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Biomedical subjects

S L Fritz

Publications and source records attributed to S L Fritz.

At least 19 recordsLinked to original sources
PubMed1982

Three-dimensional computer reconstructions of brain lesions from surface contours provided by computed tomography: a prospectus.

We present a prospectus on the use of computer graphics for the three-dimensional reconstruction and visualization of brain lesions from computed tomographic head examinations, including an algorithm that utilizes surface contour information to reconstruct and display three-dimensional anatomical sites. We provide examples of the use of this algorithm. We offer an algorithm for estimation of the volume and surface area of anatomical sites. The advantages and disadvantages for the clinical use of these algorithms are discussed.

Adenoma, Chromophobe↗
PubMed1982

Direct radiographic magnification: evaluation of three microfocus x-ray tubes.

Three microfocus x-ray tubes (RSI, Siemens, and Eimac) were evaluated for their focal and imaging characteristics. The RSI and Siemens focal spots had similar homogeneous radiation intensity distributions. The Eimac tube had an asymmetric intensity distribution. Because of their focal spot characteristics, the RSI and Siemens tubes provided superior magnification radiographs for small objects. The Siemens and Eimac tubes were preferable for magnification of thick objects because their larger object-film air gap reduced scattered radiation reaching the film.

Humans↗
PubMed1982

Computed tomographic mammography using a conventional body scanner.

The technique for computed tomographic (CT) examination of the breasts using a conventional body scanner is described, and experience with 67 patients is reported. In the diagnosis of both malignant and benign breast lesions, the results with a body scanner were equal to those of a dedicated CT/M mammographic unit. Although the CT study of the breast cannot replace conventional mammography in screening or in routine diagnostic workup, the unique capability of demonstrating both anatomic changes and increased iodide concentration in a cancer provides many advantages over conventional mammography. CT mammography appears to have the capability to detect breast cancers that are occult to other methods. Indications for a CT study of the breasts are: (1) clinically suspected breast cancer, especially with a mammographically occult lesion; (2) questionable mammographic findings, including microcalcifications, tumor shape, architectural distortion, and uncertain lesion location; and (3) evaluation of postbiopsy or postlumpectomy breast cancers when a primary irradiation therapy is contemplated. Breast CT also appears to be a valuable diagnostic tool in searching for a second primary breast cancer, follow-up study of postirradiation of breast cancer, followup study for postmastectomy patients, and screening procedure for genetically high-risk patients, especially those with dense breasts.

Adult↗
PubMed1982

Tomography for evaluation of sacroiliitis.

The radiographs and charts of 18 patients were reviewed to determine if sacroiliac joint tomography clarified the equivocal or clinically inconsistent findings of other imaging procedures. In six of eight patients with proven sacroiliitis, tomography detected joint erosions or sclerosis that were not detected on routine pelvis radiographs. In the other 10 patients, tomography excluded sacroiliitis which had been initially suggested by plain radiographs (four patients), quantitative sacroiliac scintigraphy (three patients), or clinical findings (three patients). The estimated average skin radiation exposure was 1.27 R (0.33 mC/kg) per tomographic section. The authors conclude that tomography improves delineation of sacroiliac joint abnormalities, but its use should be restricted to problem cases because of the high radiation exposure.

Adolescent↗
PubMed1981

Radiographic projections for the diagnosis of arthritis of the hands and wrists.

One hundred consecutive sets of radiographs with the hands halfway supinated (Nørgaard's view) were reviewed retrospectively without knowledge of the clinical diagnosis to determine the value of this view for diagnosis of rheumatoid arthritis. Indistinct cortex at specific sites, reported to be a sensitive indicator of rheumatoid arthritis, was seen in 81% of rheumatoid patients: however, it was not specific for rheumatoid arthritis, being present in both inflammatory and noninflammatory arthritides. These changes are apparently due to variations in cortical morphology and are not true erosions. Definite erosions, which were more specific for inflammatory arthritis, were seen at the same sites; however, erosions could be identified on postero-anterior radiographs in 14 of the 16 cases in which they were seen on the Nørgaard views.

Adolescent↗
PubMed1981

A method for minimizing the radiation exposure from scoliosis radiographs.

The radiation exposure resulting from standard scoliosis radiographs was determined for eighteen adolescent girls. The risk of inducing breast cancer was estimated from the skin-exposure doses. The average skin exposure to the breasts was 59.6 millirads (0.59 mGy) for the anteroposterior radiograph. Assuming a total of twenty-two anteroposterior radiographs during a course of treatment, the cumulative exposure would result in a 1.35% relative increase in the risk of development of breast cancer. By utilizing collimation of the x-ray beam and proper selection of grids, films, and screens, the radiation risk of scoliosis radiographs is minimized.

Adolescent↗
PubMed1981

ROC analysis of diagnostic performance in liver scintigraphy.

Studies on the accuracy of liver scintigraphy for the detection of metastases were assembled from 38 sources in the medical literature. An ROC curve was fitted to the observed values of sensitivity and specificity using an algorithm developed by Ogilvie and Creelman. This ROC curve fitted the data better than average sensitivity and specificity values in each of four subsets of the data. For the subset dealing with Tc-99m sulfur colloid scintigraphy, performed for detection of suspected metastases and containing data on 2800 scans from 17 independent series, it was not possible to reject the hypothesis that interobserver variation was entirely due to the use of different decision thresholds by the reporting clinicians. Thus the ROC curve obtained is a reasonable baseline estimate of the performance potentially achievable in today's clinical setting. Comparison of new reports with these data is possible, but is limited by the small sample sizes in most reported series.

Colloids↗
PubMed1980

Computed tomography in detection and diagnosis of breast cancer.

From October 1, 1976 through July 31, 1979, at the University of Kansas Medical Center, CT/M examinations were performed on 1625 patients. Seventy-eight cancers were histologically diagnosed. A CT/M study using our contrast medium enhancement technique yields both static anatomical changes and dynamic measurements of abnormal iodide concentrations in the breast cancers. This unique ability of CT/M provides many advantages as compared with conventional mammography in the diagnosis of breast cancer. The detection rate in 78 cancers by CT/M was 94% and 77% for the mammography. The CT/M appears to be specially superior to the mammography for detecting cancers in dense, premenopausal dysplastic breasts. The CT/M can detect totally unsuspected very small breast cancers that were unable to be identified by conventional mammography or physical examinations. The CT/M scan also seems to be a better test for recognizing precancerous high risk lesions. CT/M evaluation affords definitive diagnostic help in instances where the mammographic and/or physical examinations are inconclusive. Although CT/M will not replace conventional mammography in routine breast examinations, it overcomes the limitation of mammography.

Breast↗
PubMed1980

Use of a gradient intensifying screen for scoliosis radiography.

A gradient intensifying screen composed of rare earth phosphors and calcium tungstate was developed. It provides uniform film density when there is a graded increase in subject density. Use of this screen for scoliosis radiography provides an improved image and reduces radiation exposure.

Absorptiometry, Photon↗
PubMed1980

A radiographic method for three-dimensional analysis of spinal configuration.

Current two-dimensional methods for quantifying scoliosis are inadequate. A radiographic method has been developed which determines the three-dimensional location and rotation of each vertebra. Posteroanterior and posterior oblique radiographs of the spine are obtained with the patient standing within a reference frame. Computerized analysis of these radiographs provides a complete quantitative description of spinal configuration. Using this information, scoliosis progression may be more accurately predicted, and therapeutic measures can be more thoroughly analyzed utilizing biomechanical principles.

Computers↗