Fetal Cardiovascular MRI - A Systemic Review of the Literature: Challenges, New Technical Developments, and Perspectives.

BACKGROUND: Fetal magnetic resonance imaging (MRI) has become a valuable adjunct to ultrasound in the prenatal diagnosis of congenital pathologies of the central nervous system, thorax, and abdomen. Fetal cardiovascular magnetic resonance (CMR) was limited, mainly by the lack of cardiac gating, and has only recently evolved due to technical developments. METHOD: A literature search was performed on PubMed, focusing on technical advancements to perform fetal CMR. In total, 20 publications on cardiac gating techniques in the human fetus were analyzed. RESULTS: Fetal MRI is a safe imaging method with no developmental impairments found to be associated with in utero exposure to MRI. Fetal CMR is challenging due to general drawbacks (e. g., fetal motion) and specific limitations such as the difficulty to generate a cardiac gating signal to achieve high spatiotemporal resolution. Promising technical advancements include new methods for fetal cardiac gating, based on novel post-processing approaches and an external hardware device, as well as motion compensation and acceleration techniques. CONCLUSION: Newly developed direct and indirect gating approaches were successfully applied to achieve high-quality morphologic and functional imaging as well as quantitative assessment of fetal hemodynamics in research settings. In cases when prenatal echocardiography is limited, e. g., by an unfavorable fetal position in utero, or when its results are inconclusive, fetal CMR could potentially serve as a valuable adjunct in the prenatal assessment of congenital cardiovascular malformations. However, sufficient data on the diagnostic performance and clinical benefit of new fetal CMR techniques is still lacking. KEY POINTS: · New fetal cardiac gating methods allow high-quality fetal CMR.. · Motion compensation and acceleration techniques allow for improvement of image quality.. · Fetal CMR could potentially serve as an adjunct to fetal echocardiography in the future.. CITATION FORMAT: · Knapp J, Tavares de Sousa M, Schönnagel BP. Fetal Cardiovascular MRI - A Systemic Review of the Literature: Challenges, New Technical Developments, and Perspectives. Fortschr Röntgenstr 2022; 194: 841 - 851.

Non-invasive pediatric cardiac imaging-current status and further perspectives.

BACKGROUND: Non-invasive cardiac imaging has a growing role in diagnosis, differential diagnosis, therapy planning, and follow-up in children and adolescents with congenital and acquired cardiac diseases. This review is based on a systematic analysis of international peer-reviewed articles and additionally presents own clinical experiences. It provides an overview of technical advances, emerging clinical applications, and the aspect of artificial intelligence. MAIN BODY: The main imaging modalities are echocardiography, CT, and MRI. For echocardiography, strain imaging allows a novel non-invasive assessment of tissue integrity, 3D imaging rapid holistic overviews of anatomy. Fast cardiac CT imaging new techniques-especially for coronary assessment as the main clinical indication-have significantly improved spatial and temporal resolution in adjunct with a major reduction in ionizing dose. For cardiac MRI, assessment of tissue integrity even without contrast agent application by mapping sequences is a major technical breakthrough. Fetal cardiac MRI is an emerging technology, which allows structural and functional assessment of fetal hearts including even 4D flow analyses. Last but not least, artificial intelligence will play an important role for improvements of data acquisition and interpretation in the near future. CONCLUSION: Non-invasive cardiac imaging plays an integral part in the workup of children with heart disease. In recent years, its main application congenital heart disease has been widened for acquired cardiac diseases.

Intraindividual comparison of 1.5 T and 3 T non-contrast MR angiography for monitoring of aortic root diameters in Marfan patients.

BACKGROUND: Reproducible aortic diameter measurements are crucial for assessment of aortic growth and aneurysm formation in patients with Marfan syndrome. The objective of this study was to perform an intraindividual comparison of aortic measurements at 1.5 T and 3 T using non-contrast magnetic resonance angiography (MRA) in pre-surgical and post-surgical Marfan patients. METHODS: Forty consecutive Marfan patients were retrospectively evaluated by ECG-gated 2D balanced steady-state free precession (bSSFP) MRA at 1.5 T and 3 T after 363 ± 58 days. 24 patients were before and 16 patients after aortic root surgery. Two readers independently measured aortic diameters at seven aortic levels and rated the image quality/image artifacts (1 = poor/severe, 4 = excellent/none). Contrast-to-noise ratio (CNR) and signal intensity slopes between aortic lumen and vessel walls were semiautomatically determined. RESULTS: In pre-surgical Marfan patients, interobserver agreement of aortic root diameter measurements was significantly higher at 3 T compared to 1.5 T (p < 0.05). In post-surgical Marfan patients, image quality and artifacts were significantly worse at 3 T compared to 1.5 T (p < 0.05). CNR was higher at 3 T compared to 1.5 T at all aortic levels. Significantly steeper slopes of signal intensity curves were observed at 3 T at all aortic levels (p < 0.001). CONCLUSIONS: In pre-surgical Marfan patients, non-contrast MRA provides higher reproducibility of aortic diameter measurements at 3 T compared to 1.5 T. In post-surgical Marfan patients, metallic implants result in significantly worse imaging artifacts and reduced image quality at 3 T compared to 1.5 T. Therefore, we propose to monitor the thoracic aorta with non-contrast MRA at 3 T in pre-surgical Marfan patients and at 1.5 T in post-surgical Marfan patients.