Mixed reality in interventional radiology: a focus on first clinical use of XR90 augmented reality-based visualization and navigation platform.

INTRODUCTION: Augmented reality (AR) and virtual reality (VR) are emerging tools in interventional radiology (IR), enhancing IR education, preprocedural planning, and intraprocedural guidance. AREAS COVERED: This review identifies current applications of AR/VR in IR, with a focus on studies that assess the clinical impact of AR/VR. We outline the relevant technology and assess current limitations and future directions in this space. We found that the use of AR in IR lags other surgical fields, and the majority of the data exists in case series or small-scale studies. Educational use of AR/VR improves learning anatomy, procedure steps, and procedural learning curves. Preprocedural use of AR/VR decreases procedure times, especially in complex procedures. Intraprocedural AR for live tracking is accurate within 5 mm live patients and has up to 0.75 mm in phantoms, offering decreased procedure time and radiation exposure. Challenges include cost, ergonomics, rapid segmentation, and organ motion. EXPERT OPINION: The use of AR/VR in interventional radiology may lead to safer and more efficient procedures. However, more data from larger studies is needed to better understand where AR/VR is confers the most benefit in interventional radiology clinical practice.

Systematic Review of Use of Patient-Reported Outcomes in Interventional Radiology.

INTRODUCTION: A patient-reported outcome (PRO) is any outcome reported directly by the patient, in contradistinction to a clinician-reported outcomes, which have dominated clinical research. This systematic review evaluates the ways in which PROs have been used in the interventional radiology literature. METHODS: Systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was designed and conducted by a medical librarian. Studies were screened for inclusion by two independent members, with a third member as a conflict resolver. The data were extracted from each study in a consistent and structured manner. RESULTS: In all, 354 studies met criteria for full-text analysis; 218 of 354 (62%) used a prospective design and most frequently provided level III (249 of 354, 70%) or level I (68 of 354, 19%) evidence. The manner in which PROs were obtained was reported in 125 of 354 (35%) of studies. Questionnaire response rate was documented in 51 of 354 (14%) studies, and questionnaire completion rate was documented in 49 of 354 (14%) studies. Of 354 studies, 281 (79%) studies used at least one independently validated questionnaire. The disease domains most commonly assessed via PRO were women's health (62 of 354, 18%) and men's health (60 of 354, 17%). DISCUSSION: Wider development, validation, and systematic use of PROs in IR would enable more informed patient-centered decision making. A greater focus on PROs in clinical trials would elucidate expected outcomes from the patient's perspective, simplifying comparisons with therapeutic alternatives. To produce more convincing evidence, trials must apply validated PROs rigorously and report possible confounding factors consistently.

Dynamic Measurement of Arterial Liver Perfusion With an Interventional C-Arm System.

PURPOSE: Objective intraprocedural measurement of hepatic blood flow could provide a quantitative treatment end point for locoregional liver procedures. This study aims to validate the accuracy and reproducibility of cone-beam computed tomography perfusion (CBCTp) measurements of arterial liver perfusion (ALP) against clinically available computed tomography perfusion (CTp) measurements in a swine embolization model. METHODS: Triplicate CBCTp measurements using a selective arterial contrast injection were performed before and after complete embolization of the left lobe of the liver in 5 swine. Two CBCTp protocols were evaluated that differed in sweep duration (3.3 vs 4.5 seconds) and the number of acquired projection images (166 vs 248). The mean ALP was measured within identical volumes of interest selected in the embolized and nonembolized regions of the perfusion map generated from each scan. Postembolization CBCTp values were also compared with CTp measurements. RESULTS: The 2 CBCTp protocols demonstrated high concordance correlation (0.90, P < 0.001). Both CBCTp protocols showed higher reproducibility than CTp in the nontarget lobe, with an intraclass correlation of 0.90 or greater for CBCTp and 0.83 for CTp (P < 0.001 for all correlations). The ALP in the embolized lobe was nearly zero and hence excluded for reproducibility. High concordance correlation was observed between the CTp and each CBCTp protocol, with the shorter CBCTp protocol reaching a concordance correlation of 0.75 and the longer achieving 0.87 (P < 0.001 for both correlations). CONCLUSIONS: Dynamic blood flow measurement using an angiographic C-arm system is feasible and produces quantitative results comparable to CTp.

The Role of Dual-Phase Cone-Beam CT in Predicting Short-Term Response after Transarterial Chemoembolization for Hepatocellular Carcinoma.

PURPOSE: To identify computational and qualitative features derived from dual-phase cone-beam CT that predict short-term response in patients undergoing transarterial chemoembolization for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: This retrospective study included 43 patients with 59 HCCs. Six features were extracted, including intensity of tumor enhancement on both phases and characteristics of the corona on the washout phase. Short-term response was evaluated by modified Response Evaluation Criteria in Solid Tumors on follow-up imaging, and extracted features were correlated to response using univariate and multivariate analyses. RESULTS: Univariate and multivariate analyses did not reveal a correlation between absolute and relative tumor enhancement characteristics on either phase with response (arterial P = .21; washout P = .40; ∆ P = .90). On multivariate analysis of qualitative characteristics, the presence of a diffuse corona was an independent predictor of incomplete response (P = .038) and decreased the odds ratio of objective response by half regardless of tumor size. CONCLUSIONS: Computational features extracted from contrast-enhanced dual-phase cone-beam CT are not prognostic of response to transarterial chemoembolization in patients with HCC. HCCs that demonstrate a diffuse, patchy corona have reduced odds of achieving complete response after transarterial chemoembolization and should be considered for additional treatment with an alternative modality.

Accuracy of flat panel detector CT with integrated navigational software with and without MR fusion for single-pass needle placement.

PURPOSE: Fluoroscopic systems in modern interventional suites have the ability to perform flat panel detector CT (FDCT) with navigational guidance. Fusion with MR allows navigational guidance towards FDCT occult targets. We aim to evaluate the accuracy of this system using single-pass needle placement in a deep brain stimulation (DBS) phantom. MATERIALS AND METHODS: MR was performed on a head phantom with DBS lead targets. The head phantom was placed into fixation and FDCT was performed. FDCT and MR datasets were automatically fused using the integrated guidance system (iGuide, Siemens). A DBS target was selected on the MR dataset. A 10 cm, 19 G needle was advanced by hand in a single pass using laser crosshair guidance. Radial error was visually assessed against measurement markers on the target and by a second FDCT. Ten needles were placed using CT-MR fusion and 10 needles were placed without MR fusion, with targeting based solely on FDCT and fusion steps repeated for every pass. RESULTS: Mean radial error was 2.75±1.39 mm as defined by visual assessment to the centre of the DBS target and 2.80±1.43 mm as defined by FDCT to the centre of the selected target point. There were no statistically significant differences in error between MR fusion and non-MR guided series. CONCLUSIONS: Single pass needle placement in a DBS phantom using FDCT guidance is associated with a radial error of approximately 2.5-3.0 mm at a depth of approximately 80 mm. This system could accurately target sub-centimetre intracranial lesions defined on MR.

Involvement of oxidative stress and caspase 2-mediated intrinsic pathway signaling in age-related increase in muscle cell apoptosis in mice.

Apoptosis has been implicated as a mechanism of loss of muscle cells in normal aging and plays an important role in age-related sarcopenia. To test the hypothesis that caspase 2 and c-Jun NH(2)-terminal kinase (JNK)-mediated intrinsic pathway signaling contribute to skeletal muscle cell apoptosis in aging, we compared activation of caspase 2 and JNK and the in vivo expression of 4-hydroxynonenal protein adducts (4-HNE), inducible nitric oxide synthase (iNOS), glucose-6-phosphate dehydrogenase (G6PDH), B-cell lymphoma-2 (BCL-2), BAX, and phospho-BCL-2 in gastrocnemius muscles of young (5 months old) and old (25 months old) mice. A distinct age-related increase in 4-HNE and iNOS expression was readily detected in mice. Increased oxidative stress and iNOS induction were further accompanied by a decrease in G6PDH expression, activation of caspase 2 and JNK, and inactivation of BCL-2 through phosphorylation at serine 70, and caspase 9 activation. Regression analysis further revealed that increased muscle cell death in aging was significantly correlated with changes in the levels of these molecules. Taken together, our data indicate that caspase 2 and JNK-mediated intrinsic pathway signaling is one of the mechanisms involved in age-related increase in muscle cell apoptosis.