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.

Normal values of aortic dimensions assessed by multidetector computed tomography in the Copenhagen General Population Study.

AIMS: Accurate assessment of aortic dimensions can be achieved using contrast-enhanced computed tomography. The aim of this study was to define normal values and determinants of aortic dimensions throughout multiple key anatomical landmarks of the aorta in healthy individuals from the Copenhagen General Population Study. METHODS AND RESULTS: The study group consisted of 902 healthy subjects selected from 3000 adults undergoing cardiovascular thoracic and abdominal computed tomography-angiography (CTA), where systematic measurements of aortic dimensions were performed retrospectively. Individuals included were without any of the following predefined cardiovascular risk factors: (i) self-reported angina pectoris; (ii) hypertension; (iii) hypercholesterolaemia; (iv) taking cardiovascular prescribed medication including diuretics, statins, or aspirin; (v) overweight (defined as body mass index ≥30 kg/m2); (vi) diabetes mellitus (self-reported or blood glucose >8 mmol/L); and (vii) chronic obstructive pulmonary disease. Maximal aortic diameters were measured at seven aortic regions: sinuses of Valsalva, sinotubular junction, ascending aorta, mid-descending aorta, abdominal aorta at the diaphragm, abdominal aorta at the coeliac trunk, and infrarenal abdominal aorta. Median age was 52 years, and 396 (40%) were men. Men had significantly larger aortic diameters at all levels compared with women (P < 0.001). Multivariable analysis revealed that sex, age, and body surface area were associated with increasing aortic dimensions. CONCLUSION: Normal values of maximal aortic dimensions at key aortic anatomical locations by contrast-enhanced CTA have been defined. Age, sex, and body surface area were significantly associated with these measures at all levels of aorta. Aortic dimensions follow an almost identical pattern throughout the vessel regardless of sex.

The relationship between volumetric thoracic bone mineral density and coronary calcification in men and women - results from the Copenhagen General Population Study.

BACKGROUND: The association between low bone mineral density (BMD) and the presence of coronary artery calcium (CAC) as a marker of atherosclerosis is unclear. The aim of this study was to assess the potential relationship between volumetric thoracic bone mineral density and coronary calcification in a large population of men and women. METHODS: Participants from the Copenhagen General Population Study underwent multidetector computed tomography. Volumetric thoracic BMD and CAC were assessed in the same scan. CAC was measured using calibrated mass score (cMS). cMS was dichotomized as cMS = 0 or cMS > 0. The association between BMD and cMS was analyzed using multiple logistic regression in men, premenopausal and postmenopausal women. The model was adjusted for age, BMI, hypertension, hypercholesterolemia, diabetes, known cardiovascular disease and smoking. RESULTS: Of 2548 eligible participants, 1163 men and 1385 women, mean age 61 ±â€¯10 were included in the study. Mean BMD was 138 ±â€¯46 mg/cm3 for men and 151 ±â€¯49 mg/cm3 women. In 696 men (67%) and 537 women (41%) cMS was found to be above zero. For men, a decrease in BMD of 100 mg/cm3 was associated to an odds ratio of 1.49 for cMS > 0 (95% confidence interval: 1.04-2.13, P = 0.03). In postmenopausal women, a decrease in BMD of 100 mg/cm3 was associated to an odds ratio of 1.47 for MS > 0 (95% confidence interval: 1.04-2.08, P = 0.03). For premenopausal women, no significant association was found between BMD and cMS (odds ratio = 0.74, 95% confidence interval: 0.36-1.52, P = 0.4). CONCLUSION: Bone mineral density and coronary calcification are inversely related in both men and postmenopausal women, supporting the hypothesis that a direct relation between bone loss and development of atherosclerosis exists irrespective of gender.

Performance of computed tomography-derived fractional flow reserve using reduced-order modelling and static computed tomography stress myocardial perfusion imaging for detection of haemodynamically significant coronary stenosis.

Aims: To compare the diagnostic performance of a reduced-order computed tomography-derived fractional flow reserve (CT-FFR) technique derived from luminal deformation and static CT stress myocardial perfusion (CTP). Methods and results: Forty-six patients (84 vessels) with suspected coronary artery disease from a single institution planned for elective coronary angiography prospectively underwent research indicated invasive fractional flow reserve (FFR) and 320-detector CT coronary angiography (CTA) and static CTP. Analyses were performed in separate blinded core laboratories for CT-FFR and CTP. CT-FFR was derived using a reduced-order model with dedicated software on a standard desktop computer. CTP was assessed visually and quantitatively by transmural perfusion ratio (TPR). Invasive FFR was significant in 33% (28/84) of vessels. Overall per-vessel sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy for CT-FFR were 81%, 84%, 71%, 90%, and 83%, respectively, those of visual CTP were 54%, 92%, 79%, 77%, and 78%, respectively, and TPR were 64%, 48%, 42%, 70%, and 54%, respectively. Per-vessel receiver operator curve analysis demonstrated a significantly larger area under the curve (AUC) for CT-FFR (0.89) with that for visual CTP (0.72; P = 0.016), TPR (0.55; P < 0.0001), and CTA (0.76; P = 0.04). The addition of CT-FFR to CTA provided superior improvement in performance (AUC 0.93; P < 0.0001) compared with CTA alone, a combination of CTA with visual CTP (AUC 0.82; P = 0.007) and CTA with TPR (AUC 0.78; P = 0.0006). Conclusion: Based on this selected cohort of patients, a reduced-order CT-FFR technique is superior to visual and quantitatively assessed static CTP in detecting haemodynamically significant coronary stenosis as assessed by invasive FFR.

Value of Myocardial Perfusion Assessment With Coronary Computed Tomography Angiography in Patients With Recent Acute-Onset Chest Pain.

OBJECTIVES: The authors sought to perform a randomized controlled trial to evaluate the clinical efficacy of combined examination with coronary computed tomography angiography (CTA) and computed tomography perfusion imaging (CTP) compared to coronary CTA alone. BACKGROUND: Stress myocardial CTP may increase diagnostic specificity when added to coronary CTA in patients suspected of having ischemic heart disease. METHODS: Patients recently hospitalized for acute-onset chest pain, who had acute coronary syndrome had been ruled out by normal electrocardiograms, normal troponin levels, and relief of symptoms, and who had a clinical indication for outpatient noninvasive testing, were screened for inclusion in the CATCH-2 (CArdiac cT in the treatment of acute CHest pain 2) trial (NCT02014311). Patients were randomized 1:1 to examination with coronary CTA or coronary CTA+CTP. The primary endpoint was the frequency of coronary revascularization among patients referred for invasive coronary angiography (ICA) based on index computed tomography evaluation. Secondary endpoints were invasive procedural complications at index-related ICA, post-index cardiac death, hospital admittance because of recurrence of chest pain, unstable angina pectoris, or acute myocardial infarction, ICA, and revascularization. RESULTS: Among 300 patients allocated to the coronary CTA+CTP group, 41 (14%) were referred for ICA compared with 89 (30%) allocated to coronary CTA (p < 0.0001). The primary endpoint occurred in 50% of coronary CTA+CTP patients versus 48% of invasively examined patients (p = 0.85). The total number of revascularizations was significantly lower in the coronary CTA+CTP group compared to the coronary CTA group (n = 20 [7%] vs. n = 42 [14%]; p = 0.0045). At median follow-up of 1.5 years, the occurrence of secondary endpoints was similar in the 2 groups. CONCLUSIONS: A post-discharge diagnostic strategy of coronary CTA+CTP safely reduces the need for invasive examination and treatment in patients suspected of having ischemic heart disease. (CArdiac cT in the treatment of acute CHest pain 2-Myocardial CT Perfusion [CATCH2]; NCT02014311).

Functional Information in Coronary Artery Disease: The Case of Computed Tomography Myocardial Perfusion.

PURPOSE OF REVIEW: To review methodological and logistical aspects of CT myocardial perfusion, current clinical evidence and possible future directions, with specific focus on use in patients with coronary artery disease (CAD). RECENT FINDINGS: CT myocardial perfusion imaging may be performed as an add-on to standard coronary CT angiography (CCTA), to identify regions of myocardial hypoperfusion, at rest and during adenosine stress. The principle of measurement is well-validated in animal experimental models, and CT myocardial perfusion imaging has a high degree of concordance with already clinically available perfusion imaging methods. Combining CCTA and CT myocardial perfusion imaging increases the diagnostic accuracy to identify patients with CAD associated with ischemia. In patients suspected of CAD, CCTA frequently detects coronary atherosclerotic lesions, in which revascularization could be clinically beneficial. CT myocardial perfusion imaging may be helpful to identify coronary lesions associated with myocardial ischemia, and thus potentially suitable for coronary intervention.