Browsing by Subject "Multimodal Imaging"
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Item Open Access A novel multi-modality imaging phantom for validating interstitial needle guidance for high dose rate gynecological brachytherapy.(Journal of applied clinical medical physics, 2023-10) Eckroate, Brett; Ayala-Peacock, Diandra; Venkataraman, Rajesh; Campelo, Sabrina; Chino, Junzo; Stephens, Sarah Jo; Kim, Yongbok; Meltsner, Sheridan; Raffi, Julie; Craciunescu, OanaPurpose
To design, manufacture, and validate a female pelvic phantom for multi-modality imaging (CT, MRI, US) to benchmark a commercial needle tracking system with application in HDR gynecological (GYN) interstitial procedures.Materials and methods
A GYN needle-tracking phantom was designed using CAD software to model an average uterus from a previous patient study, a vaginal canal from speculum dimensions, and a rectum to accommodate a transrectal ultrasound (TRUS) probe. A target volume (CTVHR ) was designed as an extension from the cervix-uterus complex. Negative space molds were created from modeled anatomy and 3D printed. Silicone was used to cast the anatomy molds. A 3D printed box was constructed to house the manufactured anatomy for structural integrity and to accommodate the insertion of a speculum, tandem, needles, and TRUS probe. The phantom was CT-imaged to identify potential imperfections that might impact US visualization. Free-hand TRUS was used to guide interstitial needles into the phantom. The commercial tracking system was used to generate a 3D US volume. After insertion, the phantom was imaged with CT and MR and the uterus and CTVHR dimensions were verified against the CAD model.Results/conclusions
The manufactured phantom allows for accurate visualization with multiple imaging modalities and is conducive to applicator and needle insertion. The phantom dimensions from the CAD model were verified with those from each imaging modality. The phantom is low cost and can be reproducibly manufactured with the 3D printing and molding processes. Our initial experiments demonstrate the ability to integrate the phantom with a commercial tracking system for future needle tracking validation studies.Item Open Access Low- and High-Frequency Repetitive Transcranial Magnetic Stimulation Effects on Resting-State Functional Connectivity Between the Postcentral Gyrus and the Insula.(Brain connectivity, 2019-05) Addicott, Merideth A; Luber, Bruce; Nguyen, Duy; Palmer, Hannah; Lisanby, Sarah H; Appelbaum, Lawrence GregoryThe insular cortex supports the conscious awareness of physical and emotional sensations, and the ability to modulate the insula could have important clinical applications in psychiatry. Repetitive transcranial magnetic stimulation (rTMS) uses transient magnetic fields to induce electrical currents in the superficial cortex. Given its deep location in the brain, the insula may not be directly stimulated by rTMS; however, rTMS may modulate the insula via its functional connections with superficial cortical regions. Furthermore, low- versus high-frequency rTMS is thought to have opposing effects on cortical excitability, and the present study investigated these effects on brain activity and functional connectivity with the insula. Separate groups of healthy participants (n = 14 per group) received low (1 Hz)- or high (10 Hz)-frequency rTMS in five daily sessions to the right postcentral gyrus, a superficial region known to be functionally connected to the insula. Resting-state functional connectivity (RSFC) was measured pre- and post-rTMS. Both 1 and 10 Hz rTMS increased RSFC between the right postcentral gyrus and the left insula. These results suggest that low- and high-frequency rTMS has similar long-term effects on brain activity and RSFC. However, given the lack of difference, we cannot exclude the possibility that these effects are simply due to a nonspecific effect. Given this limitation, these unexpected results underscore the need for acoustic- and stimulation-matched sham control conditions in rTMS research.