Geometric inaccuracy and co-registration errors for CT, DynaCT and MRI images used in robotic stereotactic radiosurgery treatment planning

Image Fusion of High-Resolution DynaCT and T2-Weighted MRI for Image-Guided Programming of dDBS

Objectives: This study aimed to develop a semi-automated registration method for aligning preoperative non-contrast T2-weighted MRI with postoperative high-resolution cone-beam CT (DynaCT) in patients undergoing directional deep brain stimulation (dDBS) surgery targeting the subthalamic nucleus (STN). The aim was to facilitate image-guided programming of DBS devices and postoperative verification of the alignment of segmented contacts. Materials and Methods: A dataset of ten patients undergoing bilateral dDBS implantation was retrospectively collected, including DynaCT (acquired postoperatively) and non-contrast T2-weighted MRI (obtained preoperatively). A semi-automated registration method was used, employing manual initialization due to dissimilar anatomical information between DynaCT and T2-weighted MRI. Image visualization, initial alignment using a centered transformation initializer, and single-resolution image registration involving the Simple Insight Toolkit (SimpleITK) library were performed. Manual landmark-based alignment based on anatomical landmarks and evaluation metrics such as Target Registration Error (TRE) assessed alignment accuracy. Results: The registration method successfully aligned all images. Quantitative evaluation revealed an average of the mean TRE of 1.48 mm across all subjects, indicating satisfactory alignment quality. Multiplanar reformations (MPRs) based on electrode-oriented normal vectors visualized segmented contacts for accurate electrode placement. Conclusions: The developed method demonstrated successful registration between preoperative non-contrast T2-weighted MRI and postoperative DynaCT, despite dissimilar anatomical information. This approach facilitates accurate alignment crucial for DBS programming and postoperative verification, potentially reducing the programming time of the DBS. The study underscores the importance of image quality, manual initialization and semi-automated registration methods for successful multimodal image registration in dDBS procedures targeting the STN.

Application of DynaCT biliary soft tissue reconstruction technology in diagnosis and treatment of hepatolithiasis

BACKGROUND

Hepatobiliary stone disease involves an intrahepatic bile duct stone that occurs above the confluence of the right and left hepatic ducts. One-step percutaneous transhepatic cholangioscopic lithotripsy (PTCSL) using the percutaneous transhepatic one-step biliary fistulation (PTOBF) technique enables the clearing of intrahepatic stones and the resolution of strictures. However, hepatolithiasis with associated strictures still has high residual and recurrence rates after one-step PTCSL. DynaCT can achieve synchronized acquisition with a flat-panel detector during C-arm rotation. The technical approach and application value of DynaCT biliary soft tissue reconstruction technology for the diagnosis and treatment of hepatolithiasis with bile duct stenosis were evaluated in this study.

AIM

To explore the value of DynaCT biliary soft tissue reconstruction technology for the diagnosis and treatment of hepatolithiasis with bile duct stenosis, and to assess the feasibility and effectiveness of the PTOBF technique guided by DynaCT biliary soft tissue reconstruction technology.

METHODS

The clinical data of 140 patients with complex biliary stenosis disease combined with bile duct stenosis who received PTOBF and were admitted to the First Affiliated Hospital of Guangzhou Medical University from January 2020 to December 2024 were collected. The patients were divided into two groups: DynaCT-PTOBF group (70 patients) and conventional PTOBF group (70 patients). These groups were compared in terms of the preoperative bile duct stenosis, location of the liver segment where the stone was located, intraoperative operative time, immediate stone retrieval rate, successful stenosis dilatation rate, postoperative complication rate, postoperative reoperation rate, stone recurrence rate, and stenosis recurrence rate.

RESULTS

DynaCT biliary soft tissue reconstruction technology was successfully performed in 70 patients. The DynaCT-PTOBF group had a higher detection rate of target bile ducts where bile duct stones and biliary strictures were located than the PTOBF group. Compared with the PTOBF group, the DynaCT-PTOBF group was characterized by a significantly greater immediate stone removal rate (68.6% vs 50.0%, P = 0.025), greater immediate stenosis dilatation success rate (72.9% vs 55.7%, P = 0.034), greater final stenosis release rate (91.4% vs 75.7%, P = 0.012), shorter duration of intraoperative hemorrhage (3.14 ± 2.00 vs 26.5 ± 52.1, P = 0.039), and lower incidence of distant cholangitis (2.9% vs 11.4%, P = 0.49). There were no significant differences between the two groups in terms of the final stone removal rate, reoperation rate, or long-term complication incidence rate.

CONCLUSION

DynaCT biliary soft tissue reconstruction technology guiding the PTOBF technique in patients with hepatolithiasis with bile duct stenosis is feasible and accurate. It may be beneficial for optimizing the preoperative evaluation of the PTOBF technique.

Artificial intelligence in radiotherapy: Current applications and future trends

Radiation therapy has dramatically changed with the advent of computed tomography and intensity modulation. This added complexity to the workflow but allowed for more precise and reproducible treatment. As a result, these advances required the accurate delineation of many more volumes, raising questions about how to delineate them, in a uniform manner across centers. Then, as computing power improved, reverse planning became possible and three-dimensional dose distributions could be generated. Artificial intelligence offers the opportunity to make such workflow more efficient while increasing practice homogeneity. Many artificial intelligence-based tools are being implemented in routine practice to increase efficiency, reduce workload and improve homogeneity of treatments. Data retrieved from this workflow could be combined with clinical data and omic data to develop predictive tools to support clinical decision-making process. Such predictive tools are at the stage of proof-of-concept and need to be explainatory, prospectively validated, and based on large and multicenter cohorts. Nevertheless, they could bridge the gap to personalized radiation oncology, by personalizing oncologic strategies, dose prescriptions to tumor volumes and dose constraints to organs at risk.

Co-Registration of pre- and post-Operative images after cochlear Implantation: A proposed technique to Improve cochlear visualization and localization of cochlear electrodes

BACKGROUND AND PURPOSE

After cochlear implantation, metallic artifact can obscure nearby structures on CT images, which is problematic in patients with facial nerve stimulation (FNS). This study evaluated the usefulness of co-registered pre- and post-operative examinations to evaluate the cochlear implant and adjacent structures.

MATERIALS AND METHODS

A retrospective review was completed of consecutive patients that underwent CT imaging of the temporal bone before and after placement of a cochlear implant. Two blinded neuroradiologists independently reviewed all available examinations. All examinations were assessed for the presence or absence of dehiscence of the osseous ridge between the cochlea and facial nerve canal (FNC). Pre-operative and fused pre- and post-operative examinations were compared in their ability to visualize the osseous ridge using a 5-point Likert scale (ranging from 1 = unfused images were substantially superior to 5 = fused images were substantially superior). The electrode closest to the FNC were noted.

RESULTS

Of 34 included patients, 13 (38.2%) were female and 21 (61.8%) were male; average age was 72.2. Seven patients (20.6%) had frank dehiscence between the cochlea and FNC. Fused images were superior to the post-operative study alone for assessing the integrity of the osseous partition between the cochlea and FNC and for reducing artifact from the electrode array (average Likert scores for both reviewers were 4.4 and 4.7). There was good agreement between reviewers in noting electrode closest to the FNC (concordance correlation coefficient=0.82).

CONCLUSIONS

Following cochlear implantation, co-registered pre- and post-operative CT images are superior to conventional images in assessing the anatomic relationship between the cochlea and FNC.