We have further improved this technique through the use of respiratory gated (4D) acquisition, which can reduce blurring caused by respiration motion and resultant artefact at the lung bases [ 27, 28].
BLADE significantly (p < 0.0001) reduced motion and ghosting artefacts and showed improved conspicuity (p = 0.3/0.24), but overall image quality did not differ significantly (inter-observer agreement BLADE κ = 0.89; TSE κ = 0.84).
Spin echo (SE) sequences are less sensitive than gradient echo (GE) to motion and susceptibility artefacts.
Each scan was manually screened for anomalies, motion, and material artefacts.
However, MR has relatively long acquisition times and is therefore sensitive to motion and misregistration artefacts [ 16, 17].
Yet, acquisition time, sensitivity to motion and blurring artefacts did not allow 3D acquisition in all sequences.
Furthermore, the high level of noise present in the PET images, coupled with possible residual motion artefacts and attenuation artefacts [10], might complicate the perfect alignment of the two datasets and therefore increase the chances to introduce additional, anatomy-driven artefacts in the PVC-PET reconstructions.
Independent Component Analysis (ICA) has emerged as a powerful approach, but current extensions to the analysis of group studies suffer from a number of drawbacks: they can be computationally demanding, results are dominated by technical and motion artefacts, and some methods require that time courses be the same for all subjects or that templates be defined to identify common components.
fNIRS data will be preprocessed with HOMER2 (http://www.nmr.mgh.harvard.edu/PMI/resources/homer2/home.htm) converting them into HbO and HbR concentration changes after noise and motion artefact correction [ 55].
Recent technical advances in body MRI, including the 3-T magnetic field, parallel image processing and motion artefact reduction techniques, raise hopes for shorter scan times and increased spatial resolution for detecting early inflammatory changes [28, 39].
