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Biomedical subjects

D M Yousem

Publications and source records attributed to D M Yousem.

At least 91 records · Page 5Linked to original sources
PubMed1991

Proliferative retinopathy: absence of white matter lesions at MR imaging.

One form of retinopathy associated with diabetes is a proliferative small vessel process thought to be mediated by biochemical, hemodynamic, and endocrinologic factors. The authors conducted a prospective study to determine whether patients with diabetes who had proliferative retinopathy had evidence of intracranial microangiopathy visible at magnetic resonance (MR) imaging. Twenty-five patients under 40 years of age with proliferative retinopathy and insulin-dependent diabetes mellitus and 10 age-matched control subjects were studied with MR imaging. Axial images were reviewed by two neuroradiologists for the presence of white matter foci of high signal intensity. No patients demonstrated evidence of these foci. There was no evidence of ischemic foci in any of the patients (all patients were neurologically asymptomatic). The vasculopathy associated with proliferative retinopathy does not appear to affect the intracranial circulation to the extent detectable with MR imaging. The presence of white matter foci of high signal intensity or ischemic changes in the brains of insulin-dependent diabetic patients under 40 years of age should not be attributed to diabetic vasculopathy. Other causes should be considered.

Adolescent↗
PubMed1991

Ostiomeatal complex risk factors for sinusitis: CT evaluation.

The ostiomeatal complex was prospectively evaluated in 100 consecutive patients referred for CT scanning. The degree of nasal septal angulation, uncinate process deviation (U-VS angle), infundibular and middle meatus opacification were correlated with maxillary and ethmoid sinus opacification. Patients with more severe nasal septal deviation and more horizontally-oriented uncinate processes had a higher frequency of sinus opacification. However, the differences between patients with and without CT evidence of sinus disease were very small (1.7 degrees to 3.4 degrees). Infundibular opacification most accurately predicted maxillary (76%), and middle meatus opacification most accurately predicted ethmoid sinus disease (78%). There is a small but statistically significant decrease in U-VS angulation and increase in nasal septal deviation in patients with sinusitis. However, the value of performing these measurements is limited. The evaluation of the degree of nasal septal deviation and uncinate process angulation will be most useful in preoperative planning.

Causality↗
PubMed1990

Bright lesions on sellar/parasellar T1-weighted scans.

Eighty-seven patients with sellar and parasellar pathology were evaluated by magnetic resonance imaging to categorize lesions with hyperintensity on T1-weighted images. Postoperative fat packing after transsphenoidal hypophysectomy, intratumoral subacute or chronic hemorrhage in pituitary adenomas, and hemorrhagic or fat-containing craniopharyngiomas accounted for 33 of 35 abnormalities with short T1 values. Forty-three percent of nonsurgically treated pituitary adenomas had subacute intratumoral hemorrhage present. Using T2-weighted images to distinguish fat from subacute hemorrhage and attempting to identify the normal anterior pituitary gland on T1-weighted images may help to differentiate these three entities. T1-weighted images alone were not sufficient to distinguish between all sellar and parasellar masses.

Adenoma↗
PubMed1990

Rhabdomyosarcomas in the head and neck: MR imaging evaluation.

To determine the typical magnetic resonance (MR) signal intensity characteristics of rhabdomyosarcomas, short repetition time (TR)/short echo time (TE) (T1-weighted) and long TR (proton density and T2-weighted) images of 13 patients with rhabdomyosarcomas of the head and neck were retrospectively reviewed. Seven patients received gadopentetate dimeglumine injections. The most common MR appearance was that of a homogeneous mass, hyperintense to both muscle and fat on long TR/long TE images and isointense or minimally hyperintense to muscle on short TR/short TE images. All lesions of the patients who received gadopentetate dimeglumine enhanced markedly. Two lesions had intratumoral hemorrhage, and six were markedly heterogeneous in signal intensity. Similar MR signal intensity patterns have been described for lymphomas and nasopharyngeal carcinomas. The forte of MR imaging lies in its ability to delineate precisely the extent of the rhabdomyosarcoma.

Child↗
PubMed1990

MR imaging of Tolosa-Hunt syndrome.

The Tolosa-Hunt syndrome consists of painful ophthalmoplegia caused by cavernous sinus inflammation, which is responsive to steroid therapy. The MR features of 11 patients with the clinical diagnosis of Tolosa-Hunt syndrome were studied. Two patients had normal MR studies of the orbit and cavernous sinuses. In nine patients, abnormal signal and/or mass lesions were seen in the cavernous sinuses; in eight cases, the abnormality was hypointense relative to fat and isointense with muscle on short TR/TE images and isointense with fat on long TR/TE scans. Extension into the orbital apex was seen in eight cases. In six of nine cases the affected cavernous sinus was enlarged; in five of nine it had a convex outer margin. One patient had a thrombosed cavernous sinus and superior ophthalmic vein in addition to a cavernous sinus soft-tissue mass. The signal intensity of Tolosa-Hunt syndrome in this limited series was similar to that of orbital pseudotumor and is confined to a limited differential diagnosis, which includes meningioma, lymphoma, and sarcoidosis.

Adolescent↗
PubMed1990

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.

Atrophy↗
PubMed1989

Treated invasive cervical carcinoma. Utility of computed tomography in distinguishing between skeletal metastases and radiation necrosis.

The bony pelvis should be carefully evaluated on computed tomography (CT) scans of the lower abdomen and pelvis performed for staging cervical cancer or for evaluating suspected recurrence. CT provides optimal imaging of the spine and pelvis, frequently providing a clinically relevant supplement to bone scan or plain film information. In a study of eight patients with skeletal metastases from cervical carcinoma and three cases of radiation osteitis, overlap existed in their imaging characteristics. Metastases were always lytic but nearby sclerotic areas from radiation were often present. Radiation osteitis may be lytic, sclerotic, or mixed, and both may avidly accumulate bone-scanning radiotracers. The absence of a soft tissue mass, slow progression, blastic elements, and sharply defined borders on CT suggest radiation necrosis. However, in some lesions within a radiation portal, biopsy or MRI may be required for final diagnosis.

Bone Diseases↗
PubMed1989

Pituitary adenomas: possible role of bromocriptine in intratumoral hemorrhage.

Magnetic resonance (MR) images of 68 patients examined for adenomas of the pituitary gland were retrospectively reviewed for the presence of hyperintensity on T1-weighted images because of recent reports suggesting that bromocriptine treatment may affect T1 values. Twenty-seven patients were examined after either surgery or radiation therapy, 29 were receiving bromocriptine, and 22 had not received any treatment at the time of MR imaging. MR imaging criteria showed evidence of subacute or chronic intratumoral hemorrhage in 18 patients, five of whom had hemorrhage proved at surgery. Ten of the 18 patients were asymptomatic from the hemorrhage; eight had headaches, visual field cuts, or cranial nerve deficits. Although an increased frequency of intratumoral hemorrhage was noted in prolactinomas and macroadenomas and in patients undergoing bromocriptine therapy, the effect of bromocriptine on bleeding was the only significant correlation (P less than .01).

Adenoma↗
PubMed1988

Crohn disease: perirectal and perianal findings at CT.

The computed tomographic scans of 200 consecutive patients with Crohn disease were studied to determine the frequency and patterns of perirectal and perianal involvement. In 163 patients (82%) abnormalities in the perirectal-perianal region were demonstrated; findings included inflammation of fat planes (73%), bowel wall thickening (30%), fistulas or sinus tracts (22%), and abscesses (14%). Fistulas or sinus tracts occurred with equal frequency above or below the level of the anterior symphysis pubis. Abscesses, rectal thickening, and inflammatory infiltration of fat occurred more than twice as often above the symphysis pubis. However, 37% of patients had manifestations of Crohn disease below the symphysis pubis, emphasizing the importance of extending scanning sequences to the perineum.

Anal Canal↗
PubMed1988

Synchronous and metachronous transitional cell carcinoma of the urinary tract: prevalence, incidence, and radiographic detection.

Six hundred forty-five cases of transitional cell carcinoma (TCC) of the bladder, ureter, and/or kidney were reviewed retrospectively to determine the frequency of synchronous and metachronous lesions elsewhere in the urinary tract. Among 597 patients with TCC of the bladder, 23 (3.9%) developed an upper-tract lesion, after an average delay of 61 months. Metachronous upper-tract tumors developed in 13% of 38 patients with primary ureteral TCC and in 11% of 63 with renal TCC, after average delays of 28 and 22 months, respectively. Synchronous TCC was found in 2.3% of patients with bladder TCC, 39% of those with ureteral TCC, and 24% of those with renal TCC. Seventeen percent of the subsequent upper-tract lesions would have been demonstrated by intravenous or retrograde urography performed 1 year after the initial onset of primary bladder cancer, and 61% would have been demonstrated by studies performed within 2 years. Therefore, the authors recommend annual radiologic evaluation of the upper urinary tract for 2 years after initial diagnosis and treatment of an upper-tract or bladder TCC.

Carcinoma, Transitional Cell↗
PubMed1987

CT abnormalities in right lower quadrant inflammatory disease: review of findings in 26 adults.

Abnormal abdominal computed tomographic (CT) examinations, performed on 26 adults who presented with clinical evidence of right lower quadrant inflammatory disease, were retrospectively studied. Final diagnoses, established surgically in each case, included complicated appendicitis (15 patients), diverticulitis of the ileum or right colon (4), previously undiagnosed Crohn's disease (3), perforated cecal neoplasm (2), right tuboovarian abscess (1), and paracolic abscess of unknown cause (1). The CT features in each diagnostic group are presented in detail. Solid or ring calcification within a pericecal inflammatory mass was specific for appendicitis, occurring in 40% of the 15 patients. Without calcification, the differentiation of complicated appendicitis from Crohn's disease or diverticulitis, based on CT features alone, may be difficult in some cases.

Adolescent↗
PubMed1986

Low-attenuation thoracic metastases in testicular malignancy.

Low-density abdominal and pelvic lymph nodes are seen in nearly half of patients with testicular cancers. Thoracic low-attenuation metastases are much less common. Three cases of low-density metastases to lung parenchyma and mediastinal nodes are presented. In a man of appropriate age, a low-attenuation pulmonary or mediastinal mass should prompt a search for a primary testicular neoplasm.

Adult↗
PubMed1985

CT demonstration of postanginal sepsis.

A case of postanginal sepsis is presented with a brief discussion of the pathogenesis and presentation of the syndrome. CT scanning can effectively delineate the parapharyngeal inflammatory process, extension along fascial planes, internal jugular vein encroachment and thrombus, as well as septic emboli complications.

Adult↗
PubMedDate not supplied

MR findings in rhinocerebral mucormycosis.

A case of rhinocerebral mucormycosis evaluated by magnetic resonance (MR) imaging is presented, with inflammatory changes in the paranasal sinuses and orbit. Extension of the infection into the cavernous sinus, with cavernous sinus thrombosis and internal carotid artery narrowing, was well demonstrated on pre- and postgadolinium MR images. Infarctions in the anterior choroidal artery distribution suggested intracranial invasion of basal arteries, and watershed distribution infarctions attested to the tenuousness of flow through a narrowed cavernous carotid artery. Magnetic resonance effectively demonstrated the wide array of findings possible in rhinoorbitocerebral mucormycosis.

Adult↗
PubMedDate not supplied

Leptomeningeal metastases: MR evaluation.

Forty patients with positive CSF cytology for subarachnoid dissemination of neoplasms were examined by magnetic resonance (MR) imaging for the detection of intracranial or intraspinal CSF metastases. The MR evidence of cerebral leptomeningeal metastases was noted in 12 of 54 unenhanced (22.2%) and 7 of 20 (35%) gadolinium-enhanced studies. However, in only 2 of the 20 (10%) gadolinium-enhanced scans did the enhanced brain images alone demonstrate the presence of CSF seeding. Four of 29 (13.8%) unenhanced studies of the spine and 6 of 16 (37.5%) gadolinium-enhanced spine studies were positive for neoplastic deposits on the spinal nerves or cord. Magnetic resonance without and with gadolinium enhancement was most likely to be positive in studies of patients with a non-CNS primary malignancy (16/51 = 31.4%) and least accurate with lymphoma or leukemia (1/18 = 5.6%). Although gadolinium administration increases the ability of MR to detect leptomeningeal metastases (particularly in the spine), the overall sensitivity of unenhanced and enhanced MR examinations is low (19.3 and 36.1%, respectively) in patients with proven cytological evidence of neoplastic seeding.

Adolescent↗
PubMedDate not supplied

MR examination for spinal cord compression: impact of a multicoil system on length of study.

Twenty spinal studies to rule out cord compression using a multicoil array system were compared with the 20 consecutive previous studies in which a 5 x 11 inch flat plate coil (5 x 11 FPC) was used on the same 1.5 T MR scanner. The multicoil studies averaged 53 min shorter overall (105 min with the 5 x 11 FPC versus 52 min with multicoil). The reduction in scan time was maximal in studies when Gd-DTPA was administered (76 min reduction) or when the results showed noncompressive epidural disease or intramedullary disease (78 min). Scan quality was diagnostic in all examinations, and lesion localization was superior with the multicoil. The multicoil system substantially reduces scan times when whole spine studies are performed.

Adult↗
PubMedDate not supplied

Proton MR spectroscopy of experimental radiation-induced white matter injury.

We studied the spectroscopic appearance of radiation-induced myelinolysis in cats to understand the characteristics of proton MR spectroscopy of demyelinating disorders. Eight cats received 5,000 rads to a 1.5 x 1.5 cm area of the right cerebral hemisphere. Eight to 9 months after irradiation, a gross area of abnormal postcontrast enhancement and/or high MR signal intensity was detected in the irradiated hemisphere of six of the eight cats. Proton spectra of a 1.0 cm3 voxel in the affected region demonstrated depressed N-acetyl aspartate/creatine-phosphocreatine and N-acetyl aspartate/choline-containing compound peak ratios compared with the contralateral non-irradiated brain in all cats. Elevated amino acid resonances in the 2.0-2.5 ppm range were not consistently seen in irradiated zones of the brain with pathologic findings of demyelination. In vivo proton MR spectroscopy may show differences between irradiated brain and nonirradiated brain even when histopathologic lesions are not apparent yet.

Amino Acids↗