ObjectA new method for 3D localization of N fiducial markers from 1D projections is presented and analysed. It applies to semi-active markers and active markers using a single receiver channel.Materials and methodsThe novel algorithm computes candidate points using peaks in three optimally selected projections and removes fictitious points by verifying detected peaks in additional projections. Computational complexity was significantly reduced by avoiding cluster analysis, while higher accuracy was achieved by using optimal projections and by applying Gaussian interpolation in peak detection. Computational time, accuracy and robustness were analysed through Monte Carlo simulations and experiments. The method was employed in a prototype MRI guided prostate biopsy system and used in preclinical experiments.ResultsThe computational time for 6 markers was better than 2 ms, an improvement of up to 100 times, compared to the method by Flask et al. (J Magn Reson Imaging 14(5):617–627, 2001). Experimental maximum localization error was lower than 0.3 mm; standard deviation was 0.06 mm. Targeting error was about 1 mm. Tracking update rate was about 10 Hz.ConclusionThe proposed method is particularly suitable in systems requiring any of the following: high frame rate, tracking of three or more markers, data filtering or interleaving.

Work from our laboratory documents pathological events, including myofiber oxidative damage and degeneration, myofibrosis, micro-vessel (diameter = 50–150 μm) remodeling, and collagenous investment of terminal micro-vessels (diameter ≤ 15 µm) in the calf muscle of patients with Peripheral Artery Disease (PAD). In this study, we evaluate the hypothesis that the vascular pathology associated with the legs of PAD patients encompasses pathologic changes to the smallest micro-vessels in calf muscle. Biopsies were collected from the calf muscle of control subjects and patients with Fontaine Stage II and Stage IV PAD. Slide specimens were evaluated by Quantitative Multi-Spectral and Fluorescence Microscopy. Inter-myofiber collagen, stained with Masson Trichrome (MT), was increased in Stage II patients, and more substantially in Stage IV patients in association with collagenous thickening of terminal micro-vessel walls. Evaluation of the Basement Membrane (BM) of these vessels reveals increased thickness in Stage II patients, and increased thickness, diameter, and Collagen I deposition in Stage IV patients. Coverage of these micro-vessels with pericytes, key contributors to fibrosis and BM remodeling, was increased in Stage II patients, and was greatest in Stage IV patients. Vascular pathology of the legs of PAD patients extends beyond atherosclerotic main inflow arteries and affects the entire vascular tree—including the smallest micro-vessels.

Background: Central-line–associated bloodstream infections (CLABSIs) result in increased patient morbidity. Guidelines recommend against peripheral venous catheters when access is required for longer than 6 days, often leading to central venous catheter (CVC) placement. To improve vascular access device choice and reduce the potential risk of CLABSI, we implemented a quality improvement initiative comprised of a vascular access algorithm and introduction of a midline vascular access device (MVAD). We report complications associated with MVAD use including deep vein thrombosis (DVT), thrombophlebitis, and BSI. Methods: A prospective quality improvement assessment from October 2017 through March 2018. All MVADs were monitored for DVT, thrombophlebitis, and BSI. Insertion time and removal of MVAD were tracked, as well as presence of other vascular access devices. Results: From October 2017 through March 2018, 858 MVADs were inserted in 726 different patients, yielding 3,588 MVD days. In total, 6 primary BSIs occurred in patients with MVADs. In patients with only a MVAD, the rate was 0.72 BSI per 1,000 MVAD days, whereas patients with an MVAD as well as a CVC had a rate of 1.98 per 1,000 MVAD days. The overall CLABSI rate at the institution during this period of time was 1.24 per 1,000 CVC days. Also, 29 cases of thrombophlebitis occurred, for a rate of 3.84 per 1,000 catheter days in patients with only an MVAD compared to 4.63 per 1,000 catheter days in patients with an MVAD and a CVC. Also, 25 DVTs occurred during this time, resulting in a rate of 2.88 per 1,000 catheter days in patients with only an MVAD and 4.63 per 1,000 catheter days in patients with multiple vascular-access devices. A significant correlation was noted between MVAD indwell time and BSI (P = .0021) and thrombophlebitis (P = .0041). The median indwell time for patients experiencing BSI was 16.17 days ± 8.04 days, whereas the median indwell time for patients experiencing thrombophlebitis was 9.24 days ± 7.99 days. Conclusions: The implementation of a vascular-access algorithm including MVAD may effectively reduce CVC insertions and BSIs. The rate of BSI in MVAD was below that of CLABSI during the assessment period. Known complications associated with MVAD include DVTs and thrombophlebitis, which correlates with the duration of catheterization, and these risks appear to be further compounded in patients requiring multiple devices for vascular access. Further research into comparing the risk of vascular access of MVAD with CVC is warranted.Funding: NoneDisclosures: None

Objectives: This report evaluates the safety of percutaneous mechanical thrombectomy with the Inari FlowTriever System (Inari Medical, Irvine, California) for the treatment of acute massive/submassive pulmonary embolism (PE) specifically in therapeutically anticoagulated patients with contraindication to thrombolysis. Material and Methods: A single-center retrospective chart review was performed on patients with contraindication to thrombolysis and massive/submassive PE who underwent FlowTriever thrombectomy between 2017 and 2019. Primary outcomes included procedure or device-related complications within 30 days of discharge. Secondary outcomes included technical and clinical success defined by improvement in mean pulmonary artery pressure (PAP), oxygen saturation, and heart rate. Results: Thirteen patients with contraindication to thrombolysis received FlowTriever thrombectomy with technical success achieved in all cases. Zero major or minor adverse events, technical complications, delayed procedure-related complications, or deaths within 30 days of hospital discharge occurred. Mean PAP decreased significantly by 19.1% (32.5 ± 13.3 mmHg to 26.3 ± 12.4 mmHg; P = 0.0074, 95% confidence interval (CI) 2.0–10.5 mmHg). Oxygen saturation improved post-procedure (increased 3.9 ± 3.8%; p = 0.0032, 95% CI 1.6– 6.1%) as did heart rate (decreased 22.2 ± 17.0 bpm; P < 0.001, 95% CI 11.9–32.4 bpm). Anticoagulation was maintained throughout every procedure and all patients were closed with purse-string suture only. Conclusion: FlowTriever mechanical thrombectomy appears safe for acute PE in therapeutically anticoagulated patients with contraindications to thrombolytic therapy. These patients may experience immediate hemodynamic improvements similar to those reported in other studies. Further data are needed to prospectively evaluate long-term safety in this population.

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