Percutaneous Robotics in Interventional Radiology.

The accuracy of the robotic device not only relies on a reproducible needle advancement, but also on the possibility to correct target movement at chosen checkpoints and to deviate from a linear to a nonlinear trajectory. We report our experience in using the robotic device for the insertion of trocar needles in CT guided procedures. The majority of procedures were targeted organ biopsies in the chest abdomen or pelvis. The accuracy of needle placement after target adjustments did not significantly differ from those patients where a linear trajectory could be used. The steering capabilities of the robot allow correction of target movement of the fly.

Safety and Efficacy of Concurrent Atezolizumab/Bevacizumab or Nivolumab Combination Therapy with Yttrium-90 Radioembolization of Advanced Unresectable Hepatocellular Carcinoma.

To evaluate the safety and efficacy of combining yttrium-90 radioembolization (Y90-RE) with immune checkpoint inhibitor therapy, consecutive advanced unresectable hepatocellular carcinoma (HCC) patients treated between 2016 and 2022 with atezolizumab/bevacizumab or nivolumab within three-months pre- and post-Y90-RE were retrospectively evaluated. Tumor response and treatment-related clinical/laboratory adverse events (AE) were assessed at 1 and 6 months, as well as differences in clinical and laboratory variables and median overall survival (OS) from initial treatment (whether it was Y90-RE or systemic therapy) between the two cohorts. A total of 19 patients (10 atezolizumab/bevacizumab; 9 nivolumab), comprising 84% males with median age 69 years, met the inclusion criteria. Compared to the atezolizumab/bevacizumab group, there were less males (100% vs. 67%; p = 0.02) and more ECOG ≥ 2 patients in the nivolumab group (0% vs. 33%; p = 0.02). Baseline characteristics or incidence of 6-month post-treatment any-grade AE (60% vs. 56%; p = 0.7), grade ≥ 3 AE (0% vs. 11%; p = 0.3), objective response (58% total, 60% vs. 56%; p = 0.7), and complete response (16% total; 10% vs. 22%; p = 0.8) were similar between the atezolizumab/bevacizumab and the nivolumab cohorts. Median OS was 12.9 months for the whole cohort, 16.4 months for nivolumab, and 10.7 months for atezolizumab/bevacizumab. Among patients with advanced unresectable HCC, the utilization of Y90-RE concurrently or within 90 days of nivolumab or atezolizumab/bevacizumab immunotherapy, appears to be well-tolerated and with a low incidence of severe AE.

Decoding radiology reports: Potential application of OpenAI ChatGPT to enhance patient understanding of diagnostic reports.

PURPOSE: To evaluate the complexity of diagnostic radiology reports across major imaging modalities and the ability of ChatGPT (Early March 2023 Version, OpenAI, California, USA) to simplify these reports to the 8th grade reading level of the average U.S. adult. METHODS: We randomly sampled 100 radiographs (XR), 100 ultrasound (US), 100 CT, and 100 MRI radiology reports from our institution's database dated between 2022 and 2023 (N = 400). These were processed by ChatGPT using the prompt "Explain this radiology report to a patient in layman's terms in second person: ". Mean report length, Flesch reading ease score (FRES), and Flesch-Kincaid reading level (FKRL) were calculated for each report and ChatGPT output. T-tests were used to determine significance. RESULTS: Mean report length was 164 ± 117 words, FRES was 38.0 ± 11.8, and FKRL was 10.4 ± 1.9. FKRL was significantly higher for CT and MRI than for US and XR. Only 60/400 (15%) had a FKRL <8.5. The mean simplified ChatGPT output length was 103 ± 36 words, FRES was 83.5 ± 5.6, and FKRL was 5.8 ± 1.1. This reflects a mean decrease of 61 words (p < 0.01), increase in FRES of 45.5 (p < 0.01), and decrease in FKRL of 4.6 (p < 0.01). All simplified outputs had FKRL <8.5. DISCUSSION: Our study demonstrates the effective use of ChatGPT when tasked with simplifying radiology reports to below the 8th grade reading level. We report significant improvements in FRES, FKRL, and word count, the last of which requires modality-specific context.

Use of Metformin and Survival in Patients with Hepatocellular Carcinoma (HCC) Undergoing Liver Directed Therapy: Analysis of a Nationwide Cancer Registry.

BACKGROUND: Examine the association of metformin use and overall survival (OS) in patients with HCC undergoing image-guided liver-directed therapy (LDT): ablation, transarterial chemoembolization (TACE), or Yttrium-90 radioembolization (Y90 RE). METHODS: Using National Cancer Institute Surveillance, Epidemiology, and End Results registry and Medicare claims databases between 2007 and 2016, we identified patients ≥ 66 years who underwent LDT within 30 days of HCC diagnosis. Patients with liver transplant, surgical resection, and other malignancies were excluded. Metformin use was identified by at least two prescription claims within 6 months before LDT. OS was measured by time between first LDT and death or last Medicare observation. Comparisons were performed between both all and diabetic patients on and not on metformin. RESULTS: Of 2746 Medicare beneficiaries with HCC undergoing LDT, 1315 (47.9%) had diabetes or diabetes-related complications. Among all and diabetic patients, 433(15.8%) and 402 (30.6%) were on metformin respectively. Median OS was greater for patients on metformin (19.6 months, 95% CI 17.1-23.0) vs those not (16.0 months, 15.0-16.9; p = 0.0238). Patients on metformin had lower risk of death undergoing ablation (HR 0.70; 0.51-0.95; p = 0.0239) and TACE (HR 0.76, 0.66-0.87; p = 0.0001), but not Y90 RE (HR1.22, 0.89-1.69; p = 0.2231). Among diabetics, OS was greater for those on metformin vs those not (HR 0.77, 0.68-0.88; p < 0.0001). Diabetic patients on metformin had longer OS undergoing TACE (HR 0.71, 0.61-0.83; p < 0.0001), but not ablation (HR 0.74, 0.52-1.04; p = 0.0886) or Y90 RE (HR 1.26, 0.87-1.85; p = 0.2217). CONCLUSION: Metformin use is associated with improved survival in HCC patients undergoing TACE and ablation.

Supervised segmentation for guiding peripheral revascularization with forward-viewing, robotically steered ultrasound guidewire.

BACKGROUND: Approximately 500 000 patients present with critical limb ischemia (CLI) each year in the U.S., requiring revascularization to avoid amputation. While peripheral arteries can be revascularized via minimally invasive procedures, 25% of cases with chronic total occlusions are unsuccessful due to inability to route the guidewire beyond the proximal occlusion. Improvements to guidewire navigation would lead to limb salvage in a greater number of patients. PURPOSE: Integrating ultrasound imaging into the guidewire could enable direct visualization of routes for guidewire advancement. In order to navigate a robotically-steerable guidewire with integrated imaging beyond a chronic occlusion proximal to the symptomatic lesion for revascularization, acquired ultrasound images must be segmented to visualize the path for guidewire advancement. METHODS: The first approach for automated segmentation of viable paths through occlusions in peripheral arteries is demonstrated in simulations and experimentally-acquired data with a forward-viewing, robotically-steered guidewire imaging system. B-mode ultrasound images formed via synthetic aperture focusing (SAF) were segmented using a supervised approach (U-net architecture). A total of 2500 simulated images were used to train the classifier to distinguish the vessel wall and occlusion from viable paths for guidewire advancement. First, the size of the synthetic aperture resulting in the highest classification performance was determined in simulations (90 test images) and compared with traditional classifiers (global thresholding, local adaptive thresholding, and hierarchical classification). Next, classification performance as a function of the diameter of the remaining lumen (0.5 to 1.5 mm) in the partially-occluded artery was tested using both simulated (60 test images at each of 7 diameters) and experimental data sets. Experimental test data sets were acquired in four 3D-printed phantoms from human anatomy and six ex vivo porcine arteries. Accuracy of classifying the path through the artery was evaluated using microcomputed tomography of phantoms and ex vivo arteries as a ground truth for comparison. RESULTS: An aperture size of 3.8 mm resulted in the best-performing classification based on sensitivity and Jaccard index, with a significant increase in Jaccard index (p < 0.05) as aperture diameter increased. In comparing the performance of the supervised classifier and traditional classification strategies with simulated test data, sensitivity and F1 score for U-net were 0.95 ± 0.02 and 0.96 ± 0.01, respectively, compared to 0.83 ± 0.03 and 0.41 ± 0.13 for the best-performing conventional approach, hierarchical classification. In simulated test images, sensitivity (p < 0.05) and Jaccard index both increased with increasing artery diameter (p < 0.05). Classification of images acquired in artery phantoms with remaining lumen diameters ≥ 0.75 mm resulted in accuracies > 90%, while mean accuracy decreased to 82% when artery diameter decreased to 0.5 mm. For testing in ex vivo arteries, average binary accuracy, F1 score, Jaccard index, and sensitivity each exceeded 0.9. CONCLUSIONS: Segmentation of ultrasound images of partially-occluded peripheral arteries acquired with a forward-viewing, robotically-steered guidewire system was demonstrated for the first-time using representation learning. This could represent a fast, accurate approach for guiding peripheral revascularization.

Yttrium-90 Radiation Segmentectomy of Hepatocellular Carcinoma: A Comparative Study of the Effectiveness, Safety, and Dosimetry of Glass-Based versus Resin-Based Microspheres.

PURPOSE: To evaluate the differences in safety, effectiveness, and dosimetry between glass-based and resin-based ablative yttrium-90 (90Y) transarterial radioembolization (TARE) of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Using the modified Response Evaluation Criteria in Solid Tumors and Common Terminology Criteria for Adverse Events, both tumor response and adverse events (AEs) were assessed at 3 months after 90Y-TARE. Post procedure 90Y-bremsstrahlung single-photon emission computed tomography/computed tomography voxel-based dosimetry analysis was used to create tumor dose (TD) and normal tissue dose (NTD) volume histograms, and to calculate tumor particle loading and specific activity. The TD and NTD receiver operating characteristic curves evaluated the dose threshold able to predict objective (partial or complete) and complete tumor responses in addition to any-grade and grade ≥3 AE incidences. The chi-square test and Student t-test were used to assess variable differences where appropriate. RESULTS: Between 2019 and 2020, 81 patients with HCC (20 in the resin-based cohort and 61 in the glass-based cohort) underwent ablative 90Y-TARE. The resin-based cohort had more males (89% vs 65%, P = .03), lower tumor-to-normal ratio (1.81 ± 0.39 vs 2.22 ± 0.94, P = .03), higher tumor particle loading (40,172 particles/mL ± 28,039 vs 17,081 particles/mL ± 12,555, P = .0001), lower specific activity (158 Bq/particle ± 3 vs 1,058 Bq/particle ± 331, P = .001), and lower mean TD (308 Gy ± 210 vs 794 Gy ± 523, P = .0002) than the glass-based cohort. No significant differences in baseline characteristics or posttreatment AEs were noted. The overall objective and complete response rates were 85% (95% resin-based vs 82% glass-based; P = .1) and 65% (95% resin-based vs 56% glass-based; P = .003), respectively. The mean TD thresholds able to predict the objective and complete responses were 176 Gy and 247 Gy for resin-based radioembolization and 290 Gy and 481 Gy for glass-based radioembolization, respectively. A maximum NTD of 999 Gy predicted any-grade AEs in glass-based ablative 90Y-TARE. CONCLUSIONS: Compared with glass-based ablative 90Y-TARE, resin-based ablative 90Y-TARE can offer comparable safety and effectiveness profiles for patients with HCC. The impact of the significantly different tumor particle loading, particle specific activities, and delivered TDs on tumor response outcomes merits further investigation.

Voxel-based dosimetry predicting treatment response and related toxicity in HCC patients treated with resin-based Y90 radioembolization: a prospective, single-arm study.

BACKGROUND: There is an increasing body of evidence indicating Y90 dose thresholds for tumor response and treatment-related toxicity. These thresholds are poorly studied in resin Y90, particularly in hepatocellular carcinoma (HCC). PURPOSE: To evaluate the efficacy of prospective voxel-based dosimetry for predicting treatment response and adverse events (AEs) in patients with HCC undergoing resin-based Y90 radioembolization. MATERIALS AND METHODS: This correlative study was based on a prospective single-arm clinical trial (NCT04172714), which evaluated the efficacy of low/scout (555 MBq) activity of resin-based Y90 for treatment planning. Partition model was used with goal of tumor dose (TD) > 200 Gy and non-tumoral liver dose (NTLD) < 70 Gy for non-segmental therapies. Single compartment dose of 200 Gy was used for segmentectomies. Prescribed Y90 activity minus scout activity was administered for therapeutic Y90 followed by Y90-PET/CT. Sureplan® (MIM Software, Cleveland, OH) was used for dosimetry analysis. Treatment response was evaluated at 3 and 6 months. Receiver operating characteristic curve determined TD response threshold for objective response (OR) and complete response (CR) as well as non-tumor liver dose (NTLD) threshold that predicted AEs. RESULTS: N = 30 patients were treated with 33 tumors (19 segmental and 14 non-segmental). One patient died before the first imaging, and clinical follow-up was excluded from this analysis. Overall, 26 (81%) of the tumors had an OR and 23 (72%) had a CR. A mean TD of 253 Gy predicted an OR with 92% sensitivity and 83% specificity (area under the curve (AUC = 0.929, p < 0.001). A mean TD of 337 Gy predicted a CR with 83% sensitivity and 89% specificity (AUC = 0.845, p < 0.001). A mean NTLD of 81 and 87 Gy predicted grade 3 AEs with 100% sensitivity and 100% specificity in the non-segmental cohort at 3- and 6-month post Y90, respectively. CONCLUSION: In patients with HCC undergoing resin-based Y90, there are dose response and dose toxicity thresholds directly affecting outcomes. CLINICAL TRIAL NUMBER: NCT04172714.

Correlation of Non-tumoral Liver Dose with Treatment-Related Adverse Events in Patients with Hepatocellular Carcinoma Treated with Glass-Based Yttrium-90 Radioembolization.

PURPOSE: To evaluate the relationship between non-tumor liver (NTL) dose and adverse events (AE) in patients with hepatocellular carcinoma (HCC) treated with glass-based Yttrium-90 radioembolization (Y90-RE). MATERIALS AND METHODS: A retrospective analysis of patients with HCC treated with Y90-RE between 2013 and 2018 was performed. Baseline characteristics including demographics and Y90-RE treatment approach were captured. Common Terminology Criteria for Adverse Events v5 was assessed at months 3 and 6 post-treatment. Using voxel-based dosimetry with MIM Software V. 6.9, dose-volume histograms of treated area of liver were created. Receiver operator characteristic curve was used to determine NTL dose threshold predicting AEs. Multivariate analysis was used to determine independent clinical factors of predicting severe AEs. Chi-square analysis was used to compare proportions. RESULTS: Two hundred and twenty-nine consecutive patients (115(50.2%) lobar and 114(49.8%) segmental) were included. At 3 months, there was a lower rate of any grade AE (55(46%) segmental and 36(31%) lobar, p = 0.009) and increased rate of severe AEs for lobar compared to segmental (2(2%) segmental and 9(8%) lobar, p = 0.029). At 6 months, severe AEs were greater for lobar than segmental (1(1%) segmental vs 10(9%) lobar, p = 0.005). For lobar Y90-RE, mean NTL dose of 112 Gy predicted severe AE (89% sensitivity and 91% specificity (AUC = 0.95, p = < 0.0001) at 3 and 6 months. For the segmental group, no significant association was found between NTL dose and severe treatment-related AE at 3 and 6 months. CONCLUSION: In patients with HCC undergoing glass-based lobar Y90-RE, NTL dose of > 112 Gy is associated with severe treatment-related AEs at 3-6 months.

Impact of drainage catheter material, size, and anti-dislodgement mechanism on percutaneous nephrostomy exchange intervals: a systematic review protocol.

Background: Percutaneous nephrostomy (PCN) is a commonly performed procedure by interventional radiology and urology to treat urinary obstruction. In this procedure, a catheter is percutaneously placed into the renal pelvis for urinary diversion or hemorrhagic cystitis. Material type, catheter size, and catheter shape (anti-dislodgement feature) ultimately contribute to the inherent traits of longevity in drainage catheter device. Reviewing the relative strengths or weaknesses of products in the existing clinical market may help clinicians critically appraise the devices they use with evidence-based findings from this review. Furthermore, a deeper understanding of the relative strengths and weaknesses of existing devices may help inform the next generation of drainage catheter devices to prolong the interval between exchanges without detriment to patient safety. Methods: The following electronic databases will be queried: PubMed, Web of Science, Cochrane from their inception to January 2023 to identify randomized controlled trials (RCTs) and cohort studies to investigate the differences that our interventions of catheter material, size, and dislodgement mechanism will have on the exchange interval (standard of care 90 days vs. 60 days vs. 45 days vs. 30 days). The primary outcomes will be the drainage catheter exchange frequency. Ethics and dissemination: We aim to share our findings through high-impact peer reviewed journals. As drainage catheters and minimally invasive interventional radiology procedures become more popular, it is important for healthcare providers taking case of these populations to understand which variables might optimize patient care and minimize emergent exchanges. Data will be made available to readers. Registration: PROSPERO ( CRD42023432788, 16 June 2023).

Study Protocol: Efficacy and Safety of Radioembolization (REM) as an Early Modality (EM) Therapy for Metastatic Breast Cancer (BR) to the Liver with Y90 (REMEMBR Y90).

PURPOSE: The primary objective of the REMEMBR Y90 study is to evaluate the efficacy of Yttrium-90 (Y90) radioembolization in patients with breast cancer metastases to the liver as a 2nd or 3rd line treatment option with systemic therapy by assessing liver-specific and overall progression-free survival. Secondary objectives include quality of life, overall survival benefit, and toxicity in relation to patients' tumor biology. MATERIALS AND METHODS: This trial is a multi-center, prospective, Phase 2, open-label, IRB-approved, randomized control trial in the final phases of activation. Eligible patients include those over 18 years of age with metastatic breast cancer to the liver with liver-only or liver-dominant disease, and history of tumor progression on 1-2 lines of chemotherapy. 60 patients will be randomized to radioembolization with chemotherapy versus chemotherapy alone. Permissible regimens include capecitabine, eribulin, vinorelbine, and gemcitabine within 2 weeks of enrollment for every patient. Patients receiving radioembolization will receive lobar or segmental treatment within 1-6 weeks of enrollment depending on their lesion. After final radioembolization, patients will receive clinical and imaging follow-up every 12-16 weeks for two years, including contrast-enhanced computed tomography or magnetic resonance imaging of the abdomen and whole-body positron emission tomography/computed tomography. DISCUSSION: This study seeks to elucidate the clinical benefit and toxicity of Y90 in patients with metastatic breast cancer to the liver who are receiving minimal chemotherapy. Given previous data, it is anticipated that the use of Y90 and chemotherapy earlier in the metastatic disease course would improve survival outcomes and reduce toxicity. LEVEL OF EVIDENCE: Level 1b, Randomized Controlled Trial. TRIAL REGISTRATION NUMBER: NCT05315687 on clinicaltrials.gov.

Cooled Radiofrequency Ablation for Chronic Joint Pain Secondary to Hip and Shoulder Osteoarthritis.

Osteoarthritis (OA) of the shoulder and hip is a leading cause of physical disability and mental distress. Traditional nonsurgical management alone is often unable to completely address the associated chronic joint pain. Moreover, a large number of patients are not eligible for joint replacement surgery owing to comorbidities or cost. Radiofrequency ablation (RFA) of articular sensory nerve fibers can disrupt the transmission of nociceptive signals by neurolysis, thereby providing long-term pain relief. A subtype of RFA, cooled RFA (CRFA), utilizes internally cooled electrodes to generate larger ablative zones compared with standard RFA techniques. Given the complex variable innervation of large joints such as the glenohumeral and hip joints, a larger ablative treatment zone, such as that provided by CRFA, is desired to capture a greater number of afferent nociceptive fibers. The suprascapular, axillary, and lateral pectoral nerve articular sensory branches are targeted during CRFA of the glenohumeral joint. The obturator and femoral nerve articular sensory branches are targeted during CRFA of the hip. CRFA is a promising tool in the interventionalist's arsenal for management of OA-related pain and symptoms, particularly in patients who cannot undergo, have long wait times until, or have persistent pain following joint replacement surgery. An invited commentary by Tomasian is available online. ©RSNA, 2022.

Dual-Resonance (16/32 MHz) Piezoelectric Transducer With a Single Electrical Connection for Forward-Viewing Robotic Guidewire.

Peripheral artery disease (PAD) affects more than 200 million people globally. Minimally invasive endovascular procedures can provide relief and salvage limbs while reducing injury rates and recovery times. Unfortunately, when a calcified chronic total occlusion is encountered, ~25% of endovascular procedures fail due to the inability to advance a guidewire using the view provided by fluoroscopy. To enable a sub-millimeter, robotically steerable guidewire to cross these occlusions, a novel single-element, dual-band transducer is developed that provides simultaneous multifrequency, forward-viewing imaging with high penetration depth and high spatial resolution while requiring only a single electrical connection. The design, fabrication, and acoustic characterization of this device are described, and proof-of-concept imaging is demonstrated in an ex vivo porcine artery after integration with a robotically steered guidewire. Measured center frequencies of the developed transducer were 16 and 32 MHz, with -6 dB fractional bandwidths of 73% and 23%, respectively. When imaging a 0.2-mm wire target at a depth of 5 mm, measured -6 dB target widths were 0.498 ± 0.02 and 0.268 ± 0.01 mm for images formed at 16 and 32 MHz, respectively. Measured SNR values were 33.3 and 21.3 dB, respectively. The 3-D images of the ex vivo artery demonstrate high penetration for visualizing vessel morphology at 16 MHz and ability to resolve small features close to the transducer at 32 MHz. Using images acquired simultaneously at both frequencies as part of an integrated forward-viewing, guidewire-based imaging system, an interventionalist could visualize the best path for advancing the guidewire to improve outcomes for patients with PAD.

Standard Radiation Dosimetry Models: What Interventional Radiologists Need to Know.

Thoughtful and accurate dosimetry is critical to obtain the safest and most efficacious yttrium-90 (Y90) radioembolization of primary and secondary liver cancers. Three dosimetry models are currently used in clinical practice, namely, body surface area model, medical internal radiation dose model, and the partition model. The objective of this review is to briefly outline the history behind Y90 dosimetry and the difference between the aforementioned models. When applying these three models to a single case, the differences between them are further demonstrated. Each dosimetry model in clinical practice has its own benefits and limitations. Therefore, it is incumbent upon practicing interventional radiologists to be aware of these differences to optimize treatment outcomes for their patients.

Role of Resin Microsphere Y90 Dosimetry in Predicting Objective Tumor Response, Survival and Treatment Related Toxicity in Surgically Unresectable Colorectal Liver Metastasis: A Retrospective Single Institution Study.

PURPOSE: To Evaluate the correlation between tumor dosimetric parameters with objective tumor response (OR) and overall survival (OS) in patients with surgically unresectable colorectal liver metastasis (CRLM) undergoing resin-based Ytrrium-90 selective internal radiation therapy (Y90 SIRT). MATERIALS AND METHODS: 45 consecutive patients with CRLM underwent resin-based Y90 SIRT in one or both hepatic lobes (66 treated lobes total). Dose volume histograms were created with MIM Sureplan® v.6.9 using post-treatment SPECT/CT. Dosimetry analyses were based on the cumulative volume of the five largest tumors in each treatment session and non-tumoral liver (NTL) dose. Receiver operating characteristic (ROC) curve was used to evaluate tumor dosimetric factors in predicting OR by Response Evaluation Criteria for Solid Tumors at 3 months post-Y90. Additionally, ROC curve was used to evaluate non-tumoral liver dose as a predictor of grade ≥ 3 liver toxicity and radioembolization induced liver disease (REILD) 3 months post Y90. To minimize for potential confounding demographic and clinical factors, univariate and multivariate analysis of survival with mean tumor dose as one of the factors were also performed. Kaplan-Meier estimation was used for OS analysis from initial Y90 SIRT. RESULTS: 26 out of 45 patients had OR with a median OS of 17.2 months versus 6.8 months for patients without OR (p < 0.001). Mean tumor dose (TD) of the five largest tumors was the strongest predictor of OR with an area under the curve of 0.73 (p < 0.001). Minimum TD, and TD to 30%, 50%, and 70% of tumor volume also predicted OR (p's < 0.05). Mean TD ≥ 100 Gy predicted a significantly prolonged median OS of 19 vs. 11 months for those receiving TD < 100 Gy (p = 0.016). On univariate analysis, mean TD < 100 Gy, presence of any genomic mutation, presence of MAPK pathway mutation, bilobar hepatic metastases and diffuse metastatic disease (>10 lesions per liver lobe) were found to be predictors of shorter median OS. On multivariate analysis, mean TD < 100 Gy, presence of any genomic mutation, and diffuse hepatic metastatic disease were found to be independent predictors of shorter OS. Overall, six (13.3%) patients developed grade ≥ 3 liver toxicity post Y90 of whom two (4.4%) patients developed REILD. No dose threshold predicting grade ≥ 3 liver toxicity or REILD was identified. CONCLUSIONS: Mean TD ≥ 100 Gy in patients with unresectable CRLM undergoing resin-based Y90 SIRT predicts OR and prolonged OS.

Predictors of Successful Yttrium-90 Radioembolization Bridging or Downstaging in Patients with Hepatocellular Carcinoma.

Purpose: This study aims to identify clinical and imaging prognosticators associated with the successful bridging or downstaging to liver transplantation (LT) in patients undergoing Yttrium-90 radioembolization (Y90-RE) for hepatocellular carcinoma (HCC). Methods: Retrospectively, patients with Y90-RE naïve HCC who were candidates or potential candidates for LT and underwent Y90-RE were included. Patients were then divided into favorable (maintained or achieved Milan criteria (MC) eligibility) or unfavorable (lost eligibility or unchanged MC ineligibility) cohorts based on changes to their MC eligibility after Y90-RE. Penalized logistic regression analysis was performed to identify the significant baseline prognosticators. Results: Between 2013 and 2018, 135 patients underwent Y90-RE treatment. Among the 59 (42%) patients within MC, LT eligibility was maintained in 49 (83%) and lost in 10 (17%) patients. Within the 76 (56%) patients outside MC, eligibility was achieved in 32 (42%) and unchanged in 44 (58%). Among the 81 (60%) patients with a favorable response, 16 (20%) went on to receive LT. Analysis of the baseline characteristics revealed that lower Albumin-Bilirubin score, lower Child-Pugh class, lower Barcelona Clinic Liver Cancer stage, HCC diagnosis using dynamic contrast-enhanced imaging on CT or MRI, normal/higher albumin levels, decreased severity of tumor burden, left lobe HCC disease, and absence of HBV-associated cirrhosis, baseline abdominal pain, or fatigue were all associated with a higher likelihood of bridging or downstaging to LT eligibility (p's < 0.05). Conclusion: Certain baseline clinical and tumor characteristics are associated with the successful bridging or downstaging of potential LT candidates with HCC undergoing Y90-RE.

Improved Tumor Response in Patients on Metformin Undergoing Yttrium-90 Radioembolization Segmentectomy for Hepatocellular Carcinoma.

PURPOSE: Metformin is associated with improved outcomes after external radiation and chemotherapy but has not been studied for Y-90 radiation segmentectomy (RS). This study evaluates the effect of metformin on tumor response after Y-90 RS in patients with hepatocellular carcinoma (HCC). METHODS AND MATERIALS: A retrospective analysis of patients with HCC who underwent Y-90 RS between 2014-2018 was performed. Comparisons were made between all patients taking and not taking metformin, and diabetic patients taking and not taking metformin. Tumor response was analyzed with logistic regression to compare absolute and percent change in total tumor diameter (TTD) and modified Response Evaluation Criteria in Solid Tumors (mRECIST). Overall survival (OS) was evaluated using Kaplan-Meier estimation and log-rank analysis. RESULTS: A total of 106 patients underwent 112 Y-90 RS, of which 40 were diabetic (38.8%) and 19 (18.4%) were on metformin. At baseline, the two groups of patients on metformin and not on metformin had no significant difference in age, Child-Pugh score, MELD score, ALBI grade, total tumor diameter, and size of dominant tumor. The only significant baseline difference was ECOG status. Uni- and multivariate analysis demonstrated a larger reduction in TTD and objective response by mRECIST criteria for patients undergoing Y-90 RS on metformin compared to those not on metformin. OS was similar between patients taking and not taking metformin (p = 0.912). CONCLUSION: Metformin may be associated with increased tumor response after Y-90 RS in patients with HCC. LEVEL OF EVIDENCE: III, Retrospective Study.

Same day yttrium-90 radioembolization with single photon emission computed tomography/computed tomography: An opportunity to improve care during the COVID-19 pandemic and beyond.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has made it more challenging for patients to undergo yttrium-90 (Y-90) radioembolization (RE). Same day Y-90 RE provides an opportunity to minimize logistical challenges and infection risk associated with COVID-19, thus improving patient access. AIM: To describe the use of same day Y-90 RE with routine single photon emission computed tomography/computed tomography (SPECT/CT) in order to optimize therapy. METHODS: All patients were selected for Y-90 RE through a multidisciplinary tumor board, and were screened and tested for COVID-19 infection per institutional protocol. A same day procedure was developed, consisting of angiography, imaging, and Y-90 resin particle delivery. Routine SPECT/CT after technetium-99m macroaggregated albumin (Tc-99m MAA) administration was performed for assessment of arterial supply, personalized dosimetry, and extrahepatic activity. Post-treatment Y-90 bremsstrahlung SPECT/CT was performed for confirmation of particle delivery, by utilization of energy windowing to limit signal from previously administered Tc-99m MAA particles. RESULTS: A total of 14 patients underwent same day Y-90 RE between March and June 2020. Mean lung shunt fraction was 6.13% (range 3.5%-13.1%). Y-90 RE was performed for a single lesion in 7 patients, while the remaining 7 patients had treatment of multifocal lesions. The largest lesion measured 8.3 cm. All patients tolerated the procedure well and were discharged the same day. CONCLUSION: Same day Y-90 RE with resin-based microspheres is feasible, and provides an opportunity to mitigate infection risk and logistical challenges associated with the COVID-19 pandemic and beyond. We recommend consideration of SPECT/CT, especially among patients with complex malignancies, for the potential to improve outcomes and eligibility of patients to undergo same day Y-90 RE.

Determination of tumour dose response threshold and implication on survival in patients with HCC treated with Y90 radiation segmentectomy: a simple semi-quantitative analysis.

PURPOSE: To evaluate the relationship between Yttrium-90 (Y90) tumour dose and response rate in patients with hepatocellular carcinoma (HCC) who undergo Y90 radiation segmentectomy (Y90-RS) and to determine implication on overall survival (OS). MATERIALS AND METHODS: Post Y90-RS Bremsstrahlung single-photon emission computed tomography/CT of 105 HCC patients with 110 treatments performed with glass microspheres was retrospectively analysed. The dose-volume histogram of the targeted tumour was determined with commercially available dosimetry software. Tumour response at 3 months was evaluated using modified Response Evaluation Criteria in Solid Tumours. Tumour dose thresholds associated with the objective response with 80% specificity were then used to evaluate implication on OS using Kaplan-Meier estimation and log-rank analysis. RESULTS: Tumour dose thresholds to predict objective response with 80% specificity were the following: maximum tumour dose (748 Gy), mean tumour dose (568 Gy), minimum tumour dose of 30% tumour volume (608 Gy), minimum tumour dose of 50% tumour volume (565 Gy), minimum tumour dose of 70% tumour volume (464 Gy) and minimum tumour dose of 100% tumour volume (213 Gy). These parameters all significantly predicted tumour response with areas under the ROC curve of >0.6. Mean tumour dose of ≥250 Gy predicted median OS of 43.67 vs. 17.87 months for others (P = 0.026). Minimum dose ≥180 Gy to 100% of tumour volume predicted median OS of 44.93 vs. 35.87 months for others (P = 0.043). CONCLUSION: In patients with HCC undergoing Y90-RS, mean tumour dose ≥250 Gy and minimum tumour dose of ≥180 Gy to 100% of tumour volume are both significantly correlated with higher objective tumour response and prolonged survival.