Feasibility of multi-section continuum robotic ureteroscope in the kidney.

Our objective was to evaluate the feasibility of a multi-section continuum robotic ureteroscope to address the difficulties with access into certain renal calyces during flexible ureteroscopy. First, the robotic ureteroscope developed in previous research, which utilizes three actuated bendable sections controlled by wires, was modified for use in this project. Second, using phantom models created from five randomly selected computer tomography urograms, the flexible ureteroscope and robotic ureteroscope were evaluated, focusing on several factors: time taken to access each renal calyx, time taken to aim at three targets on each renal calyx, the force generated in the renal pelvic wall associated with ureteroscope manipulation, and the distance and standard deviation between the ureteroscope and the target. As a result, the robotic ureteroscope utilized significantly less force during lower pole calyx access (flexible ureteroscope vs. robotic ureteroscope; 2.0 vs. 0.98 N, p = 0.03). When aiming at targets, the standard deviation of proper target access was smaller for each renal calyx (upper pole: 0.49 vs. 0.11 mm, middle: 0.84 vs. 0.12 mm, lower pole: 3.4 vs. 0.19 mm) in the robotic ureteroscope group, and the distance between the center point of the ureteroscope image and the target was significantly smaller in the robotic ureteroscope group (upper: 0.49 vs. 0.19 mm, p < 0.001, middle: 0.77 vs. 0.17 mm, p < 0.001, lower: 0.77 vs. 0.22 mm, p < 0.001). In conclusion, our robotic ureteroscope demonstrated improved maneuverability and facilitated accuracy and precision while reducing the force on the renal pelvic wall during access into each renal calyx.

Computer-based airway stenosis quantification from bronchoscopic images: preliminary results from a feasibility trial.

PURPOSE: Airway Stenosis (AS) is a condition of airway narrowing in the expiration phase. Bronchoscopy is a minimally invasive pulmonary procedure used to diagnose and/or treat AS. The AS quantification in a form of the Stenosis Index (SI), whether subjective or digital, is necessary for the physician to decide on the most appropriate form of treatment. The literature reports that the subjective SI estimation is inaccurate. In this paper, we propose an approach to quantify the SI defining the level of airway narrowing, using depth estimation from a bronchoscopic image. METHODS: In this approach we combined a generative depth estimation technique combined with depth thresholding to provide Computer-based AS quantification. We performed an interim clinical analysis by comparing AS quantification performance of three expert bronchoscopists against the proposed Computer-based method on seven patient datasets. RESULTS: The Mean Absolute Error of the subjective Human-based and the proposed Computer-based SI estimation was [Formula: see text] [%] and [Formula: see text] [%], respectively. The correlation coefficients between the CT measurements were used as the gold standard, and the Human-based and Computer-based SI estimation were [Formula: see text] and 0.46, respectively. CONCLUSIONS: We presented a new computer method to quantify the severity of AS in bronchoscopy using depth estimation and compared the performance of the method against a human-based approach. The obtained results suggest that the proposed Computer-based AS quantification is a feasible tool that has the potential to provide significant assistance to physicians in bronchoscopy.

Predicting reachability to peripheral lesions in transbronchial biopsies using CT-derived geometrical attributes of the bronchial route.

PURPOSE: The bronchoscopist's ability to locate the lesion with the bronchoscope is critical for a transbronchial biopsy. However, much less study has been done on the transbronchial biopsy route. This study aims to determine whether the geometrical attributes of the bronchial route can predict the difficulty of reaching tumors in bronchoscopic intervention. METHODS: This study included patients who underwent bronchoscopic diagnosis of lung tumors using electromagnetic navigation. The biopsy instrument was considered "reached" and recorded as such if the tip of the tracked bronchoscope or extended working channel was in the tumors. Four geometrical indices were defined: Local curvature (LC), plane rotation (PR), radius, and global relative angle. A Mann-Whitney U test and logistic regression analysis were performed to analyze the difference in geometrical indices between the reachable and unreachable groups. Receiver operating characteristic analysis (ROC) was performed to evaluate the geometrical indices to predict reachability. RESULTS: Of the 41 patients enrolled in the study, 16 patients were assigned to the unreachable group and 25 patients to the reachable group. LC, PR, and radius have significantly higher values in unreachable cases than in reachable cases ([Formula: see text], [Formula: see text], [Formula: see text]). The logistic regression analysis showed that LC and PR were significantly associated with reachability ([Formula: see text], [Formula: see text]). The areas under the curve with ROC analysis of the LC and PR index were 0.903 and 0.618. The LC's cut-off value was 578.25. CONCLUSION: We investigated whether the geometrical attributes of the bronchial route to the lesion can predict the difficulty of reaching the lesions in the bronchoscopic biopsy. LC, PR, and radius have significantly higher values in unreachable cases than in reachable cases. LC and PR index can be potentially used to predict the navigational success of the bronchoscope.

Visually Navigated Bronchoscopy using three cycle-Consistent generative adversarial network for depth estimation.

[Background] Electromagnetically Navigated Bronchoscopy (ENB) is currently the state-of-the art diagnostic and interventional bronchoscopy. CT-to-body divergence is a critical hurdle in ENB, causing navigation error and ultimately limiting the clinical efficacy of diagnosis and treatment. In this study, Visually Navigated Bronchoscopy (VNB) is proposed to address the aforementioned issue of CT-to-body divergence. [Materials and Methods] We extended and validated an unsupervised learning method to generate a depth map directly from bronchoscopic images using a Three Cycle-Consistent Generative Adversarial Network (3cGAN) and registering the depth map to preprocedural CTs. We tested the working hypothesis that the proposed VNB can be integrated to the navigated bronchoscopic system based on 3D Slicer, and accurately register bronchoscopic images to pre-procedural CTs to navigate transbronchial biopsies. The quantitative metrics to asses the hypothesis we set was Absolute Tracking Error (ATE) of the tracking and the Target Registration Error (TRE) of the total navigation system. We validated our method on phantoms produced from the pre-procedural CTs of five patients who underwent ENB and on two ex-vivo pig lung specimens. [Results] The ATE using 3cGAN was 6.2 +/- 2.9 [mm]. The ATE of 3cGAN was statistically significantly lower than that of cGAN, particularly in the trachea and lobar bronchus (p < 0.001). The TRE of the proposed method had a range of 11.7 to 40.5 [mm]. The TRE computed by 3cGAN was statistically significantly smaller than those computed by cGAN in two of the five cases enrolled (p < 0.05). [Conclusion] VNB, using 3cGAN to generate the depth maps was technically and clinically feasible. While the accuracy of tracking by cGAN was acceptable, the TRE warrants further investigation and improvement.

Technical Validation of Multi-Section Robotic Bronchoscope With First Person View Control for Transbronchial Biopsies of Peripheral Lung.

This study aims to validate the advantage of new engineering method to maneuver multi-section robotic bronchoscope with first person view control in transbronchial biopsy. Six physician operators were recruited and tasked to operate a manual and a robotic bronchoscope to the peripheral area placed in patient-derived lung phantoms. The metrics collected were the furthest generation count of the airway the bronchoscope reached, force incurred to the phantoms, and NASA-Task Load Index. The furthest generation count of the airway the physicians reached using the manual and the robotic bronchoscopes were 6.6 ±1.2th and 6.7 ±0.8th. Robotic bronchoscopes successfully reached the 5th generation count into the peripheral area of the airway, while the manual bronchoscope typically failed earlier in the 3 rd generation. More force was incurred to the airway when the manual bronchoscope was used ( 0.24 ±0.20 [N]) than the robotic bronchoscope was applied ( 0.18 ±0.22 [N], ). The manual bronchoscope imposed more physical demand than the robotic bronchoscope by NASA-TLX score ( 55 ±24 vs 19 ±16, ). These results indicate that a robotic bronchoscope facilitates the advancement of the bronchoscope to the peripheral area with less physical demand to physician operators. The metrics collected in this study would expect to be used as a benchmark for the future development of robotic bronchoscopes.

Transbronchial biopsy catheter enhanced by a multisection continuum robot with follow-the-leader motion.

PURPOSE: Current manual catheters for transbronchial biopsy in the lung lack a steering ability, which hampers a physician's ability to reach nodules in the peripheral lung. The objective of this paper is to design and build a multisection robot with a follow-the-leader motion and compare the performance of the conventional catheter and our robotic catheter in the right main and right segmental lobar bronchus. METHODS: A three-section continuum robot with an outer diameter of 3 mm was developed. Each section includes one anchored wire and two driving wires made of stainless steel. Follow-the-leader control is implemented using a joystick for a physician to control the distal section of the robot, while the subsequent two sections follow the controlled distal section. RESULTS: The robotic catheter deviated from the preplanned approach path by less than the manual catheter did (robotic: [Formula: see text] mm and manual: [Formula: see text] mm), with [Formula: see text]. The average force applied to the wall, producing potential trauma to the wall, was less for the robotic catheter ([Formula: see text] N) than for the manual catheter ([Formula: see text] N), [Formula: see text]. CONCLUSION: This study demonstrated an improvement in the maneuverability for the robotic catheter. In addition to a greater aptitude for reaching a peripheral area of the lung, these findings suggest that the designated target in a peripheral area can be reached with less trauma to the bronchi wall.

Analysis of longitudinal diffusion-weighted images in healthy and pathological aging: An ADNI study.

BACKGROUND & NEW METHOD: The widely used framework of voxel-based morphometry for analyzing neuroimages is extended here to model longitudinal imaging data by exchanging the linear model with a linear mixed-effects model. The new approach is employed for analyzing a large longitudinal sample of 756 diffusion-weighted images acquired in 177 subjects of the Alzheimer's Disease Neuroimaging initiative (ADNI). RESULTS AND COMPARISON WITH EXISTING METHODS: While sample- and group-level results from both approaches are equivalent, the mixed-effect model yields information at the single subject level. Interestingly, the neurobiological relevance of the relevant parameter at the individual level describes specific differences associated with aging. In addition, our approach highlights white matter areas that reliably discriminate between patients with Alzheimer's disease and healthy controls with a predictive power of 0.99 and include the hippocampal alveus, the para-hippocampal white matter, the white matter of the posterior cingulate, and optic tracts. In this context, notably the classifier includes a sub-population of patients with minimal cognitive impairment into the pathological domain. CONCLUSION: Our classifier offers promising features for an accessible biomarker that predicts the risk of conversion to Alzheimer's disease. Data used in preparation of this article were obtained from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database (adni.loni.usc.edu). As such, the investigators within the ADNI contributed to the design and implementation of ADNI and/or provided data but did not participate in analysis or writing of this report. A complete listing of ADNI investigators can be found at: http://adni.loni.usc.edu/wp-content/uploads/how to apply/ADNI Acknowledgement List.pdf. Significance statement This study assesses neuro-degenerative processes in the brain's white matter as revealed by diffusion-weighted imaging, in order to discriminate healthy from pathological aging in a large sample of elderly subjects. The analysis of time-series examinations in a linear mixed effects model allowed the discrimination of population-based aging processes from individual determinants. We demonstrate that a simple classifier based on white matter imaging data is able to predict the conversion to Alzheimer's disease with a high predictive power.

Breast tissue characterization with photon-counting spectral CT imaging: a postmortem breast study.

PURPOSE: To investigate the feasibility of breast tissue characterization in terms of water, lipid, and protein contents with a spectral computed tomographic (CT) system based on a cadmium zinc telluride (CZT) photon-counting detector by using postmortem breasts. MATERIALS AND METHODS: Nineteen pairs of postmortem breasts were imaged with a CZT-based photon-counting spectral CT system with beam energy of 100 kVp. The mean glandular dose was estimated to be in the range of 1.8-2.2 mGy. The images were corrected for pulse pile-up and other artifacts by using spectral distortion corrections. Dual-energy decomposition was then applied to characterize each breast into water, lipid, and protein contents. The precision of the three-compartment characterization was evaluated by comparing the composition of right and left breasts, where the standard error of the estimations was determined. The results of dual-energy decomposition were compared by using averaged root mean square to chemical analysis, which was used as the reference standard. RESULTS: The standard errors of the estimations of the right-left correlations obtained from spectral CT were 7.4%, 6.7%, and 3.2% for water, lipid, and protein contents, respectively. Compared with the reference standard, the average root mean square error in breast tissue composition was 2.8%. CONCLUSION: Spectral CT can be used to accurately quantify the water, lipid, and protein contents in breast tissue in a laboratory study by using postmortem specimens.