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Biomedical subjects

D B Downey

Publications and source records attributed to D B Downey.

At least 37 records · Page 2Linked to original sources
PubMed1996

Accuracy of prostate volume measurements in vitro using three-dimensional ultrasound.

RATIONALE AND OBJECTIVES: We assessed the ability of a three-dimensional (3D) ultrasound imaging system to measure accurately prostate volume. METHODS: Multiple two-dimensional ultrasound images of cadaver prostates scanned in a water bath were reconstructed into three-dimensional (3D) images. The volumes of the prostates were calculated from these 3D images and compared with the actual volumes. Multiple 3D ultrasound volume readings were evaluated for precision. RESULTS: The slope of the best-fit line correlating 3D ultrasound estimated volume and true volume was 1.006 +/- 0.007. The average error was 0.36 +/- 1.17 cm3; the coefficient of determination (r2), which is the measure of the straight-line relationship, was .9997; and the standard error was 1.15 cm3. CONCLUSION: Three-dimensional ultrasound images accurately reflect true prostate volumes measured in vitro.

Cadaver↗
PubMed1996

Three-dimensional ultrasound imaging of the eye.

We assessed whether an inexpensive, three-dimensional (3D) ultrasound (US) imaging system could produce clinically useful 3D images, without causing patient discomfort. Five patients were examined. The 3D US system consisted of a transducer holder containing a mechanical motor, and a microcomputer. During data acquisition the transducer was mechanically rotated for 22 seconds, while 200 two-dimensional (2D) US images were collected and formed into a 3D image by the computer. The 3D image was viewed on the computer monitor. The 3D images correlated with the clinical and radiological findings. The new perspectives were helpful in diagnosing eye abnormalities and no patient discomfort occurred. The device was easy to use. It is concluded that, as good-quality 3D and 2D US images were produced quickly, with no patient discomfort, and the device is inexpensive, uncomplicated, and easily attached to existing ultrasound machines, it will probably be useful in clinical practice.

Adult↗
PubMed1996

Three-dimensional prostate ultrasound and its application to cryosurgery.

Transrectal ultrasound (TRUS), despite its undeniable utility in prostate imaging, employs a spatially flexible and variable 2-dimensional (2-D) imaging technique to visualize a 3-dimensional (3-D) disease process and anatomy. To circumvent some of the limitations of 2-D TRUS, 3-D TRUS was developed. The system consists of a motorized assembly (to hold a standard ultrasound transducer) and a computer with a video frame grabber. The microcomputer, using software developed in our laboratory, rapidly reconstructs a series of linear ultrasound images into a 3-D image. The 3-D TRUS technology has been incorporated into our program for cryoablation of the prostate. With intraoperative 3-D TRUS providing a unique coronal view, cryoprobe placement is facilitated to detect malalignment and avoid subsequent suboptimal cryoablation. In our use of 3-D TRUS guidance, in all 21 initial patients, probe malalignment, otherwise not apparent on standard 2-D TRUS, was detected and corrected before cryosurgery. With median follow-up of just < 1 year, only 2 of 44 biopsy cores (from the same site of 1 patient) were positive at 3 and 6 months. 3-D TRUS appears to be a valuable adjunctive tool in prostate imaging, especially in providing guidance for cryoblation of prostate cancer.

Cryosurgery↗
PubMed1994

Poster production by color laser imager.

The scientific poster is an important educational tool at most radiology meetings. The visual impact of the exhibit is important in attracting attention and conveying content to the reader. A new method of designing and producing full-color transilluminated posters in the radiology department using a personal computer and color laser imager is described. The advantages of this approach are author control over the production process and production of a visually interesting exhibit.

Audiovisual Aids↗
PubMed1994

Findings of magnetic resonance and colour-flow Doppler imaging of orbital embryonal rhabdomyosarcoma.

The authors describe a case of embryonal rhabdomyosarcoma of the orbit evaluated with magnetic resonance imaging (MRI) and colour-flow Doppler imaging. MRI demonstrated a markedly enhancing tumour with no discrete vessels. Colour-flow Doppler ultrasonography showed evidence of perfusion; however, discrete vascular channels were difficult to visualize, and no evidence of large vessels within the tumour was found at surgery. The differential diagnosis of this condition is discussed, as well as the potential role of colour-flow Doppler imaging in the assessment of orbital tumours, a role in which this method has not yet been widely applied.

Child, Preschool↗
PubMed1993

Producing picture-perfect posters.

Scientific posters form an integral part of many radiology meetings. They provide the opportunity for interested parties to read the material at an individualized pace, to study the images in detail, and to return to the exhibit numerous times. Although the content of the poster is undoubtedly its most important component, the visual presentation of the material can enhance or detract from the clarity of the message. With the wide availability of sophisticated computer programs for desktop publishing (DTP), one can now create the poster on a computer monitor with full control of the form as well as the content. This process will result in a professional-appearing poster, yet still allow the author the opportunity to make innumerable revisions, as the poster is visualized in detail on the computer monitor before printing. Furthermore, this process is less expensive than the traditional method of typesetting individual sections separately and mounting them on cardboard for display. The purpose of this article is to present our approach to poster production using commercially available DTP computer programs.

Computer Graphics↗
PubMed1993

Three-dimensional sonographic reconstruction: techniques and diagnostic applications.

In this review, we summarize the techniques of obtaining and reconstructing three-dimensional (3D) sonograms in a number of anatomic areas, catalog the clinical efforts at 3D sonography so far, and introduce more recent work in this area that takes advantage of the unique features of sonography. Although it is an active area of 3D imaging research, cardiac 3D imaging is not discussed because it has unique requirements stemming from the heart's anatomic inaccessibility and motion. Image analysis and display also are not covered, as no clear consensus has been reached about the usefulness of the large number of available methods.

Female↗
PubMed1993

Ultrasonographically guided biopsy of small intra-abdominal masses.

Ultrasonography (US) has traditionally been considered inferior to computed tomography (CT) for guidance in fine-needle aspiration biopsy (FNAB) of small intra-abdominal masses. To assess the validity of this view, the results obtained for 58 consecutive patients referred for US-guided FNAB of intra-abdominal masses of diameter 25 mm or less were retrospectively analysed. In each case two to four (usually three) aspirations were initially performed with a 22-gauge needle; sufficient tissue for diagnosis was obtained in 53 of the 58 cases (91%). The procedure had to be repeated in the other five patients to acquire diagnostic tissue. Apart from some minor abdominal pain, no complications were encountered. Proof of the cytologic diagnosis was available for 49 of the 58 patients (84%)--from histologic examination in 22 cases and from the appropriate clinical and radiologic course in 27. A sensitivity of 95% and a specificity of 90% for the technique were found for the patients for whom adequate follow-up information was available. The authors conclude that FNAB of intra-abdominal masses measuring 25 mm or less can be accurately and safely performed under US guidance.

Abdominal Neoplasms↗
PubMed1993

Sonolucent peripancreatic masses: differential diagnosis and related imaging.

The most common cause of a sonolucent mass in the epigastrium is a pancreatic pseudocyst; however, several other conditions can simulate a pseudocyst on ultrasonography (US) scans. This pictorial essay illustrates the spectrum of conditions that may present in this fashion and demonstrates the use of other imaging modalities, such as colour-flow and pulsed Doppler US, computed tomography, magnetic resonance imaging and angiography, in their evaluation.

Abscess↗
PubMed1992

CT findings in patients with small-bowel transplants.

Orthotopic small-bowel transplantation procedures are being performed increasingly often worldwide. CT plays an important role in both the preoperative assessment and the postoperative care of these patients. This pictorial essay serves to acquaint radiologists with the CT findings related to small-bowel transplantation.

Abscess↗
PubMed1992

Peripancreatic fluid collections: vascular structures masquerading as pseudocysts.

Five patients with splanchnic arterial aneurysms and one patient with a tortuous splenic vessel presented with peripancreatic masses that exhibited an anechoic portion in real-time ultrasonography (US) images; the masses were incorrectly diagnosed as pseudocysts. In two patients a vascular abnormality was suspected, and colour-flow Doppler and pulsed Doppler US were performed; these techniques showed the presence of pseudoaneurysms. In the other four patients the possibility of a pseudoaneurysm was not entertained until further studies had been performed. These results emphasize the need for colour-duplex US evaluation of all peripancreatic fluid collections during the initial US examination to avoid the misinterpretation of an aneurysm or a pseudoaneurysm as a simple or complex fluid collection and to prevent the potential disaster of performing biopsy, surgery or other interventions.

Adult↗
PubMed1991

Pseudomembranous colitis: sonographic features.

The sonographic features of pseudomembranous colitis (PMC) are described in 13 patients and correlated with clinical, radiologic, and pathologic findings. At sonography, the wall of the entire colon was moderately to markedly thickened in all patients. The enlarged colon wall was most commonly shown as a wide band of heterogeneous medium echogenicity surrounded by a narrow hypoechoic layer. Pathologic correlations proved that the wide inner stratum represented severely edematous submucosa and mucosa, while the outer layer depicted the muscularis propria. Almost complete effacement of the lumen of the colon occurred secondary to the mural edema in 69% of the cases. The dearth of intraluminal gas combined with thickening of the colon wall and ascites facilitated excellent sonographic evaluation. The diagnosis of PMC is strongly suggested by the presence of these sonographic features in a patient with watery diarrhea and a history of antibiotic therapy.

Adult↗