In Vivo Fluorine Imaging Using 1.5 Tesla MRI for Depiction of Experimental Myocarditis in a Rodent Animal Model.

The usefulness of perfluorocarbon nanoemulsions for the imaging of experimental myocarditis has been demonstrated in a high-field 9.4 Tesla MRI scanner. Our proof-of-concept study investigated the imaging capacity of PFC-based 19F/1H MRI in an animal myocarditis model using a clinical field strength of 1.5 Tesla. To induce experimental myocarditis, five male rats (weight ~300 g, age ~50 days) were treated with one application per week of doxorubicin (2 mg/kg BW) over a period of six weeks. Three control animals received the identical volume of sodium chloride 0.9% instead. Following week six, all animals received a single 4 ml injection of an 20% oil-in-water perfluorooctylbromide nanoemulsion 24 hours prior to in vivo1H/19F imaging on a 1.5 Tesla MRI. After euthanasia, cardiac histology and immunohistochemistry using CD68/ED1 macrophage antibodies were performed, measuring the inflamed myocardium in µm2 for further statistical analysis to compare the extent of the inflammation with the 19F-MRI signal intensity. All animals treated with doxorubicin showed a specific signal in the myocardium, while no myocardial signal could be detected in the control group. Additionally, the doxorubicin group showed a significantly higher SNR for 19F and a stronger CD68/ED1 immunhistoreactivity compared to the control group. This proof-of-concept study demonstrates that perfluorocarbon nanoemulsions could be detected in an in vivo experimental myocarditis model at a currently clinically relevant field strength.

Long-term prognostic value of vasodilator stress cardiac magnetic resonance in patients with atrial fibrillation.

AIMS: Although the prevalence of coronary artery disease (CAD) is high among patients with atrial fibrillation (AF), studies on stress perfusion cardiac magnetic resonance (CMR) imaging frequently exclude patients with AF, and its prognostic and diagnostic value in high-risk patients with suspected or known CAD remains unclear. METHODS AND RESULTS: In this longitudinal cohort study, we included 164 consecutive patients with AF during vasodilator perfusion CMR. Diagnostic value was evaluated regarding invasive coronary angiography in a subset of patients. We targeted a follow-up of >5 years and used CMR results as stratification, and the primary outcome was major adverse cardiac events [MACE, cardiovascular (CV) death and myocardial infarction (MI)]. Secondary outcomes included late coronary revascularization or stroke and the components of the primary outcome. Of the whole cohort (73.8% male, mean age 72.2 years ± 7.8 SD), 99.4% were successfully scanned (163/164 patients). Median CHA2DS2-VASc score was 4 [interquartile range (IQR) 3-5], and median 10-year risk for CV events based on SMART risk score was high (24%, IQR 16-32%). Thirty-two patients (19.6%) presented with ischaemia and 52 patients (31.9%) with late gadolinium enhancement (LGE). A combination of LGE and inducible ischaemia was present in 20 patients (12.3%). Diagnostic accuracy was 86.2% [confidence interval (CI) 68.3-96.1%]. The median follow-up was 6.6 years (IQR 3.6-7.8). Ischaemia in vasodilator perfusion CMR was significantly associated with the occurrence of MACE [P < 0.01; hazard ratio (HR) 2.65, CI 1.39-5.08], as well as LGE (P = 0.03; 1.74, CI 1.07-3.64) and the combination of both (P < 0.01; HR 2.67, CI 1.59-5.62). After adjustment by age, left ventricular ejection fraction, and the presence of diabetes, ischaemia in vasodilator perfusion CMR remained significantly associated with the occurrence of MACE (2.10, CI 1.08-4.10; P = 0.03). In secondary endpoint analysis, there was a significant association of ischaemia in CMR with CV death (P < 0.05; HR 1.93, CI 0.95-3.9) and MI (P < 0.01; HR 13, CI 1.35-125.4), while no significant association was found regarding the occurrence of revascularization (P = 0.45; HR 1.43, CI 0.57-3.58) or stroke (P = 0.99; HR 0.99, CI 0.21-2.59). CONCLUSIONS: Vasodilator stress perfusion CMR demonstrated an excellent diagnostic and significant prognostic value at long-term follow-up in high-risk patients with persistent AF and suspected or known CAD.

Non-invasive CMR-Based Quantification of Myocardial Power and Efficiency Under Stress and Ischemic Conditions in Landrace Pigs.

Background: Myocardial efficiency should be maintained stable under light-to-moderate stress conditions, but ischemia puts the myocardium at risk for impaired functionality. Additionally, the measurement of such efficiency typically requires invasive heart catheterization and exposure to ionizing radiation. In this work, we aimed to non-invasively assess myocardial power and the resulting efficiency during pharmacological stress testing and ischemia induction. Methods: In a cohort of n = 10 healthy Landrace pigs, dobutamine stress testing was performed, followed by verapamil-induced ischemia alongside cardiac magnetic resonance (CMR) imaging. External myocardial power, internal myocardial power, and myocardial efficiency were assessed non-invasively using geometrical and functional parameters from CMR volumetric as well as blood flow and pressure measurements. Results: External myocardial power significantly increased under dobutamine stress [2.3 (1.6-3.1) W/m2 vs. 1.3 (1.1-1.6) W/m2, p = 0.005] and significantly decreased under verapamil-induced ischemia [0.8 (0.5-0.9) W/m2, p = 0.005]. Internal myocardial power [baseline: 5.9 (4.6-8.5) W/m2] was not affected by dobutamine [7.5 (6.9-9.0) W/m2, p = 0.241] nor verapamil [5.8 (4.7-8.8) W/m2, p = 0.878]. Myocardial efficiency did not change from baseline to dobutamine [21% (15-27) vs. 31% (20-44), p = 0.059] but decreased significantly during verapamil-induced ischemia [10% (8-13), p = 0.005]. Conclusion: In healthy Landrace pigs, dobutamine stress increased external myocardial power, whereas myocardial efficiency was maintained stable. On the contrary, verapamil-induced ischemia substantially decreased external myocardial power and myocardial efficiency. Non-invasive CMR was able to quantify these efficiency losses and might be useful for future clinical studies evaluating the effects of therapeutic interventions on myocardial energetics.

Cardiac magnetic resonance T2 mapping and feature tracking in athlete's heart and HCM.

OBJECTIVES: Distinguishing hypertrophic cardiomyopathy (HCM) from left ventricular hypertrophy (LVH) due to systematic training (athlete's heart, AH) from morphologic assessment remains challenging. The purpose of this study was to examine the role of T2 mapping and deformation imaging obtained by cardiovascular magnetic resonance (CMR) to discriminate AH from HCM with (HOCM) or without outflow tract obstruction (HNCM). METHODS: Thirty-three patients with HOCM, 9 with HNCM, 13 strength-trained athletes as well as individual age- and gender-matched controls received CMR. For T2 mapping, GRASE-derived multi-echo images were obtained and analyzed using dedicated software. Besides T2 mapping analyses, left ventricular (LV) dimensional and functional parameters were obtained including LV mass per body surface area (LVMi), interventricular septum thickness (IVS), and global longitudinal strain (GLS). RESULTS: While LVMi was not significantly different, IVS was thickened in HOCM patients compared to athlete's. Absolute values of GLS were significantly increased in patients with HOCM/HNCM compared to AH. Median T2 values were elevated compared to controls except in athlete's heart. ROC analysis revealed T2 values (AUC 0.78) and GLS (AUC 0.91) as good parameters to discriminate AH from overall HNCM/HOCM. CONCLUSION: Discrimination of pathologic from non-pathologic LVH has implications for risk assessment of competitive sports in athletes. Multiparametric CMR with parametric T2 mapping and deformation imaging may add information to distinguish AH from LVH due to HCM. KEY POINTS: • Structural analyses using T2 mapping cardiovascular magnetic resonance imaging (CMR) may help to further distinguish myocardial diseases. • To differentiate pathologic from non-pathologic left ventricular hypertrophy, CMR including T2 mapping was obtained in patients with hypertrophic obstructive/non-obstructive cardiomyopathy (HOCM/HNCM) as well as in strength-trained athletes. • Elevated median T2 values in HOCM/HNCM compared with athlete's may add information to distinguish athlete's heart from pathologic left ventricular hypertrophy.

Cardiac Myxomas Show Elevated Native T1, T2 Relaxation Time and ECV on Parametric CMR.

Introduction: While cardiac tumors are rare, their identification and differentiation has wide clinical implications. Recent cardiac magnetic resonance (CMR) parametric mapping techniques allow for quantitative tissue characterization. Our aim was to examine the range of values encountered in cardiac myxomas in correlation to histological measurements. Methods and Results: Nine patients with histologically proven cardiac myxomas were included. CMR (1.5 Tesla, Philips) including parametric mapping was performed in all patients pre-operatively. All data are reported as mean ± standard deviation. Compared to myocardium, cardiac myxomas demonstrated higher native T1 relaxation times (1,554 ± 192 ms vs. 1,017 ± 58 ms, p < 0.001), ECV (46.9 ± 13.0% vs. 27.1 ± 2.6%, p = 0.001), and T2 relaxation times (209 ± 120 ms vs. 52 ± 3 ms, p = 0.008). Areas with LGE showed higher ECV than areas without (54.3 ± 17.8% vs. 32.7 ± 18.6%, p = 0.042), with differences in native T1 relaxation times (1,644 ± 217 ms vs. 1,482 ± 351 ms, p = 0.291) and T2 relaxation times (356 ± 236 ms vs. 129 ± 68 ms, p = 0.155) not reaching statistical significance. Conclusions: Parametric CMR showed elevated native T1 and T2 relaxation times and ECV values in cardiac myxomas compared to normal myocardium, reflecting an increased interstitial space and fluid content. This might help in the differentiation of cardiac myxomas from other tumor entities.

Feasibility and Robustness of 3T Magnetic Resonance Angiography Using Modified Dixon Fat Suppression in Patients With Known or Suspected Peripheral Artery Disease.

Objective: Contrast-enhanced magnetic resonance angiography (CE-MRA) is a well-established non-invasive imaging technique for the assessment of peripheral artery disease (PAD). A subtractionless method using modified Dixon (mDixon) fat suppression showed superior image quality at 1.5T over the common subtraction method, using a three-positions stepping table approach with a single dose of contrast agent. The aim of this study was to investigate the feasibility of subtractionless first-pass peripheral MRA at 3T in patients with known or suspected PAD and to compare the performance in terms of vessel-to-background contrast (VBC), signal-to-noise ratio (SNR), and subjective image quality to conventional subtraction MRA. Methods: Ten patients [mean age 69 years ± 12 standard deviation (SD)] with known or suspected PAD were examined on a clinical 3T scanner (Ingenia, Philips Healthcare, Best, Netherlands) at three table positions using subtractionless and subtraction first-pass peripheral MRA. Two readers rated image quality on a four- point scale. Interobserver agreement was expressed in quadratic weighted κ values. VBC was assessed with a semi-automated process and SNR was compared in a healthy volunteer. Results: Subjective image quality was significantly better with the subtractionless method overall (mean image quality for mDixon imaging: 2.88 ± 0.32 SD vs. for subtraction imaging: 2.57 ± 0.48 SD; P < 0.001) and per table position (abdominal position: 2.88 ± 0.32 vs. 2.57 ± 0.48 SD; P < 0.001); upper leg position: (2.97 ± 0.15 SD vs. 2.68 ± 0.37 SD; P < 0.001; lower leg position: 2.60 ± 0.50 SD vs. 2.13 ± 0.60 SD; P < 0.001). Vessel-to-background contrast increased by 22% with the subtractionless method overall (mean VBC for mDixon imaging: 23.16 ± 8.4 SD vs. for subtraction imaging: 19.00 ± 8.1 SD; factor 1.22, P < 0.001). SNR was 82% higher with the subtractionless method (overall SNR gain 1.82; P < 0.001). Conclusion: This study demonstrated the feasibility and robustness of subtractionless first-pass peripheral MRA at 3T in patients with known or suspected PAD using a three- positions stepping table approach with a single dose of contrast agent. It showed increased image quality compared to the conventional subtraction method and superior performance in terms of SNR and vessel-to-background contrast.

Strain-encoded cardiac magnetic resonance imaging: a new approach for fast estimation of left ventricular function.

BACKGROUND: Recently introduced fast strain-encoded (SENC) cardiac magnetic resonance (CMR) imaging (fast-SENC) provides real-time acquisition of myocardial performance in a single heartbeat. We aimed to test the ability and accuracy of real-time strain-encoded CMR imaging to estimate left ventricular volumes, ejection fraction and mass. METHODS: Thirty-five subjects (12 healthy volunteers and 23 patients with known or suspected coronary artery disease) were investigated. All study participants were imaged at 1.5 Tesla MRI scanner (Achieva, Philips) using an advanced CMR study protocol which included conventional cine and fast-SENC imaging. A newly developed real-time free-breathing SENC imaging technique based on the acquisition of two images with different frequency modulation was employed. RESULTS: All parameters were successfully derived from fast-SENC images with total study time of 105 s (a 15 s scan time and a 90 s post-processing time). There was no significant difference between fast-SENC and cine imaging in the estimation of LV volumes and EF, whereas fast-SENC underestimated LV end-diastolic mass by 7%. CONCLUSION: The single heartbeat fast-SENC technique can be used as a good alternative to cine imaging for the precise calculation of LV volumes and ejection fraction while the technique significantly underestimates LV end-diastolic mass.

Reproducibility study on myocardial strain assessment using fast-SENC cardiac magnetic resonance imaging.

Myocardial strain is a well validated parameter for estimating left ventricular (LV) performance. The aim of our study was to evaluate the inter-study as well as intra- and interobserver reproducibility of fast-SENC derived myocardial strain. Eighteen subjects (11 healthy individuals and 7 patients with heart failure) underwent a cardiac MRI examination including fast-SENC acquisition for evaluating left ventricular global longitudinal (GLS) and circumferential strain (GCS) as well as left ventricular ejection fraction (LVEF). The examination was repeated after 63 [range 49‒87] days and analyzed by two experienced observers. Ten datasets were repeatedly assessed after 1 month by the same observer to test intraobserver variability. The reproducibility was measured using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. Patients with heart failure demonstrated reduced GLS and GCS compared to healthy controls (-15.7 ± 3.7 vs. -20.1 ± 1.4; p = 0.002 for GLS and -15.3 ± 3.7 vs. -21.4 ± 1.1; p = 0.001 for GCS). The test-retest analysis showed excellent ICC for LVEF (0.92), GLS (0.94) and GCS (0.95). GLS exhibited excellent ICC (0.99) in both intra- and interobserver variability analysis with very narrow limits of agreement (-0.6 to 0.5 for intraobserver and -1.3 to 0.96 for interobserver agreement). Similarly, GCS showed excellent ICC (0.99) in both variability analyses with narrow limits of agreement (-1.1 to 1.2 for intraobserver and -1.7 to 1.3 for interobserver agreement), whereas LVEF showed larger limits of agreement (-14.4 to 10.1). The analysis of fast-SENC derived myocardial strain using cardiac MRI provides a highly reproducible method for assessing LV functional performance.

CMR stress testing in a patient with morbid obesity (BMI 58 kg/m2) and suspected coronary artery disease.

BACKGROUND: Severe obesity is asscociated with an increased risk of coronary artery disease (CAD) but non-invasive cardiac imaging modalities have important technical limits. CASE PRESENTATION: We report a case of a 58-year old patient with suspected CAD and severely elevated BMI of 58 kg/m2. CONCLUSIONS: Stress-CMR was able to non-invasively stratify risk with good imaging quality despite the body dimensions of the patient.

Feasibility study of MR-guided transgluteal targeted in-bore biopsy for suspicious lesions of the prostate at 3 Tesla using a freehand approach.

OBJECTIVE: The aim of our study was (1) to establish an in-bore targeted biopsy of suspicious prostate lesions, avoiding bowel penetration using a transgluteal approach and (2) to assess operator setup, patient comfort and safety aspects in the clinical setting for freehand real-time MR-guidance established for percutaneous procedures in an open MR-scanner. MATERIAL AND METHODS: 30 patients with suspect prostate lesions were biopsied in a cylindrical 3T-MRI system using a transgluteal approach in freehand technique. One to three biopsies were sampled using continuous dynamic imaging. Size, location and visibility of the lesion, intervention time, needle artefact size, interventional complications and histopathological diagnosis were recorded. RESULTS: All biopsies were technically successful. Nineteen patients showed evidence of prostate carcinoma. Cancer detection rate was 50 % in patients with previously negative TRUS-biopsy. The average intervention time was 26 min including a learning curve as the time was 13 min by the end of the study. No antibiotic prophylaxis was performed as none of the patients showed signs of infection. CONCLUSIONS: MR-guided targeted freehand biopsies of prostate lesions using a transgluteal approach are both technically feasible and time efficient in a standard closed-bore 3T-MR scanner as well as safe for the individual patient. KEY POINTS: • Open-bore freehand interventional principles were adapted to closed-bore systems. • Prostate MR-guided freehand biopsies were feasible in a clinical setting. • A transgluteal approach provides a short and simplified work flow. • An inoculation of the prostate with bowel flora is avoided. • The intervention time is comparable to the stereotactic approach.

Fatty metaplasia quantification and impact on regional myocardial function as assessed by advanced cardiac MR imaging.

OBJECTIVE: This study aimed to investigate the advantages of recently developed cardiac imaging techniques of fat-water separation and feature tracking to characterize better individuals with chronic myocardial infarction (MI). MATERIALS AND METHODS: Twenty patients who had a previous MI underwent CMR imaging. The study protocol included routine cine and late gadolinium enhancement (LGE) technique. In addition, mDixon LGE imaging was performed in every patient. Left ventricular (LV) circumferential (EccLV) and radial (ErrLV) strain were calculated using dedicated software (CMR42, Circle, Calgary, Canada). The extent of global scar was measured in LGE and fat-water separated images to compare conventional and recent CMR imaging techniques. RESULTS: The infarct size derived from conventional LGE and fat-water separated images was similar. However, detection of lipomatous metaplasia was only possible with mDixon imaging. Subjects with fat deposition demonstrated a significantly smaller percentage of fibrosis than those without fat (10.68 ± 5.07% vs. 13.83 ± 6.30%; p = 0.005). There was no significant difference in EccLV or ErrLV between myocardial segments containing fibrosis only and fibrosis with fat. However, EccLV and ErrLV values were significantly higher in myocardial segments adjacent to fibrosis with fat deposition than in those adjacent to LGE only. CONCLUSIONS: Advanced CMR imaging ensures more detailed tissue characterization in patients with chronic MI without a relevant increase in imaging and post-processing time. Fatty metaplasia may influence regional myocardial deformation especially in the myocardial segments adjacent to scar tissue. A simplified and shortened myocardial viability CMR protocol might be useful to better characterize and stratify patients with chronic MI.

Artefact-free late gadolinium enhancement imaging in patients with implanted cardiac devices using a modified broadband sequence: current strategies and results from a real-world patient cohort.

Aims: Cardiac magnetic resonance (CMR) imaging in patients with implanted cardiac devices is often limited by device-related imaging artefacts. Limitations can potentially be overcome by employing a broadband late gadolinium enhancement (LGE)-CMR imaging technique. The purpose of this study was to investigate the relationship between implanted cardiac devices and the optimal frequency offset on broadband LGE-CMR imaging to increase the artefact-free visibility of myocardial segments. Methods and results: A phantom study was performed to characterize magnetic field disturbances related to 15 different cardiac devices. This was complemented by B0 and B1+ imaging of three different device types in four healthy volunteers. Findings were validated in 28 patients with an indication for arrhythmogenic substrate characterization before catheter ablation. In the phantom study, the placement of a PM, implantable cardioverter-defibrillator (ICD) or CRT-D generator led to a significant impairment of the radiofrequency field. B0 mapping in phantom and volunteers showed the highest off-resonance maximum with CRT-D systems with the maximum off-resonance significantly decreasing for ICD or PM systems, respectively. In all patients, with conventional LGE imaging 73.1% (61.5-92.3%) of LV segments were free of device-related artefacts, while with the broadband LGE technique, a significant increase of artefact-free segments was achieved [96.4% (85.7-100%); P = 0.00008]. Conclusion: Using a modified broadband sequence for LGE imaging significantly increased the number of artefact-free myocardial segments thereby leading to improved diagnostic value of the CMR exam. Since the occurrence and extent of hyperintensity artefacts are closely related to the individual device, more studies are warranted to evaluate if the results can be extrapolated to other devices and manufacturers.

A novel multiparametric imaging approach to acute myocarditis using T2-mapping and CMR feature tracking.

BACKGROUND: The aim of this study was to evaluate the diagnostic potential of a novel cardiovascular magnetic resonance (CMR) based multiparametric imaging approach in suspected myocarditis and to compare it to traditional Lake Louise criteria (LLC). METHODS: CMR data from 67 patients with suspected acute myocarditis were retrospectively analyzed. Seventeen age- and gender-matched healthy subjects served as control. T2-mapping data were acquired using a Gradient-Spin-Echo T2-mapping sequence in short-axis orientation. T2-maps were segmented according to the 16-segments AHA-model and segmental T2 values and pixel-standard deviation (SD) were recorded. Afterwards, the parameters maxT2 (the highest segmental T2 value) and madSD (the mean absolute deviation (MAD) of the pixel-SDs) were calculated for each subject. Cine sequences in three long axes and a stack of short-axis views covering the left and right ventricle were analyzed using a dedicated feature tracking algorithm. RESULTS: A multiparametric imaging model containing madSD and LV global circumferential strain (GCSLV) resulted in the highest diagnostic performance in receiver operating curve analyses (area under the curve [AUC] 0.84) when compared to any model containing a single imaging parameter or to LLC (AUC 0.79). Adding late gadolinium enhancement (LGE) to the model resulted in a further increased diagnostic performance (AUC 0.93) and yielded the highest diagnostic sensitivity of 97% and specificity of 77%. CONCLUSIONS: A multiparametric CMR imaging model including the novel T2-mapping derived parameter madSD, the feature tracking derived strain parameter GCSLV and LGE yields superior diagnostic sensitivity in suspected acute myocarditis when compared to any imaging parameter alone and to LLC.

Acute versus Chronic Myocardial Infarction: Diagnostic Accuracy of Quantitative Native T1 and T2 Mapping versus Assessment of Edema on Standard T2-weighted Cardiovascular MR Images for Differentiation.

Purpose To analyze the diagnostic accuracy of native T1 and T2 mapping compared with visual and quantitative assessment of edema on T2-weighted cardiac magnetic resonance (MR) images to differentiate between acute and chronic myocardial infarction. Materials and Methods This study had institutional ethics committee approval. Written informed consent was obtained from 67 consecutive patients (57 years ± 12; 78% men) with a first acute myocardial infarction, who were prospectively enrolled between April 2011 and June 2015. Four serial 1.5-T MR imaging examinations were performed at 8 days ± 5, 7 weeks ± 2, 3 months ± 0.5, and 6 months ± 1.4 after infarction and included T2-weighted, native T1/T2 mapping, and late gadolinium enhancement MR imaging. Complete follow-up data were obtained in 42 patients. Regional native T1/T2 relaxation time, T2-weighted ratio, and extracellular volume were serially measured in infarcted and remote myocardium. Receiver operating characteristic (ROC) analysis was used to determine the diagnostic accuracy of the MR imaging parameters for discriminating between acute and chronic myocardial infarction. Results Native T1 of infarcted myocardium decreased from 1286 msec ± 99 at baseline to 1077 msec ± 50 at 6 months (P < .0001), whereas T2 decreased from 84 msec ± 10 to 58 msec ± 4 (P < .0001). The T2-weighted ratio decreased from 4.1 ± 1.0 to 2.4 ± 0.6 (P < .0001). Of all the MR imaging parameters obtained, native T1 and T2 yielded the best areas under the ROC curve (AUCs) of 0.975 and 0.979, respectively, for differentiating between acute and chronic myocardial infarction. Visual analysis of the presence of edema at standard T2-weighted cardiac MR imaging resulted in an inferior AUC of 0.863 (P < .01). Conclusion Native T1 and T2 of infarcted myocardium are excellent discriminators between acute and chronic myocardial infarction and are superior to all other MR imaging parameters. Online supplemental material is available for this article.

Re-evaluation of a novel approach for quantitative myocardial oedema detection by analysing tissue inhomogeneity in acute myocarditis using T2-mapping.

OBJECTIVES: To re-evaluate a recently suggested approach of quantifying myocardial oedema and increased tissue inhomogeneity in myocarditis by T2-mapping. METHODS: Cardiac magnetic resonance data of 99 patients with myocarditis were retrospectively analysed. Thirthy healthy volunteers served as controls. T2-mapping data were acquired at 1.5 T using a gradient-spin-echo T2-mapping sequence. T2-maps were segmented according to the 16-segments AHA-model. Segmental T2-values, segmental pixel-standard deviation (SD) and the derived parameters maxT2, maxSD and madSD were analysed and compared to the established Lake Louise criteria (LLC). RESULTS: A re-estimation of logistic regression models revealed that all models containing an SD-parameter were superior to any model containing global myocardial T2. Using a combined cut-off of 1.8 ms for madSD + 68 ms for maxT2 resulted in a diagnostic sensitivity of 75% and specificity of 80% and showed a similar diagnostic performance compared to LLC in receiver-operating-curve analyses. Combining madSD, maxT2 and late gadolinium enhancement (LGE) in a model resulted in a superior diagnostic performance compared to LLC (sensitivity 93%, specificity 83%). CONCLUSIONS: The results show that the novel T2-mapping-derived parameters exhibit an additional diagnostic value over LGE with the inherent potential to overcome the current limitations of T2-mapping. KEY POINTS: • A novel quantitative approach to myocardial oedema imaging in myocarditis was re-evaluated. • The T2-mapping-derived parameters maxT2 and madSD were compared to traditional Lake-Louise criteria. • Using maxT2 and madSD with dedicated cut-offs performs similarly to Lake-Louise criteria. • Adding maxT2 and madSD to LGE results in further increased diagnostic performance. • This novel approach has the potential to overcome the limitations of T2-mapping.

Abnormal T2 mapping cardiovascular magnetic resonance correlates with adverse clinical outcome in patients with suspected acute myocarditis.

BACKGROUND: While most patients recover from suspected acute myocarditis (sAMC) some develop progressive disease with 5-year mortality up to 20%. Recently, parametric Cardiovascular Magnetic Resonance (CMR) approaches, quantifying native T1 and T2 relaxation time, have demonstrated the ability to increase diagnostic accuracy. However, prognostic implications of T2 values in this cohort are unknown. The purpose of the study was to investigate the prognostic relevance of elevated CMR T2 values in patients with sAMC. METHODS AND RESULTS: We carried out a prospective study in 46 patients with sAMC defined by current ESC recommendations. A combined endpoint was defined by the occurrence of at least one major adverse cardiac event (MACE) and hospitalisation for heart failure. Event rate was 24% (n = 11) for 1-year-MACE and hospitalisation. A follow-up after 11 ± 7 months was performed in 98% of the patients. Global T2 values were significantly increased at acute stage of disease compared to controls and decreased over time. During acute disease, elevated global T2 time (odds ratio 6.3, p < 0.02) as well as myocardial fraction with T2 time >80 ms (odds ratio 4.9, p < 0.04) predicted occurrence of the combined endpoint. Patients with clinical recovery revealed significantly decreased T2 relaxation times at follow-up examinations; however, T2 values were still elevated compared to healthy controls. CONCLUSION: Assessment of myocardial T2 relaxation times at initial presentation facilitates CMR-based risk stratification in patients with acute myocarditis. T2 Mapping may emerge as a new tool to monitor inflammatory myocardial injuries during the course of disease.

T1 and T2 mapping cardiovascular magnetic resonance imaging techniques reveal unapparent myocardial injury in patients with myocarditis.

INTRODUCTION: This study evaluated the ability of T1 and T2 mapping cardiovascular magnetic resonance (CMR) to detect myocardial injury in apparently normal myocardium of patients with myocarditis. MATERIALS AND METHODS: We included 20 patients with "infarct-like" acute myocarditis who had typical focal myocardial lesions on late gadolinium enhancement (LGE) images as well as 20 healthy controls. The CMR protocol consisted of a standard myocarditis protocol which was combined with T1 (modified Look-Locker inversion recovery (MOLLI) with a 3(3)5 scheme and T2 mapping (hybrid gradient- and spin-echo multi-echo sequence, GraSE). First, LGE images were used to depict focal myocardial injury and apparently normal, remote myocardium. Second, native T1, T2 and ECV values were obtained in focal lesions but also in apparently normal myocardium. Third, native T1, T2 and ECV values ≥2 standard deviations above reference values obtained in healthy volunteers were used to quantify myocardial injury in patients with myocarditis. RESULTS: Apparently normal myocardium had significantly higher median native T1 [1095 (1055-1148) ms] and ECV [34 (32-35) %] values compared to reference values from healthy volunteers, which were 1051 (1021-1064) ms (p < 0.01) and 26 (24-27) % (p < 0.0001). Furthermore, a nonsignificant increase in median myocardial T2 was detected in apparently normal myocardium of patients with myocarditis compared to healthy volunteers [59 (55-65) vs. 56 (54-60) ms; p = 0.18]. Consequently, the amount of myocardial injury was significantly larger on native T1 [48 (32-56) %; p < 0.01] and ECV maps [58 (50-66) %; p < 0.01] compared to LGE [14 (9-20) %]. CONCLUSIONS: Native T1 and ECV maps reveal hidden myocardial injury in normal appearing myocardium of patients with myocarditis. The amount of myocardial injury in myocarditis was underestimated by conventional LGE imaging.

Magnetic resonance imaging guided transatrial electrophysiological studies in swine using active catheter tracking - experience with 14 cases.

OBJECTIVES: To evaluate the feasibility of performing comprehensive Cardiac Magnetic resonance (CMR) guided electrophysiological (EP) interventions in a porcine model encompassing left atrial access. METHODS: After introduction of two femoral sheaths 14 swine (41 ± 3.6 kg) were transferred to a 1.5 T MR scanner. A three-dimensional whole-heart sequence was acquired followed by segmentation and the visualization of all heart chambers using an image-guidance platform. Two MR conditional catheters were inserted. The interventional protocol consisted of intubation of the coronary sinus, activation mapping, transseptal left atrial access (n = 4), generation of ablation lesions and eventually ablation of the atrioventricular (AV) node. For visualization of the catheter tip active tracking was used. Catheter positions were confirmed by passive real-time imaging. RESULTS: Total procedure time was 169 ± 51 minutes. The protocol could be completed in 12 swine. Two swine died from AV-ablation induced ventricular fibrillation. Catheters could be visualized and navigated under active tracking almost exclusively. The position of the catheter tips as visualized by active tracking could reliably be confirmed with passive catheter imaging. CONCLUSIONS: Comprehensive CMR-guided EP interventions including left atrial access are feasible in swine using active catheter tracking. KEY POINTS: • Comprehensive CMR-guided electrophysiological interventions including LA access were conducted in swine. • Active catheter-tracking allows efficient catheter navigation also in a transseptal approach. • More MR-conditional tools are needed to facilitate left atrial interventions in humans.

Cardiac Magnetic Resonance Imaging Using an Open 1.0T MR Platform: A Comparative Study with a 1.5T Tunnel System.

BACKGROUND: Cardiac magnetic resonance imaging (cMRI) has become the non-invasive reference standard for the evaluation of cardiac function and viability. The introduction of open, high-field, 1.0T (HFO) MR scanners offers advantages for examinations of obese, claustrophobic and paediatric patients.The aim of our study was to compare standard cMRI sequences from an HFO scanner and those from a cylindrical, 1.5T MR system. MATERIAL/METHOD: Fifteen volunteers underwent cMRI both in an open HFO and in a cylindrical MR system. The protocol consisted of cine and unenhanced tissue sequences. The signal-to-noise ratio (SNR) for each sequence and blood-myocardium contrast for the cine sequences were assessed. Image quality and artefacts were rated. The location and number of non-diagnostic segments was determined. Volunteers' tolerance to examinations in both scanners was investigated. RESULTS: SNR was significantly lower in the HFO scanner (all p<0.001). However, the contrast of the cine sequence was significantly higher in the HFO platform compared to the 1.5T MR scanner (0.685±0.41 vs. 0.611±0.54; p<0.001). Image quality was comparable for all sequences (all p>0.05). Overall, only few non-diagnostic myocardial segments were recorded: 6/960 (0.6%) by the HFO and 17/960 (1.8%) segments by the cylindrical system. The volunteers expressed a preference for the open MR system (p<0.01). CONCLUSIONS: Standard cardiac MRI sequences in an HFO platform offer a high image quality that is comparable to the quality of images acquired in a cylindrical 1.5T MR scanner. An open scanner design may potentially improve tolerance of cardiac MRI and therefore allow to examine an even broader patient spectrum.