Voxel-based tumor dose correlates to complete pathologic necrosis after transarterial radioembolization for hepatocellular carcinoma.

PURPOSE: The transarterial radioembolization (TARE) dose is traditionally calculated using the single-compartment Medical Internal Radiation Dose (MIRD) formula. This study utilized voxel-based dosimetry to correlate tumor dose with explant pathology in order to identify dose thresholds that predicted response. METHODS: All patients with HCC treated with TARE using yttrium-90 [90Y] glass microspheres at a single institution between January 2015 - June 2023 who underwent liver transplantation were eligible. The [90Y] distribution and dose-volume histograms were determined using Simplicity90 (Mirada Medical, Oxford UK) with a Bremsstrahlung SPECT/CT. A complete response was assigned if explant pathology showed complete necrosis and the patient had not undergone additional treatments to the same tumor after TARE. Logistic regression and receiver operator characteristic (ROC) curves were constructed to evaluate dose thresholds correlated with response. RESULTS: Forty-one patients were included. Twenty-six (63%) met criteria for complete response. Dose to 95% (D95), 70% (D70), and 50% (D50) of the tumor volume were associated with likelihood of complete response by logistic regression (all p < 0.05). For lesions with complete response versus without, the median D95 was 813 versus 232 Gy, D70 was 1052 versus 315 Gy, and D50 was 1181 versus 369 Gy (all p < 0.01). A D95 > 719 Gy had the highest accuracy at 68% (58% sensitivity, 87% specificity) for predicting complete response. Median percent of tumor volume receiving at least 100 Gy (V100), 200 Gy (V200), 300 Gy (V300), and 400 Gy (V400) also differed by pathologic response: the median V100, V200, V300, and V400 was 100% versus 99%, 100% versus 97%, 100% versus 74%, and 100% versus 43% in the complete response versus non-complete response groups, respectively (all p < 0.05). CONCLUSION: Voxel-based dosimetry was well-correlated with explant pathology. The D95 threshold had the highest accuracy, suggesting the D95 may be a relevant target for multi-compartment dosimetry.

Dynamic Contrast-enhanced CT Lymphangiography to Quantify Thoracic Duct Lymphatic Flow.

Background CT lymphangiography has been used to image the lymphatic anatomy and assess lymphatic abnormalities. There is, however, a need to develop a method for quantification of lymphatic flow rate in the thoracic duct (TD). Purpose To develop and validate a TD lymphatic flow measurement technique using dynamic contrast-enhanced CT lymphangiography. Materials and Methods Lymphatic flow rate was measured with two techniques: a first-pass analysis technique based on a single compartment model and a thresholding technique distinguishing between opacified and nonopacified voxels within the TD. The measurements were validated in a swine animal model between November 2021 and September 2022. CT images were acquired at 100 kV and 200 mA using a fast-pitched helical scan mode covering the entire TD following contrast material injection into the bilateral inguinal lymph nodes. Two helical CT scans, acquired at the base and peak contrast enhancement of the TD, were used to measure lymphatic flow rate. A US flow probe surgically placed around the TD provided the reference standard measurement. CT lymphatic flow measurements were compared with the reference US flow probe measurements using regression and Bland-Altman analysis. Repeatability was determined using repeated flow measurements within approximately 10 minutes of each other. Results Eleven swine (10 male; mean weight, 43.6 kg ± 2.6 [SD]) were evaluated with 71 dynamic CT acquisitions. The lymphatic flow rates measured using the first-pass analysis and thresholding techniques were highly correlated with the reference US flow probe measurements (r = 0.99 and 0.91, respectively) and showed good agreement with the reference standard, with Bland-Altman analysis showing small mean differences of 0.04 and 0.05 mL/min, respectively. The first-pass analysis and thresholding techniques also showed good agreement for repeated flow measurements (r = 0.94 and 0.90, respectively), with small mean differences of 0.09 and 0.03 mL/min, respectively. Conclusion The first-pass analysis and thresholding techniques could be used to accurately and noninvasively quantify TD lymphatic flow using dynamic contrast-enhanced CT lymphangiography. © RSNA, 2023 See also the editorial by Choyke in this issue.

Comparison of Clinical Performance of VectorFlow and Palindrome Symmetric-Tip Dialysis Catheters: A Multicenter, Randomized Trial.

PURPOSE: To compare clinical performance of 2 widely used symmetric-tip hemodialysis catheters. MATERIALS AND METHODS: Patients with end-stage renal disease initiating or resuming hemodialysis were randomized to receive an Arrow-Clark VectorFlow (n = 50) or Palindrome catheter (n = 50). Primary outcome was 90-d primary unassisted catheter patency. Secondary outcomes were Kt/V ([dialyzer urea clearance × total treatment time]/total volume of urea distribution), urea reduction ratio (URR), and effective blood flow (QB). RESULTS: Primary unassisted patency rates with the VectorFlow catheter at 30, 60, and 90 d were 95.5% ± 3.3, 87.2% ± 7.3, and 80.6% ± 9.8, respectively, compared with 89.1% ± 6.2, 79.4% ± 10.0, and 71.5% ± 12.6 with the Palindrome catheter (P = .20). Patients with VectorFlow catheters had a mean Kt/V of 1.5 at 30-, 60-, and 90-day time points, significantly higher than the mean Kt/V of 1.3 among those with Palindrome catheters (P = .0003). URRs were not significantly different between catheters. Catheter QB rates exceeded National Kidney Foundation-recommended thresholds of 300 mL/min at all time points for both catheters and were similar for both catheters (median, 373 mL/min). Catheter failure, ie, poor flow rate requiring guide-wire exchange or removal, within the 90-day primary outcome occurred in 3 VectorFlow subjects and 5 Palindrome subjects (P = .72). Infection rates were similar, with 0.98 infections per 1,000 catheter days for VectorFlow catheters compared with 2.62 per 1,000 catheter days for Palindrome catheters (P = .44). CONCLUSIONS: The 90-day primary patency rates of Palindrome and VectorFlow catheters were not significantly different, and both achieved sustained high QB through 90 day follow-up. However, dialysis adequacy based on Kt/V was consistently better with the VectorFlow catheter versus the Palindrome.

Inferior Vena Cava Reconstruction in Symptomatic Patients Using Palmaz Stents: A Retrospective Single-Center Experience.

BACKGROUND: The use of stents for treating central venous occlusion is well described. Limited evidence exists related to Palmaz balloon-expandable stent use in inferior vena cava (IVC) reconstruction. We analyzed patency and complication rates after IVC reconstruction using Palmaz stents. METHODS: From 2002 to 2019, 37 patients (mean age: 51 year) underwent IVC reconstruction with 68 Palmaz stents. Indications were symptomatic chronic venous obstruction in the infrarenal (n = 25) and intrahepatic (n = 12) IVC. Demographic, operative, and imaging data were evaluated. Clinical data, abdominal CT, and/or duplex ultrasound were used to determine patency at follow-up. RESULTS: Restoration of caval patency was achieved in all patients, with complications in 2/37 (5.4%) patients (thrombus formation within the stent; stent embolization eight days after placement). Follow-up data were available for 27 patients. Primary patency was maintained through last follow-up in 19/27 (70%) patients (mean: 1.1 year), with successful stent redilation performed in 6 patients. Mean duration of primary-assisted patency (n = 5) was 1.2 year. Late lumen loss was (n = 13) was 40% during a mean time to follow-up of 2.0 years. Primary patency in patients with occlusion secondary to malignancy was 109 day (range: 1 day-1.0 year), whereas primary patency in patients with occlusion from other etiologies was 1.1 year (range: 2 day-5.9 year). The Kaplan-Meier analysis demonstrated primary and primary-assisted patency of 66% and 84%, respectively, at 24 and 48 months. CONCLUSIONS: Palmaz balloon-expandable stents for IVC reconstruction is feasible and effective for symptomatic IVC occlusion. Risk of stent migration was low.

Endovascular Therapy for Below-the-Elbow Arterial Disease: An Initial Single-Center Experience.

Purpose: To evaluate the technical success, clinical success, and complication rates of endovascular revascularization for below-the-elbow (BTE) peripheral artery disease. Materials and Methods: A retrospective review was performed of 19 patients (mean age 63 years; 12 men) with critical hand ischemia (CHI) who underwent 25 interventions in 19 arms between October 2010 and June 2017. Access was attained using 4-F or 5-F sheaths via antegrade brachial, retrograde radial, or fistula/graft access routes depending on the target vessel. A 0.018-inch hydrophilic microwire was used for intimal or subintimal recanalization. Angioplasty was performed over a 0.014-inch guidewire using low-profile balloons. The primary endpoint of the study was technical success, defined as successful lesion crossing/dilation, with residual stenosis <30%. Clinical success referred to improvement in pain and/or steal symptoms. Results: Technical success was achieved in 88% (22 of 25 procedures), with no significant difference in outcome associated with indications or baseline vessel disease. Complications occurred in 6 cases, of which 5 were minor and 1 was major. Clinical success was achieved in 12 of 14 patients with available follow-up; 5 of 7 patients with ulcers experienced wound healing. Conclusion: Endovascular revascularization for BTE occlusive disease is an effective and safe strategy for treating CHI.

The 2017 Integrated IR Residency Match: Results of a National Survey of Applicants and Program Directors.

PURPOSE: To characterize and compare the experiences of matched applicants and program directors (PDs) participating in the first large-scale integrated interventional radiology (IR) residency match. MATERIALS AND METHODS: Survey questionnaires were distributed nationally to integrated IR applicants who matched in the 2017 Match cycle and PDs. Both groups were questioned regarding their experiences with the application, interview, rank, and match processes as well as applicant-specific and PD-specific information. Summary and descriptive statistics were applied to responses, and comparison of Likert scale responses was performed by two-sample t test. RESULTS: Sixty-one matched applicants (51.3%) and 34 PDs (55.7%) responded to the survey. Regarding the match process, applicants believed United States Medical Licensing Examination (USMLE) Step 1 score (P = .002) and connection to a program's geographic location (P = .006) were significantly more important than PDs did, whereas PDs ranked grades (P = .049), class rank (P = .011), academic awards (P = .003), additional degrees (P < .001), and USMLE Step 2 Clinical Skills score (P < .001) as significantly more important factors than applicants did. Additional information regarding demographic data, medical school experiences in IR, application strategies, interview experiences, rank lists, the intern year, and match results are reported. CONCLUSIONS: The completion of the first large-scale integrated IR match represents a paradigm shift in the way in which IR practitioners are recruited and trained. This study provides valuable benchmark data and analysis that can be used to improve efforts to match the best-fitting applicants into the integrated IR residency and improve future match cycles for applicants and PDs alike.

Increasing Medical Student Exposure to IR through Integration of IR into the Gross Anatomy Course.

PURPOSE: To compare medical student knowledge of and interest in interventional radiology (IR) before and after the integration of an IR lecture series within the gross anatomy course. MATERIALS AND METHODS: Four elective IR lectures were scheduled to coincide with the relevant anatomy dissection curriculum. Anonymous surveys were distributed to 146 students before and after the lectures regarding students' knowledge of and interest in IR, responsibilities of an IR physician, and IR training pathways. Those who did not attend served as controls. RESULTS: Response rates were 67% (n = 98) in the prelecture group, 55% (n = 22) in the group who attended the lecture, and 28% (n = 30) in the control group. A total of 73% of the prelecture group reported little knowledge of IR compared with other specialties. This decreased to 27% in those who attended the lecture (P < .001). A total of 32% of those who attended believed they had more knowledge of IR than any other specialty, compared with 7% of controls (P value not significant) and 2% of the prelecture group (P < .001). Those in attendance could name a significantly greater number of IR procedures (mean, 1.82) than the prelecture group (mean, 0.57; P < .001). A total of 64% of those who attended would consider a career in IR, compared with 24% in the prelecture group and 33% in the control group (P < .05). A total of 68% of those who attended had knowledge of the IR residency, compared with 5% in the prelecture group and 33% in the control group (P < .05). CONCLUSIONS: Integration of IR education into the gross anatomy course proved to be a highly effective way of teaching preclinical students about IR and generating interest in the field.

Initial Clinical Experience: Symmetric-Tip Dialysis Catheter with Helical Flow Characteristics Improves Patient Outcomes.

PURPOSE: To report preliminary clinical experience with a new symmetric-tip dialysis catheter compared with a conventional split-tip catheter. MATERIALS AND METHODS: Over a 5-month period, patients requiring a tunneled catheter for hemodialysis or undergoing exchange of a dysfunctional dialysis catheter at a tertiary academic medical center were retrospectively analyzed. Patients underwent placement of a VectorFlow or Ash Split Cath catheter at the discretion of the inserting interventional radiologist. Patient demographics, catheter patency, mean blood flow rate, and arterial and venous pressures were compared according to catheter type. Catheter failure was analyzed based on clinical and anatomic variables by using a multivariate Cox proportional-hazards model. RESULTS: A total of 33 VectorFlow and 46 Ash Split Cath catheters were placed. Patients in the VectorFlow group had significantly higher body mass index (P = .013) and Charlson Comorbidity Index (P = .049), as well as more non-internal jugular vein placements. At 120 days, 89% of VectorFlow catheters remained functional, compared with 45% of Ash Split Cath catheters (P = .046). The VectorFlow catheter was associated with 16% lower arterial pressures during dialysis (P = .009); mean blood flow rate was equivalent. On multivariate analysis, the risk of catheter failure was 13.3 times higher in the Ash Split Cath group compared with the VectorFlow group (P = .004). Left-sided catheters were also predictive of catheter failure (relative risk = 5.5; P = .02). CONCLUSIONS: The VectorFlow catheter was associated with a significant increase in intervention-free catheter patency compared with the Ash Split Cath catheter, with equivalent flow at lower arterial pressures during dialysis.

Single-Session Ablative Transarterial Radioembolization for Patients with Hepatocellular Carcinoma to Streamline Care: An Initial Experience.

PURPOSE: Transarterial radioembolization (TARE) for hepatocellular carcinoma (HCC) is performed after a mapping angiogram involving infusion of radiolabeled macroaggregated albumin to assess for non-target embolization and pulmonary shunting. The purpose of this case series was to evaluate the safety and feasibility of single-session TARE without the initial procedure. MATERIALS AND METHODS: A single-institution case series of 16 consecutive procedures on 15 patients with 18 tumors who underwent an attempted single-session TARE procedures with glass microspheres are presented. A lung shunt fraction (LSF) of 5% was assumed for planning purposes. RESULTS: Sixty-seven percent (10/15) of patients were male with a median age of 72 years. Median tumor size was 2.5 cm (IQR 2.0-3.2 cm). Sixteen of the 18 targeted tumors were untreated prior to the single-session TARE. Rate of technical success was 88% (14/16). Two patients did not ultimately receive a single-session TARE due to intraprocedural findings. The mean administered activity was 2.0 GBq, and the mean MIRD dose was 464 Gy based on pre-treatment anatomic imaging and 800 Gy based on cone-beam CT. There were no cases of radiation pneumonitis. Mean post-procedural calculated lung dose was 4.9 Gy (range 3.1-9.3) based on SPECT. CONCLUSIONS: An initial experience with single-session TARE using Y-90 glass microspheres without pre-procedural mapping angiography and lung shunt estimation demonstrates that it is a feasible and safe treatment option for select patients with small (< 5 cm) HCC. LEVEL OF EVIDENCE IV: Level 4 case series.

Rigid bronchoscopic management of complications related to endobronchial stents after lung transplantation.

OBJECTIVES: We reviewed the utility of rigid bronchoscopy in the management of complications resulting from placement of metallic endobronchial stents after lung transplantation. METHODS: A retrospective review was performed of all lung transplant patients who required metallic endobronchial stenting between 2005 and 2009. The patients' medical records were reviewed, and details regarding stent placement, complications, and removal were recorded. RESULTS: A total of 43 metallic stents were placed in 22 patients who had unilateral or bilateral lung transplantation. Stent complications occurred in 18 cases (42%) at a mean of 285 days after placement and included stent collapse, stent breakdown, stent migration, ingrowth of granulation tissue, and coughing up of fractured pieces of stent. Of the 43 stents placed, only 4 (9%) had to be removed. Removal was readily accomplished by rigid bronchoscopic techniques, even when some endothelial ingrowth had occurred. CONCLUSIONS: Lung transplantation presents unique challenges in airway management. Endobronchial stenting plays an important role in the management of anastomotic stenosis and bronchomalacia in these patients. Although metallic stents have significant advantages, complications often arise that occasionally necessitate their removal. Rigid bronchoscopy is a valuable tool in the management of endobronchial stent complications after lung transplantation.

Successful mechanical thrombectomy and stent exclusion of sacral chordoma tumor thrombus.

A 77-year-old man with history of sacral chordoma and pulmonary embolism presented to the emergency room with a 1-day history of diffuse left flank and lower extremity swelling. The patient was found to have thrombus in the left common and external iliac veins. The patient was brought to Interventional Radiology for mechanical thrombectomy using the Inari ClotTriever and a sample of extracted thrombus was sent to pathology. Analysis on the sample was positive for sacral chordoma, consistent with tumor thrombus. The patient returned after 6 weeks with similar symptoms and repeat mechanical thrombectomy was performed with the Inari ClotTriever and stent placement through the left common and external iliac vein with an Ovation iX stent graft. The patient remained asymptomatic following the second procedure at repeat follow-up at 6 weeks.

Utility of Cone-Beam CT for Bronchial Artery Embolization and Chemoinfusion: A Single-Institution Retrospective Case Series.

PURPOSE: To describe the technique and document utility of adjunctive cone-beam CT (CBCT) in patients undergoing bronchial artery embolization (BAE) or chemoinfusion (BAC). MATERIALS AND METHODS: Between August 2010 and February 2021, 26 patients (62 bronchial arteries) were evaluated with CBCT in addition to the usual digital subtraction angiography (DSA) during BAE or BAC. 19 patients (43 arteries) underwent BAE for hemoptysis; 7 patients (19 arteries) had BAC for palliation of lung malignancy. Retrospective review of procedural reports and the archived DSA and CBCT images was assessed for (1) whether CBCT findings added unique diagnostic information prior to treatment of target arteries compared to DSA alone; and (2) whether these unique CBCT findings led to modification of embolization or chemoinfusion technique. RESULTS: In 61 of 62 (98%) interrogated bronchial arteries, CBCT provided additional unique diagnostic information over planar DSA, primarily cross-sectional assessment of the spinal canal for spinal arteries. In 46/62 (74%) of the bronchial arteries the unique information did not lead to a change in therapeutic technique. In 15 bronchial arteries (24%), the added information from CBCT led to change in embolization and/or chemoinfusion technique. Embolization of one small unrecognized spinal artery branch (1.6%), which was missed intra-procedurally but retrospectively seen on CBCT led to transient spinal cord ischemia. CONCLUSIONS: These results suggest that adjunctive use of CBCT technique may improve diagnostic confidence from information provided by DSA in nearly all cases of BAE and BAC leading to improved therapeutic targeting or change in technique of embolization or chemoinfusion.

Variability in biopsy quality informs translational research applications in hepatocellular carcinoma.

In the era of precision medicine, biopsies are playing an increasingly central role in cancer research and treatment paradigms; however, patient outcomes and analyses of biopsy quality, as well as impact on downstream clinical and research applications, remain underreported. Herein, we report biopsy safety and quality outcomes for percutaneous core biopsies of hepatocellular carcinoma (HCC) performed as part of a prospective clinical trial. Patients with a clinical diagnosis of HCC were enrolled in a prospective cohort study for the genetic, proteomic, and metabolomic profiling of HCC at two academic medical centers from April 2016 to July 2020. Under image guidance, 18G core biopsies were obtained using coaxial technique at the time of locoregional therapy. The primary outcome was biopsy quality, defined as tumor fraction in the core biopsy. 56 HCC lesions from 50 patients underwent 60 biopsy events with a median of 8 core biopsies per procedure (interquartile range, IQR, 7-10). Malignancy was identified in 45/56 (80.4%, 4 without pathology) biopsy events, including HCC (40/56, 71.4%) and cholangiocarcinoma (CCA) or combined HCC-CCA (5/56, 8.9%). Biopsy quality was highly variable with a median of 40% tumor in each biopsy core (IQR 10-75). Only 43/56 (76.8%) and 23/56 (41.1%) samples met quality thresholds for genomic or metabolomic/proteomic profiling, respectively, requiring expansion of the clinical trial. Overall and major complication rates were 5/60 (8.3%) and 3/60 (5.0%), respectively. Despite uniform biopsy protocol, biopsy quality varied widely with up to 59% of samples to be inadequate for intended purpose. This finding has important consequences for clinical trial design and highlights the need for quality control prior to applications in which the presence of benign cell types may substantially alter findings.

Safety and Efficacy of Arterial Closure Devices Following Antegrade Femoral Access: A Case-Control Study.

PURPOSE: Vascular closure device (VCD) use following antegrade femoral access may present unique challenges relative to retrograde access. We retrospectively compared safety and efficacy of these devices between antegrade and retrograde patient cohorts undergoing percutaneous intervention. MATERIALS AND METHODS: Over a 5-year period, a consecutive series of 107 limbs in 84 patients underwent VCD arteriotomy closure following percutaneous revascularization using an antegrade approach (VCD-A). Device deployment success rates, time to ambulation, and complication rates were compared to a contemporaneous control group of 401 limbs in 305 patients who underwent closure following retrograde access (VCD-R) during revascularization or embolization procedures. RESULTS: Closure was attempted in VCD-A using 53 StarClose, 35 Perclose, and 19 Angio-Seal devices. Hemostasis (without supplemental manual compression) was achieved in 86/107 (80.4%) limbs. Closure was attempted in VCD-R using 215 StarClose, 119 Perclose, and 67 Angio-Seal devices with hemostasis in 357/401 (89.0%) limbs. Device deployment failure occurred in 7/107 (6.5%) of VCD-A and 20/401 (5.0%) of VCD-R (P = .52), independent of specific device type. Femoral pseudoaneurysm developed in 1/107 and 1/401 of VCD-A and VCD-R (P = .31), and minor hematoma developed in 3/107 and 8/401 of the VCD-A and VCD-R (P = .61). Mean time to ambulation was 204.1 minutes in VCD-A and 204.8 minutes in VCD-R (P = .97). CONCLUSION: Antegrade femoral closure was associated with high rates of technical success and low complications, similar to retrograde closure. Time to ambulation was the same in both groups despite higher heparin doses in the antegrade patients.

Nonfemoral Arterial Hemostasis Following Percutaneous Intervention Using a Focused Compression Device.

PURPOSE: Upper extremity and tibiopedal arterial access are increasingly used during endovascular therapies. Balloon compression hemostasis devices in these anatomic locations have been described, but most utilize a compression surface extending well beyond the puncture site. We report single-center experience with an arterial puncture-focused compression device following upper extremity and tibiopedal access. PATIENTS AND METHODS: A series of 249 focused compression hemostasis devices (VasoStat, Forge Medical, Bethlehem, Pennsylvania, USA) were used in 209 patients following lower extremity (n = 63) and upper extremity (n = 186; radial: 90%) arterial access procedures using 4-7 French sheaths. Demographic, operative, and follow-up data were collected. Logistic regression was used to evaluate potential association between patient/operative variables and time to hemostasis. RESULTS: Primary hemostasis was achieved in 97.2% (242/249) following sheath removal; in 7 cases (2.8%) puncture site oozing occurred after initial device removal and required reapplication. Secondary hemostasis was 100% (249/249). Seven complications (2.8%) were recorded: 5 minor hematomas (2%) and 2 transient access artery occlusions (0.8%). Mean time to hemostasis enabling device removal was 55 ± 28 min. Elevated body mass index (BMI) was not associated with increased time to hemostasis (p = 0.31). Accessed artery, sheath size, and heparin dose were also not associated with time to hemostasis (p = 0.64; p = 0.74; p = 0.75, respectively). CONCLUSIONS: The focused compression hemostasis device enabled rapid hemostasis with a low complication rate. Time to hemostasis was independent of BMI, access site, sheath size, or heparin dose.

Prediction of Limb Salvage Following Percutaneous Vascular Intervention Using a Composite Tibial Artery Perfusion Score.

PURPOSE: To assess a novel tibial artery perfusion score (TPS) for predicting limb salvage in critical limb ischemia (CLI) patients undergoing percutaneous vascular intervention (PVI). PATIENTS AND METHODS: A consecutive cohort of 115 CLI patients undergoing PVI in 144 limbs from 2011 to 2016 was analyzed. TPS comprised a 27-point scale based on: (1) patent tibial vessels following PVI, (2) severity of calcification of the tibial arteries, (3) presence of an intact pedal arch following intervention, (4) whether or not revascularization was direct or indirect based on the target angiosome, (5) presence of angiosome blush at the completion of index intervention. Limbs were stratified into (1) High [21-27 points], (2) Medium [13-20 points], and (3) Low [0-12 points] TPS. Predictive value of TPS was evaluated using logistic regression and Cox proportional hazards models. RESULTS: The median follow-up was 15.7 months (range 0.4-69.9 months). Limb salvage in High, Medium, and Low TPS groups was 90.6%, 85.9%, and 55.6%, respectively, as freedom from the composite outcome: (1) limb complication resulting in death, (2) tibial bypass surgery, (3) above-the-knee amputation, or (4) below-the-knee amputation in patients without supratibial disease at the time of PVI. TPS was significantly associated with limb salvage defined as freedom from both the composite outcome and major amputation. CONCLUSIONS: Based on this preliminary investigation, TPS was associated with limb salvage in CLI limbs, particularly in high-risk limbs. Further validation in a prospective cohort may identify patients with high-risk limbs in need of closer surveillance and earlier reintervention. LEVEL OF EVIDENCE: Level IV, case series.