Transient ischemic dilation ratio in 82Rb PET myocardial perfusion imaging: Normal values and significance as a diagnostic and prognostic marker

Christoph Rischpler, Takahiro Higuchi, Kenji Fukushima, Mehrbod S. Javadi, Jennifer Merrill, Stephan G. Nekolla, Paco E. Bravo, Frank M. Bengel

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


In myocardial perfusion SPECT, transient ischemic dilation ratio (TID) is a well-established marker of severe ischemia and adverse outcome. However, its role in the setting of 82Rb PET is less well defined. Methods: We analyzed 265 subjects who underwent clinical rest-dipyridamole 82Rb PET/CT. Sixty-two subjects without a prior history of cardiac disease and with a normal myocardial perfusion study had either a low or a very low pretest likelihood of coronary artery disease or negative CT angiography. These subjects were used to establish a reference range of TID. In the remaining 203 patients with an intermediate or high pretest likelihood, subgroups with normal and abnormal TID were established and compared with respect to clinical variables, perfusion defect scores, left ventricular function, and absolute myocardial flow reserve. Follow-up was obtained for 969 6 328 d to determine mortality by review of the social security death index. Results: In the reference group, TID ratio was 0.98 ± 0.06. Accordingly, a threshold for abnormal TID was set at greater than 1.13 (0.98 + 2.5 SDs). In the study group, 19 of 203 patients (9%) had an elevated TID ratio. Significant differences between subgroups with normal and abnormal TID ratio were observed for ejection fraction reserve (5.0 ± 6.4 vs. 1.8 ± 7.9; P < 0.05), difference between end-systolic volume (ESV) at rest and stress (ΔESV[stress-rest]; 1.8 ± 7.4 vs. 12.3 ± 13.0 mL; P < 0.0001), difference between end-diastolic volume (EDV) at rest and stress (ΔEDV[stress-rest]; 10.8 ± 11.5 vs. 23.8 ± 14.6 mL; P < 0.0001), summed rest score (1.8 ± 3.8 vs. 3.8 ± 7.6; P < 0.05), summed stress score (3.0 ± 5.4 vs. 7.5 ± 9.8; P < 0.002), summed difference score (1.3 ± 2.6 vs. 3.7 ± 5.3; P < 0.02), and global myocardial flow reserve (2.1 ± 0.8 vs. 1.7 ± 0.6; P < 0.02). Additionally, TID-positive patients had a significantly lower overall survival probability (P < 0.05). In a subgroup analysis of patients without regional perfusion abnormalities, TID-positive patients' overall survival probability was significantly smaller (P < 0.03), and TID was an independent predictor (exponentiation of the B coefficients [Exp(b)] = 6.22; P < 0.009) together with an ejection fraction below 45% (Exp[b] = 6.16; P < 0.002). Conclusion: The present study suggests a reference range of TID for 82Rb PET myocardial perfusion imaging that is in the range of previously established values for SPECT. Abnormal TID in 82Rb PET is associated with more extensive left ventricular dysfunction, ischemic compromise, and reduced global flow reserve. Preliminary outcome analysis suggests that TID-positive subjects have a lower overall survival probability.

Original languageEnglish
Pages (from-to)723-730
Number of pages8
JournalJournal of Nuclear Medicine
Issue number5
Publication statusPublished - May 2012
Externally publishedYes


  • Myocardial perfusion imaging
  • Positron emission tomography
  • Rb
  • Transient ischemic dilation

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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