The International Journal of Cardiovascular Imaging

Piechnik, Stefan; Jerosch-Herold, Michael

doi: 10.1007/s10554-017-1235-7pmid: 28849419

Novel tissue biomarkers based on the spin–lattice relaxation time T1, a fundamental property in the theory of magnetic resonance physics, have emerged as a new approach for myocardial tissue characterization with many validated clinical applications. This article is intended as an overview of the physical and physiological mechanisms underlying the interpretation and the accuracy of any practical measurement of T1, or derived biomarkers such as extravascular volume fraction, and also includes a discussion of potential pitfalls. Numerous caveats und knowledge gaps related to the precise interpretation of T1-based biomarkers remain, which are being addressed incrementally through ongoing research. Equally important, further careful standardization will pave the way for a wider clinical translation of these novel T1-based biomarkers of tissue remodeling, which have been well validated for their sensitivity to pathophysiological changes, though for the most part in single-center studies.

Jellis, Christine; Yingchoncharoen, Teerapat; Gai, Neville; Kusunose, Kenya; Popović, Zoran; Flamm, Scott; Kwon, Deborah

doi: 10.1007/s10554-017-1113-3pmid: 28357724

Right ventricular (RV) fibrosis is increasingly recognized as the underlying pathological substrate in a variety of clinical conditions. We sought to employ cardiac magnetic resonance (CMR) techniques of strain imaging and longitudinal relaxation time (T1) mapping to better examine the relationship between RV function and structure. Our aim was to initially evaluate the feasibility of these techniques to evaluate the right ventricle. We then sought to explore the relationship between RV function and underlying fibrosis, along with examining the evolution of RV remodeling according to the amount of baseline fibrosis. Echocardiography was performed in 102 subjects with non-ischemic cardiomyopathy. Right ventricular parameters were assessed including: fractional area change (FAC) and longitudinal strain. The same cohort underwent CMR. Post-contrast T1 mapping was performed as a marker of fibrosis with a Look-Locker technique using inversion recovery imaging. Mid-ventricular post-contrast T1 values of the RV free wall, RV septum and lateral LV were calculated using prototype analysis software. Biventricular volumetric data including ejection fraction was measured by CMR using a cine short axis stack. CMR strain analysis was also performed to assess 2D RV longitudinal and radial strain. Simultaneous biochemical and anthropometric data were recorded. Subjects were followed over a median time of 29 months (IQR 20–37 months) with echocardiography to evaluate temporal change in RV FAC according to baseline post-contrast T1 values. Longitudinal data analysis was performed to adjust for patient loss during follow-up. Subjects (62% men, 51 ± 15 years) had mild to moderately impaired global RV systolic function (RVEF = 39 ± 15%; RVEDV = 187 ± 69 ml; RVESV = 119 ± 68 ml) and moderate left ventricular dysfunction at baseline (LVEF 30 ± 17%). Good correlation was observed between mean LV and RV post-contrast T1 values (r = 0.652, p < 0.001), with similar post-contrast T1 values maintained in both the RV free wall and septum (r = 0.761, p < 0.001). CMR RVEF demonstrated a proportional correlation with echocardiographic measures of RV longitudinal function and CMR RV strain (longitudinal r = −0.449, p = 0.001; radial r = −0.549, p < 0.001). RVEF was related to RV post-contrast T1 values, particularly in those with RV dysfunction (free wall T1 r = 0.259 p = 0.027; septal T1 r = 0.421 p < 0.001). RV strain was also related to RV post-contrast T1 values (r = −0.417, p = 0.002). Linear regression analysis demonstrated strain and post-contrast T1 values to be independently associated with RVEF. Subjects with severe RV dysfunction (CMR RVEF <25%) demonstrated lower RV CMR strain (longitudinal p = 0.018; radial p < 0.001), RV T1 values (free wall p = 0.013; septum <0.001) and RV longitudinal echocardiography parameters despite no difference in afterload. During follow-up, those with RV free wall post-contrast T1 values ≥ 350 ms demonstrated ongoing improvement in FAC (Δ6%), whilst values <350 ms were associated with deterioration in RV function (ΔFAC = −5%) (p = 0.026). CMR provides a comprehensive method by which to evaluate right ventricular function. Post-contrast T1 mapping and CMR strain imaging are technically feasible and provide incremental information regarding global RV function and structure. The proportional relationship between RV function and post-contrast T1 values supports that myocardial fibrosis is a causative factor of RV dysfunction in NICM, irrespective of RV afterload. This same structural milieu also appears integral to the propensity for both positive and negative RV remodeling long-term, suggestive that this is also determined by the degree of underlying RV fibrosis.

Baritussio, A.; Scatteia, A.; Bucciarelli-Ducci, C.

doi: 10.1007/s10554-017-1116-0pmid: 28315985

Cardiovascular magnetic resonance (CMR) is a multi-parametric, multi-planar, non-invasive imaging technique, which allows accurate determination of biventricular function and precise myocardial tissue characterization in a one-stop-shop technique, free from the use of ionizing radiations. Though CMR has been increasingly applied over the last two decades in every-day clinical practice, its widest application has been in the assessment of ischemic cardiomyopathy.

Schmidt, Ehud; Halperin, Henry

doi: 10.1007/s10554-017-1179-ypmid: 28593399

We review the utilization of magnetic resonance imaging methods for classifying atrial tissue properties that act as a substrate for common cardiac arrhythmias, such as atrial fibrillation. We then review state-of-the-art methods for mapping this substrate as a predicate for treatment, as well as methods used to ablate the electrical pathways that cause arrhythmia and restore patients to sinus rhythm.

Podlesnikar, Tomaz; Delgado, Victoria; Bax, Jeroen

doi: 10.1007/s10554-017-1195-ypmid: 28642994

The left ventricular (LV) remodeling process associated with significant valvular heart disease (VHD) is characterized by an increase of myocardial interstitial space with deposition of collagen and loss of myofibers. These changes occur before LV systolic function deteriorates or the patient develops symptoms. Cardiovascular magnetic resonance (CMR) permits assessment of reactive fibrosis, with the use of T1 mapping techniques, and replacement fibrosis, with the use of late gadolinium contrast enhancement. In addition, functional consequences of these structural changes can be evaluated with myocardial tagging and feature tracking CMR, which assess the active deformation (strain) of the LV myocardium. Several studies have demonstrated that CMR techniques may be more sensitive than the conventional measures (LV ejection fraction or LV dimensions) to detect these structural and functional changes in patients with severe left-sided VHD and have shown that myocardial fibrosis may not be reversible after valve surgery. More important, the presence of myocardial fibrosis has been associated with lesser improvement in clinical symptoms and recovery of LV systolic function. Whether assessment of myocardial fibrosis may better select the patients with severe left-sided VHD who may benefit from surgery in terms of LV function and clinical symptoms improvement needs to be demonstrated in prospective studies. The present review article summarizes the current status of CMR techniques to assess myocardial fibrosis and appraises the current evidence on the use of these techniques for risk stratification of patients with severe aortic stenosis or regurgitation and mitral regurgitation.

Gommans, D.; Cramer, G.; Bakker, Jeannette; Dieker, Hendrik-Jan; Michels, Michelle; Fouraux, Michael; Marcelis, Carlo; Verheugt, Freek; Timmermans, Janneke; Brouwer, Marc; Kofflard, Marcel

doi: 10.1007/s10554-017-1252-6

Maragiannis, Dimitrios; Alvarez, Paulino; Ghosn, Mohamad; Chin, Karen; Hinojosa, Jeremy; Buergler, John; Shah, Dipan; Nagueh, Sherif

doi: 10.1007/s10554-017-1214-zpmid: 28748418

We sought to determine the relation between myocardial extracellular volume (ECV), left ventricular (LV) diastolic function, and exercise tolerance in patients with hypertrophic cardiomyopathy (HCM). Forty five HCM patients with an ejection fraction >50% and no previous septal reduction therapy underwent imaging by CMR and transthoracic echocardiography. CMR was used to quantify LV volumes, mass, EF, LA volumes, scar burden, pre and post contrast T1 relaxation times and ECV. Echocardiography was used to measure outflow tract gradients, mitral inflow and annular velocities, circumferential strain, systolic, early and late diastolic strain rates. Exercise duration and peak oxygen consumption were noted. HCM patients had increased native T1 relaxation time and ECV vs. controls [ECV controls: 24.7 (23.2–26.4) vs. HCM: 26.8 (24.6–31.3)%, P = 0.014]. Both parameters were significantly associated with LV diastolic dysfunction, circumferential strain, diastolic strain rate and peak oxygen consumption (r = −0.73, P < 0.001). Compared to controls, HCM patients have significantly longer native T1 relaxation time and higher ECV. These structural changes lead to worse LV global and segmental diastolic function and in turn reduced exercise tolerance.

Huang, Hsiao-Hui; Huang, Chun-Yu; Chen, Chiao-Ning; Wang, Yun-Wen; Huang, Teng-Yi

doi: 10.1007/s10554-017-1216-xpmid: 28733755

Native T1 value is emerging as a reliable indicator of abnormal heart conditions related to myocardial fibrosis. Investigators have extensively used the standardized myocardial segmentation of the American Heart Association (AHA) to measure regional T1 values of the left ventricular (LV) walls. In this paper, we present a fully automatic system to analyze modified Look–Locker inversion recovery images and to report regional T1 values of AHA segments. Ten healthy individuals participated in the T1 mapping study with a 3.0 T scanner after providing informed consent. First, we obtained masks of an LV blood-pool region and LV walls by using an image synthesis method and a layer-growing method. Subsequently, the LV walls were divided into AHA segments by identifying the boundaries of the septal regions and by using a radial projection method. The layer-growing method significantly enhanced the accuracy of the derived myocardium mask. We compared the T1 values that were obtained using manual region of interest selections and those obtained using the automatic system. The average T1 difference of the calculated segments was 4.6 ± 1.5%. This study demonstrated a practical and robust method of obtaining native T1 values of AHA segments in LV walls.

Shang, Yongning; Zhang, Xiaochun; Leng, Weiling; Lei, Xiaotian; Chen, Liu; Liang, Ziwen; Wang, Jian

doi: 10.1007/s10554-017-1213-0pmid: 28721548

The aims of this study were to use cardiovascular magnetic resonance (CMR) cine to assess left atrium (LA) and left ventricle (LV) function and structure in normotensive type 2 diabetes mellitus (T2DM) patients and to identify the most sensitive index of those T2DM-related cardiac changes. Fifty T2DM patients with normotension (25 males, age 54.7 ± 8.7 years, duration of diabetes: 7.5 ± 5.1 years) and 35 controls (16 males, age: 52.2 ± 13.2 years) were prospectively enrolled. All patients were scanned using CMR four- and two-chamber long-axis cine to assess LA and LV structure and function. Normotensive T2DM patients were associated with decreased LA total ejection fraction (EF), passive EF and LV end diastolic volume, normal LA active EF and LV myocardial mass and increased LV mass/volume (M/V). LA total EF and passive EF correlated with body mass index, duration of diabetes and M/V. To differentiate between diabetic patients and healthy controls, area under the receiver operating characteristic (ROC) curve (AUC) values were calculated to be 0.763, 0.706, 0.647 and 0.649 for LA passive EF, total EF, LVEDV and M/V, respectively. The addition of LA total EF, LVEDV, M/V and the combination thereof did not significantly improve AUC values in a model containing LA passive EF. Normotensive T2DM patients were associated with LA decreased total ejection fraction, decreased passive EF and LV concentric remodeling. Among these indices, LA passive EF was the most sensitive to T2DM-related LA function changes.