of narrowing was evaluated, the 5 degrees and 30 degrees studies agreed with CT in 70-92% and 48-88% of the levels, respectively. When lesions were missed on MR, it was usually because of osteophytic disease. The interobserver concordance of MR and CT interpretations was higher for detecting the presence of narrowing than its cause. This MR technique is a useful method in the evaluation of foraminal stenosis since contrast between disk, cord, osteophyte, and CSF is high without the need for intrathecal injections.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Paradoxically decreased signal intensity on postcontrast short-TR MR images.

Seven lesions are presented in which short TR/short TE images obtained immediately after IV administration of gadopentetate dimeglumine demonstrated an apparent decrease in signal intensity compared with precontrast short TR/short TE images. All seven lesions were hyperintense on precontrast short TR/short TE images. In four cases in which long TR/long TE scans were also obtained, the lesions were hypointense. This phenomenon may be due to a dominant T2 shortening effect by the contrast material that "overwhelms" T1 shortening even on short TR/short TE scans. Other compounding factors may include variations in scanning variables, receive and transmit attenuations, or a photographic phenomenon due to window widths and center levels.

Contrast Media↗
PubMedDate not supplied

MR evaluation of brain iron in children with cerebral infarction.

Young children and infants normally have essentially no detectable brain iron. We evaluated brain iron patterns on 23 MR scans in 20 patients under 6 years of age with clinical and MR-documented cerebral infarctions in an attempt to further understand the neuropathologic phenomenon of increased iron deposition, which has been observed in other disease states. MR was performed at 1.5 T with spin-echo sequences from 1 day to 4 years after infarction. MR scans were interpreted without knowledge of clinical information and were assessed for (1) location and character (i.e., bland or hemorrhagic) of infarct, and (2) nonheme iron (i.e., marked hypointensity on long TR/TE images) in the basal ganglia, red nuclei, substantia nigra, thalami, dentate nuclei, and deep white matter. Sixteen of 20 infarctions were associated with increased iron. Six of seven cases with unilateral iron deposition had ipsilateral infarctions. The location (deep versus cortical) and age of the infarction had no apparent bearing on iron patterns. We conclude that increased brain iron is commonly associated with cerebral infarction and is nonspecific, rather than a marker of movement disorders. Since iron may arise from either interruption of transport pathways or directly from cell injury and, in fact, iron itself may propagate the tissue injury, this finding may have important clinical and pathophysiologic implications in ischemic brain injury.

Brain↗
PubMedDate not supplied

Pseudoatrophy of the cervical portion of the spinal cord on MR images: a manifestation of the truncation artifact?

Routine evaluation of axial MR images of the cervical spine with high-intensity CSF (long TR/TE spin-echo or gradient-echo images) revealed apparent narrowing of the cord's anteroposterior diameter when these images were compared with corresponding postmyelography CT scans. This discrepancy was believed to be due to the truncation artifact at the CSF-cord boundary. To examine the truncation effect, we compared cord diameters in 12 patients on postmyelography CT scans and MR images and then compared these with MR scans of normal volunteers and of an agar-saline spine phantom. There was an artifactual diminution of the cord diameter in the 128-step phase-encoding axis of the 128 x 256-matrix MR scan as compared with the diameter of the cord in the patients' postiohexol CT scans and in the 256 phase-encoded axis MR scan in the volunteer study. A similar discrepancy was noted in the spine phantom study, in which the cord diameter in the 256-step phase-encoded MR scan, the CT scan, and direct measurement exceeded that in the 128-step phase-encoded axis MR scan. The range of differences between the measurements was as large as 2.3 mm (patients), 1.7 mm (volunteers), and 1.8 mm (phantom) for the three studies. In all three studies, varying the photographic window width and level produced variation in the apparent cord diameter of up to 1.5 mm. To eliminate this effect, the cord diameters in the phantom and the normal control subjects were measured at identical window levels. The truncation artifact, coupled with standard window settings used in photography, may lead to inaccurate display of the diameter of the cervical spinal cord.

Humans↗