Assessment Of Myocardial Perfusion Research Articles

Invasive Assessment of the Myocardial Microcirculation during Beating Heart Coronary Artery Bypass Grafting.

Coronary artery bypass grafting may be associated with several cardiac complications, including ischemia, acute myocardial infarction, arrhythmias, or hemodynamic instability. Accumulating evidence suggests that well-developed coronary collateral circulation may protect against adverse effects, including myocardial ischemia. Assessment of myocardial microvascular perfusion is, therefore, of great clinical interest in beating heart surgery. In this paper, myocardial microvascular perfusion is continuously assessed on the beating heart using laser Doppler flowmetry in consecutive patients who underwent coronary artery bypass grafting procedures. No significant (p = 0.110) differences were found between the averaged perfusion signal (n = 42) at the baseline, during artery occlusion, or after reperfusion (732.4 ± 148.0 vs. 711.4 ± 144.1 vs. 737.0 ± 141.2, respectively). In contrast, significantly different (p < 0.001) mean perfusion signals (n = 12) were found (805.4 ± 200.1 vs. 577.2 ± 212.8 vs. 649.3 ± 220.8) in a subset of patients who presented with hemodynamic instability and myocardial ischemia. Additionally, a strong positive correlation between the plasma levels of high-sensitivity troponin I and perfusion decrease level after artery occlusion was found (r = 0.854, p < 0.001). This study argues that myocardial microvascular perfusion remains constant during coronary artery bypass grafting on the beating heart in advanced coronary artery disease. This phenomenon is most likely due to an extensive coronary collateral circulation.

Outcomes in Anomalous Aortic Origin of a Coronary Artery Following a Prospective Standardized Approach

Anomalous aortic origin of a coronary artery (CA) is the second leading cause of sudden cardiac death in young athletes. Management is controversial and longitudinal follow-up data are sparse. We aim to evaluate outcomes in a prospective study of anomalous aortic origin of CA patients following a standardized algorithm. Patients with anomalous aortic origin of a CA were followed prospectively from December 2012 to April 2017. All patients were evaluated following a standardized algorithm, and data were reviewed by a dedicated multidisciplinary team. Assessment of myocardial perfusion was performed using stress imaging. High-risk patients (high-risk anatomy-anomalous left CA from the opposite sinus, presence of intramurality, abnormal ostium-and symptoms or evidence of myocardial ischemia) were offered surgery or exercise restriction (if deemed high risk for surgical intervention). Univariate and multivariable analyses were used to determine predictors of high risk. Of 201 patients evaluated, 163 met inclusion criteria: 116 anomalous right CA (71%), 25 anomalous left CA (15%), 17 single CA (10%), and 5 anomalous circumflex CA (3%). Patients presented as an incidental finding (n=80, 49%), with exertional (n=31, 21%) and nonexertional (n=32, 20%) symptoms and following sudden cardiac arrest/shock (n=5, 3%). Eighty-two patients (50.3%) were considered high risk. Predictors of high risk were older age at diagnosis, black race, intramural course, and exertional syncope. Most patients (82%) are allowed unrestrictive sports activities. Forty-seven patients had surgery (11 anomalous left CA and 36 anomalous right CA), 3 (6.4%) remained restricted from sports activities. All patients are alive at a median follow-up of 1.6 (interquartile range, 0.7-2.8) years. In this prospective cohort of patients with anomalous aortic origin of a CA, most have remained free of exercise restrictions. Development of a multidisciplinary team has allowed a consistent approach and may have implications in risk stratification and long-term prognosis.

Stress dynamic myocardial CT perfusion for symptomatic patients with intermediate- or high-risk of coronary artery disease: Optimization and incremental improvement between the absolute and relative myocardial blood flow analysis

BackgroundThe optimization of myocardial CT perfusion (CTP) assessment remains inconsistent and uncertain. Our aim was to explore the superior analysis selection and incremental improvement of myocardial blood flow (MBF) assessment on CTP in diagnosing hemodynamically significant coronary artery disease (CAD). MethodsSixty patients (43 men and 17 women; 61.38 ± 8.01 years) were prospectively recruited and underwent stress dynamic myocardial CTP examinations. Absolute and relative MBF was used for ischemia evaluation with the invasive coronary angiography and fractional flow reserve were used as the reference standard. Areas under the receiver operating characteristic curves (AUCs) and cutoff values were calculated and compared. ResultsThere were 151 vessels in 60 patients finally enrolled for analysis. The sensitivity, specificity, PPV, NPV and diagnostic accuracy for the absolute MBF value and relative MBF ratio were 82.76%, 98.92%, 97.96%, 90.20%, and 92.72% and 74.14%, 93.56%, 87.76%, 85.29%, and 86.09%, respectively. The absolute MBF value was superior than the relative MBF ratio in detecting ischemia (AUC, 0.955 [95%CI: 0.919–0.990] vs.0.906 [95%CI:0.857–0.954])(P = 0.02). For territories with both sensitivity and specificity ≤90%, the diagnostic accuracy increased from 79.1% to 88.4% when the specific data were assessed using the absolute MBF value instead of the relative MBF ratio. ConclusionsThe absolute MBF value from the endocardial myocardium on stress dynamic myocardial CTP showed superior diagnostic performance compared to the relative MBF ratio for the detection of myocardial ischemia in intermediate-to-high risk patients. The absolute MBF value provides an incremental benefit toward diagnostic performance for the relative MBF ratio evaluation.

Anomalous coronary arteries: what is known and what still remains to be learned?

To report what is known and unknown regarding coronary anomalies in children, particularly anomalous aortic origin of a coronary artery, efforts undertaken to answer several questions regarding evaluation and management of this challenging young population, and where the future is heading. Patients with anomalous aortic origin of a coronary artery (AAOCA) present as an incidental finding at least half of the time, advanced imaging is essential to define anatomic characteristics of this lesion, assessment of myocardial perfusion with stress cardiac magnetic resonance imaging is feasible and contributes to risk stratification, certain patient populations require invasive assessment of coronary flow with measurement of fractional flow reserve, and surgical intervention can be safely performed through long-term data on impact to prevent sudden events is lacking. Optimal risk stratification in AAOCA is yet to be defined, though substantial strides are being made with a standardized approach to the evaluation and management of these patients. Continued collaboration among centers and the scientific community will positively impact patients and families living with AAOCA.

P361 Assessment of accuracy and reproducibility of coronary flow reserve measured by SPECT in patients with known or suspected coronary artery disease

Abstract Funding Acknowledgements Spectrum Dynamics Background Traditional relative assessment of regional myocardial perfusion by single photon emission computed tomography (SPECT) has limited ability to identify multivessel coronary artery disease, as well as diffuse atherosclerosis and coronary microvascular dysfunction. Current gamma cameras with cadmium-zinc-telluride (CZT) detectors have higher temporal resolution and sensitivity and allow the acquisition of multi-frame images and quantification of absolute myocardial blood flow (MBF) and coronary flow reserve (CFR Purpose The aim of this study was to assess the accuracy and reproducibility of quantitative measurements of MBF and CFR obtained with a CZT SPECT system compared to PET in a cohort of patients with known or suspected coronary artery disease. Methods Accuracy was assessed in 22 patients who underwent dynamic rest/stress 99mTc-sestamibi-SPECT and 13N-ammonia PET myocardial perfusion imaging within two weeks of each other. Fourteen patients comprised the reproducibility cohort and underwent two dynamic 99mTc-sestamibi SPECT scans within two weeks. A rest/pharmacological stress single-day SPECT protocol was performed, using a 1:3 dose ratio. SPECT image reconstruction was performed using a spline-fitting method and SPECT MBF was quantified using a net retention kinetic model in commercially available software. Rest MBF and CFR were adjusted for heart-rate pressure product. Results Global MBF at rest and stress showed a good correlation between SPECT and PET (r = 0.814, p &amp;lt; 0.001). For global rest MBF the mean difference between the two techniques was -0.25 ± 0.24 ml/min/g, while for stress MBF mean difference was -0.21 ± 0.40 ml/min/g. We also observed a significant correlation between global SPECT and PET CFR measurements (r = 0.745, p &amp;lt; 0.001), with no significant difference between the two (mean difference: 0.16 ± 0.50). Regarding the reproducibility cohort, the correlation between global CFR measured by two SPECT scans was also significant (r = 0.616, p = 0.019), with a mean difference of 0.14 ±0.51. The mean difference between scans for rest MBF (-0.05 ± 0.19) and stress MBF (0.01 ± 0.42) were also not significant. Conclusion MBF and CFR quantification is feasible using a CZT gamma camera and provides accurate and reproducible results that correlate with 13N-ammonia PET. This may be of special relevance in sites where PET is not available, enabling MBF and CFR quantification with CZT SPECT cameras. Abstract P361 Figure.

408 Stress Cardiac Magnetic Resonance With In-Line AI Quantitative Perfusion Mapping; Clinical Experience for Ischaemia and Microvascular Dyfunction

Adenosine Stress Perfusion Cardiac Magnetic Resonance (CMR) is a highly accurate technique for non-invasive assessment of myocardial perfusion, as shown in recent CEMARC, MR-INFORM, SPINS and GADACAD trials. Quantitative perfusion mapping using convoluted neural network artificial intelligence (AI) reconstruction has been proposed to improve accuracy and diagnostic performance. 33 consecutive stress scans CMR clinically referred for evaluation of angina pectoris, performed on a 1.5T Siemens Aera system. Standard sequence was a free-breathing motion corrected FLASH dynamic perfusion after 140mcg/kg adenosine, compared to an investigational work-in-progress myocardial blood flow (MBF) dual bolus technique with automatic arterial input function quantitated in ml/min/g using 16-segment AHA model. 22 scans referred for ischaemia, 11 for microvascular dysfunction. Level-3 expert reader blindly evaluated grey-scale dynamic perfusion imaging, and separately evaluated quantitative perfusion maps. Scans were categorised as ischaemia, microvascular, or normal coronary physiology. Diagnostic confidence was measured on a Likert rating scale from 1 (unconfident) to 3 (very confident). 31/33 scans (94%) had successful perfusion mapping, with 2 excluded due to artefact from arrythmia or failed motion correction. 20/22 scans referred for ischaemia (91%) mapping improved diagnostic confidence (score 2.03 vs 2.88, P<0.001). For all 11 (100%) microvascular dysfunction cases perfusion mapping was diagnostic over standard imaging. Quantitative perfusion mapping improves diagnostic confidence and allows accurate separation of ischaemic vs microvascular causes of angina.

Semi-quantitative myocardial perfusion MRI in heart transplant recipients at rest: repeatability in healthy controls and assessment of cardiac allograft vasculopathy

BackgroundCardiac Allograft Vasculopathy (CAV) is a major cause of chronic cardiac allograft failure. Invasive coronary angiography (ICA) and intravascular ultrasound (IVUS) are the current diagnostic methods. Myocardial perfusion MRI has become a promising non-invasive method to evaluate myocardial ischemia, but has not been thoroughly validated in CAV. Our objective was to assess the repeatability of myocardial rest-perfusion MRI in healthy volunteers and its feasibility in detecting CAV in transplant patients (Tx). MethodsTwelve healthy volunteers and twenty transplant patients beyond the first year post- transplant underwent cardiac MRI at 1.5 T at rest including first-pass perfusion imaging in short axis (base, mid, apex) after injection of gadolinium. Volunteers underwent repeated cardiac MRI on different days (interval = 15.6 ± 2.4 days) to assess repeatability. Data analysis included semi-automatic contouring of endocardial and epicardial borders of the left ventricle (LV) and quantification of peak perfusion, time-to-peak (TTP) perfusion, and upslope of the perfusion curve. ResultsBetween scans and re-scans in healthy volunteers, peak signal intensity, slope, and TTP demonstrated moderate agreement (ICC = 0.53, 0.48, and 0.59, respectively; all, p < .001). Peak signal intensity, slope, and TTP were moderately variable with COV values of 23%, 42%, and 35%, respectively. Peak perfusion was significantly reduced in CAV positive (n = 9 Tx patients) compared to CAV negative (n = 11 Tx patients) groups (90.7 ± 27.0 vs 139.5 ± 30.2, p < .001). ConclusionCardiac MRI is a moderately repeatable method for the semi-quantitative assessment of first-pass myocardial perfusion at rest. Semi-quantitative surrogate markers of LV perfusion could play a role in CAV detection.

Long-term prognostic value of quantitative myocardial perfusion in patients with chest pain and normal coronary arteries

BackgroundPatients with chest pain and no obstructive coronary artery disease have shown a high incidence of major adverse cardiovascular events (MACE). We evaluated the role of absolute myocardial perfusion quantification in predicting all-cause mortality and MACE during long-term follow-up in this group of patients. MethodsWe studied 79 patients who underwent Nitrogen-13 ammonia PET for quantification of global myocardial blood flow (MBF) and myocardial flow reserve (MFR) due to suspected impaired myocardial perfusion. Patients with coronary artery disease (i.e., > 30% stenosis in one or more coronary arteries) were excluded. We assessed all-cause mortality and MACE. MACE was defined as the composite incidence of death, myocardial infarction (MI), or hospitalization due to heart failure. ResultsMedian follow-up was 8 (IQR: 3-14) years. Univariate Cox regression showed that only MFR (P = 0.01) was a predictor of all-cause mortality. Univariate Cox regression analysis showed that both MFR and Stress MBF were predictors of the composite endpoint of MACE (P < 0.001 and P = 0.01, respectively). ConclusionQuantitative assessment of myocardial perfusion may predict all-cause mortality and MACE in patients with chest pain and normal coronary arteries in the long-term follow-up.

Evaluation of computed tomography myocardial perfusion in women with angina and no obstructive coronary artery disease.

Women with angina and no obstructive coronary artery disease (CAD) have worse cardiovascular prognosis than asymptomatic women. Limitation in myocardial perfusion caused by coronary microvascular dysfunction (CMD) is one of the proposed mechanisms contributing to the adverse prognosis. The aim of this study was to assess myocardial perfusion in symptomatic women with no obstructive CAD suspected for CMD compared with asymptomatic sex-matched controls using static CT perfusion (CTP). We performed a semi-quantitative assessment of the left ventricular myocardial perfusion and myocardial perfusion reserve (MPR), using static CTP with adenosine provocation, in 105 female patients with angina and no obstructive CAD (< 50% stenosis) and 33 sex-matched controls without a history of angina or ischemic heart disease. Patients were on average 4years older (p = 0.04) and had a higher burden of cardiovascular risk factors. While global perfusion during rest was comparable between the groups (age-adjusted p = 0.12), global perfusion during hyperemia was significantly reduced in patients compared with controls (163 ± 23 HU vs. 171 ± 25 HU; age-adjusted p = 0.023). The ability to increase myocardial perfusion during adenosine-induced vasodilation was significantly diminished in patients (MPR 148% vs. 158%; age-adjusted p < 0.001). This remained unchanged after adjustment for cardiovascular risk factors (p = 0.008). Women with angina and no obstructive CAD have reduced hyperemic myocardial perfusion and MPR compared with sex-matched controls. Impaired myocardial perfusion may be related to the presence of CMD in some of these women.

Quantitative myocardial blush score (QuBE) allows the prediction of heart failure development in long-term follow-up in patients with ST-segment elevation myocardial infarction: Proof of concept study.

Acute myocardial infarction (AMI) might lead to left ventricular remodeling. Adequate myocardial perfusion is critical to prevent this adverse remodeling. Quantitative myocardial blush evaluator (QuBE) software, available on-line, is a simple analysis tool which enables the precise quan-tification of myocardial perfusion in the infarct area immediately after interventional treatment. The aim of this study was to assess whether the results of QuBE analysis might predict the development of heart failure (HF) in AMI patients in 3 year-long follow-up. Ninety five patients with first AMI, single vessel coronary artery disease, Killip class I at presentation were enrolled in the study. Angiograms were reanalyzed using the on-line QuBE software. Data on heart failure development (ICD 10 codes I50) provided by the National Health Fund were considered as primary outcome. QuBE values ranged from 0.0 to 25.3 arbitrary units, mean value was 9.9 ± 5.2 arbitrary units. QuBE correlated positively with myocardial blush grade (MBG; Spearman R = 0.342 at p < 0.05). Multivariate Cox proportional hazard modeling, adjusted for initial Thrombolysis in Myocardial In-farction (TIMI flow, and TIMI thrombus grade indicated QuBE score (1 unit increase - HR 0.919, 95% CI 0.846-0.999, p = 0.049) and left ventricular ejection fraction at discharge (1% increase - HR 0.936, 95% CI 0.902-0.971, p = 0.000) as independent predictors of HF development. The QuBE assessment of myocardial perfusion allows the prediction of HF development in the post-infarction period in this highly selective group of patients.

Assessment of attenuation correction for myocardial PET imaging using combined PET/MRI

ObjectiveTo evaluate the frequency of artifacts in MR-based attenuation correction (AC) maps and their impact on the quantitative accuracy of PET-based flow and metabolism measurements in a cohort of consecutive heart failure patients undergoing combined PET/MR imaging. MethodsMyocardial viability studies were performed in 20 patients following a dual-tracer protocol involving the assessment of myocardial perfusion (13N-NH3: 813 ± 86 MBq) and metabolism (18F-FDG: 335 ± 38 MBq). All acquisitions were performed using a fully-integrated PET/MR system, with standard DIXON-attenuation correction (DIXON-AC) mapping for each PET scan. All AC maps were examined for spatial misalignment with the emission data, total lung volume, susceptibility artifacts, and tissue inversion (TI). Misalignment and susceptibility artifacts were corrected using rigid co-registration and retrospective filling of the susceptibility-induced gaps, respectively. The effects of the AC artifacts were evaluated by relative difference measures and perceived changes in clinical interpretations. ResultsAverage respiratory misalignment of (7 ± 4) mm of the PET-emission data and the AC maps was observed in 18 (90%) patients. Substantial changes in the lung volumes of the AC maps were observed in the test–retest analysis (ratio: 1.0 ± 0.2, range: 0.8-1.4). Susceptibility artifacts were observed in 10 (50%) patients, while six (30%) patients had TI artifacts. Average differences of 14 ± 10% were observed for PET images reconstructed with the artifactual AC maps. The combined artifact effects caused false-positive findings in three (15%) patients. ConclusionStandard DIXON-AC maps must be examined carefully for artifacts and misalignment effects prior to AC correction of cardiac PET/MRI studies in order to avoid misinterpretation of biased perfusion and metabolism readings from the PET data.

No differences in rest myocardial blood flow in stunned and hibernating myocardium: insights into the pathophysiology of ischemic cardiomyopathy.

The human pathophysiology of stunned, hibernating and scarred myocardium in ischemic cardiomyopathy is a subject of controversy. While the "smart heart" theory postulates that reduced myocardial blood flow (MBF) at rest is responsible for myocytes switching to a state of hibernation, other theories suggest that a reduced myocardial flow reserve (MFR) may be the cause. We included 110 patients with ischemic cardiomyopathy. Based on quantitative myocardial perfusion assessment and viability imaging with 13N-NH3 and 18F-FDG positron emission tomography, respectively, as well as wall motion assessment from echocardiography, myocardial tissue was characterized as remote (i.e., normal myocardium), stunned (i.e., dysfunctional but viable myocardium with normal rest perfusion), hibernating (i.e., dysfunctional but viable myocardium with impaired rest perfusion), or scarred myocardium (i.e., non-viable myocardium). Compared to remote myocardium, dysfunctional but viable myocardium (including stunned and hibernating) had reduced rest MBF (0.89mL/min/g vs. 0.79 and 0.76mL/min/g, respectively; p < 0.001) and MFR (1.53 vs. 1.27 and 1.17; p < 0.001). Between stunned and hibernating myocardium, however, rest MBF and MFR did not differ (p = 0.40). In scarred myocardium, rest MBF was lowest (0.66mL/min/g; p < 0.001) but, in contrast to the other myocardial states, k2 (i.e., tracer washout) was increased (0.199/min vs. 0.178/min to 0.181/min; all p < 0.05 in pairwise comparison). In patients with ischemic cardiomyopathy, impaired MFR is associated with stunning and hibernation. These states of dysfunctional but viable myocardium have lower rest MBF compared to remote myocardium. At the end of the continuum, rest MBF is lowest in scar tissue and linked to increased rate of tracer washout.

Feasibility of myocardial perfusion assessment with contrast echocardiography: can it improve recognition of significant coronary artery disease in the ICU?

BackgroundDiagnosis of significant coronary artery disease (CAD) and acute coronary artery occlusion in ICU can be difficult, and an inappropriate intervention is potentially harmful. Myocardial contrast perfusion echo (MCPE) examines ultrasound contrast intensity replenishment curves in individual myocardial segments measuring peak contrast intensity and slope of return as an index of myocardial blood flow (units = intensity of ultrasound per second [dB/s]). MCPE could possibly serve as a triage tool to invasive angiography by estimating blood flow in the myocardium. We sought to assess feasibility in the critically ill and if MCPE could add incremental value to the clinical acumen in predicting significant CAD.MethodsThis is a single-centre, prospective, observational study. Inclusion criteria were as follows: adult ICU patients with troponin I > 50 ng/L and cardiology referral being made for consideration of inpatient angiography. Exclusion criteria were as follows: poor echo windows (2 patients), known ischaemic heart disease, and contrast contraindications. Seven cardiologists and 6 intensivists blinded to outcome assessed medical history, ECG, troponin, and 2D echo images to estimate likelihood of significant CAD needing intervention (clinical acumen). Clinical acumen, quantitative MCPE, and subjective (visual) MCPE were assessed to predict significant CAD.ResultsForty patients underwent MCPE analysis, 6 (15%) had significant CAD, and median 11 of 16 segments (IQR 8–13) could be imaged (68.8% [IQR 50–81]). No adverse events occurred. A significant difference was found in overall MCPE blood flow estimation between those diagnosed with significant CAD and those without (3.3 vs 2.4 dB/s, p = 0.050). A MCPE value of 2.8 dB/s had 67% sensitivity and 88% specificity in detecting significant CAD. Clinical acumen showed no association in prediction of CAD (OR 0.6, p = 0.09); however, if quantitative or visual MCPE analysis was included, a significant association occurred (OR 17.1, p = 0.01; OR 23.0, p = 0.01 respectively).ConclusionsMCPE is feasible in the critically ill and shows better association with predicting significant CAD vs clinical acumen alone. MCPE adds incremental value to initial assessment of the presence of significant CAD which may help guide those who require urgent angiography.

Quantitative cardiac MRI.

Cardiac MRI has become an indispensable imaging modality in the investigation of patients with suspected heart disease. It has emerged as the gold standard test for cardiac function, volumes, and mass and allows noninvasive tissue characterization and the assessment of myocardial perfusion. Quantitative MRI already has a key role in the development and incorporation of machine learning in clinical imaging, potentially offering major improvements in both workflow efficiency and diagnostic accuracy. As the clinical applications of a wide range of quantitative cardiac MRI techniques are being explored and validated, we are expanding our capabilities for earlier detection, monitoring, and risk stratification of disease, potentially guiding personalized management decisions in various cardiac disease models. In this article we review established and emerging quantitative techniques, their clinical applications, highlight novel advances, and appraise their clinical diagnostic potential. Level of Evidence: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:693-711.

ULTRASOUND CONTRAST-ENHANCED STRESS ECHOCARDIOGRAPHY WITH MYOCARDIAL PERFUSION FOR FUNCTIONAL ASSESSMENT OF INTERMEDIATE STENOSIS IN THE LEFT ANTERIOR DESCENDING CORONARY ARTERY IN PATIENT WITH PREMATURE VENTRICULAR COMPLEXE

The presence of the intermediate stenosis (30 to 50% of arterial diameter) according to coronary angiography in patients with premature ventricular complexes often represents a complicated clinical task and requires additional confirmation of myocardial ischemia. The present clinical case demonstrates the opportunities and potential benefits of contrast-enhanced stress echocardiography with assessment of myocardial perfusion in diagnosing the hemodynamic significance of the intermediate lesion of the left anterior descending artery in patient with premature ventricular complexes.

ULTRASOUND CONTRAST-ENHANCED STRESS ECHOCARDIOGRAPHY WITH MYOCARDIAL PERFUSION FOR FUNCTIONAL ASSESSMENT OF INTERMEDIATE STENOSIS IN THE LEFT ANTERIOR DESCENDING CORONARY ARTERY IN PATIENT WITH PREMATURE VENTRICULAR COMPLEXE

The presence of the intermediate stenosis (30 to 50% of arterial diameter) according to coronary angiography in patients with premature ventricular complexes often represents a complicated clinical task and requires additional confirmation of myocardial ischemia. The present clinical case demonstrates the opportunities and potential benefits of contrast-enhanced stress echocardiography with assessment of myocardial perfusion in diagnosing the hemodynamic significance of the intermediate lesion of the left anterior descending artery in patient with premature ventricular complexes.

Improved visualization of the coronary arteries using motion correction during vasodilator stress CT myocardial perfusion imaging

BackgroundVasodilator stress computed tomography perfusion (sCTP) imaging is complementary to coronary CT angiography (CCTA), used to determine the hemodynamic significance of coronary artery disease. However, it requires a separate image acquisition due to motion artifacts caused by higher heart rates during stress, resulting in increased iodine contrast dose and radiation. We sought to determine whether a novel motion correction algorithm applied to stress images would improve the visualization of the coronary arteries to potentially allow CCTA + sCTP evaluation in a single scan. Methods28 patients referred for clinically indicated CCTA (iCT, Philips) underwent sCTP imaging (retrospective-gating with dose modulation; 100 kVp and 250 mA; 5.2 ± 4.3 mSv) after regadenoson (0.4 mg, Astellas). Stress images were reconstructed using standard filtered back-projection (FBP) and also processed to generate interaction-free coronary motion-compensated back-projection reconstructions (MCR). Each coronary artery from standard FBP and MCR images was viewed side-by-side by a reader blinded to the reconstruction technique, who graded severity of motion artifact by segment (scale 0–5, with 3 as the threshold for diagnostic quality) and to measure signal-to-noise and contrast-to-noise ratios (SNR, CNR). ResultsVisualization scores were higher with MCR for all coronary segments, including 14/86 (16%) segments deemed as non-diagnostic on FBP images. SNR (7 ± 2) and CNR (15 ± 8) were unchanged by motion-correction (7 ± 3, p = 0.88 and 15 ± 5, p = 0.94, respectively). ConclusionsMCR improves the visualization of coronary anatomy on sCTP images without degrading image characteristics. This algorithm is an important step towards the combined assessment of coronary anatomy and myocardial perfusion in a single scan, which will reduce study time, radiation exposure and contrast dose.

Microsurgical head and neck reconstruction in patients with coronary artery disease: A perioperative assessment algorithm.

With the rising number of patients in advanced age receiving microsurgical procedures, coronary artery disease (CAD) and its challenging management is of increasing importance. Evidence based data concerning morbidity and mortality are rare. We present our experiences with this highly selected patient population and propose a preoperative assessment algorithm. Between January 2006 and May 2016, a total of 57 patients with CAD received 58 free flaps. Median age of our patients was 64 years (interquartile range 57.5-70.0). Squamous cell carcinoma was the reason for reconstruction in all cases. Defect of the buccal, gum, tongue, lip, trigone, palatal, and hypopharyngeal regions were reconstructed. Patient characteristics and comorbidities were recorded. We especially focused on the preoperative cardiac assessment and treatment of patients who were scheduled for microsurgical free tissue transfer such as medical history, cardiac risk assessment, and further cardiac testing such as Doppler-echocardiography and myocardial perfusion assessment. Intraoperative course as well as postoperative morbidity and mortality was described. About 54.4% of the selected cohort received cardiac catheterization due to a clinical preoperative cardiac assessment performed individually by the cardiologist on duty. In total, 52 fasciocutaneous anterolateral thigh flaps, four osteocutaneous fibula flaps, and two radial forearm flaps were performed. The flap survival rate was 96.6%. The overall surgical complication rate was 28.1% (16 patients), mostly due to wound infections (seven cases) and partial flap necrosis (four cases). Three patients died, resulting in a mortality rate of 5.2%. CAD patients receiving head and neck microsurgical reconstructions are still at high risk for adverse consequences due to surgery. The microsurgical community is requested to share the experience of those cases in order to develop reliable and evidence based statements of the perioperative risks and prognosis for these patients. We additionally introduce a standardized perioperative cardiac assessment and treatment algorithm for head and neck surgery patients with CAD.

Evaluation of Myocardial Perfusion by Computed Tomography - Principles, Technical Background and Recommendations.

Coronary computed tomography angiography (CCTA) has gained a prominent role in the evaluation of coronary artery disease. However, its anatomical nature does not allow the evaluation of the functional repercussion of coronary obstructions. It has been made possible to evaluate Myocardial computed tomography perfusion (Myocardial CTP) recently, based on myocardial contrast changes related to coronary stenoses. Several studies have validated this technique against the anatomical reference method (cardiac catheterization) and other functional methods, including myocardial perfusion scintigraphy and fractional flow reserve. The Myocardial CTP is performed in conjunction with the CCTA, a combined analysis of anatomy and function. The stress phase (with assessment of myocardial perfusion) can be performed before or after the resting phase (assessment of resting perfusion and coronary arteries), and different acquisition parameters are proposed according to the protocol and type of equipment used. Stressors used are based on coronary vasodilation (e.g. dipyridamole, adenosine). Image interpretation, similar to other perfusion assessment methods, is based on the identification and quantification of myocardial perfusion defects. The integration of both perfusion and anatomical findings is fundamental for the examination interpretation algorithm, allowing to define if the stenoses identified are hemodynamically significant and may be related to myocardial ischemia.

Qualitative assessments of myocardial ischemia by cardiac MRI and coronary stenosis by invasive coronary angiography in relation to quantitative perfusion by positron emission tomography in patients with known or suspected stable coronary artery disease

BackgroundTo relate findings of qualitative evaluation of first-pass perfusion-CMR and anatomical evaluation on coronary angiography (CA) to the reference standard of quantitative perfusion, cardiac PET, in patients with suspected or known stable coronary artery disease (CAD). Methods and ResultsForty-one patients referred for CA due to suspected stable CAD, prospectively performed adenosine stress/rest first-pass perfusion-CMR as well as 13N-NH3 PET on the same day, 4 ± 3 weeks before CA. Angiographers were blinded to PET and CMR results. Regional myocardial flow reserve (MFR) < 2.0 on PET was considered pathological. Vessel territories with stress-induced ischemia by CMR or vessels with stenosis needing revascularization had a significantly lower MFR compared to those with no regional stress-induced ischemia or vessels not needing revascularization (P < 0.001). In 4 of 123 vessel territories with stress-induced ischemia by CMR, PET showed a normal MFR. In addition, 12 of 123 vessels that underwent intervention showed normal MFR assessed by PET. ConclusionThe limited performance of qualitative assessment of presence of stable CAD with CMR and CA, when related to quantitative 13N-NH3 cardiac PET, shows the need for fully quantitative assessment of myocardial perfusion and the use of invasive flow reserve measurements for CA, to confirm the need of elective revascularization.