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Biomedical subjects

S N Wiener

Publications and source records attributed to S N Wiener.

At least 19 recordsLinked to original sources
PubMed1991

Magnetic resonance imaging features of fractures using the short tau inversion recovery (STIR) sequence: correlation with radiographic findings.

The MRI characteristics of fractures have been described on the basis of spin echo (SE) images emphasizing T1 and T2 contrast. These previous studies were carried out for injuries in which radiographic proof was often lacking. In comparison with SE images, short tau inversion recovery (STIR) images have been shown to provide superior contrast between normal and abnormal marrow. To determine the MRI characteristics of fracture using STIR pulse sequences, we reviewed 28 patients who had radiographic evidence of fracture and were examined with T1-weighted SE and STIR sequences. MRI marrow signal abnormalities were demonstrated at all fracture sites ranging in age from less than 24 h to 8 weeks. The extent of marrow signal abnormalities exceeded the size of corresponding radiographic findings of fracture in all cases. The MRI features of fractures on T1-weighted SE images consisted of irregular intramedullary zones of hypointensity. On STIR images a corresponding zone of hyperintensity extended to the outer cortical margin. Intramedullary lines of hypointensity extending to the inner cortical margin were identified within the hyperintense marrow abnormality on STIR images in 64% of the fractures. The results of this study show that MRI using T1-weighted SE and STIR sequences can consistently demonstrate prominent signal abnormalities at fracture sites including those in which radiographic signs are subtle.

Adult↗
PubMed1991

Diagnosis of hematogenous pyogenic vertebral osteomyelitis by magnetic resonance imaging.

The clinical information and imaging data from 27 patients with hematogenous pyogenic vertebral osteomyelitis were reviewed. All patients had roentgenographic and magnetic resonance imaging examinations. Seventeen patients had computed tomograms; 17 had technetium Tc 99m medronate bone scans; and seven had gallium citrate Ga 67 scans. Magnetic resonance imaging, when used as a part of the initial radiologic evaluation, detected abnormalities consistent with osteomyelitis in all 27 patients. Magnetic resonance imaging also demonstrated paravertebral and/or epidural extension of infection in 14 patients, including seven patients who had neurologic signs of lower-extremity weakness. Roentgenograms, computed tomograms, technetium bone scans, and gallium scans had findings suggestive of the diagnosis in 48%, 65%, 71%, and 86% of the patients, respectively. We recommend magnetic resonance imaging as an important and perhaps critical imaging modality for detection of pyogenic vertebral osteomyelitis.

Evaluation Studies as Topic↗
PubMed1989

Treatment of Morton's neuroma using percutaneous electrocoagulation.

A new modality for treating Morton's neuroma was introduced and performed by the authors, using a nerve lesion generator. Seventy-nine lesions were evaluated by obtaining the patients' responses to three questions. By rating their symptoms on a 0-5 scale both before and after the neurectomy, the patients showed a 56% reduction in symptoms. With a gone-improved-same-worse rating, the patients responded with 25%, 46%, 24%, and 5% in each respective category. The overall assessment of the procedure by the patients yielded 68% pleased and 32% not pleased. An average of 4 hr was missed from work following the neurectomy, and only 20% of the patients required mild analgesics.

Adult↗
PubMed1986

Magnetic resonance imaging in patients with diplopia. A review.

Magnetic resonance imaging may be the procedure of choice for evaluating patients with diplopia; the absence of signals from cortical bone enables the brain stem and individual cranial nerves to be visualized and the imaging planes selected easily, and there is excellent contrast resolution of pathologic lesions. A clinical assessment of diplopia including the identification of associated neurologic disturbances is necessary prior to MR imaging, however, to assure that appropriate anatomic areas are studied and imaging sessions kept within acceptable time limits. The relevant physiology and anatomy critical to normal ocular motility are reviewed and the value of MR imaging for diplopia demonstrated by selected patient examples.

Adult↗
PubMed1984

A strategy for magnetic resonance imaging of the head: results of a semi-empirical model. Part I.

This paper is an introduction to lesion detection problems of MR. A mathematical model previously developed for normal anatomy has been extended to predict the appearance of any hypothetical lesion in magnetic resonance (MR) images of the head. The model is applied to selected clinical images to demonstrate the loss of lesion visibility attributable to "crossover" and "boundary effect". The model is also used to explain the origins of these problems, and to demonstrate that appropriate gray-scale manipulations can remedy these problems. Specifically, pulse sequences that cause lesions to be the brightest tissue in the image are shown to eliminate the problems of crossover and boundary effect.

Brain Diseases↗
PubMed1984

A strategy for magnetic resonance imaging of the head: results of a semi-empirical model. Part II.

A semi-empirical model was used to identify specific pulse sequences that cause most lesions to appear distinctly brighter than normal tissues in magnetic resonance (MR) images of the head. Clinical trials confirm the utility of these sequences for patient screening. As a result, a strategy for effective and efficient MR imaging of the head is proposed. The previously described gray-scale model has been modified to account for the effect of image noise. By means of computer simulation, 13,800 different hypothetical cerebral lesions were imaged with a variety of pulse sequences. A number of conclusions resulted. First, two sequences are expected to be sufficient to visualize most intracranial lesions, a "diagonal" SE sequence (e.g., SE 2500/80) and an IR sequence with a short inversion time (e.g., IR 1800/200). These sequences are orthogonal, i.e., lesions missed by one are likely to be detected by the other. Second, signal averaging the screening sequences is expected to be more effective than optimized sequences when lesion tissue parameters differ little from brain. Finally, the effectiveness of unaveraged screening sequences suggests that improved signal-to-noise ratio (SNR) is not necessary for the detection of most large lesions. Therefore, the increased SNR achievable through signal averaging or increased field strength might best be utilized to improve spatial resolution so that smaller lesions can be detected.

Brain Diseases↗
PubMed1983

Nuclear magnetic resonance: a gray scale model for head images.

The gray scale of nuclear magnetic resonance (NMR) head images is explained in terms of tissue and machine parameters. Tissue parameters considered here include the spin-lattice relaxation time, the spin-spin relaxation time, and the proton density. Machine parameters include the pulse sequence (saturation recovery, inversion recovery, or spin echo), the repetition time, and the delay time. The ability of the operator to alter the NMR gray scale predictably is examined by computer simulation. The simulation computes NMR pixel values for a selected combination of tissue and machine parameters. The computed values are compared with those extracted from clinical NMR images. The agreement between simulation and clinical pixel values implies that the operator can use the machine parameters to alter the NMR gray scale, and thereby control contrast, appropriate to the diagnostic requirements. The extent to which the NMR gray scale can be predictably controlled is illustrated through graphs, simulated contrast displays, and representative NMR images.

Brain Chemistry↗
PubMed1979

67Ga-citrate uptake by the parotid glands in sarcoidosis.

Bilateral accumulation of 67Ga-citrate by the parotid glands was observed in 9 of 27 patients (33%) with sarcoidosis and in a subgroup of 12 with systemic symptoms such as fever or clinically acute, progressive disease (75%). Asymptomatic patients or those with probable sarcoidosis associated with hilar and/or paratracheal adenopathy will not have parotid uptake. Similarly, uptake seldom occurs in normal patients or in those with untreated lymphoma or Hodgkin disease. If other inflammatory or granulomatous processes such as tuberculosis can be excluded, and if there is no history of head and neck irradiation, then this finding in acutely ill patients suggests sarcoidosis.

Citrates↗
PubMed1979

Scintigraphy and ultrasonograhy of hepatic hemangioma.

The clinical findings, radionuclide scintigrams, and ultrasonograms of hepatic hemangiomas are described for 11 patients. Scintigraphy frequently demonstrated a marginal or subcapsular location. The lesions were otherwise nonspecific in appearance and were indistinguishable from metastatic foci. Sonographically, hypoechoic, hyperechoic, and predominantly anechoic patterns were observed, not unlike those described for malignant foci. However, 7 hemangiomas had a central linear septum. Liver function tests were normal in all patients. Since percutaneous biopsy is hazardous and hepatic angiography usually diagnostic, the scintigraphic and ultrasonic appearances described may help in the selection of the appropriate investigative studies.

Hemangioma↗
PubMed1979

The accuracy of sonography in the differential diagnosis of obstructive jaundice: a comparison with cholangiography.

The value of sonography in determining the site and nature of biliary obstruction with surgical jaundice is described in 32 patients. All diagnoses were subsequently established by surgery and pathology. The site of obstruction was delineated in 94%, while the nature of the lesion was established in 81%. In comparison, contrast cholangiography correctly delineated the site in 96%, but helped determine the etiology in only 82%. Sonography is sufficient to adequately evaluate patients prior to surgery, while percutaneous transhepatic cholangiography should probably be used only when satisfactory ultrasound examinations cannot be obtained.

Aged↗
PubMed1978

An assessment of routine liver scanning in patients with breast cancer.

A retrospective review of the value of routine perioperative liver scanning for patients with breast cancer was performed. The liver was considered to be normal in 231 of 234 patients. The hepatoscan uncovered only one patient with unsuspected metastases. There were eight false-positive studies. Measurements of liver function, SGOT, SGPT, alkaline phosphatase, and bilirubin levels separated true positive from false-positive hepatoscans for all except one patient. Abnormal liver chemistry studies also identified liver metastases in an additional follow-up group of 192 patients. The low yield of detection of hepatic metastases during the initial work-up of breast cancer patients suggests that routine hepatoscanning be abandoned unless there is evidence of abnormal liver function.

Breast Neoplasms↗