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The ability to perceive and feel another person' pain as if it were one's own pain, e.g., pain empathy, is related to brain activity in the “pain-matrix” network. A non-core region of this network in Dorsolateral Prefrontal Cortex (DLPFC) has been suggested as a modulator of the attentional-cognitive dimensions of pain processing in the context of pain empathy. We conducted a neurofeedback experiment using real-time functional magnetic resonance imaging (rt-fMRI-NF) to investigate the association between activity in the left DLPFC (our neurofeedback target area) and the perspective assumed by the participant (“first-person”/“Self” or “third-person”/“Other” perspective of a pain-inducing stimulus), based on a customized pain empathy task. Our main goals were to assess the participants' ability to volitionally modulate activity in their own DLPFC through an imagery task of pain empathy and to investigate into which extent this ability depends on feedback. Our results demonstrate participants' ability to significantly modulate brain activity of the neurofeedback target area for the “first-person”/”Self” and “third-person”/”Other” perspectives. Results of both perspectives show that the participants were able to modulate (with statistical significance) the activity already in the first run of the session, in spite of being naïve to the task and even in the absence of feedback information. Moreover, they improved modulation throughout the session, particularly in the “Self” perspective. These results provide new insights on the role of DLPFC in pain and pain empathy mechanisms and validate the proposed protocol, paving the way for future interventional studies in clinical populations with empathic deficits.

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Abstract-Orthogonal ray imaging is a new low-dose imaging technology under study aimed at assist externalbeam radiotherapy (EBRT) treatments. It consists in detecting radiation scattered in the patient and emitted perpendicularly to the incident beam. Such radiation can be collected by positioning a multi-sliced, collimator-based, 1D detector system parallel to the beam axis, hence collecting such orthogonal rays, or by using a pinhole-like detector system positioned above or below the patient. This system can potentially be useful for on-board imaging, or real-time EBRT monitoring. In terms of prostate cancer irradiation, the use of implanted fiducial markers allows a more precise verification of the gland position relative to the bony anatomy. The prostate target normally exhibits intra-and interfraction motion induced by the daily variation in rectal and bladder filling. In order to solve this issue, three gold fiducial markers are inserted into the prostate. In the present study, the imaging capability provided by utilizing X-rays escaping the patient/fiducial markers orthogonally in respect to the incoming beam direction is studied by GEANT4 simulation. The results allow concluding that the signal provided by such X-rays is highly coincident with the position of the gold fiducial markers, even in situations where these have been deviated by as little as 3.0 mm.  Index Terms-image-guided radiotherapy, OrthoCT, Monte Carlo simulation, gold fiducial markers, prostate cancer

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Functional magnetic resonance imaging (fMRI) has been extensively used as a tool to map the brain processes related to somatosensory stimulation. This mapping includes the localization of task-related brain activation and the characterization of brain activity dynamics and neural circuitries related to the processing of somatosensory information. However, the magnetic resonance (MR) environment presents unique challenges regarding participant and equipment safety and compatibility. This study aims to systematically review and analyze the state-of-the-art methodologies to assess the safety and compatibility of somatosensory stimulation devices in the MR environment. A literature search, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines, was performed in PubMed, Scopus, and Web of Science to find original research on the development and testing of devices for somatosensory stimulation in the MR environment. Nineteen records that complied with the inclusion and eligibility criteria were considered. The findings are discussed in the context of the existing international standards available for the safety and compatibility assessment of devices intended to be used in the MR environment. In sum, the results provided evidence for a lack of uniformity in the applied testing methodologies, as well as an in-depth presentation of the testing methodologies and results. Lastly, we suggest an assessment methodology (safety, compatibility, performance, and user acceptability) that can be applied to devices intended to be used in the MR environment.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/, identifier CRD42021257838.

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