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Acute myocarditis (AM) and hypertensive heart disease (HHD) have different pathophysiological backgrounds, thus potentially showing distinct patterns of altered myocardial deformation. Therefore, CMR left ventricular (LV) feature tracking (FT)- based strain parameters were indexed to myocardial mass index (LVMi) in order to evaluate potential additional value in the differentiation among AM, HHD, and healthy volunteers (HV) compared to non-indexed conventional strain.Patients with AM (n = 43) and HHD (n = 28) underwent CMR at 3T. 61 HV served as controls. Cine imaging-based FT-strain analysis was performed and natural strain (nStrain) values were evaluated for gender and age specific differences in HV. Strain parameters were indexed to LVMi yielding ratio Strain (rStrain). These were evaluated for their discriminatory accuracy compared to nStrain values.There were significant differences in nStrain between genders (p0.05), but not between age groups in HV. Circumferential strains differentiated best between HV and AM, reaching an area under the curve (AUC) of 0.86 (female) and 0.81 (male), yielding 93 (72) % sensitivity and 55 (75) % specificity. In discriminating between HV and HHD as well as AM and HHD, longitudinal strains outperformed all other parameters with AUCs of 1.00 (female)/ 0.92 (male) and 0.90 (female)/ 0.74 (male), respectively. Sensitivity and specificity levels of 100 %/ 100 % (female) and 91 %/ 72 % (male) for HV versus AM as well as 82 %/ 71 % (female) and 91%/ 57 % (male) for AM versus HHD could be demonstrated. The usage of rStrains significantly increased the AUC for circumferential and radial strains in male patients.rStrain provided additional value in the differentiation of diseases with increased LVM. As rStrain is derived from standard native cine imaging, such parameters can be time efficiently and reliably calculated, giving them the potential to be a powerful addition to the currently developing multiparametric native diagnostic approaches.

Assessing endocardial strain using a single 13N-ammonia positron emission tomography (PET) scan would be clinically useful, given the association between ischemia and myocardial deformation. However, no software has been developed for strain analysis using PET. We evaluated the clinical potential of feature tracking-derived strain values measured using PET, based on associations with the myocardial flow reserve (MFR). This retrospective study included 95 coronary artery disease patients who underwent myocardial 13N-ammonia PET. Semi-automatic measurements were made using a feature-tracking technique during myocardial cine imaging, and values were calculated using a 16-segment model. Adenosine-stressed global circumferential strain (CS) and global longitudinal strain (LS) values were compared with global MFR values. Stressed and resting global strain values were also compared. Global strain values were significantly lower in 39 patients with abnormal MFRs [< 2.0] than in 56 patients with normal MFRs [≥ 2.0]. The global CS values in the stressed state were significantly decreased than the resting state values in patients with abnormal MFRs. This study applied endocardial feature-tracking to 13N-ammonia PET, and the results suggested that blood flow and myocardial motility could be clinically assessed in ischemic patients using a single PET scan.

Purpose Hybrid MRI-linear accelerator systems (MR-linacs) allow for the incorporation of MR images with high soft-tissue contrast into the radiation therapy procedure prior to, during, or post irradiation. This allows not only for the optimization of the treatment planning, but also for real-time monitoring of the tumor position using cine MRI, from which intrafractional motion can be compensated. Fast imaging and accurate tumor tracking are crucial for effective compensation. This study investigates the application of cine MRI with a radial acquisition scheme on a low-field MR-linac to accelerate the acquisition rate and evaluates the effect on tracking accuracy. Methods An MR sequence using tiny golden-angle radial k-space sampling was developed and applied to cine imaging on patients with liver tumors on a 0.35 T MR-linac. Tumor tracking was assessed for accuracy and stability from the cine images with increasing k-space undersampling factors. Tracking was achieved using two different auto-segmentation algorithms: a deformable image registration B-spline similar to that implemented on the MR-linac and a convolutional neural network approach known as U-Net. Results Radial imaging allows for increased temporal resolution with reliable tumor tracking, although tracking robustness decreases as temporal resolution increases. Additional acquisition-based artifacts can be avoided by reducing the angle increment using tiny golden-angles. The U-net algorithm was found to have superior auto-segmentation metrics compared to B-spline. U-net was able to track two well-defined tumors, imaged with just 30 spokes per image (10.6 frames per second), with an average Dice coefficient ≥ 83%, Hausdorff distance ≤ 1.4 pixel, and mean contour distance ≤ 0.5 pixel. Conclusions Radial acquisitions are commonplace in dynamic imaging; however, in MR-guided radiotherapy, robust tumor tracking is also required. This study demonstrates the in vivo feasibility of tumor tracking from radially acquired images on a low-field MR-linac. Radial imaging allows for decreased image acquisition times while maintaining robust tracking. The U-net algorithm can track a tumor with higher accuracy in images with undersampling artifacts than a conventional deformable B-spline algorithm and is a promising tool for tracking in MR-guided radiation therapy.

Cardiac CINE magnetic resonance imaging is the gold-standard for the assessment of cardiac function. Imaging accelerations have shown to enable 3D CINE with left ventricular (LV) coverage in a single breath-hold. However, 3D imaging remains limited to anisotropic resolution and long reconstruction times. Recently deep learning has shown promising results for computationally efficient reconstructions of highly accelerated 2D CINE imaging. In this work, we propose a novel 4D (3D + time) deep learning-based reconstruction network, termed 4D CINENet, for prospectively undersampled 3D Cartesian CINE imaging. CINENet is based on (3 + 1)D complex-valued spatio-temporal convolutions and multi-coil data processing. We trained and evaluated the proposed CINENet on in-house acquired 3D CINE data of 20 healthy subjects and 15 patients with suspected cardiovascular disease. The proposed CINENet network outperforms iterative reconstructions in visual image quality and contrast (+ 67% improvement). We found good agreement in LV function (bias ± 95% confidence) in terms of end-systolic volume (0 ± 3.3 ml), end-diastolic volume (− 0.4 ± 2.0 ml) and ejection fraction (0.1 ± 3.2%) compared to clinical gold-standard 2D CINE, enabling single breath-hold isotropic 3D CINE in less than 10 s scan and ~ 5 s reconstruction time.

Cardiovascular disease (CVD), including coronary artery disease, heart failure, cardiomyopathy, and myocarditis, accounts for 32% of deaths and remains the leading cause of death worldwide (17.9 million per year; WHO, 2019). In cardiology Magnetic resonance imaging (MRI) is an essential clinical imaging tool because it provides excellent soft-tissue contrast. MR examination can be used to examine non-invasively various parameters of the heart, providing information on, for example, functionality, blood flow, or tissue composition. Depending on the intended application, different cardiac MRI techniques are utilized. For example, cine MRI is suitable for visualizing cardiac motion and regional wall motion abnormalities, while the assessment of the progression of myocarditis can be achieved with the use of T1 mapping. Of disadvantage to many techniques are the long examination times mainly due to physiological motion such as breathing. To ensure that image quality is not compromised by motion artifacts, the breathhold strategy is commonly used in clinical practice. But for a complete examination, the patients must manage several instructed breath-holding phases, which can often be difficult for the sick, elderly, or children. Therefore, methods have been developed that allow cardiac MR examination under free breathing. Often these approaches are based on an additional measurement of an MR-navigator, which provides information about the respiratory motion state. However, the MR-navigator is not suitable for continuous measurements because its acquisition interrupts the steady-state during the measurement. A novel alternative for a motion surrogate is the pilot tone (PT). The PT is an additional RF signal introduced into the scanner, which can be extracted from the acquired MR data during the measurement. The intensity of the scale-free signal changes depending on the respiratory motion and can, therefore, be used as a motion surrogate. Nevertheless, quantitative motion information is required for motion correction. In this thesis, a new PT-based method for respiratory motion correction for cardiac MRI was developed. Using phantom- and in vivo data, it was demonstrated that motion correction using the PT leads to an improvement in image quality and accuracy of quantitative parameters compared with uncorrected images. The temporal stability of the PT was shown for at least 50 min. Subject-specific motion models were derived from a calibration scan, that allow to convert the qualitative PT into a quantitative signal providing information about respiratory motion. Furthermore, a comparison of the PT with other motion surrogates was performed. For a 3D MR scan, retrospective motion correction using the PT improved the visibility of the coronary arteries similar to the MR-navigator. Thereafter, a novel prospective PT-based motion correction approach was developed, which enables slice tracking during the running sequence. The quantitative PT was used to adapt the slice position during the measurement to ensure the current imaging slice follows the respiratory motion of the heart. Motion artifacts in functional cine images with Cartesian acquisition scheme could be strongly reduced with this prospective motion correction approach. The contrast-to-noise ratio with respect to motion artifacts and also the sharpness of the endocardium improved significantly compared with the uncorrected images. Furthermore, left ventricular blood pool areas were determined, and there was no significant difference between the reference breathhold method and the presented motion-corrected free-breathing approach. Similar improvements were achieved for quantitative T1-mapping of the myocardium. Here a radial acquisition scheme was used for data acquisition. Without motion correction respiratory motion led to an overestimation of T1 values compared to breathhold data, which was successfully corrected with the PT-based approach. The presented results demonstrate that PT-based respiratory motion correction is robust, accurate, and versatile, and thus may enable future developments such as high-resolution imaging strategies under free-breathing., Kardiovaskuläre Erkrankungen (CVD), einschließlich Koronarer Herzkrankheit, Herzinsuffizienz, Kardiomyopathie und Myokarditis sind für 32% aller Todesfälle verantwortlich und bleiben weltweit die häufigste Todesursache (17,9 Millionen pro Jahr; WHO, 2019). In der Kardiologie ist die Magnetresonanztomographie (MRT) wegen des hervorragenden Weichteilkontrasts ein wichtiges klinisches Bildgebungsinstrument zur Differentialdiagnose. Mit einer MR-Untersuchung können nicht-invasiv verschiedene Parameter des Herzens untersucht werden, die z.B. Aufschluss über die Funktionsfähigkeit, den Blutfluss oder die Gewebezusammensetzung geben. Dabei werden je nach Anwendungsgebiet spezielle kardiale MRT-Techniken eingesetzt. Zur Darstellung von Herzbewegungen und regionalen Herzwandbewegungsstörungen eignet sich beispielsweise die Cine-MRT, während die Beurteilung des Verlaufs einer Myokarditis mit Hilfe des T1-Mappings möglich ist. Von Nachteil für viele Techniken ist jedoch die für MR-Untersuchungen typisch lange Aufnahmedauer pro Bild, die hauptsächlich auf physiologische Bewegungen zurückzuführen ist. Um sicherzustellen, dass die Bildqualität nicht durch Bewegungsartefakte beeinträchtigt wird, kommt in der klinischen Praxis häufig die Atemanhaltestrategie zum Einsatz, bei der die Atembewegung unterdrückt wird. Für eine vollständige Untersuchung müssen die PatientInnen jedoch mehrere instruierte Atemanhaltephasen bewältigen, was für Kranke, ältere Menschen oder Kinder oft schwierig sein kann. Daher wurden Methoden entwickelt, die eine kardiale MR-Untersuchung unter freier Atmung ermöglichen. Häufig basieren diese Ansätze auf einer zusätzlichen Messung eines MR-Navigators, welcher Informationen über den Atembewegungszustand liefert. Für eine kontinuierliche Messung ist der MR-Navigator jedoch ungeeignet, da seine Erfassung die Bildaufnahme unterbricht. Eine neue Alternative für ein Bewegungssurrogat ist der Pilotton (PT). Der PT ist ein zusätzliches in den Scanner eingebrachtes RF-signal, welches während der Messung aus den aufgenommenen MR-Daten extrahiert werden kann. Die Intensität des nicht skalierten Signals ändert sich in Abhängigkeit von der Atembewegung. Daher kann der PT als Bewegungssurrogat verwendet werden. Quantitative Bewegungsinformationen, die für eine Bewegungskorrektur genutzt werden könnten, wurden mit dem PT bisher noch nicht gewonnen. In dieser Dissertation wurde erstmals eine PT-basierte Atembewegungskorrektur für die kardiale MRT entwickelt. Auf Basis von Phantom- und in vivo-Daten konnte nachgewiesen werden, dass die Bewegungskorrektur mit dem PT zu einer Verbesserung der Bildqualität im Vergleich zu unkorrigierten Bildern führt. Die zeitliche Stabilität des PT wurde für ca. 50 Minuten gezeigt. Aus einem Kalibrierungsscan wurden personenspezifische Bewegungsmodelle abgeleitet, die es ermöglichen, den qualitativen PT in ein quantitatives Signal umzuwandeln, das Informationen über die Atembewegung liefert. Darüber hinaus wurde ein Vergleich des PT mit anderen Bewegungssurrogaten durchgeführt. Bei einem 3D-MR-Scan verbesserte die retrospektive Bewegungskorrektur mit dem PT die Sichtbarkeit der Koronararterien ähnlich wie mit dem MR-Navigator. Ferner wurde ein prospektiver PT-basierter Ansatz zur Bewegungskorrektur entwickelt, der schon während der Messung, eine atemangepasste Schichtmitführung (Slice Tracking) ermöglicht. Bewegungsartefakte in funktionellen Cine-Aufnahmen mit kartesischem Aufnahmeschema konnten mit dieser prospektiven Bewegungskorrektur stark reduziert werden. Das Kontrast-Rausch-Verhältnis in Bezug auf Bewegungsartefakte und auch die Kantenschärfe des Endokards verbesserten sich im Vergleich zu den unkorrigierten Bildern signifikant. Darüber hinaus wurden die linksventrikulären Blutpoolflächen bestimmt, wobei es keinen signifikanten Unterschied zwischen der Referenzmethode und dem vorgestellten bewegungskorrigierten Ansatz gab. Ähnliche Verbesserungen wurden bei der quantitativen Messmethode T1-Mapping erzielt. Hier wurde ein radiales Akquisitionsschema f¨ur die Datenerfassung verwendet. Ohne Bewegungskorrektur führte die Atembewegung zu einer Überschätzung der T1-Werte im Vergleich zu den Referenzdaten, was mit der Anwendung der PT-basierten Methode korrigiert werden konnte. Die vorgestellten Ergebnisse zeigen, dass die PT-basierte Atembewegungskorrektur robust, akkurat und vielseitig einsetzbar ist und damit zukünftigen Entwicklungen, wie beispielsweise hochauflösenden Bildgebungsstrategien unter freier Atmung den Weg ebnet.

Purpose In this work, we explore the use of multiband (MB) balanced steady‐state free precession (bSSFP) with blipped‐controlled aliasing in parallel imaging (CAIPI), which avoids the issues of altered frequency response associated with RF phase cycling, and show its application to accelerating cardiac cine imaging. Methods Blipped and RF‐cycled CAIPI were implemented into a retrospective‐gated segmented cine multiband bSSFP sequence. The 2 methods were compared at 3T using MB2 to demonstrate the effect on frequency response. Further data (4 subjects) were acquired at both 1.5T and 3T collecting 12‐slice short axis stacks using blipped‐CAIPI with MB acceleration factors of 1–4. The impact on SNR and contrast was evaluated along with g‐factors at different accelerations. Results Data acquired with blipped‐CAIPI multiband bSSFP up to factor 4 yielded functional cine data with good SNR and contrast, while reliably keeping dark‐band artefacts clear of the heart at 1.5T. SAR limits the maximum MB acceleration, particularly at 3T, where minimum TR increase is problematic and leakage artefacts are more prevalent. Mean g‐factors across the heart were measured at 1.00, 1.06, and 1.12 for MB2–MB4, whereas blood‐pool SNR measures (end‐diastole) decreased by 11.8, 21.5, and 36.9%; ultimately LV‐myocardium CNR remained sufficient at 1.5T with values ranging: 15.6, 13.4, 11.9, and 9.6 (MB1–MB4). Conclusion Blipped‐CAIPI multiband bSSFP can be used in cardiovascular applications without affecting the frequency response because of controlled aliasing and can be readily incorporated into segmented cine acquisitions without adding any additional constraints because of phase cycling requirements. The method was used to collect full ventricular coverage within a single breath‐hold.

Purpose To develop a free-running framework for 3D isotropic simultaneous myocardial T1/T2 mapping and cine imaging. Methods Continuous data acquisition with 3D golden angle radial trajectory is used in conjunction with T2 preparation of varying echo times and inversion recovery (IR) pulses to enable simultaneous myocardial T1/T2 mapping and cine imaging. Data acquisition is retrospectively synchronized with ECG signal, and 1D respiratory self-navigation signal is extracted from the k-space center of all radial spokes. Respiratory binning is performed based on the estimated respiratory signal, enabling estimation and correction of 3D translational respiratory motion. Using high-dimensionality patch-based undersampled reconstruction with dictionary-based low-rank inversion, whole-heart T1/T2 maps and cine images can be generated with 2 mm isotropic spatial resolution. The proposed technique was validated in a standardised phantom and ten healthy subjects in comparison to conventional 2D imaging techniques. Results Phantom T1 and T2 measurements demonstrated good agreement with 2D spin echo techniques. Septal T1 estimated with the proposed technique (1185.6 ± 49.8 ms) was longer than with a conventional breath-hold 2D IR-prepared sequence (1044.3 ± 26.7 ms), whereas T2 measurements (47.6 ± 2.5 ms) were lower than a breath-hold 2D gradient spin echo sequence (52.0 ± 1.8 ms). Precision of the proposed 3D mapping was higher than conventional 2D mapping techniques. Ejection fraction measured with the proposed 3D approach (63.8 ± 6.8%) agreed well with conventional breath-held multi-slice 2D cine (62.3 ± 6.4%). Conclusions The proposed technique provides co-registered 3D T1/T2 maps and cine images with isotropic spatial resolution from a single free-breathing scan, thereby providing a promising imaging tool for whole-heart myocardial tissue characterization and functional evaluation.

Purpose Balanced steady-state free precession (bSSFP) left atrial (LA) cine suffers from off-resonance artifacts, particularly in the pulmonary veins (PVs). Linear combination or multiple-acquisition SSFP (MA-SSFP) effectively removes banding but greatly increases scan time. We hypothesized that MA-SSFP with interleaved radial undersampling, where each phase-cycling is acquired with an interleaved set of radial projections, would improve image quality of LA cine with a small increase of scan time and streak artefacts. Methods Undersampled radial MA-SSFP with and without interleaving was compared with fully sampled radial bSSFP by means of simulations, phantoms, and in vivo imaging. Ten healthy subjects were imaged on a 3T scanner, with bSSFP and MA-SSFP cine of the left atrium, and B0-mapping. Images were assessed (1 = worst, 5 = best) by 2 independent readers, with respect to 5 qualitative criteria and apparent signal-to-noise ratio. Results In healthy subjects, off-resonance differed from the right inferior PVs to the LA cavity by 163 Hz ± 73 Hz at 3T. Compared with fully sampled radial bSSFP, interleaved radial MA-SSFP significantly improved image quality with respect to off-resonance artifacts (3.8 ± 0.6 versus 2.3 ± 1.0; P = 0.005), PV conspicuity (2.8 ± 1.0 versus 4.3 ± 0.5; P = 0.005), and the number of visualized PVs (1.7 ± 0.4 versus 0.9 ± 0.7; P = 0.008), although with greater streak artifacts (3.4 ± 0.4 versus 4.9 ± 0.2; P = 0.004) and lower measured apparent signal-to-noise ratio (24 ± 9 versus 69 ± 36; P = 0.002). Flow artifacts were similar. Interleaved radial MA-SSFP reduced streaking artifacts and increased apparent signal-to-noise ratio versus noninterleaved radial. Conclusions Interleaved radial MA-SSFP cine reduces banding artifacts with an acceptable increase of scan time and streak artifacts. The proposed technique improves the LA and PV visualization in bSSFP cine imaging.

Technical guidelines for magnetic resonance imaging (MRI) of the small bowel (SB) in the setting of inflammatory bowel diseases (IBDs) were detailed in a 2017 consensus issued by European Society of Gastrointestinal and Abdominal Radiology (ESGAR) and European Society of Pediatric Radiology (ESPR); however, MRI for non-IBD conditions was not addressed. Hence, we performed a systematic review collecting researches on SB MRI for non-IBDs. The literatures were then divided into morphologic group and functional group. Information about the MRI techniques, gastrointestinal preparation, and details of cine-MRI protocols was extracted. We found that a 1.5 T MRI system, prone positioning, and MR enterography were frequently utilized in clinical practice. Gadolinium contrast sequences were routinely implemented, while diffusion-weighted imaging (DWI) was much less performed. The gastrointestinal preparation varied throughout the studies. No uniform protocols for cine imaging could be established. SB MRI examinations for non-IBDs are far from standardized, especially for functional studies. Recommendations for standard parameters in cine-MRI sequences are difficult to make due to lack of evidentiary support. MRI investigations in non-IBD conditions are needed and the standardization of non-IBD imaging in clinical practice is required.

Introduction Effective management of intrafraction motion is critical to the success of MR-guided radiation therapy (MR-gRT) of abdominal or thoracic tumors. Recent developments have proposed the use of cine MRI to monitor motion and 4D-MRI to aid in the reconstruction of dose actually delivered to patients. The present work aims to develop and perform preliminary testing of an imaging framework capable of simultaneously acquiring orthogonal plane cine imaging and isotropic resolution 4D-MRI volumes using super-resolution methods. Methods A pulse sequence was developed to acquire time-locked cine imaging in sagittal and coronal planes while additionally acquiring 4D-MRIs in both planes simultaneously. Isotropic resolution 4D-MRIs were reconstructed by combining information from the orthogonal volumes using super-resolution methods. This method was tested in phantoms and in liver cancer patients. Results Simultaneous cine imaging in sagittal and coronal planes allowed monitoring of respiratory motion and an accurate binning of concurrently acquired 4D imaging slices into the appropriate respiratory phases. The super-resolution reconstruction methods improved the resolution of the 4D-MRI along both of the low-resolution slice-select dimensions. Conclusions The development and preliminary testing of an imaging framework capable of acquiring simultaneous orthogonal cine imaging and super-resolution 4D-MRI was performed. The promising results merit further investigation for use in dose reconstruction during MR-guided radiation therapy.

Rationale and Objectives Diagnosis of cardiac amyloidosis (CA) on cardiac magnetic resonance (CMR) can be challenging and quantitative indexes are relevant to further characterize the myocardium. We hypothesize that the relative myocardial enhancement measured from pre and post contrast cine imaging provides diagnostic information for CA in the setting of left ventricular hypertrophy (LVH). Materials and Methods Patients with LVH referred to our center and control subjects with normal CMR were retrospectively included. Percentage of myocardial enhancement (percentage ME) was obtained from pre and post contrast (5 minutes) cine sequences. Post contrast myocardial T1 and LGE extent were also recorded. Results Twenty-one patients with CA, 25 patients with non-amyloid left ventricular myocardial hypertrophy (CH) and 20 controls with normal CMR were analyzed. Percentage ME was significantly higher in CA patients (200% (174–238)) than in CH patients (122% (88–151); p = 0.0001) and control patients (104% (90–149); p = 0.0001). Percentage ME was significantly correlated with the LGE extent (Rho Spearman coefficient = 0.66; p = 0.0001) and with the post contrast myocardial T1 (Rho Spearman coefficient = −0.61; p = 0.0001). With a cutoff value of 152%, the sensitivity and specificity of percentage ME for detection of CA were 90% and 80%, respectively. Conclusion Percentage ME obtained from pre and post contrast cine imaging is correlated to LGE extent and myocardial T1 and may represent an additional diagnostic parameter to consider CA in patients with LVH.

Background and objective: To evaluate the reliability of compressed-sensing (CS) real-time single-breath-hold cine imaging for quantification of right ventricular (RV) function and volumes in congenital heart disease (CHD) patients in comparison with the standard multi-breath-hold technique. Methods: Sixty-one consecutive CHD patients (mean age = 22.2 ± 9.0 (SD) years) were prospectively evaluated during either the initial work-up or after repair. For each patient, two series of cine images were acquired: first, the reference segmented multi-breath-hold steady-state free-precession sequence (SSFPref), including a short-axis stack, one four-chamber slice, and one long-axis slice, then, an additional real-time compressed-sensing single-breath-hold sequence (CSrt) providing the same slices. Two radiologists independently assessed the image quality and RV volumes for both techniques, which were compared using the Wilcoxon test and paired Student’s t test, Bland–Altman, and linear regression analyses. The visualization of wall-motion disorders and tricuspid-regurgitation-related signal voids were also analyzed. Results: The mean acquisition time for CSrt was 22.4 ± 6.2 (SD) s (95% CI: 20.8–23.9 s) versus 442.2 ± 89.9 (SD) s (95% CI: 419.2–465.2 s) for SSFPref (p &lt, 0.001). The image quality of CSrt was diagnostic in all examinations and was mostly rated as good (n = 49/61, 80.3%). There was a high correlation between SSFPref and CSrt images regarding RV ejection fraction (49.8 ± 7.8 (SD)% (95% CI: 47.8–51.8%) versus 48.7 ± 8.6 (SD)% (95% CI: 46.5–50.9%), respectively, r = 0.94) and RV end-diastolic volume (192.9 ± 60.1 (SD) mL (95% CI: 177.5–208.3 mL) versus 194.9 ± 62.1 (SD) mL (95% CI: 179.0–210.8 mL), respectively, r = 0.98). In CSrt images, tricuspid-regurgitation and wall-motion disorder visualization was good (area under receiver operating characteristic curve (AUC) = 0.87) and excellent (AUC = 1), respectively. Conclusions: Compressed-sensing real-time cine imaging enables, in one breath hold, an accurate assessment of RV function and volumes in CHD patients in comparison with standard SSFPref, allowing a substantial improvement in time efficiency.

Background Assessment of gastric function in humans has relied on modalities with varying degrees of invasiveness, which are usually limited to the evaluation of single aspects of gastric function, thus requiring patients to undergo a number of often invasive tests for a full clinical understanding. Therefore, the development of a non-invasive tool able to concurrently assess multiple aspects of gastric function is highly desirable for both research and clinical assessments of gastrointestinal (GI) function. Recently, technological advances in magnetic resonance imaging (MRI) have provided new tools for dynamic (or "cine") body imaging. Such approaches can be extended to GI applications. Methods In the present work, we propose a non-invasive assessment of gastric function using a four-dimensional (4D, volumetric cine imaging), free-breathing MRI sequence with gadolinium-free contrast enhancement achieved through a food-based meal. In healthy subjects, we successfully estimated multiple parameters describing gastric emptying, motility, and peristalsis propagation patterns. Key results Our data demonstrated non-uniform kinematics of the gastric wall during peristaltic contraction, highlighting the importance of using volumetric data to derive motility measures. Conclusions & inferences MRI has the potential of becoming an important clinical and gastric physiology research tool, providing objective parameters for the evaluation of impaired gastric function.

Purpose To develop and validate a new cardiac self-gating algorithm using blind source separation for 2D cine steady-state free precession (SSFP) imaging. Methods A standard cine SSFP sequence was modified so that the center point of k-space was sampled with each excitation. The center points of k-space were processed by 4 blind source separation methods, and used to detect heartbeats and assign k-space data to appropriate time points in the cardiac cycle. The proposed self-gating technique was prospectively validated in 8 patients against the standard electrocardiogram (ECG)-gating method by comparing the cardiac cycle lengths, image quality metrics, and ventricular volume measurements. Results There was close agreement between the cardiac cycle length using the ECG- and self-gating methods (bias 0.0 bpm, 95% limits of agreement ±2.1 bpm). The image quality metrics were not significantly different between the ECG- and self-gated images. The ventricular volumes, stroke volumes, and mass measured from self-gated images were all comparable with those from ECG-gated images (all biases Conclusion The self-gating method yielded comparable cardiac cycle length, image quality, and ventricular measurements compared with standard ECG-gated cine imaging. It may simplify patient preparation, be more robust when there is arrhythmia, and allow cardiac gating at higher field strengths.

Purpose To evaluate the reliability of a real-time compressed sensing (CS) cine sequence for the detection of left ventricular wall motion disorders after myocardial infarction in comparison with the reference steady-state free precession cine sequence. Materials and Methods One hundred consecutive adult patients referred for either initial work-up or follow-up by cardiac magnetic resonance (CMR) in the context of myocardial infarction were prospectively included. There were 77 men and 23 women with a mean age of 63.12 ± 11.3 (SD) years (range: 29–89 years). Each patient underwent the reference segmented multi-breath-hold steady-state free precession cine sequence including one short-axis stack and both vertical and horizontal long-axis slices (SSFPref) and the CS real-time single-breath-hold evaluated sequence (CSrt) providing the same slices. Wall motion disorders were independently and blindly assessed with both sequences by two radiologists, using the American Heart Association left ventricle segmentation. Paired Wilcoxon signed-rank test was used to search for differences in wall motion disorders conspicuity between both sequences and receiver operating characteristic curve (ROC) analysis was performed to assess the diagnosis performance of CSrt sequence using SSFPref as the reference method. Results Each patient had at least one cardiac segment with wall motion abnormality on SSFPref and CSrt images. The 1700 segments analyzed with SSFPref were classified as normokinetic (360/1700; 21.2%), hypokinetic (783/1700; 46.1%), akinetic (526/1700; 30.9%) or dyskinetic (31/1700; 1.8%). Sensitivity and specificity of the CS sequence were 99.6% (95% CI: 99.1–99.9%) and 99.7% (95% CI: 98.5–100%), respectively. Area under ROC of CSrt diagnosis performance was 0.997 (95% CI: 0.993–0.999). Conclusion CS real-time cine imaging significantly reduces acquisition time without compromising the conspicuity of left ventricular -wall motion disorders in the context of myocardial infarction.

Cardiovascular magnetic resonance (CMR) has emerged as a key modality to assess nonischemic cardiomyopathies. Its ability to detect cardiac morphology and function with fast cine imaging, myocardial edema with T2-based techniques, and fibrosis with late gadolinium enhancement techniques has enabled noninvasive characterization of cardiac tissue, thus helping clinicians assess cardiovascular risk and determine the most effective management strategy. Active investigations into parametric imaging techniques will further expand the potential clinical applications of CMR for cardiac tissue characterization. This review discusses the use of CMR techniques in characterizing the major morphofunctional phenotypes of nonischemic cardiomyopathies.

Purpose Acutely infarcted native T1 (native T1AI) and extracellular volume (ECVAI) could quantify myocardial injury after acute myocardial infarction (AMI). Therefore, we sought to further explore their association with left ventricular (LV) remodeling during follow-up. Methods 56 ST-segment-elevation MI patients were prospectively recruited and completed acute and 3-month cardiac magnetic resonance scans. T1 mapping, late gadolinium enhancement and cine imaging were performed to measure native T1AI, ECVAI, infarct size and LV global function, respectively. LV remodeling was evaluated as the change in LV end-diastolic volume index (△EDV) at follow-up scan compared with baseline. Results In acute scan, 37 patients (66.07 %) had microvascular obstruction (MVO). The native T1AI did not significantly differ between patients with or without MVO (1482.0 ± 80.6 ms vs. 1469.0 ± 71.6 ms, P = 0.541). However, ECVAI in patients without MVO was lower than that in patients with MVO (49.60 ± 8.57 % vs. 58.53 ± 8.62 %, P = 0.001). The native T1AI only correlated with △EDV in patients without MVO (rmvo- = 0.495, P = 0.031); while ECVAI was associated with △EDV in all patients (rmvo- = 0.665, P = 0.002; rmvo+ = 0.506, P = 0.001; rall patients = 0.570, P Conclusion As a promising parameter for early risk stratification after AMI, ECVAI is associated with LV remodeling during follow-up; while native T1AI may be feasible when MVO is absent.

Cardiac magnetic resonance (MR) imaging is one of the most rigorous form of imaging to assess cardiac function in vivo. Strain analysis allows comprehensive assessment of diastolic myocardial function, which is not indicated by measuring systolic functional parameters using with a normal cine imaging module. Due to the small heart size in mice, it is not possible to perform proper tagged imaging to assess strain. Here, we developed a novel deep learning approach for automated quantification of strain from cardiac cine MR images. Our framework starts by an accurate localization of the LV blood pool center-point using a fully convolutional neural network (FCN) architecture. Then, a region of interest (ROI) that contains the LV is extracted from all heart sections. The extracted ROIs are used for the segmentation of the LV cavity and myocardium via a novel FCN architecture. For strain analysis, we developed a Laplace-based approach to track the LV wall points by solving the Laplace equation between the LV contours of each two successive image frames over the cardiac cycle. Following tracking, the strain estimation is performed using the Lagrangian-based approach. This new automated system for strain analysis was validated by comparing the outcome of these analysis with the tagged MR images from the same mice. There were no significant differences between the strain data obtained from our algorithm using cine compared to tagged MR imaging. Furthermore, we demonstrated that our new algorithm can determine the strain differences between normal and diseased hearts.

In real-time (RT) cardiac cine imaging, a stack of 2D slices is collected sequentially under free-breathing conditions. A complete heartbeat from each slice is then used for cardiac function quantification. The inter-slice respiratory mismatch can compromise accurate quantification of cardiac function. Methods based on principal components analysis (PCA) have been proposed to extract the respiratory signal from RT cardiac cine, but these methods cannot resolve the inter-slice sign ambiguity of the respiratory signal. In this work, we propose a fully automatic sign correction procedure based on the similarity of neighboring slices and correlation to the center-of-mass curve. The proposed method is evaluated in eleven volunteers, with ten slices per volunteer. The motion in a manually selected region-of-interest (ROI) is used as a reference. The results show that the extracted respiratory signal has a high, positive correlation with the reference in all cases. The qualitative assessment of images also shows that the proposed approach can accurately identify heartbeats, one from each slice, belonging to the same respiratory phase. This approach can improve cardiac function quantification for RT cine without manual intervention., Comment: IEEE ISBI 2020, International Symposium on Biomedical Imaging

Myocardial strain is an important measure of cardiac function and can be assessed on cardiac magnetic resonance (MR) through the current gold standard of breath-held segmented steady-state free precession (SSFP) cine imaging. Novel free-breathing techniques have been validated for volumetry and systolic function, allowing for evaluation of sicker and younger children who cannot reliably hold their breath. It is unclear whether strain measurements can be reliably performed on free-breathing, motion-corrected, re-binning cine images. To compare strain analysis from motion-corrected retrospective re-binning images to the breath-held SSFP cine images to explore their validity. Twenty-five children and young adults, ages (2.1–18.6 years) underwent breath-held and motion-corrected retrospective re-binning cine techniques during the same MR examination on a 1.5-tesla magnet. We measured endocardial end-systolic global circumferential strain and endocardial averaged segmental strain using commercial software (MEDIS QStrain 2.1). We used Pearson correlation coefficients to test agreement across techniques. Analysis was possible in all 25 breath-held and motion-corrected retrospective re-binning studies. Global circumferential strain and endocardial averaged segmental strain obtained by motion-corrected retrospective re-binning compared favorably to breath-held studies. Global circumferential strain linear regression models demonstrated acceptable agreement, with coefficients of determination of 0.75 for breath-held compared to motion-corrected retrospective re-binning (P

PURPOSE: To provide high-resolution cardiac T(1) mapping of various cardiac phases and cine imaging within a single breath-hold using continuous golden ratio-based radial acquisition and model-based iterative image reconstruction. METHODS: Data acquisition was performed continuously using golden ratio-based radial sampling and multiple inversion pulses were applied independent of the heart rate. Native T(1) maps of diastole and systole were reconstructed with in-plane resolution of 1.3 × 1.3 mm(2) using model-based iterative image reconstruction. Cine images with 30 cardiac phases were reconstructed from the same data using kt-SENSE. The method was evaluated in a commercially available T(1) phantom and 10 healthy subjects. In vivo T(1) assessment was carried out segment-wise. RESULTS: Evaluation in the phantom demonstrated accurate T(1) times (R(2) > 0.99) and insensitivity to the heart rate. In vivo T(1) values did not differ between systole and diastole, and T(1) times assessed by the proposed approach were longer than measured with a modified Look-Locker inversion recovery (MOLLI) sequence, except for lateral segments. Cine images had a consistent dark-blood contrast and functional assessment was in agreement with assessment based on Cartesian cine scans (difference in ejection fraction: 0.26 ± 2.65%, P = 0.65). CONCLUSION: The proposed approach provides native T(1) maps of diastole and systole with high spatial resolution and cine images simultaneously within 16 s, which could strongly improve the scan efficiency.