Current Medical Imaging Reviews (v.10, #4)

Extended-Field-of-View (EFOV) ultrasound (US) generates panoramic ultrasound images based on a procedure of image registration applied to a sequence of collected 2D B-scans. In order to improve the imaging accuracy, we propose a novel image registration method combining scale invariant feature transform (SIFT) and random sample consensus (RANSAC) algorithm for the EFOV sonography. Meanwhile, due to the large amount of image data to be processed, implementation of the sequential algorithm based on the SIFT+ RANSAC is time-consuming. To this end, the technology of distributed data processing is employed and an efficient parallel computation method is designed for imaging human musculoskeletal tissues. The experimental results show that the proposed algorithm for EFOV US can produce panoramic images with improved accuracy in comparison with conventional method, especially when the rotations among the captured images are relatively large. In addition, the proposed parallel method significantly speeds up the generation process of panorama in comparison with the serial method, indicating good merit for clinical applications.

Advances in muscle imaging have led to an increasing number of studies relating non-invasive measurements of muscle-tendon complex architecture parameters. Ultrasonagraphy has been shown to be a feasible method to measure muscle morphological changes after neurological diseases such as stroke, cerebral palsy, and spinal cord injury, thus, may help to enhance the understanding of the mechanism underlying the impaired motor function by the muscle level as well as to evaluate the functional improvement of the affected muscle after an intervention program.

Architectural Changes of Thigh Muscles in Patients with Subacute Stroke after Body Weight Support Treadmill Training by Huijing Hu, Yanjun Wang, Xiaoyun Wang, Li Ding, Chuhuai Wang, Le Li, Dan Tang (252-258).
Body weight support treadmill training (BWSTT) can improve motor function of lower limb in stroke patients, but it is not clear the underlying biomechanical contributors to these improvements. The purpose of this study was to evaluate changes of thigh muscle architecture parameters after stroke and compare the effect of BWSTT and traditional walking training at muscle fascicle level by using ultrasonography. This study showed that there are considerable changes in the thigh muscle architecture poststroke, which may contribute directly to muscle weakness and impaired motor functions in stroke survivors. BWSTT can improve the motor function of subacute stroke patients by change the muscle architecture and it is feasible and more effective than conventional gait training with regard to clinical scales. In addition, muscle ultrasound is an excellent tool for quantifying muscle changes in stroke patients.

Since tendons store and release elastic energy, changes in tendon length are important in the performance of human movements. Various methods have been used for evaluating changes in the Achilles tendon length in both static and dynamic conditions. However, thus far, a direct measurement of changes in the Achilles tendon length during dynamic movements has not been performed. In this review article, we discuss the availability of a new method for measuring the Achilles tendon length, which can be potentially applied to dynamic movements due to high time resolution. In this method, both ends of the Achilles tendon were detected using ultrasonographic images. In addition, the path of the Achilles tendon was tracked by placing markers on the skin over the Achilles tendon. Using the three-dimensional coordinates of these markers and the ultrasonographic images, the Achilles tendon length was calculated at 20° dorsiflexion, 0° plantar flexion, and 20° plantar flexion. For this new method, high repeatability (day-to-day) and validity (compared to the Achilles tendon length obtained by magnetic resonance imaging that is considered the golden standard) were confirmed. Therefore, we consider that it would be useful for measuring the Achilles tendon length. Further, since this method allows sufficient time resolution unlike the magnetic resonance imaging method, it would allow the direct measurement of the Achilles tendon length during not only static but also dynamic conditions. This method is expected to improve our understanding of the contribution of the Achilles tendon to the performance of human movements.

Degenerative Changes in Articular Cartilage of Human Femoral Head Assessed Using Quantitative Ultrasonography: A Preliminary Study by Z.W. Liu, Z.H. Chen, Q.Y. Pan, P.F. Ye, Q. Wang, Q.J. Feng, Q.H. Huang, W.F. Chen (266-271).
Osteoarthritis (OA) is a progressive musculoskeletal disease which leads to chronic pain and functional impairment of the involved joint and negatively affects life quality. Degeneration of articular cartilage is one of main OA changes at tissue level. Quantitative ultrasound imaging (QUI) has been developed as a potential technique for evaluation of cartilage quality and diagnosis of OA. The aims of this study are to quantitatively assess the healthy and OA cartilage of human femoral head using QUI and to provide experimental data for future clinical studies. The cartilage samples of femoral head were prepared from human hip joint after patients were performed with joint replacement surgery. Four quantitative parameters including ultrasound roughness index (URI), reflection coefficient (RC), attenuation coefficient (α), cartilage thickness (h) were extracted from ultrasound signals acquired using Sonix RP diagnostic ultrasound system. It was found that in comparison with healthy cartilage, URI and α of the OA cartilage significantly increased (URI: from 59.56±16.17?m to 117.83±28.22?m; α: from 11.95±0.87 to 17.31±3.07, p < 0.05), whereas RC and cartilage thickness significantly decreased (RC: from 37.48±3.57 to 25.57±5.59; h: from 1.02±0.08 to 0.61±0.09, p < 0.05). In addition, the preliminary results indicated that the use of two of these parameters could classify cartilage samples into health and OA groups. Ultrasonic characteristics reflect the changes not only in the cartilage surface and but also in the whole tissue layer. This study may provide useful information for the quantitative ultrasonic diagnosis of OA in the hip joint in further studies.

The aim of this study is to perform a systematic review and meta-analysis of the diagnostic value of 320-slice coronary computed tomography (CT) angiography in the diagnosis of coronary artery disease when compared to invasive coronary angiography. A search of different databases was conducted to identify studies investigating the diagnostic value of 320-slice coronary CT angiography. Sensitivity, specificity, positive and negative predictive value estimates pooled across studies were tested using a fixed effects model and analysed at patient-, vessel- and segment-based assessment. Twelve studies comprising 1592 patients (median, 63 patients, range, 37-240 patients) with a total of 2974 vessels and 21623 segments met selection criteria for inclusion in the analysis. Patients with a high prevalence of coronary artery disease were included in more than 70% of these studies. The mean values and 95% confidence interval (CI) of sensitivity, specificity, positive predictive value and negative predictive value of 320-slice coronary CT angiography were 96.3% (95% CI: 92.9%, 99.8%), 86.4% (95% CI: 77.8%, 94.9%), 89.6% (95% CI: 85.6%, 93.6%) and 93.2% (95% CI: 84.1%, 100%), at patientbased analysis; 91.8% (95% CI: 85.8%, 97.8%), 95.4% (95% CI: 93.6%, 97.1%), 85.9% (95% CI: 79.7%, 92%) and 97.4% (95% CI: 95.9%, 99.1%), at vessel-based analysis; 86.2% (95% CI: 81.8%, 90.6%), 96.5% (95% CI: 95.2%, 98%), 79.9% (95% CI: 75.3%, 84.6%) and 97.8% (95% CI: 96.7%, 99%), at segment-based analysis, respectively. The mean effective dose of 320-slice coronary CT angiography was 10.5 mSv (95% CI: 6.1, 14.8 mSv). Diagnostic value of 320-slice coronary CT angiography was not affected by different heart rates and calcium scores (p>0.05). This analysis shows that 320-slice coronary CT angiography has high diagnostic value in patients with high coronary artery disease prevalence. Relatively high radiation dose is mainly due to inclusion of patients with high heart rates and without using the advanced dose-reduction techniques, thus, further dose-saving strategies should be implemented to minimise the resultant radiation dose.

Invention of diffusion imaging has empowered the neuro-scientists with maps of microscopic structural information that could be taken in vivo. Different diffusion models have been proposed since the inception of the diffusion tensor imaging. Diffusion models have been mainly used for visualizing the brain tissues as precise as possible. However, information about underlying structure of the fiber structures is required for developing precise biomarkers for diseases. The present research aims reviewing diffusion models based on their ability in determining fibers' underlying structure and how these models could be improved. Diffusion modelling methods will be categorized, based on how they model the diffusion, into two main categories namely parametric and non-parametric methods. It will be discussed how modelling assumptions and other strategies could help in developing precise biomarkers. Furthermore, different biomarkers that have been proposed for determining common pathologies of neurodegenerative diseases will be briefly reviewed.

In recent years a great work of the research in the field of medical imaging was focused on the brain tumor segmentation. In this paper, a novel region based active contour model for Magnetic Resonance Images (MRIs) brain tumor segmentation based on a level set origination is proposed and implemented. The image intensities are explained based on the Gaussian distributions through diverse means and variances. The attained local mean and variances are defined as variables and the Moore Gaussian distributions are described by the level set function. The energy minimization is attained by the curve evolution of level set and the approximation of the local intensity means and variances, it is an iterative process. To handle the intensity inhomogeneities and noise, the means and variances are measured as spatially varying functions. The tumor segmentation is an important early phase to solve the segmentation problem effectively. Hybrid Median Filter (HMF) is used to preserve the edges. Also, Sussman boundary condition is explored to accurately extract the tumor portions rather than the unwanted segmentations. The number of iterations used in this novel framework is quite lesser than the existing approach. Hence, the time taken for proposed tumor segmentation technique is also lesser than the existing method. The proposed system Gaussian Distribution with Level Set Method (GD-LSM) results accurate segmentation, sensitivity and specificity outcomes.

The study of optospectral techniques for the non-invasive, in vivo diagnosis of skin diseases has intensified in the last years. Optical diagnosis methods have already started to prove their ability to reveal specific skin functions and to identify skin lesions and their various stages, allowing for the early diagnosis of skin diseases and monitoring of their treatments. At the moment, these techniques have great inter and intra-patient variations, which could be overcome by the use of combined optical techniques, assuring greater accuracy and complementary information, and thus, entering the mainstream of medical practice. After a brief review concerning light-induced fluorescence spectroscopy (LIFS) and optical coherence tomography (OCT) methods, the article intends to present the benefits of applying a combination of both methods for improved diagnostic accuracy in the case of both benign and malignant disorders of the skin.