Mesoscale Brain Mapping: Bridging Scales and Modalities in Neuroimaging - A Symposium Review.

Advances in the spatiotemporal resolution and field-of-view of neuroimaging tools are driving mesoscale studies for translational neuroscience. On October 10, 2023, the Center for Mesoscale Mapping (CMM) at the Massachusetts General Hospital (MGH) Athinoula A. Martinos Center for Biomedical Imaging and the Massachusetts Institute of Technology (MIT) Health Sciences Technology based Neuroimaging Training Program (NTP) hosted a symposium exploring the state-of-the-art in this rapidly growing area of research.

Influence of peripheral axon geometry and local anatomy on magnetostimulation chronaxie.

Rapid switching of magnetic resonance imaging (MRI) gradient fields induces electric fields that can cause peripheral nerve stimulation (PNS) and so accurate characterization of PNS is required to maintain patient safety and comfort while maximizing MRI performance. The minimum magnetic gradient amplitude that causes stimulation, the PNS threshold, depends on intrinsic axon properties and the spatial and temporal properties of the induced electric field. The PNS strength-duration curve is widely used to characterize simulation thresholds for periodic waveforms and is parameterized by the chronaxie and rheobase.

Experimental validation of a PNS-optimized whole-body gradient coil.

Purpose: Peripheral nerve stimulation (PNS) limits the usability of state-of-the-art whole-body and head-only MRI gradient coils. We used detailed electromagnetic and neurodynamic modeling to set an explicit PNS constraint during the design of a whole-body gradient coil and constructed it to compare the predicted and experimentally measured PNS thresholds to those of a matched design without PNS constraints.

Methods: We designed, constructed, and tested two actively shielded whole-body Y-axis gradient coil winding patterns: YG1 is a conventional symmetric design without PNS-optimization, whereas YG2's design used an additional constraint on the allowable PNS threshold in the head-imaging landmark, yielding an asymmetric winding pattern.

Prediction of experimental cardiac magnetostimulation thresholds using pig-specific body models.

Purpose: Modern high-amplitude gradient systems can be limited by the International Electrotechnical Commission 60601-2-33 cardiac stimulation (CS) limit, which was set in a conservative manner based on electrode experiments and E-field simulations in uniform ellipsoidal body models. Here, we show that coupled electromagnetic-electrophysiological modeling in detailed body and heart models can predict CS thresholds, suggesting that such modeling might lead to more detailed threshold estimates in humans. Specifically, we compare measured and predicted CS thresholds in eight pigs.

Measurement of magnetostimulation thresholds in the porcine heart.

Purpose: Powerful MRI gradient systems can surpass the International Electrotechnical Commission (IEC) 60601-2-33 limit for cardiac stimulation (CS), which was determined by simple electromagnetic simulations and electrode stimulation experiments. Only a few canine studies measured magnetically induced CS thresholds in vivo and extrapolating them to human safety limits can be challenging.

Methods: We measured cardiac magnetostimulation thresholds in 10 healthy, anesthetized pigs using capacitors discharged into a flat spiral coil to produce damped sinusoidal waveforms with effective stimulus duration t  = 0.

Structured Reporting in Radiology: what do radiologists think and does RANZCR have a role in implementation.

Introduction: The Royal Australian and New Zealand College of Radiologists (RANZCR) established a working group to explore how the college should engage with the future development of structured radiology reporting in our region, particularly in the context of a broader move to digital healthcare. Phase 1 of the project surveyed college members and affiliated interest groups about how they are using structured reporting currently and might like it to evolve.

Methods: Member and interest group questionnaires were based on previously published studies and posted to the Survey Monkey platform.

Development and validation of a simplified serotyping ELISA based on monoclonal antibodies for the diagnosis of foot-and-mouth disease virus serotypes O, A, C and Asia 1.

This study describes the development and validation of a simplified enzyme-linked immunosorbent assay (ELISA) for the detection and discrimination of foot-and-mouth disease virus (FMDV) serotypes O, A, C and Asia 1. The multiplex ELISA was designed using selected, type-specific monoclonal antibodies (MAbs) coated onto ELISA plates as catching antibodies and a unique pan-FMDV MAb (1F10) as detector conjugate. Capture MAbs with the broadest intratypic reactivity were selected for each of the four FMDV serotypes by screening large panels of candidate MAbs with a wide spectrum of representative FMDV isolates.

Forward multiple scattering dominates speckle decorrelation in whole-blood flowmetry using optical coherence tomography.

Quantitative blood flow measurements using optical coherence tomography (OCT) have a wide potential range of medical research and clinical applications. Flowmetry based on the temporal dynamics of the OCT signal may have the ability to measure three-dimensional flow profiles regardless of the flow direction. State-of-the-art models describing the OCT signal temporal statistics are based on dynamic light scattering (DLS), a model which is inherently limited to single scattering regimes.

Accurate hybrid template-based and MR-based attenuation correction using UTE images for simultaneous PET/MR brain imaging applications.

Background: Attenuation correction is one of the most crucial correction factors for accurate PET data quantitation in hybrid PET/MR scanners, and computing accurate attenuation coefficient maps from MR brain acquisitions is challenging. Here, we develop a method for accurate bone and air segmentation using MR ultrashort echo time (UTE) images.

Methods: MR UTE images from simultaneous MR and PET imaging of five healthy volunteers was used to generate a whole head, bone and air template image for inclusion into an improved MR derived attenuation correction map, and applied to PET image data for quantitative analysis.

From simultaneous to synergistic MR-PET brain imaging: A review of hybrid MR-PET imaging methodologies.

Simultaneous Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) scanning is a recent major development in biomedical imaging. The full integration of the PET detector ring and electronics within the MR system has been a technologically challenging design to develop but provides capacity for simultaneous imaging and the potential for new diagnostic and research capability. This article reviews state-of-the-art MR-PET hardware and software, and discusses future developments focusing on neuroimaging methodologies for MR-PET scanning.

Sexual Dimorphism of Resting-State Network Connectivity in Healthy Ageing.

Objectives: The onset of many illnesses is confounded with age and sex. Increasing age is a risk factor for the development of many illnesses, and sexual dimorphism influences brain anatomy, function, and cognition. Here, we examine frequency-specific connectivity in resting-state networks in a large sample (n = 406) of healthy aged adults.

Surveillance in Germline TP53 Mutation Carriers Utilizing Whole-Body Magnetic Resonance Imaging.

This prospective study of surveillance strategies uses a whole-body screening program, including whole-body magnetic resonance imaging, in carriers of germline mutations in

White matter integrity of the medial forebrain bundle and attention and working memory deficits following traumatic brain injury.

Background And Objective: The medial forebrain bundle (MFB) contains ascending catecholamine fibers that project to the prefrontal cortex (PFC). Damage to these fibers following traumatic brain injury (TBI) may alter extracellular catecholamine levels in the PFC and impede attention and working memory ability. This study investigated white matter microstructure of the medial MFB, specifically the supero-lateral branch (slMFB), following TBI, and its association with performance on attention and working memory tasks.

ASPREE-NEURO study protocol: A randomized controlled trial to determine the effect of low-dose aspirin on cerebral microbleeds, white matter hyperintensities, cognition, and stroke in the healthy elderly.

Rationale Cerebral microbleeds seen on brain magnetic resonance imaging are markers of small vessel disease, linked to cognitive dysfunction and increased ischemic and hemorrhagic stroke risk. Observational studies suggest that aspirin use may induce cerebral microbleeds, and associated overt intracranial hemorrhage, but this has not been definitively resolved. Aims ASPREE-NEURO will determine the effect of aspirin on cerebral microbleed development over three years in healthy adults aged 70 years and over, participating in the larger 'ASPirin in Reducing Events in the Elderly (ASPREE)' primary prevention study of aspirin.

Recognising pitfalls in assessment of tumours by diffusion-weighted MRI: a pictorial essay.

Diffusion-weighted imaging (DWI) has become an integral part of MRI. Knowledge of the basic principles of DWI and its pitfalls are imperative in the proper application of this technique. We illustrate potential pitfalls of DWI in oncologic imaging.

A phase Ib/II translational study of sunitinib with neoadjuvant radiotherapy in soft-tissue sarcoma.

Background: Preoperative radiotherapy (RT) is commonly used to treat localised soft-tissue sarcomas (STS). Hypoxia is an important determinant of radioresistance. Whether antiangiogenic therapy can 'normalise' tumour vasculature, thereby improving oxygenation, remains unknown.

Recovery of viral RNA and infectious foot-and-mouth disease virus from positive lateral-flow devices.

Foot-and-mouth disease Virus (FMDV) is an economically important, highly contagious picornavirus that affects both wild and domesticated cloven hooved animals. In developing countries, the effective laboratory diagnosis of foot-and-mouth disease (FMD) is often hindered by inadequate sample preservation due to difficulties in the transportation and storage of clinical material. These factors can compromise the ability to detect and characterise FMD virus in countries where the disease is endemic.

Seminal vesicle intrafraction motion analysed with cinematic magnetic resonance imaging.

Purpose: This study analyses seminal vesicle displacement relative to the prostate and in relation to treatment time.

Method: A group of eleven patients undergoing prostate cancer radiotherapy were imaged with a continuous 3 T cine-MRI in the standard treatment setup position. Four images were recorded every 4 seconds for 15 minutes in the sagittal plane and every 6.

Multiparametric 3T MRI in the evaluation of intraglandular prostate cancer: correlation with histopathology.

Introduction: Prostate cancer is common and may be treated immediately or managed conservatively by observation. We sought to determine how reliable multiparametric MRI is in the detection of intraprostatic prostate cancer and what role it has in risk stratification.

Methods: The histology from 38 whole mount prostate specimens was compared with preoperative multiparametric 3T MRI studies with an endorectal receiver coil in place.

Detecting lesions after traumatic brain injury using susceptibility weighted imaging: a comparison with fluid-attenuated inversion recovery and correlation with clinical outcome.

The development and utilization of newer neuroimaging modalities provides the capability to more accurately detect the extent of pathology after TBI. The current study examined the ability of susceptibility-weighted imaging (SWI) to detect lesions after TBI as well as the relationship to subsequent clinical outcome. The performance of SWI was compared to that of fluid-attenuated inversion recovery (FLAIR).

Evidence-based guideline for the written radiology report: methods, recommendations and implementation challenges.

The written radiology report is the dominant method by which radiologists communicate the results of diagnostic and interventional imaging procedures. It has an important impact on decisions about further investigation and management. Its form and content can be influential in reducing harm to patients and mitigating risk for practitioners but varies markedly with little standardisation in practice.

New technologies to diagnose and monitor infectious diseases of livestock: challenges for sub-Saharan Africa.

Using foot-and-mouth disease (FMD) as an example, this review describes new tools that can be used to detect and characterise livestock diseases. In recent years, molecular tests that can detect and characterise pathogens in a diverse range of sample types have revolutionised laboratory diagnostics. In addition to use in centralised laboratories, there are opportunities to locate diagnostic technologies close to the animals with suspected clinical signs.

Efficient production of foot-and-mouth disease virus empty capsids in insect cells following down regulation of 3C protease activity.

Foot-and-mouth disease virus (FMDV) is a significant economically and distributed globally pathogen of Artiodactyla. Current vaccines are chemically inactivated whole virus particles that require large-scale virus growth in strict bio-containment with the associated risks of accidental release or incomplete inactivation. Non-infectious empty capsids are structural mimics of authentic particles with no associated risk and constitute an alternate vaccine candidate.