Carlos Castillo Passi

All Publications

• Simultaneous 3D aortic lumen and vessel wall imaging at 0.55 T at either systole or diastole MAGNETIC RESONANCE IN MEDICINE Paredes, M., Castillo-Passi, C., Kunze, K. P., Fotaki, A., Littlewood, S., Botnar, R. M., Prieto, C. 2025

  Abstract

  To evaluate the feasibility of a novel, non-contrast enhanced, 3D, simultaneous bright-blood, and black-blood sequence (iT2prep-BOOST) for aortic imaging at 0.55 T at either systole or diastole.Simultaneous contrast-free 3D aortic lumen and vessel wall imaging at 0.55 T is achieved using the recently introduced iT2prep-BOOST framework that interleaves the acquisition of two bright blood images (with inversion recovery T2 preparation [T2prep-IR] and no preparation). To enable either systolic or diastolic aortic imaging, three T2 preparation pulses were investigated-an adiabatic RF pulse and two Malcolm-Levitt (MLEV) pulses (MLEV4 and MLEV8)-to improve image quality in regions with high flow and susceptibility. The proposed approach was evaluated in phantom, 10 healthy subjects and 3 patients with suspected cardiovascular disease. Bright- and black-blood images resulting from the three different T2 preparation pulses were compared both qualitatively and quantitatively, using a 4-point Likert scale for vessel sharpness and presence of blood artifacts. Additionally, the contrast ratio between the lumen and myocardium was computed. Aortic measurements, including the aortic annulus area at systole and diastole, cusp-commissure measurement at the aortic root level during diastole, and aortic diameter at the ascending aortic level during diastole were also performed.Excellent or good image quality scores were obtained for both bright- and black-blood images with iT2prep-BOOST at 0.55 T with all three preparation pulses. The use of MLEV8 T2 preparation scheme improves systolic image quality, reducing the presence of artifacts with a significant difference (p < 0.05) at the mid descending aorta level. This scheme also increases the contrast ratio between aortic lumen and myocardium, compared to the previously used adiabatic RF T2 preparation. The aortic root diameter and area were consistent with values reported in the literature for healthy subjects at 1.5 T.The feasibility of a novel, non-contrast-enhanced, 3D aortic imaging framework for simultaneous bright-blood and black-blood imaging was demonstrated at 0.55 T for either systole or diastole, with a scan time of 7 min. Good image quality scores and aortic measurements in agreement with literature values at 1.5 T were achieved with the MLEV8 T2 preparation. Studies in a larger cohort of healthy subjects and patients with aortopathies are warranted.

  View details for DOI 10.1002/mrm.30611

  View details for Web of Science ID 001513255400001

  View details for PubMedID 40548843

• Highly efficient image navigator based 3D whole-heart cardiac MRA at 0.55T MAGNETIC RESONANCE IN MEDICINE Castillo-Passi, C., Kunze, K. P., Crabb, M. G., Munoz, C., Fotaki, A., Neji, R., Irarrazaval, P., Prieto, C., Botnar, R. M. 2025; 93 (2): 689-698

  Abstract

  To develop and evaluate a highly efficient free-breathing and contrast-agent-free three-dimensional (3D) whole-heart Cardiac Magnetic Resonance Angiography (CMRA) sequence at 0.55T.Free-breathing whole-heart CMRA has been previously proposed at 1.5 and 3T. Direct application of this sequence to 0.55T is not possible due to changes in the magnetic properties of the tissues. To enable free-breathing CMRA at 0.55T, pulse sequence design and acquisition parameters of a previously proposed whole-heart CMRA framework are optimized via Bloch simulations. Image navigators (iNAVs) are used to enable nonrigid respiratory motion-correction and 100% respiratory scan efficiency. Patch-based low-rank denoising is employed to accelerate the scan and account for the reduced signal-to-noise ratio at 0.55T. The proposed approach was evaluated on 11 healthy subjects. Image quality was assessed by a clinical expert (1: poor to 5: excellent) for all intrapericardiac structures. Quantitative evaluation was performed by assessing the vessel sharpness of the proximal right coronary artery (RCA).Optimization resulted in an imaging flip angle of 11 0 ∘ $$ 11{0}^{\circ } $$ , fat saturation flip angle of 18 0 ∘ $$ 18{0}^{\circ } $$ , and six k-space lines for iNAV encoding. The relevant cardiac structures and main coronary arteries were visible in all subjects, with excellent image quality (mean 4 . 9 / 5 . 0 $$ 4.9/5.0 $$ ) and minimal artifacts (mean 4 . 9 / 5 . 0 $$ 4.9/5.0 $$ ), with RCA vessel sharpness ( 50 . 3 % ± 9 . 8 % $$ 50.3\%\pm 9.8\% $$ ) comparable to previous studies at 1.5T.The proposed approach enables 3D whole-heart CMRA at 0.55T in a 6-min scan ( 5 . 9 ± 0 . 7   min $$ 5.9\pm 0.7\;\min $$ ), providing excellent image quality, minimal artifacts, and comparable vessel sharpness to previous 1.5T studies. Future work will include the evaluation of the proposed approach in patients with cardiovascular disease.

  View details for DOI 10.1002/mrm.30316

  View details for Web of Science ID 001412668100017

  View details for PubMedID 39415543

  View details for PubMedCentralID PMC11604836