Multidetector CT coronary angiography: have we found the holy grail of non-invasive coronary imaging?

State-of-the-Art of Myocardial Perfusion by CMR: A Practical View

Ischemic heart disease (IHD) outstands among diseases threatening public health. Essential for its management are the continuous advances in medical and interventional therapies, although a prompt and accurate diagnosis and prognostic stratification are equally important. Besides information on the anatomy of coronary arteries, well covered nowadays by invasive and non-invasive angiographic techniques, there are also other components of the disease with clinical impact, as the presence of myocardial necrosis, the extent of pump function impairment, and the presence and extent of inducible myocardial ischemia, that must be considered in every patient. Cardiovascular Magnetic Resonance (CMR) is a multiparametric diagnostic imaging technique that provides reliable information on these issues. Regarding the detection and grading of inducible ischemia in particular, the technique has been widely adopted in the form of myocardial perfusion sequences under vasodilator stress, which is the subject of this review. While the analysis of images is conventionally performed by visual inspection of dynamic first-pass studies, with the inherent dependency on the operator capability, the recent introduction of a reliable application of quantitative perfusion (QP) represents a significant advance in the field. QP is based on a dual-sequence strategy for conversion of signal intensities into contrast agent concentration units and includes a full automatization of processes such as myocardial blood flow (MBF) calculation (in mL/min/g), generation of a pixel-wise flow mapping, myocardial segmentation, based on machine learning, and allocation of MBF values to myocardial segments. The acquisition of this protocol during induced vasodilation and at rest gives values of stress/rest MBF (in mL/min/g) and myocardial perfusion reserve (MPR), both global and per segment. Dual-sequence QP has been successfully validated against different reference methods, and its prognostic value has been shown in large longitudinal studies. The fact of the whole process being automated, without operator interaction, permits to conceive new interesting scenarios of integration of CMR into systems of entirely automated diagnostic workflow in patients with IHD.

Associations between coronary artery stenosis detected by coronary computed tomography angiography and the characteristics of health checkup examinees in the Republic of Korea

INTRODUCTION

This study was conducted on healthy adults without a diagnosis related to cardiovascular disease to investigate the associations between asymptomatic coronary artery stenosis and the characteristics of health checkup examinees.

METHODS

This study was performed on 601 people (320 males and 281 females), who underwent coronary computed tomography angiography (CCTA), among health checkup examinees from January 2, 2015 to December 31, 2016. Those with any prior history of cardiovascular diseases, underwent coronary artery bypass grafting or coronary artery stenting in the past, those with atrial fibrillation, those suspected of contrast agent side effects, and those whose creatinine levels deviated from the normal range were excluded.

RESULTS

The mean age was 58.7 ± 8.0 years. Coronary artery stenosis was detected in 173 people (28.8%), and the mean coronary artery stenosis rate was 25.8 ± 12.8%. Regression analysis showed that coronary artery stenosis was influenced significantly by age, gender, glycated hemoglobin (HbA1c), past smoking duration, current smoking duration, and number of glasses of alcohol consumed (p < 0.05). In terms of the relationship between the presence of coronary artery stenosis and lifestyle habits, amount of alcohol consumed per day (p = 0.03), and patients with a longer period of past (p < 0.001) and current smoking duration (p = 0.01) had a significant effect on coronary artery stenosis.

CONCLUSION

These results suggest that men aged 60 years or older, who have consumed large amounts of alcohol and cigarettes for a long time, require continuous management through tests such as a health checkup, because of the high probability of coronary artery stenosis, even in those without specific symptoms.

SYNTAX Score in Patients with High Computed Tomography Coronary Calcium Score

Objectives:

To study the conventional coronary angiogram ( CA) findings in patients with high coronary calcium on multidetector computed tomogram.

Materials and Methods:

Fifty patients with coronary calcium high enough in its extent and location to interfere with the interpretation of a contrast-filled coronary artery for a significant lesion were studied with conventional CA. Framingham risk score (FRS), computed tomography (CT) coronary calcium score (CCS), and SYNTAX score (SS) from the CA were calculated by separate investigators who were blinded to other scores. Effectively, 250 coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery and posterior descending artery in each subject) with calcium scores were studied for lesions on CA.

Results:

Thirty-five subjects had high FRS, 10 had intermediate FRS, and 5 had low FRS. Eight subjects of 25 (32%) with CCS between 350 and 1000 had no significant coronary artery disease (CAD). Overall, the CCS and the SS had a strong agreement with each other (r = 0.68, P < 0.01) that persisted in those with very high scores >1000 (r = 0.55, P < 0.01, n = 30), but only a nonsignificant weak correlation with scores between 350 and 1000 (r = 0.1, P = 0.62, n = 20). Individual vessel calcium scores correlated strongly for the presence of any lesion (r = 0.52, P < 0.01) in the same artery but only weakly for a significant lesion (r = 0.29, P = 0.05).

Conclusion:

High CT CCS in this cohort of intermediate to high (Framingham score) risk patients correlated strongly with the subject's global burden of the CAD as derived by the SS, more so for subjects with very high scores. Similarly, CCS correlated strongly with the presence of any lesion but only weakly for a significant stenosis; also, about one-third of patients with CCS between 350 and 1000 may not have significant disease on conventional CA.

Magnetic resonance myocardial perfusion imaging: a new era in the detection of reversible myocardial ischaemia

In due course, magnetic resonance myocardial perfusion imaging will probably replace SPECT as the most widely used non-invasive method for detecting reversible myocardial ischaemia.