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Biomedical subjects

W R Brody

Publications and source records attributed to W R Brody.

At least 19 recordsLinked to original sources
PubMed1997

Segmentation algorithms for detecting microcalcifications in mammograms.

The presence of microcalcification clusters in mammograms contributes evidence for the diagnosis of early stages of breast cancer. In many cases, microcalcifications are subtle and their detection can benefit from an automated system serving as a diagnostic aid. The potential contribution of such a system may become more significant as the number of mammograms screened increases to levels that challenge the capacity of radiology clinics. Many techniques for detecting microcalcifications start with a segmentation algorithm that indicates all candidate structures for the subsequent phases. Most algorithms used to segment microcalcifications have aspects that might raise operational difficulties, such as thresholds or windows that must be selected, or parametric models of the data. We present a new segmentation algorithm and compare it to two other algorithms: the multi-tolerance region growing algorithm that operates without the aspects mentioned above, and the active contour model that has not been applied previously to segment microcalcifications. The new algorithm operates without threshold or window selection, or parametric data models, and it is more than an order of magnitude faster than the other two.

Algorithms↗
PubMed1991

Pathways to improved radiologic research. An NIH workshop.

In summary, the workshop recommended two years of research training as being essential for radiologists to acquire the skills and knowledge necessary to begin a successful research career in today's funding and academic environment. Many pathways can combine two years of research training and provide fulfillment of existing requirements to achieve specialty certification and subspecialty credentialing. Departments of radiology supporting the beginning qualified investigator should allow him or her approximately 75% research time for the first three years of the academic appointment. Departmental research time accorded faculty members may best be concentrated on a few individuals, providing them sufficient time to be competitive for peer-reviewed grants and enabling research advances to provide a solid foundation for the future of radiologic imaging.

Humans↗
PubMed1986

Carotid bifurcation: results of spliced hybrid subtraction angiography compared with standard temporal and hybrid images.

Hybrid subtraction angiography can provide a higher percentage of two-view examinations of the carotid bifurcation. Unfortunately, hybrid images are lower in signal-to-noise ratio (S/N) than temporal subtraction angiographic images and are often described as "noisy." The present study was designed to determine if the lower S/N of hybrid subtraction angiography could be restricted to the contralateral carotid bifurcation by "splicing" a small hybrid region of interest into a larger temporal image. Twenty-two selected images were examined on four image quality scales by seven readers. Similarity of reader scoring was characterized by cluster analysis and was good. Ipsilateral carotid arteries were preferred as temporal images, and contralateral carotid arteries were preferred as hybrid images. The splice image was preferred over both. The splice image retained the superiority of temporal subtraction angiography in the region of the ipsilateral carotid artery and incorporated the superiority of hybrid subtraction angiography in the region of the contralateral carotid artery. The splice image incorporated the best features of both image modalities.

Aged↗
PubMed1985

Digital processing of film radiographs.

Initial clinical experience with a system for the digitization, processing, and display of film radiographs is described. Film is digitized using a high-intensity laser scanner; the recorded image data may then be subjected to a wide variety of processing options, with display of processed images on television monitors. The possibilities of clinical applications to processing and display of chest radiographs and film mammograms are described. A comparison of conventional analog subtraction and digitized film subtraction angiography indicated equivalent diagnostic capability, with the advantage of flexible, interactive image processing with the digital technique. A specially designed, energy-selective cassette permits dual-energy imaging from two films effectively exposed to different x-ray energy spectra. Dual-energy imaging may be capable of the characterization of body materials, including lung nodules, and useful for eliminating obscuring radiographic shadows overlying regions of interest.

Angiography↗
PubMed1984

Effect of volume and rate of contrast medium injection on intravenous digital subtraction angiographic contrast medium curves.

The image quality of temporal (mask mode) intravenous digital subtraction angiography is directly dependent on the shape of arterial time-concentration curves produced by the intravenous injection of contrast medium. Curves that are narrow and tall minimize motion artifact (misregistration) and maximize contrast enhancement (pre- and postcontrast differences). To determine the effects of rate and volume of injection of contrast medium on intravenous digital subtraction angiographic curves, ioxaglate (Hexabrix), a monoacidic ionic dimer, was injected into large mongrel dogs. Quantitative measurements of opacification were made over time in the femoral arteries using a modified General Electric CT/T scanner. Peak opacification was directly proportional to the volume of contrast medium injected. Curve width was not affected by increasing volume of injection. At rates below a critical point, slower injection rates produced progressively shorter and wider arterial time-concentration curves. Above that critical point, increasing the rate of injection did not affect either curve width or curve peak.

Angiography↗
PubMed1984

A high frame-rate digital subtraction angiography imaging technique for evaluation of aortofemoral runoff.

Intravenous digital subtraction angiography was used to obtain a complete aortofemoral runoff examination of high diagnostic quality in a single patient session in eight patients. Using a 9-inch (22.9-cm) image intensifier, oblique and posteroanterior projections were obtained from the level of the aortic bifurcation to the tibial artery trifurcation. This technique is based upon the administration of one-half of the usual dose of contrast agent combined with a high frame-rate imaging technique and postacquisition integration to increase the signal-to-noise ratio. It is easily performed on an outpatient basis, lowers patient risk, and allows a significant savings of time, film, and cost compared with the conventional intra-arterial aortofemoral runoff examination.

Aortography↗
PubMed1984

Hybrid intravenous digital subtraction angiography of the carotid bifurcation.

A hybrid digital subtraction angiography technique and noise-reduction algorithm were used to evaluate the carotid bifurcation. Temporal, hybrid, and reduced-noise hybrid images were obtained in right and left anterior oblique projections, and both single- and multiple-frame images were created with each method. The resulting images were graded on a scale of 1 to 5 by three experienced neuroradiologists. Temporal images were preferred over hybrid images (average score = 3.2 and 2.4, respectively). The percentage of nondiagnostic examinations, as agreed upon by two readers, was higher for temporal alone than temporal + hybrid (4 and 1, respectively). In addition, also by agreement between two readers, temporal + hybrid images significantly increased the number of bifurcations seen in two views (87%) compared to temporal subtraction alone (64%).

Aged↗
PubMed1983

Clinical application of hybrid subtraction digital angiography: preliminary results.

The clinical application of hybrid subtraction in digital fluoroscopy of the vasculature is reported in our first 30 patients studied. Hybrid subtraction combines the advantages of temporal and dual energy subtraction techniques to achieve simultaneous elimination of overlying bone, soft tissue, and motion induced artifacts. Hybrid subtraction improved the subjective appearance of an image in 19 of 30 (63%) studies but additional diagnostic information was only revealed in 11 of 30 (37%) patients.

Angiography↗