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Biomedical subjects

S R Bunker

Publications and source records attributed to S R Bunker.

At least 19 recordsLinked to original sources
PubMed1990

Pixel overflow artifacts in SPECT evaluation of the skeleton.

The successful application of single photon emission computed tomography (SPECT) techniques to radionuclide evaluation of the skeleton depends on strict quality control measures, recognition of potential artifacts, and the selection of appropriate cases for specific reprocessing techniques. The application of simple image-processing routines to problems of "hot spot" and bladder pixel overflows facilitated a reduction in the technical inadequacy rate from 19% to 2% for SPECT evaluation of 100 hips, as well as improvement in diagnostic image quality in a variety of additional cases.

Adult↗
PubMed1986

Left ventricular performance of the athletic heart during upright exercise: a heart rate-controlled study.

This study compares the left ventricular performance of chronically conditioned pentathletes (N = 10) with less-conditioned subjects (N = 10) during dynamic upright exercise. The pentathletes were found to have a superior treadmill performance [24 +/- 4 vs 17 +/- 2 min (SD), P less than 0.01], reduced resting heart rate (41 +/- 13 vs 62 +/- 6 bpm, P less than 0.01), and increased left ventricular mass (254 +/- 85 vs 179 +/- 35 g, P less than 0.05) compared to the control group. Radionuclide ventriculography and heart rate controlled-bicycle ergometry were employed to examine changes in left ventricular ejection fraction, end-diastolic volume, end-systolic volume, and stroke volume. Heart rate was controlled by adjusting the resistance of the ergometer until stable heart rates of 90, 110, 130, and 150 bpm were achieved. Following heart rate stabilization, 99mTc images were acquired during 3-min stages at each target heart rate level. In the pentathletes, left ventricular ejection fraction, end-diastolic volume, and stroke volume increased (P less than 0.01) during exercise, and end-systolic volume tended to decrease. No difference was noted in left ventricular ejection fraction between groups when heart rates were matched. However, the exercise-induced changes in end-diastolic volume and stroke volume were greater (P less than 0.01) in the pentathletes. In conclusion, the athletes studied relied on the same mechanism as the less-conditioned subjects for improving pump performance during exercise stress, but the athletes' ability to mobilize a greater end-diastolic volume accounts for their larger stroke output during each stage of heart rate-matched exercise.

Adult↗
PubMed1985

Unilateral renal agenesis and other causes of the solitary photopenic renal fossa.

The differential diagnosis of a solitary photopenic defect in the renal fossa observed at renal scintigraphy is extensive. A case of one of the most unusual causes for this finding, renal agenesis, is presented. Additional cases that illustrate the similarity in the radionuclide appearance of other pathologic entities are also presented. Correlation with clinical findings and other imaging modalities is required to accurately distinguish these conditions.

Carcinoma, Renal Cell↗
PubMed1985

Scintigraphic appearance of the piriformis muscle syndrome.

This is the first report in the nuclear medicine literature of the scintigraphic appearance of the piriformis muscle syndrome. This syndrome previously has been thought to be a purely clinical diagnosis and imaging modalities have been ignored. However, its confusing clinical presentation can lead to unnecessary surgical exploration. This case is presented to illustrate the characteristic scintigraphic pattern and suggest the role of nuclear medicine scanning in establishing the diagnosis.

Adult↗
PubMed1985

Optimal technetium-99m RBC labeling for gastrointestinal hemorrhage study.

Four methods of Tc-99m red blood cell labeling were tested for labeling efficiency and kinetics in normal adults. From a perspective of the gastrointestinal hemorrhage study, the in vivo method was least appropriate because of extravascular loss of pertechnetate. The modified in vitro method was disadvantageous because of long labeling intervals in a syringe fixed to the patient's forearm (45 minutes). The pure in vitro methods produced the highest labeling efficiency (95% +) and are preferred by the authors.

Erythrocytes↗
PubMed1985

Dual isotope scanning with gallium-67 citrate and technetium-99m radiopharmaceuticals.

The interpretation of Ga-67 scans is limited by the complex anatomic and physiologic distribution of Ga-67 and by the low resolution possible with this isotope. The use of a second isotope Tc-99m, tagged to an appropriate pharmaceutical allows the identification of anatomic landmarks. Computer acquisition of both the Ga-67 and Tc-99m images allows for subtraction of the Tc-99m images from the Ga-67 images and leads to precise localization of abnormal Ga-67 accumulations. Only a small percentage of the counts in the Tc-99m window are due to Ga-67 scatter and do not degrade the Tc-99m images. Cases illustrating the value of the dual-isotope technique are presented.

Abscess↗
PubMed1985

Left ventricular volume determination from single-photon emission computed tomography.

To compare the accuracy of single-photon emission computed tomography (SPECT) with that of contrast cineangiography in measuring left ventricular end-diastolic volume, 25 consecutive patients undergoing catheterization for coronary artery or valvular heart disease were first evaluated scintigraphically. A simple, count-corrected voxel counting technique was used to derive left ventricular end-diastolic volume from transaxial SPECT slices. SPECT volume values showed a high degree of correlation with those determined by angiography (r = 0.969), with a standard error of the estimate of 23 ml. SPECT offers a highly accurate and essentially noninvasive method for measuring chamber volumes that is independent of geometric assumptions about ventricular configuration and chest wall attenuation and does not require blood sample counting.

Adult↗
PubMed1984

Patterns of intestinal activity with Meckel's scintigraphy.

Three patterns of intestinal activity were noted in a review of 64 patients studied with Tc-99m sodium pertechnetate for suspected Meckel's diverticulum: no bowel activity seen (37.5%), bowel activity visualized after stomach activity (39.1%), and diffuse bowel activity seen simultaneously with stomach activity (23.4%). The latter pattern, which is relatively common, could mask a true Meckel's diverticulum and lead to either a false-negative or indeterminate diagnosis. A series of 10 dogs was also studied to evaluate the effects of fasting and feeding on the intestinal pattern. No definite relationship was observed.

Adolescent↗
PubMed1984

Chest radionuclide angiography in the evaluation of pulmonary masses.

A retrospective analysis of 104 chest radionuclide angiography (CRNA) studies establishes the utility of this procedure in the evaluation of pulmonary malignancies and benign masses. Remarkable abnormalities in the perfusion of the lungs were identified in 36 (58%) of 62 cases that were not predictably normal or predictably abnormal form the clinical setting. While 60 of these 62 cases involved malignancy being evaluated for metastases, only 21 (34%) had metastases identified by radionuclide bone or liver-spleen scintigraphy. In addition to diagnosis of superior vena cava obstruction, the CRNA may have a more frequent application as an adjunct to routine scintigraphic studies directed to the identification of metastatic disease.

Adenocarcinoma↗
PubMed1984

SPECT hepatic scintigraphy "hot spot" localization.

The authors report a case of "hot spot" localization on SPECT hepatic scintigraphy secondary to IVC obstruction. The tomographic slices demonstrated the location of the focal increase in radiotracer activity as anterior, within the medial segment of the left lobe of the liver. Radionuclide angiography confirmed the extensive collateral vasculature of IVC obstruction.

Humans↗
PubMed1984

Scintigraphy of gastrointestinal hemorrhage: superiority of 99mTc red blood cells over 99mTc sulfur colloid.

The relative efficacy of 99mTc sulfur colloid and in vitro-labeled 99mTc red blood cells in detecting and localizing gastrointestinal hemorrhage was evaluated in a prospective tandem study of 100 patients referred for suspicion of gastrointestinal tract hemorrhage. Thirty-eight true-positive scintigrams were obtained with 99mTc red blood cells, whereas 99mTc sulfur colloid detected only five sites of hemorrhage. Scintigraphic findings were corroborated by clinical, endoscopic, arteriographic, and surgical findings. 99mTc red blood cells were clearly superior, with a sensitivity of 93%, specificity of 95%, and overall accuracy of 94% in detecting and localizing gastrointestinal hemorrhage.

Adolescent↗
PubMed1984

Biliary scintigraphy. The "hot rim" sign.

A new cholescintigraphic finding, the "hot rim" sign, is reported in a case of acute cholecystitis. Local inflammation in the gallbladder fossa may be the cause of this phenomenon.

Acute Disease↗