Simulation of Image-Guided Microwave Ablation Therapy Using a Digital Twin Computational Model.

Emerging computational tools such as healthcare digital twin modeling are enabling the creation of patient-specific surgical planning, including microwave ablation to treat primary and secondary liver cancers. Healthcare digital twins (DTs) are anatomically one-to-one biophysical models constructed from structural, functional, and biomarker-based imaging data to simulate patient-specific therapies and guide clinical decision-making. In microwave ablation (MWA), tissue-specific factors including tissue perfusion, hepatic steatosis, and fibrosis affect therapeutic extent, but current thermal dosing guidelines do not account for these parameters. This study establishes an MR imaging framework to construct three-dimensional biophysical digital twins to predict ablation delivery in livers with 5 levels of fat content in the presence of a tumor. Four microwave antenna placement strategies were considered, and simulated microwave ablations were then performed using 915 MHz and 2450 MHz antennae in Tumor Naïve DTs (control), and Tumor Informed DTs at five grades of steatosis. Across the range of fatty liver steatosis grades, fat content was found to significantly increase ablation volumes by approximately 29-l42% in the Tumor Naïve and 55-60% in the Tumor Informed DTs in 915 MHz and 2450 MHz antenna simulations. The presence of tumor did not significantly affect ablation volumes within the same steatosis grade in 915 MHz simulations, but did significantly increase ablation volumes within mild-, moderate-, and high-fat steatosis grades in 2450 MHz simulations. An analysis of signed distance to agreement for placement strategies suggests that accounting for patient-specific tumor tissue properties significantly impacts ablation forecasting for the preoperative evaluation of ablation zone coverage.

Medicolegal considerations associated with cancer during pregnancy.

The management of pregnant patients with cancer is complex and requires a multidisciplinary team to effectively diagnose, stage, and manage the cancer while also being cognizant of the potential harm that diagnosis and treatment may have on the maternal and fetal well-being. Beyond the complex clinical management of these patients is additional medicolegal consideration. Radiologists play a crucial role in the management of these patients as their knowledge of diagnostic and interventional radiology techniques allows for appropriate and safe imaging for both the mother and fetus. In addition, radiologist are able to educate patient on the different imaging modalities and techniques, thus allowing patients to make informed decisions and maintain autonomy over there care. This article will review safety considerations associated with different imaging modalities, contrast agents, interventional radiology procedures and moderate sedation related to the imaging of pregnant patient with cancer with specific attention paid to the medicolegal aspects.

Fat Quantification Imaging and Biophysical Modeling for Patient-Specific Forecasting of Microwave Ablation Therapy.

Computational tools are beginning to enable patient-specific surgical planning to localize and prescribe thermal dosing for liver cancer ablation therapy. Tissue-specific factors (e.g., tissue perfusion, material properties, disease state, etc.) have been found to affect ablative therapies, but current thermal dosing guidance practices do not account for these differences. Computational modeling of ablation procedures can integrate these sources of patient specificity to guide therapy planning and delivery. This paper establishes an imaging-data-driven framework for patient-specific biophysical modeling to predict ablation extents in livers with varying fat content in the context of microwave ablation (MWA) therapy. Patient anatomic scans were segmented to develop customized three-dimensional computational biophysical models and mDIXON fat-quantification images were acquired and analyzed to establish fat content and determine biophysical properties. Simulated patient-specific microwave ablations of tumor and healthy tissue were performed at four levels of fatty liver disease. Ablation models with greater fat content demonstrated significantly larger treatment volumes compared to livers with less severe disease states. More specifically, the results indicated an eightfold larger difference in necrotic volumes with fatty livers vs. the effects from the presence of more conductive tumor tissue. Additionally, the evolution of necrotic volume formation as a function of the thermal dose was influenced by the presence of a tumor. Fat quantification imaging showed multi-valued spatially heterogeneous distributions of fat deposition, even within their respective disease classifications (e.g., low, mild, moderate, high-fat). Altogether, the results suggest that clinical fatty liver disease levels can affect MWA, and that fat-quantitative imaging data may improve patient specificity for this treatment modality.

Online training on the safe use of fluoroscopy can result in a significant decrease in patient dose.

RATIONALE AND OBJECTIVES: Concerns over medical radiation exposure have received national press in recent years, and training in the appropriate use of radiation has become an essential component of every radiology residency program. Appropriate training is particularly important in fluoroscopy because it is commonly used by inexperienced radiology residents and has the potential to impart relatively high patient radiation doses. In an effort to minimize the radiation doses received by patients, our institution has recently initiated an online training program in the safe use of fluoroscopy. This course is required and must be completed by new radiology residents before their first fluoroscopy rotation. The goal of this study was to determine if the use of an online course in the safe use of fluoroscopy could result in decreased patient dose without affecting diagnostic quality. MATERIALS AND METHODS: Four years of retrospective procedural data for residents performing gastrointestinal and genitourinary fluoroscopic procedures without specialized training were reviewed. Incoming residents took an American Medical Association-accredited online training program in the safe use of fluoroscopy the week before their first fluoroscopy rotation. Patient dose and diagnostic quality data, inferred from the frequency of attending physician intervention necessary to complete the procedure, were collected for all exams performed by the new group of residents after completion of the training course. This was then compared to data from prior classes and stratified by procedure type. RESULTS: Statistically significant reductions in both average fluoroscopy time (FT) or dose-area-product (DAP) were found for many of the fluoroscopic procedures performed by residents who participated in the online fluoroscopy training program. Specifically, statistically significant reductions in FT for barium enema, cystogram, defecogram, and esophagram procedures (P < .001) were found. Esophagram and upper gastrointestinal studies were completed with a significantly lower DAP (P < .001). The average reduction in DAP across all procedures performed by first-year residents was 38%, whereas the average reduction in FT was 25%. Based on a review of data from all procedures performed, there was no statistically significant loss in diagnostic quality. CONCLUSION: An online training program can be effectively used to provide radiation safety instruction immediately before the start of a resident's fluoroscopy rotation, decreasing patient dose without affecting diagnostic quality.

Rab11a and its binding partners regulate the recycling of the ß1-adrenergic receptor.

ß1-adrenergic receptors (ß1-AR) are internalized in response to agonists and then recycle back for another round of signaling. The serine 312 to alanine mutant of the ß1-AR (S312A) is internalized but does not recycle. We determined that WT ß1-AR and S312A were internalized initially to an early sorting compartment because they colocalized by >70% with the early endosomal markers rab5a and early endosomal antigen-1 (EEA1). Subsequently, the WT ß1-AR trafficked via rab4a-expressing sorting endosomes to recycling endosomes. In recycling endosomes WT ß1-AR were colocalized by >70% with the rab11 GTPase. S312A did not colocalize with either rab4a or rab11, instead they exited from early endosomes to late endosomes/lysosomes in which they were degraded. Rab11a played a prominent role in recycling of the WT ß1-AR because dominant negative rab11a inhibited, while constitutively active rab11a accelerated the recycling of the ß1-AR. Next, we determined the effect of each of the rab11-interacting proteins on trafficking of the WT ß1-AR. The recycling of the ß1-AR was markedly inhibited when myosin Vb, FIP2, FIP3 and rabphillin were knocked down. These data indicate that rab11a and a select group of its binding partners play a prominent role in recycling of the human ß1-AR.