No abstract

The SEMAC technique can mitigate artifact caused by metallic dental materials for T1w-SE imaging.

The conventional Fourier-transform-based spin-echo sequence with a view angle tilting gradient during data acquisition can correct the in-plane distortion induced by a chemical shift or B0 field inhomogeneity. However, when extended for 3D applications, alternate k-space sampling can be beneficial for reducing the lengthy scan time. As spiral trajectories have high k-space acquisition efficiency, we investigated the applicability of spiral trajectory on a spin-echo view angle tilting pulse sequence. Computer simulations and phantom and in vivo experiments were performed to validate the usage of spiral readout gradients in the presence of a view angle tilting gradient. The results show that as long as the readout time is comparable to Cartesian readout, the resulting images have similar quality.

Purpose: To reduce irregular respiratory motion-induced artifacts in free-breathing prospective navigator-triggered three-dimensional (3D) MR cholangiopancreatography (MRCP).Materials and Methods: A reference respiration model was estimated from the first-five respiration periods during the initial navigator scan. With the navigator information acquired before and after triggering, the un-acquired diaphragm position during the actual imaging was interpolated using the amplitude-scaled reference model. Craniocaudal translational motion during imaging was retrospectively corrected using the estimated diaphragm position. T2-weighted 3D MRCP data were acquired from 17 healthy volunteers. For quantitative analysis, contrastto-noise ratio (CNR) and relative contrast (RC) of the biliary tree and gallbladder were compared using the paired t-test. Results:The CNR and RC of the biliary tree and gallbladder were significantly higher (P < 0.05) in the maximum intensity projection images after motion compensation. Conclusion:The proposed algorithm can be an effective tool to reduce the irregular respiratory motion-induced artifacts in 3D MRCP imaging.

Results demonstrate that MRT can generate adequate 3D images using the MOV images. Various reconstruction methods in tomosynthesis were readily adapted, while allowing other tomosynthesis reconstruction algorithms to be incorporated. A reformatted reconstruction process was incorporated for applications relevant to MR imaging.