ObjectivesCardiac magnetic resonance (CMR) was used to investigate the extracellular compartment and myocardial fibrosis in patients with aortic stenosis, as well as their association with other measures of left ventricular decompensation and mortality.BackgroundProgressive myocardial fibrosis drives the transition from hypertrophy to heart failure in aortic stenosis. Diffuse fibrosis is associated with extracellular volume expansion that is detectable by T1 mapping, whereas late gadolinium enhancement (LGE) detects replacement fibrosis.MethodsIn a prospective observational cohort study, 203 subjects (166 with aortic stenosis [69 years; 69% male]; 37 healthy volunteers [68 years; 65% male]) underwent comprehensive phenotypic characterization with clinical imaging and biomarker evaluation. On CMR, we quantified the total extracellular volume of the myocardium indexed to body surface area (iECV). The iECV upper limit of normal from the control group (22.5 ml/m2) was used to define extracellular compartment expansion. Areas of replacement mid-wall LGE were also identified. All-cause mortality was determined during 2.9 ± 0.8 years of follow up.ResultsiECV demonstrated a good correlation with diffuse histological fibrosis on myocardial biopsies (r = 0.87; p < 0.001; n = 11) and was increased in patients with aortic stenosis (23.6 ± 7.2 ml/m2 vs. 16.1 ± 3.2 ml/m2 in control subjects; p < 0.001). iECV was used together with LGE to categorize patients with normal myocardium (iECV <22.5 ml/m2; 51% of patients), extracellular expansion (iECV ≥22.5 ml/m2; 22%), and replacement fibrosis (presence of mid-wall LGE, 27%). There was evidence of increasing hypertrophy, myocardial injury, diastolic dysfunction, and longitudinal systolic dysfunction consistent with progressive left ventricular decompensation (all p < 0.05) across these groups. Moreover, this categorization was of prognostic value with stepwise increases in unadjusted all-cause mortality (8 deaths/1,000 patient-years vs. 36 deaths/1,000 patient-years vs. 71 deaths/1,000 patient-years, respectively; p = 0.009).ConclusionsCMR detects ventricular decompensation in aortic stenosis through the identification of myocardial extracellular expansion and replacement fibrosis. This holds major promise in tracking myocardial health in valve disease and for optimizing the timing of valve replacement. (The Role of Myocardial Fibrosis in Patients With Aortic Stenosis; NCT01755936)

Background Acute stress induced (takotsubo) cardiomyopathy can result in a heart failure phenotype with a prognosis comparable to myocardial infarction. In this study, we hypothesized that inflammation is central to the pathophysiology and natural history of takotsubo cardiomyopathy. Methods In a multi-centre study, we prospectively recruited 55 patients with takotsubo cardiomyopathy and 51 age, sex and co-morbidity matched control subjects. During the index event and at 5 months follow-up, patients with takotsubo cardiomyopathy underwent multiparametric cardiac magnetic resonance imaging including ultrasmall superparamagnetic particles of iron oxide (USPIO) enhancement for detection of inflammatory macrophages in the myocardium. Blood monocyte subpopulations and serum cytokines were assessed as measures of systemic inflammation. Matched controls underwent investigation at a single time point. Results Subjects were predominantly middle aged (64±14years) women (90%). When compared to control subjects, patients with takotsubo cardiomyopathy had greater USPIO enhancement (expressed as the difference between pre-USPIO and post-USPIO T2*) in both ballooning (14.3±0.6 versus 10.5±0.9 ms, p<0.001) and non-ballooning (12.9±0.6 versus 10.5±0.9 ms, p=0.02) left ventricular myocardial segments. Serum interleukin-6 (23.1±4.5 versus 6.5±5.8 pg/mL, p< 0.001) and chemokine (C-X-C motif) ligand 1 (1903±168 versus 1272±177 pg/mL, p=0.01) concentrations, and classical CD14++CD16- monocytes (90±0.5 versus 87±0.9%, p=0.01) were also increased whilst intermediate CD14++CD16+ (5.4±0.3 versus 6.9±0.6%, p=0.01) and non-classical CD14+CD16++ (2.7±0.3% versus 4.2±0.5%, p=0.006) monocytes were reduced in patients with takotsubo cardiomyopathy. At 5 months, USPIO enhancement was no longer detectable in the left ventricular myocardium although there remained persistent elevations in serum interleukin-6 concentrations (p=0.009) and reductions in intermediate CD14++CD16+ monocytes (5.6±0.4 versus 6.9±0.6%, p=0.01). Conclusions We demonstrate for the first time that takotsubo cardiomyopathy is characterized by a myocardial macrophage inflammatory infiltrate, changes in the distribution of monocyte subsets and an increase in systemic pro-inflammatory cytokines. Many of these changes persisted for at least 5 months suggesting a low-grade chronic inflammatory state.

Background-Abdominal aortic aneurysms are a major cause of death. Prediction of aneurysm expansion and rupture is challenging and currently relies on the simple measure of aneurysm diameter. Using MRI, we aimed to assess whether areas of cellular inflammation correlated with the rate of abdominal aortic aneurysm expansion. Methods and Results-Stable patients (nϭ29; 27 male; age, 70Ϯ5 years) with asymptomatic abdominal aortic aneurysms (4.0 to 6.6 cm) were recruited from a surveillance program and imaged using a 3-T MRI scanner before and 24 to 36 hours after administration of ultrasmall superparamagnetic particles of iron oxide (USPIO). The change in T2* value on T2*-weighted imaging was used to detect accumulation of USPIO within the abdominal aortic aneurysm. Histological examination of aneurysm tissue confirmed colocalization and uptake of USPIO in areas with macrophage infiltration. Patients with distinct mural uptake of USPIO had a 3-fold higher growth rate (nϭ11, 0.66 cm/y; Pϭ0.020) than those with no (nϭ6, 0.22 cm/y) or nonspecific USPIO uptake (nϭ8, 0.24 cm/y) despite having similar aneurysm diameters (5.4Ϯ0.6, 5.1Ϯ0.5, and 5.0Ϯ0.5 cm, respectively; PϾ0.05). In 1 patient with an inflammatory aneurysm, there was a strong and widespread uptake of USPIO extending beyond the aortic wall. Conclusions-Uptake of USPIO in abdominal aortic aneurysms identifies cellular inflammation and appears to distinguish those patients with more rapidly progressive abdominal aortic aneurysm expansion.

Typically, a medical image offers spatial information on the anatomy (and pathology) modulated by imaging specific characteristics. Many imaging modalities including Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) can be interpreted in this way. We can venture further and consider that a medical image naturally factors into some spatial factors depicting anatomy and factors that denote the imaging characteristics. Here, we explicitly learn this decomposed (disentangled) representation of imaging data, focusing in particular on cardiac images. We propose Spatial Decomposition Network (SDNet), which factorises 2D medical images into spatial anatomical factors and non-spatial modality factors. We demonstrate that this high-level representation is ideally suited for several medical image analysis tasks, such as semi-supervised segmentation, multi-task segmentation and regression, and image-to-image synthesis. Specifically, we show that our model can match the performance of fully supervised segmentation models, using only a fraction of the labelled images. Critically, we show that our factorised representation also benefits from supervision obtained either when we use auxiliary tasks to train the model in a multi-task setting (e.g. regressing to known cardiac indices), or when aggregating multimodal data from different sources (e.g. pooling together MRI and CT data). To explore the properties of the learned factorisation, we perform latent-space arithmetic and show that we can synthesise CT from MR and vice versa, by swapping the modality factors. We also demonstrate that the factor holding image specific information can be used to predict the input modality with high accuracy. Code will be made available at https://github. com/agis85/anatomy_modality_decomposition.

Magnetic resonance imaging (MRI) is ideally suited for the serial examination of the heart because it is noninvasive, does not involve ionizing radiation, and has excellent soft tissue contrast and spatial resolution. Cardiac magnetic resonance, using T2-weighted imaging, has previously been used to detect Background-Inflammation following acute myocardial infarction (MI) has detrimental effects on reperfusion, myocardial remodelling, and ventricular function. Magnetic resonance imaging using ultrasmall superparamagnetic particles of iron oxide can detect cellular inflammation in tissues, and we therefore explored their role in acute MI in humans. Methods and Results-Sixteen patients with acute ST-segment elevation MI were recruited to undergo 3 sequential magnetic resonance scans within 5 days of admission at baseline, 24 and 48 hours following no infusion (controls; n=6) or intravenous infusion of ultrasmall superparamagnetic particles of iron oxide (n=10; 4 mg/kg). T2*-weighted multigradient-echo sequences were acquired and R2* values were calculated for specific regions of interest. In the control group, R2* values remained constant in all tissues across all scans with excellent repeatability (bias of −0.208 s Key Words: myocardial infarction ◼ inflammation ◼ magnetic resonance imaging ◼ ultrasmall superparamagnetic particles of iron oxide