Pulmonologist evaluation on new CT visualization for guidance to lung lesions during bronchoscopy.

OBJECTIVE: Endoluminal visualization in virtual and video bronchoscopy lacks information about the surrounding structures, and the traditional 2 D axial, coronal and sagittal CT views can be difficult to interpret. To address this challenge, we previously introduced a novel visualization technique, Anchored to Centerline Curved Surface, for navigated bronchoscopy. The current study compares the ACCuSurf to the standard ACS CT views as planning and guiding tools in a phantom study. MATERIAL AND METHODS: Bronchoscope operators navigated in physical phantom guided by virtual realistic image data constructed by fusion of CT dataset of phantom and anonymized patient CT data. We marked four different target positions within the virtual image data and gave 12 pulmonologists the task to navigate, with either ACCuSurf or ACS as guidance, to the corresponding targets in the physical phantom. RESULTS: Using ACCuSurf reduced the planning time and increased the grade of successful navigation significantly compared to ACS. CONCLUSION: The phantom setup with virtual patient image data proved realistic according to the pulmonologists. ACCuSurf proved superior to ACS regarding planning time and navigation success grading. Improvements on visualisation or display techniques may consequently improve both planning and navigated bronchoscopy and thus contribute to more precise lung diagnostics.

A new visualization method for navigated bronchoscopy.

OBJECTIVE: In flexible endoscopy techniques, such as bronchoscopy, there is often a challenge visualizing the path from start to target based on preoperative data and accessing these during the procedure. An example of this is visualizing only the inside of central airways in bronchoscopy. Virtual bronchoscopy (VB) does not meet the pulmonologist's need to detect, define and sample the frequent targets outside the bronchial wall. Our aim was to develop and study a new visualization technique for navigated bronchoscopy. MATERIAL AND METHODS: We extracted the shortest possible path from the top of the trachea to the target along the airway centerline and a corresponding auxiliary route in the opposite lung. A surface structure between the centerlines was developed and displayed. The new technique was tested on non-selective CT data from eight patients using artificial lung targets. RESULTS: The new display technique anchored to centerline curved surface (ACCuSurf) made it easy to detect and interpret anatomical features, targets and neighboring anatomy outside the airways, in all eight patients. CONCLUSIONS: ACCuSurf can simplify planning and performing navigated bronchoscopy, meets the challenge of improving orientation and register the direction of the moving endoscope, thus creating an optimal visualization for navigated bronchoscopy.

Monitoring of muscle and bone recovery in spinal cord injury patients treated with electrical stimulation using three-dimensional imaging and segmentation techniques: methodological assessment.

Muscle tissue composition accounting for the relative content of muscle fibers and intramuscular adipose and loose fibrous tissues can be efficiently analyzed and quantified using images from spiral computed tomography (S-CT) technology and the associated distribution of Hounsfield unit (HU) values. Muscle density distribution, especially when including the whole muscle volume, provides remarkable information on the muscle condition. Different physiological and pathological scenarios can be depicted using the muscle characterization technique based on the HU values and the definition of appropriate intervals and the association of such intervals to different colors. Using this method atrophy, degeneration, and restoration in denervated muscle undergoing electrical stimulation treatments can be clearly displayed and monitored. Moreover, finite element methods are employed to calculate Young's modulus on the patella bone and to analyze correlation between muscle contraction and bone strength changes. The reliability of this tool though depends on S-CT assessment and calibration. To assess imaging quality and the use of HU values to display muscle composition, different S-CT devices are compared using a Quasar body scanner. Density distributions and volumes of various calibration elements such as lung, polyethylene, water equivalent, and trabecular and dense bone are measured with different scanning protocols and at different points of time. The results show that every scanned element undergoes HU variations, which are greater for materials at the extremes of the HU scale, such as dense bone and lung inhale. Moreover, S-CT scanning with low tube voltages (80 KV) produces inaccurate HU values especially in bones. In conclusion, 3-D modeling techniques based on S-CT scanning is a powerful follow-up tool that may provide structural information at the millimeter scale, and thus may drive choice and timing to validate rehabilitation protocols.

Airway Segmentation and Centerline Extraction from Thoracic CT - Comparison of a New Method to State of the Art Commercialized Methods.

INTRODUCTION: Our motivation is increased bronchoscopic diagnostic yield and optimized preparation, for navigated bronchoscopy. In navigated bronchoscopy, virtual 3D airway visualization is often used to guide a bronchoscopic tool to peripheral lesions, synchronized with the real time video bronchoscopy. Visualization during navigated bronchoscopy, the segmentation time and methods, differs. Time consumption and logistics are two essential aspects that need to be optimized when integrating such technologies in the interventional room. We compared three different approaches to obtain airway centerlines and surface. METHOD: CT lung dataset of 17 patients were processed in Mimics (Materialize, Leuven, Belgium), which provides a Basic module and a Pulmonology module (beta version) (MPM), OsiriX (Pixmeo, Geneva, Switzerland) and our Tube Segmentation Framework (TSF) method. Both MPM and TSF were evaluated with reference segmentation. Automatic and manual settings allowed us to segment the airways and obtain 3D models as well as the centrelines in all datasets. We compared the different procedures by user interactions such as number of clicks needed to process the data and quantitative measures concerning the quality of the segmentation and centrelines such as total length of the branches, number of branches, number of generations, and volume of the 3D model. RESULTS: The TSF method was the most automatic, while the Mimics Pulmonology Module (MPM) and the Mimics Basic Module (MBM) resulted in the highest number of branches. MPM is the software which demands the least number of clicks to process the data. We found that the freely available OsiriX was less accurate compared to the other methods regarding segmentation results. However, the TSF method provided results fastest regarding number of clicks. The MPM was able to find the highest number of branches and generations. On the other hand, the TSF is fully automatic and it provides the user with both segmentation of the airways and the centerlines. Reference segmentation comparison averages and standard deviations for MPM and TSF correspond to literature. CONCLUSION: The TSF is able to segment the airways and extract the centerlines in one single step. The number of branches found is lower for the TSF method than in Mimics. OsiriX demands the highest number of clicks to process the data, the segmentation is often sparse and extracting the centerline requires the use of another software system. Two of the software systems performed satisfactory with respect to be used in preprocessing CT images for navigated bronchoscopy, i.e. the TSF method and the MPM. According to reference segmentation both TSF and MPM are comparable with other segmentation methods. The level of automaticity and the resulting high number of branches plus the fact that both centerline and the surface of the airways were extracted, are requirements we considered particularly important. The in house method has the advantage of being an integrated part of a navigation platform for bronchoscopy, whilst the other methods can be considered preprocessing tools to a navigation system.

Muscle, tendons, and bone: structural changes during denervation and FES treatment.

OBJECTIVES: This paper describes a novel approach to determine structural changes in bone, muscle, and tendons using medical imaging, finite element models, and processing techniques to evaluate and quantify: (1) progression of atrophy in permanently lower motor neuron (LMN) denervated human muscles, and tendons; (2) their recovery as induced by functional electrical stimulation (FES); and (3) changes in bone mineral density and bone strength as effect of FES treatment. METHODS: Briefly, we used three-dimensional reconstruction of muscle belly, tendons, and bone images to study the structural changes occurring in these tissues in paralysed subjects after complete lumbar-ischiadic spinal cord injury (SCI). These subjects were recruited through the European project RISE, an endeavour designed to establish a novel clinical rehabilitation method for patients who have permanent and non-recoverable muscle LMN denervation in the lower extremities. This paper describes the use of segmentation techniques to study muscles, tendons, and bone in several states: healthy, LMN denervated-degenerated but not stimulated, and LMN denervated-stimulated. Here, we have used medical images to develop three-dimensional models and advanced imaging, including computational tools to display tissue density. Different tissues are visualized associating proper Hounsfield intervals defined experimentally to fat, connective tissue, and muscle. Finite element techniques are used to calculate Young's modulus on the patella bone and to analyse correlation between muscle contraction and bone strength changes. RESULTS: These analyses show restoration of muscular structures, tendons, and bone after FES as well as decline of the same tissues when treatment is not performed. This study suggests also a correlation between muscle growth due to FES treatment and increase in density and strength in patella bone. CONCLUSION: Segmentation techniques and finite element analysis allow the study of the structural changes of human skeletal muscle, tendons, and bone in SCI patient with LMN injury and to monitor effects and changes in tissue composition due to FES treatment. This work demonstrates improved bone strength in the patella through the FES treatment applied on the quadriceps femur.