Jonas Doerner

Acute Myocarditis: Multiparametric Cardiac MR Imaging

PURPOSE To evaluate the diagnostic value of cardiac magnetic resonance (MR) imaging at 3 T in patients suspected of having acute myocarditis by using a multiparametric cardiac MR imaging approach including T1 relaxation time as an additional tool for tissue characterization. MATERIALS AND METHODS Ethics commission approval was obtained for this prospective study, and written informed consent was obtained from all subjects. Twenty four patients with acute myocarditis (mean age ± standard deviation, 34.7 years ± 15.1; 75% men) and 42 control subjects (mean age, 38.7 years ± 10.2; 64% men) were included. Cardiac MR imaging approaches included relative T2 short tau inversion-recovery signal intensity ratio (T2 ratio), early gadolinium enhancement ratio, late gadolinium enhancement, native T1 relaxation times, and extracellular volume fraction. Receiver operating characteristic analysis was performed to compare diagnostic performance. The reference standard was the clinical evidence for acute myocarditis. RESULTS Native T1 relaxation times were significantly longer in patients with acute myocarditis than in control subjects (1185.3 msec ± 49.3 vs 1089.1 msec ± 44.9, respectively; P < .001). Areas under the curve of native T1 relaxation times (0.94) were higher compared with those of other cardiac MR parameters (late gadolinium enhancement, 0.90; T2 ratio, 0.79; extracellular volume fraction, 0.71; early gadolinium enhancement ratio, 0.63; P = .390, .018, .002, and < .001, respectively). Sensitivity (92%), specificity (91%), and diagnostic accuracy (91%) for native T1 relaxation times (cutoff, 1140 msec) were equivalent compared with those of the established combined Lake Louise criteria (sensitivity, 92%; specificity, 80%; diagnostic accuracy, 85%). CONCLUSION Diagnostic performance with native T1 mapping was superior to that with T2 ratio and early gadolinium enhancement ratio, and specificity was higher with native T1 mapping than that with Lake Louise criteria. This study underlines the potential of native T1 relaxation times to complement current cardiac MR approaches in patients suspected of having acute myocarditis.

Incremental value of quantitative CMR including parametric mapping for the diagnosis of acute myocarditis

AIM Cardiac magnetic resonance (CMR) can visualize inflammatory tissue changes in acute myocarditis. Several quantitative image-derived parameters have been described to enhance the diagnostic value of CMR, but no direct comparison of these techniques is available. METHODS AND RESULTS A total of 34 patients with suspected acute myocarditis and 50 control subjects underwent CMR. CMR protocol included quantitative assessment of T1 relaxation times using modified Look-Locker inversion recovery (MOLLI) and shortened MOLLI (ShMOLLI) acquisition schemes, extracellular volume fraction (ECV), T2 relaxation times, and longitudinal strain. Established Lake-Louise criteria (LLC) consisting of T2-weighted signal intensity ratio (T2-ratio), early gadolinium enhancement ratio (EGEr), and late gadolinium enhancement (LGE) were assessed. Receiver operating characteristics analysis was performed to compare diagnostic performance. Areas under the curve of native T1 (MOLLI: 0.95; ShMOLLI: 0.92) and T2 relaxation times (0.92) were higher compared with those of the other CMR parameters (T2-ratio: 0.71, EGEr: 0.71, LGE: 0.87, LLC: 0.90, ECV MOLLI: 0.77, ECV ShMOLLI: 0.80, longitudinal strain: 0.83). Combined with LGE, each native mapping technique outperformed the diagnostic performance of LLC (P < 0.01, respectively). A combination of native parameters (T1, T2, and longitudinal strain) significantly increased the diagnostic performance of CMR compared with LLC without need of contrast media application (0.99 vs. 0.90; P = 0.008). CONCLUSION In patients suspected of having acute myocarditis, diagnostic performance of CMR can be improved by implementation of quantitative CMR parameters. Especially, native mapping techniques have the potential to replace current LLC. CLINICALTRIALS. GOV NUMBER NCT02299856.

Comprehensive Cardiac Magnetic Resonance for Short‐Term Follow‐Up in Acute Myocarditis

Background Cardiac magnetic resonance (CMR) can detect inflammatory myocardial alterations in patients suspected of having acute myocarditis. There is limited information regarding the degree of normalization of CMR parameters during the course of the disease and the time window during which quantitative CMR should be most reasonably implemented for diagnostic work‐up. Methods and Results Twenty‐four patients with suspected acute myocarditis and 45 control subjects underwent CMR. Initial CMR was performed 2.6±1.9 days after admission. Myocarditis patients underwent CMR follow‐up after 2.4±0.6, 5.5±1.3, and 16.2±9.9 weeks. The CMR protocol included assessment of standard Lake Louise criteria, T1 relaxation times, extracellular volume fraction, and T2 relaxation times. Group differences between myocarditis patients and control subjects were highest in the acute stage of the disease (P<0.001 for all parameters). There was a significant and consistent decrease in all inflammatory CMR parameters over the course of the disease (P<0.01 for all parameters). Myocardial T1 and T2 relaxation times—indicative of myocardial edema—were the only single parameters showing significant differences between myocarditis patients and control subjects on 5.5±1.3‐week follow‐up (T1: 986.5±44.4 ms versus 965.1±28.1 ms, P=0.022; T2: 55.5±3.2 ms versus 52.6±2.6 ms; P=0.001). Conclusions In patients with acute myocarditis, CMR markers of myocardial inflammation demonstrated a rapid and continuous decrease over several follow‐up examinations. CMR diagnosis of myocarditis should therefore be attempted at an early stage of the disease. Myocardial T1 and T2 relaxation times were the only parameters of active inflammation/edema that could discriminate between myocarditis patients and control subjects even at a convalescent stage of the disease.

Cardiac Magnetic Resonance Reveals Signs of Subclinical Myocardial Inflammation in Asymptomatic HIV-Infected Patients.

Background—People living with chronic HIV infection are at an increased risk for cardiovascular disease. With this study, we aimed to determine the extent of cardiovascular involvement in asymptomatic HIV-infected patients by a comprehensive cardiac magnetic resonance (CMR) approach. Methods and Results—Asymptomatic patients with chronic HIV infection undergoing combination antiretroviral therapy (n=28) and control subjects (n=22) underwent CMR. HIV-infected patients were successfully controlled for the disease with a consistent plasma viremia of <200 copies/mL (mean CD4+-cell count, 475.1±307.9 cells/&mgr;L). CMR protocol allowed for the determination of cardiac function, myocardial inflammation, myocardial fibrosis, aortic stiffness, and pericardial fat volume. When compared with healthy controls, HIV-infected patients showed alterations in left ventricular function as demonstrated by a lower ejection fraction (60.9±7.1% versus 65.2±5.5%; P=0.023) and lower global peak systolic longitudinal and circumferential strain values (longitudinal strain, −17.7±3.4% versus −20.2±3.2%, circumferential strain, −21.2±4.6% versus −24.7±5.1%; P<0.001, respectively). CMR parameters indicating myocardial inflammation were elevated in HIV-infected patients (native T1 relaxation times, 1128.3±53.4 ms versus 1086.5±54.5 ms; P=0.009; relative T2 signal intensity ratio, 1.6±0.3 versus 1.4±0.3; P=0.046; early gadolinium enhancement ratio, 3.1±1.2 versus 2.1±0.6; P=0.003). Myocardial fibrosis, predominantly at the subepicardium of the midventricular and basal inferolateral wall, was prevalent in 82.1% of HIV-infected patients, but only in 27.3% of healthy controls (P<0.001). Conclusions—Comprehensive CMR revealed a high burden of cardiovascular disease in asymptomatic HIV-infected patients. Subclinical myocardial inflammation as detected by CMR may be a potential precursor of the increased cardiovascular morbidity and mortality observed in patients with chronic HIV infection.

Comparison of magnetic resonance feature tracking with harmonic phase imaging analysis (CSPAMM) for assessment of global and regional diastolic function.

AIMS Complex post-processing is required for strain-derived assessment of diastolic dysfunction (DD) using CMR-tagging (TAG). Feature-tracking (FT), allows for rapid systolic strain assessment using conventional steady-state free precession (SSFP)-Cine sequences. Aim of this study was to investigate whether FT may be employed for the clinically applicable quantification of DD. METHODS AND RESULTS 40 individuals (20 patients with DD I-III°, 20 controls) were investigated. CSPAMM and SSFP-Cine sequences were acquired in identical short-axis locations. Global and regional early diastolic strain rate (EDSR), peak diastolic strain rate (PDSR), twist, untwist and torsion were calculated from tagged and SSFP-Cine datasets. DD indices were compared, intra- as well inter-observer variability assessed. RESULTS for global EDSR correlated strongly (r=0.94), revealed good agreement and no significant differences between both methods. Correlation for regional EDSR was lower, results differed significantly in the anterior wall (p<0.05). Correlation for PDSR was moderate (r=0.63), results in the healthy control group differed significantly (p<0.05). FT derived rotational indices correlated poorly with TAG (twist: r=0.28; untwist: r=0.02; torsion: r=0.26), subgroup analysis revealed significant differences (p<0.05). Intra- and inter-observer variability for FT derived global EDSR and PDSR were comparable to TAG, but significantly higher for regional EDSR and rotational indices. CONCLUSION FT derived global EDSR allows for rapid clinical determination of diastolic dysfunction, revealing good agreement with TAG and low intra- as well as interobserver variability. However, TAG analysis not only yields higher accuracy and reproducibility of global- and regional diastolic strain, but also delivers reliable information about diastolic rotational and untwisting dynamics.

The Achilles tendon is mechanosensitive in older adults: adaptations following 14 weeks versus 1.5 years of cyclic strain exercise.

ABSTRACT The aging musculoskeletal system experiences a general decline in structure and function, characterized by a reduced adaptability to environmental stress. We investigated whether the older human Achilles tendon (AT) demonstrates mechanosensitivity (via biomechanical and morphological adaptations) in response to long-term mechanical loading. Thirty-four female adults (60–75 years) were allocated to either a medium-term (14 weeks; N=21) high AT strain cyclic loading exercise intervention or a control group (N=13), with 12 participants continuing with the intervention for 1.5 years. AT biomechanical properties were assessed using ultrasonography and dynamometry. Tendon cross-sectional area (CSA) was investigated by means of magnetic resonance imaging. A 22% exercise-related increment in ankle plantarflexion joint moment, along with increased AT stiffness (598.2±141.2 versus 488.4±136.9 N mm−1 at baseline), Youngs modulus (1.63±0.46 versus 1.37±0.39 GPa at baseline) and about 6% hypertrophy along the entire free AT were identified after 14 weeks of strength training, with no further improvement after 1.5 years of intervention. The aging AT appears to be capable of increasing its stiffness in response to 14 weeks of mechanical loading exercise by changing both its material and dimensional properties. Continuing exercise seems to maintain, but not cause further adaptive changes in tendons, suggesting that the adaptive time–response relationship of aging tendons subjected to mechanical loading is nonlinear. Highlighted Article: The stiffness of the aging Achilles tendon increases after 14 weeks of mechanical loading exercise by changing its material and dimensional properties, whereas continuing exercise causes no further adaptive changes.

Image quality evaluation of dual-layer spectral detector CT of the chest and comparison with conventional CT imaging

OBJECTIVES To evaluate image quality parameters of virtual mono-energetic (MonoE) and conventional (CR) imaging derived from a dual-layer spectral detector CT (DLCT) in oncological follow-up venous phase imaging of the chest and comparison with conventional multi-detector CT (CRMDCT) imaging. MATERIALS AND METHODS A total of 55 patients who had oncologic staging with conventional CT and DLCT of the chest in venous phase were included in this study. Established image quality parameters were derived from all datasets in defined thoracic landmarks. Attenuation, image noise, and signal-/contrast- to noise ratios (SNR, CNR) were compared between CRDLCT and MonoE as well as CRMDCT imaging. Two readers performed subjective image analysis. RESULTS CRMDCT showed significant lower attenuation values compared to CRDLCT and MonoE at 40-70keV (p≤0.05). Moreover, MonoE at 40-70keV revealed significantly higher attenuations values compared to CRDLCT (p<0.001). Noise was statistically lower in CRMDCT compared with CRDLCT and MonoE at 40keV (11.4±2.3 HU vs. 12.0±3.1 HU vs. 11.7±5.2 HU; p<0.001). In contrast, all MonoE levels showed significantly lower noise levels compared to CRDLCT (p<0.001). SNR was not significantly different between CRMDCT and CRDLCT (13.5±3.7 vs. 14.4±5.3; p>0.99). SNR values were significantly increased for MonoE at 40-80keV compared to CRMDCT and CRDLCT (p<0.001). CRDLCT and MonoE (40-70keV) from DLCT revealed significantly higher CNR values than CRMDCT (p<0.001). In subjective analysis, MonoE at 40keV surpassed all other image reconstructions except for noise in MonoE at 70 keV. CONCLUSION In dual-layer spectral detector CT, MonoE at low keV showed superior image quality compared to conventional images derived from the same system and may therefore be added to clinical routine imaging protocols. Whether MonoE reconstructions yield additional diagnostic information is still unknown.

Feature-tracking myocardial strain analysis in acute myocarditis: diagnostic value and association with myocardial oedema

ObjectivesTo investigate the diagnostic value of cardiac magnetic resonance (CMR) feature-tracking (FT) myocardial strain analysis in patients with suspected acute myocarditis and its association with myocardial oedema.MethodsForty-eight patients with suspected acute myocarditis and 35 control subjects underwent CMR. FT CMR analysis of systolic longitudinal (LS), circumferential (CS) and radial strain (RS) was performed. Additionally, the protocol allowed for the assessment of T1 and T2 relaxation times.ResultsWhen compared with healthy controls, myocarditis patients demonstrated reduced LS, CS and RS values (LS: -19.5 ± 4.4% vs. -23.6 ± 3.1%, CS: -23.0 ± 5.8% vs. -27.4 ± 3.4%, RS: 28.9 ± 8.5% vs. 32.4 ± 7.4%; P < 0.05, respectively). LS (T1: r = 0.462, P < 0.001; T2: r = 0.436, P < 0.001) and CS (T1: r = 0.429, P < 0.001; T2: r = 0.467, P < 0.001) showed the strongest correlations with T1 and T2 relaxations times. Area under the curve of LS (0.79) was higher compared with those of CS (0.75; P = 0.478) and RS (0.62; P = 0.008).ConclusionsFT CMR myocardial strain analysis might serve as a new tool for assessment of myocardial dysfunction in the diagnostic work-up of patients suspected of having acute myocarditis. Especially, LS and CS show a sufficient diagnostic performance and were most closely correlated with CMR parameters of myocardial oedema.Key Points• Myocardial strain measures are considerably reduced in patients with suspected myocarditis.• Myocardial strain measures can sufficiently discriminate between diseased and healthy patients.• Myocardial strain measures show basic associations with the extent of myocardial oedema/inflammation.

Thoracic-abdominal imaging with a novel dual-layer spectral detector CT: intra-individual comparison of image quality and radiation dose with 128-row single-energy acquisition

Background A novel, multi-energy, dual-layer spectral detector computed tomography (SDCT) is commercially available now with the vendor’s claim that it yields the same or better quality of polychromatic, conventional CT images like modern single-energy CT scanners without any radiation dose penalty. Purpose To intra-individually compare the quality of conventional polychromatic CT images acquired with a dual-layer spectral detector (SDCT) and the latest generation 128-row single-energy-detector (CT128) from the same manufacturer. Material and Methods Fifty patients underwent portal-venous phase, thoracic-abdominal CT scans with the SDCT and prior CT128 imaging. The SDCT scanning protocol was adapted to yield a similar estimated dose length product (DLP) as the CT128. Patient dose optimization by automatic tube current modulation and CT image reconstruction with a state-of-the-art iterative algorithm were identical on both scanners. CT image contrast-to-noise ratio (CNR) was compared between the SDCT and CT128 in different anatomic structures. Image quality and noise were assessed independently by two readers with 5-point-Likert-scales. Volume CT dose index (CTDIvol), and DLP were recorded and normalized to 68 cm acquisition length (DLP68). Results The SDCT yielded higher mean CNR values of 30.0% ± 2.0% (26.4–32.5%) in all anatomic structures (P < 0.001) and excellent scores for qualitative parameters surpassing the CT128 (all P < 0.0001) with substantial inter-rater agreement (κ ≥ 0.801). Despite adapted scan protocols the SDCT yielded lower values for CTDIvol (–10.1 ± 12.8%), DLP (−13.1 ± 13.9%), and DLP68 (–15.3 ± 16.9%) than the CT128 (all P < 0.0001). Conclusion The SDCT scanner yielded better CT image quality compared to the CT128 and lower radiation dose parameters.

Utilization of virtual mono-energetic images (MonoE) derived from a dual-layer spectral detector CT (SDCT) for the assessment of abdominal arteries in venous contrast phase scans

OBJECTIVES To investigate the utilization of virtual mono-energetic images (MonoE) at low kiloelectron volt (keV) levels derived from a dual-layer spectral detector CT (SDCT) for the assessment of abdominal arteries in venous contrast phase scans using arterial phase imaging as an internal reference standard. MATERIALS AND METHODS A total of 50 patients who received arterial and venous phase imaging of the abdomen on a SDCT system were included in this study. Absolute attenuation, noise, signal- and contrast to noise ratios (SNR; CNR) as well as arterial diameters in defined landmarks were assessed. In arterial phase, conventional reconstructions (CRART) as well as MonoEART at 40keV and in venous phase, conventional reconstructions (CRVEN) as well as MonoEVEN at 70 and 40keV were investigated and intra-individual comparisons were performed. If an artery stenosis (10 patients) was present, the degree of stenosis was assessed according to the system of the North American Symptomatic Carotid Endarterectomy Trial (NASCET). RESULTS MonoE 40keV yielded significantly higher attenuation values (in arterial as well as in venous phase) compared to CRART (p<0.001) while noise levels were substantially low. This resulted in markedly superior SNR and CNR in large vessel compared to CRART. Luminal diameters were significantly smaller in MonoE 40keV in both contrast phases compared to CRART (p<0.001), whereas no significant differences were found between both MonoE reconstructions (p≥0.92). The degree of vessel stenosis was significantly higher in MonoE 40keV of both contrast phases compared to CRART (p≥0.02). CONCLUSION MonoE at low keV of venous contrast phase scans derived from a novel SDCT are suitable for the assessment of arteries in the abdomen and subsequent stenosis assessment. However, MonoE at 40keV constantly showed significant smaller luminal diameters than the corresponding conventional reconstructions (including the reference standard). This is possibly due to an improved differentiation of the vessel lumen from the wall and raises the question, which imaging technique should be used as an appropriate reference standard for vascular SDCT imaging studies.