Catheter Path Research Articles

Neural network reconstruction of the left atrium using sparse catheter paths.

Catheter-based radiofrequency ablation for pulmonary vein isolation has become the first line of treatment for atrial fibrillation in recent years. This requires a rather accurate map of the left atrial sub-endocardial surface including the ostia of the pulmonary veins, which requires dense sampling of the surface and currently takes more than 10min. The focus of this work is to provide left atrial visualization early in the procedure to ease procedure complexity and enable further workflows, such as using catheters that have difficulty sampling the surface. We propose a dense encoder-decoder network with a novel regularization term to reconstruct the shape of the left atrium from partial data which is derived from simple catheter maneuvers. To train the network, we acquire a large dataset of 3D atria shapes and generate corresponding catheter trajectories, from which traversed point clouds are obtained. Once trained, we show that the suggested network can sufficiently approximate the atrium shape based on a given trajectory. We compare several network solutions for the 3D atrium reconstruction. We demonstrate that the solution proposed produces realistic visualization using partial acquisition within a 3-min time interval using human clinical cases.

Morphology-based non-rigid registration of coronary computed tomography and intravascular images through virtual catheter path optimization.

Coronary computed tomography angiography (CCTA) provides 3D information on obstructive coronary artery disease, but cannot fully visualize high-resolution features within the vessel wall. Intravascular imaging, in contrast, can spatially resolve atherosclerotic in cross sectional slices, but is limited in capturing 3D relationships between each slice. Co-registering CCTA and intravascular images enables a variety of clinical research applications but is time consuming and user-dependent. This is due to intravascular images suffering from non-rigid distortions arising from irregularities in the imaging catheter path. To address these issues, we present a morphology-based framework for the rigid and non-rigid matching of intravascular images to CCTA images. To do this, we find the optimal virtual catheter path that samples the coronary artery in CCTA image space to recapitulate the coronary artery morphology observed in the intravascular image. We validate our framework on a multi-center cohort of 40 patients using bifurcation landmarks as ground truth for longitudinal and rotational registration. Our registration approach significantly outperforms other approaches for bifurcation alignment. By providing a differentiable framework for multi-modal vascular co-registration, our framework reduces the manual effort required to conduct large-scale multi-modal clinical studies and enables the development of machine learning-based co-registration approaches.

A cross-sectional study on non-infectious dysfunction of hemodialysis cuffed catheter.

Dialysis cuffed catheter dysfunction results in inadequate dialysis, increased sepsis risk,and a shortenedcatheter life. It may be possible to prolong catheter function by identifying the causes of cuffed catheter dysfunction. This study was a cross-sectional descriptive study conducted in 2021-2022 on hemodialysis patients with jugular cuff catheters. The catheterizations were performed using the Seldinger technique and were confirmed by fluoroscopy. A 12-month follow-up was conducted with respect to the performance of the cuffed catheter. A total of 123 patients underwent hemodialysis over 2 years via a cuffed catheter. Catheters were most commonly inserted into the right internal jugular vein, with lengths of 19 cm (tip to cuff). The rate of dysfunction of cuffed catheters was 27.6%. Catheter-related thrombosis was the most common cause in 10 cases (29.4%), followed by catheter tip fibrin sheath in 8 cases (23.5%) and catheter tip malposition in 8 cases (23.5%). Furthermore, 18 patients (52.94%) of cuffed catheter dysfunction occurred within 3 months of catheter placement, based on our study. The dysfunction of cuffed catheters on the left side 23 (67.64%) is more prevalent than the right side 11 (32.35%) (P=0.043); the malposition of catheter tips is more prevalent on the left side (P=0.023). Most commonly, cuffed catheter dysfunction is caused by thrombosis, fibrin sheath formation, and catheter tip malposition. Cuffed catheter failure can be reduced by carefully monitoring the catheter's path and tip position, searching for fibrin sheaths when investigating cuffed catheter failure, and preventing thrombotic events.

Extending bioelectric navigation for displacement and direction detection

PurposeBioelectric navigation is a navigation modality for minimally invasive endovascular procedures promising non-fluoroscopic navigation. However, the method offers only limited navigation accuracy between anatomical features and expects the tracked catheter to move only in one direction at all times. We propose to extend bioelectric navigation with additional sensing capabilities, allowing for the estimation of the distance traveled by the catheter, thereby improving accuracy between feature locations and allowing to track also under alternating forward- and backward motion.MethodsWe perform experiments in finite element method (FEM) simulations and in a 3D printed phantom. A solution for estimating the traveled distance using a stationary electrode is proposed, together with an approach on how to evaluate the signals obtained with this additional electrode. We investigate the effects of surrounding tissue conductance on this approach. Finally, the approach is refined in order to mitigate the effects of parallel conductance on the navigation accuracy.ResultsThe approach allows to estimate the catheter movement direction and the distance traveled. Simulations show absolute errors below 0.89 mm for non-conducting surrounding tissue, but errors up to 60.27 mm when the tissue is electrically conductive. This effect can be mitigated by a more sophisticated modeling (errors up to 33.96 mm). In experiments in a 3D printed phantom, the mean absolute error over 6 catheter paths is 6.3 mm, with standard deviations smaller than or equal to 1.1 mm.ConclusionsExtending the setup of bioelectric navigation with an additional stationary electrode allows to estimate the distance traveled by the catheter, as well as the movement direction. The effects of parallel conductive tissue could be partially mitigated in simulations, but further research is needed to investigate these effects in real biological tissue, and to bring the introduced errors down to a clinically acceptable level.

Physical Simulation of Transcatheter Edge-to-Edge Repair Using Image-Derived 3D Printed Heart Models

BackgroundTranscatheter edge-to-edge valve repair (TEER) is a complex procedure requiring delivery and alignment of the device to the target valve, which can be challenging in atypical or surgically palliated anatomy. We demonstrate application of virtual and physical simulation to plan optimal TEER access and catheter path in normal and congenitally abnormal cardiac anatomy. MethodsThree heart models were created from 3-dimensional (3D) images and 3D printed, including 2 with congenital heart disease. TEER catheter course was simulated both virtually and physically using a commercial TEER system. ResultsWe demonstrate application of modeling in 3 patients, including 2 with congenital heart disease and a Fontan circulation. Access site and pathway to device delivery were simulated by members of a multidisciplinary valve team. Virtual and physical simulations were compared. ConclusionsVirtual and physical simulation of TEER using 3D printed heart models is feasible and may be beneficial for planning and simulation, particularly in patients with complex anatomy. Future work is required to demonstrate application in the clinical setting.

Paths of thoracic epidural catheters in children undergoing the Nuss procedure for pectus excavatum repair

PurposeTo investigate the paths of thoracic epidural catheters in children, this retrospective study was performed.MethodsWe investigated 73 children aged 4 to 12 (mean ± SD 7.8 ± 2.3) years, who underwent the Nuss procedure for pectus excavatum repair under combined general and epidural anesthesia over a 5-year period at Tokyo Metropolitan Police Hospital. Following induction of general anesthesia, we inserted a radiopaque epidural catheter via the T5/6 or T6/7 interspace and advanced for 5 cm cephalad in the thoracic epidural space. We evaluated the paths of the epidural catheters on plain chest radiographs after surgery.ResultsThe median level for the catheter tip location was T3 (range C6–T7), while the median number of vertebrae crossed by the catheter tips was 2.5. In most children, the catheters advanced straight for the first 2–3 cm (1–1.5 vertebrae) in the thoracic epidural space. However, they continued to advance straight in only 25 children, while they exhibited curved or coiled paths in the remaining 48. The catheter tips were located at higher levels in children with straight epidural catheter paths [median (range) T2 (C6–T4)] than in those with curved or coiled paths after the initial 2–3 cm [median (range) T4 (T2–T7)] (p < 0.0001).ConclusionsOur findings indicate that the course of epidural catheters in children is unpredictable after the first 2–3 cm in the thoracic epidural space. Clinicians should be aware of such findings, although further studies are required for confirmation.

Performance of an enhanced afterloader with electromagnetic tracking capabilities for channel reconstruction and error detection.

To assess catheter reconstruction and error detection performance of an afterloader (Elekta Brachytherapy, Veenendaal, The Netherlands) equipped with electromagnetic (EM) tracking capabilities. The Flexitron research unit used was equipped with a special check cable integrating an EM sensor (NDI Aurora V3) that enables tracking and reconstruction capability. The reconstructions of a 24-cm long catheter were performed using two methods: continuous fixed-speed check cable backward stepping (at 1, 2.5, 5, 10, 25 and 50cm/s) and stepping through each dwell position every 1mm. The ability of the system to differentiate between two closely located (parallel) catheters was investigated by connecting catheters to the afterloader and moving it from its axis with an increment of 1mm. A robotic arm (Meca500, Mecademic, Montreal) with an accuracy of 0.01mm was used to move the catheter between each reconstruction. Reconstructions were obtained with a locally weighted scatterplot smoothing algorithm. To quantify the reconstruction accuracy, distances between two catheters were computed along the reconstruction track with a 5mm step. The reconstructions of curve catheter paths were assessed through parallel and perpendicular phantom configuration to the EM field generator. Indexer length and lateral errors were simulated and a ROC analysis was made. Using a 50cm/s check cable speed does not allow for accurate reconstructions. A slower check cable speed results in better reconstruction performance and smaller standard deviations. At 1cm/s, a catheter can be shifted laterally down to 1mm and all paths can be uniquely identified. The optimum operating distance from the field generator (50 to 300mm) resulted in a lower absolute mean deviation from the expected value (0.2±0.1mm) versus being positioned on the edge of the electromagnetic sensitive detection volume (0.6±0.3 mm). The reconstructions of curved catheters with a check cable speed under 5cm/s gave a 0.8mm±0.3mm error, or better. All indexer and lateral shifts of 1mm were detected with a check cable speed of 2.5cm/s or lower. The EM-equipped Flexitron afterloader is able to track and reconstruct catheters with high accuracy. A speed under 5cm/s is recommended for straight and curved catheter reconstructions. It allows catheter identification down to 1mm inter-catheter distance shift. The check cable can also be used to detect common shift errors.

PP-0146 Quality assurance of curved catheter paths in interstitial brachytherapy using a constructed phantom

PP-0146 Quality assurance of curved catheter paths in interstitial brachytherapy using a constructed phantom

Predictive Value of Preprocedural Computed Tomography Angiography for the Technical Success of Transarterial Embolization of Type II Endoleaks Arising from the Lumbar Arteries

PurposeTo evaluate the ability of preprocedural computed tomography angiography (CTA) to predict the technical success of embolization of type II endoleak arising from a lumbar artery after endovascular aortic repair (EVAR). Materials and MethodsAll patients at a single academic institution who underwent angiography with possible embolization for a post-EVAR lumbar-supplied type II endoleak from 2009 to 2018 were retrospectively reviewed. Patients who did not undergo CTA before the procedure were excluded. CTAs were reviewed for the ability to trace the entire course of a feeding vessel from the internal iliac artery (IIA) to the lumbar artery at the site of the endoleak. Procedural imaging was reviewed for technical success, defined as the catheterization and embolization of the aneurysm sac through a lumbar artery. ResultsFifty-seven angiograms with a type II endoleak and suspected feeding lumbar artery were identified. On CTA acquired before the procedure, the arterial path supplying this lumbar artery could be traced from the IIA to the aneurysm sac in 18 (32%) patients. Embolization was technically successful in 16 of these 18 (89%) procedures compared with 10 of 39 (26%) procedures in which the supplying artery could not be traced using CTA (P < .001). ConclusionsA potential catheter path from the IIA through the iliolumbar and lumbar arteries to the aneurysm sac can be traced on preprocedural CTA in the minority of lumbar-supplied type II endoleaks. The ability to trace these inflow vessels may predict technical success during embolization. The low rate of technical success when the feeding vessel could not be traced using CTA suggests that these patients should be considered for percutaneous or transcaval sac puncture.

Evaluation Of MR Only Trans-Perineal Interstitial Gynecological HDR Brachytherapy Workflow Using MR-Line Marker And MR Template

There is a growing interest in using MR-only trans-perineal gynecological interstitial brachytherapy because it offers excellent soft-tissue contrast due to MR imaging while reducing the resources required for planning and uncertainty due to registration with CT. The purpose of this work is to evaluate the variation in MR-only workflow in comparison to CT guided approach in gynecological trans-perineal interstitial high dose rate (HDR) brachytherapy. An in-house MR-line marker was designed and created to provide positive contrast on T1W MR images for delineating 6F interstitial catheters (Elekta), replacing the need for CT. A marker plate filled with contrast was affixed to the trans-perineal template, providing a clear reference plane for planning on T1W MR images. Ten patients diagnosed with locally advanced cervical cancer treated with HDR brachytherapy were retrospectively evaluated. An MR-only workflow was developed that used the positive contrast from the MR-markers on T1W images in conjunction with negative contrast on T2W images, to robustly and accurately delineate the interstitial catheters. Inter-observer variability in delineated catheter paths and time required to delineate the catheters were evaluated for 3 therapists and 2 medical physicists. A dosimetric comparison of the plans in the MR-only workflow was made with those in CT based workflow. The contrast in the MR-line marker was stable over time. MR-line markers were visible on planning T1-3D MR images but the complementary information from co-registered T2-3D images were needed at some anatomical locations where the background signal was comparable to that of the markers. MR-template helped to make quality assurance of reconstructed catheter lengths and hence to locate the first dwell point reliably. More than about 97% of catheter reconstruction variations were within 2mm. There were no statistical differences in gross tumor volume (GTV) D98 and High-risk clinical target volume (HR-CTV) D90 and the organs at risk (Bladder, sigmoid, rectum and bowel) D2cc between MR-only and hybrid CT/MR workflow. The average catheter reconstruction time was 51 ± 10 minutes across all ten patients for all observers. The results of this study show that the MR-only workflow is feasible. The use of MR markers enabled accurate and reproducible delineation of the catheters. Furthermore, it was also demonstrated that an MR-only workflow is dosimetrically equivalent to a CT based approach.

Pilot Study of Use of Electromagnetic Tracking Technology to Reconstruct Catheter Paths in Breast Brachytherapy

Pilot Study of Use of Electromagnetic Tracking Technology to Reconstruct Catheter Paths in Breast Brachytherapy

91: Use of Electromagnetic Tracking Technology to Reconstruct Catheter Paths in Breast Brachytherapy-A Pilot Study

91: Use of Electromagnetic Tracking Technology to Reconstruct Catheter Paths in Breast Brachytherapy-A Pilot Study

Electromagnetic (EM) catheter path tracking in ultrasound-guided brachytherapy of the breast.

To evaluate a novel navigation system for breast brachytherapy, based on ultrasound (US)-guided catheter needle implantations followed by electromagnetic (EM) tracking of catheter paths. Breast phantoms were produced, containing US-visible tumors. Ultrasound was used to localize the tumor pose and volume within the phantom, followed by planning an optimal catheter pattern through the tumor using navigation software. An electromagnetic (EM)-tracked catheter needle was used to insert the catheters in the desired pattern. The inserted catheters were visualized on a post-implant CT, serving as ground truth. Electromagnetic (EM) tracking and reconstruction of the inserted catheter paths were performed by pulling a flexible EM guidewire through each catheter, performed in two clinical brachytherapy suites. The accuracy of EM catheter tracking was evaluated by calculating the Hausdorff distance between the EM-tracked and CT-based catheter paths. The accuracy and clinical feasibility of EM catheter tracking were also evaluated in three breast cancer patients, performed in a separate experiment room. A total of 71 catheter needles were implanted into 12 phantoms using US guidance and EM navigation, in an average ± SD time of 8.1 ± 2.9min. The accuracy of EM catheter tracking was dependent on the brachytherapy suite: 2.0 ± 1.2mm in suite 1 and 0.6 ± 0.2mm in suite 2. EM catheter tracking was successfully performed in three breast brachytherapy patients. Catheter tracking typically took less than 5min and had an average accuracy of 1.7 ± 0.3mm. Our preliminary results show a potential role for US guidance and EM needle navigation for implantation of catheters for breast brachytherapy. EM catheter tracking can accurately assess the implant geometry in breast brachytherapy patients. This methodology has the potential to evaluate catheter positions directly after the implantation and during the several fractions of the treatment.

Evaluation of an MR-only interstitial gynecologic brachytherapy workflow using MR-line marker for catheter reconstruction

PurposeMagnetic resonance imaging (MRI) offers excellent soft-tissue contrast enabling the contouring of targets and organs at risk (OARs) during gynecological interstitial brachytherapy procedure. Despite its benefit, one of the main challenges toward MRI-only workflows is that the implanted catheters are not reliably visualized on MR images. This study aims to evaluate the feasibility of MR-only workflow using an in-house MR line marker during interstitial gynecological high-dose-rate (HDR) brachytherapy. Methods and MaterialsTen patients diagnosed with locally advanced cervical cancer treated with HDR brachytherapy were included in this study. The hybrid CT/MR-treated plan was used as the study reference plan. Five users manually reconstructed the catheter's path on MR images (3D T1- and T2-weighted). Subsequently, the dwell positions from the users’ plans were superimposed on the reference plans to evaluate the dosimetric impact of the using MR-only for catheter reconstruction in comparison with hybrid CT/MR approach. Variability of dwell positions between users and reconstruction time was also evaluated. ResultsMore than 96.90% of catheter reconstruction variations were < 2 mm. No statistical differences were reported between MR-only and hybrid CT/MR in gross tumor volume D98 and high-risk clinical target volume D90, respectively. For the OARs (bladder, sigmoid, rectum, and bowel), no significant changes were observed in any dose metrics between MR-only and hybrid CT/MR. The average reconstruction time was 51 ± 10 minutes across all ten patients. ConclusionThe feasibility of MR-only workflow using MR line marker during interstitial gynecological HDR brachytherapy has been validated in this study. The results show that the MR-only workflow is equivalent to the conventional hybrid CT/MR approach in terms of gross tumor volume and high-risk clinical target volume coverage and respecting of OARs dose limits.

Quantification of the temperature gradient through a catheter in continuous infusion thermodilution for coronary flow measurements

Objective: Quantifying the absolute coronary blood flow can be done using continuous infusion thermodilution requiring a dedicated infusion catheter. Up to now, there has been little insight into the effect of small variabilities in the physical parameters on the temperature gradient along this catheter. The key goal of this study is to develop and validate a computer model that predicts the temperature of the infusion fluid at the infusion site of the infusion catheter. A secondary goal is to gain insight into the influence of physical variations for the individual patient on the calculated blood flow rate. Approach: A numerical model of the temperature in the catheter was built using the convection–diffusion equation and validated using an in vitro setup. A sensitivity analysis was performed to investigate the influence of the catheter path inside the body and the temperature of the infusion fluid at different infusion rates. These results were compared to in vivo measurements of 94 patients. Finally, the variation in the computed blood flow rate is estimated considering an average patient, using small variations in the physical parameters. Main results: The computed temperature corresponded well with the in vitro measurements, since a maximal difference of 1.5% was observed. The length of the catheter path inside the body had the most influence on the temperature of the infusion fluid at the infusion site. Moreover, temperatures from the numerical model were similar to the results from in vivo measurements. By varying the length of the catheters with 0.04 m, the largest deviation in the calculated blood flow was 33.3 ml/min. Significance: Insight is gained into the influence of physical variations on the temperature of the infusion fluid at the infusion site of the catheter using thermodilution. The developed numerical model can possibly be used to reduce time in estimating the blood flow rate.

3 Electromagnetic Reconstruction of Catheter Paths in Breast Brachytherapy

3 Electromagnetic Reconstruction of Catheter Paths in Breast Brachytherapy

Use of Electromagnetic Reconstruction of Catheter Paths in Breast Brachytherapy

Use of Electromagnetic Reconstruction of Catheter Paths in Breast Brachytherapy

04:12 PM Abstract No. 31 Predictive value of pre-procedural computed tomography angiogram on technical success of transarterial embolization of type II endoleaks arising from lumbar arteries

To evaluate the ability of pre-procedural CTA to predict the technical success of embolization of post-EVAR type II endoleaks arising from lumbar arteries. All patients at a single academic institution with post-EVAR type II endoleak from 2008-2018 were retrospectively reviewed. Patients without CTA were excluded. CTAs were reviewed for the ability to trace the entire course of vessels feeding the endoleak. Successful tracing was defined as identification of a feeding vessel from the internal iliac artery to the lumbar artery at the site of endoleak. Procedural imaging was reviewed for technical success, defined as catheterization of the lumbar artery at the site of endoleak. Sixty-eight patients with a type II endoleak underwent 75 transarterial interventions during the study period. Of these interventions, CTA prior to 57 angiograms (76%) showed a type II endoleak with a suspected feeding lumbar artery based on endoleak location along the posterior wall of the aorta. The supplying artery could be traced on prior CTA in 18 (32%) procedures, and embolization was technically successful in 16/18 (89%). In the remaining 39 (68%) procedures where the supplying artery could not be traced on prior CTA, the technical success rate was 10/39 (26%). The 31 endoleaks that were not treated via the iliolumbar artery branches were managed with embolization of the IMA origin through the Arc of Riolan (n=5), percutaneous aneurysm sac puncture (n=17), transcaval sac puncture (n=2), additional endograft placement (n=1), or active surveillance (n=6). A potential catheter path from the internal iliac artery through the iliolumbar and lumbar arteries to the aneurysm sac can be traced on CTA in the minority of lumbar-supplied type II endoleaks. The ability to trace these inflow vessels on preprocedural CTA is a reliable predictor of technical success during embolization. Low rates of technical success were identified when the feeding vessel could not be traced on CTA, suggesting these patients should be considered for a different approach such as percutaneous or transcaval aneurysm sac puncture.

Optimized penile surface mold brachytherapy using latest stereolithography techniques: A single-institution experience

PurposeTo describe a technique of penile surface mold high-dose-rate (HDR) brachytherapy and early outcomes. Methods and MaterialsFive patients diagnosed with a T1aN0 squamous cell carcinoma of the penis were treated using a penile surface mold HDR brachytherapy technique. A negative impression of the penis was obtained using dental alginate. CT images were acquired of the penile impression; subsequently, a virtual model of the patient's penis was generated. The positive model was imported into a computer-assisted design program where catheter paths were planned such that an optimized offset of 5 mm from the penile surface was achieved. The virtual model was converted into a custom applicator. A total dose of 40 Gy was delivered in 10 fractions. Patients were followed at 1, 3, 6, and 12 months after treatment and then every 6 months thereafter. Toxicities were reported using Common Terminology Criteria for Adverse Events v4.0. ResultsAll patients tolerated treatment well. Acute Grade 2 skin reactions were observed within the first month after treatment. Median followup was 35 months. Late Grade 1 skin toxicities were observed. One patient experienced a urethral stricture requiring dilatation. Two patients developed local recurrence. ConclusionThis technique allows the delivery of penile HDR brachytherapy as an outpatient procedure with minimal discomfort to the patient during each application and is a repeatable and accurate setup. This technique warrants validation in larger series with longer followup.

Atlanto-axial rotatory fixation complicating ventriculo-peritoneal shunt surgery: a case report and literature review

Atlanto-axial rotatory fixation (AARF) is a rare complication of ventriculo-peritoneal shunt (VPS) surgery. The authors present a unique case of AARF developing early after VP shunting, with persistent torticollis, a "cock-robin" head position, and a thick fibrous band along the catheter path. Due to refractoriness to conservative treatments, AARF, which can be an early-onset complication of VPS surgery, was resolved by removing the distal catheter along with the fibrous band encasing it. Surgical removal of the fibrous band might be enough to solve such complication with no need of further surgical fusion procedures.