A comparison of image quality and dose delivered between two differing computed tomography (CT) imaging modalities—fan beam and cone beam—was performed. A literature review of quantitative analyses for various image quality aspects such as uniformity, signal-to-noise ratio, artifact presence, spatial resolution, modulation transfer function (MTF), and low contrast resolution was generated. With these aspects quantified, cone beam computed tomography (CBCT) shows a superior spatial resolution to that of fan beam, while fan beam shows a greater ability to produce clear and anatomically correct images with better soft tissue differentiation. The results indicate that fan beam CT produces superior images to that of on-board imaging (OBI) cone beam CT systems, while providing a considerably less dose to the patient.
Natural killer (NK) cell therapies are being increasingly used as an adoptive cell therapy for cancer because they can recognize tumor cells in an antigen-independent manner. While promising, the understanding of NK cell persistence, particularly within a harsh tumor microenvironment, is limited. Fluorine-19 ( 19 F) MRI is a noninvasive imaging modality that has shown promise in longitudinally tracking cell populations in vivo; however, it has not been studied on murine NK cells. In this study, the impact of 19 F labeling on murine NK cell viability and function was assessed in vitro and then used to quantify NK cell persistence in vivo. While there was no noticeable impact on viability, labeling NK cells with 19 F did attenuate cytotoxicity against lymphoma cells in vitro. Fluorescent microscopy verified 19 F labeling in both the cytoplasm and nucleus of NK cells. Lymphoma-bearing mice were given intratumoral injections of 19 F-labeled NK cells in which signal was detectable across the 6 day observation period via 19 F MRI. Quantification from the composite images detected 78-94% of the initially injected NK cells across 6 days, with a significant decrease between Days 3 and 6. Postmortem flow cytometry demonstrated retention of 19 F intracellularly within adoptively transferred NK cells with less than 1% of 19 F-containing cells identified as tumor-associated macrophages that presumably ingested nonviable NK cells. This work demonstrates that 19 F MRI offers a specific imaging platform to track and quantify murine NK cells within tumors noninvasively. K E Y W O R D S adoptive cell therapy (ACT), flow cytometry, fluorescence microscopy, fluorine-19 ( 19 F), in vivo imaging, MRI, natural killer cells (NKs) Abbreviations: 1 H, proton; 19 F, fluorine-19; 51 C, chromium-51; ACK, ammonium-chloride-potassium; ACT, adoptive cell transfer; bSSFP, balanced steady-state free precession; CAR, chimeric antigen receptor; CMM, complete mouse medium; CS, compressed sensing; D 2 O, deuterium oxide; ETL, echo train length; F C , cellular loading density; FOV, field of view; FSE, fast spin-echo; GFP, green fluorescent protein; GFP + , GFP positive; MFI, median fluorescent intensity; N EX , number of excitations; NK, natural killer; PET, positron emission tomography; PFC, perfluorocarbon; PFPE, perfluoropolyether; RBW, receiver bandwidth; ROI, region of interest; SPECT, single-photon emission computed tomography; SPIO, superparamagnetic iron oxide; TFA, trifluoroacetic acid; UTE, ultrashort echo time.
Many advancements taking place in the field of radiation therapy come in the form of increasingly powerful devices and specialized treatments that aim to increase precision, visualization, and facility throughput. Although these devices are very effective at their respective roles within radiotherapy, they are expensive and require specialized vaults to shield the public and the radiation worker from the ionizing radiation. A proposed device, known as the Simple XRT, is designed to circumvent the inherent drawbacks of the current devices. The Simple XRT uses a 6 MV linear accelerator that utilizes diagnostic quality computed tomography (CT) image guidance. Simple XRT will serve as a cost-effective device for treating most cancer indications.
The focus of this work is on the optimization of fluorine-19 enabled SPGR, bSSFP, and phase cycled bSSFP (bSSFP-C) pulse sequence parameters to improve signal acquisition efficiency for perfluoropolyether (PFPE) at 3T with a multi-channel coil. Bloch simulations and subsequent experimental validation were performed to determine the parameters to maximize the SNR-efficiency for each sequence. Acquisitions of the optimized SPGR, bSSFP, and bSSFP-C were then assessed for their achieved SNR-efficiency. bSSFP and bSSFP-C demonstrated increased sensitivity compared to SPGR. Feasibility of bSSFP-C with parallel imaging demonstrated the ability to reduce scan times by 2-fold without compromising the qualitative image quality.
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