Transarterial Radioembolization for Management of Hepatocellular Carcinoma.

Transarterial radioembolization (TARE) with Yttrium-90 (Y90) is a growing area of study due to its benefits in early-, intermediate-, and late-stage hepatocellular carcinoma. Treatment intent, including curative therapy, bridging to transplant, and downstaging disease, informs treatment approach and dosimetry goals. Radiation lobectomy (RL) and radiation segmentectomy (RS) are the 2 main forms of Y90 administration which have shown improved survival outcomes with the development of personalized dosimetry. RS aims to achieve complete pathological necrosis with dose escalation and RL aims for local disease control as well as induction of contralateral lobe hypertrophy to improve hepatic reserve. Furthermore, TARE has been validated in head-to-head comparison to other locoregional and systemic therapies. Lastly, early potential exists for combination therapy between TARE and immune checkpoint inhibitors for advanced stage disease.

Measurement of the Tumor-to-Normal Ratio for Radioembolization of Hepatocellular Carcinoma: A Prospective Study Comparing 2-Dimensional Perfusion Angiography, Technetium-99m Macroaggregated Albumin, and Yttrium-90 SPECT/CT.

PURPOSE: To calculate the preradioembolic tumor-to-normal (T:N) ratio in hepatocellular carcinoma (HCC) using 2-dimensional (2D) perfusion angiography and compare it with that calculated using technetium-99m macroaggregated albumin (99mTc MAA) single-photon emission computed tomography (SPECT)/computed tomography (CT). MATERIALS AND METHODS: This prospective single-arm study enrolled 15 participants with HCC who underwent 2D perfusion angiography immediately before the enrollment and with the microcatheter located at the same location as 99mTc MAA injection, after which SPECT/CT was performed. Quantitative digital subtraction angiography was used to calculate the area under the curve for the tumor and normal hepatic parenchyma and subsequently calculate the T:N ratio. The T:N ratio was calculated from the 99mTc MAA SPECT/CT and post-yttrium-90 bremsstrahlung SPECT/CT using dosimetry software. RESULTS: The mean participant age was 64.1 years ± 9.8, and the study included 14 (93%) men and 1 (7%) woman. The mean tumor size was 4.1 cm (SD ± 2.4), and all participants received segmental treatments with glass microspheres. The mean T:N ratio calculated by 99mTc MAA SPECT/CT was 2.28 (SD ± 0.89) vs 2.25 (SD ± 0.99) calculated by 2D perfusion angiography (P = .45). For the 13 participants who underwent selective internal radiation therapy (transarterial radioembolization), there was no significant difference between the T:N ratios calculated by 2D perfusion angiography and post-90Y SPECT/CT (2.25 [SD ± 1.05] vs 1.91 [SD ± 0.39]; P = .12). CONCLUSIONS: The T:N ratio calculated by 2D perfusion angiography correlated well with that calculated by 99mTc MAA SPECT/CT.

Modified Radiation Lobectomy Strategy of Radioembolization for Right-Sided Unresectable Primary Liver Tumors.

PURPOSE: To assess the safety and effectiveness of using modified radiation lobectomy (mRL) to treat primary hepatic tumors located in the right hepatic lobe (Segments V-VIII) and to determine future liver remnant (FLR) hypertrophy. MATERIALS AND METHODS: A retrospective review was performed at a single institution to include 19 consecutive patients (7 females, 12 males) who underwent single-session mRL for right-sided primary hepatic tumors: 15 received segmentectomy plus lobectomy (segmental dose of >190 Gy and lobar dose of >80 Gy); 4 were treated with the double-segmental approach (dominant segments of >190 Gy and nondominant segments of >80 Gy). Treated tumors included 13 hepatocellular carcinoma (HCC), 4 cholangiocarcinoma (CCA), and 2 mixed-type HCC-CCA with a median dominant tumor size of 5.3 cm (interquartile range [IQR], 3.7-7.3 cm). FLR of the left hepatic lobe was measured at baseline, T1 (4-8 weeks), T2 (2-4 months), T3 (4-6 months), and T4 (9-12 months). RESULTS: Objective tumor response and tumor control were achieved in 17 of the 19 (89.5%) and 18 of the 19 (94.7%) patients, respectively. FLR hypertrophy was observed at T1 (median, 47.8%; P = .025), T2 (median, 48.4%; P = .012), T3 (median, 50.4%; P = .015), and T4 (median, 59.1%; P < .001). Patients without cirrhosis demonstrated greater hypertrophy by 6 months (median, 55.8% vs 47.2%; P = .031). One patient developed a Grade 3 adverse event (ascites requiring paracentesis) at 1-month follow-up. Grade ≥2 serum toxicities were associated with worse baseline Child-Pugh Score, serum albumin, and total bilirubin (P < .05). Among 7 patients who underwent neoadjuvant mRL, 2 underwent resection and 1 received liver transplant. CONCLUSIONS: mRL appears safe and effective for treatment of right-sided primary hepatic tumors with the benefit of promoting FLR hypertrophy.

Tumor Size and Watershed Area Correlate with Incomplete Treatment and Tumor Progression after Selective Radioembolization for Hepatocellular Carcinoma.

PURPOSE: To identify factors of incomplete treatment after segmental transarterial radioembolization (TARE) for treatment-naive and solitary hepatocellular carcinoma (HCC). MATERIALS AND METHODS: A total of 75 consecutive patients (age, 68.5 years [SD ± 8.0]; 25/75 [33.3%] women) with treatment-naive, solitary HCC underwent segmental or subsegmental TARE with glass microspheres (tumor size, 3.8 cm [SD ± 2.2]; administered dose, 222.6 Gy [SD ± 123.9]) at a single institution from November 2015 to June 2022. Radiologic response and progression-free survival (PFS) were assessed as per modified Response Evaluation Criteria in Solid Tumors. RESULTS: Complete treatment was achieved in 48 of 75 (64.0%) patients (mean follow-up, 33.2 months [SD ± 27.4]). Patients with incomplete treatment (27/75, 36%) presented with larger tumor size (5.0 [SD ± 2.5] vs 3.1 [SD ± 1.6] cm; P = .0001), with more tumors located in the watershed zone (81.5% vs 41.7%; P = .001). These patients were less likely to be bridged to transplant or resection (22.2% vs 52.1%; P = .015). Watershed tumors demonstrated worse target tumor PFS (median PFS, 19 months vs not reached; P = .0104) and overall PFS (9.1 months vs not reached; P = .0077). Watershed location was associated with worse PFS among tumors >3 cm in size (8.4 months vs not reached; P = .035) but not in tumors ≤3 cm in size (52.2 months vs not reached; P = .915). CONCLUSIONS: Tumor size and watershed location were associated with incomplete treatment after segmental TARE for HCC. Watershed tumors were associated with worse PFS, particularly tumors larger than 3 cm. These tumors may require careful treatment planning and repeated treatments to ensure a durable response.

Yttrium-90 Radioembolization and Concomitant Systemic Gemcitabine, Cisplatin, and Capecitabine as the First-Line Therapy for Locally Advanced Intrahepatic Cholangiocarcinoma.

PURPOSE: To determine the safety and effectiveness of yttrium-90 transarterial radioembolization (TARE) combined with systemic gemcitabine, cisplatin, and capecitabine for the first-line treatment of locally advanced intrahepatic cholangiocarcinoma (iCCA). MATERIALS AND METHODS: Data of 13 patients with treatment-naïve, locally advanced iCCA treated with a downstaging protocol using gemcitabine, cisplatin, TARE, and capecitabine were retrospectively reviewed. Overall survival (OS), local tumor response (modified Response Evaluation Criteria in Solid Tumors), progression-free survival (PFS), technical adverse events, and toxicity were measured. RESULTS: Calculated from the time of diagnosis, the median OS was 29 months (95% confidence interval [CI], 15 to not reached), with a 1-year OS of 84.6% (95% CI, 52.2%-95.9%) and 2-year OS of 52.9% (95% CI, 20.3%-77.5%). The median OS values were 24 months (95% CI, 8 to not reached) and 21 months (95% CI, 5 to not reached) from the time of initial cycle of chemotherapy and TARE, respectively. Patients who were downstaged to surgery (n = 7, 53.8%) had a more favorable OS (median OS, not reached vs 15 months; P = .0221). Complete and partial radiologic responses were achieved in 5 (38.5%) and 6 (46.2%) patients, respectively. The median PFS was 13 months (95% CI, 12 to not reached). Although no serum toxicity with Grade >2 occurred within 3 months after TARE, 1 patient was no longer a surgical candidate given suboptimal nutrition status despite successful downstage on imaging studies. Two patients required a reduced dose or delay of post-TARE chemotherapy. CONCLUSIONS: First-line combination therapy with TARE and systemic gemcitabine, cisplatin, and capecitabine is an effective treatment with an acceptable safety profile for iCCA with a high rate of downstaging to resection.

Segmental Yttrium-90 Radioembolization Using Glass Microspheres Greater than 400 Gray for the Treatment of Intrahepatic Cholangiocarcinoma: A Preliminary Experience.

Radiation segmentectomy with a dose of >190 Gy using yttrium-90 (90Y) glass microspheres for intrahepatic cholangiocarcinoma (iCCA) has been shown to be safe and effective. The present study further increased the dose to >400 Gy for treatment of iCCA as complete pathologic necrosis has been shown in hepatocellular carcinoma using this ablative approach. A total of 10 patients with 13 tumors (median size, 5.3 cm; range, 1.5-13.6 cm) at a single institution underwent >400-Gy segmental radioembolization. Objective response was achieved in all tumors (13 of 13, 100%). One patient developed a Grade 3 or greater major adverse event (stroke and hepatic decompensation). One patient was bridged to transplant (>95% pathologic necrosis), whereas another underwent resection (>99% necrosis). Contralateral hypertrophy was observed in 6 out of 6 patients treated with modified lobectomy dosing, with a functional liver reserve increase from a median of 31.5% to 57.1%. The present report suggests that segmental transarterial radioembolization with >400 Gy is feasible in terms of safety and effectiveness for treating iCCA.

Clinical and Dosimetric Implications of Calculating Lung Shunt Fraction for Hepatic 90Y Radioembolization Using SPECT/CT Versus Planar Scintigraphy.

BACKGROUND. Accurate assessment of hepatopulmonary shunting, typically performed by planar scintigraphy, is critical in planning 90Y radioembolization. High lung shunt fractions (LSFs) may alter treatment. OBJECTIVE. The purpose of this study is to compare LSFs calculated from planar scintigraphy versus SPECT/CT in patients with high planar LSFs (> 15%) and to describe the potential clinical and dosimetric implications of SPECT/CT LSF calculations. METHODS. This retrospective study included 36 patients (29 men and seven women; mean age, 62.4 ± 9.8 [SD] years) who underwent 99mTc-macroaggregated albumin (MAA) planar scintigraphy for planning hepatic radioembolization, had a planar LSF greater than 15%, and underwent concurrent SPECT/CT. Clinically reported planar LSFs were recorded. SPECT/CT LSFs were retrospectively calculated using automatically generated volumetric ROIs around the lungs and liver with subsequent manual adjustments. Total lung and perfused liver doses were calculated using a medical internal radiation dose model. Values derived from planar and SPECT/CT data were compared using Mann-Whitney U tests. Multivariable regression analysis was performed of factors associated with the discrepancy in LSF between the techniques. RESULTS. Mean planar LSF was 25.1% ± 11.6%, and mean SPECT/CT LSF was 16.0% ± 9.3% (p < .001). Mean lung dose was 18.8 ± 8.0 Gy for planar LSF versus 12.3 ± 7.2 Gy for SPECT/CT LSF (p < .001). Mean perfused liver dose was 92.9 ± 36.1 Gy using planar LSF versus 102.7 ± 39.1 Gy using SPECT/CT LSF (p < .001). In multivariable analysis, a larger discrepancy in LSF between planar scintigraphy and SPECT/CT was associated with a body mass index (weight in kilograms divided by the square of height in meters) of 26 or higher (p = .02), maximum tumor size of less than 9 cm (p = .05), and left hepatic intraarterial injection (p = .02). Fourteen of 36 patients did not undergo upfront radioembolization due to a planar LSF greater than 20% and instead underwent shunt-reducing embolization with subsequent radioembolization (n = 7), transarterial chemoembolization (n = 5), or no treatment (n = 2). Five of these 14 patients had a SPECT/CT LSF of less than 20% and would have been eligible for upfront radioembolization based on SPECT/CT LSF. Seven of 29 patients treated with radioembolization underwent prescribed dose reductions based on planar LSF; six of these patients would have qualified for standard radioembolization without dose reduction using SPECT/CT LSF. CONCLUSION. Planar scintigraphy yields greater LSFs compared with SPECT/CT, possibly leading to unnecessary shunt-reducing procedures and prescribed dose reductions. CLINICAL IMPACT. SPECT/CT should be considered for clinical LSF calculations before radioembolization in patients with high LSFs.

Quantitative Assessment of the Hemodynamic Effects of Intra-Arterial Nitroglycerin on Hepatocellular Carcinoma using Two-Dimensional Perfusion Angiography.

PURPOSE: To determine the hemodynamic effects of intra-arterial nitroglycerin on hepatocellular carcinoma (HCC) using 2-dimensional (2D) perfusion angiography. MATERIALS AND METHODS: Two-dimensional perfusion angiograms obtained prior to radioembolization from September 2019 to February 2020 were retrospectively reviewed. The inclusion criteria were the presence of Liver Imaging Reporting and Data System-5 tumors and angiographically distinguishable tumor and background liver. The exclusion criteria were previously treated tumors and motion-degraded studies. Thirteen patients with 2D perfusion angiograms obtained before and 2 minutes ± 1 after the administration of intra-arterial nitroglycerin were analyzed. The mean patient age was 72 years ± 9 and 11 of 13 (85%) had cirrhosis. The mean maximum tumor dimension was 4.6 cm ± 2.1. Eight tumors were in the right lobe and 5 were in the left lobe. The tumor and background liver 2D perfusion data were processed and the areas under the time-density curves were calculated. The relative perfusion of HCC to background liver was compared before and after nitroglycerin administration using a 2-tailed paired t-test. RESULTS: The mean rate of contrast administration was 1.4 mL/s ± 0.7 and the mean volume administered was 7.1 mL ± 3.3. The mean nitroglycerin dose was 281 µg ± 69. Ten of 13 patients (77%) demonstrated a relative increase in tumor perfusion. The mean HCC to background liver area under the curve ratio was 1.94 ± 0.76 before and 2.40 ± 0.89 after nitroglycerin administration (P < .05). CONCLUSIONS: Intra-arterial nitroglycerin increases previously untreated HCC perfusion relative to background liver as measured by 2D perfusion angiography, but this effect is variable among patients and should be validated with 3-dimensional imaging techniques.

Efficacy and Safety of Mechanical IVC Filtration for Preventing Pulmonary Embolism in High-Risk Orthopedic Patients Undergoing Total Hip or Knee Arthroplasty.

BACKGROUND: To determine the efficacy and safety of inferior vena cava (IVC) filters in preventing pulmonary embolism (PE) in high-risk patients undergoing hip or knee arthroplasty. METHODS: 2857 hip or knee arthroplasty procedures between January 2013 and December 2018 were retrospectively reviewed. Patients with a preoperative history of venous thromboembolism (VTE), either PE or deep venous thrombosis (DVT), were categorized as high-risk patients. The incidence of overall VTE, PE, and DVT were compared between patients with filters and those without. The subgroup analysis was also performed by patient risk, and filter status and the incidence of VTE, PE, and DVT were compared. Variables such as filter placement, history of hypercoagulability etcetra were evaluated as risk factors for the development of postoperative VTE. RESULTS: In the high-risk group, the use of IVC filters was significantly associated with a lower incidence of pulmonary embolism (0.8% vs 5.5%, P = .028). When compared with the low-risk group, the high-risk group had significantly higher incidence of PE (3.8% vs 2.0%, P = .038), DVT (11.6% vs 5.3%, P < .001), and overall VTE (15.0% vs 6.8%, P < .001). The history of VTE was associated with postoperative VTE (P < .001), PE (P = .042), and DVT (P < .001). There was no significant correlation between filter placement and postoperative VTE, DVT, or PE in the low-risk group. Filter retrieval was successful in 100% (96/96) of attempted patients with no complications. CONCLUSION: The use of IVC filters is significantly associated with a lower incidence in pulmonary embolism in high-risk arthroplasty patients. High-risk patients demonstrated an incidence of postoperative VTE over two times greater than other patients. Prophylactic placement of IVC filters in hip/knee arthroplasty is safe.

Same-Day Repeat Hepatopulmonary Shunt Measurement during Planning Angiography for Hepatic Radioembolization.

This report describes a technique for measuring lung shunt fraction (LSF) twice in a single session during planning arteriography for radioembolization using low and standard dose technetium-99m macroaggregated albumin (99mTc-MAA). A patient with a 16.0 cm hepatocellular carcinoma and LSF of 70% was treated with lenvatinib for 4 weeks. Planning arteriography with administration of 0.5 millicuries of 99mTc-MAA was then performed. Arterial access was maintained while the LSF was calculated, which was persistently elevated at 54%. Embolization of arteriovenous shunts was performed during the same session and 5.0 millicuries of 99mTc-MAA were administered. The repeat LSF was 29%. Successful radioembolization was subsequently performed.

Gallbladder Cryoablation for Chronic Cholecystitis in High-Risk Surgical Patients: 1-Year Clinical Experience with Imaging Follow-up.

PURPOSE: To assess the short-term safety and efficacy of gallbladder cryoablation in high-risk patients. MATERIALS AND METHODS: A single-center, retrospective review of clinical and imaging follow-up from patients who were referred for gallbladder cryoablation between August 2018 and July 2019 was performed. All patients had serious pre-procedural comorbidities and were unacceptable surgical candidates (mean age, 52.5 years; mean American Society of Anesthesiologists score, 3.67). Primary efficacy measures included technical success, absence of symptoms after cholecystostomy tube removal, and imaging evidence of cystic duct obstruction and gallbladder involution. The primary safety measure was the absence of Society of Interventional Radiology moderate or greater adverse events. RESULTS: Technical success was 86%, with 1 of 7 patients unable to undergo cryoablation because of adhesions preventing hydrodissection of the colon away from the gallbladder. Mean duration of clinical follow-up after discharge was 278 days (range, 59-498 days). Abdominal pain was absent in all patients after ablation. Cholecystostomy tubes were removed immediately after ablation (n = 5) or on post-procedure day 11 (n = 1). Computed tomography or magnetic resonance imaging was obtained at 1-3 months (n = 6), 4-6 months (n = 4), and 6-12 months (n = 5) after the procedure and demonstrated gallbladder involution in 5 of 6 patients. One patient had asymptomatic distention of the gallbladder on follow-up imaging. Hepatobiliary iminodiacetic acid scans were completed in 5 of 6 patients 1 month after ablation and demonstrated cystic duct occlusion in all 5 patients. One moderate adverse event (infection) and 1 life-threatening adverse event (hemorrhage) occurred. CONCLUSIONS: Gallbladder cryoablation might be a viable treatment option for high-risk patients with gallbladder disease and warrants further investigation.

A Single-Institutional Comparative Analysis of Advanced Versus Standard Snare Removal of Inferior Vena Cava Filters.

PURPOSE: To investigate differences in procedure time, radiation exposure, and periprocedural complications associated with advanced inferior vena cava (IVC) filter retrieval compared with standard snare retrieval. MATERIALS AND METHODS: A total of 378 patients underwent standard or advanced IVC filter retrieval over a 5-year period. Technical success, retrieval techniques, fluoroscopy time, radiation dose, and complications were analyzed. All retrieval procedures with techniques other than a "snare-and-sheath" method were categorized as advanced, including failed standard attempts requiring intraprocedural conversion to advanced techniques. RESULTS: A total of 462 filter retrieval attempts were made in 378 patients (57% female). Success rates for standard and advanced retrieval attempts were 86.8% (317 of 365) and 91.8% (89 of 97), respectively. The rate of periprocedural complications was significantly higher in the advanced retrieval group (P = .006). Complication rates for standard and advanced retrievals were 0.6% (2 of 318; all minor) and 5.2% (5 of 97; 3 minor [3.1%] and 2 major [2.1%]), respectively. The 2 major complications during advanced retrievals included filter fracture and embolization. Average fluoroscopy time for advanced retrievals was significantly higher than for standard retrievals (23.1 min vs 4.3 min; P < .001). Average radiation dose for advanced retrievals was also significantly higher than for standard retrievals (557.2 mGy vs 156.9 mGy; P < .001). Use of general anesthesia was also significantly more common in advanced retrievals compared with standard retrievals (6.2% vs 0.9%; P = .002). CONCLUSIONS: Advanced filter retrieval results in a similarly high rate of technical success compared with standard snare retrieval but is associated with greater fluoroscopy time, anesthesia requirements, and radiation exposure.

Inability of conventional imaging findings to predict response to laparoscopic release of the median arcuate ligament in patients with celiac artery compression.

OBJECTIVE: The objective of this study was to identify duplex ultrasound (DUS) or computed tomography angiography (CTA) imaging findings that can predict clinical response to laparoscopic release of the median arcuate ligament (MAL) in patients with celiac artery compression. METHODS: There were 299 patients who were evaluated for MAL syndrome (MALS) between January 2009 and November 2015. Of these, 29 underwent laparoscopic MAL release and completed 1-year follow-up. The patients' preoperative and postoperative symptoms, use of analgesics, and body mass index were recorded. Patients' demographics and DUS and CTA findings were reviewed. Fisher exact and Student t-tests were used to identify correlation between patient or imaging variables and clinical outcomes. RESULTS: There were 19 patients (66%) who reported improvement in symptoms, and 18 (62%) decreased their use of analgesics; average body mass index increased by 0.2 (standard deviation, 1.97; range, -3.35 to 5.11). No celiac artery DUS finding (peak celiac artery velocity, angle of deflection, or change in preoperative to postoperative velocity) was predictive of successful clinical outcomes (P > .05). Similarly, no CTA finding (characteristic morphology, cross-sectional area, diameter, or location of the focal stenosis of the celiac artery) was associated with clinical outcomes (P > .05). CONCLUSIONS: Clinical response to laparoscopic MAL release was favorable in two-thirds of patients; however, no specific imaging finding of stenosis was predictive of this response. Given that the severity of stenosis on conventional imaging had no impact on treatment efficacy, vascular compromise may not be the primary cause of pain in patients presenting with this syndrome. Future investigation incorporating the neurogenic basis of MALS pain, such as with diagnostic celiac ganglion blockade, would be helpful in further elucidating the enigmatic pathophysiologic process of MALS.

Medical industry at tumor board: Three-years analysis of the open payments database and comparison of oncologic specialties.

BACKGROUND AND OBJECTIVES: To analyze and contrast medical industry payments across U.S. oncologic providers, including hematology-oncology (HO), surgical oncology (SO), interventional radiology (IR), and radiation oncology (RO). METHODS: Open-payment-data for each provider including provider specialty, state of practice, industry payor, reason for payment, and amount was compiled for each transaction between 2013 and 2015. Total, mean, and median payment amounts per-provider were calculated for each specialty. Tukey's-method was used to identify and remove statistical outliers and Kruskal-Wallis-test with Bonferonni-post-hoc-analysis was used to evaluate for differences in total payments received per-provider across specialties. The percentage of providers accepting payments within each specialty were compared by Marascuilo's multiple-proportion-comparison. RESULTS: Total aggregate payment amount (and number of transactions) for HO, SO, IR, and RO was $164 743 746 (778 007), $7 925 467 (15 031), $49 817 380 (44 939), and $13 643 739 (49 778), respectively. Corrected-median (and corrected-mean) payments-per-specialty were $676 ($1796), $330 ($1209), $487 ($1301), and $242 ($766). A significantly higher proportion of HO providers accepted payments than both RO (97% vs 80%, P < 0.0001) and IR (97% vs 78%, P < 0.0001). The mean total payment received per-provider differed significantly across specialties (P = 0.0001). HO providers, on average, received significantly more payment-per-provider during the study period (P < 0.001) compared to all others while RO and IR received significantly less (P < 0.0001). CONCLUSIONS: Among industry payments made to oncologic providers, HO received the highest median and corrected-mean amounts along with the highest proportion of providers receiving open payments.

Hemodialysis Access Maintenance in the Medicare Population: An Analysis Over a Decade of Trends by Provider Specialty and Site of Service.

PURPOSE: To evaluate annual national trends in hemodialysis access maintenance procedures in the Medicare population by specialty and setting. METHODS: Medicare Physician Supplier Procedure Summary Master Files between 2005 and 2015 were analyzed for procedure codes of hemodialysis access angiography and percutaneous thrombectomy. Using physician specialty codes, component procedure volume for endovascular services were queried for radiology, medicine, and surgery. Data entries were analyzed by provider specialty and place of service. Average submitted and allowed charges per intervention were extracted. Linear regression modeling was used to identify trends in number of and allowed charges by specialty and practice setting. RESULTS: Between 2005 and 2015, the frequency of dialysis access angiography for Medicare fee-for-service beneficiaries increased by a total of 74.71% (211,181 to 368,955). Specialty-specific analysis demonstrated volume increases of 220.21% (22,128 to 101,109) for surgery, 249.02% (32,690 to 114,094) for medicine, and 2.81% (135,564 to 139, 367) for radiology. By 2015, an increased trend from hospital-based to non-hospital-based procedures associated with significantly higher reimbursement rates to providers (+18,798 non-hospital-based cases/year, $46.95/year, P ≤ .001) was also observed, with medicine performing the highest volume of non-hospital-based procedures. In this period, there was also a modest total overall increase of percutaneous thrombectomy procedures by 7.75% (61,485 to 66,250). CONCLUSIONS: The frequency of endovascular hemodialysis access maintenance procedures in the Medicare fee-for-service program has increased from 2005 to 2015, with the majority market share transitioning from radiologists to non-radiologists. Similarly, most access maintenance in this time period changed from hospital-based to non-hospital-based interventions.

Endovascular Stent Placement for May-Thurner Syndrome in the Absence of Acute Deep Vein Thrombosis.

PURPOSE: To assess the clinical utility of iliac vein stent placement for patients with chronic limb edema or pelvic congestion presenting with nonocclusive May-Thurner physiology. MATERIALS AND METHODS: All patients (N = 45) undergoing stent placement for May-Thurner syndrome (MTS) without an associated acute thrombotic event between 2007 and 2014 were retrospectively reviewed; 11 were excluded for poor follow-up. A total of 34 patients (28 female) were studied (mean age, 44 y; range, 19-80 y). Average follow-up time was 649 days (median, 488 d; range, 8-2,499 d). RESULTS: The technical success rate was 100% (34 of 34). No major and two minor (5%) complications occurred, and 68% of patients (23 of 34) had clinical success with relief of presenting symptoms on follow-up visits. Technical parameters including stent size and number, stent type, concurrent angioplasty, access site, and resolution of collateral iliolumbar vessels were not found to be statistically related to clinical success (P > .05). Similarly, no significant relation to clinical success was seen for clinical factors such as the type of symptoms, presence of chronic deep vein thrombosis (DVT), or concurrent coagulopathy (P > .05). Female sex was found to correlate with clinical success (82% vs 18%; P = .04). CONCLUSIONS: Iliac stent placement in patients presenting with chronic limb or pelvic symptoms from MTS without acute DVT is associated with clinical success in the majority of patients.

Indwelling and Retrieval Complications of Denali and Celect Infrarenal Vena Cava Filters.

PURPOSE: To compare indwelling and retrieval complications of Denali and Celect filters placed in the infrarenal inferior vena cava (IVC). MATERIALS AND METHODS: A retrospective study was conducted over 2 years at a single institution in which 171 Denali and 162 Celect filters were placed in 333 patients with a mean age of 62.3 years ± 15.7 (161 men; 48.3%). Filter indications included venous thromboembolic disease (n = 320; 96.1%) and surgical prophylaxis (n = 13; 3.9%). A jugular approach was used to place 303 filters (91.0%). Computed tomography (CT) follow-up, complications, and retrieval data were obtained. RESULTS: Follow-up CT imaging was performed on 58 filters from each group with lower incidences of caval strut penetration (one vs 12) and filter tilt (one vs 15) in the Denali filter group (P = .002 and P < .001, respectively). There was no difference in incidences of breakthrough pulmonary embolism (P = .68). Retrieval attempts were performed on 43 Denali and 53 Celect filters with mean indwelling times at retrieval of 128.2 and 144.1 days, respectively (P = .40). Mean fluoroscopy time at retrieval was lower in the Denali group (3.1 min vs 6.0 min; P = .01). There were fewer cases of complex retrieval in the Denali group (n = 2 vs 10; P = .06). Tilt, fluoroscopy time, and air kerma were associated with complex retrieval (P = .04, P < .001, and P < .001, respectively). There was one Denali filter deployment complication that led to retrieval failure. CONCLUSIONS: This study suggests that Denali filters are associated with lower incidences of strut penetration and filter tilt as well as shorter fluoroscopy time at retrieval compared with Celect filters when placed in the infrarenal IVC.