Kidney tumor segmentation using a 2D U-Net followed by a statistical post-processing filter

Each year, there are about 400’000 new cases of kidney cancer worldwide causing around 175’000 deaths. For clinical decision making it is important to understand the morphometry of the tumor, which involves the timeconsuming task of delineating tumor and kidney in 3D CT images. Automatic segmentation could be an important tool for clinicians and researchers to also study the correlations between tumor morphometry and clinical outcomes. We present a segmentation method which combines the popular U-Net convolutional neural network architecture with post-processing based on statistical constraints of the available training data. The full implementation, based on PyTorch, and the trained weights can be found on GitHub http://github.com/ipa/kits2019

Association Between Changes in Circulating Tumor DNA and Post-Ablation Metastases in Colorectal Cancer & Liver Tumors

https://openworks.mdanderson.org/sumexp23/1082/thumbnail.jp

Thermal ablation with configurable shapes: a comprehensive, automated model for bespoke tumor treatment.

BACKGROUND Malignant tumors routinely present with irregular shapes and complex configurations. The lack of customization to individual tumor shapes and standardization of procedures limits the success and application of thermal ablation. METHODS We introduced an automated treatment model consisting of (i) trajectory and ablation profile planning, (ii) ablation probe insertion, (iii) dynamic energy delivery (including robotically driven control of the energy source power and location over time, according to a treatment plan bespoke to the tumor shape), and (iv) quantitative ablation margin verification. We used a microwave ablation system and a liver phantom (acrylamide polymer with a thermochromic ink) to mimic coagulation and measure the ablation volume. We estimated the ablation width as a function of power and velocity following a probabilistic model. Four representative shapes of liver tumors < 5 cm were selected from two publicly available databases. The ablated specimens were cut along the ablation probe axis and photographed. The shape of the ablated volume was extracted using a color-based segmentation method. RESULTS The uncertainty (standard deviation) of the ablation width increased with increasing power by ± 0.03 mm (95% credible interval [0.02, 0.043]) per watt increase in power and by ± 0.85 mm (95% credible interval [0, 2.5]) per mm/s increase in velocity. Continuous ablation along a straight-line trajectory resulted in elongated rotationally symmetric ablation shapes. Simultaneous regulation of the power and/or translation velocity allowed to modulate the ablation width at specific locations. CONCLUSIONS This study offers the proof-of-principle of the dynamic energy delivery system using ablation shapes from clinical cases of malignant liver tumors. RELEVANCE STATEMENT The proposed automated treatment model could favor the customization and standardization of thermal ablation for complex tumor shapes. KEY POINTS • Current thermal ablation systems are limited to ellipsoidal or spherical shapes. • Dynamic energy delivery produces elongated rotationally symmetric ablation shapes with varying widths. • For complex tumor shapes, multiple customized ablation shapes could be combined

Living Together: Conservative Protestants and Cohabitation

Recent research finds that conservative Protestants are cohabiting in no small numbers. Given the strict moral orientation of conservative Protestants, that outcome appears paradoxical. This thesis explains that paradox through the culture in action models of Swidler (1986), given the social and economic location of conservative Protestants. The thesis employs pooled General Social Survey data from 1993 to 2008 in which a question is asked that indicates cohabitation. The thesis finds that the social and economic location of conservative Protestants is related to their cohabiting. Though conservative Protestant cohabitors have lessened religiosity, much of the decline in religiosity compared to married conservative Protestants is due to the factors leading to cohabitation. But views and practices on premarital sex are the greatest factor in reducing that difference. The evidence in this thesis lends support to Swidler’s models of settled and unsettled lives in explaining cohabitation among conservative Protestants

Stereotactic Image-Guidance for Ablation of Malignant Liver Tumors

Stereotactic percutaneous ablation is a rapidly advancing modality for treatment of tumors in soft solid organs such as the liver. Each year, there are about 850,000 cases of primary liver cancer worldwide. Although surgical resection still is the gold standard for most cases, only 20–30% of patients are candidates for it, due to the advanced stage of the disease. Surgery can also be a huge burden to the patient and his/her quality of life might be temporarily severely reduced due to long hospital stays, complications, and slow recovery. To overcome these disadvantages, thermo-ablation of tumors of up to 3 cm has become a more viable alternative especially in the last decade, offering a potentially equally effective but minimally invasive and tissue sparing treatment alternative. In conjunction with improved CT imaging, stereotactic image-guidance techniques and image fusion technology were introduced to increase safety, efficacy, and accuracy of this treatment. Stereotactic image-guidance leads to a simple, fast, and accurate placement of the ablation probe into the liver tumor, which is a prerequisite for a complete destruction of the tumor by ablation. More and more physicians, including surgeons, consider ablation a viable alternative to resection whenever feasible. Patients undergoing such a minimally invasive treatment benefit from a shorter hospital stays, reduced complication rates, and faster recovery

Volumetric analyses of ablation dimensions in microwave ablation for colorectal liver metastases.

BACKGROUND In thermal ablation of malignant liver tumors, ablation dimensions remain poorly predictable. This study aimed to investigate factors influencing volumetric ablation dimensions in patients treated with stereotactic microwave ablation (SMWA) for colorectal liver metastases (CRLM). METHODS Ablation volumes from CRLM ≤3 cm treated with SMWA within a prospective European multicentre trial were segmented. Correlations between applied ablation energies and resulting effective ablation volumes (EAV) and ablation volume irregularities (AVI) were investigated. A novel measure for AVI, including minimum enclosing and maximum inscribed ellipsoid ablation volumes, and a surrogate parameter for the expansion of ablation energy (EAV per applied energy), was introduced. Potential influences of tumor and patient-specific factors on EAV per applied energy and AVI were analyzed using multivariable mixed-effects models. RESULTS A total of 116 ablations from 71 patients were included for analyses. Correlations of EAV or AVI and ablation energy were weak to moderate, with a maximum of 25% of the variability in EAV and 13% in AVI explained by the applied ablation energy. On multivariable analysis, ablation expansion (EAV per applied ablation energy) was influenced mainly by the tumor radius (B = -0.03, [CI -0.04, -0.007]). AVI was significantly larger with higher applied ablation energies (B = 0.002 [CI 0.0007, 0.002]]); liver steatosis, KRAS mutation, subcapsular location or proximity to major blood vessels had no influence. CONCLUSIONS This study confirmed that factors beyond the applied ablation energy might affect volumetric ablation dimensions, resulting in poor predictability. Further clinical trials including tissue sampling are needed to relate physical tissue properties to ablation expansion

Stereotactic and Robotic Minimally Invasive Thermal Ablation of Malignant Liver Tumors: A Systematic Review and Meta-Analysis.

Background Stereotactic navigation techniques aim to enhance treatment precision and safety in minimally invasive thermal ablation of liver tumors. We qualitatively reviewed and quantitatively summarized the available literature on procedural and clinical outcomes after stereotactic navigated ablation of malignant liver tumors. Methods A systematic literature search was performed on procedural and clinical outcomes when using stereotactic or robotic navigation for laparoscopic or percutaneous thermal ablation. The online databases Medline, Embase, and Cochrane Library were searched. Endpoints included targeting accuracy, procedural efficiency, and treatment efficacy outcomes. Meta-analysis including subgroup analyses was performed. Results Thirty-four studies (two randomized controlled trials, three prospective cohort studies, 29 case series) were qualitatively analyzed, and 22 studies were included for meta-analysis. Weighted average lateral targeting error was 3.7 mm (CI 3.2, 4.2), with all four comparative studies showing enhanced targeting accuracy compared to free-hand targeting. Weighted average overall complications, major complications, and mortality were 11.4% (6.7, 16.1), 3.4% (2.1, 5.1), and 0.8% (0.5, 1.3). Pooled estimates of primary technique efficacy were 94% (89, 97) if assessed at 1-6 weeks and 90% (87, 93) if assessed at 6-12 weeks post ablation, with remaining between-study heterogeneity. Primary technique efficacy was significantly enhanced in stereotactic vs. free-hand targeting, with odds ratio (OR) of 1.9 (1.2, 3.2) (n = 6 studies). Conclusions Advances in stereotactic navigation technologies allow highly precise and safe tumor targeting, leading to enhanced primary treatment efficacy. The use of varying definitions and terminology of safety and efficacy limits comparability among studies, highlighting the crucial need for further standardization of follow-up definitions