Aim: Echo-planar imaging is a common technique used in functional magnetic resonance imaging (fMRI); however, it suffers from image distortion and signal loss because of large susceptibility effects that are related to the phase-encoding direction of the scan. Despite this relation, the majority of neuroimaging studies has not considered the influence of phase-encoding direction. Here, we aimed to clarify how phase-encoding direction can affect the outcome of an fMRI connectivity study of schizophrenia (SCZ).
Methods: Resting-state fMRI using anterior to posterior (A-P) and posterior to anterior (P-A) directions was used to examine 25 patients with SCZ and 37 matched healthy controls (HC). We conducted a functional connectivity (FC) analysis using independent component analysis and performed three group comparisons: (i) A-P versus P-A (all participants); (ii) SCZ versus HC for the A-P and P-A datasets; and (iii) the interaction between phase-encoding direction and participant group.
Results: The estimated FC differed between the two phase-encoding directions in areas that were more extensive than those where signal loss has been reported. Although FC in the SCZ group was lower than that in the HC group for both directions, the A-P and P-A conditions did not exhibit the same specific pattern of differences. Further, we observed an interaction between participant group and the phase-encoding direction in the left temporoparietal junction and left fusiform gyrus.
Conclusion: Phase-encoding direction can influence the results of FC studies. Thus, appropriate selection and documentation of phase-encoding direction will be important in future resting-state fMRI studies.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1111/pcn.12677 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Local Gradients of Functional Connectivity Enable Precise Fingerprinting of Infant Brains During Dynamic Development.
bioRxiv
December 2024
Department of Radiology and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Brain functional connectivity patterns exhibit distinctive, individualized characteristics capable of distinguishing one individual from others, like fingerprint. Accurate and reliable depiction of individualized functional connectivity patterns during infancy is crucial for advancing our understanding of individual uniqueness and variability of the intrinsic functional architecture during dynamic early brain development, as well as its role in neurodevelopmental disorders. However, the highly dynamic and rapidly developing nature of the infant brain presents significant challenges in capturing robust and stable functional fingerprint, resulting in low accuracy in individual identification over ages during infancy using functional connectivity.
View Article and Find Full Text PDFMicrostructural Characteristics of Cervical Spinal Cord Using High Angular Resolution Diffusion Imaging (HARDI) and Tractography in Healthy Subjects.
Clin Neuroradiol
December 2024
Université Lyon I, Université Claude Bernard, Lyon, France.
Purpose: This study aimed to characterize spinal cord microstructure in healthy subjects using high angular resolution diffusion imaging (HARDI) and tractography.
Methods: Forty-nine healthy subjects (18-50 years, divided into 2 age groups) were included in a prospective study. HARDI of the cervical spinal cord were acquired using a 3T MRI scanner with: 64 directions, b‑value: 1000s/mm, reduced field-of-view (zonally magnified oblique multi-slice), and opposed phase-encoding directions.
Impact Assessment of Systemic Geometric Distortion in 1.5T Magnetic Resonance Imaging Simulation through Three-dimensional Geometric Distortion Phantom on Dosimetric Accuracy for Magnetic Resonance Imaging-only Prostate Treatment Planning.
J Med Phys
September 2024
Division of Diagnostic Radiology, Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
Article Synopsis
- MRI-only radiotherapy helps reduce registration errors that could lead to incorrect dose delivery, but systematic geometric distortion (SGD) from factors like magnetic field inhomogeneity must be addressed.
- The study assessed SGD in 1.5T MRI simulations using a 3D geometric phantom and analyzed its effects on dosimetric accuracy for ten prostate cancer patients treated with volumetric modulated arc radiotherapy (VMAT).
- Results showed that SGD increased with distance from the isocenter, and while dosimetric accuracy was generally high (under 2% error for most structures), the bladder and rectum exhibited exceptions, underscoring the need for SGD assessment in quality assurance before treatment planning.
3D distortion-free, reduced FOV diffusion-prepared gradient echo at 3 T.
Magn Reson Med
October 2024
School of Biomedical Engineering and Imaging Sciences, King's College London, London, UK.
Purpose: To develop a 3D distortion-free reduced-FOV diffusion-prepared gradient-echo sequence and demonstrate its application in vivo for diffusion imaging of the spinal cord in healthy volunteers.
Methods: A 3D multi-shot reduced-FOV diffusion-prepared gradient-echo acquisition is achieved using a slice-selective tip-down pulse in the phase-encoding direction in the diffusion preparation, combined with magnitude stabilizers, centric k-space encoding, and 2D phase navigators to correct for intershot phase errors. The accuracy of the ADC values obtained using the proposed approach was evaluated in a diffusion phantom and compared to the tabulated reference ADC values and to the ADC values obtained using a standard spin echo diffusion-weighted single-shot EPI sequence (DW-SS-EPI).
Value of Spinal Cord Diffusion Imaging and Tractography in Providing Predictive Factors for Tumor Resection in Patients with Intramedullary Tumors: A Pilot Study.
Cancers (Basel)
August 2024
Faculté de Médecine Lyon-Est, Université Claude Bernard Lyon I, 69100 Villeurbanne, France.
This pilot study aimed to investigate the interest of high angular resolution diffusion imaging (HARDI) and tractography of the spinal cord (SC) in the management of patients with intramedullary tumors by providing predictive elements for tumor resection. Eight patients were included in a prospective study. HARDI images of the SC were acquired using a 3T MRI scanner with a reduced field of view.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!