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Biomedical subjects

I D Greenberg

Publications and source records attributed to I D Greenberg.

12 recordsLinked to original sources
PubMed1994

Diagnostic imaging management in Manitoba: 1995-2000.

As part of a 5-year imaging management plan being developed for the single insurance carrier in Manitoba, the radiologic utilization for the province was reviewed. For the fiscal year 1993 (April 1, 1992, through March 31, 1993), 1,056,694 imaging studies were performed in a total patient population of 1,133,117 in 81 hospitals and 39 offices in which 648 units of equipment were operated by 773.4 full-time personnel at a cost of $100,302,812 ($75,227,109 in U.S. dollars). The skin dose for the total population for the year was 40,112 Gy, compared with 35,513 Gy in 1979. Since 1979, there has been a 9% increase in the number of radiologic examinations (from 972,426 examinations), a greater need for more personnel to conduct ultrasound, mammography, computed tomography, and magnetic resonance imaging examinations, and striking costs escalation (from $25,082,500 to $100,302,812). Reduction of total funding for imaging services will be possible only if the medical service infrastructure and physician behavior are altered, since imaging is a support service. Hospital services must be integrated and the infrastructure reduced, and physicians must adhere to guidelines and practice protocols for requesting consultations.

Health Care Costs↗
PubMed1992

Quantification of walking exercise required for improvement of dipyridamole thallium-201 image quality.

Dipyridamole 201Tl imaging is an accepted diagnostic procedure for the evaluation of patients unable to perform adequate treadmill exercise, but is limited by high infradiaphragmatic activity. While recent studies have shown that the addition of exercise reduces this activity, the amount of exercise needed to effect such an improvement is uncertain. To prospectively evaluate the amount of walking exercise required to produce improvement in image quality, 120 patients were randomized to either a control group receiving dipyridamole alone, or to dipyridamole supplemented with one of four exercise protocols. Ratios of heart-to-liver and heart-to-adjacent infradiaphragmatic activity were generated from anterior images acquired immediately following the test. Heart-to-total infradiaphragmatic activity was also graded semiquantitatively. Results showed improved target-to-background ratios as well as semiquantitative assessment of image quality for dipyridamole supplemented with exercise as compared to dipyridamole alone. No difference was seen between walking in place and Bruce treadmill exercise at Stage 0 or 0.5. A trend towards higher values was seen with Bruce Stage 1 exercise supplementation, but this did not reach statistical significance. No significant complications occurred during the study. We conclude that 3 min of walking exercise is a safe and effective means of improving the quality of dipyridamole 201Tl images.

Adult↗
PubMed1991

Reference range determination: the problem of small sample sizes.

The process of developing and validating a quantitative test includes determination of a reference range. Traditionally this has been taken as the mean +/- 2 standard deviations for a random sampling from a reference population. However, this method fails to recognize the substantial variability in the sample mean and standard deviation for the small sample sizes frequently encountered in nuclear medicine. A new approach, which involves calculating confidence intervals for the upper and lower bounds of the traditionally defined range, recognizes three ranges of values: normal, indeterminate, and abnormal. The principles of this approach are illustrated using differential renal function in twelve renal transplant donors. The 99mTc-DTPA differential uptake between 1 and 2 min gave a traditionally-defined single-kidney range of 50% +/- 8%, whereas with our method the normal range would be 50% +/- 6% with indeterminate ranges of 37%-44% and 56%-63%. These values are consistent with the wide variation in reference ranges reported in the literature, and suggest that much of this variability may be a statistical artifact resulting from inadequate sample sizes. A nomogram has been derived that permits the power of the reference range determination to be easily calculated from the sample size. Analysis of the effect of sample size on the accuracy of the upper and lower bounds of the reference range is advocated whenever small reference populations are used.

Humans↗
PubMed1991

Effect of exercise supplementation on dipyridamole thallium-201 image quality.

To determine the effect of different types of exercise supplementation on dipyridamole thallium image quality, 78 patients were prospectively randomized to one of three protocols: dipyridamole infusion alone, dipyridamole supplemented with isometric handgrip, and dipyridamole with low-level treadmill exercise. Heart-to-lung, heart-to-liver, and heart-to-adjacent infradiaphragmatic activity ratios were generated from anterior images acquired immediately following the test. Additionally, heart-to-total infradiaphragmatic activity was graded semiquantitatively. Results showed a significantly higher ratio of heart to subdiaphragmatic activity in the treadmill group as compared with dipyridamole alone (p less than 0.001) and dipyridamole supplemented with isometric handgrip exercise (p less than 0.001). No significant difference was observed between patients receiving the dipyridamole infusion, and dipyridamole supplemented with isometric handgrip exercise. We conclude that low-level treadmill exercise supplementation of dipyridamole infusion is an effective means of improving image quality. Supplementation with isometric handgrip does not improve image quality over dipyridamole alone.

Adult↗
PubMed1990

Diagnostic thyroid procedures and corresponding radiation doses in Manitoba: 1981-1985.

Data on nuclear medicine thyroid examinations performed in Manitoba (population 1 million) from 1981-1985 were collected, with more detailed demographic data obtained on 1,100 consecutive patients between June 1987 and January 1988. An average of 2,081 patients were examined per year, 81% female and 19% male, representing 8.4% of all nuclear medicine procedures. Typical administered activity and associated HE per patient were 238.0 MBq and 1.5 mSv for 99mTc, 7.4 MBq and 1.2 mSv for 123I, and 0.33 MBq and 3.9 mSv for 131I. Based on NCRP risk estimates with explicit corrections for age, sex, and radionuclide used, it is estimated that the rate of thyroid cancer induction is unlikely to exceed 0.56 y-1, of which about 10% would be fatal. This estimate is about a factor of 4 less than that generated using more generally applicable radiation protection risk estimates averaged over both sexes and all ages in the general population. The replacement of 131I with the present mix of radiotracers used for thyroid evaluation has resulted in a reduction of the estimated population detriment by a factor of 3.6.

Adolescent↗
PubMed1984

Effects of dopamine on cardiopulmonary function and left ventricular volumes in patients with acute respiratory failure.

We investigated cardiopulmonary effects of dopamine in patients with acute respiratory failure. Specifically, we wished to test the hypothesis that left ventricular filling pressure (Pcwp) would increase when cardiac output (CO) increased with dopamine. Dopamine (range, 5.5 to 20 micrograms/kg/min) increased blood pressure (BP) (p less than 0.001) Pcwp, CO, and stroke volume (SV) (p less than 0.005). Mean Pcwp increased (p less than 0.005) 45% with dopamine, from 11 to 16 mmHg. Qs/Qt increased with dopamine in association with an increase in mixed venous O2 tension, and arterial O2 tension remained constant. In 8 of these patients, left ventricular end-diastolic volume (LVEDV) and end-systolic volume (ESV) were measured using scintigraphic techniques. The LVEDV increased (p less than 0.01) in each patient after the administration of dopamine, and the mean change was from 134 to 163 ml. Although BP and LV afterload increased in each patient, there was no consistent change in LVESV after dopamine administration, i.e., ESV decreased in 1 patient, remained constant in 3, and increased in 4. Accordingly, because afterload increased in all patients and ESV did not, dopamine probably increased contractility. Because EDV increased in all patients, we concluded that the increase in SV with dopamine is explained by a combination of inotropic and peripheral vascular effects.

Acute Disease↗
PubMed1982

The distal femoral defect: technetium-99m pyrophosphate bone scan results.

To determine the scintigraphic findings in children with distal femoral defects (or subperiosteal desmoids) the authors retrospectively examined 94 sets of radiographs and technetium-99m pyrophosphate bone scans of 54 children. Twenty-four examples of distal femoral defects were identified in 19 children. Only two children demonstrate focally increased uptake of radionuclide in the distal femur. The positive bone scan was caused by osteomyelitis in one of these patients and by metastatic lymphoma in the other. None of the 17 other children with distal femoral defects on radiography had a corresponding focal increase in uptake of radionuclide. The bone scan appears to be a useful method for confirming that a distal femoral defect is benign and, when positive, indicates the presence of other disease.

Adolescent↗
PubMed1981

Renal transplant uptake of technetium-99m sulfur colloid in various time periods after transplantation.

The uptake of technetium-99m sulfur colloid (TSC) by transplanted kidneys undergoing rejection has been described. In this retrospective study, the value of TSC uptake in diagnosing renal rejection was studied in different time intervals after renal transplantation. Within 14 days after transplantation, increasing uptake was seen in 88% of 26 rejection episodes. In patients with acute tubular necrosis, 42% of their studies showed TSC uptake. TSC did not predict rejection within the three days prior to rejection. Sensitivity, specificity and accuracy of 128 TSC studies were compared at different thresholds of TSC uptake; at best, accuracy was only 76%. In later time intervals, a much smaller percentage of patients had increasing uptake with rejection; this tendency was to remain unchanged. Many non-rejection studies showed some TSC uptake. In chronic rejection, persistently marked uptake dominated prior to one year after transplantation, but not beyond this. Thus, within 14 days after transplantation, TSC uptake may support the diagnosis of rejection. Thereafter its value becomes greatly limited.

Evaluation Studies as Topic↗