Balanced steady‐state free precession thoracic imaging with half‐radial dual‐echo readout on smoothly interleaved archimedean spirals

Abstract

Purpose To investigate the prospects of a minimal‐TR half‐radial dual‐echo balanced steady‐state free precession (bSSFP) acquisition for high‐resolution and artifact‐free thoracic imaging at 1.5T. Methods Feasibility of bSSFP imaging using isotropic half‐radial dual‐echo (hr‐de) projections with TE1/TE2/TR of 0.12/1.18/1.39 ms acquired along Archimedean spiral trajectories was demonstrated for phantoms and in vivo thorax scans at 1.5T. The centered‐out projection offers an ultra‐short echo (UTE) comparable to contemporary spoiled gradient echo (SPGR) UTE radial acquisitions used for the assessment of chest morphology. Signal intensities of hr‐de‐bSSFP were measured and compared to UTE‐SPGR in a phantom and for parenchyma and blood in vivo and compared to theory. Results For the lung parenchyma and the blood, hr‐de‐bSSFP provided more than 4 times higher signal intensity than contemporary UTE‐SPGR imaging. The measured hr‐de‐bSSFP and UTE‐SPGR signal ratios were in the agreement with theoretically simulated values. Overall, the very short TR of hr‐de‐bSSFP successfully mitigated off‐resonance artifacts offering high‐quality breath‐hold thoracic imaging at isotropic resolution of 1.7 mm. The application of a smooth interleaved spiral trajectory for half‐radial readouts improved the robustness of hr‐de‐bSSFP to cardiac motion. Conclusion Thoracic hr‐de‐bSSFP offers artifact‐free chest images with considerably improved signal intensity as compared to contemporary UTE‐SPGR imaging at 1.5T.

3D Magnetic Resonance Spirometry

“…'Real-time' 4D-CT would obviously be favored for 3D Spirometry but, contrary to 4D-CT, retrospectively gated MRI is safe for the patient in terms of ionizing radiation, and the number of motion gates is not limited (14 in Jahani et al 36 and 32 here). Furthermore, the final quality of motion corrected UTE images and the quantity of landmarks observable in the lung with MRI tend to be more and more similar to what can be obtained in motion corrected CT 38,39 .…”

3D phase‐resolved functional lung ventilation MR imaging in healthy volunteers and patients with chronic pulmonary disease

“…Fourth, in comparison to 3D UTE/zero echo time (ZTE) 14‐16,18,23,48,49 or 3D bSSFP 50 pulmonary imaging, the used prototype stack‐of‐stars pulse sequence with golden angle increment possesses a longer TE and therefore achieves in general reduced SNR and resolution with the above‐mentioned techniques. Supporting Information Figure shows comparison of morphological images for a healthy volunteer using a prototype stack‐of‐stars sequence with asymmetric readout (TE = 0.39 ms) and the proposed stack‐of‐stars sequence with symmetric readout (TE = 0.81 ms).…”

Repeatability of dynamic 3D phase‐resolved functional lung (PREFUL) ventilation MR Imaging in patients with chronic obstructive pulmonary disease and healthy volunteers

“…In recent years, extensive development of FD MRI has included improving spatial/temporal resolution, sequence design and postprocessing, and developing a whole-lung technique. [13][14][15][16][17][18][19] Two-dimensional phase-resolved functional lung (PREFUL) MRI 15 is an FD-based technique that was introduced to assess regional ventilation and perfusion dynamics within a single acquisition. Repeatability and validation studies of 2D PREFUL to reference standards have been performed to facilitate the use of 2D PREFUL in clinical routine.…”