Elsevier

Journal of Nuclear Cardiology

Volume 5, Issue 3, May–June 1998, Pages 304-312
Journal of Nuclear Cardiology

Original article
Influence of patient height and weight and type of stress on myocardial count density during SPECT imaging with thallium-201 and technetium 99msestamibi

https://doi.org/10.1016/S1071-3581(98)90132-5Get rights and content

Abstract

Background. The aim of this study was to determine the variability in myocardial activity with 99mTc-labeled sestamibi and 201T1 tomographic imaging, and to correlate this variability with patient anthropometric data and type of stress.

Methods and Results. Conventional tomographic acquisition (all-purpose collimator, 30 views, 40 sec/view) was performed in 249 patients (155 with 99mTc-sestamibi, 84 with 201T1). Normal myocardium was identified in three short-axis tomographic slices between the base and mid-ventricle. To exclude abnormal myocardium, all myocardial activity below an 85% threshold of peak counts was excluded. The average counts per pixel in the remaining myocardium was determined. All data were normalized to a collimator sensitivity of 8.1 counts/min/kBq and corrected for decay. Myocardial count densities in both 201T1 and 99mTc-sestamibi studies exhibited a high degree of variability and varied by factors of 3 to 4 and 2.5 to 3 respectively, between the 10th and 90th percentile of count densities. All 99mTc-sestamibi studies showed an inverse correlation (R ∼ 0.7) between myocardial count density and patient weight. For stress 201T1 studies in male patients, a similar inverse correlation (R = 0.63) was found between patient weight and myocardial count density. No correlation was found for female patients. For rest 99mTc-sestamibi studies, the average myocardial count density was 1245 ± 297 counts/pixel for a 1.11 GBq (30 mCi) injection. This was similar with pharmacologic stress (1224 ± 297 counts/pixel per 1.11 GBq (30 mCi), but significantly higher with exercise (1569 ± 363 counts/pixel per 1.11 GBq (30 mCi) (p < 0.005).201Tl studies averaged 327 ± 97 counts/pixel (111 MBq [3mci]injection) with exercise and 374 ± 145 counts/pixel/111 MBq (3 mCi) with pharmacologic stress (p = NS). Redistribution studies after exercise/pharmacologic stress (with a 37 MBq [1 mci]reinjection) averaged 267 ± 83 counts/pixel (148 MBq [3+1 mci]) .

Conclusions. Measured count densities in the myocardium demonstrate a high degree of variability that is only weakly correlated with patient anthropometric data. Nevertheless, knowledge of the mean values of myocardial activity as a function of administered dose may be useful in the optimization of rapid imaging procedures for 99mTc-based perfusion agents.

References (24)

  • National Electrical Manufacturers Association

    Performance measurements of scintillation cameras

  • RJ Gibbons et al.

    Feasibility of tomographic 99m-Tc-hexakis-2-methoxy-2-methylpropyl-isonitrile imaging for the assessment of myocardial area at risk and the effect of treatment in acute myocardial infarction

    Circulation

    (1989)
  • Cited by (14)

    • A study on the optimization of the administered activity in myocardial perfusion SPECT imaging with Tc-99m according to body measurements

      2019, Physica Medica
      Citation Excerpt :

      A second limitation is that rest acquisitions were not included in the study, because many patients had a normal stress scan and, therefore, did not continue with the resting phase. Nevertheless, according to previous publications [5,7] stress and rest studies are not expected to have statistically significant differences with respect to count rate correlations with body weight. A third limitation is that the chest circumference in all patients was not measured in the exact examination position (right arm at patient’s right side and left arm raised above patient’s head) and therefore there could be some systematic error in these measurements, especially for female patients.

    View all citing articles on Scopus
    View full text