Myocardial Upslope Research Articles

Peripheral microvascular function is linked to cardiac involvement on cardiovascular magnetic resonance in systemic sclerosis-related pulmonary arterial hypertension.

Systemic sclerosis (SSc) is characterized by vasculopathy, inflammation, and fibrosis, and carries one of the worst prognoses if patients also develop pulmonary arterial hypertension (PAH). Although PAH is a known prognosticator, patients with SSc-PAH demonstrate disproportionately high mortality, presumably due to cardiac involvement. In this cross-sectional study, the relationship between cardiac involvement revealed by cardiovascular magnetic resonance (CMR) and systemic microvascular disease severity measured with nailfold capillaromicroscopy (NCM) in patients with SSc-PAH is evaluated and compared with patients with idiopathic PAH (IPAH). Patients with SSc-PAH and IPAH underwent CMR, echocardiography, and NCM with post-occlusive reactivity hyperaemia (PORH) testing on the same day. CMR imaging included T2 (oedema), native, and post-contrast T1 mapping to measure the extracellular volume fraction (ECV, fibrosis) and adenosine-stress-perfusion imaging measuring the relative myocardial upslope (microvascular coronary perfusion). Measures of peripheral microvascular function were related to CMR indices of oedema, fibrosis, and myocardial perfusion. SSc-PAH patients (n = 20) had higher T2 values and a trend towards a higher ECV, compared with IPAH patients (n = 5), and a lower nailfold capillary density (NCD) and reduced capillary recruitment after PORH. NCD correlated with ECV and T2 (r = -0.443 and -0.464, respectively, P < 0.05 for both) and with markers of diastolic dysfunction on echocardiography. PORH testing, but not NCD, correlated with the relative myocardial upslope (r = 0.421, P < 0.05). SSc-PAH patients showed higher markers of cardiac fibrosis and inflammation, compared with IPAH patients. These markers correlated well with peripheral microvascular dysfunction, suggesting that SSc-driven inflammation and vasculopathy concurrently affect peripheral microcirculation and the heart. This may contribute to the disproportionate high mortality in SSc-PAH.

Peripheral microvascular function is linked to cardiac involvement on CMR in systemic sclerosis-related pulmonary arterial hypertension patients

Abstract Background Systemic sclerosis (SSc) is characterized by vasculopathy, inflammation and fibrosis, and carries one of the worst prognosis in patients who also develop pulmonary arterial hypertension (PAH). Although PAH is a known prognosticator, SSc-PAH patients demonstrate disproportionately high morbidity and mortality, presumably due to cardiac involvement. Purpose To determine the pathophysiology of cardiac involvement in SSc, cardiovascular magnetic resonance (CMR) measures of perfusion, inflammation and fibrosis were compared between SSc-PAH and idiopathic PAH (IPAH) patients. In addition, the correlation between myocardial involvement on CMR and known markers of peripheral microvascular function was assessed. Methods Consecutive patients with SSc-PAH and IPAH of similar age and gender, consecutively underwent CMR imaging, and nailfold capillaroscopy (NC) with post-occlusive reactivity hyperaemia-test (PORH-test). CMR imaging included T2 mapping (inflammation), pre- and postcontrast T1 mapping to calculate the extracellular volume fraction (ECV, fibrosis), and adenosine-stress perfusion imaging to measure the relative myocardial upslope (microvascular perfusion), all measurements were performed on the left ventricle. These CMR markers were related to peripheral microvascular function by NC and PORH-test. Results Twenty SSc-PAH patients (71 [62–77] years, 14% male) and 5 IPAH patients (69 [47–77] years, 20% male) were included. SSc-PAH patients had higher ECV and T2 values than IPAH patients. NC showed lower average capillary density and reduced recruitment of capillaries after PORH in SSc-PAH patients, corresponding to impaired microvascular structure and function. Both higher ECV and T2 values correlated with lower average capillary density (r=−0.454 and −0.583, respectively, p&amp;lt;0.05 for both). Additionally, higher T2 values and lower relative myocardial upslope correlated with worse peripheral microvascular function measured by PORH-test (r=−0.471 and r=0.421, respectively, p&amp;lt;0.05 for both). Conclusion SSc-PAH patients showed higher markers of cardiac fibrosis and inflammation, compared to IPAH patients. These markers correlated well with worse peripheral microvascular function, suggesting that SSc-driven inflammation and vasculopathy concurrently affect peripheral microcirculation and the heart. This may have important therapeutic implications, for which future studies are warranted evaluating the role of anti-inflammatory/anti-fibrotic therapy. Funding Acknowledgement Type of funding sources: None.

Myocardial Deformation in Cardiac Amyloid Light-chain Amyloidosis: Assessed with 3T Cardiovascular Magnetic Resonance Feature Tracking

Clinically, assessment of myocardial function is essential in patients with amyloid light-chain cardiac amyloidosis (AL-CA) to predict outcome and determine therapeutic approach. The aim of this study was to investigate the feasibility of cardiovascular magnetic resonance (CMR)-derived feature tracking algorithm for assessing left ventricular (LV) myocardial deformation in AL-CA, and to determine if these abnormal myocardial deformation parameters are correlated to impaired LV myocardial microvascular dysfunction. A total of 42 AL-CA patients, including 26 with preserved systolic function and 16 with impaired LVEF, and 35 healthy controls were enrolled and underwent CMR examination. Our result indicated that AL-CA patients had significantly reduced global peak strain (PS) (longitudinal, circumferential, and radial) (all P < 0.05). AL-CA patients with normal LVEF showed preserved longitudinal PS at apical and significantly reduced longitudinal PS at mid and basal segments. By Spearman’s rank correlation analysis, the LV regional radial, circumferential, and longitudinal myocardial deformation values were correlated to myocardial upslope and MaxSI in CA, regardless of LVEF. This study indicated that the abnormal LV myocardial deformation of AL-CA patients can be monitored using feature tracking CMR, even in those with preserved LVEF; and the myocardial deformation was associated with coronary microvascular dysfunction.

Robust semi-automated quantification of cardiac MR perfusion using level set: Application to hypertrophic cardiomyopathy patient data

BackgroundRecently there have been several clinical MR perfusion studies in patients with hypertrophic cardiomyopathy (HCM) who may suffer from myocardial ischemia due to coronary microvascular dysfunction. In these studies, data analysis relied on a manual procedure of tracing epicardial and endocardial borders. The goal of this work is to develop and validate a robust semi-automated analysis method for myocardial perfusion quantification in clinical HCM data. MethodDynamic multi-slice stress perfusion MRI data were acquired from 18 HCM patients. The proposed semi-automated method required user input of two landmark selections: LV center point and RV insertion point. Automated segmentations of the endocardial and epicardial borders were performed in three short-axis slices using distance regularized level set evolution on RV, LV, and myocardial enhancement frames. ResultsThe proposed automated epicardial border detection method resulted in average radial distance errors of 7.5%, 9.5%, and 11.6% in basal, mid, and apical slices, respectively, when compared to manual tracing of the borders as a reference. In linear regression analysis, the highest correlation of myocardial upslope measurements was observed between the manual method and the proposed method in the anterolateral section (r=0.964), and the lowest correlation was observed in the inferoseptal section (r=0.866). ConclusionThe proposed semi-automated method for myocardial MR perfusion quantification is feasible in HCM patients who typically show (1) irregular myocardial shape and (2) low image contrast between the myocardium and its surrounding regions due to coronary microvascular disease.

Regadenoson cardiovascular magnetic resonance myocardial perfusion imaging predicts need for future revascularization

Summary Regadenoson is a new vasodilator myocardial stress agent that is easier-to-use and more tolerable than adenosine. We demonstrate that, in patients undergoing cardiovascular magnetic resonance myocardial perfusion imaging, regadenoson is safe and effective in producing hyperemia and identifying the need for future revascularization. Background Regadenoson (Lexiscan; Astellas) is a new vasodilator myocardial stress agent that selectively activates the A2A receptor. Unlike adenosine, regadenoson is easier to administer and results in fewer side effects. Although extensively studied in patients undergoing nuclear myocardial perfusion imaging (MPI), its performance in cardiovascular magnetic resonance (CMR) MPI remains unknown. The aim of this study was to assess the safety and tolerability of regadenoson and determine its ability to produce hyperemia and predict subsequent coronary revascularization in patients undergoing CMR-MPI. Methods 120 patients were prospectively enrolled to receive CMR-MPI (Achieva, Philips 1.5T) with regadenoson. Patients with contraindications to CMR-MPI or regadenoson were excluded. Short-axis slices were obtained at three levels of the left ventricle (LV) during first pass of Gadolinium-DTPA(0.075 mmol/kg at 4 ml/sec) for 50 consecutive heart beats. Images were acquired using a hybrid gradient echo/echo planar imaging sequence. Imaging was performed 1 minute after injection of regadenoson (0.4mg) and then repeated 15 minutes after injection of aminophylline (125mg) under resting conditions. Perfusion defects were defined as subendocardial hypointensity in a coronary distribution at stress, involving ≥25% wall thickness, and persisting for ≥ 2h eart beats following peak enhancement of the LV cavity. In a subgroup of patients (n=99), custom software was used to generate time intensity curves and to compare the myocardial upslope of the midventricular slice during stress and rest. All subjects were followed for 3 months for the occurrence of coronary revascularization. Results Overall, 51/120 (43%) of patients were female with an average age of 55±15 years and body mass index of 29 ±6 kg/m2. Baseline patient characteristics include: coronary artery disease (33%), diabetes (38%), hypertension (56%), and hypercholesterolemia (95%). The average resting blood pressure and heart rate were 124/ 61mmHg and 70bpm, respectively. Peak heart rate after regadenoson administration was 98bpm (p<0.001). Most patients (87%) experienced side effects from regadenoson including shortness of breath (34%), flushing (23%), and chest discomfort (17%). No EKG changes or residual side effects persisted in any patient at completion of study. The average myocardial upslope increased significantly between rest and stress conditions (9.1±5.9 vs. 12.8±8.1, p<0.001), reflecting the expected hyperemic effect of regadenoson. Perfusion defects were visually apparent in 33/120 (28%) patients. Revascularization occurred in 8/120 (7%) patients (Figure 1). The presence

Characterization and Correction of Beam-hardening Artifacts during Dynamic Volume CT Assessment of Myocardial Perfusion

To fully characterize beam-hardening effects caused by iodinated contrast medium in the left ventricular (LV) cavity and aorta in the assessment of myocardial perfusion at computed tomography (CT) and to validate a beam-hardening artifact correction algorithm that considers fluid-filled vessels and chambers important sources of beam hardening. The Johns Hopkins University animal care and use committee approved all procedures. An anatomically correct LV and myocardial phantom to characterize beam-hardening artifacts was designed. Following validation in the phantom, the beam-hardening correction (BHC) algorithm was applied to 256-detector row dynamic volume CT images in a canine ischemia model (n = 5) during adenosine stress, and the effect of beam hardening was determined by comparing regional dynamic volume CT perfusion metrics (myocardial upslope normalized by maximum LV blood pool attenuation) with microsphere-derived myocardial blood flow (MBF). A paired Student t test was used to compare continuous variables from the same subject but under different conditions, while linear regression analysis was performed to estimate the slope and statistical significance of the relationship between CT-derived perfusion metrics and microsphere-derived MBF. Beam-hardening artifacts were successfully reproduced in phantom studies and were eliminated with the BHC algorithm. The correlation coefficient of CT-derived perfusion metrics and microsphere-derived MBF improved from 0.60 to 0.74 (P > .05) following correction in the animal model. Beam-hardening artifacts confound dynamic volume CT assessment of myocardial perfusion. Application of the BHC algorithm is helpful for improving accuracy of myocardial perfusion at dynamic volume CT.

MR Myocardial Perfusion Imaging with k-Space and Time Broad-Use Linear Acquisition Speed-up Technique: Feasibility Study

The purpose of this study was to prospectively evaluate the diagnostic accuracy of a cardiovascular magnetic resonance (MR) k-space and time (k-t) broad-use linear acquisition speed-up technique (BLAST) accelerated perfusion sequence for depicting clinically relevant coronary artery disease (CAD), with use of coronary angiography as the reference standard. The local ethics committee approved this study, and informed consent was obtained from 40 patients (28 men, 12 women; mean age, 61 years +/- 8 [standard deviation]) scheduled for coronary catheterization. A balanced steady-state free precession pulse sequence (2.6 x 2.6 x 10 mm) with a net k-t acceleration factor of 3.8 (repetition time msec/echo time msec, 3.2/1.6; flip angle, 50 degrees ) was applied. Visual analysis of perfusion images and quantitative analysis of signal-time curves obtained in the myocardium were performed by using segmental myocardial upslope, peak enhancement, and their respective ratios. Visual analysis revealed sensitivity, specificity, and diagnostic accuracy of 86%, 78%, and 83%, respectively, in the detection of coronary stenoses with at least 50% luminal narrowing. Significant (P < .05) changes between ischemic and remote segments could be shown for all perfusion indexes applied. Use of myocardial perfusion imaging with k-t BLAST for accelerated data acquisition is feasible in the identification of patients with substantial CAD (coronary stenosis >or= 50%). http://radiology.rsnajnls.org/cgi/content/full/245/3/863/DC1.

Determinants of Myocardial Response in CMR Perfusion Imaging Using Gd-BOPTA (Multihance®)

Different centers and vendors use different sequences and contrast agent application schemes for MR myocardial perfusion imaging. The purpose of this study was to evaluate the role of different sequences, dosages, and injection speeds of contrast media for semiquantitative MR-perfusion assessment. In a pilot study with 58 consecutive patients three of the most commonly used sequences for MR myocardial perfusion imaging (T1-GrE, GrE-EPI or SSFP) were compared to each other in terms of peak myocardial enhancement and image quality. For the main part of the study dynamic first pass MR perfusion imaging (Philips Intera CV, Best, Tthe Netherlands) was performed in 24 patients using the most favorable sequence from the pilot study (SSFP) after peripheral i.v. administration of Gd-BOPTA during adenosine stress. Two doses (0.05 mmol/kg bw and 0.025 mmol/kg bw) and four different injection speeds (8, 4, 3, 2 ml/s) were used. Signal intensity time curves were determined in the LV and myocardial segments supplied by normal coronary arteries and correlation between LV and myocardial upslope as well as peak enhancement were noted. The SSFP-sequence showed a higher peak enhancement when using 0.05 mmol/kg bw of Gd-BOPTA and a superior image quality for both dosage regimen compared with the other sequences and was consequently applied for the main study. A significant correlation was found between the upslopes in the LV and the myocardium (r square = 0.85, p < 0.001). However, LV and myocardial upslopes were largely independent of the dosage. Myocardial upslope was significantly slower at an injection rate of 2 ml/s compared to 3 and 4 ml/s. Higher Gd-doses led to significantly higher enhancement (p < 0.001). In healthy myocardial segments, the myocardial upslope is mainly determined from the LV upslope. Both myocardial enhancement and upslope are largely independent from the injection rate of a contrast agent bolus as long as the injection speed is not below 3 ml/s. Myocardial enhancement, however, is dose dependent. Thus, a simple correction for LV upslope allows to normalize a wide variety of input parameters. Differences of myocardial upslope or peak signal intensity after correction should be mainly dependent on blood flow.