26 research outputs found
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Restriction Spectrum Imaging Differentiates True Tumor Progression From Immune-Mediated Pseudoprogression: Case Report of a Patient With Glioblastoma.
Immunotherapy is increasingly used in the treatment of glioblastoma (GBM), with immune checkpoint therapy gaining in popularity given favorable outcomes achieved for other tumors. However, immune-mediated (IM)-pseudoprogression is common, remains poorly characterized, and renders conventional imaging of little utility when evaluating for treatment response. We present the case of a 64-year-old man with GBM who developed pathologically proven IM-pseudoprogression after initiation of a checkpoint inhibitor, and who subsequently developed true tumor progression at a distant location. Based on both qualitative and quantitative analysis, we demonstrate that an advanced diffusion-weighted imaging (DWI) technique called restriction spectrum imaging (RSI) can differentiate IM-pseudoprogression from true progression even when conventional imaging, including standard DWI/apparent diffusion coefficient (ADC), is not informative. These data complement existing literature supporting the ability of RSI to estimate tumor cellularity, which may help to resolve complex diagnostic challenges such as the identification of IM-pseudoprogression
Clinical applications of magnetic resonance imaging based functional and structural connectivity
Advances in computational neuroimaging techniques have expanded the armamentarium of imaging tools available for clinical applications in clinical neuroscience. Non-invasive, in vivo brain MRI structural and functional network mapping has been used to identify therapeutic targets, define eloquent brain regions to preserve, and gain insight into pathological processes and treatments as well as prognostic biomarkers. These tools have the real potential to inform patient-specific treatment strategies. Nevertheless, a realistic appraisal of clinical utility is needed that balances the growing excitement and interest in the field with important limitations associated with these techniques. Quality of the raw data, minutiae of the processing methodology, and the statistical models applied can all impact on the results and their interpretation. A lack of standardization in data acquisition and processing has also resulted in issues with reproducibility. This limitation has had a direct impact on the reliability of these tools and ultimately, confidence in their clinical use. Advances in MRI technology and computational power as well as automation and standardization of processing methods, including machine learning approaches, may help address some of these issues and make these tools more reliable in clinical use. In this review, we will highlight the current clinical uses of MRI connectomics in the diagnosis and treatment of neurological disorders; balancing emerging applications and technologies with limitations of connectivity analytic approaches to present an encompassing and appropriate perspective
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Early Hemodynamic Response Assessment of Stereotactic Radiosurgery for a Cerebral Arteriovenous Malformation Using 4D Flow MRI.
Brain AVMs treated with stereotactic radiosurgery typically demonstrate a minimum latency period of 1-3 years between treatment and nidus obliteration. Assessment of treatment response is usually limited to evaluation of AVM nidus structural changes using conventional MR imaging and MRA techniques. This report describes the use of 4D Flow MRI to also measure radiation-induced hemodynamic changes in a Spetzler-Martin grade III AVM, which were detectable as early as 6 months after treatment
Early Hemodynamic Response Assessment of Stereotactic Radiosurgery for a Cerebral Arteriovenous Malformation Using 4D Flow MRI
Brain AVMs treated with stereotactic radiosurgery typically demonstrate a minimum latency period of 1-3 years between treatment and nidus obliteration. Assessment of treatment response is usually limited to evaluation of AVM nidus structural changes using conventional MR imaging and MRA techniques. This report describes the use of 4D Flow MRI to also measure radiation-induced hemodynamic changes in a Spetzler-Martin grade III AVM, which were detectable as early as 6 months after treatment
The IMPACT of Molecular Grading of Gliomas on Contemporary Clinical Practice
More recently, significant advances have been made in the understanding of the molecular pathogenesis of gliomas. For example, isocitrate dehydrogenase (IDH) mutation is a defining event in glioma development, appearing early in gliomagenesis and giving rise to gliomas with distinct behavior. Mutations in IDH, a rate-limiting enzyme in the Krebs cycle, likely affect metabolic activity and genetic expression
Adverse Events Involving Radiation Oncology Medical Devices: Comprehensive Analysis of US Food and Drug Administration Data, 1991 to 2015.
PurposeRadiation oncology relies on rapidly evolving technology and highly complex processes. The US Food and Drug Administration collects reports of adverse events related to medical devices. We sought to characterize all events involving radiation oncology devices (RODs) from the US Food and Drug Administration's postmarket surveillance Manufacturer and User Facility Device Experience (MAUDE) database, comparing these with non-radiation oncology devices.Methods and materialsMAUDE data on RODs from 1991 to 2015 were sorted into 4 product categories (external beam, brachytherapy, planning systems, and simulation systems) and 5 device problem categories (software, mechanical, electrical, user error, and dose delivery impact). Outcomes included whether the device was evaluated by the manufacturer, adverse event type, remedial action, problem code, device age, and time since 510(k) approval. Descriptive statistics were performed with linear regression of time-series data. Results for RODs were compared with those for other devices by the Pearson χ2 test for categorical data and 2-sample Kolmogorov-Smirnov test for distributions.ResultsThere were 4234 ROD and 4,985,698 other device adverse event reports. Adverse event reports increased over time, and events involving RODs peaked in 2011. Most ROD reports involved external beam therapy (50.8%), followed by brachytherapy (24.9%) and treatment planning systems (21.6%). The top problem types were software (30.4%), mechanical (20.9%), and user error (20.4%). RODs differed significantly from other devices in each outcome (P<.001). RODs were more likely to be evaluated by the manufacturer after an event (46.9% vs 33.0%) but less likely to be recalled (10.5% vs 37.9%) (P<.001). Device age and time since 510(k) approval were shorter among RODs (P<.001).ConclusionsCompared with other devices, RODs may experience adverse events sooner after manufacture and market approval. Close postmarket surveillance, improved software design, and manufacturer-user training may help mitigate these events
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Distortion Inherent to Magnetic Resonance Imaging (MRI) Can Lead to Geometric Miss in Radiosurgery Planning
PurposeAnatomic distortion is present in all magnetic resonance imaging (MRI) data because of nonlinearity of gradient fields; it measures up to several millimeters. We evaluated the potential for uncorrected MRI to lead to geometric miss of the target volume in stereotactic radiosurgery (SRS).Methods and materialsTwenty-eight SRS cases were studied retrospectively. MRI scans were corrected for gradient nonlinearity distortion in 3 dimensions, and gross tumor volumes (GTVs) were contoured. The manufacturer-specified distortion field was then reapplied to GTV masks to allow measurement of GTV displacement in uncorrected images. The uncorrected GTV was used for SRS planning, and the dose received by the true (corrected) GTV was measured.ResultsMedian displacement of the GTV resulting from gradient distortion was 1.2 mm (interquartile range, 0.1-2.3 mm), with a minimum of 0 mm and a maximum of 3.9 mm. Eight of the 28 cases met a priori criteria for "geometric miss."ConclusionsAlthough MRI distortion is often subtle on visual inspection, there is a significant clinical impact of this distortion on SRS planning. Distortion-corrected MRI should uniformly be used for intracranial radiosurgery planning because uncorrected MRI can lead to potential geometric miss
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Restriction Spectrum Imaging Differentiates True Tumor Progression From Immune-Mediated Pseudoprogression: Case Report of a Patient With Glioblastoma.
Immunotherapy is increasingly used in the treatment of glioblastoma (GBM), with immune checkpoint therapy gaining in popularity given favorable outcomes achieved for other tumors. However, immune-mediated (IM)-pseudoprogression is common, remains poorly characterized, and renders conventional imaging of little utility when evaluating for treatment response. We present the case of a 64-year-old man with GBM who developed pathologically proven IM-pseudoprogression after initiation of a checkpoint inhibitor, and who subsequently developed true tumor progression at a distant location. Based on both qualitative and quantitative analysis, we demonstrate that an advanced diffusion-weighted imaging (DWI) technique called restriction spectrum imaging (RSI) can differentiate IM-pseudoprogression from true progression even when conventional imaging, including standard DWI/apparent diffusion coefficient (ADC), is not informative. These data complement existing literature supporting the ability of RSI to estimate tumor cellularity, which may help to resolve complex diagnostic challenges such as the identification of IM-pseudoprogression
Medical Device Recalls in Radiation Oncology: Analysis of US Food and Drug Administration Data, 2002-2015
PurposeTo analyze all recalls involving radiation oncology devices (RODs) from the US Food and Drug Administration (FDA)'s recall database, comparing these with non-radiation oncology device recalls to identify discipline-specific trends that may inform improvements in device safety.Methods and materialsRecall data on RODs from 2002 to 2015 were sorted into 4 product categories (external beam, brachytherapy, planning systems, and simulation systems). Outcomes included determined cause of recall, recall class (severity), quantity in commerce, time until recall termination (date FDA determines recall is complete), and time since 510(k) approval. Descriptive statistics were performed with linear regression of time-series data. Results for RODs were compared with those for other devices by Pearson χ2 test for categorical data and 2-sample Kolmogorov-Smirnov test for distributions.ResultsThere were 502 ROD recalls and 9534 other class II device recalls during 2002 to 2015. Most recalls were for external beam devices (66.7%) and planning systems (22.9%), and recall events peaked in 2011. Radiation oncology devices differed significantly from other devices in all recall outcomes (P≤.04). Recall cause was commonly software related (49% vs 10% for other devices). Recall severity was more often moderate among RODs (97.6% vs 87.2%) instead of severe (0.2% vs 4.4%; P<.001). Time from 510(k) market approval to recall was shorter among RODs (P<.001) and progressively shortened over time. Radiation oncology devices had fewer recalled devices in commerce than other devices (P<.001).ConclusionsCompared with other class II devices, RODs experience recalls sooner after market approval and are trending sooner still. Most of these recalls were moderate in severity, and software issues are prevalent. Comprehensive analysis of recall data can identify areas for device improvement, such as better system design among RODs