Update on Percutaneous Ablation for Sarcoma.

PURPOSE OF REVIEW: To provide an update on the current state of percutaneous thermal ablation in the treatment of sarcoma. RECENT FINDINGS: Data continue to accrue in support of ablation for local control and palliation of specific sarcoma subtypes such as extra-abdominal desmoid fibromatosis and for broader indications such as the treatment of oligometastatic disease. The synergistic possibilities of various combination therapies such as cryoablation and immunotherapy represent intriguing areas of active investigation. Histotripsy is an emerging non-invasive, non-thermal ablative modality that may further expand the therapeutic arsenal for sarcoma treatment. Percutaneous thermal ablation is a valuable tool in the multidisciplinary management of sarcoma, offering a minimally invasive adjunct to surgery and radiation therapy. Although there remains a paucity of high-level evidence specific to sarcomas, ablation techniques are demonstrably safe and effective for achieving local tumor control and providing pain relief in select patients and are of particular benefit in those with metastatic disease or requiring palliative care.

Percutaneous Cryoablation of Plasmacytomas: Oncologic Effectiveness and Adverse Events.

PURPOSE: To evaluate the oncologic outcomes and adverse events associated with cryoablation of plasmacytomas. MATERIALS AND METHODS: Retrospective review of an institutional percutaneous ablation database showed that 43 patients underwent 46 percutaneous cryoablation procedures for treatment of 44 plasmacytomas between May 2004 and March 2021. The treatment of 25 (25 of 44, 56.8%) tumors was augmented with bone consolidation/cementoplasty. The median patient age was 64 years (interquartile range [IQR], 54-69), and 30 of 43 (69.8%) patients were men. The median maximum plasmacytoma diameter was 5.0 cm (IQR, 3.1-7.0). Thirty of 44 (68.2%) tumors were periacetabular, vertebral, or located in the iliac wing. Twenty-nine of 44 (65.9%) cryoablated plasmacytomas were recurrent tumors after prior external beam radiation therapy (EBRT). Survival analyses were performed using the Kaplan-Meier method. Adverse events were graded using Society of Interventional Radiology criteria. RESULTS: The 5-year estimated local tumor recurrence-free survival was 85.3% (95% CI, 74.1%-98.1%), the 5-year estimated new plasmacytoma-free survival was 49.9% (95% CI, 33.9%-73.4%), and the 5-year estimated overall survival was 70.4% (95% CI, 56.9%-87.1%). Nine of 46 (19.6%) major adverse events occurred in 8 patients, including 3 of 46 (6.5%) new or progressive pathologic fractures at the ablation site requiring surgical intervention, 3 of 46 (6.5%) nerve injuries, 1 of 46 (2.2%) avascular necrosis and femoral head collapse, 1 of 46 (2.2%) septic arthritis, and 1 of 46 (2.2%) acute renal failure caused by rhabdomyolysis. CONCLUSIONS: Percutaneous cryoablation is a viable treatment option for patients with plasmacytomas, including those with recurrent plasmacytomas after EBRT. Postcryoablation adverse events are relatively common.

Thermoprotection of Neural Structures During Musculoskeletal Ablation.

Percutaneous thermal ablation is widely used for local control and palliation of a variety of lesions throughout the musculoskeletal system. In this setting, safe ablation is predicated on the avoidance of unintentional injury to vulnerable neural structures that are often in proximity to ablation targets. This article highlights key periprocedural considerations in musculoskeletal ablation and reviews the array of active and passive thermoprotective measures that are critical to safe and successful treatment.

International Validation of a Methicillin-Resistant Staphylococcus aureus Risk Assessment Tool for Skin and Soft Tissue Infections.

INTRODUCTION: To promote judicious prescribing of methicillin-resistant Staphylococcus aureus (MRSA)-active therapy for skin and soft tissue infections (SSTI), we previously developed an MRSA risk assessment tool. The objective of this study was to validate this risk assessment tool internationally. METHODS: A multicenter, prospective cohort study of adults with purulent SSTI was performed at seven international sites from July 2016 to March 2018. Patient MRSA risk scores were computed as follows: MRSA infection/colonization history (2 points); previous hospitalization, previous antibiotics, chronic kidney disease, intravenous drug use, human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), diabetes with obesity (1 point each). Predictive performance of MRSA surveillance percentage, MRSA risk score, and estimated MRSA probability (surveillance percentage adjusted by risk score) were quantified using the area under the receiver operating characteristic curves (aROC) and compared. Performance characteristics of different risk score thresholds across varying baseline MRSA prevalence were examined. RESULTS: Two hundred three patients were included. Common SSTI were wounds (28.6%), abscess (25.1%), and cellulitis with abscess (20.7%). Patients with higher risk scores were more likely to have MRSA (P < 0.001). The MRSA risk score aROC (95%CI) [0.748 (0.678-0.819)] was significantly greater than MRSA surveillance percentage [0.646 (0.569-0.722)] (P = 0.016). Estimated MRSA probability aROC [0.781 (0.716-0.845)] was significantly greater than surveillance percentage (P < 0.001) but not the risk score (P = 0.192). The estimated negative predictive value (NPV) of an MRSA score ≥ 1 (i.e., a score of 0) was greater than 90% when MRSA prevalence was 30% or less. CONCLUSION: The MRSA risk score and estimated MRSA probability were significantly more predictive of MRSA compared with surveillance percentage. An MRSA risk score of zero had high predictive value and could help avoid unnecessary empiric MRSA coverage in low-acuity patients. Further study, including impact of such risk assessment tools on prescribing patterns and outcomes are required before implementation.

Ablation for oligometastatic colorectal carcinoma in extrahepatic, extrapulmonary sites.

Treatment of metastatic colorectal carcinoma has evolved in the era of increasingly effective systemic therapies. Increasing survival rates provide opportunities for repeated focal therapies to be directed at limited metastatic disease. Surgical resection and other ablative therapies to eliminate oligometastases in the most common sites, namely liver and lung, have been proven to prolong survival. As such, patients develop additional sites of metastasis in the course of their disease, including adrenal, peritoneal, nodal, and skeletal metastases. Data supporting aggressive focal therapy for extrahepatic, extrapulmonary metastases are limited. This manuscript summarizes findings of surgical studies of cytoreduction in these patients, describes limited data from ablation case series that include these metastases, and presents a rationale for further investigation of thermal ablation within this patient population.

Bone ablations in peripheral skeleton: Rationale, techniques and evidence.

This article aims to disclose a consensus on the rationale, approaches, and the outcomes of bone ablations in the peripheral skeleton. Despite less numerous prospective studies about peripheral metastasis, interventional radiology has a role in this setting. Scrupulous attention for selection criteria, ablation technique, procedural steps, and clinical and imaging follow-up are required to provide optimal multidisciplinary care for oncologic patients.

Percutaneous Cryoablation of Large Tumors: Safety, Feasibility, and Technical Considerations.

INTRODUCTION: Large tumors may prove unsuitable for surgical cure or other local therapies due to their size, involvement of critical structures, prior non-ablative treatment failure, or coexisting disease burden. This study was performed to assess the safety and feasibility of percutaneous cryoablation for treatment of large tumors exceeding 6 cm in size, and to highlight the key technical considerations inherent to such cases. MATERIALS AND METHODS: This single-institution retrospective study identified 77 patients (42 male, 35 female; median age 55 years) who underwent 96 cryoablation procedures for treatment of 78 tumors (mean diameter 9.8 ± 3.6 cm) from 2008 through 2020. Technical success, procedure-related complications, mortality, oncologic outcomes, and procedural logistics were evaluated. Technical success was defined as ice ball extension at least 5 mm beyond the tumor margins. RESULTS: Intentional subtotal ablations were performed in 32% of cases due to tumor encroachment on vulnerable structures or as part of staged/combined therapies. Of the 68% of cases that were planned for complete ablation, the technical success rate was 100%. Major complications occurred after 19/96 (20%) procedures, with hemorrhage and acute kidney injury each occurring in 6/96 (6%). Post-procedural myositis occurred in 24/96 (25%) cases and was not considered a major complication in the absence of acute kidney injury. Local recurrence occurred in 2/23 (8.7%) of patients undergoing ablation for cure or local control at a median follow-up duration of 13 months. CONCLUSION: Percutaneous cryoablation may be used to treat large (> 6 cm) tumors with a high degree of technical success and an acceptable safety profile.

Feasibility and safety of percutaneous image-guided cryoablation of abdominal wall endometriosis.

PURPOSE: To evaluate the feasibility and safety of percutaneous image-guided cryoablation of abdominal wall endometriosis (AWE). MATERIALS AND METHODS: A retrospective review of percutaneous cryoablation (CT or MR) of AWE was performed from January 2018 to December 2020. Eighteen patients were identified from an internal percutaneous ablation database. Technical success, complications, and outcomes were analyzed according to standard nomenclature. RESULTS: Patients comprised 18 females (mean age 36.9 years) who underwent 18 cryoablation procedures to treat 23 AWE deposits. Three of the 18 cases were performed under MR guidance, while the remaining 15 employed CT guidance. Technical success was achieved in all 18 cases (100%). Fifteen of 18 patients (83%) had biopsy proven AWE deposits prior to treatment. Hydrodisplacement was used to displace adjacent bowel, bladder, or neurovascular structures in 13/18 cases (72%). The mean number of probes used per case was 3. Sixteen of 23 (70%) of AWE deposits had imaging follow-up (median 85 days). Of the 16 lesions with imaging follow-up, 15 (94%) demonstrated no residual enhancement or T1 hyperintensity at the treatment site and 1 lesion (6%) demonstrated residual/progressive disease. At clinical follow-up, 13 of 14 (93%) patients reported improvement in AWE-related symptoms. Eleven patients had clinically documented pain scores before and after ablation and all demonstrated substantial symptomatic improvement. No society of interventional radiology (SIR) major complications were observed. CONCLUSIONS: Percutaneous cryoablation of AWE is feasible with a favorable safety profile. Further longitudinal studies are needed to document durable response over time.

Cryoablation for Palliation of Painful Bone Metastases: The MOTION Multicenter Study.

Purpose: To assess the clinical effectiveness of cryoablation for palliation of painful bone metastases. Materials and Methods: MOTION (Multicenter Study of Cryoablation for Palliation of Painful Bone Metastases) (ClinicalTrials.gov NCT02511678) was a multicenter, prospective, single-arm study of adults with metastatic bone disease who were not candidates for or had not benefited from standard therapy, that took place from February 2016 to March 2018. At baseline, participants rated their pain using the Brief Pain Inventory-Short Form (reference range from 0 to 10 points); those with moderate to severe pain, who had at least one metastatic candidate tumor for ablation, were included. The primary effectiveness endpoint was change in pain score from baseline to week 8. Participants were followed for 24 weeks after treatment. Statistical analyses included descriptive statistics and logistic regression to evaluate changes in pain score over the postprocedure follow-up period. Results: A total of 66 participants (mean age, 60.8 years ± 14.3 [standard deviation]; 35 [53.0%] men) were enrolled and received cryoablation; 65 completed follow-up. Mean change in pain score from baseline to week 8 was -2.61 points (95% CI: -3.45, -1.78). Mean pain scores improved by 2 points at week 1 and reached clinically meaningful levels (more than a 2-point decrease) after week 8; scores continued to improve throughout follow-up. Quality of life improved, opioid doses were stabilized, and functional status was maintained over 6 months. Serious adverse events occurred in three participants. Conclusion: Cryoablation of metastatic bone tumors provided rapid and durable pain palliation, improved quality of life, and offered an alternative to opioids for pain control.Keywords: Ablation Techniques, Metastases, Pain Management, Radiation Therapy/OncologySupplemental material is available for this article.© RSNA, 2021.

A Single-Institution Experience in Percutaneous Image-Guided Cryoablation of Lymph Node Metastases.

OBJECTIVE. The purpose of this study was to assess the feasibility, safety, and efficacy of percutaneous cryoablation for the treatment of lymph node metastases. MATERIALS AND METHODS. In this single-institution retrospective study 55 patients were identified who underwent CT-guided cryoablation of metastatic lymph nodes between November 2006 and September 2019. Patient demographics, disease characteristics, and procedural details were recorded. The primary endpoints were technical success and major complications. The secondary endpoints were time to local and time to distant progression. Complications were graded according to the Society of Interventional Radiology consensus guidelines. RESULTS. The study sample comprised 55 patients (42 men, 13 women; mean age 64 ± 12 years) who underwent 61 cryoablation procedures to treat 65 lymph node metastases. Targeted nodes measured 1.7 ± 1.2 cm in mean short-axis diameter. Technical success was achieved in 60 of 61 cryoablation procedures (98%). Adjunctive maneuvers performed to protect adjacent structures included hydrodissection (n = 40), ureteral stenting (n = 3), and neural monitoring (n = 3). There were two Society of Interventional Radiology major complications (3%): pneumothorax (n = 1) and bleeding (n = 1). Local tumor control was achieved in treatment of 53 of 65 (82%) nodal metastases within a median of 25 months (range, 1-121 months) of follow-up. Local progression occurred in 12 of 65 cases (18%); the median time to recurrence was 11 months. CONCLUSION. Percutaneous cryoablation of nodal metastases is feasible and safe. Further investigation is warranted to assess the long-term efficacy of this technique and to define its role in oncologic care.

Image-guided tumor ablation in gynecologic oncology: Review of interventional oncology techniques and case examples highlighting a collaborative, multidisciplinary program.

As interventional oncology services within radiology mature, image-guided ablation techniques are increasingly applied to recurrent gynecologic malignancies. Ablation may be performed using thermal techniques like cryoablation, microwave ablation, or radiofrequency ablation, as well as non-thermal ones, such as focused ultrasound or irreversible electroporation. Feasibility and approach depend on tumor type, size, number, anatomic location, proximity of critical structures, and goals of therapy. Current indications include local control of limited metastatic disease or palliation of painful bone metastases refractory or unsuitable to conventional therapies. Technical aspects of these procedures, including methods to protect nearby critical structures are presented through illustrative examples. Cases amenable to image-guided ablation include, but are not limited to, hepatic or pulmonary metastases, musculoskeletal metastases, retroperitoneal nodal metastases, pelvic side wall disease, abdominal wall disease, and vaginal or vulvar tumors. Protective maneuvers, such as hydro-displacement of bowel, neuromonitoring, and retrograde pyeloperfusion through ureteral stents, permit safe ablation despite close proximity to vulnerable nerves or organs. Image-guided ablation offers an alternative modality to achieve local tumor control without the risks associated with surgery or systemic treatment in appropriately selected patients. A multidisciplinary approach to use of image-guided ablation includes collaboration between gynecologic oncology, interventional radiology, anesthesia, urology and radiation oncology teams allowing for appropriate patient-centered case selection. Long-term follow up and additional studies are needed to determine the oncologic benefits of such techniques.

AUTOMATED DETECTION OF MALARIAL RETINOPATHY USING TRANSFER LEARNING.

Cerebral Malaria (CM) is a severe neurological syndrome of malaria mainly found in children and is associated with highly specific retinal lesions. The manifestation of these indications of CM in the retina is called malarial retinopathy (MR). All patients showing clinical signs of CM are commonly diagnosed and treated accordingly; however, 23% of them are misdiagnosed as they suffer from another infection with identical clinical symptoms. Due to these underlying symptoms, the false positive cases may go untreated and could result in death of the patients. A diagnostic test is needed that is highly specific in order to reduce false positives. The purpose of this study to demonstrate a technique based on a transfer learning technique using images from three different retinal cameras to identify the hemorrhages and whitening lesions in the retina which can accurately identify the patients with MR. The MR detection model gives a specificity of 100% and a sensitivity of 90% with an AUC of 0.98. The algorithm demonstrates the potential of accurate MR detection with a low-cost retinal camera.

Improving Root Cause Analysis of Patient Safety Events in Radiology.

Patient safety events occur in health care, and root cause analysis (RCA) meetings held after these incidents often reveal valuable insights into systemic barriers between optimal processes or stated policies and actual practice, providing critical opportunities for improvement. The patient safety team that facilitates RCA meetings in the radiology department at the authors' institution received feedback suggesting dissatisfaction with the RCA process. The team followed a structured process improvement framework to analyze the root causes of this dissatisfaction and create a better system. Using a post-RCA survey to target satisfaction scores as an improvement goal, the team successfully increased participant and facilitator satisfaction levels with sustained results. The patient safety team applied structured process improvement methodologies to their own daily work, learning lessons about measuring difficult processes and choosing appropriate metrics, the benefits of standardized work, and how to continuously improve a quality program. In the course of improving the satisfaction of employees participating in the RCA process, a more robust, continuously improving patient safety program has emerged to enhance the ability of those within the department to report, learn from, and hopefully prevent patient safety events in the future.©RSNA, 2020.

Implementing a Radiology Residency Quality Curriculum to Develop Physician Leaders and Increase Value for Patients.

Diagnostic and interventional radiology residency programs must educate trainees on quality and patient safety topics to meet board requirements and prepare residents to become effective physician leaders. A quality curriculum should encompass process improvement methodology as well as instruction about crucial patient safety subjects. The authors have developed a standardized and structured approach to fulfill this need using didactic and experiential learning. The educational format includes short lectures, peer-to-peer instruction, and self-study, with the value of presented information reinforced by physician leaders and process improvement specialists. Equally important is a structured experience in departmental quality improvement wherein trainees learn the collaborative nature of effective durable process change in areas of interest to them. This curriculum is implemented during the 3rd year of radiology residency to leverage residents' knowledge and experience with radiology workflows and proximity to the American Board of Radiology Core Exam. Feedback from educators and trainees as well as objective examination data support this approach. This article shares guidance and lessons learned from the authors' radiology residency educational efforts and offers a framework for successful implementation of a comprehensive quality curriculum at any residency training program. This curriculum serves the dual purpose of developing skilled future physician leaders and promoting value for patients. ©RSNA, 2020.

Percutaneous cryoablation of abdominal wall endometriosis: the Mayo Clinic approach.

Abdominal wall endometriosis (AWE) is a rare form of endometriosis that often results in substantial pain and debility. The current treatment algorithm for AWE is not well established. The purpose of this review is to describe the Mayo Clinic experience with thermal ablation of symptomatic AWE as well as to review current imaging and interventional literature regarding the diagnosis and treatment of AWE.

Simulation of a radiobiology facility for the Centre for the Clinical Application of Particles.

The Centre for the Clinical Application of Particles' Laser-hybrid Accelerator for Radiobiological Applications (LhARA) facility is being studied and requires simulation of novel accelerator components (such as the Gabor lens capture system), detector simulation and simulation of the ion beam interaction with cells. The first stage of LhARA will provide protons up to 15 MeV for in vitro studies. The second stage of LhARA will use a fixed-field accelerator to increase the energy of the particles to allow in vivo studies with protons and in vitro studies with heavier ions. BDSIM, a Geant4 based accelerator simulation tool, has been used to perform particle tracking simulations to verify the beam optics design done by BeamOptics and these show good agreement. Design parameters were defined based on an EPOCH simulation of the laser source and a series of mono-energetic input beams were generated from this by BDSIM. The tracking results show the large angular spread of the input beam (0.2 rad) can be transported with a transmission of almost 100% whilst keeping divergence at the end station very low (<0.1 mrad). The legacy of LhARA will be the demonstration of technologies that could drive a step-change in the provision of proton and light ion therapy (i.e. a laser source coupled to a Gabor lens capture and a fixed-field accelerator), and a system capable of delivering a comprehensive set of experimental data that can be used to enhance the clinical application of proton and light ion therapy.

Procedure-Related Pain During Image-Guided Percutaneous Biopsies: A Retrospective Study of Prevalence and Predictive Factors.

OBJECTIVE. The purpose of this study was to evaluate the prevalence and severity of pain reported during image-guided percutaneous biopsies and to identify factors associated with increased reported pain. MATERIALS AND METHODS. In this retrospective study, a database of adult patients who underwent CT- or ultrasound-guided percutaneous core needle biopsy between July 22, 2013, and February 1, 2018, was reviewed. Data collected included patient age and sex, biopsy site, biopsy type (lesion or parenchymal), needle gauge, number of passes, use of sedation, and whether it was the patient's first recorded biopsy. The maximum procedure-related pain reported on a 0-10 numeric rating scale was recorded. Multivariable logistic regression with generalized estimating equations was used to assess the association between covariates and patient-reported pain. RESULTS. A total of 13,344 biopsy procedures were performed in 10,474 patients. Patients reported no pain (0 of 10 scale) during 9765 (73.2%) procedures. Female sex, younger age at biopsy, undergoing IV sedation, and larger needle diameter were all associated with increases in patient-reported pain. Biopsies of renal allografts were the least likely to be painful, followed by hepatic allografts. CONCLUSION. Patients typically report mild or no pain from image-guided biopsy performed by radiologists. Younger patients and women report greater pain. This information can assist preprocedural counseling and reassurance of patients and may help them predict procedure-related patient needs.

Oncologic Outcomes Following Partial Nephrectomy and Percutaneous Ablation for cT1 Renal Masses.

BACKGROUND: Long-term data comparing partial nephrectomy (PN) and thermal ablation are lacking. OBJECTIVE: To update our experience with PN, percutaneous radiofrequency ablation (RFA), and percutaneous cryoablation for cT1 renal masses. DESIGN, SETTING, AND PARTICIPANTS: A total of 1798 patients with primary cT1N0M0 renal masses treated between 2000 and 2011 at Mayo Clinic were identified. INTERVENTION: Percutaneous ablation versus PN. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Cancer-specific survival (CSS) was estimated using the Kaplan-Meier method. Local recurrence, metastases, and death from renal cell carcinoma (RCC) were compared with propensity-score-adjusted Cox models. RESULTS AND LIMITATIONS: Among 1422 cT1a patients, 1055, 180, and 187 underwent PN, RFA, and cryoablation with median clinical follow-up of 9.4, 7.5, and 6.3yr, respectively. Comparisons of RFA with PN resulted in hazard ratios (HRs) of 1.49 (95% confidence interval [CI] 0.55-4.04, p=0.4), 1.46 (95% CI 0.41-5.19, p=0.6), and 1.99 (95% CI 0.29-13.56, p=0.5) for local recurrence, metastases, and death from RCC. Comparisons of cryoablation to PN resulted in HRs of 1.88 (95% CI 0.76-4.66, p=0.18), 0.23 (95% CI 0.03-1.72, p=0.15), and 0.29 (95% CI 0.01-6.11, p=0.4) for these same outcomes. Five-year CSS was 99%, 96%, and 100% for PN, RFA, and cryoablation, respectively. Among 376 cT1b patients, 324 and 52 underwent PN and cryoablation with median clinical follow-up of 8.7 and 6.0yr, respectively. Comparisons of cryoablation with PN resulted in HRs of 1.22 (95% CI 0.33-4.48, p=0.8), 0.95 (95% CI 0.21-4.38, p>0.9), and 1.94 (95% CI 0.42-8.96, p=0.4) for local recurrence, metastases, and death from RCC, respectively. Five-year CSS was 98% and 91% for PN and cryoablation, respectively. Limitations include retrospective review and selection bias. CONCLUSIONS: With mature follow-up at a single institution, percutaneous ablation appears to have acceptable results for cT1 renal tumors and is appropriate for patients with a contraindication for surgery. For cT1a patients, clinically relevant differences between PN and ablation are unlikely, and treatment choice should involve shared decision making. For cT1b patients, death from RCC was more common with cryoablation, and large differences in this outcome cannot be ruled out. Further research is needed to confirm the oncologic effectiveness of cryoablation in the cT1b setting. PATIENT SUMMARY: With appropriate patient triage, partial nephrectomy and percutaneous ablation can be used to treat cT1 renal masses, although additional follow-up and further study are still needed.

Frequency of Bleeding Complications After Percutaneous Core Needle Biopsy and the Association With Aspirin Usage and Length of Aspirin Discontinuation.

OBJECTIVE. The purpose of this study is to report the frequency of major bleeding after percutaneous image-guided core biopsy and its association with aspirin usage and duration of prebiopsy aspirin abstinence. MATERIALS AND METHODS. A retrospective review of percutaneous image-guided core biopsies performed at our institution between September 1, 2005, and September 1, 2016, was performed (n = 30,966). Patients were excluded if aspirin usage data were missing (n = 633). Bleeding complications were defined using the Common Terminology Criteria for Adverse Events and were considered significant if they were grade 3 or higher. Multivariate models were adjusted for age, sex, platelet count, international normalized ratio, and biopsy target. Three categorizations of aspirin use were examined: any use within 10 days before biopsy, duration of abstinence (> 10 days or no aspirin, 8-10 days, 4-7 days, and 0-3 days before biopsy), and use on the day of biopsy. Associations with bleeding complications were modeled using logistic regression models. A p < 0.05 was considered significant. RESULTS. The study included 30,333 biopsies in 21,938 subjects (57% male; median age, 60 years; interquartile range, 49-70 years). Of the biopsies, 7921 (26.1%) were performed in patients who received aspirin within 10 days of biopsy, and 3761 (47.5%) of those biopsies were performed in patients who took aspirin within 3 days. Ninety-eight (0.32%) significant bleeding complications occurred overall, including 34 (0.43%) in patients who used aspirin within 10 days before biopsy (odds ratio, 1.5; 95% CI, 0.96-2.3; p = 0.08). Duration of abstinence was associated with a significantly increased bleeding risk only between 0-3 days versus more than 10 days or no aspirin (odds ratio, 2.1; 95% CI, 1.3-3.6; p = 0.004). Aspirin use on the day of biopsy showed the greatest increase in risk (1.9%; odds ratio, 6.6; 95% CI, 3.8-11.5; p < 0.001). CONCLUSION. Significant bleeding complications after biopsy remain rare even among patients with recent aspirin usage, although shorter duration of prebiopsy abstinence increases bleeding risk, most significantly if aspirin is taken the day of biopsy.