Ultrasound (US)-guided liver ablation interventions require the identification of the target lesion and the tracking of the ablation needle. However, tracking the needle is challenging because it may become invisible due to shadowing, decreasing image resolution with depth, irregular relative motion, intermittent occlusion, and a complex background with various tissue structures.In this study, we propose a MOtion-aware Ultrasound video Needle Tracking (MOUNT) model for needle tracking, focusing on the unique characteristics of the US image, the needle target, and liver tumor ablation interventions. The MOUNT model includes a module that perceives uneven motion using optical flow map, a needle tip-specific region proposal network with special attention to the tip, and a task-specific design module aggregating adjacent frames. The performance of the MOUNT model was comprehensively evaluated on 62 US videos containing 39,750 image frames obtained during liver tumor ablations. These US videos involve radiofrequency (RFA) and microwave (MWA) heating techniques, and varying levels of needle visibility. Experimental results showed that the area under the receiver operating characteristic curve (AU-ROC) for classifying whether a frame contains a needle was 0.91. The median and mean shaft direction errors were 1.6∘ and 4.2∘, respectively, while the median and mean needle tip distance errors were 3.7 mm and 6.1 mm, respectively. The state-of-the-art experimental performance indicates that the proposed MOUNT model can effectively alleviate the challenges in tracking tasks and demonstrate clinical usability. The source code is available at https://github.com/LiuNingtao/MOUNT.

Colorenal fistulae are a rare complication after percutaneous ablation of renal cell carcinoma tumors. Through-the-scope suturing (TTSS) is becoming increasingly used in the repair of gastrointestinal defects, including fistulae and perforations. We describe a technically and clinically successful case of endoscopic closure of a left-sided colorenal fistula using TTSS. TTSS is safe, relatively low cost, and easy to learn. It can be considered as an initial therapy in the closure of colonic fistulae, before proceeding to surgery, which carries significantly higher morbidity.

Purpose:Thermal ablation is a minimally invasive therapy used for the treatment of small renal cell carcinoma tumors. Treatment success is evaluated on postablation computed tomography (CT) to determine if the ablation zone covered the tumor with an adequate treatment margin (often 5 to 10 mm). Incorrect margin identification can lead to treatment misassessment, resulting in unnecessary additional ablation. Therefore, segmentation of the renal ablation zone (RAZ) is crucial for treatment evaluation. We aim to develop and assess an accurate deep learning workflow for delineating the RAZ from surrounding tissues in kidney CT images. Approach:We present an advanced deep learning method using the attention-based U-Net architecture to segment the RAZ. The workflow leverages the strengths of U-Net, enhanced with attention mechanisms, to improve the network's focus on the most relevant parts of the images, resulting in an accurate segmentation. Results:Our model was trained and evaluated on a dataset comprising 76 patients' annotated RAZs in CT images. Analysis demonstrated that the proposed workflow achieved an accuracy = 0.97 ± 0.02 , precision = 0.74 ± 0.23 , recall = 0.73 ± 0.25 , DSC = 0.70 ± 0.22 , Jaccard = 0.58 ± 0.22 , specificity = 0.99 ± 0.01 , Hausdorff distance = 6.70 ± 4.44    mm , and mean absolute boundary distance = 2.67 ± 2.22    mm . Conclusions:We used 3D CT images with RAZs and, for the first time, addressed deep-learning-based RAZ segmentation using parallel CT images. Our framework can effectively segment RAZs, allowing clinicians to automatically determine the ablation margin, making our tool ready for clinical use. Prediction time is ∼ 1    s per patient, enabling clinicians to perform quick reviews, especially in time-constrained settings.

Assessing prostate cancer (PCa) on multiparametric magnetic resonance imaging (mpMRI) has been associated with interobserver variability. Studying the search patterns of expert radiologists captured using eye tracking technology can improve lesion identification accuracy and minimize interobserver variability. However, no studies have investigated radiologist search patterns in PCa mpMRI. The objective of this pilot study was to develop a 3-dimensional (3D) mpMRI eye tracking platform and metrics to characterize radiologists’ search patterns. Four board-certified radiologists searched for PCa on mpMRI in 40 patients with known PCa while eye tracking data were collected. Quantitative metrics were developed and included characterizing physical eye movements, 3D and multiparametric search patterns, and search patterns in relation to structures. Saccade magnitudes and fixation durations varied for the different radiologists, while the relative ordering of radiologists’ saccade magnitude and fixation duration remained consistent between MR images. Among the four radiologists, one searched mpMRIs slice-by-slice (scanning), one scrolled through slices (drilling), and two used a combination. More time was spent fixating and covering the prostate defined on the T2-weighted image compared to the other images. Here, a novel platform to enable 3D mpMRI eye tracking was developed and quantitative metrics identified search pattern differences descriptive of radiologists’ PCa search patterns.

Kidney tumor ablation is a minimally invasive treatment for Renal Cell Carcinoma (RCC). Manual segmentation of the kidney ablation zone (KAZ) is time-consuming, skill-dependent, and variable, making accurate assessment of treatment efficacy challenging. We propose a deep learning-based workflow for KAZ segmentation in CT images by using residual connections, multi-scale fusion, and a proposed channel-aware block. It involved predicting on 2D slices sampled radially, followed by reconstructing and evaluating the ablated volume within the kidney. Using the segmented KAZ produced by our Channel-Aware-ResUNet++ (CAResUNet++) model, we identified the margin within the kidney, which is critical for assessing ablation success. The deep learning model was trained and evaluated on a local dataset from the academic health network (London, Canada), including annotated KAZ from 76 patients' CT images. Quantitative analysis demonstrated that the proposed pipeline achieved promising performance metrics, including 85±08% DSC, 5.21±2.94mm Hausdorff distance, and 1.82±1.01mm Mean Absolute boundary Distance (MAD) for the whole KAZ. Analysis of the predicted margin within the kidney resulted in a mean MAD and Mean Signed boundary Distance of 1.38mm and 0.52mm, respectively, indicating its robustness, reliability, and applicability in clinical settings

OBJECTIVES:Local tumour progression (LTP) after percutaneous ablation of small renal cell carcinoma (RCC) is suspected when new enhancing or enlarging soft tissue appears within the ablation zone. Benign post-treatment changes can mimic this finding. This study compares the incidence and imaging characteristics of non-malignant changes (NMC) versus LTP after renal ablation. MATERIALS AND METHODS:In this single-center, retrospective study, all patients with RCC treated with radiofrequency ablation (RFA) from February 2004 to May 2016 were identified. Post-ablation imaging reports from through May 2017 were reviewed to detect findings suspicious for LTP. Patients with suspicious findings underwent clinical, imaging, and histopathologic follow-up through May 2025 to determine the reference diagnosis. Imaging features were categorized by morphology, location within the ablation zone, and enhancement pattern. RESULTS:Among 256 patients (mean age 65.6 years ± 10.8, 193 men) with 268 treated tumours, 18 tumours (6.7%) developed suspicious imaging findings. Eight tumours (3.0%) were classified as NMC and 10 tumours (3.7%) as LTP. NMC had significantly lower CT enhancement than LTP (31 vs 152 HU, P < .001). Lesions along the renal parenchymal margin were exclusively associated with LTP (9/9), whereas abnormalities at the extrarenal margin or centrally within the ablation zone were predominantly NMC (8/9). Enhancement with washout was seen only in LTP. CONCLUSION:Non-malignant post-ablation changes can mimic LTP and occur with similar frequency. Imaging features can help differentiate benign changes from local tumour progression and reduce unnecessary re-interventions.

Liver tumour ablation procedures require accurate placement of the needle applicator at the tumour centroid. The lower-cost and real-time nature of ultrasound (US) has advantages over computed tomography for applicator guidance, however, in some patients, liver tumours may be occult on US and tumour mimics can make lesion identification challenging. Image registration techniques can aid in interpreting anatomical details and identifying tumours, but their clinical application has been hindered by the tradeoff between alignment accuracy and runtime performance, particularly when compensating for liver motion due to patient breathing or movement. Therefore, we propose a 2D-3D US registration approach to enable intra-procedural alignment that mitigates errors caused by liver motion. Specifically, our approach can correlate imbalanced 2D and 3D US image features and use continuous 6D rotation representations to enhance the model's training stability. The dataset was divided into 2388, 196, and 193 image pairs for training, validation and testing, respectively. Our approach achieved a mean Euclidean distance error of 2.28 m m ± 1.81 m m and a mean geodesic angular error of ± , with a runtime of 0.22 s per 2D-3D US image pair. These results demonstrate that our approach can achieve accurate alignment and clinically acceptable runtime, indicating potential for clinical translation.

Kidney tumor thermal ablation procedures create an ablation zone that is planned to cover the tumor and destroy malignant cells. Incorrect identification of the margins of this zone can lead to incomplete treatment, increasing the risk of recurrence, or excessive damage to healthy tissue, leading to complications such as renal dysfunction. Thus, accurate segmentation of the Kidney Ablation Zone (KAZ) is vital for assessing the treatment's efficacy and planning further interventions if necessary. Despite the significant importance of this issue, no research has been conducted yet on the segmentation of KAZ. This research proposes an advanced deep learning-based approach utilizing the Attention U-Net architecture to segment KAZ and address this problem. The proposed workflow leverages the strengths of the U-Net architecture, improved with attention mechanisms, to enhance the network's ability to focus on the most relevant regions of the images, thereby achieving appropriate segmentations. Our model was trained and evaluated on a local dataset from the London Health Sciences Centre (London, Canada) and comprised 76 patients' annotated ablation zones in kidney CT images. Quantitative analysis demonstrated that the Attention U-Net achieved promising performance metrics, including a 0.7 Dice similarity coefficient and a mean absolute boundary distance of 0.97 mm indicating its robustness and reliability in clinical settings. Furthermore, qualitative results showed that our approach effectively delineates ablation zones, providing clear and accurate boundaries critical for post-procedural assessment and planning.

Background:Retrograde transvenous obliteration is an endovascular interventional radiology procedure demonstrating safety and efficacy for secondary prophylaxis in high-risk gastric varices. However, its efficacy as primary prophylaxis is uncertain. We conducted a systematic review and case series to evaluate the utility of this technique. Methods:A literature search utilized EMBASE, MEDLINE, and the Cochrane Central Register of Controlled Trials. Inclusion criteria involved single technique obliteration, known varices, and exclusively primary prophylaxis. The primary outcome was gastric variceal bleeding, with secondary outcomes of technical success, variceal eradication, adverse events, and mortality. A retrospective case series of nine patients who underwent primary prophylaxis at our North American centre was also conducted. Results:Of the 842 articles retrieved, 69 were eligible for full-text review, with the 9 studies included in the final analysis involving balloon-occluded, but not plug-assisted or coil-assisted, techniques. Only 2/9 studies involved comparator groups, with a single prospective non-randomized trial, and there was a high risk of bias in 8/9 studies. The technical success rate of the balloon-occluded obliteration technique ranged from 82% to 100%, and the variceal eradication rate ranged from 88% to 100%. In comparative studies, patients had decreased variceal bleeding and bleeding-related mortality compared with control cohorts. Our case series demonstrated a 78% survival rate with no variceal bleeding. Post-procedure ascites and worsening esophageal varices ranged from 0-55% to 11-80%, respectively. Conclusion:This review summarizes evidence regarding the efficacy of retrograde transvenous obliteration, with available studies demonstrating a high success rate in eradicating varices and preventing bleeding-associated mortality, albeit with concerns of overall quality of existing literature.

3D ultrasound (US) imaging has shown significant benefits in enhancing the outcomes of percutaneous liver tumour ablation. Its clinical integration is crucial for transitioning 3D US into the therapeutic domain. However, challenges of tumour identification in US images continue to hinder its broader adoption. In this work, we propose a novel framework for integrating 3D US into the standard ablation workflow. We present a key component, a clinically viable 2D US–CT/MRI registration approach, leveraging 3D US as an intermediary to reduce registration complexity. To facilitate efficient verification of the registration workflow, we also propose an intuitive multimodal image visualization technique. In our study, 2D US–CT/MRI registration achieved a landmark distance error of ∼ 2–4 mm with a runtime of 0.22 s per image pair. Additionally, non-rigid registration reduced the mean alignment error by ∼ 40

The DNA Fragmentation Index (DFI) is a newer and potentially more reliable marker for male infertility, with higher values indicating poorer sperm genetic quality. This study assesses the effect of varicocele embolization on DFI in infertile men. Conducted at a single center from January 2016 to September 2021, this retrospective study involved 22 patients with a mean age of 35.2 ± 4.1 years. Post-embolization, DFI decreased from 32.3 ± 9.8% to 24.7 ± 12.9% (p=0.010), representing a 7.6% reduction. DFI analysis was performed three months post-procedure. The embolization procedure had a 100% technical success rate with no moderate or severe adverse events. Pregnancy was achieved in 55% (12/22) of patients, while three patients 14% (3/22) were lost to follow-up. There was an overall trend toward improvement in semen parameters, with sperm concentration significantly increasing (p=0.023). In conclusion, varicocele embolization significantly reduced DFI values, which is linked to improved fertility rates.

To compare and externally validate multiple proposed renal tumor ablation risk-stratification algorithms on prediction of complication and post-ablative residual disease following renal cell carcinoma (RCC) ablation with both heat and cold modalities. Retrospective study performed on 100 patients (mean age, 67.3±10.4 years) and 126 biopsy-confirmed RCC who underwent renal ablation (tumor diameter 2.5±1.0 cm; left:right kidney 56:70, T1a:T1b 121:5). Mean follow-up duration was 67.3±37.2 months. Ablative modality included 75 radiofrequency ablations (RFA), 50 cryoablations, and 1 microwave ablation (MWA). Complications were classified using the Society of Interventional Radiology adverse event classification criteria. RENAL, mRENAL, (MC)2, P-RAC, and P-RENAL were validated with area under the curve (AUC) values of ROC curves against complications and incomplete ablation. Out of 126 ablations, 11 mild (8.7%) and 2 moderate (1.6%) complications occurred. 3 of the mild complications occurred with cryoablation and 8 with RFA. Both moderate complications occurred following MWA. No severe complications were observed. T1a tumors included 10 mild complications and 2 moderate complications. T1b tumors included 1 mild complication. The most common complications were bleeding and pain. 97 ablations achieved complete ablation on first follow up, while 29 did not achieve complete ablation. Mean scores of each of the predictive algorithms are depicted in Table 227.1. Within the context of all ablative modalities, none of the algorithms were strong predictors for complications given the AUC values. When isolated to the context of cryoablations only, P-RAC (0.89), mRENAL (0.86), and RENAL (0.81) were strong predictions for complications. None of the algorithms demonstrated strong prediction for incomplete tumor ablation. Comparative evaluation suggests that the five proposed risk-scoring systems do not correlate well to either complication risk or incomplete ablation for RCC ablation with all ablative modalities; however, P-RAC, mRENAL, RENAL, and P-RENAL all achieve reasonable AUC values in the context of predicting complications using cryoablation only.

Purpose: To analyze the cost effectiveness of performing a renal mass biopsy in advance of ablation or concurrently with a percutaneous ablation procedure for the management of small renal masses (SRMs). Materials and Methods: A decision-analytic model was developed with a cohort of 65-year-old male patients with an incidental, unilateral 1-3 cm SRM. A decision tree modeled the first year of clinical intervention, after which patients entered a Markov model with a lifetime horizon. Patients were assumed to be treated in accordance with established clinical practice guidelines, including surveillance, repeat ablation for recurrence, and systemic therapy for metastasis. Healthcare cost and utility values were determined from published literature or local hospital estimates, discounted at 1.5%. Total lifetime costs were calculated from the perspective of a Canadian healthcare payer and converted to 2022 Canadian dollars (C$). The primary outcome was incremental cost-effectiveness ratio (ICER) at a willingness-to-pay threshold of C$50,000 per qualityadjusted life year (QALY) gained. The secondary outcome was ICER at a willingness-to-pay threshold of C$50,000 per life Results: Concurrent biopsy and ablation resulted in a gain of 16.4 quality-adjusted days, at an incremental cost of $386, with an ICER of C$8,494/QALY. The concurrent strategy was the dominant strategy for a prevalence of benign mass of <5%. Sequential biopsy and ablation was only cost-effective when LYs were not quality-adjusted and ablation cost was >C$4,300 or benign mass prevalence was >28% Conclusions: Concurrent biopsy and ablation is cost-effective relative to pretreatment diagnostic biopsy for management of incidental SRMs.

BACKGROUND. Observation periods after renal mass biopsy (RMB) range from 1 hour to overnight hospitalization. Short observation may improve efficiency by allowing use of the same recovery bed and other resources for RMBs in additional patients. OBJECTIVE. The purpose of this study was to evaluate the frequency, timing, and nature of complications after RMB, as well as to identify characteristics associated with such complications. METHODS. This retrospective study included 576 patients (mean age, 64.9 years; 345 men, 231 women) who underwent percutaneous ultrasound- or CT-guided RMB at one of three hospitals, performed by 22 radiologists, between January 1, 2008, and June 1, 2020. The EHR was reviewed to identify postbiopsy complications, which were classified as bleeding-related or non-bleeding-related and as acute (< 24 hours), subacute (24 hours to 30 days), or delayed (> 30 days). Deviations from normal clinical management (analgesia, unplanned laboratory testing, or additional imaging) were identified. RESULTS. Acute and subacute complications occurred after 3.6% (21/576) and 0.7% (4/576) of RMBs, respectively. No delayed complication or patient death occurred. A total of 76.2% (16/21) of acute complications were bleeding-related. A deviation from normal clinical management occurred after 1.6% (9/551) of RMBs that had no associated postbiopsy complication. Among the 16 patients with bleeding-related acute complications, all experienced a deviation, with mean time to deviation of 56 ± 47 (SD) minutes (range, 10-162 minutes; ≤ 120 minutes in 13/16 patients). The five non-bleeding-related acute complications all presented at the time of RMB completion. The four subacute complications occurred from 28 hours to 18 days after RMB. Patients with, versus those without, a bleeding-related complication had a lower platelet count (mean, 197.7 vs 250.4 × 109/L, p = .01) and greater frequency of entirely endophytic renal masses (47.4% vs 19.6%, p = .01). CONCLUSION. Complications after RMB were uncommon and presented either within 3 hours after biopsy or more than 24 hours after biopsy. CLINICAL IMPACT. A 3-hour monitoring window after RMB before patient discharge (in the absence of deviation from normal clinical management and complemented by informing patients of the low risk of a subacute complication) may provide both safe patient management and appropriate resource utilization.