Utility of single-shot compressed sensing cardiac magnetic resonance cine imaging for assessment of biventricular function in free-breathing and arrhythmic pediatric patients.

BACKGROUND: This study aimed to explore the feasibility and accuracy of single-shot compressed-sensing (CS) cardiac magnetic resonance cine technology for the assessment of biventricular function and morphology in free-breathing (FB) pediatrics, especially those with arrhythmia. METHODS: Seventy consecutive pediatric participants (6.27 ± 3.8 years, range:0.5-14 years) were enrolled between August 2019 and July 2020. Single-shot CS and conventional balanced steady-state free-precession (bSSFP) cine were obtained. The total scanning time, image quality and biventricular function parameters were compared for both sequences. RESULTS: Single-shot CS cine had shorter acquisition time compared with the conventional bSSFP cine (all P < 0.001). The single-shot CS cine also had fewer artifacts than conventional bSSFP cine (breath-hold (BH): 4.6 ± 0.6 vs. 4.3 ± 0.6; FB without ongoing arrhythmia: 4.5 ± 0.6 vs. 3.6 ± 0.9; FB with ongoing arrhythmia: 4.7 ± 0.5 vs. 2.6 ± 1.1; all P < 0.05). No statistical difference of left ventricular parameters and right ventricular end-systolic volume/ejection fraction were found between the single-shot CS and conventional bSSFP cine in both BH and FB without ongoing arrhythmia group. There was an excellent correlation (R2 = 0.60-0.98, all P < 0.001) and good intra-(range: R2 = 0.57-0.99, P < 0.001)/inter-observer agreements (range: R2 = 0.76-1, P < 0.001) for single-shot CS cine images in terms of biventricular function parameters. CONCLUSIONS: The single-shot CS cine can significantly reduce the image acquisition time, offering reliable quantification of biventricular function in free breathing condition for arrhythmic patients.

Noninvasive oxygenation assessment after acute myocardial infarction with breathing maneuvers-induced oxygenation-sensitive magnetic resonance imaging.

The safety profiles when performing stress oxygenation-sensitive magnetic resonance imaging (OS-MRI) have raised concerns in clinical practice. Adenosine infusion can cause side effects such as chest pain, dyspnea, arrhythmia, and even cardiac death. The aim of this study was to investigate the feasibility of breathing maneuvers-induced OS-MRI in acute myocardial infarction (MI). This was a prospective study, which included 14 healthy rabbits and nine MI rabbit models. This study used 3 T MRI/modified Look-Locker inversion recovery sequence for native T1 mapping, balanced steady-state free precession sequence for OS imaging, and phase-sensitive inversion recovery sequence for late gadolinium enhancement. The changes in myocardial oxygenation (ΔSI) were assessed under two breathing maneuvers protocols in healthy rabbits: a series of extended breath-holding (BH), and a combined maneuver of hyperventilation followed by the extended BH (HVBH). Subsequently, OS-MRI with HVBH in acute MI rabbits was performed, and the ΔSI was compared with that of adenosine stress protocol. Student's t-test, Wilcoxon rank test, and Friedman test were used to compare ΔSI in different subgroups. Pearson and Spearman correlation was used to obtain the association of ΔSI between breathing maneuvers and adenosine stress. Bland-Altman analysis was used to assess the bias of ΔSI between HVBH and adenosine stress. In healthy rabbits, BH maneuvers from 30 to 50 s induced significant increase in SI compared with the baseline (all p < 0.05). By contrast, hyperventilation for 60 s followed by 10 s-BH (HVBH 10 s) exhibited a comparable ΔSI to that of stress test (p = 0.07). In acute MI rabbits, HVBH 10 s-induced ΔSIs among infarcted, salvaged, and the remote myocardial area were no less effectiveness than adenosine stress when performing OS-MRI (r = 0.84; p < 0.05). Combined breathing maneuvers with OS-MRI have the potential to be used as a nonpharmacological alternative for assessing myocardial oxygenation in patients with acute MI. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.

Myocardial perfusion assessment in the infarct core and penumbra zones in an in-vivo porcine model of the acute, sub-acute, and chronic infarction.

OBJECTIVES: To assess the longitudinal changes of microvascular function in different myocardial regions after myocardial infarction (MI) using myocardial blood flow derived by dynamic CT perfusion (CTP-MBF), and compare CTP-MBF with the results of cardiac magnetic resonance (CMR) and histopathology. METHODS: The CTP scanning was performed in a MI porcine model 1 day (n = 15), 7 days (n = 10), and 3 months (n = 5) following induction surgery. CTP-MBF was measured in the infarcted myocardium, penumbra, and remote myocardium, respectively. CMR perfusion and histopathology were performed for validation. RESULTS: From baseline to follow-up scans, CTP-MBF presented a stepwise increase in the infarcted myocardium (68.51 ± 11.04 vs. 86.73 ± 13.32 vs. 109.53 ± 26.64 ml/100 ml/min, p = 0.001) and the penumbra (104.92 ± 29.29 vs. 120.32 ± 24.74 vs. 183.01 ± 57.98 ml/100 ml/min, p = 0.008), but not in the remote myocardium (150.05 ± 35.70 vs. 166.66 ± 38.17 vs. 195.36 ± 49.64 ml/100 ml/min, p = 0.120). The CTP-MBF correlated with max slope (r = 0.584, p < 0.001), max signal intensity (r = 0.357, p < 0.001), and time to max (r = - 0.378, p < 0.001) by CMR perfusion. Moreover, CTP-MBF defined the infarcted myocardium on triphenyl tetrazolium chloride staining (AUC: 0.810, p < 0.001) and correlated with microvascular density on CD31 staining (r = 0.561, p = 0.002). CONCLUSION: CTP-MBF could quantify the longitudinal changes of microvascular function in different regions of the post-MI myocardium, which demonstrates good agreement with contemporary CMR and histopathological findings. KEY POINTS: • The CT perfusion-based myocardial blood flow (CTP-MBF) could quantify the microvascular impairment in different myocardial regions after myocardial infarction (MI) and track its recovery over time. • The assessment of CTP-MBF is in good agreement with contemporary cardiac MRI and histopathological findings, which potentially facilitates a rapid approach for pathophysiological insights following MI.