Normal values of myocardial blood flow measured with dynamic myocardial computed tomography perfusion.

AIMS: Dynamic myocardial computed tomography (CT) perfusion (DM-CTP) can, in combination with coronary CT angiography (CCTA), provide anatomical and functional evaluation of coronary artery disease (CAD). However, normal values of myocardial blood flow (MBF) are needed to identify impaired myocardial blood supply in patients with suspected CAD. We aimed to establish normal values for MBF measured using DM-CTP, to assess the effects of age and sex, and to assess regional distribution of MBF. METHODS AND RESULTS: A total of 82 healthy individuals (46 women) aged 45-78 years with normal coronary arteries by CCTA underwent either rest and adenosine stress DM-CTP (n = 30) or adenosine-induced stress DM-CTP only (n = 52). Global and segmental MBF were assessed. Global MBF at rest and during stress were 0.93 ± 0.42 and 3.58 ± 1.14 mL/min/g, respectively. MBF was not different between the sexes (P = 0.88 at rest and P = 0.61 during stress), and no correlation was observed between MBF and age (P = 0.08 at rest and P = 0.82 during stress). Among the 16 myocardial segments, significant intersegmental differences were found (P < 0.01), which was not related to age, sex, or coronary dominance. CONCLUSION: MBF assessed by DM-CTP in healthy individuals with normal coronary arteries displays significant intersegmental heterogeneity which does not seem to be affected by age, sex, or coronary dominance. Normal values of MBF may be helpful in the clinical evaluation of suspected myocardial ischaemia using DM-CTP.

Quantification of myocardial blood flow using dynamic myocardial CT perfusion compared with 82Rb PET.

PURPOSE: Absolute measures of myocardial blood flow (MBF) obtained with dynamic myocardial CT perfusion (DM-CTP) are underestimated when compared with reference standards. This is to some extent explained by incomplete extraction of iodinated contrast agent (iCA) to the myocardial tissue. We aimed to establish an extraction function for iCA, use the function to calculate MBFCT and to compare this with MBF measured with 82Rb positron emission tomography (PET). MATERIALS AND METHODS: Healthy individuals without coronary artery disease (CAD) were examined with 82Rb PET and DM-CTP. The factors a and ß of the generalized Renkin-Crone model were estimated using a non-linear least squares model. The factors providing the best fit for the data were subsequently used to calculate MBFCT. RESULTS: Of consecutive 91 individuals examined, 79 were eligible for analysis. The factors a and ß providing the best fit of the nonlinear least-squares model to the data were a â€‹= â€‹0.614 and ߠ​= â€‹0.218 (R-squared â€‹= â€‹0.81). Conversion of the CT inflow parameter (K1) values using the derived extraction function resulted in a significant correlation between MBF measured during stress using CT and PET (P â€‹= â€‹0.039). CONCLUSION: In healthy individuals, flow estimates obtained with dynamic myocardial CT perfusion during stress were, after conversion to MBF using the extraction of iodinated CT contrast agent, correlated with absolute MBF quantified with 82Rb PET.

Optimization of image sampling rate to lower the radiation dose of dynamic myocardial CT perfusion.

BACKGROUND: Dynamic myocardial CT perfusion (CTP) has emerged as a potential strategy to combine anatomical and functional evaluation in a single modality. However, this method results in a high radiation dose. METHODS: Dynamic CTP was performed in 56 patients with suspected or known ischemic heart disease of whom 48 had complete CT-data. Datasets with reduced sampling rate of 2- and 3 RR-intervals (2RR and 3RR) were constructed post hoc. Myocardial blood flow (MBF) estimates from the 2RR and 3RR datasets were compared with estimates based on the full dataset (1RR) using the two one-sided test of equivalence for paired samples. RESULTS: Significant equivalence was found for rest MBFLV (p â€‹< â€‹0.001), stress MBFLV (p â€‹< â€‹0.001) and for the CFRLV (p â€‹= â€‹0.005) when comparing 2RR blood flow estimates with the results based on the 1RR dataset. The 2RR reconstruction protocol led to an estimated reduction in radiation dose of 35.4 â€‹± â€‹3.8%. CONCLUSION: MBF can be quantitated with dynamic CTP using a sampling strategy of one volume for every second heartbeat. This strategy could lead to a significant reduction in radiation dose.

Single-phase coronary artery CT angiography extracted from stress dynamic myocardial CT perfusion on third-generation dual-source CT: Validation by coronary angiography.

BACKGROUND: CT advances allow coronary arterial tree to be entirely covered during one CTP scan. Our aim was to investigate the potential value of single-phase coronary CT angiography (SP-CCTA) extracted from stress dynamic myocardial CT perfusion (CTP) for coronary artery stenosis assessment. METHODS: Consecutive symptomatic patients were prospectively recruited and scanned with an ATP-stress dynamic myocardial CTP and routine CCTA protocol using third-generation DSCT. Noise reduction was applied to optimize image quality (IQ), the CTP phase with the best enhancement of the coronary arteries was selected as the SP-CCTA. IQ was assessed qualitatively. Using coronary angiography (CAG) as the reference standard, the diagnostic performance for stenosis detection was compared for SP-CCTA and routine CCTA. RESULTS: 56 patients underwent the CTP and CCTA examination, among which 39 patients underwent CAG. The qualitative IQ scores of SP-CCTA were similar to that of routine CCTA (p > 0.05). On a per-segment basis, the sensitivity, specificity, positive predictive value, negative predictive value, diagnostic accuracy and area under the receiver-operating-characteristic curve results of SP-CCTA and routine CCTA for diagnosis of stenosis ≥50% exhibited no significant difference (SP-CCTA: 78.1%, 94.9%, 77.4%, 95.1%, 91.6% and 0.935 vs. routine CCTA: 74.7%, 95.3%, 78.0%, 95.3%, 91.6% and 0.937; all p > 0.05). The mean effective radiation dose of CTP and routine CCTA plus CTP were 3.92 ±â€¯1.72 mSv and 5.98 ±â€¯2.01 mSv (p < 0.05), respectively. CONCLUSIONS: The IQ and diagnostic value of SP-CCTA was equivalent to routine CCTA on third-generation DSCT. SP-CCTA images from CTP may potentially replace a separate routine CCTA, allowing the possibility of "one-stop" cardiac examination for high-risk CAD patients who need myocardial ischemia assessment.