Genicular Artery Embolization for Refractory Hemarthrosis following Total Knee Arthroplasty: Technique, Safety, Efficacy, and Patient-Reported Outcomes.

PURPOSE: To investigate the safety and efficacy of genicular artery embolization for treatment of refractory hemarthrosis following total knee arthroplasty. MATERIAL AND METHODS: Patients who underwent genicular artery embolization with spherical embolics between January 2010 and March 2020 at a single institution were included if they had undergone total knee arthroplasty and subsequently experienced recurrent hemarthrosis. Technical success was defined as the significant reduction or elimination of the hyperemic blush. Clinical success was defined as the absence of clinical evidence of further hemarthrosis. Clinical follow-up was performed 7-14 days after the procedure and at 3-month intervals thereafter via a telephone interview. A total of 117 embolizations, comprising 82 initial, 28 first repeat, and 7 second repeat, were performed. RESULTS: An average of 2.5 arteries was treated per procedure. The superior lateral genicular artery was the most frequently embolized. The most utilized embolic size was 100-300 µm. Follow-up was available for all patients, with a median duration of 21.5 months. 65.9%, 25.6%, and 8.5% of patients underwent 1, 2, and 3 treatments, respectively. Complications occurred following 12.8% of treatments, of which the most common was transient cutaneous ischemia. Technical success was achieved in all cases. Clinical success was achieved in 56%, 79%, and 85% of patients following the first, second, and third treatment, respectively. 83% of patients reported being either satisfied or very satisfied with the overall result. CONCLUSIONS: Targeted genicular artery embolization with spherical embolics is an effective treatment for recurrent hemarthrosis with infrequent serious complications. Repeat embolization should be considered in cases of recurrence following initial therapy.

Multicenter Trial of the VenaTech Convertible Vena Cava Filter.

PURPOSE: To demonstrate rates of successful filter conversion and 6-month major device-related adverse events in subjects with converted caval filters. MATERIALS AND METHODS: An investigational device exemption multicenter, prospective, single-arm study was performed at 11 sites enrolling 149 patients. The VenaTech Convertible Vena Cava Filter (B. Braun Interventional Systems, Inc, Bethlehem, Pennsylvania) was implanted in 149 patients with venous thromboembolism and contraindication to or failure of anticoagulation (n = 119), with high-risk trauma (n = 14), and for surgical prophylaxis (n = 16). When the patient was no longer at risk for pulmonary embolism as determined by clinical assessment, an attempt at filter conversion was made. Follow-up of converted patients (n = 93) was conducted at 30 days, 3 months, and 6 months after conversion. Patients who did not undergo a conversion attempt (n = 53) had follow-up at 6 months after implant. RESULTS: All implants were successful. One 7-day migration to the right atrium required surgical removal. Technical success rate for filter conversion was 92.7% (89/96). Mean time from placement to conversion was 130.7 days (range, 15-391 d). No major conversion-related events were reported. The mean conversion procedure time was 30.7 minutes (range, 7-135 min). There were 89 converted and 32 unconverted patients who completed 6-month follow-up with no delayed complications. CONCLUSIONS: The VenaTech Convertible filter has a high conversion rate and low 6-month device-related adverse event rate. Further studies are necessary to determine long-term safety and efficacy in both converted and unconverted patients.

Characterization of in vivo ablation zones following percutaneous microwave ablation of the liver with two commercially available devices: are manufacturer published reference values useful?

PURPOSE: To analyze in vivo ablation properties of microwave ablation antennae in tumor-bearing human livers by performing retrospective analysis of ablation zones following treatment with two microwave ablation systems. MATERIALS AND METHODS: Percutaneous microwave ablations performed in the liver between February 2011 and February 2013 with use of the AMICA and Certus PR ablation antennae were included. Immediate postablation computed tomography images were evaluated retrospectively for ablation length, diameter, and volume. Ablation length, diameter, and volume indices were calculated and compared between in vivo results and references provided from each device manufacturer. The two microwave antenna models were then also compared versus each other. RESULTS: Twenty-five ablations were performed in 20 patients with the AMICA antenna, and 11 ablations were performed in eight patients with the Certus PR antenna. The AMICA and Certus PR antennae showed significant differences in ablation length (P = .013 and P = .009), diameter (P = .001 and P = .009), and volume (P = .003 and P = .009). The AMICA ablation indices were significantly higher than the Certus PR ablation indices in length (P = .026) and volume (P = .002), but there was no significant difference in ablation diameter indices (P = .110). CONCLUSIONS: In vivo ablation indices of human tumors are significantly smaller than reference ex vivo ablation indices, and there are significant differences in ablation indices and sphericity between devices.

Transarterial Embolization for the Treatment of Chronic Musculoskeletal Pain: A Systematic Review of Indications, Safety, and Efficacy.

OBJECTIVE: The study objective was to evaluate the safety and efficacy of transcatheter arterial "embolization" (TAE) in the treatment of chronic "musculoskeletal pain" refractory to standard therapy. METHODS: PubMed, EMBASE, and Cochrane Central Register of Controlled Trials were searched for original research articles evaluating TAE in patients with musculoskeletal conditions from database inception to January 21, 2020. Search terms employed were as follows: "embolization", "pain", "knee osteoarthritis", joint replacement, epicondylitis, tenderness, inflammation, WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), microspheres, Embozene, geniculate artery, neovascularity, transcatheter, embolic, imipenem/cilastatin sodium, angiogenesis, and "musculoskeletal". Studies involving particle "embolization" for painful musculoskeletal conditions were included. Studies of TAE for hemarthrosis or malignancy-related "musculoskeletal pain" were excluded. RESULTS: The primary search yielded 1,099 sources; 7 articles and 4 abstracts were included for data extraction. All were cohorts or case series, with low risk of bias and moderate to poor level of evidence. Heterogeneity between studies was high, precluding meta-analysis. The reviewed studies reported the safety and efficacy of TAE for the treatment of "knee osteoarthritis"; adhesive capsulitis of the shoulder; tendinopathy/enthesopathy of the knee, shoulder, elbow, and ankle; and cervical myalgia. All TAEs were reported as technically successful without major complications or subsequent serious adverse events, including no reported osteonecrosis, cutaneous ulceration, limb ischemia, cartilage degeneration, or myotendinous injury. TAE significantly reduced pain and improved function for all of the treated conditions, with durable response up to 24 months post procedure. CONCLUSION: TAE appears to be a safe and effective treatment for some types of chronic refractory "musculoskeletal pain". Randomized placebo-controlled studies are necessary to confirm these findings.

Magnetic resonance angiography in the management of recurrent hemarthrosis after total knee arthroplasty.

Spontaneous hemarthrosis is an infrequent but disabling complication after total knee arthroplasty. The purpose of this case series is to demonstrate the utility of magnetic resonance angiography (MRA) in the evaluation of hemarthrosis after total knee arthroplasty. Patients presenting with hemarthrosis unexplained by trauma, anticoagulation, or a bleeding diathesis were retrospectively identified. Eighteen patients were referred for MRA to evaluate recurrent hemarthrosis after failing conservative therapy (n = 16) or synovectomy (n = 2). Despite artifact caused by the metallic components, diagnostic evaluation of regional vessels was made. In 12 of 13 cases that underwent embolization or synovectomy, a hypertrophic feeding artery (or arteries) was visualized on MRA. One case of negative MRA did not have subsequent surgery, and we are unable to comment on the rate of false-positives because all patients in this case series had evidence of bleeding. By characterizing the vascular anatomy and identifying a dominant artery (or arteries) supplying the hypervascular synovium, MRA can serve as a guide for subsequent embolization or synovectomy, as indicated.

Inferior vena cava filter placement in orthopedic surgery.

Inferior vena cava (IVC) filters were developed for the treatment of venous thromboembolism but in high-risk patients are often used for prophylaxis instead. In the study reported here, we reviewed all the orthopedic surgery cases in which IVC filters were used at our institution in 2005. Charts were analyzed and patients contacted by telephone for long-term follow-up. IVC filters were used in 90 (0.96%) of the 9,348 inpatient orthopedic surgeries. Sixty-one percent of filters were placed for prophylaxis, though only 42% of patients with prophylactic filters had a contraindication to anticoagulation. Eighty-one percent of patients with prophylactic filters who received anticoagulation received warfarin. Ratios of prophylactic-to-treatment filters were 3.25 for fracture surgeries, 2.1 for arthroplasties, and 0.89 for spine surgeries. Five percent of patients with prophylactic filters developed deep vein thrombosis. Fifty-two percent of filters were retrievable, but only 40% of those were removed a mean of 5.1 months (SD, 3.9 months) after placement. Filter removal was associated with complications in 11% of patients, and in another 10% the filter could not be removed. Forty-one patients were contacted a mean of 21 months (SD, 3 months) after filter placement. Only 32% of those who still had filters were on anticoagulation at follow-up.

Renal artery embolization: clinical indications and experience from over 100 cases.

OBJECTIVE: To review current indications and techniques for renal artery embolization (RAE) and more specifically to review cases of RAE before nephrectomy for treating patients with a large renal mass. PATIENTS AND METHODS: All RAEs done at our institution between May 1993 and December 2005 were reviewed. Patients were identified using a database assembled by the Division of Cardiovascular Interventional Radiology. Indications, techniques and RAE-related complications were then obtained from a retrospective review of medical records. Additional data for patients undergoing preoperative infarction were acquired, including estimated blood loss (EBL), transfusion requirement, pathological size, subtype, grade, stage, and level of tumour thrombus if present. RESULTS: In all, there were 121 RAEs, 69 in males and 52 in females (mean age 57.6 years, range 11-89). Metallic microcoils were the most often used embolization agent, followed by acrylic microspheres (embospheres), polyvinyl alcohol particles, absolute ethanol, and Gelfoam (Pharmacia & Upjohn, USA). The most common indication for RAE was infarction before nephrectomy (54.5%). Other indications included symptomatic angiomyolipomas, palliation of unresectable renal cancer, haemorrhage, perinephric bleeding in end-stage renal disease, vascular lesions, malignant hypertension, and sequelae of end-stage renal disease. RAE-associated complications including coil migration, incomplete embolization, and groin haematoma (in 5.0%). Symptoms of post-infarction syndrome were common, with 74.4% of patients having flank pain, nausea, or vomiting; the vast majority of these symptoms were mild and self-limited. In patients having nephrectomy after RAE the median (range) interval from RAE was 2 (0-78) days. The mean tumour size was 11.2 (3.5-25) cm and 46% of patients had tumour thrombus present in either the renal vein or inferior vena cava (IVC). The mean (median) overall EBL in patients having nephrectomy after RAE was 1048 (725) mL. The mean transfusion requirement over the course of hospitalization was 3.9 units of packed red blood cells. CONCLUSIONS: RAE is a safe and effective therapeutic tool for many urological, renal and vascular conditions. Its use has increased at our institution due to improved techniques, embolization materials, and our increasing use of RAE as an adjuvant procedure for patients requiring nephrectomy with or without IVC thrombectomy. There are many potential operative advantages for patients having RAE before surgery, with minimal morbidity. It is likely that the lack of prospective randomized trials is the primary reason why it is underutilized in the preoperative setting.

Quantitative evaluation of susceptibility and shielding effects of nitinol, platinum, cobalt-alloy, and stainless steel stents.

The purpose of this study is to quantitatively estimate the shielding and susceptibility effects of commonly used metallic stents on MR signal. Two experiments were performed using a 3D gradient echo sequence with short TE to image a stent phantom: 1) short TR and high flip angle (contrast enhanced MRA parameters), and 2) long TR (TR >> T(1)) and low flip angle. The factor characterizing susceptibility effects was estimated from the signal phase of the first experiment, and then the factor characterizing the shielding effects was derived from the second experiment. Susceptibility induced signal loss was negligible (<1%) for nonstainless-steel (nitinol, platinum, and cobalt-alloy) stents and totally destructive (100%) for the stainless steel stent. Signal loss due to RF shielding was 31-62% for nitinol stents, 14-50% for platinum stents, 50-77% for the cobalt-alloy stents (undetermined for the stainless steel stent), varied with stent orientation, diameter, and wall geometry. In summary, stents made of nitinol, platinum, and cobalt-alloy have negligible susceptibility effects but stents made of stainless steel may have complete dephasing. All stents have substantial shielding effects, which vary with composition, geometry, and orientation. Large platinum stents may have the smallest artifacts and are the best suited for postinterventional MR imaging.

Three-dimensional MR angiography in imaging platinum alloy stents.

PURPOSE: To evaluate visualization inside platinum stents with three-dimensional contrast-enhanced magnetic resonance angiography (CE-MRA). MATERIALS AND METHODS: Breath-hold three-dimensional gadolinium (Gd) MRA was performed on 18 patients with 22 platinum stents in the renal (n = 18), celiac (n = 1), superior mesenteric (n = 1), and iliac (n = 2) arteries. Electronic calibers were used to measure the lumen diameter within the stent and just distal to the stent to calculate percent stenosis. MRA accuracy was determined from the difference between percent stenosis measured on MRA and digital subtracted angiography (DSA). The patients were imaged at flip angles of 45 degrees , 60 degrees , 75 degrees , 90 degrees , and 150 degrees . RESULTS: MRA demonstrated the stent lumen in all of the patients, with a mean difference between MRA and DSA of 21%. For stents oriented parallel to B0 (iliac arteries) the difference was only 10%, as compared to 22% for stents perpendicular to B0. The flip angle with the best agreement between MRA and DSA was 75 degrees (16%). CONCLUSION: The lumen of a platinum stent can be imaged with three-dimensional CE-MRA, although grading of restenosis has limited accuracy. The best results were obtained with a flip angle of 75 degrees and for stents in the iliac arteries parallel to B0.

Peripheral vascular disease: combined 3D bolus chase and dynamic 2D MR angiography compared with x-ray angiography for treatment planning.

PURPOSE: To compare combined three-dimensional (3D) and two-dimensional (2D) contrast material-enhanced magnetic resonance (MR) angiography with x-ray angiography for planning treatment of peripheral vascular disease. MATERIALS AND METHODS: Three radiologists retrospectively reviewed the pretreatment x-ray angiographic and MR angiographic studies obtained in 30 consecutive patients: 15 patients (15 limbs) evaluated for limb salvage and 15 patients (20 limbs) evaluated because of claudication. MR angiography included acquisition of 2D contrast-enhanced MR digital subtraction angiograms of the area from the adductor canal to the feet and 3D spoiled gradient-recalled-echo bolus chase MR angiograms obtained in three stations from the aorta to the middle portion of the calf. Each reader reviewed the x-ray and MR angiograms to determine the inflow and outflow segments for a hypothetical bypass graft placement. RESULTS: The three readers selected identical segments for inflow at MR angiography and x-ray angiography in 32, 32, and 35 of the 35 limbs evaluated (mean percentages of agreement [95% CI ]: 91% [77%, 98%], 91% [77%, 98%], and 95% [90%, 100%], respectively). The readers selected identical segments for outflow in 32, 32, and 34 of the 35 limbs evaluated (mean percentages of agreement [95% CI]: 91% [77%, 98%], 91% [77%, 98%], and 97% [85%, 100%], respectively). CONCLUSION: Preliminary data support the combining of 2D MR digital subtraction angiography with 3D bolus chase MR angiography to extend the utility of 3D MR angiography in treatment planning to include patients being evaluated for limb salvage, as well as those being evaluated for claudication.