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Biomedical subjects

Z D Grossman

Publications and source records attributed to Z D Grossman.

18 recordsLinked to original sources
PubMed1992

Imaging of the human torso using cone-beam transmission CT implemented on a rotating gamma camera.

Radionuclide transmission CT generated on a rotating gamma camera can improve SPECT imaging by providing attenuation maps for attenuation compensation and for anatomical correlation. This paper demonstrates the feasibility and high quality of cone-beam transmission CT (CB-CT) of human subjects, in comparison to conventional parallel-ray CT, and evaluates some possible imaging protocols. Two CB-CT implementation modes, with a cone-beam collimator and without any collimator, were evaluated. Three human subjects of different dimensions were imaged. For the two smaller subjects, the CB-CT images were dramatically superior, in terms of noise and resolution, to those obtained with a parallel-ray geometry. The image noise was less by a factor of 6. CB-CT linear attenuation coefficients were found to be in close agreement with published values for various tissues. For the largest subject, image truncation produced a ring artifact at the edge, but inside the artifact, the image quality was still very good. Cone-beam images obtained without any collimator were acceptable, but photon scatter degraded the image contrast.

Body Height↗
PubMed1990

Thrombus imaging: a comparison of radiolabeled GC4 and T2G1s fibrin-specific monoclonal antibodies.

Radioimmunoimaging of experimentally-induced canine thrombi has previously been achieved with iodine-131- and indium-111-labeled (131I and 111In) anti-fibrin T2G1s monoclonal antibody (MAb). We now compare T2G1s to another anti-fibrin MAb, designated GC4, for imaging fresh and aged canine thrombi. GC4 is specific for a neoepitope exposed on fibrin later in the thrombolytic process after plasmin digestion. Femoral venous thrombi were induced in six groups of dogs, each containing three dogs. In two groups, the MAbs were compared when the thrombi were 3-hr or 3-days old at the time of injection, and the dogs were killed at 48 hr. In thrombi 3-hr-old, the GC4/T2G1s concentration ratio averaged 0.53 compared to 1.9 in 3-day-old thrombi. Two groups of dogs with thrombi 1- or 3-days-old were heparinized before MAb injection and were killed at 24 hr. The heparinized dogs with thrombi 1- or 3-days-old had GC4/T2G1s mean ratios of 2.3 and 2.9, respectively. In the unheparinized groups, the corresponding ratios were 1.1 and 1.9. GC4 may be more useful for clinical thrombus imaging than T2G1s because spontaneous venous thrombi are usually several days old at the time of presentation and patients are often heparinized immediately.

Angiography↗
PubMed1979

Radionuclide assessment of peritoneo-venous shunt patency.

LeVeen shunt patency can be easily assessed by sequential scintigraphy with a gamma camera after an intraperitoneal injection of Tc-99m-macroaggregated albumin (Tc-99m-MAA). If the shunt is patent, the particles of MAA reach the pulmonary capillary bed and the lungs are visualized. The activity in the lungs is easily discerned without any interference from radioactivity in the peritoneal cavity. The study is semiquantitative since the intensity of lung activity is directly proportional to the shunt patency and flow rate across shunt tubing.

Ascites↗
PubMed1979

Transmission computed tomographic diagnosis of experimentally produced acute pulmonary vascular occlusion in the dog.

Acute experimental pulmonary arterial occlusions were produced in 5 dogs. The chest was subsequently imaged with computed tomography (CT), 99mTc-MAA scintigraphy, and plain radiography. Gamma images revealed all 6 lesions, and plain radiographs were uniformly negative. Enhanced CT scans demonstrated 3 of 5 lesions, and unenhanced scans revealed 1 of 6. CT findings were variable.

Animals↗
PubMed1979

Transmission computed tomography, Tc-99m MAA scintigraphy, and plain chest radiography after experimentally produced acute pulmonary arterial occulusion in the dog.

We have occluded segmental and subsegmental pulmonary arteries in the dog with Swan-Ganz balloon catheters or i.v. injection of autologous clot, and have studied the chest with transmission computed tomography (TCT), Tc-99m-MAA gamma imaging, and plain radiographs. The arterial occlusions were between 1 and 5 hr old at the time of imaging. Radiographs revealed no lesions. Tc-99m MAA scanns revealed ten of 11 lesions. When a TCT image was made before i.v. injection of Renografin-60, two of 11 lesions were identified; after Renografin the score was four out of ten. The appearance of lesions on TCT was highly variable. Tc-99m-MAA gamma imaging, therefore, is far more accurate than TCT in the identification of small experimentally produced acute pulmonary arterial occlusions in the dog, and our study fails to suggest a secure place for TCT in the diagnosis of small, acute human pulmonary emboli. The commonly-held assumption that postembolic lung is oligemic is questioned.

Animals↗
PubMed1978

Effect of signaled versus unsignaled stress of rat myocardium.

Foot-shock stress resulted in a threefold increase in myocardial uptake of technetium-99m-methylene diphosphonate (Tc-99m-MDP) in rats compared to unstressed controls. The introduction of a 4-sec signal prior to each shock resulted in a two-thirds reduction in this stress-induced Tc-99m-MDP myocardial uptake, suggesting that most of the stress-induced myocardial damage was psychologically mediated.

Animals↗
PubMed1978

Experimental and clinical trials of new 99mTc-labeled hepatobiliary agents.

Several new derivatives of lidocaine were synthesized and used to examine the intra- and extrahepatic bile ducts and gallbladder. Diisopropyl-IDA exhibited approximately twice the bile concentration of 131I-rose bengal during the first hour after injection. P-butyl-IDA also concentrates moderately well in the bile and has the added advantage of very low excretion into the urine (2%). It seems more effective than the other IDA derivatives at high bilirubin levels.

Bile Ducts↗
PubMed1978

Labeling of platelets with oxine complexes of Tc-99m and In-111. Part 1. In vitro studies and survival in the rabbit.

We have used both Tc-99m oxine and In-111 oxine to study the effects in the rabbit of various parameters on platelet labeling and the in vivo survival of platelets harvested by four different methods. For In-111 oxine, platelet labeling in saline produces much higher efficiencies (90%) than labeling in the presence of plasma (20%), with no significant shortening of in vivo survival (1% survival at 5.9 days). For Tc-99m oxine, labeling efficiencies are considerably lower (30%) and survival is shorter (1% survival at 3.8 days). For both radioagents, a 30-min labeling incubation at room temperature is suggested.

Animals↗
PubMed1978

Platelets labeled with oxine complexes of Tc-99m and In-111. Part 2. Localization of experimentally induced vascular lesions.

Using rabbit platelets harvested and labeled with either Tc-99m or In-111 oxine as described in Part 1, we have successfully imaged experimentally induced fresh venous thrombi and newly injured arterial intima. Visualization of lesions up to 6 hr old is striking. Thrombi and arterial damage 24 hr old, however, were usually not imaged successfully; nor were preformed platelet-poor arterial emboli. The varying rates of platelet deposition in vascular lesions of different ages and types account for these observations. Should human cells prove as effective, widespread clinical application is anticipated.

Animals↗
PubMed1977

Correlation of computed tomography, gray scale ultrasonography, and radionuclide imaging of the liver in detecting space-occupying processes.

The abilities of computed tomography (CT; scanning time=2.7 min), gray scale ultrasonography, and radionuclide imaging to detect and characterize space-occupying processes in the liver were compared. A numerical rating scale which emphasized detection abilities resulted in ultrasonography scoring 3.5 CT 3.2, and radionuclide imaging 2.9. CT resulted in no false positives and 6 false negatives, caused mainly by motion artifacts. The simplest technique, radionuclide imaging, also had the smallest number (2) of false negatives; it is therefore recommended as the screening procedure of choice. Sonography or CT should be done for those patients with a prior suspicious finding.

Carcinoma, Hepatocellular↗
PubMed1977

Myocardial uptake (rabbit) of six 99mTc-tagged pharmaceuticals and 85Sr after vasopressin-induced necrosis.

A new rapid method for producing myocardial necrosis in rabbits was developed, using percutaneous intramyocardial injection of vasopressin in peanut oil. The 15-min procedure resulted in a mortality rate of 15% and a success rate among surviving animals of 50%. When the lesions were 24 hr old, strontium-85 and a technetium-99m-tagged agent were injected intravenously simultaneously, and the animals were killed 1,6, and 24 hr later for tissue radioassay. Strontium-85 failed to accumulate appreciably in the lesions. Three bone-seeking technetium complexes (pyrophosphate, methylene diphosphonate, and imidodiphosphonate) produced lesion-to-normal myocardial ratios of 6,5, and 14, respectively, at 1 hr, and 20,30, and 33 at 6 hr. The ratios for 99mTc-glucoheptonate were only 2 at 1 hr and 4 at 6 hr, while the ratios of 99mTc-acetylcysteine and 99mTc-citrate were even lower.

Animals↗
PubMed1977

Radionuclide imaging, computed tomography, and gray-scale ultrasonography of the liver: a comparative study.

Transmission computed tomography (CT), gray-scale ultrasonography, and scinitillation-camera imaging were compared for detection of intrahepatic space-occupying processes. Fifty patients with suspected liver disease were studied by the three modalities. In the 35 cases with confirmed abnormalities, the madalities were rated on a scale of 0 to 5 in terms of their detection value; Each modality was found to have definite advantages and disadvantages. The mean score of ultrasound was highest (3.61), followed by nuclear medicine (3.11) and then CT (2.77). The combination of ultrasound and nuclear medicine identified all lesions, whereas CT alone or in combination with another technique occasionally failed to detect abnormal foci. In the future, the relative efficacy of these procedures may change with improved imaging technology and increased interpreter experience.

Carcinoma, Hepatocellular↗
PubMed1977

Myocardial uptake of Tc-99m skeletal agents in the rat after experimental induction of microscopic foci of injury.

The cardiac uptake of Tc-99m tagged skeletal agents was studied after myocardial injury produced by subcutaneous catecholamine injection and random foot-shock stress. Rats stressed for 2 hr developed microfocal myocardial injury, without gross change, whereas those stressed for 12 hr sustained more confluent and sometimes grossly visible damage. Tc-99m MDP and Tc-99m PPi concentrations in these hearts were significantly above control (undamaged) heart levels, producing positive gamma-camera images. Subcutaneous epinephrine injections resulted in grossly visible lesions, with tracer concentrations higher than those previously reported in vasoocclusive infarcts. We postulate that the stress-induced scattered microfocal lesions may accumulate radiopharmaceutical on a per-gram basis in the same way as the larger catecholamine-induced lesions, since tracer delivery to the injured areas in each case is probably less impeded than in frankly vasoocclusive models. Such microfoci, then, could provide an explanation for some of the "false positive" myocardial scans observed clinically.

Animals↗
PubMed1976

Recognition of vertebral abnormalities in computed tomography of the chest and abdomen.

Computed tomography of the chest or abdomen may reveal vertebral abnormalities. Images in multiple projections of dry and fresh specimens of the spine demonstrate that osteophytes, end-plate irregularities, and marked obliquity fail to mimic true osteoblastic vertebral lesions. Disk calcification may simulate a metastatic deposit if the section includes both disk and vertebral body. Abdominal or chest "window" settings produce an apparent increase in bone density. Analysis of the bony spine from abdominal and chest images requires gray scale settings different from those used for the study of visceral organs.

Cervical Vertebrae↗