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Biomedical subjects

R R Price

Publications and source records attributed to R R Price.

At least 73 records · Page 4Linked to original sources
PubMed1983

Digital subtraction angiography: limitations for the detection of pulmonary embolism.

Perfusion lung scanning, magnification pulmonary arteriography, and digital subtraction angiography (DSA) were performed prior to and following Gelfoam embolization of selected pulmonary arteries in eight canines. The sites of embolization were identified in 75% of perfusion lung scans, in 93% of magnification pulmonary arteriograms, in 75% of arterial phase DSA studies, and 100% of parenchymal phase DSA examinations. With technological advances, DSA has the potential to become the examination of choice for the evaluation of patients suspected of having pulmonary emboli.

Angiography↗
PubMed1983

Iohexol for excretory urography: a comparative study.

A new iodinated nonionic contrast agent (Iohexol) was compared to an ionic contrast agent (renografin 60) in a double-blind study. Fifty-five patients with normal renal function were studied for incidence of undesirable side-effects and quality of the resultant excretory urogram. No major adverse reactions occurred. Minor side-effects due to the contrast occurred more than two times as often with Renografin than when Iohexol was used. The quality of visualization of the collecting system on urography was considered excellent in 44% of the patients receiving Iohexol as compared to a 17% frequency when Renografin was used.

Adolescent↗
PubMed1983

Radiation absorbed doses from iron-52, iron-55, and iron-59 used to study ferrokinetics.

Biological data obtained principally with Fe-59 citrate are used with physical data to calculate radiation absorbed doses for ionic or weak chelate forms of Fe-52, Fe-55, and Fe-59, administered by intravenous injection. Doses are calculated for normal subjects, primary hemochromatosis (also called idiopathic or hereditary hemochromatosis), pernicious anemia in relapse, iron-deficiency anemia, and polycythemia vera. The Fe-52 doses include the dose from the Mn-52m daughter generated after injection of Fe-52. Special attention has been given to the dose to the spleen, which has a relatively high concentration of RBCs and therefore of radioiron, and which varies significantly in size in both health and disease.

Computers↗
PubMed1983

Studies of blood flow employing duplex, pulsed Doppler real-time sonography.

The physics of pulsed Doppler techniques have been recently applied to clinical evaluation of superficial blood vessels and the flow within them. Essential physical principles of pulsed Doppler ultrasound are presented, including spectrum analysis and flow measurements. Duplex instrumentation combining high-resolution real-time imaging and a pulsed-Doppler system is described. Indications for duplex carotid sonography are outlined. Clinical applications are discussed and examples of normal and pathologic states are shown. Finally, the role of duplex sonography in the evaluation of carotid vascular disease is compared to traditional arteriographic and contemporary digital subtraction angiographic methods.

Blood Flow Velocity↗
PubMed1982

Simultaneous bi-plane digital video-fluoroscopy.

A prototype system for digital subtraction angiography that is capable of acquiring digitized video-fluoroscopic images simultaneously from both anterior and lateral imaging chains of a conventional bi-plane system was developed. A hardware module that takes images from both the anterior and lateral video cameras and displays them both on a single video image prior to digitization was designed and constructed. The three-dimensional information provided by a digital bi-plane images should improve the accuracy of cardiac-ventricular function studies. In addition, bi-plane imaging should reduce the need for additional views and the associated repeated injections of contrast media. With this technique, digital bi-plane imaging can be carried out with commercially available systems without duplication of the digital-processing chain.

Animals↗
PubMed1982

Evaluation of digital venous angiography for the diagnosis of renovascular hypertension.

Thirty-two patients being evaluated for hypertension by angiography were also studied by digital video subtraction angiography (DVSA). Twenty-three of the 76 renal arteries were found by conventional angiography to have significant lesions. Two experienced angiographers evaluated the DVSA studies without knowledge of the angiographic results. The accuracy of DVSA for evaluation of renal arteries was 87% for Observer I and 80% for Observer II. Sensitivities were 87% and 83% and specificities 87% and 79% for the two observers. Of the 13 patients with significant lesions, Observer I identified at lest one lesion in all 13 while Observer II identified a lesion in 12 of the 13. The high false-positive rate (26% for Observer I and 37% for Observer II) was thought to be caused by subtraction artifacts, quantum noise, relatively low spatial resolution, and the Mach effect.

Angiography↗
PubMed1982

Work in progress: ultrasonic texture of normal rat liver tissue using a standardized in vivo measurement.

A prototype computer-augmented diagnostic ultrasound system was used in an investigation of the range of echo amplitudes obtained from measurements of normal exteriorized rat livers. A secondary goal was to develop a method for minimizing variations in measurement techniques and instrument stability. The average echo amplitude was obtained from a user-selected homogeneous region of the liver on a B-mode scan image. A similar B-mode scan of a commercially available liver tissue equivalent phantom was also obtained immediately after each rat liver measurement and was used as a calibration scan. A normalization factor developed from the calibration scan was used to correct all in vivo measurements for system variation. The average echo amplitude from the livers of a group of normal rats, when corrected by the calibration scan, exhibited a narrow range of values with a coefficient of variation of only 5%. The development of a technique that yields a narrow range of values for normal tissues should encourage further investigation of tissue characterization methods.

Animals↗
PubMed1982

The effects of gating delays on ejection estimates: concise communication.

We have examined the effects of gating delays on the left-ventricular ejection fraction as measured by gated blood-pool studies. Patients with normal ventricular function were shown to have greater errors introduced by gate delays than those with poor function. The magnitude of the error depends on the shape of the ventricular time-activity curve. Actual delay measurements were performed on several commercial gates.

Cardiac Output↗
PubMed1981

The potential impact of digital radiography (DR) on the speciality of nuclear medicine.

Digital radiography is a reasonably economical system that helps diagnostic imaging physicians to develop increasingly less-invasive procedures, obtain maximal information at a given dose and increase the flexibility and convenience involved with diagnostic workups. The range of applications of DR has not been fully established at this time. Comparison of its properties with those of conventional nuclear medicine may suggest areas of potential application. Compared to nuclear medicine techniques, DR in general provides improved anatomical resolution, improved contrast resolution, sometimes equivalent functional information, and decreased imaging time. On the other hand, some functional nuclear medicine studies provide information not available by DR; including the gallium scan, bone scan, hepatic-biliary scan, and lung scan. Therefore, nuclear medicine procedures will be complimentary in some instances to digital radiography procedures and competitive in others. The proper roles of each modality in various clinical settings await future detailed and comprehensive efficacy studies.

Animals↗
PubMed1980

Nuclear magnetic resonance and computed tomography: comparison of normal human body images.

Normal human body images of the thorax and abdomen were obtained using nuclear magnetic resonance (NMR) and computed tomography. Correlation of the images allowed precise anatomic identification of organs and structures. Differences between the images appear to be significant. NMR has potential as a methodology for assessing and imaging nuclear composition. Certain clinical implications from this technique are discussed.

Humans↗
PubMed1979

Scintigraphic characteristics of experimental myocardial infarct extension.

Technetium-99m-stannous pyrophosphate scintiphotos were evaluated for diagnosing and quantitating myocardial infarct (MI) extension in sedated dogs. Infarction and extension were produced by serial left anterior descending coronary artery ligations at 0 and 48 hours. We compared serial scintiphoto data with regional myocardial blood flow (MBF) (microsphere technique) and infarct histopathology. In eight control dogs, the scintigraphic MI area was stable at 24, 48, and 72 hours. In each of 11 dogs undergoing extension, the MI area increased after the 48-hour occlusion, averaging a 48.9% increase (p less than 0.001). Grossly, most extensions were mixtures of confluent necrosis and moderate (patchy) necrosis. MBF to confluent infarct tissue decreased significantly, allowing the documentation of extension by totaling the grams of newly flow-deprived tissue, but patchy infarct tissue had little flow deprivation, making it difficult to quantitate this type of extension accurately by flow criteria alone. Rarely, extension could be diagnosed using conventional histologic criteria. We concluded that the scintiphoto MI area was related quantitatively to infarct weight in both control and extension. However, it was not possible to determine that an increase in the MI scintiphoto area was an accurate predictor of the degree of extension using independent flow or pathologic criteria.

Acute Disease↗