Underestimation of myocardial blood flow by dynamic perfusion CT: Explanations by two-compartment model analysis and limited temporal sampling of dynamic CT

Masaki Ishida, Kakuya Kitagawa, Takashi Ichihara, Takahiro Natsume, Ryohei Nakayama, Naoki Nagasawa, Makiko Kubooka, Tatsuro Ito, Mio Uno, Yoshitaka Goto, Motonori Nagata, Hajime Sakuma

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

Purpose Previous studies using dynamic perfusion CT and volume perfusion CT (VPCT) software consistently underestimated the stress myocardial blood flow (MBF) in normal myocardium to be 1.1–1.4 ml/min/g, whilst the O 15-water PET studies demonstrated the normal stress MBF of 3–5 ml/min/g. We hypothesized that the MBF determined by VPCT (MBF-VPCT) is actually presenting the blood-to-myocardium transfer constant, K1. In this study, we determined K1 using Patlak plot (K1-Patlak) and compared the results with MBF-VPCT. Material and methods 17 patients (66 ± 9 years, 7 males) with suspected coronary artery disease (CAD) underwent stress dynamic perfusion CT, followed by rest coronary CT angiography (CTA). Arterial input and myocardial output curves were analyzed with Patlak plot to quantify myocardial K1. Significant CAD was defined as >50% stenosis on CTA. A simulation study was also performed to investigate the influence of limited temporal sampling in dynamic CT acquisition on K1 using the undersampling data generated from MRI. Results There were 3 patients with normal CTA, 7 patients with non-significant CAD, and 7 patients with significant CAD. K1-patlak was 0.98 ± 0.35 (range 0.22–1.67) ml/min/g, whereas MBF-VPCT was 0.83 ± 0.23 (range 0.34–1.40) ml/min/g. There was a linear relationship between them: (MBF-VPCT) = 0.58 x (K1-patlak) + 0.27 (r2 = 0.65, p < 0.001). The simulation study done on MRI data demonstrated that Patlak plot substantially underestimated true K1 by 41% when true K1 was 2.0 ml/min/g with the temporal sampling of 2RR for arterial input and 4RR for myocardial output functions. Conclusions The results of our study are generating hypothesis that MBF-VPCT is likely to be calculating K1-patlak equivalent, not MBF. In addition, these values may be substantially underestimated because of limited temporal sampling rate.

Original languageEnglish
Pages (from-to)207-214
Number of pages8
JournalJournal of Cardiovascular Computed Tomography
Volume10
Issue number3
DOIs
Publication statusPublished - 01-06-2016

All Science Journal Classification (ASJC) codes

  • Radiology Nuclear Medicine and imaging
  • Cardiology and Cardiovascular Medicine

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