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Biomedical subjects

F D Rollo

Publications and source records attributed to F D Rollo.

At least 37 records · Page 2Linked to original sources
PubMed1981

Comparison of radionuclide and contrast ventriculography for detection and quantitation of regions of myocardial ischemia in dogs.

Radionuclide and contrast ventriculography were evaluated for their ability to estimate myocardial ischemia. In 14 closed-chest, sedated dogs, a small and larger region of ischemia were produced by inflating balloon occluders on the left anterior descending coronary artery. The systemic arterial pressure, atrial-paced heart rate, global ejection fraction by radionuclide and contrast ventriculography, regional wall-motion abnormalities (as the percentage of abnormally contracting segments), and regional myocardial blood flow (using the microsphere technique) were measured during an initial control period, two separate ischemic periods, and a final control period. The regional ischemic weights based on myocardial blood flow ranged from 0 to 38.5 g and were grouped as zero, small (range 0 to less than 10 g, mean 3.40 g), and large regions of ischemia (greater than 10 g, mean 24.8 g). Regional wall-motion abnormalities were sensitive qualitative indicators of ischemia. Receiver operating characteristic analysis showed that both ventriculographic methods were highly sensitive, specific, and accurate for detecting regional ischemia. Contrast ventriculography was slightly superior for detecting small regions less than 4 g, but the methods were equal for regions greater than 4 g. The arterial pressure and heart rate were unchanged during ischemia. For small regions of ischemia, the global ejection fraction did not fall using either the contrast or radionuclide technique, but it fell significantly when large regions were produced. There was a quantitative relationship between the percentage of abnormally contracting segments and the grams of myocardial ischemia (for radionuclide ventriculography, r = 0.65, P = 0.003, and for contrast ventriculography, r = 0.75, P less than 0.001), but for many small regions of ischemia, wall-motion changes were greater than anticipated, suggesting hypofunction of the continguous normal tissue. This study demonstrated that both radionuclide and contrast ventriculography were quite sensitive and specific for detecting measured amounts of regional ischemia. The functional changes resulting from ischemia are quantitatively related to the extent of regional ischemia, small areas resulting in regional wall motion abnormalities, and large areas producing both reduced global ejection fraction and wall motion changes.

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↗
PubMed1980

Correlation of 99mTc-pyrophosphate myocardial accumulation with left ventricular wall motion abnormalities.

Reports have indicated that myocardial accumulation of 99mTc-pyrophosphate occurs in the absence of a recent myocardial infarction. An attempt was made to determine if myocardial accumulation, in the absence of a recent infarction, may be associated with left ventricular wall motion abnormalities. 51 patients undergoing elective left ventriculography had 99mTc-pyrophosphate cardiac scans 24-28 h prior to the procedure. 33 (33/51) patients had myocardial accumulation; all 33 had left ventrcular wall motion abnormalities. Localized myocardial accumulation occurred in 21 (21/33) patients; 19 of the 21 had localized left ventricular wall motion abnormalities corresponding to the area of myocardial accumulation. 12 (12/33) patients had diffuse myocardial accumulation; 4 had diffuse left ventricular hypokinesis and 8 had localized myocardial dysfunction. 18 (18/51) patients had no myocardial accumulation of the radionuclide; 9 had normal wall motion in all areas and 9 had localized dysfunction. The data strongly suggest that myocardial accumulation of 99mTc-pyrophosphate in the absence of a recent myocardial infarction is associated with a left ventricular wall motion abnormality.

Adult↗
PubMed1980

Imaging techniques for the radioimmunodetection of cancer.

Problems in the radioimmunodetection of cancer typically involve small lesions having low object contrast. As such, the imaging device utilized must have a high spatial resolution as well as high detection efficiency. In addition, the imaging device must be interfaced to a computer system to allow data manipulation to include background substraction, contrast enhancement, and organ subtraction techniques to be used. While the conventional scintillation camera is the most widely used imaging device in conventional nuclear medicine imaging procedures, this system does not provide adequate imaging performance for radioimmunodetection of cancer. This is true since these devices typically do not provide adequate object contrast when detecting small lesions in the presence of moderately high background activity. The Pho/Con (Searle Radiographics) is a tomographic imaging device which, when interfaced to a computer system, is capable of providing adequate lesion detection for this specialized procedure. The newest version of this tomographic imaging system has a spatial resolution and a detector efficiency which are comparable to those of the conventional scintillation camera. The system has the added advantage of relatively constant high-spatial-resolution performance as well as high sensitivity over a wide range of depths. In addition, the imaging process involves a rectilinear scanning motion which results in inherently uniform response in each plane of interest. These combined properties result in high detection of small lesions in cases where the object contrast is extremely low. These inherent imaging properties when combined with the improved contrast provided with computer manipulation of data make this system ideal for radioimmunodetection problems. In this paper, the importance of spatial resolution, count density, lesion size, and object contrast are discussed in relation to the detectability of lesions in radioimmunodetection of cancer. In addition, the characteristics of the Pho/Con and its advantages in lesion detection are described.

Computers↗
PubMed1978

Performance evaluations of recent wide field scintillation gamma cameras.

Performance characteristics of four recent wide field scintillation gamma cameras were evaluated for 140-keV gamma imaging. Parameters measured included intrinsic spatial resolution, energy resolution, uniformity and linearity distortion, and count-rate capability and its influence on the spatial resolution. The system performance of the cameras was compared with representative parallel-channel collimators in terms of spatial resolution and relative sensitivity. Visual imaging comparisons of each camera system were performed by taking images of Rollo phantom containing four different lesion sizes, with four different contrast ratios, for equal imaging time.

Evaluation Studies as Topic↗
PubMed1978

Sequential myocardial scintigraphy with technetium-99m stannous pyrophosphate following myocardial infarction.

Studies have shown that technetium-99m stannous pyrophosphate (Tc-PPi) is effective for the detection and imaging of acute myocardial infarction. Positive Tc-PPi myocardial scintigrams, however, have been reported in patients with other forms of heart disease and no evidence of recent myocardial infarction. To help define the usefulness of this test, we undertook a prospective study to ascertain when Tc-PPi myocardial scintigrams return to normal after myocardial infarction. Twenty patients with acute myocardial infarction were followed with Tc-PPi scintigrams at 1 and 2 wk, and 1, after infarction. The serial scintigrams revealed that a) 15 of 18 scintigrams were positive within the first week after infarction, b) the number of markedly positive scintigrams decreased promptly after the first week, and c) some scintigrams (11 of 18 at 1 mo, and 3 of 18 at 9 mo) remained positive throughout the study. The possible explanations for persistently positive scintigrams are discussed. Persistently positive scintigrams may hinder the usefulness of Tc-PPi myocardial scintigraphy for the diagnosis of acute myocardial infarction in patients who have had a myocardial infarction within the previous 9 mo.

Acute Disease↗
PubMed1977

Persistently abnormal brain scintigraphy after cerebral infarction.

The current literature indicates nuclear brain images typically return to normal within two to three months following an episode of cerebral infarction. In this report, two patients are described who demonstrated no significant change in their brain scan abnormalities 11 and 17 months following their strokes. Computed tomography confirmed the clinical impression that the persistent brain scan abnormalities were due to cerebral infarction rather than to neoplastic process.

Aged↗
PubMed1977

Comparative evaluation of 99mTc GH, 99mTcO4, and 99mTc DTPA as brain imaging agents.

The brain imaging properties of 99mTc glucoheptonate, 99mTc pertechnetate, and 99mTc DPTA are compared. Results demonstrate that optimum images are obtained at 90, 180, and 180 min., for 99mTc GH, 99mTc DTPA, and 99mTc perterchnetate, respectively. The former two images are not affected by prior bone imaging with 99mTc pyrophosphate, while 99mTc pertechnetate images are adversely affected. 99mTc glucoheptonate appears to be the superior agent for brain imaging, followed by 99mTc DTPA and 99mTc pertechnetate.

Brain Diseases↗
PubMed1977

Gallium bone scan in myelofibrosis: case report.

When gallium is injected into a patient who has received many transfusions, the resultant scan appears similar to a bone scan with renal excretion. This case report presents a 51-year-old man with myelofibrosis and myeloid metaplasia. Gullium-67 and 52Fe scans with 99mTc-pyrophosphate bone scintigrams are included.

Bone Marrow↗
PubMed1977

Estimation of thyroid depth and correction for I-123 uptake measurements.

A new technique has been developed to correct I-123 uptake measurements for the effect of gland depth. The method uses the effect of differential tissue absorption and/or scatter of photons of different energies, and measures the ratio of counts of the primary I-123 emission to the counts of the tellurium K shell x-ray to determine a depth-correction factor. A comparison of this new method against three previously reported methods indicates that the present method provides the most sensitive index of gland depth. The method is sensitive to depth changes, is not significantly dependent on detector distance (p greater than 0.05) for distances greater than 18 cm, and is not dependent on gland size (p greater than 0.25), within the range 20-40 ml. In a group of 40 patients, the ORINS phantom method was found to underestimate the mean gland depth by about 1 cm, thereby causing an average uptake error of 23%. The application of the depth-correction factor was found to change the interpretation of uptake estimates in approximately 10% of the cases in this limited series.

Humans↗