Increased [18F]FDG uptake in the infarcted myocardial area displayed by combined PET/CMR correlates with snRNA-seq-detected inflammatory cell invasion.

Combined [18F]FDG PET-cardiac MRI imaging (PET/CMR) is a useful tool to assess myocardial viability and cardiac function in patients with acute myocardial infarction (AMI). Here, we evaluated the prognostic value of PET/CMR in a porcine closed-chest reperfused AMI (rAMI) model. Late gadolinium enhancement by PET/CMR imaging displayed tracer uptake defect at the infarction site by 3 days after the rAMI in the majority of the animals (group Match, n = 28). Increased [18F]FDG uptake at the infarcted area (metabolism/contractility mismatch) with reduced tracer uptake in the remote viable myocardium (group Mismatch, n = 12) 3 days after rAMI was observed in the animals with larger infarct size and worse left ventricular ejection fraction (LVEF) (34 ± 8.7 vs 42.0 ± 5.2%), with lower LVEF also at the 1-month follow-up (35.8 ± 9.5 vs 43.0 ± 6.3%). Transcriptome analyses by bulk and single-nuclei RNA sequencing of the infarcted myocardium and border zones (n = 3 of each group, and 3 sham-operated controls) revealed a strong inflammatory response with infiltration of monocytes and macrophages in the infarcted and border areas in Mismatch animals. Our data indicate a high prognostic relevance of combined PET/MRI in the subacute phase of rAMI for subsequent impairment of heart function and underline the adverse effects of an excessive activation of the innate immune system in the initial phase after rAMI.

Multicenter Standardization of Phase-Resolved Functional Lung MRI in Patients With Suspected Chronic Thromboembolic Pulmonary Hypertension.

BACKGROUND: Detection of pulmonary perfusion defects is the recommended approach for diagnosing chronic thromboembolic pulmonary hypertension (CTEPH). This is currently achieved in a clinical setting using scintigraphy. Phase-resolved functional lung (PREFUL) magnetic resonance imaging (MRI) is an alternative technique for evaluating regional ventilation and perfusion without the use of ionizing radiation or contrast media. PURPOSE: To assess the feasibility and image quality of PREFUL-MRI in a multicenter setting in suspected CTEPH. STUDY TYPE: This is a prospective cohort sub-study. POPULATION: Forty-five patients (64 ± 16 years old) with suspected CTEPH from nine study centers. FIELD STRENGTH/SEQUENCE: 1.5 T and 3 T/2D spoiled gradient echo/bSSFP/T2 HASTE/3D MR angiography (TWIST). ASSESSMENT: Lung signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared between study centers with different MRI machines. The contrast between normally and poorly perfused lung areas was examined on PREFUL images. The perfusion defect percentage calculated using PREFUL-MRI (QDPPREFUL ) was compared to QDP from the established dynamic contrast-enhanced MRI technique (QDPDCE ). Furthermore, QDPPREFUL was compared between a patient subgroup with confirmed CTEPH or chronic thromboembolic disease (CTED) to other clinical subgroups. STATISTICAL TESTS: t-Test, one-way analysis of variance (ANOVA), Pearson's correlation. Significance level was 5%. RESULTS: Significant differences in lung SNR and CNR were present between study centers. However, PREFUL perfusion images showed a significant contrast between normally and poorly perfused lung areas (mean delta of normalized perfusion -4.2% SD 3.3) with no differences between study sites (ANOVA: P = 0.065). QDPPREFUL was significantly correlated with QDPDCE (r = 0.66), and was significantly higher in 18 patients with confirmed CTEPH or CTED (57.9 ± 12.2%) compared to subgroups with other causes of PH or with excluded PH (in total 27 patients with mean ± SD QDPPREFUL = 33.9 ± 17.2%). DATA CONCLUSION: PREFUL-MRI could be considered as a non-invasive method for imaging regional lung perfusion in multicenter studies. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 1.

Randomized Trial of Etelcalcetide for Cardiac Hypertrophy in Hemodialysis.

[Figure: see text].

Evaluation of perivascular fat attenuation with coronary CT angiography in cardiac transplantation patients: an imaging biomarker candidate for prediction of cardiac mortality and re-transplantation.

OBJECTIVES: In cardiac transplant recipients, non-invasive allograft surveillance for identifying patients at risk for graft failure remains challenging. The fat attenuation index (FAI) of the perivascular adipose tissue in coronary computed tomography angiography (CCTA) predicts outcomes in coronary artery disease in non-transplanted hearts; however, it has not been evaluated in cardiac transplant patients. METHODS: We followed 39 cardiac transplant patients with two or more CCTAs obtained between 2010 and 2021. We performed FAI measurements around the proximal 4 cm segments of the left anterior descending (LAD), right coronary artery (RCA), and left circumflex artery (LCx) using a previously validated methodology. The FAI was analyzed at a threshold of - 30 to - 190 Hounsfield units. RESULTS: FAI measurements were completed in 113 CCTAs, obtained on two same-vendor CT models. Within each CCTA, the FAI values between coronary vessels were strongly correlated (RCA and LAD R = 0.67 (p < 0.0001), RCA and LCx R = 0.58 (p < 0.0001), LAD and LCx R = 0.67 (p < 0.0001)). The FAIs of each coronary vessel between the patient's first and last CCTA completed at 120 kV were also correlated (RCA R = 0.73 (p < 0.0001), LAD R = 0.81 (p < 0.0001), LCx R = 0.55 (p = 0.0069). Finally, a high mean FAI value of all three coronary vessels at baseline (mean ≥ - 71 HU) was predictive of cardiac mortality or re-transplantation, however, not predictive of all cause-mortality. CONCLUSION: High baseline FAI values may identify a higher-risk cardiac transplant population; thus, FAI may support the implementation of CCTA in post-transplant surveillance. KEY POINT: • Perivascular fat attenuation measured with coronary CT is feasible in cardiac transplant patients and may predict cardiac mortality or need for re-transplantation.

Effect of etelcalcetide versus alfacalcidol on left ventricular function and feature-tracking cardiac magnetic resonance imaging in hemodialysis-a post-hoc analysis of a randomized, controlled trial.

BACKGROUND: Calcimimetic therapy with etelcalcetide (ETEL) has been shown to attenuate the advancement of left ventricular (LV) hypertrophy in hemodialysis patients measured by cardiac magnetic resonance (CMR). The aim of the study was to evaluate whether this effect is accompanied by alterations in LV function and myocardial composition. METHODS: This was a post-hoc analysis of a randomized-controlled trial of ETEL versus Alfacalcidol (ALFA) in 62 hemodialysis patients. LV function was assessed using LV ejection fraction (LVEF) and LV global longitudinal strain (GLS) on feature-tracking (FT) CMR. Myocardial tissue characteristics were analyzed using parametric T1 and T2 mapping. RESULTS: Of the total study cohort (n = 62), 48 subjects completed both CMR scans with sufficient quality for FT analysis. In the one-year follow-up, LV GLS deteriorated in the ALFA group, whereas the ETEL group remained stable (LV GLS change: + 2.6 ± 4.6 versus + 0.3 ± 3.8; p = 0.045 when adjusting for randomization factors and baseline LV GLS). We did not observe a difference in the change of LVEF between the two groups (p = 0.513). The impact of ETEL treatment on LV GLS over time remained significant after additional adjustment for the change in LV mass during the study period. ETEL treatment did not significantly affect other CMR parameters. There were no changes in myocardial composition between treatment groups (T1 time change: + 15 ± 42 versus + 10 ± 50; p = 0.411; T2 time change: - 0.13 ± 2.45 versus - 0.70 ± 2.43; p = 0.652). CONCLUSIONS: In patients undergoing hemodialysis, treatment with ETEL was protective against deterioration of LV longitudinal function, as evaluated through FT CMR, when compared to the control therapy of ALFA. This effect was not mediated by the change in LV mass. Trial registration URL: https://clinicaltrials.gov/ct2/show/NCT03182699 . Unique identifier: NCT03182699.

Detection of sympathetic denervation defects in Fabry disease by hybrid [11C]meta-hydroxyephedrine positron emission tomography and cardiac magnetic resonance.

BACKGROUND: Myocardial glycosphingolipid accumulation in patients with Fabry disease (FD) causes biochemical and structural changes. This study aimed to investigate sympathetic innervation in FD using hybrid cardiac positron emission tomography (PET)/magnetic resonance imaging (MRI). METHODS AND RESULTS: Patients with different stages of Fabry disease were prospectively enrolled to undergo routine CMR at 1.5T, followed by 3T hybrid cardiac PET/MRI with [11C]meta-hydroxyephedrine ([11C]mHED). Fourteen patients with either no evidence of cardiac involvement (n = 5), evidence of left ventricular hypertrophy (LVH) (n = 3), or evidence of LVH and fibrosis via late gadolinium enhancement (LGE) (n = 6) were analyzed. Compared to patients without LVH, patients with LVH or LVH and LGE had lower median T1 relaxation times (ms) at 1.5 T (1007 vs. 889 vs. 941 ms, p = 0.003) and 3T (1290 vs. 1172 vs. 1184 p = .014). Myocardial denervation ([11C]mHED retention < 7%·min) was prevalent only in patients with fibrosis, where a total of 16 denervated segments was found in two patients. The respective area of denervation exceeded the area of LGE in both patients (24% vs. 36% and 4% vs. 32%). However, sympathetic innervation defects ([11C]mHED retention ≤ 9%·min) occurred in all study groups. Furthermore, a reduced sympathetic innervation correlated with an increased left ventricular mass (p = .034, rs = - 0.57) and a reduced global longitudinal strain (GLS) (p = 0.023, rs = - 0.6). CONCLUSION: Hybrid cardiac PET/MR with [11C]mHED revealed sympathetic innervation defects, accompanied by impaired GLS, in early stages of Fabry disease. However, denervation is only present in patients with advanced stages of FD showing fibrosis on CMR.

Preprocedural imaging modalities in patients undergoing iliocaval venous recanalization and stent placement.

PURPOSE: To determine the diagnostic accuracy of preinterventional imaging modalities in patients being evaluated for iliocaval venous recanalization and stent placement. METHODS: Consecutive patients with iliocaval postthrombotic obstructions or nonthrombotic iliac vein lesions (NIVL), who were scheduled for recanalization, underwent duplex ultrasound (DUS), magnetic resonance venography (MRV), multiplanar venography (MPV), and intravascular ultrasound (IVUS). The diagnostic accuracies of DUS, MRV, and MPV were analyzed using IVUS as reference. RESULTS: A total of 216 limbs in 108 patients (80 patients with postthrombotic obstructions, 28 patients with NIVL) were examined. In patients with postthrombotic obstructions, the diagnostic sensitivities for the detection of lesions of the common femoral vein were 81% (95% CI 71-89%) for DUS, 76% (95% CI 65-85%) for MRV, and 86% (95% CI 76-93%) for MPV. The sensitivities for detecting lesions of the iliac veins were 96% (95% CI 89-99%) for DUS, 99% (95% CI 92-100%) for MRV, and 100% (95% CI 94-100%) for MPV. Regarding the inferior vena cava, the sensitivities were 44% (95% CI 24-65%) for DUS, 52% (95% CI 31-73%) for MRV, and 70% (95% CI 47-86%) for MPV. The sensitivities for detecting NIVL were 58% (95% CI 34-79%) for DUS, 90% (95% CI 68-97%) for MRV, and 95% (95% CI 73-99%) for MPV. CONCLUSION: In patients scheduled for recanalization of iliocaval postthrombotic obstructions, the sensitivities of DUS, MRV, and MPV were similar. In patients with suspected inferior vena cava involvement and in patients with NIVL, additional imaging with MR or conventional venography is required.

Bioimpedance Spectroscopy Reveals Important Association of Fluid Status and T1 -Mapping by Cardiovascular Magnetic Resonance.

BACKGROUND: Extracellular matrix expansion is a key pathophysiologic feature in heart failure and can be quantified noninvasively by cardiac magnetic resonance T1 -mapping. Free water within the interstitial space of the myocardium, however, may also alter T1 -mapping results. PURPOSE: To investigate the association between systemic fluid status and T1 -mapping by cardiac magnetic resonance. STUDY TYPE: Prospective, observational single-center study. POPULATION: Two-hundred eighty-five consecutive patients (44.4% female, 70.0 ± 14.9 years old) scheduled for cardiac MR due to various cardiac diseases. SEQUENCE AND FIELD STRENGTH: 1.5-T scanner (Avanto Fit, Siemens Healthineers, Erlangen, Germany). For T1 -mapping, electrocardiographically triggered modified-Look-Locker inversion (MOLLI) recovery sequence using a 5(3)3 prototype on a short-axis mid-cavity slice and with a four-chamber view was performed. ASSESSMENTS: MR parameters including native myocardial T1 -times using MOLLI and extracellular volume (MR-ECV) were assessed, and additionally, we performed bioimpedance analysis (BIA). Furthermore, demographic data and comorbidities were assessed. STATISTICS: Wilcoxon's rank-sum test, chi-square tests, and for correlation analysis, Pearson's correlation coefficients were used. Regression analyses were performed to investigate the association between patients' fluid status and T1 -mapping results. A P-value <0.05 was considered statistically significant. RESULTS: The mixed cohort presented with a mean overhydration (OH) of +0.2 ± 2.4 liters, as determined by BIA. By MR, native T1 -times were 1038 ± 51 msec and MR-ECV was 31 ± 9%. In the multivariable regression analysis, only OH was significantly associated with MR-ECV (adj. beta: 0.711; 95% CI: 0.28 to 1.14) along with male sex (adj. beta: 2.529; 95% CI: 0.51 to 4.55). In linear as well as multivariable analysis, only OH was significantly associated with native T1 times (adj. beta: 3.750; 95% CI: 1.27 to 6.23). CONCLUSION: T1 -times and MR-ECV were significantly associated with the degree of OH on BIA measurement. These effects were independent from age, sex, body mass index, and hematocrit. Patients' volume status may thus be an important factor when T1 -time and MR-ECV values are interpreted. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 3.

Closure of Post-thrombotic Iliac Arteriovenous Fistulas by Iliac Vein Recanalization.

PURPOSE: The purpose of this study was to report the closure of iliac arteriovenous fistulas associated with a post-thrombotic iliac vein occlusion by iliac venous stent recanalization. CASE REPORT: An 80-year-old woman presented with a worsening painful swelling of her left leg after an iliofemoral deep vein thrombosis 6 months ago. Duplex ultrasound and magnetic resonance venography revealed a post-thrombotic obstruction of her iliac veins as well as several arteriovenous fistulas between branches of her left external and internal iliac arteries and adjacent diseased venous segments. In a first attempt, coil embolization did not sustainably close these iliac arteriovenous fistulas. Direct stent recanalization of the chronically diseased iliofemoral venous segment, however, resulted in an immediate closure of arteriovenous shunt flow and subsequent improvement of clinical symptoms. Six months after iliac vein stent recanalization, still no fistulas could be detected any more, venous stents were fully patent, and the patient was free of symptoms. CONCLUSION: Post-thrombotic iliofemoral obstructions might be associated with the development of arteriovenous fistulas. Direct stent recanalization of the chronically occluded veins results in closure of related arteriovenous fistulas. CLINICAL IMPACT: This case suggests that the combined occurrence of post-thrombotic venous obstructions with arteriovenous fistulas, which are related to aforementioned venous lesions, should be evaluated for primary venous stent recanalization rather than fistula embolization.

Accuracy of PET quantification in [68Ga]Ga-pentixafor PET/MR imaging of carotid plaques.

AIM: The aim of this study was to evaluate and correct for partial-volume-effects (PVE) on [68Ga]Ga-Pentixafor uptake in atherosclerotic plaques of the carotid arteries, and the impact of ignoring bone in MR-based attenuation correction (MR-AC). METHODS: Twenty [68Ga]Ga-pentixafor PET/MR examinations including a high-resolution T2-TSE MR of the neck were included in this study. Carotid plaques located at the carotid bifurcation were delineated and the anatomical information was used for partial-volume-correction (PVC). Mean and max tissue-to-background ratios (TBR) of the [68Ga]Ga-Pentixafor uptake were compared for standard and PVC-PET images. A potential influence of ignoring bone in MR-AC was assessed in a subset of the data reconstructed after incorporating bone into MR-AC and a subsequent comparison of standardized-uptake values (SUV). RESULTS: In total, 34 atherosclerotic plaques were identified. Following PVC, mean and max TBR increased by 77 and 95%, respectively, when averaged across lesions. When accounting for bone in the MR-AC, SUV of plaque changed by 0.5%. CONCLUSION: Quantitative readings of [68Ga]Ga-pentixafor uptake in plaques are strongly affected by PVE, which can be reduced by PVC. Including bone information into the MR-AC yielded no clinically relevant effect on tracer quantification.

Assessment of left and right ventricular functional parameters using dynamic dual-tracer [13N]NH3 and [18F]FDG PET/MRI.

BACKGROUND: Cardiac positron emission tomography/magnetic resonance imaging (PET/MRI) can assess various cardiovascular diseases. In this study, we intra-individually compared right (RV) and left ventricular (LV) parameters obtained from dual-tracer PET/MRI scan. METHODS: In 22 patients with coronary heart disease (69 ± 9 years) dynamic [13N]NH3 (NH3) and [18F]FDG (FDG) PET scans were acquired. The first 2 minutes were used to calculate LV and RV first-pass ejection fraction (FPEF). Additionally, LV end-systolic (LVESV) and end-diastolic (LVEDV) volume and ejection fraction (LVEF) were calculated from the early (EP) and late-myocardial phases (LP). MRI served as a reference. RESULTS: RVFPEF and LVFPEF from FDG and NH3 as well as RVEF and LVEF from MRI were (28 ± 11%, 32 ± 15%), (32 ± 11%, 41 ± 14%) and (42 ± 16%, 45 ± 19%), respectively. LVESV, LVEDV and LVEF from EP FDG and NH3 in 8 and 16 gates were [71 (15 to 213 mL), 98 (16 to 241 mL), 32 ± 17%] and [50 (17 to 206 mL), 93 (13 to 219 mL), 36 ± 17%] as well as [60 (19 to 360 mL), 109 (56 to 384 mL), 41 ± 22%] and [54 (16 to 371 mL), 116 (57 to 431 mL), 46 ± 24%], respectively. Moreover, LVESV, LVEDV and LVEF acquired from LP FDG and NH3 were (85 ± 63 mL, 138 ± 63 mL, 47 ± 19%) and (79 ± 56 mL, 137 ± 63 mL, 47 ± 20%), respectively. The LVESV, LVEDV from MRI were 93 ± 66 mL and 153 ± 71 mL, respectively. Significant correlations were observed for RVFPEF and LVFPEF between FDG and MRI (R = .51, P = .01; R = .64, P = .001), respectively. LVESV, LVEDV, and LVEF revealed moderate to strong correlations to MRI when they acquired from EP FDG and NH3 in 16 gates (all R > .7, P = .000). Similarly, all LV parameters from LP FDG and NH3 correlated good to strongly positive with MRI (all R > .7, and P < .001), except EDV from NH3 weakly correlated to EDV of MRI (R = .54, P < .05). Generally, Bland-Altman plots showed good agreements between PET and MRI. CONCLUSIONS: Deriving LV and RV functional values from various phases of dynamic NH3 and FDG PET is feasible. These results could open a new perspective for further clinical applications of the PET examinations.

Inflow cannula position as risk factor for stroke in patients with HeartMate 3 left ventricular assist devices.

BACKGROUND: A relation between the left ventricular assist device inflow cannula (IC) malposition and pump thrombus has been reported. This study aimed to investigate if the pump position, derived from chest X-rays in HeartMate 3 (HM3) patients, correlates with neurological dysfunction (ND), ischemic stroke (IS), hemorrhagic stroke (HS) and survival. METHODS: This analysis was performed on routinely acquired X-rays of 42 patients implanted with a HM3 between 2014 and 2017. Device position was quantified in patients with and without ND from frontal and lateral X-rays characterizing the IC and pump in relation to spine, diaphragm or horizontal line. The primary end-point was freedom from stroke and survival one-year after HM3 implantation stratified by pump position. RESULTS: The analysis of X-rays, 33.5 (41.0) days postoperative, revealed a significant smaller IC angle of HM3 patients with ND versus no ND (0.1° ± 14.0° vs. 12.9° ± 10.1°, p = 0.005). Additionally, the IC angle in the frontal view, IS: 4.1 (20.9)° versus no IS: 13.8 (7.5)°, p = 0.004 was significantly smaller for HM3 patients with IS. Using receiver operating characteristics derived cut-off, IC angle <10° provided 75% sensitivity and 100% specificity (C-statistic = 0.85) for predicting IS. Stratified by IC angle, freedom from IS at 12 months was 100% (>10°) and 60% (<10°) respectively (p = 0.002). No significant differences were found in any end-point between patients with and without HS. One-year survival was significantly higher in patients with IC angle >10° versus <10° (100% vs. 71.8%, p = 0.012). CONCLUSIONS: IC malposition derived from standard chest X-rays serves as a risk factor for ND, IS and worse survival in HM3 patients.

Safety and image quality of cardiovascular magnetic resonance imaging in patients with retained epicardial pacing wires after heart transplantation.

BACKGROUND: Temporary epicardial pacing wires, implemented in patients during heart transplantation, are routinely removed before discharge. However, in some cases, these wires may remain in situ and are often considered as a contraindication for cardiovascular magnetic resonance (CMR) imaging in the future. Therefore, we aimed to provide data about safety and image quality of CMR in these patients. METHODS: This is a report on a subpopulation out of 88 patients after heart transplantation that were included in a prospective cohort study and underwent multiple CMR in their post-transplant course. During CMR, patients were monitored by electrocardiogram and all examinations were observed by a physician to document potential adverse events. Additionally, image quality was assessed by an imaging specialist. RESULTS: Nineteen of 88 patients included had temporary pacing wires in situ. These patients underwent a total of 51 CMR studies. No major adverse event and only one single, mild sensory event could be documented. All CMR studies showed preserved diagnostic image quality. Temporary pacing wires were visible in 100% of HASTE and cine sequences. In less than 50% of the examinations, temporary pacing wires were also visible in T1 and T2 mapping, short tau inversion recovery (STIR), and late gadolinium enhancement (LGE) sequences, without any impairment of image quality. CONCLUSIONS: With a low event rate of only one mild adverse event during 51 CMR examinations (2%), CMR appears to be safe in patients with retained temporary epicardial pacing wires after heart transplantation. Moreover, image quality was not impaired by the presence of pacing wires.

[Acute and chronic cardiac involvement in COVID-19]. / Akute und chronische kardiale Beteiligung bei COVID-19.

BACKGROUND: Infections with coronavirus disease 2019 (COVID-19) most frequently affect the lungs but may also result in cardiovascular involvement and cardiovascular complications. The heart can either be involved as part of a systemic infection or directly involved due to myocarditis or pericarditis as well as in hypoxia, volume overload, fever or thromboembolic complications. Moreover, pre-existing underlying cardiovascular diseases have a substantial influence on the prognosis of patients with COVID-19 infections. METHOD: This review article is based on a comprehensive literature search in the PubMed database on cardiac involvement and cardiac complications of COVID 19 infections, enriched by experiences in dealing with this disorder. RESULTS AND CONCLUSION: Depending on the severity of the infection, cardiac involvement in a COVID 19 infection is observed in up to 50% of the patients. Besides echocardiography as the first-line examination method, cardiac magnetic resonance imaging (MRI) for assessment of the myocardial structure and cardiac computed tomography (CT) for assessment of coronary arteries and to rule out intracardiac thrombus formation represent important imaging modalities. The most important cardiac manifestations in COVID 19 infections are ischemic and inflammatory diseases. The imaging diagnostics play an important role in the acute as well as in the postinfectious phases.

Feature Tracking of Global Longitudinal Strain by Using Cardiovascular MRI Improves Risk Stratification in Heart Failure with Preserved Ejection Fraction.

Background In heart failure with preserved ejection fraction (HFpEF), echocardiographic studies suggest that global longitudinal strain (GLS) has an impact on survival. Feature-tracking cardiovascular MRI also allows for strain analysis; however, to the knowledge of the authors, little is known about its prognostic value and whether it reflects severity of diffuse fibrosis, as assessed by cardiovascular MRI T1 mapping. Purpose To investigate the association between myocardial strain at cardiovascular MRI with extracellular volume by T1 mapping and outcome in participants with HFpEF. Materials and Methods In this secondary analysis of a prospective study (NCT03405987), consecutive participants with HFpEF underwent cardiovascular MRI between July 2012 and March 2018, including T1 mapping and three-dimensional strain analysis. Extracellular volume and strain results were assessed to determine if there was a correlation between these two factors. Cox regression was performed to determine the prognostic relevance of MRI-derived myocardial strain for a combined end point (events) of heart failure hospitalizations and cardiovascular death. Results In total, 206 consecutive participants with HFpEF (mean age, 71 years ± 8 [standard deviation]; 69% women) were included. Median myocardial global longitudinal strain (GLS) at MRI was -8.5% and showed low correlation with extracellular volume (r = 0.28; P = .003). A total of 109 events (53%) were recorded during a follow-up of 38 months ± 29. Participants with a GLS above the median had higher event rates (log-rank test, P < .001). By multivariable Cox regression analysis, GLS remained independently associated with outcome (hazard ratio, 1.06 per 1% strain increase; 95% confidence interval: 1.01, 1.11; P = .03) when corrected for risk factors including age, diabetes, renal function, N-terminal pro-b-type natriuretic peptide serum concentration, and right ventricular size and function. Conclusion In participants with heart failure with preserved ejection fraction, global longitudinal strain at cardiovascular MRI was correlated with extracellular volume by T1 mapping and was associated with cardiovascular events. © RSNA, 2020 Online supplemental material is available for this article.

Data-driven, projection-based respiratory motion compensation of PET data for cardiac PET/CT and PET/MR imaging.

BACKGROUND: Respiratory patient motion causes blurring of the PET images that may impact accurate quantification of perfusion and infarction extents in PET myocardial viability studies. In this study, we investigate the feasibility of correcting for respiratory motion directly in the PET-listmode data prior to image reconstruction using a data-driven, projection-based, respiratory motion compensation (DPR-MoCo) technique. METHODS: The DPR-MoCo method was validated using simulations of a XCAT phantom (Biograph mMR PET/MR) as well as experimental phantom acquisitions (Biograph mCT PET/CT). Seven patient studies following a dual-tracer (18F-FDG/13N-NH3) imaging-protocol using a PET/MR-system were also evaluated. The performance of the DPR-MoCo method was compared against reconstructions of the acquired data (No-MoCo), a reference gate method (gated) and an image-based MoCo method using the standard reconstruction-transform-average (RTA-MoCo) approach. The target-to-background ratio (TBRLV) in the myocardium and the noise in the liver (CoVliver) were evaluated for all acquisitions. For all patients, the clinical effect of the DPR-MoCo was assessed based on the end-systolic (ESV), the end-diastolic volumes (EDV) and the left ventricular ejection fraction (EF) which were compared to functional values obtained from the cardiac MR. RESULTS: The DPR-MoCo and the No-MoCo images presented with similar noise-properties (CoV) (P = .12), while the RTA-MoCo and reference-gate images showed increased noise levels (P = .05). TBRLV values increased for the motion limited reconstructions when compared to the No-MoCo reconstructions (P > .05). DPR-MoCo results showed higher correlation with the functional values obtained from the cardiac MR than the No-MoCo results, though non-significant (P > .05). CONCLUSION: The projection-based DPR-MoCo method helps to improve PET image quality of the myocardium without the need for external devices for motion tracking.

The influence of left ventricular assist device inflow cannula position on thrombosis risk.

The use of left ventricular assist devices (LVADs) as a treatment method for heart failure patients has been steadily increasing; however, pathological studies showed presence of thrombi around the HeartWare ventricular assist device inflow cannula (IC) in more than 95% of patients after device explantation. Flow fields around the IC might trigger thrombus formation and require further investigation. In this study flow dynamics parameters were evaluated for different patient geometries using computational fluid dynamics (CFD) simulations. Left ventricular (LV) models of two LVAD patients were obtained from CT scans. The LV volumes of Patient 1 (P1) and Patient 2 (P2) were 264 and 114 cm3 with an IC angle of 20° and 9° from the mitral-IC tip axis at the coronal plane. The IC insertion site at the apex was central for P1, whereas it was lateral for P2. Transient CFD simulations were performed over 9 cardiac cycles. The wedge area was defined from the cannula tip to the wall of the LV apex. Mean velocity magnitude and blood stagnation region (volume with mean velocity <5 mm/s) as well as the wall shear stress (WSS) at the IC surface were calculated. Cardiac support resulted in a flow mainly crossing the ventricle from the mitral valve to the LVAD cannula for P2, while the main inflow jet deviated toward the septal wall in P1. Lower WSS at the IC surface and consequently larger stagnation volumes were observed for P2 (P1: 0.17, P2: 0.77 cm3 ). Flow fields around an LVAD cannula can be influenced by many parameters such as LV size, IC angle, and implantation site. Careful consideration of influencing parameters is essential to get reliable evaluations of the apical flow field and its connection to apical thrombus formation. Higher blood washout and lower stagnation were observed for a central implantation of the IC at the apex.

Thoracic endovascular repair for acute complicated type B aortic dissections.

OBJECTIVE: This study retrospectively assessed in-hospital mortality and long-term results of emergency thoracic endovascular aortic repair (TEVAR) for patients with life-threatening acute complicated type B aortic dissection (acTBD). METHODS: Between March 2001 and December 2016, there were 55 patients (40 male; median age, 52 ± 13 years) with an acTBD who were treated with TEVAR for malperfusion (58%), aortic rupture (18%), or persistent untreatable pain with true lumen reduction or rapid aortic diameter enlargement (24%) as a sign of disease progression. The patients were categorized according to clinical appearance into two groups: group A, malperfusion, pending rupture, or rupture; and group B, persistent ongoing pain, rapid enlargement of aortic diameter, or significant changes in the true to false lumen ratio. Four patients (7%) had undergone previous aortic surgery. RESULTS: Technical success (coverage of the primary intimal tear) was achieved in 50 patients (91%). The overall in-hospital mortality rate was 9% (n = 5), and there was a statistically significant difference in early mortality between group A and group B (7% vs 2%; P < .02). Causes of in-hospital death were all aorta related, including a rupture during the procedure and on the first postinterventional day in two patients and redissection (ascending aorta, n = 2; descending aorta, n = 1) with a consequent aortic rupture after TEVAR in the remaining three. Permanent neurologic dysfunction occurred in five patients (stroke, n = 2; paraplegia, n = 3). Overall, 19 patients (34%) developed early endoleaks (type IA, n = 5; type IB, n = 11; type II, n = 2; type IB plus type II, n = 1). Therefore, 5 patients needed early (within 30 days) endovascular intervention because of a type IA (n = 2), type IB (n = 3), or type II endoleak (n = 1) and the rapid progression of aortic diameter, persistent signs of ischemia (n = 2), or rupture (n = 1), whereas the remaining 14 patients were treated conservatively and followed up by computed tomography angiography. Seven patients with early endoleaks needed an endovascular intervention (n = 3) or conventional surgery (n = 4) because of aortic progression in the follow-up period (mean interval after procedure, 92 ± 56 months). The actual survival rates were 87%, 85%, and 75% at 1 year, 2 years, and 5 years, respectively, and freedom from aorta-related death was 87%, 87%, and 77% at 1 year, 2 years, and 5 years, respectively. Freedom from reintervention for any cause using a Kaplan-Meier analysis was 70%, 68%, 68%, and 63% at 6 months, 1 year, 2 years, and 5 years, respectively. CONCLUSIONS: TEVAR of acTBD has been proven to be an excellent treatment modality in this cohort of high-risk patients, with promising midterm and long-term results.

[68Ga]Pentixafor PET/MR imaging of chemokine receptor 4 expression in the human carotid artery.

PURPOSE: Type 4 chemokine receptor (CXCR4) plays an important role in immune cell migration during the atherosclerosis progression. We aimed to evaluate [68Ga]Pentixafor positron emission tomography (PET) in combination magnetic resonance imaging (MRI) for in vivo quantification of CXCR4 expression in carotid plaques. METHODS: Seventy-two patients with lymphoma were prospectively scheduled for whole body [68Ga]Pentixafor PET/MRI with an additional T2-weighted carotid sequence. Volumes of interest (VOIs) were drawn along the carotid bifurcation regions, and the maximum tissue-to-blood ratios (TBR) of [68Ga]Pentixafor uptake were calculated. Lesions were categorized into non-eccentric (n = 27), mild eccentric (n = 67), moderately (n = 41) and severely (n = 19) eccentric carotid atherosclerosis. A different cohort of symptomatic patients (n = 10) with carotid stenosis scheduled for thrombendarterectomy (TEA) was separately imaged with 3T MRI with dedicated plaque sequences (time of flight, T1-, and T2-weighted). MRI findings were correlated with histochemical assessment of intact carotid plaques. RESULTS: At hybrid PET/MRI, we observed significantly increased [68Ga]Pentixafor uptake in mildly (mean TBRmax = 1.57 ± 0.27, mean SUVmax = 2.51 ± 0.39), moderately (mean TBRmax = 1.64 ± 0.37, mean SUVmax = 2.61 ± 0.55) and severely eccentric carotids (mean TBRmax = 1.55 ± 0.26, mean SUVmax = 2.40 ± 0.44) as compared to non-eccentric carotids (mean TBRmax = 1.29 ± 0.21, mean SUVmax = 1.77 ± 0.42) (p ≤ 0.05). Histological findings from TEA confirmed that prominent CXCR4 expression was localized within inflamed atheromas and preatheromas. Co-localization of cellular CXCR4 and CD68 expression in the plaque was observed by immunofluorescence staining. CONCLUSIONS: In vivo evaluation of CXCR4 expression in carotid atherosclerotic lesions is feasible using [68Ga]Pentixafor PET/MRI. In atherosclerotic plaque tissue, CXCR4 expression might be used as a surrogate marker for inflammatory atherosclerosis.

Assessment of sympathetic reinnervation after cardiac transplantation using hybrid cardiac PET/MRI: A pilot study.

BACKGROUND: Sympathetic reinnervation after heart transplantation (HTX) is a known phenomenon, which has an impact on patient heart rate variability and exercise capacity. The impact of reinnervation on myocardial structure has not been evaluated yet. PROPOSE: To evaluate the feasibility of simultaneous imaging of cardiac reinnervation and cardiac structure using a hybrid PET/MRI system. STUDY TYPE: Prospective / pilot study. SUBJECTS: Ten patients, 4-21 years after cardiac transplantation. FIELD STRENGTH/SEQUENCE: 3 T hybrid PET/MRI system. Cine SSFP, T1 mapping (modified Look-Locker inversion recovery sequence) pre/postcontrast as well as dynamic [11 C]meta-hydroxyephedrine ([11 C]mHED) PET. ASSESSMENT: All MRI and PET parameters were evaluated by experienced readers using dedicated postprocessing software packages for cardiac MRI and PET. For all parameters a 16-segment model for the left ventricle was applied. STATISTICAL TESTS: Mann-Whitney U-test; Spearman correlations. RESULTS: Thirty-six of 160 myocardial segments showed evidence of reinnervation by PET. On a segment-based analysis, mean native T1 relaxation times were nonsignificantly altered in segments with evidence of reinnervation (1305 ± 151 msec vs. 1270 ± 112 msec; P = 0.1), whereas mean extracellular volume (ECV) was significantly higher in segments with evidence of reinnervation (35.8 ± 11% vs. 30.9 ± 7%; P = 0.019). There were no significant differences in wall motion (WM) and wall thickening (WT) between segments with or without reinnervation (mean WM: 7.6 ± 4 mm vs. group B: 9.3 ± 7 mm [P = 0.13]; WT: 79 ± 63% vs. 94 ± 74% [P = 0.27]) under resting conditions. DATA CONCLUSION: The assessment of cardiac reinnervation using a hybrid PET/MRI system is feasible. Segments with evidence of reinnervation by PET showed nonsignificantly higher T1 relaxation times and a significantly higher ECV, suggesting a higher percentage of diffuse fibrosis in these segments, without impairment of rest WM and WT. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:1326-1335.