Multi-Frequency 3D Shear Wave Absolute Vibro-Elastography (S-WAVE) System for the Prostate.

This article describes a novel system for quantitative and volumetric measurement of tissue elasticity in the prostate using simultaneous multi-frequency tissue excitation. Elasticity is computed by using a local frequency estimator to measure the three-dimensional local wavelengths of steady-state shear waves within the prostate gland. The shear wave is created using a mechanical voice coil shaker which transmits simultaneous multi-frequency vibrations transperineally. Radio frequency data is streamed directly from a BK Medical 8848 transrectal ultrasound transducer to an external computer where tissue displacement due to the excitation is measured using a speckle tracking algorithm. Bandpass sampling is used that eliminates the need for an ultra-fast frame rate to track the tissue motion and allows for accurate reconstruction at a sampling frequency that is below the Nyquist rate. A roll motor with computer control is used to rotate the transducer and obtain 3D data. Two commercially available phantoms were used to validate both the accuracy of the elasticity measurements as well as the functional feasibility of using the system for in vivo prostate imaging. The phantom measurements were compared with 3D Magnetic Resonance Elastography (MRE), where a high correlation of 96% was achieved. In addition, the system has been used in two separate clinical studies as a method for cancer identification. Qualitative and quantitative results of 11 patients from these clinical studies are presented here. Furthermore, an AUC of 0.87±0.12 was achieved for malignant vs. benign classification using a binary support vector machine classifier trained with data from the latest clinical study with leave one patient out cross-validation.

Prevalencia y factores asociados al consumo de marihuana en universitarios de Colombia en el año 2016

Introducción: El consumo de marihuana toma un singular interés en el contexto de la universidad y en los universitarios, pues su uso podría ser parte de las relaciones sociales con sus pares. Objetivo: Describir la prevalencia y examinar los factores asociados al consumo de marihuana durante los últimos treinta días en estudiantes universitarios de Colombia durante 2016. Método: Estudio transversal analítico. Se realizó un análisis con 9555 universitarios colombianos. Fue considerado como consumidor de marihuana el universitario que manifestó haberla consumido durante los últimos treinta días. Se tomaron como variables de interés el sexo, la edad, la percepción de la situación económica, los problemas académicos y disciplinarios en la secundaria y las características de control parental. Para el análisis se reportó la prevalencia de la marihuana por cada una de las características estudiadas. Las asociaciones fueron estimadas a través de modelos lineales generalizados, tales análisis se ajustaron por el factor de expansión. Resultados: Se halló que el 9,7 % (IC 95 % 9,1 %- 10,4 %) había consumido marihuana en los últimos treinta días; los hombres (OR 2,23 IC95 % 1,92 - 2,59), aquellos que acusaron no tener control parental sobre los amigos (OR 2,32 IC95 % 1,58- 3,41) y que confesaron haber tenido problemas disciplinarios en la secundaria (OR 3,35 IC95 % 2,67-4,19), mostraron asociación con el consumo de marihuana. Conclusiones: La prevalencia de consumo de marihuana en estudiantes universitarios es elevada con respecto a otros países de la región. Destacan características como la presencia de problemas académicos o disciplinarios en la secundaria, así como un pobre control parental; ellas mostraron que tenían mayor relación con el consumo de marihuana entre los universitarios indagados.

Introduction: The consumption of marijuana takes on a singular interest in the context of the university and university students, because its use could be a part of relationships with their peers. Objective: To describe the prevalence and examine the factors associated with marijuana use during the last thirty days, in university students in Colombia, during the year 2016. Method: Cross-sectional analytical study. An analysis was carried out with 9555 Colombian university students. The university student who stated that he had used it during the last thirty (30) days was considered a marijuana user. The studied variables were sex, age, perception of the economic situation, academic and disciplinary problems in high school, and the characteristics of parental control. For analysis, the prevalence of marijuana was reported for each of the characteristics studied. The associations were estimated through generalized linear models; all analyzes were adjusted by the expansion factor. Results: It was found that 9.7% (95% CI 9.1%-10.4%) had used marijuana in the last thirty days; men (OR 2.23 CI95% 1.92 - 2.59), those who reported not having parental control over friends (OR 2.32 CI95% 1.58-3.41) and who confessed to having had disciplinary problems in high school (OR 3.35 CI95% 2.67-4.19) were associated with marijuana use. Conclusions: The prevalence of marijuana use in university students is high, compared to other countries in the region. They highlight characteristics such as the presence of academic or disciplinary problems in high school, as well as poor parental control; they showed that they had a greater relationship with the use of marijuana among the university students surveyed.

Predominio del subtipo molecular Luminal B en un grupo de mujeres con cáncer de mama infiltrante del Eje Cafetero de Colombia: Análisis por técnica de inmunohistoquímica / Predominance of the Luminal B molecular subtype in a group of women with infiltrating breast cancer from the Coffee Region of Colombia: Analysis by immunohistochemistry

Resumen El cáncer de mama es el cáncer más frecuente en las mujeres y constituye un problema de salud pública debido a sus altas tasas de morbimortalidad. El diagnóstico se hace a través de estudios rutinarios de histopatología que se complementan con estudios de expresión de receptores hormonales (Receptores de Estrógenos y Progesterona), del factor de crecimiento epidérmico humano 2 (HER2) e índice de proliferación celular (Ki67) para su subtipificación en grupos moleculares (Luminal A, Luminal B, Her2 y triple negativo), los cuales tienen implicaciones pronósticas y terapéuticas diferentes. Globalmente, se ha reportado una alta prevalencia del subtipo Luminal A, predominantemente en Norteamérica, Europa y algunos países latinoamericanos, sin embargo, los reportes en la población colombiana son heterogéneos. El objetivo de esta investigación es establecer un perfil de incidencia de dichos subtipos moleculares en una población del eje cafetero en Colombia. Retrospectivamente se analizaron muestras de 377 pacientes con diagnóstico de cáncer de mama infiltrante, entre los años 2015 a 2018. Los diagnósticos histológicos incluyeron: Carcinomas Ductal infiltrante NOS (339 casos; 89.9 %), lobulillar infiltrante (23 casos; 6.1 %), mucinoso infiltrante (6 casos; 1.5 %), papilar infiltrante (1 caso; 0.2 %) y patrones mixtos: ductal-lobulillar (3 casos; 0.7 %) y ductal con componente mucinoso (5 casos; 1.3 %), de los cuales 56.2 % (212 casos) corresponden a luminal B, 22.2 % (84 casos) a Luminal A, 14.8 % (56 casos) a triple negativo y 6.6 % (25 casos) a HER2. Estos hallazgos contrastan con la prevalencia reportada a nivel mundial. Por lo tanto, en la población del eje cafetero colombiano, se debe considerar este predominio del patrón luminal B al momento de establecer pronóstico y tratamiento por parte del personal médico tratante.

Abstract Breast cancer is the most common cancer in women and constitutes a public health problem due to its high rates of morbidity and mortality. Diagnosis is made through routine histopathology studies that are complemented by expression studies of hormone receptors (Estrogen and Progesterone Receptors), human epidermal growth factor 2 (HER2) and cell proliferation index (Ki67) for their subtyping into molecular groups (Luminal A, Luminal B, Her2 and triple negative), which have different prognostic and therapeutic implications. Globally, a high prevalence of the Luminal A subtype has been reported, predominantly in North America, Europe, and some Latin American countries; however, the reports in the Colombian population are heterogeneous. The objective of this research is to establish an incidence profile of these molecular subtypes in a population of the coffee region in Colombia. In retrospect, samples of 377 patients with a diagnosis of infiltrating breast cancer were analyzed, between the years 2015 and 2018. The histological diagnoses included: NOS infiltrating ductal carcinomas (339 cases; 89.9 %), infiltrating lobular (23 cases; 6.1%), infiltrating mucinous (6 cases; 1.5%), infiltrating papillary (1 case; 0.2%) and mixed patterns: ductal - lobular (3 cases; 0.7%) and ductal with mucinous component (5 cases; 1.3%), of which 56.2% (212 cases) correspond to luminal B, 22.2% (84 cases) to Luminal A, 14.8% (56 cases) to triple negative and 6.6% (25 cases) to HER2. These findings contrast with the prevalence reported worldwide. Therefore, in the population of the Colombian coffee region, this predominance of the luminal pattern B should be considered when establishing prognosis and treatment from medical staff.

Prevalencia y factores asociados al consumo de marihuana en adolescentes escolarizados de Colombia, en el 2016 / Prevalence and factors associated with marijuana use in school adolescents in Colombia, in 2016

Resumen Introducción: La marihuana es concebida como una droga de bajo riesgo, considerada ilegal en Colombia, si bien es la más consumida por los adolescentes. Objetivo: Describir la prevalencia y examinar los factores asociados al consumo de marihuana durante los últimos 30 días por adolescentes escolarizados de Colombia. Método: Estudio transversal analítico. Muestra constituida por 80.018 adolescentes escolarizados entre 12 y 18 años. Se considera "adolescente consumidor de marihuana", a aquél que declaró haberla consumido durante los últimos treinta días. Se tuvieron en cuenta variables de interés, el sexo, la edad, el tipo de colegio, los episodios de ideación suicida y autolesión deliberada, la existencia de problemas de rendimiento académico y disciplinarios. Se realizó una descripción de la prevalencia de marihuana por cada una de las variables de interés. Se estimaron asociaciones por medio de modelos lineales generalizados, todos los análisis fueron ajustados por el factor de expansión. Resultados: La prevalencia de consumo de marihuana en los últimos 30 días fue del 4,3 % (IC 95 % 4,1 %- 4,6 %). Las mayores prevalencias de consumo se registraron en adolescentes que habían reportado 3 o más veces de ideación suicida en los últimos 12 meses, y en aquellos que acusaron 3 o más veces de autolesión deliberada en los últimos 12 meses (10,4 % y 10,0 %, respectivamente). Se encontró una asociación con todas las variables estudiadas. Conclusiones: Se evidenció una fuerte asociación entre el consumo de marihuana y presencia de episodios de autolesiones deliberadas y episodios de ideación suicida en adolescentes escolarizados.

Summary Introduction: Marijuana is conceived as a low-risk drug, considered illegal in Colombia, and the most consumed by adolescents. Objective: To describe the prevalence and examine the factors associated with marijuana use during the last 30 days by adolescents in school in Colombia. Method: Cross-sectional analytical study. Sample is 80,018 adolescents in school between 12 and 18 years of age. An "adolescent user of marijuana" is one who declared having used it during the last thirty days. Variables of interest were considered: sex, age, type of school, episodes of suicidal ideation and deliberate self-harm, the existence of academic and disciplinary performance problems. A description of the prevalence of marijuana was made for each of the variables of interest. Associations were estimated using generalized linear models, all analyzes were adjusted for the expansion factor. Results: The prevalence of marijuana use in the last 30 days was 4.3% (95% CI 4.1%-4.6%). The highest prevalence of consumption was recorded in adolescents who had reported 3 or more times of suicidal ideation in the last 12 months, and in those who accused 3 or more times of deliberate self-harm in the last 12 months (10.4% and 10. 0%, respectively). An association was found with all the variables studied. Conclusions: A strong association was found between marijuana use and the presence of episodes of deliberate self-harm and episodes of suicidal ideation in school adolescents.

Autolesiones deliberadas y consumo de sustancias psicoactivas en adolescentes escolarizados de Colombia 2016 / Deliberate self-harm and psychoactive substance use in colombian school adolescents

BACKGROUND: Deliberate self-harm and the consumption of psy- choactive substances are important public health problems among adolescents. AIM: To determine the association of deliberate self-harm with the consumption of psychoactive substances, in school adolescents in Colombia. MATERIAL AND METHODS: A survey about deliberate self harm and psychoactive substance use during the last 12 months was answered by 80 018 adolescents aged between 12 and 18 years. RESULTS: The prevalence of deliberate self-harm in the last 12 months was 14.1%. The use of psychoactive drugs was associated with deliberate self-harm. The greatest association was observed with the use of non-prescription tranquilizers (Odds ratio 4.05 95% confidence intervals 3.42-4.81). CONCLUSIONS: We observed an association between deliberate self-harm and the consumption of different psychoactive substances.

[Deliberate self-harm and psychoactive substance use in colombian school adolescents]. / Autolesiones deliberadas y consumo de sustancias psicoactivas en adolescentes escolarizados de Colombia 2016.

BACKGROUND: Deliberate self-harm and the consumption of psy- choactive substances are important public health problems among adolescents. AIM: To determine the association of deliberate self-harm with the consumption of psychoactive substances, in school adolescents in Colombia. MATERIAL AND METHODS: A survey about deliberate self harm and psychoactive substance use during the last 12 months was answered by 80 018 adolescents aged between 12 and 18 years. RESULTS: The prevalence of deliberate self-harm in the last 12 months was 14.1%. The use of psychoactive drugs was associated with deliberate self-harm. The greatest association was observed with the use of non-prescription tranquilizers (Odds ratio 4.05 95% confidence intervals 3.42-4.81). CONCLUSIONS: We observed an association between deliberate self-harm and the consumption of different psychoactive substances.

A multiparametric volumetric quantitative ultrasound imaging technique for soft tissue characterization.

Quantitative ultrasound (QUS) offers a non-invasive and objective way to quantify tissue health. We recently presented a spatially adaptive regularization method for reconstruction of a single QUS parameter, limited to a two dimensional region. That proof-of-concept study showed that regularization using homogeneity prior improves the fundamental precision-resolution trade-off in QUS estimation. Based on the weighted regularization scheme, we now present a multiparametric 3D weighted QUS (3D QUS) method, involving the reconstruction of three QUS parameters: attenuation coefficient estimate (ACE), integrated backscatter coefficient (IBC) and effective scatterer diameter (ESD). With the phantom studies, we demonstrate that our proposed method accurately reconstructs QUS parameters, resulting in high reconstruction contrast and therefore improved diagnostic utility. Additionally, the proposed method offers the ability to analyze the spatial distribution of QUS parameters in 3D, which allows for superior tissue characterization. We apply a three-dimensional total variation regularization method for the volumetric QUS reconstruction. The 3D regularization involving N planes results in a high QUS estimation precision, with an improvement of standard deviation over the theoretical 1/N rate achievable by compounding N independent realizations. In the in vivo liver study, we demonstrate the advantage of adopting a multiparametric approach over the single parametric counterpart, where a simple quadratic discriminant classifier using feature combination of three QUS parameters was able to attain a perfect classification performance to distinguish between normal and fatty liver cases.

Three-Dimensional Multi-Frequency Shear Wave Absolute Vibro-Elastography (3D S-WAVE) With a Matrix Array Transducer: Implementation and Preliminary In Vivo Study of the Liver.

Magnetic resonance elastography (MRE) is commonly regarded as the imaging-based gold-standard for liver fibrosis staging, comparable to biopsy. While ultrasound-based elastography methods for liver fibrosis staging have been developed, they are confined to a 1D or a 2D region of interest and to a limited depth. 3D Shear Wave Absolute Vibro-Elastography (S-WAVE) is a steady-state, external excitation, volumetric elastography technique that is similar to MRE, but has the additional advantage of multi-frequency excitation. We present a novel ultrasound matrix array implementation of S-WAVE that takes advantage of 3D imaging. We use a matrix array transducer to sample axial multi-frequency steady-state tissue motion over a volume, using a Color Power Angiography sequence. Tissue motion with the frequency components {40,50,60} and {45,55,65} Hz are acquired over a (90° lateral) × (40° elevational) × (16 cm depth) sector with an acquisition time of 12 seconds. We compute the elasticity map in 3D using local spatial frequency estimation. We characterize this new approach in tissue phantoms against measurements obtained with transient elastography and MRE. Six healthy volunteers and eight patients with chronic liver disease were imaged. Their MRE and S-WAVE volumes were aligned using T1 to B-mode registration for direct comparison in common regions of interest. S-WAVE and MRE results are correlated with R2 = 0.92, while MRE and TE results are correlated with R2 = 0.71. Our findings show that S-WAVE with matrix array has the potential to deliver a similar assessment of liver fibrosis as MRE in a more accessible, inexpensive way, to a broader set of patients.

Prostate brachytherapy intraoperative dosimetry using a combination of radiographic seed localization with a C-arm and deformed ultrasound prostate contours.

PURPOSE: The purpose of the study was to assess the feasibility of performing intraoperative dosimetry for permanent prostate brachytherapy by combining transrectal ultrasound (TRUS) and fluoroscopy/cone beam CT [CBCT] images and accounting for the effect of prostate deformation. METHODS AND MATERIALS: 13 patients underwent TRUS and multiview two-dimensional fluoroscopic imaging partway through the implant, as well as repeat fluoroscopic imaging with the TRUS probe inserted and retracted, and finally three-dimensional CBCT imaging at the end of the implant. The locations of all the implanted seeds were obtained from the fluoroscopy/CBCT images and were registered to prostate contours delineated on the TRUS images based on a common subset of seeds identified on both image sets. Prostate contours were also deformed, using a finite-element model, to take into account the effect of the TRUS probe pressure. Prostate dosimetry parameters were obtained for fluoroscopic and CBCT-dosimetry approaches and compared with the standard-of-care Day-0 postimplant CT dosimetry. RESULTS: High linear correlation (R2 > 0.8) was observed in the measured values of prostate D90%, V100%, and V150%, between the two intraoperative dosimetry approaches. The prostate D90% and V100% obtained from intraoperative dosimetry methods were in agreement with the postimplant CT dosimetry. Only the prostate V150% was on average 4.1% (p-value <0.05) higher in the CBCT-dosimetry approach and 6.7% (p-value <0.05) higher in postimplant CT dosimetry compared with the fluoroscopic dosimetry approach. Deformation of the prostate by the ultrasound probe appeared to have a minimal effect on prostate dosimetry. CONCLUSIONS: The results of this study have shown that both of the proposed dosimetric evaluation approaches have potential for real-time intraoperative dosimetry.

Automatic detection of brachytherapy seeds in 3D ultrasound images using a convolutional neural network.

A novel approach for automatic localization of brachytherapy seeds in 3D transrectal ultrasound (TRUS) images, using machine learning based algorithm, is presented. 3D radiofrequency ultrasound signals were collected from 13 patients using the linear array of the TRUS probe during the brachytherapy procedure in which needles are used for insertion of stranded seeds. Gold standard for the location of seeds on TRUS data were obtained with the guidance of the complete reconstruction of the seed locations from multiple C-arm fluoroscopy views and used in the creation of the training set. We designed and trained a convolutional neural network (CNN) model that worked on 3D cubical sub-regions of the TRUS images, that will be referred to as patches, representing seed, non-seed within a needle track and non-seed elsewhere in the images. The models were trained with these patches to detect the needle track first and then the individual seeds within the needle track. A leave-one-out cross validation approach was used to test the model on the data from eight of the patients, for whom accurate seed locations were available from fluoroscopic imaging. The total inference time was about 7 min for needle track detection in each patient's image and approximately 1 min for seed detection in each needle, leading to a total seed detection time of less than 15 min. Our seed detection algorithm achieved [Formula: see text] precision, [Formula: see text] recall and [Formula: see text] F1_score. The results from our CNN-based method were compared to manual seed localization performed by an expert. The CNN model yielded higher precision (lower false discovery rate) compared to the manual method. The automated approach requires little modification to the current clinical setups and offers the prospect of application in real time intraoperative dosimetric analysis of the implant.

A partial augmented reality system with live ultrasound and registered preoperative MRI for guiding robot-assisted radical prostatectomy.

We propose an image guidance system for robot assisted laparoscopic radical prostatectomy (RALRP). A virtual 3D reconstruction of the surgery scene is displayed underneath the endoscope's feed on the surgeon's console. This scene consists of an annotated preoperative Magnetic Resonance Image (MRI) registered to intraoperative 3D Trans-rectal Ultrasound (TRUS) as well as real-time sagittal 2D TRUS images of the prostate, 3D models of the prostate, the surgical instrument and the TRUS transducer. We display these components with accurate real-time coordinates with respect to the robot system. Since the scene is rendered from the viewpoint of the endoscope, given correct parameters of the camera, an augmented scene can be overlaid on the video output. The surgeon can rotate the ultrasound transducer and determine the position of the projected axial plane in the MRI using one of the registered da Vinci instruments. This system was tested in the laboratory on custom-made agar prostate phantoms. We achieved an average total registration accuracy of 3.2 â€¯±â€¯ 1.3 mm. We also report on the successful application of this system in the operating room in 12 patients. The average registration error between the TRUS and the da Vinci system for the last 8 patients was 1.4 â€¯±â€¯ 0.3 mm and average target registration error of 2.1 â€¯±â€¯ 0.8 mm, resulting in an in vivo overall robot system to MRI mean registration error of 3.5 mm or less, which is consistent with our laboratory studies.

On the feasibility of transperineal 3D ultrasound image guidance for robotic radical prostatectomy.

PURPOSE: Prostate cancer is the most prevalent form of male-specific cancers. Robot-assisted laparoscopic radical prostatectomy (RALRP) using the da Vinci surgical robot has become the gold-standard treatment for organ-confined prostate cancer. To improve intraoperative visualization of anatomical structures, many groups have developed techniques integrating transrectal ultrasound (TRUS) into the surgical workflow. TRUS, however, is intrusive and does not provide real-time volumetric imaging. METHODS: We propose a proof-of-concept system offering an alternative noninvasive transperineal view of the prostate and surrounding structures using 3D ultrasound (US), allowing for full-volume imaging in any anatomical plane desired. The system aims to automatically track da Vinci surgical instruments and display a real-time US image registered to preoperative MRI. We evaluate the approach using a custom prostate phantom, an iU22 (Philips Healthcare, Bothell, WA) US machine with an xMATRIX X6-1 transducer, and a custom probe fixture. A novel registration method between the da Vinci kinematic frame and 3D US is presented. To evaluate the entire registration pipeline, we use a previously developed MRI to US deformable registration algorithm. RESULTS: Our US calibration technique yielded a registration error of 0.84 mm, compared to 1.76 mm with existing methods. We evaluated overall system error with a prostate phantom, achieving a target registration error of 2.55 mm. CONCLUSION: Transperineal imaging using 3D US is a promising approach for image guidance during RALRP. Preliminary results suggest this system is comparable to existing guidance systems using TRUS. With further development and testing, we believe our system has the potential to improve patient outcomes by imaging anatomical structures and prostate cancer in real time.

Real-Time FEM-Based Registration of 3-D to 2.5-D Transrectal Ultrasound Images.

We present a novel technique for real-time deformable registration of 3-D to 2.5-D transrectal ultrasound (TRUS) images for image-guided, robot-assisted laparoscopic radical prostatectomy (RALRP). For RALRP, a pre-operatively acquired 3-D TRUS image is registered to thin-volumes comprised of consecutive intra-operative 2-D TRUS images, where the optimal transformation is found using a gradient descent method based on analytical first and second order derivatives. Our method relies on an efficient algorithm for real-time extraction of arbitrary slices from a 3-D image deformed given a discrete mesh representation. We also propose and demonstrate an evaluation method that generates simulated models and images for RALRP by modeling tissue deformation through patient-specific finite-element models (FEM). We evaluated our method on in-vivo data from 11 patients collected during RALRP and focal therapy interventions. In the presence of an average landmark deformation of 3.89 and 4.62 mm, we achieved accuracies of 1.15 and 0.72 mm, respectively, on the synthetic and in-vivo data sets, with an average registration computation time of 264 ms, using MATLAB on a conventional PC. The results show that the real-time tracking of the prostate motion and deformation is feasible, enabling a real-time augmented reality-based guidance system for RALRP.].

Focal application of low-dose-rate brachytherapy for prostate cancer: a pilot study.

PURPOSE: To evaluate the feasibility and to report the early outcomes of focal treatment of prostate cancer using low-dose-rate brachytherapy (LDR-PB). MATERIAL AND METHODS: Seventeen patients were screened with multi-parametric magnetic resonance imaging (mpMRI), 14 of whom proceeded to receive trans-perineal template mapping biopsy (TTMB). Focal LDR-PB was performed on five eligible patients using dual air kerma strength treatment plans based on planning target volumes derived from cancer locations and determined by TTMB. Patient follow-up includes prostate specific antigen (PSA) measurements, urinary and sexual function questionnaires, repeated imaging and TTMB at specific intervals post-treatment. RESULTS: Feasibility of focal LDR-PB was shown and short-term outcomes are promising. While the detection rate of tumors, a majority of which were low grade GS 3 + 3, was found to be low on mpMRI (sensitivity of 37.5%), our results suggest the potential of mpMRI in detecting the presence of higher grade (GS ≥ 3 + 4), and bilateral disease indicating its usefulness as a screening tool for focal LDR-PB. CONCLUSIONS: Low-dose-rate brachytherapy is a favorable ablation option for focal treatment of prostate cancer, requiring minimal modification to the standard (whole gland) LDR-PB treatment, and appears to have a more favorable side effect profile. Further investigation, in the form of a larger study, is needed to assess the methods used and the long-term outcomes of focal LDR-PB.

Ex vivo and simulator models teaching therapeutic ERCP and EUS: description of SOBED's first course.

Teaching models in endoscopy are important tools to minimize risks derived from endoscopic procedures, taking into account that therapeutic endoscopy, also known as surgical endoscopy, has greatly developed during the last decade. This results from the fact that minimally invasive procedures present relevant contributions and promote more comfort to patients. In this context, ex vivo teaching models and virtual simulators are important tools to the safe acquisition of abilities. In this article, the Brazilian Society of Digestive Endoscopy presents and describes its first course of therapeutic ERCP and EUS in models of laboratory teaching.

Intraoperative registered transrectal ultrasound guidance for robot-assisted laparoscopic radical prostatectomy.

PURPOSE: To provide unencumbered real-time ultrasound image guidance during robot-assisted laparoscopic radical prostatectomy, we developed a robotic transrectal ultrasound system that tracks the da Vinci® Surgical System instruments. We describe our initial clinical experience with this system. MATERIALS AND METHODS: After an evaluation in a canine model, 20 patients were enrolled in the study. During each procedure the transrectal ultrasound transducer was manually positioned using a brachytherapy stabilizer to provide good imaging of the prostate. Then the transrectal ultrasound was registered to the da Vinci robot by a previously validated procedure. Finally, automatic rotation of the transrectal ultrasound was enabled such that the transrectal ultrasound imaging plane safely tracked the tip of the da Vinci instrument controlled by the surgeon, while real-time transrectal ultrasound images were relayed to the surgeon at the da Vinci console. Tracking was activated during all critical stages of the surgery. RESULTS: The transrectal ultrasound robot was easy to set up and use, adding 7 minutes (range 5 to 14) to the procedure. It did not require an assistant or additional control devices. Qualitative feedback was acquired from the surgeons, who found transrectal ultrasound useful in identifying the urethra while passing the dorsal venous complex suture, defining the prostate-bladder interface during bladder neck dissection, identifying the seminal vesicles and their location with respect to the rectal wall, and identifying the distal prostate boundary at the apex. CONCLUSIONS: Real-time, registered robotic transrectal ultrasound guidance with automatic instrument tracking during robot-assisted laparoscopic radical prostatectomy is feasible and potentially useful. The results justify further studies to establish whether the approach can improve procedure outcomes.

Multi-parametric 3D quantitative ultrasound vibro-elastography imaging for detecting palpable prostate tumors.

In this article, we describe a system for detecting dominant prostate tumors, based on a combination of features extracted from a novel multi-parametric quantitative ultrasound elastography technique. The performance of the system was validated on a data-set acquired from n = 10 patients undergoing radical prostatectomy. Multi-frequency steady-state mechanical excitations were applied to each patient's prostate through the perineum and prostate tissue displacements were captured by a transrectal ultrasound system. 3D volumetric data including absolute value of tissue elasticity, strain and frequency-response were computed for each patient. Based on the combination of all extracted features, a random forest classification algorithm was used to separate cancerous regions from normal tissue, and to compute a measure of cancer probability. Registered whole mount histopathology images of the excised prostate gland were used as a ground truth of cancer distribution for classifier training. An area under receiver operating characteristic curve of 0.82 +/- 0.01 was achieved in a leave-one-patient-out cross validation. Our results show the potential of multi-parametric quantitative elastography for prostate cancer detection for the first time in a clinical setting, and justify further studies to establish whether the approach can have clinical use.

Seed localization in ultrasound and registration to C-arm fluoroscopy using matched needle tracks for prostate brachytherapy.

We propose a novel fiducial-free approach for the registration of C-arm fluoroscopy to 3-D ultrasound images of prostate brachytherapy implants to enable dosimetry. The approach involves the reliable detection of a subset of radioactive seeds from 3-D ultrasound, and the use of needle tracks in both ultrasound and fluoroscopy for registration. Seed detection in ultrasound is achieved through template matching in 3-D radio frequency ultrasound signals, followed by thresholding and spatial filtering. The resulting subset of seeds is registered to the complete reconstruction of the brachytherapy implant from multiple C-arm fluoroscopy views. To compensate for the deformation caused by the ultrasound probe, simulated warping is applied to the seed cloud from fluoroscopy. The magnitude of the applied warping is optimized within the registration process. The registration is performed in two stages. First, the needle track projections from fluoroscopy and ultrasound are matched. Only the seeds in the matched needles are then used as fiducials for point-based registration. We report results from a physical phantom with a realistic implant (average postregistration seed distance of 1.6 ± 1.2 mm) and from five clinical patient datasets (average error: 2.8 ± 1.5 mm over 128 detected seeds). We conclude that it is feasible to use RF ultrasound data, template matching, and spatial filtering to detect a reliable subset of brachytherapy seeds from ultrasound to enable registration to fluoroscopy for dosimetry.

Use of needle track detection to quantify the displacement of stranded seeds following prostate brachytherapy.

We aim to compute the movement of permanent stranded implant brachytherapy radioactive sources (seeds) in the prostate from the planned seed distribution to the intraoperative fluoroscopic distribution, and then to the postimplant computed tomography (CT) distribution. We present a novel approach to matching the seeds in these distributions to the plan by grouping the seeds into needle tracks. First, we identify the implantation axis using a sample consensus algorithm. Then, we use a network flow algorithm to group seeds into their needle tracks. Finally, we match the needles from the three stages using both their transverse plane location and the number of seeds per needle. We validated our approach on eight clinical prostate brachytherapy cases, having a total of 871 brachytherapy seeds distributed in 193 needles. For the intraoperative and postimplant data, 99.31% and 99.41% of the seeds were correctly assigned, respectively. For both the preplan to fluoroscopic and fluoroscopic to CT registrations, 100% of the needles were correctly matched. We show that there is an average intraoperative seed displacement of 4.94±2.42 mm and a further 2.97±1.81 mm of postimplant movement. This information reveals several directional trends and can be used for quality control, treatment planning, and intraoperative dosimetry that fuses ultrasound and fluoroscopy.

Intra-operative prostate brachytherapy dosimetry based on partial seed localization in ultrasound and registration to C-arm fluoroscopy.

Intraoperative dosimetry during prostate brachytherapy is a long standing clinical problem. We propose a novel framework to address this problem by reliable detection of a subset of seeds from 3D transrectal ultrasound and registration to fluoroscopy. Seed detection in ultrasound is achieved through template matching in the RF ultrasound domain followed by thresholding and spatial filtering based on the fixed distance between stranded seeds. This subset of seeds is registered to the complete reconstruction of the implant in C-arm fluoroscopy. We report results, validated with a leave-one-needle-out approach, both in a phantom (average post-registration seed distance of 2.5 mm) and in three clinical patient datasets (average error: 3.9 mm over 113 seeds).