Biomedical subjects
Publications and source records attributed to J W Keyes.
Imaging of acute myocardial injury is possible with a large number of agents. All of these agents share similar patterns of uptake in acutely injured myocardial tissue. The technique appears to be a reliable way of ruling in or out the diagnosis of acute myocardial infarction.
The problem of nonuniform response, which is inherent in scintillationcamera emission computed tomography, can be minimized by proper collimator design. A specially fabricated collimator, optimized for emission computed tomography, was designed. This collimator has a calculated full width at half maximum of 1 cm at 15 cm in front of the collimator. When this collimator is used in conjunction with averaged opposed views, excellent uniformity across the reconstruction plane is achievable.
One hundred and seventy-four gallium scans of patients with biopsy-proved non-Hodgkin lymphoma were reviewed. When the lymphomas were subdivided into histologic groups, there was a significant difference in detection rates, with 62% of the histiocytic lymphomas being identified, while only 39% of the poorly differentiated lymphocytic lymphomas were detected. There was a high detection rate for lesions in the mediastinum and in extranodal locations. When analyzed with regard to therapy, the detection rate was higher in all histologic subgroups after therapy than before.
The accumulation of 99mtechnetium sulfur colloid (99mTcSC) was evaluated in 47 studies performed on 19 renal transplant patients by comparing its transplant activity to its bone marrow accumulation. There was a diagnosis of rejection of 21 of 22 studies (96.5%) in which marked transplant accumulation was noted. In 11 studies of patients with a clinical diagnosis of post-transplant acute tubular necrosis (ATN), the transplant activity varied from none to moderate. Rejection developed in 5 of 6 studies with minimal to moderate accumulation. Normally functioning renal transplant patients, or those with ATN and no superimposed rejection, do not show evidence of 99mTcSC accumulation.
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A single-photon emission tomographic system was used to study the normal anatomy of the facial bones and the usefulness of emission computed tomography in evaluating diseases of the bones of the face. The examination was performed following routine bone scintigraphy and took an additional 20-30 min. The anatomy of the facial bones was well defined, with clear separation of deep and superficial structures. Early experience with tumor, infection, bone grafts, and postirradiation osteonecrosis indicates that useful added diagnositc information can be obtained by this method.
An emission transaxial tomographic system using a scintillation camera as the detector is described. The unit allows accurate positioning of a scintillation camera's detector at any angle around a patient in order to obtain the multiple projection images needed for transaxial tomography, and it is capable of imaging any area of the body. The camera can also be used for all types of conventional imaging procedures. Image processing is performed by a small on-line computer. A convolution algorithm and a mathematical technique for approximate absorption correction are used to obtain high-resolution and high-contrast images with good quantitative accuracy. The operation of the system is described and representative phantom and patient studies are presented to illustrate the capabilities of the system.
Activity levels of 99TC-labeled compounds, 18F, and 85Sr were obtained at 1, 3, and 5 hr. postinjection in normal and healing fractured bone and in soft-tissue rat specimens. Serial diagnostic bone images and blood and urine kinetics were obtained in patients with each of the TC-labeled compounds. Computer-processed images were used to evaluate in vivo kinetics. 99mTC pyrophosphate provides the best overall characteristics for bone imaging. Improved quality and bioassay procedures are required, however, before any one agent can be designated the radiopharmaceutical of choice for diagnostic bone imaging.
Gallium citrate Ga 67 (67Ga) scans were performed in 50 consecutive lymphoma patients who underwent routine staging. The overall accuracy of 67Ga scans was greater than 80% for all nodal sites except the spleen (68%). Sensitivity was greater than 88% in the neck and mediastinum, 67% in the abdomen-pelvis, and 33% for the spleen. Specificity was greater than 85% for all nodal sites except for the mediastinum (67%). The accuracy of pedal lymphangiograms was 75%, sensitivity 87%, and specificity 68%. Gallium 67 scans complemented the lymphogram in the abdomen-pelvis but, due to limited sensitivity and high number of equivocal studies (16%), did not replace it. Infraclavicular, pectoral, and mediastinal lesions were detected by 67Ga scans when missed by other means. In 20% to 25% of patients, 67Ga scans provided information not afforded by other diagnostic studies and are therefore considered an important staging procedure for lymphoma patients.
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