PURPOSE: To generate phase images with free of motion-induced artifact and susceptibility-induced distortion using 3D radial ultrashort TE (UTE) MRI.MATERIALS AND METHODS: The field map was theoretically derived by solving Laplace's equation with appropriate boundary conditions, and used to simulate the image distortion in conventional spin-warp MRI. Manufacturer's 3D radial imaging sequence was modified to acquire maximum number of radial spokes in a given time, by removing the spoiler gradient and sampling during both rampup and rampdown gradient. Spoke direction randomly jumps so that a readout gradient acts as a spoiling gradient for the previous spoke. The custom raw data was reconstructed using a homemade image reconstruction software, which is programmed using Python language. The method was applied to a phantom and in-vivo human brain and abdomen. The performance of UTE was compared with 3D GRE for phase mapping. Local phase mapping was compared with T₂* mapping using UTE.RESULTS: The phase map using UTE mimics true field-map, which was theoretically calculated, while that using 3D GRE revealed both motion-induced artifact and geometric distortion. Motion-free imaging is particularly crucial for application of phase mapping for abdomen MRI, which typically requires multiple breathold acquisitions. The air pockets, which are caught within the digestive pathway, induce spatially varying and large background field. T₂* map, that was calculated using UTE data, suffers from non-uniform T₂* value due to this background field, while does not appear in the local phase map of UTE data.CONCLUSION: Phase map generated using UTE mimicked the true field map even when non-zero susceptibility objects were present. Phase map generated by 3D GRE did not accurately mimic the true field map when non-zero susceptibility objects were present due to the significant field distortion as theoretically calculated. Nonetheless, UTE allows for phase maps to be free of susceptibility-induced distortion without the use of any post-processing protocols.
Abdomen ; Artifacts ; Boidae ; Brain ; Humans ; Image Processing, Computer-Assisted ; Magnetic Resonance Imaging ; Methods

Background and Objectives: There is little data about cardiac geometry in highly trained young athletes, especially female specific changes. We investigated gender difference on exercise induced cardiac remodeling (EICR) in highly trained university athletes. Methods: A total of 1,185 university athletes divided into 2 groups; female (n=497, 22.0±2.3 years) vs. male (n=688, 22.6±2.4 years). Remodeling of the left ventricle (LV), left atrium (LA), right ventricle (RV), and any cardiac chamber were compared. Results: LV, LA, RV, and any remodeling was found in 156 (13.2%), 206 (17.4%), 82 (6.9%), and 379 athletes (31.9%), respectively. LV, LA, and any remodeling were more common in male than female athletes (n=53, 12.1% vs. n=103, 15.5%, p=0.065), (n=65, 13.1% vs. n=141, 20.5%, p<0.001), (n=144, 30.0% vs. n=235, 34.2%, p=0.058), respectively, whereas RV remodeling was significantly more common in female than male athletes (n=56, 11.3% vs.n=26, 3.8%, p<0.001). Interestingly, the development of LV, LA, and RV remodeling were not overlapped in many of athletes, suggesting different mechanism of EICR according to cardiac chamber. Various predictors including sports type, heart rate, muscle mass, fat mass, body surface area, and training time were differently involved in cardiac remodeling, and there were gender differences of these predictors for cardiac remodeling. Conclusions EICR was common in both sex and was independently developed among cardiac chambers in highly trained university athletes. LV and LA remodeling were common in males, whereas RV remodeling was significantly more common in females demonstrating gender difference in EICR. The present study also demonstrated gender difference in the predictors of EICR.

Background and Objectives: There is little data about cardiac geometry in highly trained young athletes, especially female specific changes. We investigated gender difference on exercise induced cardiac remodeling (EICR) in highly trained university athletes. Methods: A total of 1,185 university athletes divided into 2 groups; female (n=497, 22.0±2.3 years) vs. male (n=688, 22.6±2.4 years). Remodeling of the left ventricle (LV), left atrium (LA), right ventricle (RV), and any cardiac chamber were compared. Results: LV, LA, RV, and any remodeling was found in 156 (13.2%), 206 (17.4%), 82 (6.9%), and 379 athletes (31.9%), respectively. LV, LA, and any remodeling were more common in male than female athletes (n=53, 12.1% vs. n=103, 15.5%, p=0.065), (n=65, 13.1% vs. n=141, 20.5%, p<0.001), (n=144, 30.0% vs. n=235, 34.2%, p=0.058), respectively, whereas RV remodeling was significantly more common in female than male athletes (n=56, 11.3% vs.n=26, 3.8%, p<0.001). Interestingly, the development of LV, LA, and RV remodeling were not overlapped in many of athletes, suggesting different mechanism of EICR according to cardiac chamber. Various predictors including sports type, heart rate, muscle mass, fat mass, body surface area, and training time were differently involved in cardiac remodeling, and there were gender differences of these predictors for cardiac remodeling. Conclusions EICR was common in both sex and was independently developed among cardiac chambers in highly trained university athletes. LV and LA remodeling were common in males, whereas RV remodeling was significantly more common in females demonstrating gender difference in EICR. The present study also demonstrated gender difference in the predictors of EICR.