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Purpose: To develop a neural network architecture for improved calibrationless reconstruction of radial data when no ground truth is available for training. Methods: NLINV‐Net is a model‐based neural network architecture that directly estimates images and coil sensitivities from (radial) k‐space data via nonlinear inversion (NLINV). Combined with a training strategy using self‐supervision via data undersampling (SSDU), it can be used for imaging problems where no ground truth reconstructions are available. We validated the method for (1) real‐time cardiac imaging and (2) single‐shot subspace‐based quantitative T1 mapping. Furthermore, region‐optimized virtual (ROVir) coils were used to suppress artifacts stemming from outside the field of view and to focus the k‐space‐based SSDU loss on the region of interest. NLINV‐Net‐based reconstructions were compared with conventional NLINV and PI‐CS (parallel imaging + compressed sensing) reconstruction and the effect of the region‐optimized virtual coils and the type of training loss was evaluated qualitatively. Results: NLINV‐Net‐based reconstructions contain significantly less noise than the NLINV‐based counterpart. ROVir coils effectively suppress streakings which are not suppressed by the neural networks while the ROVir‐based focused loss leads to visually sharper time series for the movement of the myocardial wall in cardiac real‐time imaging. For quantitative imaging, T1‐maps reconstructed using NLINV‐Net show similar quality as PI‐CS reconstructions, but NLINV‐Net does not require slice‐specific tuning of the regularization parameter. Conclusion: NLINV‐Net is a versatile tool for calibrationless imaging which can be used in challenging imaging scenarios where a ground truth is not available. [ABSTRACT FROM AUTHOR]

Aims: Intravenous iron therapy (IVIT) is known to improve functional status in chronic heart failure (CHF) patients. The exact mechanism is not completely understood. We correlated magnetic resonance imaging (MRI) patterns of T2* iron signal in various organs to systemic iron and exercise capacity (EC) in CHF before and after IVIT. Methods and results: We prospectively analysed 24 patients with systolic CHF for T2* MRI pattern of the left ventricle (LV), small and large intestines, spleen, liver, skeletal muscle, and brain for iron. In 12 patients with iron deficiency (ID), we restored iron deficit by IVIT using ferric carboxymaltose. The effects after 3 months were analysed by spiroergometry and MRI. Patients with vs. without ID showed lower blood ferritin, haemoglobin (76 ± 63 vs. 196 ± 82 μg/L and 12.3 ± 1.1 vs. 14.2 ± 1.1 g/dL, all P < 0.002), and in trend a lower transferrin saturation (TSAT) (19.1 [13.1; 28.2] vs. 25.1 [21.3; 29.1] %, P = 0.05). Spleen and liver iron was lower as expressed by higher T2* value (71.8 [66.4; 93.1] vs. 36.9 [32.9; 51.7] ms, P < 0.002 and 33.5 ± 5.9 vs. 28.8 ± 3.9 ms, and P < 0.03). There was a strong trend for a lower cardiac septal iron content in ID (40.6 [33.0; 57.3] vs. 33.7 [31.3; 40.2] ms, P = 0.07). After IVIT, ferritin, TSAT, and haemoglobin increased (54 [30; 104] vs. 235 [185; 339] μg/L, 19.1 [13.1; 28.2] vs. 25.0 [21.0; 33.7] %, 12.3 ± 1.1 vs. 13.3 ± 1.3 g/L, all P < 0.04). Peak VO2 improved (18.2 ± 4.2 vs. 20.9 ± 3.8 mL/min/kg−1, P = 0.05). Higher peak VO2 at anaerobic threshold was associated with higher blood ferritin, reflecting higher metabolic exercise capacity after therapy (r = 0.9, P = 0.0009). Increase in EC was associated with haemoglobin increase (r = 0.7, P = 0.034). LV iron increased by 25.4% (48.5 [36.2; 64.8] vs. 36.2 [32.9; 41.9] ms, P < 0.04). Spleen and liver iron increased by 46.4 and 18.2%, respectively (71.8 [66.4; 93.1] vs. 38.5 [22.4; 76.9] ms, P < 0.04 and 33.5 ± 5.9 vs. 27.4 ± 8.6 ms, P < 0.007). Iron in skeletal muscle, brain, intestine, and bone marrow remained unchanged (29.6 [28.6; 31.2] vs. 30.4 [29.7; 30.7] ms, P = 0.7, 81.0 ± 6.3 vs. 82.9 ± 9.9 ms, P = 0.6, 34.3 ± 21.4 vs. 25.3 ± 14.1 ms, P = 0.2, 9.4 [7.5; 21.8] vs. 10.3 [6.7; 15.7] ms, P = 0.5 and 9.8 ± 1.5 vs. 13.7 ± 8.9 ms, P = 0.1). Conclusions: CHF patients with ID showed lower spleen, liver, and in trend lower cardiac septal iron. After IVIT, iron signal of the left ventricle as well as spleen and liver increased. Improvement in EC was associated with increase in haemoglobin after IVIT. In ID, liver, spleen, and brain but not heart iron were associated with markers of systemic ID. [ABSTRACT FROM AUTHOR]

Purpose: To develop a free‐breathing myocardial T1$$ {\mathrm{T}}_1 $$ mapping technique using inversion‐recovery (IR) radial fast low‐angle shot (FLASH) and calibrationless motion‐resolved model‐based reconstruction. Methods: Free‐running (free‐breathing, retrospective cardiac gating) IR radial FLASH is used for data acquisition at 3T. First, to reduce the waiting time between inversions, an analytical formula is derived that takes the incomplete T1$$ {\mathrm{T}}_1 $$ recovery into account for an accurate T1$$ {\mathrm{T}}_1 $$ calculation. Second, the respiratory motion signal is estimated from the k‐space center of the contrast varying acquisition using an adapted singular spectrum analysis (SSA‐FARY) technique. Third, a motion‐resolved model‐based reconstruction is used to estimate both parameter and coil sensitivity maps directly from the sorted k‐space data. Thus, spatiotemporal total variation, in addition to the spatial sparsity constraints, can be directly applied to the parameter maps. Validations are performed on an experimental phantom, 11 human subjects, and a young landrace pig with myocardial infarction. Results: In comparison to an IR spin‐echo reference, phantom results confirm good T1$$ {\mathrm{T}}_1 $$ accuracy, when reducing the waiting time from 5 s to 1 s using the new correction. The motion‐resolved model‐based reconstruction further improves T1$$ {\mathrm{T}}_1 $$ precision compared to the spatial regularization‐only reconstruction. Aside from showing that a reliable respiratory motion signal can be estimated using modified SSA‐FARY, in vivo studies demonstrate that dynamic myocardial T1$$ {\mathrm{T}}_1 $$ maps can be obtained within 2 min with good precision and repeatability. Conclusion: Motion‐resolved myocardial T1$$ {\mathrm{T}}_1 $$ mapping during free‐breathing with good accuracy, precision and repeatability can be achieved by combining inversion‐recovery radial FLASH, self‐gating and a calibrationless motion‐resolved model‐based reconstruction. [ABSTRACT FROM AUTHOR]

BACKGROUND: Correction of tetralogy of Fallot (cTOF) often results in pulmonary valve pathology and right ventricular (RV) dysfunction. Reduced exercise capacity in cTOF patients cannot be explained by these findings alone. We aimed to explore why cTOF patients exhibit impaired exercise capacity with the aid of a comprehensive cardiopulmonary exercise testing (CPET) and real-time cardiovascular magnetic resonance exercise testing (CMR-ET) protocol. METHODS: Thirty three cTOF patients and 35 matched healthy controls underwent CPET and CMR-ET in a prospective casecontrol study. Real-time steady-state free precession cine and phase-contrast sequences were obtained during incremental supine in-scanner cycling at 50, 70, and 90 W. RV and left ventricle (LV) volumes and pulmonary blood flow (Qp) were calculated. Differences of CPET and CMR-ET between cTOF versus controls and correlations between CPET and CMR-ET parameters in cTOF were evaluated statistically for all CMR exercise levels using Mann-Whitney U and Spearman rank-order correlation tests. RESULTS: CPET capacity was significantly lower in cTOF than in controls. cTOF patients exhibited not only significantly reduced Qp and RV function but also lower LV function on CMR-ET. Higher CPET values in cTOF correlated with higher Qp (Qp 90 W versus carbon dioxide ventilatory equivalent %: R=-0.519, P<0.05), higher LV-end-diastolic volume indexed to body surface area (LV-end-diastolic volume indexed to body surface area at 50 W versus oxygen uptake in % at maximum exercise on CPET R=0.452, P<0.05), and change in LV ejection fraction (EF; LV-EF at 90 W versus Watt %: r=-0.463, P<0.05). No correlation was found with regard to RV-EF. Significant RV-LV interaction was observed during CMR-ET (RV-EF versus LV-EF at 50 W and 70 W: r=0.66, P<0.02 and r=0.52, P<0.05, respectively). CONCLUSIONS: Impaired exercise capacity in cTOF resulted from a reduction in not only RV, but also LV function. cTOF with good exercise capacity on CPET demonstrated higher LV reserve and pulmonary blood flow during incremental CMR-ET. Apart from RV parameters, CMR-ET-derived LV function could be a valuable tool to stratify cTOF patients for pulmonary valve replacement. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: The purpose of our study was to evaluate magnetic resonance (MR) artifacts related to breast tissue markers in breast imaging procedures.Materials and Methods: In this bicentric prospective ex vivo study 10 different commercially available markers were measured in self-made breast phantoms. Breast tissue markers varying in marker size, composition, and shape were evaluated. MR imaging (MRI) scans were performed on 1.5 Tesla (T) and 3 T scanners from 2 different vendors, using dedicated breast coils. Three different sequences (T1-weighted images with and without fat saturation, T2-weighted images) were acquired in axial and coronal view. Three blinded readers electronically measured the artifact length.Results: All markers caused artifacts in MRI. The largest median artifact length was 10.4 mm, interquartile range (IQR 9.4-11.0 mm), the smallest 4.8 mm (IQR 4.5-5.2 mm). Relative artifact length (quotient artifact length in mm/real physical length of the marker) ranged between 0.9 (IQR 0.9-1.2) and 3.0 (IQR 2.8-3.4). Mean artifact length was higher for metallic markers (10.2 mm; IQR 8.7-11.5 mm) compared to metallic markers with nonmetallic coating (7.7 mm; IQR 6.3-10.2 mm) and nonmetallic marker (7.6 mm; IQR 5.9-10.0 mm); all p < 0.0001. Artifact size was higher in coronal in comparison to axial view; p < 0.05. The results were comparable between the different field strengths, the sites and sequences; p > 0.05. Interobserver agreement was excellent (ntraclass correlation coefficient = 0.83).Conclusion: Artifacts are necessary in the detection and localization of breast tissue markers, but could also limit the interpretation of MRI due to the possibility of masking the residual tumor after biopsy. This artifact size varies among the different clips evaluated. It depends on marker composition and scan direction but is not influenced by image sequence, field strength or scanner type. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular Magnetic Resonance myocardial feature tracking (CMR-FT) is a quantitative technique tracking tissue voxel motion on standard steady-state free precession (SSFP) cine images to assess ventricular myocardial deformation. The importance of left atrial (LA) deformation assessment is increasingly recognized and can be assessed with echocardiographic speckle tracking. However atrial deformation quantification has never previously been demonstrated with CMR. We sought to determine the feasibility and reproducibility of CMR-FT for quantitative derivation of LA strain and strain rate (SR) myocardial mechanics. Methods: 10 healthy volunteers, 10 patients with hypertrophic cardiomyopathy (HCM) and 10 patients with heart failure and preserved ejection fraction (HFpEF) were studied at 1.5 Tesla. LA longitudinal strain and SR parameters were derived from SSFP cine images using dedicated CMR-FT software (2D CPA MR, TomTec, Germany). LA performance was analyzed using 4- and 2-chamber views including LA reservoir function (total strain [εs], peak positive SR [SRs]), LA conduit function (passive strain [εe ], peak early negative SR [SRe]) and LA booster pump function (active strain [εa], late peak negative SR [SRa]). Results: In all subjects LA strain and SR parameters could be derived from SSFP images. There was impaired LA reservoir function in HCM and HFpEF (εs [%]: HCM 22.1 ± 5.5, HFpEF 16.3 ± 5.8, Controls 29.1 ± 5.3, p < 0.01; SRs [s−1]: HCM 0.9 ± 0.2, HFpEF 0.8 ± 0.3, Controls 1.1 ± 0.2, p < 0.05) and impaired LA conduit function as compared to healthy controls (εe [%]: HCM 10.4 ± 3.9, HFpEF 11.9 ± 4.0, Controls 21.3 ± 5.1, p < 0.001; SRe [s−1]: HCM −0.5 ± 0.2, HFpEF −0.6 ± 0.1, Controls −1.0 ± 0.3, p < 0.01). LA booster pump function was increased in HCM while decreased in HFpEF (εa [%]: HCM 11.7 ± 4.0, HFpEF 4.5 ± 2.9, Controls 7.8 ± 2.5, p < 0.01; SRa [s−1]: HCM −1.2 ± 0.4, HFpEF −0.5 ± 0.2, Controls −0.9 ± 0.3, p < 0.01). Observer variability was excellent for all strain and SR parameters on an intra- and inter-observer level as determined by Bland-Altman, coefficient of variation and intraclass correlation coefficient analyses. Conclusions: CMR-FT based atrial performance analysis reliably quantifies LA longitudinal strain and SR from standard SSFP cine images and discriminates between patients with impaired left ventricular relaxation and healthy controls. CMR-FT derived atrial deformation quantification seems a promising novel approach for the study of atrial performance and physiology in health and disease states. [ABSTRACT FROM AUTHOR]

Background: While cardiovascular magnetic resonance (CMR) commonly employs ECG-synchronized cine acquisitions with balanced steady-state free precession (SSFP) contrast at 1.5 T, recent developments at 3 T demonstrate significant potential for T1-weighted real-time imaging at high spatiotemporal resolution using undersampled radial FLASH. The purpose of this work was to combine both ideas and to evaluate a corresponding real-time CMR method at 1.5 T with SSFP contrast. Methods: Radial gradient-echo sequences with fully balanced gradients and at least 15-fold undersampling were implemented on two CMR systems with different gradient performance. Image reconstruction by regularized nonlinear inversion (NLINV) was performed offline and resulted in real-time SSFP CMR images at a nominal resolution of 1.8 mm and with acquisition times of 40 ms. Results: Studies of healthy subjects demonstrated technical feasibility in terms of robustness and general image quality. Clinical applicability with access to quantitative evaluations (e.g., ejection fraction) was confirmed by preliminary applications to 27 patients with typical indications for CMR including arrhythmias and abnormal wall motion. Real-time image quality was slightly lower than for cine SSFP recordings, but considered diagnostic in all cases. Conclusions: Extending conventional cine approaches, real-time radial SSFP CMR with NLINV reconstruction provides access to individual cardiac cycles and allows for studies of patients with irregular heartbeat. [ABSTRACT FROM AUTHOR]

ELLERY, S.,et al.: A New Endocardial“Over-the-Wire” or Stylet-Driven Left Ventricular Lead: First Clinical Experience. Transvenous left ventricular (LV) leads are primarily inserted“over-the-wire” (OTW). However, a stylet-driven (SD) approach may be a helpful alternative. A new polyurethane-coated, unipolar LV lead can be placed either by a stylet or a guide wire, which can be inserted into the lead body from both ends. The multicenter OVID study evaluates the clinical performance of this new steroid- and nonsteroid eluting lead. The primary endpoint is the LV lead implant success rate after identification of the coronary sinus (CS). Secondary endpoints include complication rate, short- and long-term lead characteristics, overall procedure and LV lead placement duration, total fluoroscopy time, and lead handling characteristics ratings. To date, 96 patients with heart failure (68± 9 years old, 76% men) are enrolled. The CS was identified in 95 patients and, in 85 (88.5%), the LV lead was successfully implanted. The final lead positioning was lateral in 41%, posterolateral in 35%, anterolateral in 18%, and great cardiac vein in 6% of patients. In 70%, the 85 successful implantations, both stylet-driven and guide-wire techniques were used, a stylet only was used in 22%, and a guide wire only in 8%. Mean overall duration of 85 successful procedures was 112± 40 minutes, total fluoroscopy time 28± 15 minutes, and the duration of LV lead placement was 35± 29 minutes. During a 3-month follow-up, the loss of LV capture occurred in three and phrenic nerve stimulation in six patients. The mean long-term pacing threshold is 0.8 V/0.5 ms and pacing impedance is 550Ω. The OVID data suggest that these new leads are safe and effective. The choice of both OTW and SD techniques during lead implantation offers greater procedural flexibility.(PACE 2005; 28:S31–S35) [ABSTRACT FROM AUTHOR]

The article focuses on the case of a 67-year-old man who was hospitalized after an acute onset chest pain. Medical imaging like echocardiography and contrast-enhanced computed tomographic angiography shows pericardial effusion, aneurismal dilation of the ascending aorta, and intimal tear that extends into anterior intramural hematoma. It says that a vascular prosthesis was used to replace the supracoronary scending aorta and aortic arch inferior wall and the patient recovers without disability.

Background: Neointimal proliferation resulting in luminal renarrowing is the major cause of restenosis limiting the long-term success of coronary angioplasty in 20 to 30% of patients. Local transfection of the DNA encoding for VEGF has been shown to enhance re-endothelialization and reduce neointimal proliferation in an experimental model. We tested the hypothesis that transfection of the DNA for the receptor of vascular endothelial growth factor VEGF, KDR-flk-1, reduces neointimal proliferation after angioplasty. Methods: In a minipig model, we performed coronary stent implantation, followed by injection of either KDR/flk-1 DNA (200 μg of linearized DNA in a CMV-promotor) or LacZ control in two coronary artery segments per animal in a randomized, blinded protocol (n = 22 animals). Expression of KDR/flk-1 was analyzed using in situ hybridization after 4, 7, and 14 days. Results: In KDR-transfected coronary segments, expression of KDR/flk-1 occurred earlier and to much stronger extent compared to LacZ-transfected segments. After 4 weeks (n = 10) neointimal proliferation and luminal narrowing was significantly reduced in KDR/flk-1 transfected animals. No expression of locally transfected DNA was detected in other organs. Conclusion: The hypothesis is supported, that expression of the VEGF-receptor KDR/flk-1 can be rate-limiting for endothelial regeneration and that its transient overexpression at the time angioplasty can prevent excessive neointimal proliferation resulting in restenosis. [Copyright &y& Elsevier]