Neuroimaging, Volume 1, Issue 2 (June 2026) – 4 articles

Background/Objectives: This study evaluated the reproducibility of brain morphometric measurements obtained with different head coils and acceleration factors on a PET/MR scanner, with the aim of supporting reliability in longitudinal neuroimaging studies following major scanner hardware upgrades and introduction of higher-channel-density coils for improved image quality and shorter acquisition times. Methods: Fifteen healthy subjects underwent MPRAGE imaging on a 3T PET/MR scanner using a 16 channel head/neck coil with acceleration factor 2 and a 32 channel PET-transparent head coil with acceleration factors 2 and 4. Cortical thickness and subcortical volumes were measured with FreeSurfer. We performed correlation analyses to test the association between the values of cortical thickness and subcortical volumes derived from MPRAGE images acquired with either the 16- or the 32 channel coil. Test–retest variability and intraclass correlation coefficient were calculated to assess the reproducibility of the measurements for each brain region generated by each sequence and coil. Results: Cortical thickness and subcortical volume measurements from images acquired with different coils and acceleration factors showed high correlation (R = 0.96–1.00, p < 0.001) between protocols, with median test–retest variability below 4% for cortical thickness and a structure-dependent pattern for subcortical volumes, with higher variability in smaller structures such as the accumbens, reaching approximately 7.9% in cross-coil comparisons. Conclusions: Overall, brain morphometry measurements were reproducible across acquisition conditions. Coils with a higher number of channels were associated with improved signal-to-noise ratio, shorter acquisition times, and maintained quantitative consistency. Full article

Background/Objectives: Autobiographical memories (AMs) are an essential type of memory for our sense of self. A broad network of brain regions supports the retrieval of AMs, encompassing the medial temporal lobe (MTL), medial prefrontal cortex (mPFC), and parietal and visual cortices. However, little is known about how the subjective qualia of these memories relate to the underlying functional networks supporting their retrieval. Methods: AM cues were generated from early and recent life encompassing both object- and location-specific memories. While undergoing functional imaging, participants were cued on to retrieve differing time (remote, recent) and type (object, location) AMs followed by subjective ratings of each memory cued. Results: Functional activation patterns were consistent across the time and type of memory and reflect the existing literature. Functional connectivity analyses were similar across memory age, with only recent memories having greater connectivity compared to remote memories. Subjective qualia moderated the connectivity between regions for both remote and recent memories. Connections from the mPFC were modulated by multiple ratings across memory age, with important recent memories showing a significant negative connection with the hippocampus (p_FDR < 0.05). Conclusions: Subjective qualia mostly modulated the connectivity profile of the mPFC with other visual and MTL regions underlying the mPFC’s importance during retrieval of autobiographical memories. These connections, in relation to differing subjective qualia across memory age, highlight the possible differences in the reinstantiation of AMs. Full article

MaChiP 1.0 used static magnetic resonance imaging (MRI) to identify coexistent idiopathic intracranial hypertension (IIH) and spontaneous intracranial hypotension (SIH) in Chiari I malformation (CM-I), improving etiologic characterization. This Protocol/Perspective paper presents MaChiP 2.0 as a testable, artificial intelligence (AI)-integrated imaging roadmap for acquired Chiari I malformation (CM-I), intended to support the differentiation between congenital and acquired tonsillar descent and to guide leak-localization imaging in suspected spontaneous intracranial hypotension (SIH). Building on the structural foundation of MaChiP 1.0, this framework outlines how dynamic craniospinal imaging tools, including phase-contrast magnetic resonance imaging (PC-MRI) and displacement encoding with stimulated echoes (DENSE), may be combined with conventional morphologic markers to refine imaging evaluation. It further describes the potential use of currently available artificial intelligence (AI) methods for segmentation, cerebrospinal fluid (CSF) flow quantification, and imaging biomarker assessment. Noninvasive magnetic resonance (MR)-based techniques are proposed as first-line approaches for leak detection, while digital subtraction myelography (DSM) and computed tomography myelography (CTM) remain the reference standards when initial imaging is inconclusive. Full article

Background/Objectives: MRI-guided neurovascular interventions could benefit from lower-field systems due to reduced magnetic and radiofrequency hazards. However, safety and practical visibility of commonly used neurointerventional devices at 0.55 T remain insufficiently characterized. We evaluated magnetic field interactions, RF-induced heating, and qualitative device visibility in 11 commercially available and commonly used neurovascular devices on a 0.55 T MRI system. Methods: Eleven devices, including stent retrievers, guidewires, catheters, and one embolization implant, were tested at 0.55 T. Magnetostatic interactions were quantified using the American Society for Testing and Materials (ASTM)-guided deflection methods for translational force (ASTM-F2052) and a two-string suspension apparatus for torque (adapted from Stoianovici et al.). RF-induced heating was measured in an in vitro perfused cerebral vessel phantom using a 15 min high-specific absorption rate spin echo sequence under static and flow conditions. Qualitative device visibility was assessed using a turbo spin echo (TSE) and balanced steady-state free precession (bSSFP) imaging on each device individually. Results: Eight of eleven devices passed the translational force test, while three devices (D, E, and G), containing significant ferromagnetic components, failed with deflection angles > 45°. Eight devices passed torque testing, remaining below the critical threshold in all rotation positions; three devices (D, G, and J) failed by exceeding the 54° criterion, including one guidewire and two devices with braided/coiled metallic structures. Under static conditions, RF-induced heating ranged from negligible to 10.4 °C (maximum in device D) and generally decreased under flow; in the flow configuration, temperature rise remained below 2 °C for 6/11 devices. Qualitative imaging performance differed by sequence, with bSSFP enabling improved delineation of device structure (best for devices A, C, and H), whereas devices D, E, F, and J produced extensive signal voids that precluded reliable visualization in both sequences. Overall, three devices satisfied all safety criteria while remaining clearly visible under MRI. Conclusions: Devices that pass safety thresholds at 0.55 T can serve as candidates for further sequence optimization and preclinical workflow development, enabling the design of low-SAR, device-compatible imaging protocols tailored for neurointerventional workflows. These results provide key safety data supporting the feasibility of MR-guided neurovascular procedures at 0.55 T. Full article