Early Clinical Feasibility Evaluation of an Augmented Reality Platform for Guidance and Navigation during Percutaneous Tumor Ablation.

An augmented reality platform with a head-mounted display and electromagnetic tracking of instruments was developed for percutaneous procedural guidance. Earlier work had demonstrated bench and first-in-human feasibility of the platform. This report further evaluated the clinical usability and benefits of this technology. The platform was used in 12 patients who had been referred for percutaneous thermal ablation of abdominal soft tissue tumors. In 10 cases, the intraprocedural holographic guidance agreed with the standard imaging guidance. The evaluation was limited in 2 cases because of anatomic and workflow issues. Overall, this series demonstrated the clinical feasibility of this platform and the potential benefits of its use in percutaneous procedures.

Hepatic Venous Pressure Gradient Measurements in Children: Correlation With Hepatic Histology and Clinical Indicators of Portal Hypertension.

OBJECTIVES: In adults, elevated hepatic venous pressure gradients (HVPGs) are correlated with the degree of liver fibrosis on histopathology and predict worse outcomes including variceal bleeding and death. We aimed to examine the association between HVPG measurements, histopathologic findings, and clinical indicators of portal hypertension in children. METHODS: Utilizing retrospective data from 2 pediatric centers between 2006 and 2015, we identified children who underwent simultaneous HVPG measurement and transjugular liver biopsy. Medical charts were reviewed for histopathology, imaging, endoscopic, and clinical data. RESULTS: Forty-one children (median age 11 years) were included in the analysis with diagnoses of acute hepatitis (n = 15), chronic liver disease (n = 12), hepatic noncirrhotic portal hypertension (n = 4), acute liver failure (n = 3), and nonhepatic causes of portal hypertension (n = 7). Elevated mean HVPG measurements were found in children with acute liver failure (10 mmHg, range 4-12) and chronic liver disease (7 mmHg, range 1-12). HVPG measurements did not correlate with the histological severity of fibrosis (ρ = 0.23, P = 0.14) or portal inflammation (ρ = 0.24, P = 0.29), and no difference was found in HVPG when comparing children with and without a history of variceal bleeding (P = 0.43). CONCLUSIONS: HVPG measurements do not correlate significantly with the degree of hepatic fibrosis on biopsy. Furthermore, HVPG measurements are not associated with the presence of varices or history of variceal bleeding, suggesting the possibility of intrahepatic shunting in children with advanced liver disease. Therefore, unlike in adults, HVPG measurements may not accurately predict children who are at risk of complications from portal hypertension.

Presenting Symptoms and Dysphagia Screen Predict Outcome in Mild and Rapidly Improving Acute Ischemic Stroke Patients.

OBJECTIVE: There are limited data on which patients not treated with intravenous (IV) tissue-type plasminogen activator (tPA) due to mild and rapidly improving stroke symptoms (MaRISS) have unfavorable outcomes. MATERIALS AND METHODS: Acute ischemic stroke (AIS) patients not treated with IV tPA due to MaRISS from January 1, 2009 to December 31, 2013 were identified as part of the Georgia Coverdell Acute Stroke Registry. Multivariable regression analysis was used to identify factors associated with a lower likelihood of favorable outcome, defined as discharge to home. RESULTS: There were 1614 AIS patients who did not receive IV tPA due to MaRISS (median National Institutes of Health stroke scale [NIHSS] 1], of which 305 (19%) did not have a favorable outcome. Factors associated with lower likelihood of favorable outcome included Medicare insurance status (odds ratio [OR]: .53, 95% confidence interval [CI]: .34-.84), arrival by emergency medical services (OR: .46, 95% CI: .29-.73), increasing NIHSS score (per unit OR: .89, 95% CI: .84-.93), weakness as the presenting symptom (OR: .50, 95% CI: .30-.84), and a failed dysphagia screen (OR: .43, 95% CI: .23-.80). During the study period, <1% of patients presenting to participating hospitals with MaRISS within the eligible time window received IV tPA. CONCLUSIONS: Baseline characteristics, presenting symptoms, and response to dysphagia screen identify a subgroup of patients who are more likely to have an unfavorable outcome. Whether IV tPA treatment can improve the outcome in this subgroup of patients needs to be evaluated in a randomized placebo-controlled trial.

Evaluation of an augmented reality navigational guidance platform for percutaneous procedures in a cadaver model.

Purpose: The objective of this study is to review the accuracy of an augmented reality navigational guidance system designed to facilitate improved visualization, guidance, and accuracy during percutaneous needle-based procedures including biopsies and ablations. Approach: Using the HoloLens 2, the system registers and projects 3D CT-based models of segmented anatomy along with live ultrasound, fused with electromagnetically tracked instruments including ultrasound probes and needles, giving the operator comprehensive stereoscopic visualization for intraoperative planning and navigation during procedures.Tracked needles were guided to targets implanted in a cadaveric model using the system. Image fusion registration error, the multimodality error measured as the post-registration distance between a corresponding point measured in the stereoscopic CT and tracked ultrasound coordinate systems, and target registration error, the Euclidean distance between needle tip and target after needle placement, were measured as registration and targeting accuracy metrics. A t-distribution was used for statistical analysis. Results: Three operators performed 36 total needle passes, 18 to measure image fusion registration error and 18 to measure target registration error on four targets. The average depth of each needle pass was 8.4 cm from skin to target center. Mean IFRE was 4.4 mm (H0: µ=5 mm, P<0.05). Mean TRE was 2.3 mm (H0: µ=5 mm, P<0.00001). Conclusions: The study demonstrated high registration and targeting accuracy of this AR navigational guidance system in percutaneous, needle-based procedures. This suggests the ability to facilitate improved clinical performance in percutaneous procedures such as ablations and biopsies.

Frequency of and Factors Associated With Obstructive Sleep Apnea and Periodic Limb Movements in Stroke and TIA Patients.

INTRODUCTION: Obstructive sleep apnea (OSA) and periodic limb movements (PLMs) have been associated with an increased risk of cardiovascular disease. There is limited data on the relationship between OSA and PLMs with atrial fibrillation and resistant hypertension in stroke and transient ischemic attack (TIA) patients. METHODS: Consecutive stroke and TIA patients referred by a vascular neurologist for diagnostic polysomnography (PSG) from September 1, 2012 to August 31, 2015 were included in a retrospective analysis. Baseline clinical characteristics, PSG results and outcomes were collected to identify the frequency of and factors associated with PLMs (mild 5 to 10/h; severe ≥15/h), PLM arousals (≥5/h) and moderate-severe OSA (apna-hypopnea Index ≥15) including atrial fibrillation and resistant hypertension. RESULTS: Among 103 patients (mean age, 60±15 y; 50% female; 61% nonwhites; 77% ischemic stroke; 23% resistant hypertension) who underwent PSG, 20% had mild PLMs, 28% had severe PLMs, 14% had PLM arousals, and 22% had moderate-severe OSA. Factors associated with moderate-severe OSA included older age (odds ratio, 1.06; 95% confidence interval, 1.02-1.11) and presence of atrial fibrillation (odds ratio, 4.26; 95% confidence interval, 1.17-15.44). Nonwhite race was associated with lower likelihood of mild and severe PLMs, whereas female sex was associated with lower likelihood of PLM arousals. OSA and PLMs were not associated with resistant hypertension. CONCLUSIONS: A significant number of stroke and TIA patients who underwent PSG have PLMs and moderate-severe OSA. Stroke and TIA patients with atrial fibrillation are more likely to have moderate-severe OSA and may benefit from PSG evaluation.