Pulmonary CT Images Research Articles

A strain energy filter for 3D vessel enhancement with application to pulmonary CT images

The traditional Hessian-related vessel filters often suffer from detecting complex structures like bifurcations due to an over-simplified cylindrical model. To solve this problem, we present a shape-tuned strain energy density function to measure vessel likelihood in 3D medical images. This method is initially inspired by established stress-strain principles in mechanics. By considering the Hessian matrix as a stress tensor, the three invariants from orthogonal tensor decomposition are used independently or combined to formulate distinctive functions for vascular shape discrimination, brightness contrast and structure strength measuring. Moreover, a mathematical description of Hessian eigenvalues for general vessel shapes is obtained, based on an intensity continuity assumption, and a relative Hessian strength term is presented to ensure the dominance of second-order derivatives as well as suppress undesired step-edges. Finally, we adopt the multi-scale scheme to find an optimal solution through scale space. The proposed method is validated in experiments with a digital phantom and non-contrast-enhanced pulmonary CT data. It is shown that our model performed more effectively in enhancing vessel bifurcations and preserving details, compared to three existing filters.

Implementation and evaluation of various demons deformable image registration algorithms on a GPU

Online adaptive radiation therapy (ART) promises the ability to deliver an optimal treatment in response to daily patient anatomic variation. A major technical barrier for the clinical implementation of online ART is the requirement of rapid image segmentation. Deformable image registration (DIR) has been used as an automated segmentation method to transfer tumor/organ contours from the planning image to daily images. However, the current computational time of DIR is insufficient for online ART. In this work, this issue is addressed by using computer graphics processing units (GPUs). A gray-scale-based DIR algorithm called demons and five of its variants were implemented on GPUs using the compute unified device architecture (CUDA) programming environment. The spatial accuracy of these algorithms was evaluated over five sets of pulmonary 4D CT images with an average size of 256 × 256 × 100 and more than 1100 expert-determined landmark point pairs each. For all the testing scenarios presented in this paper, the GPU-based DIR computation required around 7 to 11 s to yield an average 3D error ranging from 1.5 to 1.8 mm. It is interesting to find out that the original passive force demons algorithms outperform subsequently proposed variants based on the combination of accuracy, efficiency and ease of implementation.

Cardiac phase-correlated image reconstruction and advanced image processing in pulmonary CT imaging

Image quality in pulmonary CT imaging is commonly degraded by cardiac motion artifacts. Phase-correlated image reconstruction algorithms known from cardiac imaging can reduce motion artifacts but increase image noise and conventionally require a concurrently acquired ECG signal for synchronization. Techniques are presented to overcome these limitations. Based on standard and phase-correlated images that are reconstructed using a raw data-derived synchronization signal, image-merging and temporal-filtering techniques are proposed that combine the input images automatically or interactively. The performance of the approaches is evaluated in patient and phantom datasets. In the automatic approach, areas of strong motion and static areas were well detected, providing an optimal combination of standard and phase-correlated images with no visible border between the merged regions. Image noise in the non-moving regions was reduced to the noise level of the standard reconstruction. The application of the interactive filtering allowed for an optimal adaptation of image noise and motion artifacts. Noise content after interactive filtering decreased with increasing temporal filter width used. We conclude that a combination of our motion-free merging approach and a dedicated interactive filtering procedure can highly improve pulmonary imaging with respect to motion artifacts and image noise.

Pulmonary CT image registration and warping for tracking tissue deformation during the respiratory cycle through 3D consistent image registration

Tracking lung tissues during the respiratory cycle has been a challenging task for diagnostic CT and CT-guided radiotherapy. We propose an intensity- and landmark-based image registration algorithm to perform image registration and warping of 3D pulmonary CT image data sets, based on consistency constraints and matching corresponding airway branchpoints. In this paper, we demonstrate the effectivenss and accuracy of this algorithm in tracking lung tissues by both animal and human data sets. In the animal study, the result showed a tracking accuracy of 1.9 mm between 50% functional residual capacity (FRC) and 85% total lung capacity (TLC) for 12 metal seeds implanted in the lungs of a breathing sheep under precise volume control using a pulmonary ventilator. Visual inspection of the human subject results revealed the algorithm's potential not only in matching the global shapes, but also in registering the internal structures (e.g., oblique lobe fissures, pulmonary artery branches, etc.). These results suggest that our algorithm has significant potential for warping and tracking lung tissue deformation with applications in diagnostic CT, CT-guided radiotherapy treatment planning, and therapeutic effect evaluation.

TH‐C‐342‐03: Quantitative Medical Image Analysis for Early Detection, Diagnosis, Outcome Prediction, and Treatment

Medical imaging and image analysis has revolutionized the patient care as well as many research activities in biology and healthcare. Stet‐of‐the‐art methods and approaches for medical image segmentation, quantitative analysis, and their use for computer‐aided diagnosis and disease progression prediction will be the main target of this presentation. Special focus will be given to several high‐complexity projects in the areas of coronary image analysis via fusion of intravascular ultrasound and angiography, coronary plaque analysis, plaque progression prediction, cardiovascular risk factor assessment via analysis of carotid and brachial ultrasound images, pulmonary CT image analysis, computer‐aided diagnosis of congenital aortic disease, cartilage MR image analysis, and liver surgery planning. The talk will be accompanied by live demonstrations of the software tools developed for the above‐referenced purposes.

Osler-Weber-Rendu syndrome

The attached image ([Fig. 1][1]) is intended to complement the pulmonary radiography and CT imaging that accompany the report of a case of hereditary hemorrhagic telangiectasia described by Narinder Pal Singh and colleagues.[1][2] It is this observer's experience that telangiectasia have a

Utility of CT findings on diagnosis of occupational lung disease

Introduction We experienced two occupational lung diseases on a different situation in military training. The purpose of this study was to investigate the use of CT images for inhaled pulmonary edema from the standpoint of early diagnosis and assessment of severity. Materials and methods Case 1: Two soldiers who used the rust proofing sprays and dust removal sprays for the daily maintenance of their arms suffered from severe lung edema. Case 2: Four soldiers suffered from severe dyspnea because they drilled in the field where many smoke canisters were used. We evaluated these patients by clinical symptoms, laboratory data, pulmonary function test, chest X-P and CT images. Results Case 1: Their chest CT scan showed bilateral infiltration mainly in the upper lung field. Steroid pulse treatment was used for recovery. Seven days later, their chest X-P showed almost normal. Case 2: Their chest radiographs showed mild infiltrative shadows. Their chest CT scan showed bilateral ground grass attenuation with the peripheral lung spared. They recovered gradually by steroid therapy. Seven days later, mild abnormal shadow was observed in their chest CT images. Discussion In the literature, chest CT scan showed diffused ground glass opacities mainly in the upper lung field of inhaled pulmonary edema patients. The peripheral part of the lungs was kept normal excluding the seriously injured cases. These findings are the same as those in our cases. When differential diagnosis was needed, we considered chest CT scan especially useful. The findings of CT scan are useful not only for the diagnosis of inhaled pulmonary edema but also for determining the severity of lung injury.

Thin-section CT of the lung: influence of 0.5-s gantry rotation and ECG triggering on image quality.

The aim of this study was to determine if ECG triggering and a shorter acquisition time of 0.5-s rotation decrease cardiac motion artifacts of thin-section CT of the lung. In 25 patients referred for thin-section thoracic CT, 1-mm thin-section slices were performed with a scanning time of 0.5 s with ECG gating, 0.5 s and 1 s during the diastolic phase of the heart at five identical anatomical levels from the aortic arch to lung basis. At each anatomical level and for each lung, cardiac motion artifacts were graded independently on a four-point scale by three readers. Patients were divided into two groups according to their heart rate. A four-way analysis of variance was used to assess differences between the three modalities. Mean cardiac motion artifacts scores were rated 1.23+/-0.02, 1.47+/-0.02, and 1.79+/-0.02, at 0.5 s with ECG gating, 0.5 s without ECG gating, and 1 s, respectively (F=139, p<0.0001). At the four anatomical levels below the aortic arch, the left lung scores were greater than the right lung score for the three modalities. For the modality 0.5 s with ECG gating no difference of scores was found between patients grouped according to their cardiac frequency. The 0.5-s gantry rotation with or without ECG gating scans reduces cardiac motion artifacts on pulmonary thin-section CT images and is mainly beneficial for the lower part of the left lung.

胸部CTにおける吸入空気量がCT画像におよぼす影響について

胸部CTにおける吸入空気量がCT画像におよぼす影響について