Outcomes of Nonoperative Management of Penetrating Abdominal Trauma Injury: A Retrospective Study.

BACKGROUND: The treatment of penetrating abdominal injuries has changed in recent years with more focus on "nonoperative management" (NOM) to avoid unnecessary laparotomies while identifying injuries early. Although the NOM approach is widely used for stab wounds, its effectiveness in managing abdominal gunshot wounds is controversial. NOM of penetrating abdominal injuries is becoming more dependent on hemodynamic stability and improved noninvasive radiological interventions. The role of NOM is significantly underreported and underestimated in developing countries, particularly in fragile and conflict-affected states such as Yemen. The present study aims to evaluate the clinical outcomes of NOM in penetrating abdominal trauma injury patients and identify factors associated with NOM failure in a low-resource setting. METHODS: A retrospective study from January 2021 to December 2022 including patients diagnosed with penetrating abdominal trauma at the General Military Hospital, Sana'a, Yemen, was conducted. Hemodynamically stable patients without peritonitis or clear indications for immediate laparotomy were candidates for NOM and were included in the study. Patients with blunt abdominal injuries, penetrating wounds outside the abdomen, particularly head injury, eviscerated structures, and gastrointestinal hemorrhage, or those pronounced dead on arrival were excluded. The primary outcome was the success and failure rate of NOM necessitating laparotomy. The secondary outcome was the factors associated with NOM failure. RESULTS: During the study, 256 patients with penetrating abdominal injury were admitted, with 222 (86.7%) undergoing immediate laparotomy and 34 (13.3%) treated with NOM. The mean age was 27.6±7.4 years. Bump explosions, mostly sharp objects (secondary blast injuries), were the main causes of injury (n=18, 52.9%). Other causes were low-velocity gunshot wounds, stab wound injuries, and shotgun injuries in 14 (41.2%), one (2.9%), and one (2.9%), respectively. The majority of patients (n=25, 55.9%) were admitted within 6-24 hours of the incident. The abdominal computed tomography (CT) scan revealed various injuries in all patients, including hemoperitoneum in 11 (32.4%), pneumoperitoneum in five (14.7%), liver injury in 15 (44.1%), foreign body attached to the wall colon in 23 (67.6%), kidney injury in two (5.9%), and splenic injury in one (2.9%). NOM was successful in 31 (91.2%) patients. NOM failed in three (8.8%). One patient was treated via the laparoscopic procedure, and two patients were treated with laparotomy procedures. Five (14.7%) cases required intensive care unit (ICU) admission, with no deaths or major complications. In univariate analysis, the presence of free intra-abdominal fluid (pneumoperitoneum) on the initial CT scan and the need for ICU admission were associated with NOM failure and were statistically significant (p<0.05). CONCLUSION: Our findings support that some penetrating abdominal trauma patients can benefit from NOM. The goal of preventing unnecessary laparotomies should be aligned with a comprehensive comprehension of the clinical signs and symptoms of NOM failure and the necessity for surgical intervention. Serial abdominal examinations remain the foundation of selected NOM; nevertheless, radiological and laboratory tests can be important tools in decision-making. In this study, free intra-abdominal fluid on the initial CT scan and the need for ICU admission were associated with NOM failure.

Major determinants of primary non function from kidney donation after Maastricht II circulatory death: A single center experience.

PURPOSE: Organ shortage greatly limits treatment of patients with end-stage chronic kidney. Maastricht type 2 donation after circulatory death (DCD) has been shown to have similar results in long term outcomes in kidney transplantation, when compared with brain dead donation. Our main goal was to assess Maastricht type 2 DCD and evaluate factors that impact on early graft function. METHODS: A retrospective study was conducted in an ECMO Referral Centre. All patients who received a kidney transplant from Maastricht type 2 DCD were included in study. Early graft function and short term outcomes were assessed. RESULTS: From October 2017 to December 2022, 47 renal grafts were collected from 24 uDCD donors. Median warm ischemia time was 106 min (94-115), cannulation time was 10 min (8; 20) and duration of extracorporeal reperfusion (ANOR) was 180 min (126-214). Regarding early graft function, 25% had immediate graft function, 63.6% had delayed graft function and 11.4% had primary non-function (PNF). There was a correlation between cannulation time (p = 0.006) and ANOR with PNF (p = 0.016). CONCLUSIONS: Cannulation time and ANOR were the main factors that correlated with PNF. Better understanding of underlying mechanisms should be sought in future studies to reduce the incidence of PNF.

British Transplantation Society guidelines on abdominal organ transplantation from deceased donors after circulatory death.

The British Transplantation Society (BTS) 'Guideline on transplantation from deceased donors after circulatory death' has recently been updated and this manuscript summarises the relevant recommendations in abdominal organ transplantation from Donation after Circulatory Death (DCD) donors, encompassing the chapters on liver, kidney, pancreas and islet cell transplantation.

Ultrasound Imaging in Subjects with Sickle Cell Disease: The Saudi Arabia Experiences.

Background: Abdominal organ sonography is a crucial part of the workup for treating sickle cell disease (SCD) patients. Objective: The main objective of this study was to evaluate the abdominal organs in SCD patients using ultrasonography. Methodology: A non-interventional descriptive cross-sectional study was carried out in Asir region Saudi Arabia from April 2019 to July 2020. The study was conducted in 78 patients with sickle cell disease (SCD). Data were gathered using a data collection sheet included demographic information, clinical information including medication types, and complications linked to SCD. Furthermore, the study evaluated abdominal ultrasound findings pertaining to the liver, gall bladder, spleen, and kidneys. The data were analyzed using Statistical Package for Social Sciences (SPSS). Results: More than half of the study participants 43 (55.1%) were females. About 53.8% of the study participants received blood transfusions, and (11.5%) receive extra-vaccine. Concerning ultrasound findings, hepatomegaly was found in seventeen (21.8%), focal liver lesions in four (5.1%), gallstones in five (6.4%), splenomegaly in fifteen (19.3%), and the presence of splenic focal lesions was found in seven (9.0%). The most frequent complication associated with SCD was osteomyelitis sepsis in six cases (7.7%). The study revealed a significant correlation between the type of crisis and type of medication used and the size of the spleen (P-value <0.01), and no notable correlation was found between the types of crises and the size of the liver (P-value >0.05). Conclusion: Abdominal sonography in SCD patients revealed a wide range of alterations in the liver, gallbladder, and spleen. The most frequently observed complications in SCD were hepatomegaly, splenomegaly, localized lesions in both organs, and the presence of gallstones.

Use of Letermovir for Primary and Secondary Cytomegalovirus Prophylaxis in Abdominal Organ Transplantation: A Single Center Experience.

BACKGROUND: Cytomegalovirus (CMV) infection after abdominal organ transplantation is associated with increased morbidity and mortality. The use of valganciclovir for CMV prophylaxis is limited by drug-induced myelosuppression and potential emergence of resistance. Letermovir is approved for primary CMV prophylaxis in CMV seropositive allogeneic hematopoietic cell transplant recipients. However, it is increasingly used off-label for prophylaxis in solid organ transplant (SOT) recipients. METHODS: Based on pharmacy records, we examined retrospectively the use of letermovir for CMV prophylaxis in abdominal transplant recipients initiated on therapy at our center from January 1, 2018 through October 15, 2020. Data were summarized using descriptive statistics. RESULTS: Twelve episodes of letermovir prophylaxis occurred in ten patients. Four patients received primary and 6 patients received secondary prophylaxis during the study period, with 1 patient receiving letermovir secondary prophylaxis on 3 separate occasions. All patients receiving letermovir for primary prophylaxis had successful outcomes. However, letermovir secondary prophylaxis was unsuccessful in 5 of the 8 episodes (62.5%) due to breakthrough CMV DNAemia and/or disease. Only 1 patient discontinued therapy due to adverse effects. CONCLUSION: Although letermovir was generally well tolerated, the high rate of failure when used as secondary prophylaxis was noteworthy. Additional controlled clinical trials assessing the safety and efficacy of letermovir prophylaxis in SOT recipients are warranted.

Impact of COVID-19 on abdominal organ transplantation: A bibliometric analysis.

BACKGROUND: Abdominal solid organ transplant (SOT) programs have been hit hard by the COVID-19 pandemic, which was officially declared as such on March 11, 2020. Over two years, the tightening and softening of limitations in response to the "waves" of infection and COVID-19 fluctuations have provided distinct issues for waitlisted patients, transplant recipients, and transplant organizations. METHOD: We searched Scopus using the terms "transplant" and "transplantation," and organ-related phrases like "intestin*," "liver," "kidney," "hepatic," "renal," and "pancrea*," as well as COVID-19 terms such as "COVID-19," "coronavirus," and "SARS-CoV-2." We included articles, reviews, conference papers, letters, notes, editorials, brief surveys, book chapters, and errata and studied nations, institutions, authors, journals, keywords, and articles. VOSviewer 1.6.18 and Excel were used to create tables and figures. RESULTS: We included 1,251 of 1,256 studies. Among them, 289 (23.1%), 489 (39.1%), and 473 (37.8%) papers were published in 2020, 2021, and 2022, with mean (SD) citations of 30.3 (53.3), 14.3 (26.8), and 4.79 (6.38), respectively. Compared to other abdominal organs, the field of kidney transplants had the highest number of articles describing the impact of COVID-19. The United States contributed the most articles, and the American Journal of Transplantation published the most articles. CONCLUSION: To our knowledge, this is the first bibliometric investigation of the impact of COVID-19 on SOT. This report provides an overview of the research conducted on SOT and COVID-19. There is potential for this bibliometric analysis to serve as a beneficial and practical resource for ongoing and future research.

Surgery for Diaphragmatic Hernia Repair: A Longitudinal Single-Institutional Experience.

Background: This study analyzed and described the clinical characteristics and surgical outcomes of diaphragmatic hernia (DH) repair according to the operative approach. Methods: After excluding cases with a combined approach and hiatal hernias, we analyzed 26 patients who underwent DH repair between 1994 and 2018. The baseline and perioperative characteristics of the thoracic approach group and the abdominal approach group were described and analyzed. Results: Fifteen of the 26 patients were treated through the thoracic approach, including 5 patients who underwent video-assisted thoracic surgery (VATS). Eleven patients underwent the abdominal approach. The thoracic approach was associated with a longer duration of DH than the abdominal approach (2 vs. 0.1 months), herniation of the right-sided abdominal organs, and herniation of the retroperitoneal organs. During the median follow-up of 23 months, there was no recurrence of DH. Conclusion: The surgical approach should be chosen considering the duration of DH and the location of herniated organs. VATS might be a safe and feasible option for repairing DH.

The effect of erect abdomen radiography on absorbed doses to internal organs and tissues: A clinical study.

BACKGROUND: As low as reasonably achievable principles (ALARA) should be applied during all X-ray examinations. In some institutions, an acute abdomen series includes both erect and supine radiography. The purpose of the study was to evaluate the effect of an erect position on absorbed dose to internal abdominal organs when compared with the supine position. MATERIAL AND METHODS: A prospective study was undertaken where 81 patients were imaged in both supine and erect positions. The PCXMC Monte Carlo software was used to estimate individual organ doses using dose area product (DAP). Absorbed doses were calculated for the large intestines, active bone marrow, liver, lungs, small intestine, stomach, gallbladder, breasts, uterus, ovaries, urinary bladder, kidneys, testicles, and prostate. RESULTS: The results showed a significant increase of absorbed dose by 1.4% when moving from a supine to an erect position. The testes were found to be the organs most affected by the erect position and then the urinary bladder. CONCLUSIONS: According to the study's findings, using the erect position during abdominal radiography increases the radiation dose for all of the selected organs compared to using a supine position. Therefore, it is advised that the use of erect abdomen radiography be restricted to certain circumstances.

Motion-robust, multi-slice, real-time MR thermometry for MR-guided thermal therapy in abdominal organs.

PURPOSE: To develop an effective and practical reconstruction pipeline to achieve motion-robust, multi-slice, real-time MR thermometry for monitoring thermal therapy in abdominal organs. METHODS: The application includes a fast spiral magnetic resonance imaging (MRI) pulse sequence and a real-time reconstruction pipeline based on multi-baseline proton resonance frequency shift (PRFS) method with visualization of temperature imaging. The pipeline supports multi-slice acquisition with minimal reconstruction lag. Simulations with a virtual motion phantom were performed to investigate the influence of the number of baselines and respiratory rate on the accuracy of temperature measurement. Phantom experiments with ultrasound heating were performed using a custom-made motion phantom to evaluate the performance of the pipeline. Lastly, experiments in healthy volunteers (N = 2) without heating were performed to evaluate the accuracy and stability of MR thermometry in abdominal organs (liver and kidney). RESULTS: The multi-baseline approach with greater than 25 baselines resulted in minimal temperature errors in the simulation. Phantom experiments demonstrated a 713 ms update time for 3-slice acquisitions. Temperature maps with 30 baselines showed clear temperature distributions caused by ultrasound heating in the respiratory phantom. Finally, the pipeline was evaluated with physiologic motions in healthy volunteers without heating, which demonstrated the accuracy (root mean square error [RMSE]) of 1.23 ± 0.18 °C (liver) and 1.21 ± 0.17 °C (kidney) and precision of 1.13 ± 0.11 °C (liver) and 1.16 ± 0.15 °C (kidney) using 32 baselines. CONCLUSIONS: The proposed real-time acquisition and reconstruction pipeline allows motion-robust, multi-slice, real-time temperature monitoring within the abdomen during free breathing.

WORD: A large scale dataset, benchmark and clinical applicable study for abdominal organ segmentation from CT image.

Whole abdominal organ segmentation is important in diagnosing abdomen lesions, radiotherapy, and follow-up. However, oncologists' delineating all abdominal organs from 3D volumes is time-consuming and very expensive. Deep learning-based medical image segmentation has shown the potential to reduce manual delineation efforts, but it still requires a large-scale fine annotated dataset for training, and there is a lack of large-scale datasets covering the whole abdomen region with accurate and detailed annotations for the whole abdominal organ segmentation. In this work, we establish a new large-scale Whole abdominal ORgan Dataset (WORD) for algorithm research and clinical application development. This dataset contains 150 abdominal CT volumes (30495 slices). Each volume has 16 organs with fine pixel-level annotations and scribble-based sparse annotations, which may be the largest dataset with whole abdominal organ annotation. Several state-of-the-art segmentation methods are evaluated on this dataset. And we also invited three experienced oncologists to revise the model predictions to measure the gap between the deep learning method and oncologists. Afterwards, we investigate the inference-efficient learning on the WORD, as the high-resolution image requires large GPU memory and a long inference time in the test stage. We further evaluate the scribble-based annotation-efficient learning on this dataset, as the pixel-wise manual annotation is time-consuming and expensive. The work provided a new benchmark for the abdominal multi-organ segmentation task, and these experiments can serve as the baseline for future research and clinical application development.

Fast and Low-GPU-memory abdomen CT organ segmentation: The FLARE challenge.

Automatic segmentation of abdominal organs in CT scans plays an important role in clinical practice. However, most existing benchmarks and datasets only focus on segmentation accuracy, while the model efficiency and its accuracy on the testing cases from different medical centers have not been evaluated. To comprehensively benchmark abdominal organ segmentation methods, we organized the first Fast and Low GPU memory Abdominal oRgan sEgmentation (FLARE) challenge, where the segmentation methods were encouraged to achieve high accuracy on the testing cases from different medical centers, fast inference speed, and low GPU memory consumption, simultaneously. The winning method surpassed the existing state-of-the-art method, achieving a 19× faster inference speed and reducing the GPU memory consumption by 60% with comparable accuracy. We provide a summary of the top methods, make their code and Docker containers publicly available, and give practical suggestions on building accurate and efficient abdominal organ segmentation models. The FLARE challenge remains open for future submissions through a live platform for benchmarking further methodology developments at https://flare.grand-challenge.org/.

Impact of the initial site of metastases on post-recurrence survival for neuroendocrine cervical cancer.

OBJECTIVE: To summarize the risk factors and emphasize the prognostic importance of the site of recurrent neuroendocrine cervical cancer (NECC). METHODS: We enrolled 88 patients who developed recurrence after radical surgery for pathological stage I-IVa primary NECC between January 2003 and 30 December 2020 and classified these cases into 7 groups based on the initial recurrence. The risk factors for post-recurrence survival (PRS) were analyzed by Kaplan-Meier and Cox regression methods. RESULTS: Among 88 NECC patients, nearly all patients (95.50%) experienced progression within 3 years. The time to progression was significantly longer in patients with lung recurrence than in patients without lung recurrence (p = 0.008). After the first recurrence, the median follow-up was 11.1 months (range 2.37-65.50 months), and the 5-year PRS was only 20.6%. The depth of invasion in the primary surgery, number of recurrent sites, abdominal organ recurrence were correlated with PRS by univariate analysis. Multivariate analyses revealed that the number of recurrent sites (p = 0.025) and abdominal organ recurrence (p = 0.031) were independent prognostic factors. Notably, the combination of immune checkpoint inhibitors and chemotherapy, with or without surgery, showed a 43.8% objective response rate in recurrent NECC. CONCLUSION: Patients with abdominal organ recurrence need more sophisticated therapy. The combination of immune therapy and chemotherapy might be an opportunity for recurrent NECC.

[Reproducibility Analysis of Iodine Concentrations of Abdominal Parenchymal Organs Based on Spectral CT].

Objective To investigate the intra-and inter-observer reproducibility of iodine concentrations of abdominal parenchymal organs based on spectral CT.Methods The water-free iodine images of the venous phase were retrospectively obtained from 50 patients with abdominal dynamic spectral CT scans.The iodine concentrations were measured in the left,right and caudate lobes of liver,spleen,pancreas and bilateral kidneys.Intraclass correlation coefficient(ICC)and Bland-Altman plot were employed to analyze the intra-and inter-observer reproducibility.Results The intra-observer ICCs of the left,right and caudate lobes of liver,spleen,pancreas,and left and right kidneys were 0.938(0.894,0.965),0.932(0.884,0.961),0.939(0.895,0.965),0.947(0.909,0.970),0.912(0.851,0.949),0.946(0.906,0.969)and 0.907(0.842,0.946),which indicated good intra-observer reproducibility.The inter-observer ICCs of the left,right and caudate lobes of liver,spleen,pancreas,and left and right kidneys were 0.947(0.909,0.970),0.927(0.875,0.958),0.943(0.902,0.968),0.956(0.924,0.975),0.934(0.887,0.962),0.927(0.875,0.958)and 0.892(0.818,0.937),which indicated good inter-observer reproducibility.Bland-Altman plots presented that more than 95% points of the intra-observer differences located within 95% CI of limits of agreement for the caudate lobe of liver,spleen,pancreas and bilateral kidneys,which was same as inter-observer differences of the caudate lobe of liver,spleen and right kidney.Conclusion The iodine concentration measurement based on the spectral CT presented good intra-and inter-observer reproducibility for the caudate lobe of liver and spleen.

High-resolution 3D abdominal segmentation with random patch network fusion.

Deep learning for three dimensional (3D) abdominal organ segmentation on high-resolution computed tomography (CT) is a challenging topic, in part due to the limited memory provide by graphics processing units (GPU) and large number of parameters and in 3D fully convolutional networks (FCN). Two prevalent strategies, lower resolution with wider field of view and higher resolution with limited field of view, have been explored but have been presented with varying degrees of success. In this paper, we propose a novel patch-based network with random spatial initialization and statistical fusion on overlapping regions of interest (ROIs). We evaluate the proposed approach using three datasets consisting of 260 subjects with varying numbers of manual labels. Compared with the canonical "coarse-to-fine" baseline methods, the proposed method increases the performance on multi-organ segmentation from 0.799 to 0.856 in terms of mean DSC score (p-value < 0.01 with paired t-test). The effect of different numbers of patches is evaluated by increasing the depth of coverage (expected number of patches evaluated per voxel). In addition, our method outperforms other state-of-the-art methods in abdominal organ segmentation. In conclusion, the approach provides a memory-conservative framework to enable 3D segmentation on high-resolution CT. The approach is compatible with many base network structures, without substantially increasing the complexity during inference. Given a CT scan with at high resolution, a low-res section (left panel) is trained with multi-channel segmentation. The low-res part contains down-sampling and normalization in order to preserve the complete spatial information. Interpolation and random patch sampling (mid panel) is employed to collect patches. The high-dimensional probability maps are acquired (right panel) from integration of all patches on field of views.

Zone-dependent acute circulatory changes in abdominal organs and extremities after resuscitative balloon occlusion of the aorta (REBOA): an experimental model.

INTRODUCTION: Resuscitative endovascular balloon occlusion of the aorta (REBOA) may be used in severely injured patients with uncontrollable bleeding. However, zone-dependent effects of REBOA are rarely described. We compared the short-term zone- and organ-specific microcirculatory changes in abdominal organs and the extremity during occlusion of the aorta in a standardized porcine model. METHODS: Male pigs were placed under general anesthesia, for median laparotomy to expose intra-abdominal organs. REBOA placement occurred in Zone 1 (from origin left subclavian artery to celiac trunk), Zone 2 (between the coeliac trunk and most caudal renal artery) and Zone 3 (distal most caudal renal artery to aortic bifurcation). Local microcirculation of the intra-abdominal organs were measured at the stomach, colon, small intestine, liver, and kidneys. Furthermore, the right medial vastus muscle was included for assessment. Microcirculation was measured using oxygen-to-see device (arbitrary units, A.U). Invasive blood pressure measurements were recorded in the carotid and femoral artery (ipsilateral). Ischemia/Reperfusion (I/R)-time was 10 min with complete occlusion. RESULTS: At baseline, microcirculation of intra-abdominal organs differed significantly (p < 0.001), the highest flow was in the kidneys (208.3 ± 32.9 A.U), followed by the colon (205.7 ± 36.2 A.U.). At occlusion in Zone 1, all truncal organs showed significant decreases (p < 0.001) in microcirculation, by 75% at the colon, and 44% at the stomach. Flow-rate changes at the extremities were non-significant (n.s). During occlusion in Zone 2, a significant decrease (p < 0.001) in microcirculation was observed at the colon (- 78%), small intestine (- 53%) and kidney (- 65%). The microcirculatory changes at the extremity were n.s. During occlusion in Zone 3, truncal and extremity microcirculatory changes were n.s. CONCLUSION: All abdominal organs showed significant changes in microcirculation during REBOA. The intra-abdominal organs react differently to the same occlusion, whereas local microcirculation in extremities appeared to be unaffected by short-time REBOA, regardless of the zone of occlusion.

Reproducibility Analysis of Iodine Concentrations of Abdominal Parenchymal Organs Based on Spectral CT / 中国医学科学院学报

Objective To investigate the intra-and inter-observer reproducibility of iodine concentrations of abdominal parenchymal organs based on spectral CT.Methods The water-free iodine images of the venous phase were retrospectively obtained from 50 patients with abdominal dynamic spectral CT scans.The iodine concentrations were measured in the left,right and caudate lobes of liver,spleen,pancreas and bilateral kidneys.Intraclass correlation coefficient(ICC)and Bland-Altman plot were employed to analyze the intra-and inter-observer reproducibility.Results The intra-observer ICCs of the left,right and caudate lobes of liver,spleen,pancreas,and left and right kidneys were 0.938(0.894,0.965),0.932(0.884,0.961),0.939(0.895,0.965),0.947(0.909,0.970),0.912(0.851,0.949),0.946(0.906,0.969)and 0.907(0.842,0.946),which indicated good intra-observer reproducibility.The inter-observer ICCs of the left,right and caudate lobes of liver,spleen,pancreas,and left and right kidneys were 0.947(0.909,0.970),0.927(0.875,0.958),0.943(0.902,0.968),0.956(0.924,0.975),0.934(0.887,0.962),0.927(0.875,0.958)and 0.892(0.818,0.937),which indicated good inter-observer reproducibility.Bland-Altman plots presented that more than 95% points of the intra-observer differences located within 95% CI of limits of agreement for the caudate lobe of liver,spleen,pancreas and bilateral kidneys,which was same as inter-observer differences of the caudate lobe of liver,spleen and right kidney.Conclusion The iodine concentration measurement based on the spectral CT presented good intra-and inter-observer reproducibility for the caudate lobe of liver and spleen.

Learning from dispersed manual annotations with an optimized data weighting policy.

Purpose: Deep learning methods have become essential tools for quantitative interpretation of medical imaging data, but training these approaches is highly sensitive to biases and class imbalance in the available data. There is an opportunity to increase the available training data by combining across different data sources (e.g., distinct public projects); however, data collected under different scopes tend to have differences in class balance, label availability, and subject demographics. Recent work has shown that importance sampling can be used to guide training selection. To date, these approaches have not considered imbalanced data sources with distinct labeling protocols. Approach: We propose a sampling policy, known as adaptive stochastic policy (ASP), inspired by reinforcement learning to adapt training based on subject, data source, and dynamic use criteria. We apply ASP in the context of multiorgan abdominal computed tomography segmentation. Training was performed with cross validation on 840 subjects from 10 data sources. External validation was performed with 20 subjects from 1 data source. Results: Four alternative strategies were evaluated with the state-of-the-art baseline as upper confident bound (UCB). ASP achieves average Dice of 0.8261 compared to 0.8135 UCB ( p < 0.01 , paired t -test) across fivefold cross validation. On withheld testing datasets, the proposed ASP achieved 0.8265 mean Dice versus 0.8077 UCB ( p < 0.01 , paired t -test). Conclusions: ASP provides a flexible reweighting technique for training deep learning models. We conclude that the proposed method adapts the sample importance, which leverages the performance on a challenging multisite, multiorgan, and multisize segmentation task.

Feasibility of real-time motion tracking using cine MRI during MR-guided radiation therapy for abdominal targets.

PURPOSE: Real-time high soft-tissue contrast magnetic resonance imaging (MRI) from the MR-Linac offers the best opportunity for accurate motion tracking during radiation therapy delivery via high-frequency two-dimensional (2D) cine imaging. This work investigates the efficacy of real-time organ motion tracking based on the registration of MRI acquired on MR-Linac. METHODS: Algorithms based on image intensity were developed to determine the three-dimensional (3D) translation of abdominal targets. 2D and 3D abdominal MRIs were acquired for 10 healthy volunteers using a high-field MR-Linac. For each volunteer, 3D respiration-gated T2 and 2D T2/T1-weighted cine in sagittal, coronal, and axial planes with a planar temporal resolution of 0.6 for 60 s was captured. Datasets were also collected on MR-compatible physical and virtual four-dimensional (4D) motion phantoms. Target contours for the liver and pancreas from the 3D T2 were populated to the cine and assumed as the ground-truth motion. We performed image registration using a research software to track the target 3D motion. Standard deviations of the error (SDE) between the ground-truth and tracking were analyzed. RESULTS: Algorithms using a research software were demonstrated to be capable of tracking arbitrary targets in the abdomen at 5 Hz with an overall accuracy of 0.6 mm in phantom studies and 2.1 mm in volunteers. However, this value is subject to patient-specific considerations, namely motion amplitude. Calculation times of < 50 ms provide a pathway of real-time motion tracking integration. A major challenge in using 2D cine MRI to track the target is handling the full 3D motion of the target. CONCLUSIONS: Feasibility to track organ motion using intensity-based registration of MRIs was demonstrated for abdominal targets. Tracking accuracy of about 2 mm was achieved for the motion of the liver and pancreatic head for typical patient motion. Further development is ongoing to improve the tracking algorithm for large and complex motions.