Developing and Evaluating a Simulator for Complex IVC Filter Retrieval.

RATIONALE AND OBJECTIVES: Simulation models allow trainees to acquire and develop procedural skills without compromising patient safety. Complex inferior vena cava (IVC) filter retrieval requires the operator to be proficient at using devices, such as endobronchial forceps, and advanced techniques to carefully dissect free embedded filter tips encased in fibrous tissue adherent to the IVC. Therefore, it is important to develop an effective, inexpensive model to simulate tip-embedded IVC filter retrieval. MATERIALS AND METHODS: Silicone tubes (Flexi-Seal SIGNAL, ConvaTec Inc., Skilman, NJ), IVC filters (Cook Günther Tulip Vena Cava Filter, Cook Medical, Bloomington, IN), and endobronchial forceps (Lymol Medical, Woburn, MA) were obtained to assemble the model. A total of 12 combinations of adhesive binding methods were used to adhere IVC filter fragments to the silicone tubes, and these were blind tested. A single operator with over 10 years of experience using forceps scored the adhesives subjectively on a three-point scale for adherence, elasticity, and tactile feel. The adhesive most similar to IVC fibrous tissue was selected to assemble the final tip-embedded IVC filter model. 20 trainees were then assigned to practice on the model. A 3-point scale scoring metric objectively measured confidence before and after training on the model. RESULTS: Sil-poxy Silicone Adhesive (Smooth-On, Macungie, PA) was found to be the most similar to human IVC fibrous tissue with an average score of 3 of 3 on all metrics. Comparing scores from before and after use of the model, trainee confidence improved significantly (p < 0.1) in all three categories from 1.20 to 2.10 (handling forceps), 1.05 to 2.15 (understanding tactile feel of fibrous tissue), and 1.05 to 1.70 (overall confidence). CONCLUSION: The development of a low-cost simulator for embedded IVC filters is feasible and can be used to improve trainee confidence and skill for complex IVC filter retrieval.

Determining the Optimal Number of Core Needle Biopsy Passes for Molecular Diagnostics.

PURPOSE: The number of core biopsy passes required for adequate next-generation sequencing is impacted by needle cut, needle gauge, and the type of tissue involved. This study evaluates diagnostic adequacy of core needle lung biopsies based on number of passes and provides guidelines for other tissues based on simulated biopsies in ex vivo porcine organ tissues. METHODS: The rate of diagnostic adequacy for pathology and molecular testing from lung biopsy procedures was measured for eight operators pre-implementation (September 2012-October 2013) and post-implementation (December 2013-April 2014) of a standard protocol using 20-gauge side-cut needles for ten core biopsy passes at a single academic hospital. Biopsy pass volume was then estimated in ex vivo porcine muscle, liver, and kidney using side-cut devices at 16, 18, and 20 gauge and end-cut devices at 16 and 18 gauge to estimate minimum number of passes required for adequate molecular testing. RESULTS: Molecular diagnostic adequacy increased from 69% (pre-implementation period) to 92% (post-implementation period) (p < 0.001) for lung biopsies. In porcine models, both 16-gauge end-cut and side-cut devices require one pass to reach the validated volume threshold to ensure 99% adequacy for molecular characterization, while 18- and 20-gauge devices require 2-5 passes depending on needle cut and tissue type. CONCLUSION: Use of 20-gauge side-cut core biopsy needles requires a significant number of passes to ensure diagnostic adequacy for molecular testing across all tissue types. To ensure diagnostic adequacy for molecular testing, 16- and 18-gauge needles require markedly fewer passes.

Percutaneous Renal Cryoablation: Short-Axis Ice-Ball Margin as a Predictor of Outcome.

PURPOSE: To determine if CT characteristics of intraprocedural ice balls correlate with outcomes after cryoablation. MATERIALS AND METHODS: A retrospective review was performed on 63 consecutive patients treated with renal cryoablation. Preprocedural and intraprocedural images were used to identify the size and location of renal tumors and ice balls as well as the tumor coverage and ice-ball margins. Review of follow-up imaging (1 mo and then 3-6-mo intervals) distinguished successful ablations from cases of residual tumor. RESULTS: Patients who underwent successful ablation (n = 50; 79%) had a mean tumor diameter of 2.5 cm (range, 0.9-4.3 cm) and mean ice-ball margin of 0.4 cm (range, 0.2-1.2 cm). Patients with residual tumor (n = 13; 21%) had a mean tumor diameter of 3.8 cm (range, 1.8-4.5 cm) and mean ice-ball margin of -0.4 cm (range, -0.9 to 0.4 cm). Residual and undertreated tumors were larger and had smaller ice-ball margins than successfully treated tumors (P < .01). Ice-ball diameters were significantly smaller after image reformatting (P < .01). Ice-ball margins of 0.15 cm had 90% sensitivity, 92% specificity, and 98% positive predictive value for successful ablation. Success was independent of tumor location or number of cryoprobes. CONCLUSIONS: Ice-ball margin and real-time intraprocedural reformatting could be helpful in predicting renal cryoablation outcomes. Although a 0.5-cm margin is preferred, a well-centered ice ball with a short-axis margin greater than 0.15 cm strongly correlated with successful ablation.

Magnetic Resonance-Monitored Coaxial Electrochemical Ablation--Preliminary Evaluation of Technical Feasibility.

PURPOSE: To evaluate the technical feasibility of a coaxial electrode configuration to rapidly create a mechanically defined electrochemical ablation zone monitored by magnetic resonance (MR) imaging in real time. MATERIALS AND METHODS: A direct current generator supplied the nitinol cathode cage and central platinum anode for coaxial electrochemical ablation. Safety and efficacy were evaluated by measuring local pH, temperature, and current scatter in saline solutions. Ablation zone diameters of 3-6 cm (n = 72) were created on ex vivo bovine liver and verified by gross pathology. Feasibility of MR monitoring was evaluated using 8 swine livers to create ablations of 3 cm (n = 12), 4 cm (n = 4), and 5 cm (n = 4) verified by histology. RESULTS: Local pH was 3.2 at the anode and 13.8 at the cathode. Current scatter was negligible. Ablation progress increased relative to local ion concentration, and MR signal changes corresponded to histologic findings. In the ex vivo model, the times to achieve complete ablation were 15 minutes, 20 minutes, 35 minutes, and 40 minutes for diameters of 3 cm, 4 cm, 5 cm, and 6 cm, respectively. Ablation times for the in situ model were 15 minutes, 35 minutes, and 50 minutes for 3 cm, 4 cm, and 5 cm, respectively. CONCLUSIONS: The coaxial configuration mechanically defined the electrochemical ablation zone with times similar to comparably sized thermal ablations. MR compatibility allowed for real-time monitoring of ablation progress.

Iatrogenic percutaneous vascular injuries: clinical presentation, imaging, and management.

Vascular interventional radiology procedures are relatively safe compared with analogous surgical procedures, with overall major complication rates of less than 1%. However, major vascular injuries resulting from these procedures may lead to significant morbidity and mortality. This review will discuss the etiology, clinical presentation, diagnosis, and management of vascular complications related to percutaneous vascular interventions. Early recognition of these complications and familiarity with treatment options are essential skills for the interventional radiologist.

Retrieval of Tip-embedded Inferior Vena Cava Filters by Using the Endobronchial Forceps Technique: Experience at a Single Institution.

PURPOSE: To evaluate the use of endobronchial forceps to retrieve tip-embedded inferior vena cava (IVC) filters. MATERIALS AND METHODS: This institutional review board-approved, HIPAA-compliant retrospective study included 114 patients who presented with tip-embedded IVC filters for removal from January 2005 to April 2014. The included patients consisted of 77 women and 37 men with a mean age of 43 years (range, 18-79 years). Filters were identified as tip embedded by using rotational venography. Rigid bronchoscopy forceps were used to dissect the tip or hook of the filter from the wall of the IVC. The filter was then removed through the sheath by using the endobronchial forceps. Statistical analysis entailed calculating percentages, ranges, and means. RESULTS: The endobronchial forceps technique was used to successfully retrieve 109 of 114 (96%) tip-embedded IVC filters on an intention-to-treat basis. Five failures occurred in four patients in whom the technique was attempted but failed and one patient in whom retrieval was not attempted. Filters were in place for a mean of 465 days (range, 31-2976 days). The filters in this study included 10 Recovery, 33 G2, eight G2X, 11 Eclipse, one OptEase, six Option, 13 Günther Tulip, one ALN, and 31 Celect filters. Three minor complications and one major complication occurred, with no permanent sequelae. CONCLUSION: The endobronchial forceps technique can be safely used to remove tip-embedded IVC filters.

Diagnostic role of Gallium-68 DOTATOC and Gallium-68 DOTATATE PET in patients with neuroendocrine tumors: a meta-analysis.

BACKGROUND: Gallium-68 somatostatin receptor positron emission tomography (PET) has been used in the diagnosis of neuroendocrine tumors (NETs). The compounds often used in molecular imaging of NETs with PET are 68Ga-DOTATOC, 68Ga-DOTATATE, and 68Ga-DOTANOC. There is varying affinity to different somatostatin receptors. PURPOSE: To systematically review and perform a meta-analysis of published data regarding the diagnostic role of 68Ga-DOTATOC and 68Ga-DOTATATE PET in the diagnosis of NETs. MATERIAL AND METHODS: A comprehensive literature search of studies published through 30 April 2013 regarding 68Ga-DOTATOC and 68Ga-DOTATATE PET in the diagnosis of NETs was performed using the PubMed/MEDLINE, Embase, and Scopus databases. Pooled sensitivity and specificity of 68Ga-DOTATOC and 68Ga-DOTATATE PET in the diagnosis of NETs were calculated. The area under the receiver-operating characteristic (ROC) curve was calculated to measure the accuracy of 68Ga-DOTATOC and 68Ga-DOTATATE PET in the diagnosis of NETs. RESULTS: Ten studies comprising 416 patients with NETs were included in this meta-analysis. The pooled sensitivity of 68Ga-DOTATOC and 68Ga-DOTATATE PET in the diagnosis of NETs calculated on a per-patient-based analysis was 93% (95% confidence interval [CI] 89-96%) and 96% (95% CI 91-99%). The pooled specificity of 68Ga-DOTATOC and 68Ga-DOTATATE PET in diagnosing NETs was 85% (95% CI 74-93%) and 100% (95% CI 82-100%). The area under the ROC curve of 68Ga-DOTATOC and 68Ga-DOTATATE PET was 0.96 and 0.98, respectively, on a per-patient-based analysis. CONCLUSION: The molecular imaging agents 68Ga-DOTATOC and 68Ga-DOTATATE demonstrated high sensitivity and specificity in the diagnosis of NETs on PET scan. Although both are accurate tools in the diagnosis of NETs, 68Ga-DOTATATE PET may be more sensitive and specific than 68Ga-DOTATOC PET scan.

The application of SPECT/CT for preoperative planning in patients with secondary hyperparathyroidism.

BACKGROUND AND PURPOSE: Secondary hyperparathyroidism (SHPT) is a frequent and challenging issue in patients undergoing dialysis for chronic kidney disease. Surgical intervention in the form of parathyroidectomy is generally considered only in cases of severe SHPT. However, identification of the exact location of the parathyroid glands (PTGs) before parathyroidectomy is a challenge. The aim of this study was to evaluate the role of 99mTc sestamibi single-photon emission computed tomography (SPECT)/computed tomography (CT) in the detection of parathyroids to guide operative therapy in patients with SHPT. PATIENTS AND METHODS: Ninety patients with SHPT who were on hemodialysis were evaluated preoperatively with double-phase 99mTc sestamibi static planar and SPECT/CT parathyroid scintigraphy to evaluate for parathyroids before parathyroidectomy. The sensitivity, specificity, and accuracy of 99mTc sestamibi static planar and SPECT/CT scintigraphy were determined. RESULTS: Compared with static planar scintigraphy, 99mTc sestamibi SPECT/CT was able to detect a larger number of PTGs per study, as well as PTGs of smaller diameter and PTGs of smaller size. The sensitivity, specificity, and accuracy of 99mTc sestamibi SPECT/CT in detecting PTGs were 78.9, 100, and 78.9%, respectively, compared with 55.6, 100, and 55.6% for static planar 99mTc sestamibi. CONCLUSION: Our study indicates that 99mTc sestamibi SPECT/CT has a higher sensitivity compared with static planar scintigraphy in the preoperative evaluation of hemodialysis patients with SHPT because of chronic kidney disease. SPECT/CT can not only detect a larger number of PTGs but can also depict the precise location of PTGs more accurately when compared with static planar scintigraphy.