Localized intra-arterial delivery of gemcitabine (IAG) may provide advantages in terms of increased tissue concentration and decreased systemic dosing. We hypothesized IAG may result in decreased systemic gemcitabine concentration and associated side effects due to intracellular delivery prior to conversion to gemcitabine’s inactive metabolite, difluorodeoxyuridine (dFdU). Here we report the results of a pharmacokinetics and pharmacodynamics sub-study within the TIGeR-PaC phase 3 clinical trial (NCT03257033). Analyses were performed for 16 participants across 6 TIGeR-PaC study sites; 11 participants received localized IAG and 5 participants received systemic intravenous gemcitabine (IVG). Gemcitabine and dFdU assays were performed on blood samples collected immediately before, during, and after infusion. CA 19 − 9 levels were measured prior to and 2 weeks after IAG treatment. Maximum plasma drug concentration (Cmax) and the area under the drug plasma concentration curve (AUC0−t) were compared between treatment groups. Pearson’s correlation for AUC0−t and the percent change in CA 19 − 9 levels was calculated for the IAG group. IAG resulted in lower gemcitabine Cmax and AUC0−t and higher dFdU Cmax and AUC0−t compared to IVG, consistent with a more rapid conversion of gemcitabine to dFdU with IAG versus IVG. With IAG, there was a significant correlation between increased dFdU levels and a pre- to post-treatment reduction in CA 19 − 9 levels (Pearson’s r = -0.75; P = 0.034). In addition to providing increased local potency, localized IAG, in which gemcitabine is rapidly converted to its inactive metabolite dFdU, may also be beneficial in decreasing gemcitabine-related systemic side effects.

e16463 Background: Intra-arterial delivery of gemcitabine (IAG) targeted to tumors/tissue may provide higher local drug potency. 1 Furthermore, IAG may result in decreased systemic drug concentration and associated side effects due to intracellular delivery prior to conversion to gemcitabine’s inactive metabolite, difluorodeoxyuridine (dFdU). The ongoing TIGeR-PaC phase 3 trial is testing this approach in patients with locally advanced pancreatic cancer. Here we report the results of a 16-patient pharmacokinetics (PK) and pharmacodynamics sub-study within TIGeR-PaC. Methods: PK analyses were performed for a total of 16 participants across 6 TIGeR-PaC study sites; 11 participants received IAG with the RenovoCath dual balloon catheter at 1000 mg/m 2 over 20 minutes and 5 participants received intravenous gemcitabine (IVG) at 1000 mg/m 2 over 30 minutes. Blood was collected at T = -5, 10, 15, 20, 30, 40, 60, and 90 minutes from the onset of infusion for gemcitabine and dFdU assays. Maximum plasma drug concentration (C max ) and the area under the drug plasma concentration curve from time zero to the last measurable concentration (AUC 0-t ) were compared between the two groups. CA 19-9 tumor marker levels were measured prior to treatment and 2 weeks post-procedure. The relationship between AUC 0-t and the percent change in CA 19-9 levels was assessed; 3 patients with normal CA 19-9 baseline values were excluded from the analysis. Results: As previously shown, IAG results in lower gemcitabine C max and AUC 0-t compared to IVG. 2 Additional analyses showed the dFdU C max and AUC 0-t were higher for IAG compared to IVG, consistent with a more rapid conversion of gemcitabine to dFdU with targeted IAG compared to systemic IVG. With IAG administration, there was a direct correlation between increased dFdU levels and a reduction in CA 19-9 levels (Pearson’s r = 0.75; P = 0.034). These results suggest the conversion of gemcitabine to dFdU at the tissue level may provide a surrogate marker for drug response with IAG administration. Conclusions: In this analysis, localized IAG resulted in decreased systemic levels of gemcitabine compared to IVG, along with increased levels of its inactive metabolite dFdU. Thus, in addition to providing increased local potency, the IAG approach, in which gemcitabine is rapidly converted to its inactive metabolite, may be beneficial in decreasing gemcitabine-related systemic side effects. Clinical trial information: NCT03257033. Farsad K, et al. 2024. JVIR 35:1043-48 e3. Novelli P, et al. 2025. J Clin Oncol 43(4_suppl):719. Clinical trial information: NCT03257033 . Effects of treatment mode on mean pharmacokinetic parameters. PK parameter, mean (SE) IAG Group(N=11) IVG Group(N=5) P -value Gemcitabine: C max (mcg/mL) 12.9 (2.42) 14.6 (1.19) 0.535 AUC (hr ⋅ mcg/mL) 4.9 (0.94) 8.8 (0.99) 0.018 dFdU: C max (mcg/mL) 48.3 (5.61) 30.6 (2.20) 0.012 AUC (hr ⋅ mcg/mL) 46.3 (4.59) 37.1 (2.33) 0.097

719 Background: Localized, dual balloon catheter-mediated, intra-arterial delivery of gemcitabine (IAG) targeted to tumors/tissue can provide higher local drug potency (1). Furthermore, IAG may result in a decreased systemic drug concentration and associated side effects. In patients with locally advanced pancreatic cancer (LAPC), this approach is currently being tested in the TIGeR-PaC Phase 3 clinical trial. Herein we report the results of a 19-patient pharmacokinetics (PK) sub-study analysis within TIGeR-PaC. Methods: PK analyses were performed for a total of 19 participants across 6 TIGeR-PaC study sites; 11 participants received IAG with the RenovoCath dual balloon catheter at 1000 mg/m 2 over 20 minutes and 8 participants received intravenous gemcitabine (IVG) (5 at 1000 mg/m 2 , 2 at 800 mg/m 2 , 1 at 500 mg/m 2 ) over 30 minutes. IAG target treatment arteries were either the superior mesenteric artery (SMA) (n=5) or branches of the celiac axis (n=6). At T = -5, 10, 15, 20, 30, 40, 60, and 90 minutes from the onset of infusion, 2 mL of blood was collected in heparinized tubing containing 25 mcg/mL of tetrahydrouridine. Plasma from each sample was frozen and shipped to a reference lab for gemcitabine assays. Maximum plasma drug concentration (C max ) and the area under the drug plasma concentration curve (AUC) based on the terminal phase were compared between the two groups; for these dose-dependent parameters, only participants who received 1000 mg/m 2 gemcitabine (IAG, N=11; IVG, N=5) were included in the comparison analysis. Results: As shown in the table, AUC was significantly lower with IAG (4.99) compared to IVG (9.97) ( P = 0.019). Peak plasma gemcitabine concentrations were also lower with IAG (12.9 mcg/mL) vs. IVG (14.6 mcg/mL) despite a 50% higher drug concentration during IAG vs. IVG (1000 mg/m 2 infused over 20 minutes vs. 30 minutes, respectively). There was no difference in plasma levels between IAG treatment sites (SMA vs. celiac axis). Conclusions: In this analysis, localized, dual-balloon catheter-mediated IAG resulted in decreased systemic levels of gemcitabine compared to IVG. Thus, in addition to providing increased local potency, the IAG approach may also be beneficial in decreasing gemcitabine-related systemic side effects. 1. Farsad K, et al. 2024. JVIR 35:1043-48 e3. Clinical trial information: NCT03257033 . Effects of treatment mode on mean pharmacokinetic parameters for gemcitabine. PK parameter IAG Group(N=11) IVG Group(N=5) C max (mcg/mL), Mean (SE) 12.9 (±2.4) 14.6 (±1.2) AUC (hr ⋅ mcg/mL), Mean (SE) 4.99 (±0.96) 9.97 (±1.9) AUC = area under the curve; C max = maximum serum concentration; IAG = intra-arterial gemcitabine; IVG = intravenous gemcitabine; PK = pharmacokinetic; SE = standard error.

Gastric varices can pose both diagnostic challenges and serious risk of life-threatening hemorrhage in patients with cirrhotic and noncirrhotic portal hypertension. Management requires a multidisciplinary approach, with gastroenterology playing a key role in diagnosis, endoscopic assessment, and initial treatment strategies. Interventional radiology plays a pivotal role in treatment with advanced portal decompression techniques, Together, gastroenterology and Interventional radiology specialties provide an individualized patient tailored approach to optimize diagnostic and treatment strategies in patients with gastric varices. This article offers a descriptive approach to diagnosing and managing GV.

Purpose: Treatment of hypovascular tumors, such as pancreatic adenocarcinoma, is challenging owing to inefficient drug delivery. This report examines the potential mechanism of localized drug delivery via transarterial microperfusion (TAMP) using a proprietary adjustable double-balloon occlusion catheter in a porcine model. Materials and Methods: Adult Yorkshire swine (N = 21) were used in the Institutional Animal Care & Use Committee- approved protocols. The RC-120 catheter (RenovoRx, Los Altos, California) was positioned into visceral, femoral, and pulmonary arteries with infusion of methylene blue dye, gemcitabine, or gold nanoparticles. Transmural delivery was compared under double-balloon occlusion with and without side-branch exclusion, single-balloon occlusion, and intravenous delivery. Intra-arterial pressure and vascular histologic changes were assessed. Results: Infusion with double-balloon occlusion and side-branch exclusion provided increased intra-arterial pressure in the isolated segment and enhanced perivascular infusate penetration with minimal vascular injury. Infusates were predominantly found in the vasa vasorum by electron microscopy. Conclusions: TAMP enhanced transmural passage mediated by localized increase in arterial pressure via vasa vasorum.

AbstractThe presence of portal vein thrombosis (PVT) in the pre-liver transplant patient can significantly impact waitlist, peri- and posttransplant outcomes, morbidity, and mortality. This article describes the pathophysiology of PVT and treatment options in patients with cirrhosis. It defines indications and rationale for placing transjugular intrahepatic portosystemic shunts, emphasizing technical details and risks in patients with nonneoplastic PVT awaiting liver transplantation.

AbstractPercutaneous management of complications of portal hypertension entails reducing portal pressures, controlling varices, and redirecting collateral flow using embolization, obliterative, restorative, recanalization, and shunt creation techniques. Management is based on the clinical status and symptoms and the physiologic and anatomic abnormalities causing portal hypertension. This article briefly describes percutaneous management strategies, their results, and related iatrogenic and physiologic complications.

2521 Background: Delivery barriers due to intratumoral pressure and immunosuppression related to myeloid-derived suppressor cells (MDSC) in liver tumors have created challenges for immunotherapy. TLR9 agonists seem to improve response to ICI. PERIO-01 is a first-in-man trial of PEDD of SD-101 using hepatic arterial infusion (HAI) with ICI in MUM. Methods: PERIO-01 is an open-label phase 1 trial of SD-101 given by HAI in MUM (NCT04935229). The study consists of dose-escalation cohorts of SD-101 alone (Cohort A), with nivolumab (Cohort B), or nivolumab + ipilimumab (Cohort C). SD-101 is delivered over 2 cycles, with 3 weekly doses per cycle. Blood, liver metastasis (LM) and normal liver biopsies are collected for correlative studies. Results: At data cutoff, 33 patients were enrolled, 30 of whom received at least one dose of SD-101, 13 in Cohort A (2, 4, and 8 mg), 15 patients in Cohort B (2 mg and 4 mg) and 2 patients in Cohort C (2 mg). The median age was 63 years of equal gender. Only 3 patients were treatment-naïve and 2 were HLA-A*-02:01+ who received prior tebentafusp. Nine subjects had 4-7 LM and 4 had > 10. The median index LM size was 4.7 cm. Only one patient experienced a grade ≥3 adverse event (AE) related to SD-101, which was increased liver enzymes. All AEs related to cytokine release syndrome have been low-grade with the most common being fever (9), chills (5), and dizziness (4). Treatment resulted in high liver drug levels (median at 2 mg = 1540 ng/g and 8 mg = 2325 ng/g, p = 0.035), with only transient exposure in the periphery ( < 4 hours) and a maximum peak serum level of 554 mg/ml 30 minutes post-infusion. Increases in serum IL-18 and IFNγ were noted, with highest levels at 8 mg. Expansion of natural killer cells were detected in 9 of 10 patients from flow cytometry data peripherally. Monocytic MDSC levels were decreased in 5 of 5 patients on immunofluorescence, and NanoString analysis revealed decreases in ARG-1 and IDO-1 gene levels up to 100 days from initial treatment. Broad immunostimulatory gene expression changes were noted in tumor and normal liver following SD-101, including increases in IFNB1 and IL-9. Using the available samples from 13 patients, 7 of 10 had decrease in ctDNA, with complete clearance in 3, along with circulating tumor cell decreases in 6 of 13. In cohort B at 2 mg, 5 of 6 with available response data have stable disease with a median duration of disease control of 12 weeks (range = 7.5-24) at data cutoff. Conclusions: HAI of SD-101 has been well tolerated and associated with encouraging immunologic activity. Evidence of biologic effects at the lower doses of SD-101 with nivolumab is encouraging and enrollment with escalation continues in Cohorts B and C. Clinical trial information: NCT04935229 .

728 Background: Localized dual-balloon-mediated, intra-arterial delivery of Gemcitabine (IAG) directly into tumors/tissue can lead to higher local drug potency 1 . Furthermore, IAG may lead to decreased systemic drug concentration and associated side effects. In patients with Locally Advanced Pancreatic Cancer (LAPC), this approach is currently being tested in a contemporary Phase III clinical trial, TIGeR-PaC. Herein we report the results of a 10-patient PK analysis sub-study within TIGeR-PaC. Methods: We analyzed a total of 10 subjects from 5 sites who received intra-arterial gemcitabine with the RenovoCath dual balloon catheter at 1000mg/m 2 over 20 minutes. The target treatment artery was either the celiac axis (n=5) or the superior mesenteric artery (n=5). Samples were drawn at T = -5, 10, 15, 20, 30, 40, 60, and 90 minutes from the onset of infusion. At each timepoint, we collected 2mL of blood in heparinized tubing containing 25 mcg/mL of tetrahydrouridine. The blood samples were then centrifuged collect, freeze, and ship the plasma to a reference lab to perform a gemcitabine assay. The PK parameters for a single dose was estimated for C max , AUC, clearance, and distribution volume based on the terminal phase. These values are compared to historical data for intravenous gemcitabine (IVG) infusion at 1000mg/m 2 over 30 minutes 2 . Results: At this time, data has been analyzed for 4 of 8 collected samples. We expect to complete collection and analysis of all 10 samples by November of 2022. We show results available so far; historical values for IVG are given as a reference point. The results suggest that IAG is associated with decreased systemic exposure of gemcitabine compared to IVG. Conclusions: Localized dual-balloon-mediated, intra-arterial delivery of gemcitabine can lead to decreased systemic levels of gemcitabine. This approach increased local potency and may be beneficial in decreasing gemcitabine-related systemic side effects. 1. Farsad K, et al. 04:21 PM Abstract No. 392 . J Vasc Intervent Radiol 2019;30(3):S172. doi:10.1016/j.jvir.2018.12.467. 2. Chow ECY, Zirkelbach JF. Clinical Pharmacology and Biopharmaceutics Review(s) {209604Orig1s000}. FDA: Center for Drug Evaluation and Research. Clinical trial information: NCT03257033 . [Table: see text]

Abstract Transcatheter arterial chemoembolization (TACE) is the standard practice in treating both primary and metastatic liver neoplasms. TACE is a practical, minimally invasive procedure involving the delivery of chemotherapeutic agents into the artery supplying a tumor while simultaneously embolizing its blood supply. This approach can be used for curative and palliative intent across multiple cancer types. Historically, TACE has been instrumental in the treatment algorithms for hepatocellular carcinoma, allowing patients with unresectable disease to be downstaged and to slow disease progression, affording opportunities for transplantation and increased survival. Although benefits of TACE include lower morbidity and mortality versus systemic chemotherapy and surgical approaches, the procedure has risks and complications. Interventional radiologists and physicians involved in the care of these patients should be aware of the associated complications including avoidance and treatment strategies.

TPS773 Background: Prognosis for locally advanced pancreatic cancer (LAPC) remains dismal even with advances in cancer therapy. Beyond systemic therapies, local disease control is important in these patients. Local double balloon mediated delivery of intra-arterial gemcitabine (IAG) was demonstrated to be safe in this patient population in a prior study1. TIGeR-PaC is an ongoing Phase-3 clinical trial comparing the efficacy of this approach compared to standard of care IV gemcitabine/nab-paclitaxel (GN) for patients with LAPC. Methods: The trial is designed with an induction phase of upfront systemic therapy prior to IAG. Patients with LAPC diagnosed within 6 weeks and ECOG 0-1, receive 3 cycles of GN and 1 cycle of radiation. The form of radiation was either IMRT, 50 Gy in 25 fractions, with concomitant capecitabine or SBRT, 33 Gy in 5 fractions (per site preference). Following induction, patients with non-progressive disease were randomized to receive IAG (8 treatments every two weeks for 16 weeks) or continuing therapy with 4 cycles of GN. After the 16 weeks of randomized therapy, the patients with non-progressive disease went on to continue systemic therapy (GN or capecitabine, per investigator’s preference) until disease progression and then followed for survival only. The primary endpoint is overall survival, and the study has an 80% power to detect a hazard ratio of 0.6 between the two arms. As of September 1st, 2022, 189 patients have been enrolled in the trial. In its initial design the trial expected a 35% drop out rate during the induction phase; however, two years into the trial the actual observed dropout rate was 53%. Beyond progression (22%), the key element of dropout rate was AE/SAE during radiation with IMRT/capecitabine (17%) vs. only 6% with SBRT. To increase accrual of randomized patients, the protocol and the statistical plan were modified to restrict the mode of radiation during induction to SBRT only starting December 2021. Since the modification of the protocol, the dropout rate during induction has decreased to 38%. As of this abstract, 43 patients have been randomized following induction with GN and SBRT. The rate of SAE during active treatment is not different between the 2 arms (20% in each arm), and the most common SAE is GI side effects in both arms. The protocol has a pre-planned interim analysis after 26 events, with 23 events at this writing we expect our first interim analysis later this year. 1. Rosemurgy AS, e al: J Pancreat Cancer. 2017;3(1):58-65. doi:10.1089/pancan.2017.0011. Clinical trial information: NCT03257033 .

AbstractEsophageal varices (EV) are observed in patients with cirrhotic and noncirrhotic portal hypertension. Ectopic varices (ECV) occur outside the esophagogastric region, are less common, and often more challenging to diagnose and effectively manage. The absence of an EV source on endoscopy should raise concern for ECV in patients with significant non-arterial bleeding within the abdomen or gastrointestinal tract. Patient clinical factors including cirrhosis, portal vein thrombosis, and prior abdominal or pelvic surgery warrant an approach for identifying a treatable ECV source. This article offers a descriptive approach to diagnosing and managing ECV in patients with portal hypertension.

399 Background: For patients with pancreatic cancer, tumor growth causing obstruction of the bile duct is a common, yet troubling occurrence, leading to potential serious complications including severe infections. A common technique to correct such an occurrence is the placement of a biliary stent. However, a biliary stent can cause a separate series of complications, especially for patients receiving chemotherapy. A current standard of care treatment for locally advanced pancreatic cancer is intravenous (IV) infusion of gemcitabine and nab-paclitaxel, with the prescribing information for these drugs noting that 5% of patients have experienced sepsis, with those having biliary stents potentially becoming fatal. Methods: In an on-going phase III clinical trial comparing standard of care IV gemcitabine and nab-paclitaxel versus intra-arterial delivery of gemcitabine directly to the tumor via a novel dual-occlusion balloon catheter, data from the cohort of 78 patients (total enrolled as of 1 June 2020) were analyzed for the incidence rate of sepsis among patients with and without biliary stents present. Data analyzed were limited to the initial four-month induction phase, in which patients were to receive two cycles of IV gemcitabine and nab-paclitaxel, one cycle of either IMRT or SBRT, and then one more cycle of IV gemcitabine and nab-paclitaxel. Results: Among the 78 patients, 12 had one episode of sepsis for an incidence rate of 15%. Of the 78 patients, 39 had a biliary stent placed and 9 experienced sepsis during induction (23%) compared to 2 patients among the 39 without a biliary stent present (5%; Chi-square = 4.99, p = 0.02). One additional patient with a biliary stent experienced urosepsis due to urinary tract infection, unrelated to the biliary stent. The majority of the septic events occurred after placement of the stent during the first cycle of chemotherapy (5 of 9 patients), with an average of 8.2 days passed after a dose of chemotherapy was infused to the septic event (range: 2 to 20 days). There was no relationship between ANC and the risk of sepsis. Among other covariates analyzed, age, gender, BMI, and a history of diabetes were not factors shown to affect the likelihood of a septic event. Among the 9 patients who had a septic event with a biliary stent, 2 were fatal, and 3 were withdrawn from the study due to complications from the septic event. Conclusions: These data suggest while the placement of a biliary stent may alleviate certain complications with biliary obstruction, combined with the immunosuppressive qualities of chemotherapy, the likelihood of sepsis increases, with incidence rates significantly greater than those previously reported in the drugs’ prescribing information or previous studies. The current practice of the insertion of the biliary stent potentially introduces flora during the procedure, resulting in potential infection later with administration of chemotherapy. Clinical trial information: NCT03257033.

381 Background: There is no established treatment for locally advanced pancreatic cancer (LAPC), but by utilizing the regimens approved for metastatic pancreatic cancer, hope remains for rendering tumors resectable with chemotherapy. In this context, we looked at the resection rate in patients receiving gemcitabine plus nab-paclitaxel (Gem-Nab) in a prospective trial of patients with LAPC. Methods: TIGeR-PaC is an ongoing phase III clinical trial, studying the role of intra-arterial Gemcitabine (IA-Gem) in LAPC. The trial is designed with an induction phase where patients receive 3 cycles of Gem-Nab and a cycle of radiation after which they are randomized to IA-Gem or continuing with 4 cycles of Gem-Nab. We studied the resection rate in patients receiving Gem-Nab during induction who had subsequently continued receiving Gem-Nab post-randomization. Results: As of July 2020, 80 patients have been enrolled in the study. From this report, 30 patients were excluded because they had not completed induction and/or active treatment or were randomized to IA-Gem at the time of analysis. From the remaining 50 patients, 5 underwent resection for an overall resection rate of 10%. The median age for the total cohort was 67 years (range 47-83). Most of the resections were performed on the younger cohort of patients under 65 years (median age 60, range 47-65) in whom the resection rate was 4 out of 22 (18.2%). Conclusions: In the younger cohort of patients, TIGeR-PaC results are in line with the 15% resection rate in the LAPACT trial of patients with median age of 65 years, as reported by Phillip et al., 2020. In the TIGeR-PaC study the resection rate for LAPC treated with Gem-Nab was 10% overall, and 18.2% for younger patient population. These resection rates are comparable to the other reports for Gem-Nab and are similar to retrospective reports for the younger patients undergoing resection after treatment with FOLFIRINOX. Clinical trial information: NCT03257033.

Purpose: To evaluate the safety and efficacy of percutaneous nephrostomy (PCN) in pregnancy. Materials and methods: PCN tubes were placed during 52 pregnancies in 49 patients from 2008 to 2018. The medical records during pregnancies were retrospectively reviewed for imaging findings, procedural parameters, outcomes of delivery, and complications. Results: The mean gestational age on percutaneous nephrostomy placement was 27 weeks (range, 8-36 weeks). PCN catheters were placed for the following indications: 1) flank or lower abdominal pain (42%), 2) obstructing calculi (37%), 3) pyelonephritis (20%), and 4) obstructing endometrioma (2%). Prior to PCN, retrograde ureteric stenting was performed in 17 of 49 patients (34%) and attempted but failed in 4 patients (8%). Nephrostomy drainage relieved pain completely or significantly in all 12 patients without prior ureteral stenting, but in only 4 of 10 with retrograde ureteric stents. In one patient in whom the ureteral stent had been removed, PCN relieved her flank pain. The mean number of PCN catheter exchanges was 1.6, ranging from 0 to 9, with a mean time interval of 21.3 days between exchanges. There were 29 difficult exchanges due to encrustation in 15 patients with a mean of 20.5 days between exchanges. Conclusions: PCN drainage is a safe and effective treatment for managing symptomatic hydronephrosis in pregnant patients but is less effective in treating pain when retrograde ureteral stents are in place. Rapid encrustation, seen more commonly in pregnancy, tends to recur in the same patients and requires more frequent exchanges than the general population.

Each year approximately 8500 patients undergo liver transplantation in the USA for acute and chronic liver failure. Over the years, the success of liver transplantation has led to more clinical indications for liver transplantation. These expanded indications, without a proportionate increase in donors, result in increased competition for the limited pool of transplantable whole or partial grafts. The likelihood of receiving a deceased donor graft depends on many clinical variables, including the acute and chronic fitness of the candidate aligning with the timing of donor organ availability. Several types of patients are candidates for transplant: patients with acute fulminant hepatic failure who will die without a transplant, patients with decompensated cirrhosis, and patients with HCC and compensated cirrhosis. Interventional radiology can preserve equity between these subgroups and reduce patient dropout by increasing the physiologic and anatomic fitness of the candidate before and after formal listing. The primary determinants of candidacy fitness and dropout are the severity of clinical symptoms related to portal hypertension and the presence of hepatocellular cancer. There is a subgroup of patients whose disease severity is not accurately reflected by the Model for End-stage Liver Disease (MELD), such as patients with chronic cholestasis that also may benefit from IR management.

e16119 Background: Assessment of the clinical outcomes and prognostic value of genomic mutations in colorectal liver metastases treated with Y90 radioembolization. Methods: Multi-institution retrospective study of patients who underwent Y-90 radioembolization treatment after tumor genotyping was completed for CRLM. Patients treated between 2008 and 2019 were included from 7 institutions within the United States and Europe. Patient demographics, tumor characteristics, pre- and post- treatment regimens, serum laboratory evaluation and overall survival were analyzed between patients with differing histopathologic and genomic status. Tumor genotyping was obtained for KRAS, BRAF, PIK3CA, AKT, MEK, NRAS and MMR genes. Kaplan-Meier survival estimation and multivariate Cox regression were analyzed. Results: 434 patients treated with Y90 radioembolization fulfilled the inclusion criteria. Of the total cohort, 399 patients were available who had sufficient documented tumor profiling data. Average age at diagnosis was found to be 58.8 years for all patients (60.1% male, 39.9% female). Decreased survival post Y-90 treatment was shown in those patients with increased number of documented tumor mutations (n = 0,1 or ≥2 mutations: median OS 9.63 mos vs. 6.2 mos vs. 5.3 mos; p < 0.0001). Additionally, the median survival in patients with mutated BRAF was 5.0 months, as compared to 9.4 months in those patients with wild-type BRAF (p = 0.0009). Primary colon cancer sidedness was also shown to demonstrate significant difference in survival post-Y90 treatment with left sided primaries showing improved median overall survival (left = 7.5 mos vs. right = 6.3 mos; p = 0.04.) Patient demographics including gender, age and race were not shown to be significant in overall survival post-Y90 treatment (p-values > 0.05). Number of tumor mutations (p < 0.0001, HR = 1.69 CI: 1.39-2.05), BRAF status (p = 0.02, HR = 2.6 CI:1.20-4.9), primary sidedness (p = 0.01, HR = 0.65 CI:0.47-0.90), pre-treatment neutrophil-lymphocyte ratio (p = 0.04, HR = 1.42 CI: 1.02-1.98) and KRAS mutation status (p < 0.0001, HR = 1.81 CI: 1.45-2.26) all persisted as significant predictors of survival on multivariate analysis. Conclusions: Number of tumor mutations, BRAF mutation status, primary tumor sidedness, neutrophil-lymphocyte ratio and KRAS mutation status are all shown to be significant prognostic factors in patients with colorectal liver metastases receiving Y90 radioembolization.

Injury to the thoracic duct with resultant chylothorax can cause significant patient morbidity and mortality. Conservative treatment strategies often fail to address the problem. Open surgical and percutaneous approaches are often required to manage patients with refractory chylothorax. This review describes in detail the major role of minimally invasive interventional therapies for thoracic duct (TD) injury. The review emphasizes strategies for identifying the TD on preprocedural imaging and describes various techniques for percutaneous access to the TD. The advantages and disadvantages of several approaches for accessing the duct are discussed. The technique of duct embolization is highlighted. The role of the minimally invasive percutaneous approach over open surgical approaches is discussed with a review of clinical outcomes, as reported in the literature. This review will also briefly discuss the surgical approach to TD ligation.

Purpose: In 90Y microsphere radioembolization (RE), accurate post‐therapy imaging‐based dosimetry is important for establishing absorbed dose versus outcome relationships for developing future treatment planning strategies. Additionally, accurately assessing microsphere distributions is important because of concerns for unexpected activity deposition outside the liver. Quantitative 90Y imaging by either SPECT or PET is challenging. In 90Y SPECT model based methods are necessary for scatter correction because energy window‐based methods are not feasible with the continuous bremsstrahlung energy spectrum. The objective of this work was to implement and evaluate a scatter estimation method for accurate 90Y bremsstrahlung SPECT/CT imaging. Methods: Since a fully Monte Carlo (MC) approach to 90Y SPECT reconstruction is computationally very demanding, in the present study the scatter estimate generated by a MC simulator was combined with an analytical projector in the 3D OS‐EM reconstruction model. A single window (105 to 195‐keV) was used for both the acquisition and the projector modeling. A liver/lung torso phantom with intrahepatic lesions and low‐uptake extrahepatic objects was imaged to evaluate SPECT/CT reconstruction without and with scatter correction. Clinical application was demonstrated by applying the reconstruction approach to five patients treated with RE to determine lesion and normal liver activity concentrations using a (liver) relative calibration. Results: There was convergence of the scatter estimate after just two updates, greatly reducing computational requirements. In the phantom study, compared with reconstruction without scatter correction, with MC scatter modeling there was substantial improvement in activity recovery in intrahepatic lesions (from > 55% to > 86%), normal liver (from 113% to 104%), and lungs (from 227% to 104%) with only a small degradation in noise (13% vs. 17%). Similarly, with scatter modeling contrast improved substantially both visually and in terms of a detectability index, which was especially relevant for the low uptake extrahepatic objects. The trends observed for the phantom were also seen in the patient studies where lesion activity concentrations and lesion‐to‐liver concentration ratios were lower for SPECT without scatter correction compared with reconstruction with just two MC scatter updates: in eleven lesions the mean uptake was 4.9 vs. 7.1 MBq/mL (P = 0.0547), the mean normal liver uptake was 1.6 vs. 1.5 MBq/mL (P = 0.056) and the mean lesion‐to‐liver uptake ratio was 2.7 vs. 4.3 (P = 0.0402) for reconstruction without and with scatter correction respectively. Conclusions: Quantitative accuracy of 90Y bremsstrahlung imaging can be substantially improved with MC scatter modeling without significant degradation in image noise or intensive computational requirements.