Dominik Spinczyk

Role of radiologists in CAD life-cycle

A modern CAD (computer-aided diagnosis) system development involves a multidisciplinary team whose members are experts in medical and technical fields. This study indicates the activities of medical experts at various stages of the CAD design, testing, and implementation. Those stages include a medical analysis of the diagnostic problem, data collection, image analysis, evaluation, and clinical verification. At each stage the physicians knowledge and experience are indispensable. The final implementation involves integration with the existing Picture Archiving and Communication System. The term CAD life-cycle describes an overall process of the design, testing, and implementation of a system that in its final form assists the radiologists in their daily clinical routine. Four CAD systems (applied to the bone age assessment, Multiple Sclerosis detection, lung nodule detection, and pneumothorax measurement) developed in our laboratory are given as examples of how consecutive stages are developed by the multidisciplinary team. Specific advantages of the CAD implementation that include the daily clinical routine as well as research and education activities are discussed.

Open architecture computer-aided diagnosis system

: In this study an approach to open architecture computer-aided diagnosis (CAD) is presented. The traditional goal of a CAD system, to assist the physicians in performing the diagnosis and treatment, has been extended. The platform also supports the system designer in developing a new CAD workflow by implementing general-purpose modules as well as problem-dependent procedures. A new CAD may require new procedures to be added, yet some of the already implemented functions can be employed. The CAD environment is subjected to the developmental process of three systems: the multiple sclerosis CAD, the lung nodule CAD and the pneumothorax CAD. Modules and procedures are briefly described and the CAD systems are evaluated. Results obtained during the CAD evaluation show prospective flexibility of the infrastructure. The trade-offs, well known to CAD designers, can easily be handled by the operators in a user-friendly manner by choosing various workflow paths.

Stereoscopic liver surface reconstruction

The paper presents a practical approach to measuring liver motion, both respiratory and laparoscopic, with a tool guided in the operating room. The presented method is based on standard operating room equipment, i.e. rigid laparoscopic cameras and a single incision laparoscopic surgery trocar. The triangulation algorithm is used and stereo correspondence points are marked manually by two independent experts. To calibrate the cameras two perpendicular chessboards, a pinhole camera model and a Tsai algorithm are used. The data set consists of twelve real liver surgery video sequences: ten open surgery and two laparoscopic, gathered from different patients. The setup equipment and methodology are presented. The proposed evaluation method based on both calibration points of the chessboard reconstruction and measurements made by the Polaris Vicra tracking system are used as a reference system. In the analysis stage we focused on two specific goals, measuring respiration and laparoscopic tool guided liver motions. We have presented separate examples for left and right liver lobes. It is possible to reconstruct liver motion using the SILS trocar. Our approach was made without additional position or movement sensors. Diffusion of cameras and laser for distance measurement seems to be less practical for in vivo laparoscopic data, but we do not exclude exploring such sensors in further research.

Continuous registration based on computed tomography for breathing motion compensation

Introduction Image guidance for intervention is applied for complex and difficult anatomical regions. Nowadays, it is typically used in neurosurgery, otolaryngology, orthopedics and dentistry. The application of the image-guided system for soft tissues is challenging due to various deformations caused by respiratory motion, tissue elasticity and peristalsis. Aim The main task for the presented approach is continuous registration of preoperative computed tomography (CT) and patient position in the operating room (OR) without touching the patient and compensation of breathing motion. This approach is being developed as a step to image-guided percutaneous liver RF tumor ablation. Material and methods Up to ten integrated radiological markers are placed on the patients skin before CT scans. Then the anatomical model based on CT images is calculated. Point-to-point registration based on the Horn algorithm during a few breathing cycles is performed using a videometric tracking system. The transformation which corresponds to the minimum fiducial registration error (FRE) is found during the registration and it is treated as the initial transformation for calculating local deformation field of breathing motion compensation based on the spline approach. Results For manual registration of the abdominal phantom, the mean values of target registration error (TRE), fiducial localization error (FLE) and FRE are all below 4 mm for the rigid transformation and are below 1 mm for the affine transformation. For the patients data they are all below 9 mm and 6 mm, respectively. For the automatic method, different marker configurations have been evaluated while dividing the respiratory cycle into inhale and exhale. Average median values for FRE, TRE rigid estimation and TRE based on spline deformation were 15.56 mm, 0.82 mm and 7.21 mm respectively. Conclusions In this application two registration methods of abdominal preoperative CT anatomical model and physical patient position in OR were presented and compared. The presented approach is being developed as a step to image-guided percutaneous liver radiofrequency ablation tumor ablation. Implementation of the automated registration method to clinical practice is easier because of shortening of preparation time in OR, no necessity of touching the patient, and no dependency on the physicians experience.

Preparing the anatomical model for ablation of unresectable liver tumor

Introduction Nowadays the best treatment of the primary and secondary hepatic tumor is surgical resection, but only 5–15% of all patient with hepatocellular carcinoma and 20–25% of all patients with liver metastases are indicated for resection. In these cases some kind of ablation and other technique could be used. Aim To present the methodology of preparing the anatomical model for ablation of unresectable liver tumor. Material and methods The presented method is based on abdomen computed tomography (CT) dynamic examination. Three methods of segmentation are used: rolling vector for liver volume, modified Frangi filter for liver vessels, and fuzzy expert system with initial region-of-interest anisotropic filtration for liver metastases. Segmentation results are the input data for creating 3D anatomical models in the form of B-spline curves and surfaces performing the surface global interpolation algorithm. A graphical user interface for presentation and evaluation of models, presented in color against DICOM images in grayscale, is designed and implemented. Results The proposed approach was tested on 20 abdominal CT obtained from the Department of Clinical Radiology of Silesian Medical University. The lack of a “gold standard” provides for the correction of the results. Conclusions Preparation of the anatomical model is one of the important early stages of the use of image-based navigation systems. This process could not take place in a fully automatic manner and verification of the results obtained is performed by the radiologist. Using the above anatomical model in surgical workflow is presented.

In-vitro evaluation of stereoscopic liver surface reconstruction

Introduction Tracking abdominal motion of organs is an important factor in image-guided navigation systems. The paper presents the evaluation methodology of a practical approach to measure liver motion, both respiratory and laparoscopic, with a tool guided in the operating room. Aim Evaluation of the methodology of a practical approach to measure liver motion, both respiratory and laparoscopic, with a tool guided in the operating room. Material and methods The presented evaluation method is based on standard operating room equipment, i.e. laparoscopic cameras. We decided to use two rigid cameras to gain stereo in order to reconstruct characteristic points by triangulation. Our research aim was to survey the impact of three parameters on reconstruction accuracy: the number of calibration points, the imprecision of camera assembly, and the difference in resolution of images. Results Three calibration chessboard configurations were tested. The reconstructed landmark positions and residual mean square errors were presented in three phantom poses: the reference position, translated position and rotated position. Conclusions The presented approach is a development of the previous work. Our research proved the importance of a rigid stereo camera system and the use of high definition image resolution for both stages, namely calibration and reconstruction.

Methods for abdominal respiratory motion tracking

Abstract Non-invasive surface registration methods have been developed to register and track breathing motions in a patient’s abdomen and thorax. We evaluated several different registration methods, including marker tracking using a stereo camera, chessboard image projection, and abdominal point clouds. Our point cloud approach was based on a time-of-flight (ToF) sensor that tracked the abdominal surface. We tested different respiratory phases using additional markers as landmarks for the extension of the non-rigid Iterative Closest Point (ICP) algorithm to improve the matching of irregular meshes. Four variants for retrieving the correspondence data were implemented and compared. Our evaluation involved 9 healthy individuals (3 females and 6 males) with point clouds captured in opposite breathing phases (i.e., inhalation and exhalation). We measured three factors: surface distance, correspondence distance, and marker error. To evaluate different methods for computing the correspondence measurements, we defined the number of correspondences for every target point and the average correspondence assignment error of the points nearest the markers.

Multimedia System for Accessible Distant Education

Paper describes a computer system enabling interactive online presentation of multimedia Daisy books over the Internet. The system cooperates with the Internet multimedia library computer management system. The main goal of both projects and their execution, is easy and effective access to information for visually impaired people. We focus on new feature of our DaisyReader which allows interactive voice reading of math formulas.

Automatic Generation of 3D Lung Model

The paper presents a method generating a 3D lungs model. The model is represented by a B-spline surface, generated by the global surface interpolation algorithm. The model to be derived is based on a vector of automatically obtained points marked on the contour of the lungs. Active contour method is used to make the lung segmentation more robust.

Tutoring math platform accessible for visually impaired people

BACKGROUND There are many problems with teaching and assessing impaired students in higher education, especially in technical science, where the knowledge is represented mostly by structural information like: math formulae, charts, graphs, etc. Developing e-learning platform for distance education solves this problem only partially due to the lack of accessibility for the blind. METHOD The proposed method is based on the decomposition of the typical mathematical exercise into a sequence of elementary sub-exercises. This allows for interactive resolving of math exercises and assessment of the correctness of exercise solutions at every stage. The presented methods were prepared and evaluated by visually impaired people and students. RESULTS The article presents the accessible interactive tutoring platform for math teaching and assessment, and experience in exploring it. The results of conducted research confirm good understanding of math formulae described according to elaborated rules. Regardless of the level of complexity of the math formulae the level of math formulae understanding is higher for alternative structural description. CONCLUSIONS The proposed solution enables alternative descriptions of math formulae. Based on the research results, the tool for computer-aided interactive learning of mathematics adapted to the needs of the blind has been designed, implemented and deployed as a platform for on-site and online and distance learning. The designed solution can be very helpful in overcoming many barriers that occur while teaching impaired students.