GPU-based 3D iceball modeling for fast cryoablation simulation and planning

Purpose The elimination of abdominal tumors by percutaneous cryoablation has been shown to be an effective and less invasive alternative to open surgery. Cryoablation destroys malignant cells by freezing them with one or more cryoprobes inserted into the tumor through the skin. Alternating cycles of freezing and thawing produce an enveloping iceball that causes the tumor necrosis. Planning such a procedure is difficult and time-consuming, as it is necessary to plan the number and cryoprobe locations and predict the iceball shape which is also influenced by the presence of heating sources, e.g., major blood vessels and warm saline solution, injected to protect surrounding structures from the cold. Methods This paper describes a method for fast GPU-based iceball modeling based on the simulation of thermal propagation in the tissue. Our algorithm solves the heat equation within a cube around the cryoprobes tips and accounts for the presence of heating sources around the iceball. Results Experimental results of two studies have been obtained: an ex vivo warm gel setup and simulation on five retrospective patient cases of kidney tumors cryoablation with various levels of complexity of the vascular structure and warm saline solution around the tumor tissue. The experiments have been conducted in various conditions of cube size and algorithm implementations. Results show that it is possible to obtain an accurate result within seconds. Conclusion The promising results indicate that our method yields accurate iceball shape predictions in a short time and is suitable for surgical planning

Lithological Mapping and Identification of Argillic and Propylitic Alteration Zones at Anjerd Volcanic Terrain

Anjerd area is part of Arasbaran volcanic-magmatic terrain in northwestern Iran. The area is covered by multiple intrusive bodies of diverse compositions, volcanic, volcaniclastic, sedimentary and young alluvial deposits. The usefulness of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data for the lithologic mapping of the area and identification of alteration zones is investigated in this study. To carry out the study, one ASTER frame was atmospherically calibrated by Internal Average Relative Reflectance (IARR). The False Color Composite (FCC) and Principal Component Analysis (PCA) images were used for discriminating lithologic units along with Spectral Angle Mapper (SAM) and Matched Filtering (MF). The pure endmember image spectra were extracted from Pixel Purity (PPI) algorithm. The results showed that PCA and FCC can be used to discriminate sedimentary rocks from magmatic and volcanic rocks. Because feldspars and quartz are relatively featureless in shortwave infrared (SWIR) spectral region the methods were not capable to distinguish between various magmatic rocks except for basalts with darker color and higher pyroxene content. The MF gave better results than SAM algorithm and therefore MF is recommended over SAM for studying similar terrains. The argillic and propylitic alteration zones were detected by band ratios. The results showed that MF algorithm in combination with band ratios can be used to distinguish magmatic rocks from sedimentary rocks and delineate the alteration zone

Lithological Mapping and Identification of Argillic and Propylitic Alteration Zones at Anjerd Volcanic Terrain

Anjerd area is part of Arasbaran volcanic-magmatic terrain in northwestern Iran. The area is covered by multiple intrusive bodies of diverse compositions, volcanic, volcaniclastic, sedimentary and young alluvial deposits. The usefulness of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data for the lithologic mapping of the area and identification of alteration zones is investigated in this study. To carry out the study, one ASTER frame was atmospherically calibrated by Internal Average Relative Reflectance (IARR). The False Color Composite (FCC) and Principal Component Analysis (PCA) images were used for discriminating lithologic units along with Spectral Angle Mapper (SAM) and Matched Filtering (MF). The pure endmember image spectra were extracted from Pixel Purity (PPI) algorithm. The results showed that PCA and FCC can be used to discriminate sedimentary rocks from magmatic and volcanic rocks. Because feldspars and quartz are relatively featureless in shortwave infrared (SWIR) spectral region the methods were not capable to distinguish between various magmatic rocks except for basalts with darker color and higher pyroxene content. The MF gave better results than SAM algorithm and therefore MF is recommended over SAM for studying similar terrains. The argillic and propylitic alteration zones were detected by band ratios. The results showed that MF algorithm in combination with band ratios can be used to distinguish magmatic rocks from sedimentary rocks and delineate the alteration zone

Preclinical evaluation of the atraumatic nature of a spring loaded blunt tip coaxial needle in a swine model

International audiencePurpose: To test in vivo in an animal model the inherent atraumatic characteristics of the spring loaded blunt tip of a coaxial needle (Gangi-SoftGuard®, Apriomed, Sweden) against a conventional sharp stylet coaxial needle.Material and Methods: The study was conducted on a 40 kg male swine that was its own control for a vascular trauma model. The procedure consisted of voluntary attempts to transfix and traverse the artery/aorta under continuous real-time angiogram. Test and control needles were positioned in the region of the intercostal, superior mesenteric and femoral/deep femoral arteries, and in the aorta. Computed tomography (CT) angiogram was performed post trauma to check for bleeding in the form of extravasation of contrast material. One attempt was performed per site and needle, except for the intercostal artery where a second attempt was done with the test needle, resulting in a total of 4 and 5 tests for the control and test needles, respectively.Results: With the spring loaded blunt tip, no vascular trauma or bleeding was noted in the intercostal, superior mesenteric and femoral arteries, nor in the aorta. Vascular spasm that recovered with time was noted during the second attempt to transfix the same intercostal artery. There were consistent vascular traumas and bleedings with the control needle in all three tested arteries and the aorta, confirmed on angiogram as well as CT angiogram.Conclusion: The atraumatic feature offered by the spring loaded blunt tip prevented vascular trauma during the 5 attempts made to transfix the artery/aorta in a swin

RSNA International Trends: A Global Perspective on the COVID-19 Pandemic and Radiology in Late 2020

The COVID-19 pandemic has challenged and changed our healthcare systems around the world. There has been a heterogeneity of disease burden, healthcare resources, and non-imaging testing availability, both geographically and over time. In parallel, there has been a continued increase in understanding of how the disease affects patients, effectiveness of therapeutic options, and factors that modulate transmission risk. Here we detail experiences from radiology experts in representative countries from around the world, to share insights gained from local experience. These insights provide a guidepost to help address management challenges as cases continue to rise in many parts of the world and suggest modifications in workflow that are likely to continue after this pandemic subsides

Articulated Clinician Detection Using 3D Pictorial Structures on RGB-D Data

Reliable human pose estimation (HPE) is essential to many clinical applications, such as surgical workflow analysis, radiation safety monitoring and human-robot cooperation. Proposed methods for the operating room (OR) rely either on foreground estimation using a multi-camera system, which is a challenge in real ORs due to color similarities and frequent illumination changes, or on wearable sensors or markers, which are invasive and therefore difficult to introduce in the room. Instead, we propose a novel approach based on Pictorial Structures (PS) and on RGB-D data, which can be easily deployed in real ORs. We extend the PS framework in two ways. First, we build robust and discriminative part detectors using both color and depth images. We also present a novel descriptor for depth images, called histogram of depth differences (HDD). Second, we extend PS to 3D by proposing 3D pairwise constraints and a new method that makes exact inference tractable. Our approach is evaluated for pose estimation and clinician detection on a challenging RGB-D dataset recorded in a busy operating room during live surgeries. We conduct series of experiments to study the different part detectors in conjunction with the various 2D or 3D pairwise constraints. Our comparisons demonstrate that 3D PS with RGB-D part detectors significantly improves the results in a visually challenging operating environment.Comment: The supplementary video is available at https://youtu.be/iabbGSqRSg

Observations And Experiments For The Definition Of A New Robotic Device Dedicated To CT, CBCT And MRI-Guided Percutaneous Procedures.

In this paper, we present the work achieved to define the robotic functionalities of interest for percutaneous procedures as performed in interventional radiology. Our contributions are twofold. First, a detailed task analysis is performed with workflow analysis of biopsies, one of the most frequent tasks, under three imaging modalities, namely CT, CBCT and MRI. Second, the functionalities of a robotic assistant are identified, and we analyze whether a single device can bring an added value during procedures in the three modalities while keeping the robotized workflow close to manual tasks, to minimize learning time and difficulty of use. Experimental analysis on CBCT is notably used to confirm the interest of the determined robotic functionalities.journal articleresearch support, non-u.s. gov't2018 07importedIEEE Engineering in Medicine and Biology Society, Honolulu, United States, juillet 2018 Research team : AV