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J Kegel

Publications and source records attributed to J Kegel.

6 recordsLinked to original sources
PubMed1994

Sequential dual-isotope SPECT imaging with thallium-201 and technetium-99m-sestamibi.

UNLABELLED: This study examined the results of sequential SPECT dual-isotope imaging with 201Tl and 99mTc-sestamibi in 148 patients, 114 of whom also had coronary angiography and 34 had < 5% pretest probability for coronary artery disease (CAD). METHODS: Stress thallium/rest sestamibi was used in 82 patients and rest thallium/stress sestamibi in 66 patients. Coronary angiography showed that 17 patients had no CAD, 27 patients had one-vessel CAD, 41 patients had two-vessel CAD and 29 patients had three-vessel CAD. The thallium study (3 mCi) was always done before the sestamibi study (20-25 mCi). The stress was either symptom-limited treadmill exercise testing or adenosine infusion at a rate of 140 micrograms/kg/min for 6 min. RESULTS: The study was completed within 2 hr. The stress and rest images were normal in 11 of 17 patients (65%) with no CAD by angiography and in 33 of 34 patients with a low pretest probability of CAD (normalcy rate = 97%). The images were abnormal in 75 patients with CAD (77%). The perfusion pattern was compared to wall motion in 485 segments (97 patients) assessed by contrast ventriculography. There were no or reversible perfusion defects in 357 of 386 segments (92%) with no wall motion abnormality. CONCLUSION: Sequential dual-isotope imaging is feasible and can be completed in a short period of time and may therefore enhance laboratory throughput and patient convenience.

Aged↗
PubMed1992

The perfusion pattern in coronary artery occlusion: comparison of exercise and adenosine.p6.

This study compared exercise to adenosine thallium-201 single photon emission computed tomography in detecting occlusion of left anterior descending or right coronary arteries in patients with no previous myocardial infarction. There were 41 patients who underwent adenosine thallium imaging (adenosine infusion at a rate of 140 micrograms/kg/min for 6 min), and 143 patients who underwent exercise thallium imaging. There were more patients with right coronary than left anterior descending coronary artery occlusion. Thus, in the adenosine group, there were 15 patients with left anterior descending artery occlusion, and 26 with right coronary artery occlusion, and in the exercise group, there were 46 patients with left anterior descending artery occlusion, and 97 patients with right coronary artery occlusion. In the adenosine group, the thallium images were abnormal in 41 patients (100%), while in the exercise group, the thallium images were abnormal in 125 patients (87%, P < 0.02) in the territories of the occluded arteries. ST segment depression was noted in 19 patients (46%) in the adenosine group, and 69 patients (48%) in the exercise group (P:NS). In patients with isolated single vessel occlusion, the size of the perfusion abnormality was 28 +/- 9% with adenosine, and 21 +/- 12% with exercise (P:NS). Thus, most patients with occlusion of the left anterior descending or right coronary artery have regional perfusion abnormality during stress; the different role of collaterals with each type of stress may explain the higher percentage of abnormal results with adenosine than exercise.

Adenosine↗
PubMed1992

Comparison of same-day protocols using technetium-99m-sestamibi myocardial imaging.

Two same-day protocols (rest/exercise [Protocol 1] and exercise/rest [Protocol 2]) with sestamibi (hexakis 2-methoxy-2-isobutyl-isonitrile) were performed within 2 to 14 days of each other after randomization. The initial study in each protocol was done using a dose of 185-296 MBq of 99mTc-sestamibi. The second study in each protocol used a dose of 555-925 MBq. SPECT imaging was started 30 to 60 min after injection using a 180 degrees anterior arc. Segmental analysis was interpreted as normal, scar or ischemia (20 segments/patient). Among the protocols, there was concordance in 93% of the segments (593/640 segments). In the 11 patients with coronary artery disease and no prior myocardial infarction who had ischemic abnormality, count densities from abnormal and normal zones were compared between the two protocols. Protocol 1 showed greater count differences between abnormal and normal zones on exercise images with better normalization of abnormality on rest images than Protocol 2 (p less than 0.05). Technetium-99m-sestamibi provides high quality images using either of the two same-day protocols. However, the rest/exercise protocol provides better image contrast and ability to detect reversibility of perfusion defects, and is the preferred same-day protocol.

Ambulatory Care↗
PubMed1989

[Computer-assisted determination of parameters of depth perception: studies with the 3-rod device].

Psychophysical determination of the thresholds of stereoscopic vision takes about 20 min. During this procedure, you may have the feeling that the thresholds are shifting. To verify this phenomenon, the thresholds must be determined in a period shorter than 20 min, e.g., 4-6 min. This is one of the reasons we constructed a computerized machine to detect the stereoscopic thresholds. The heart of this device is a micrometric screw driven by a stepping motor that moves the central rod of the three-rod apparatus. This motor is controlled by a microcomputer with a basic program. A special program has been designed that functions in a manner similar to that of the Octopus perimeter and detects the thresholds with in a few steps. It is thus possible to reduce the detection time for one threshold dramatically. The first results with this device are not only very precise, but also demonstrate the minute values between stereoscopic thresholds. For an observation distance of 380 mm, we were able to calculate the disparation angles down to 3 s of arc. If a number of measurements are taken, the threshold fluctuations and physiological zero position can be calculated.

Depth Perception↗