Soft tissue non-Hodgkin lymphoma of shoulder in a HIV patient: a report of a case and review of the literature

The risk of developing lymphoma is greatly increased in HIV infection. Musculoskeletal manifestations of the human immunodeficiency virus (HIV) are common and are sometimes the initial presentation of the disease. Muscle, bone, and joints are involved by septic arthritis, myopathies and neoplasms. HIV-related neoplastic processes that affect the musculoskeletal system include Kaposi's sarcoma and non-Hodgkin's lymphoma, the latter being mainly localized at lower extremities, spine and skull

A continuous description of intervertebral motion by means of spline interpolation of kinematic data extracted by videofluoroscopy

In vivo analysis of intervertebral kinematics provides useful information about spinal disorders and performance of disk prostheses. Diagnosis of intervertebral instability is based on measurement of abnormal range of segmental motion in sagittal plane through functional flexion-extension radiography; however, this concise measure does not take into account the progression of segmental motion in between flexion and extension extremes. Fluoroscopy can support analysis of intervertebral kinematics during patient's motion with an acceptable X-ray dose. A spline-based method designed for a continuous-time description of intervertebral motion extracted by videofluoroscopy is proposed. Fluoroscopic sagittal sequences of lumbar spine were processed by an automated method based on template matching to track vertebrae. A smoothing spline interpolation of the estimated intervertebral kinematic data was performed and a continuous-time description of segmental rotation and translation was obtained; the smoothing parameter was chosen both to preserve motion and to reduce noise. Concise measurements were extracted by the continuous-time kinematics and compared with standard clinical measurements of intervertebral sagittal rotation and translation. The trajectory of instantaneous center of rotation, never presented before for in vivo spinal segments, was provided and compared with standard measurements of the finite center of rotation. Results showed a good agreement with standard clinical measurements: on average, absolute differences resulted 0.74. degree for sagittal rotation, 0.59. mm for translation and 1.02. mm for the x- and y-position of center of rotation. The proposed method offers an effective technique for the continuous-time description of intervertebral motion, maintaining standard clinical measurements for diagnosis of lumbar instability

A comparison of denoising methods for X-ray fluoroscopic images

Fluoroscopic images exhibit severe signal-dependent quantum noise, due to the reduced X-ray dose involved in image formation, that is generally modelled as Poisson-distributed. However, image gray-level transformations, commonly applied by fluoroscopic device to enhance contrast, modify the noise statistics and the relationship between image noise variance and expected pixel intensity. Image denoising is essential to improve quality of fluoroscopic images and their clinical information content. Simple average filters are commonly employed in real-time processing, but they tend to blur edges and details. An extensive comparison of advanced denoising algorithms specifically designed for both signal-dependent noise (AAS, BM3Dc, HHM, TLS) and independent additive noise (AV, BM3D, K-SVD) was presented. Simulated test images degraded by various levels of Poisson quantum noise and real clinical fluoroscopic images were considered. Typical gray-level transformations (e.g. white compression) were also applied in order to evaluate their effect on the denoising algorithms. Performances of the algorithms were evaluated in terms of peak-signal-to-noise ratio (PSNR), signal-to-noise ratio (SNR), mean square error (MSE), structural similarity index (SSIM) and computational time. On average, the filters designed for signal-dependent noise provided better image restorations than those assuming additive white Gaussian noise (AWGN). Collaborative denoising strategy was found to be the most effective in denoising of both simulated and real data, also in the presence of image gray-level transformations. White compression, by inherently reducing the greater noise variance of brighter pixels, appeared to support denoising algorithms in performing more effectively. © 2012 Elsevier Ltd. All rights reserve

Advanced template matching method for estimation of intervertebral kinematics of lumbar spine.

Diagnosis of low back pain and other degenerative spinal pathologies can be extremely difficult and, so far, there are not accepted standards. In general, such pathologies are associated with alteration of mechanical properties of spine and, in particular, with the instability of spinal motion. Intervertebral kinematics can be a valuable, objective method to assess the functionality of spinal segments. Fluoroscopic imaging system can provide continuous screening of lumbar tracts during patient’s motion, with an acceptable low X-ray dose. Estimation of intervertebral kinematics relies on accurate recognition of vertebrae positions throughout the fluoroscopic sequence: specific vertebrae features are identified and tracked either by manual selection or by automated methods. This study presents a new method of vertebra tracking, based on image template matching of the contour of the vertebral body for an accurate intervertebral kinematics analysis. An image gradient operator was utilized to obtain the vertebral contours; it operates after an edge-preserving smoothing filter designed to reduce low dose X-ray image noise. Once a template is defined for each vertebra, this is used to determine the best vertebral location in each image throughout the fluoroscopic sequence. Accuracy of the proposed method was tested using images of a calibration model. Average error achieved for the intervertebral angle is of the order of 0.4◦ and approximately 2 mm for the intervertebral centre of rotation. Five fluoroscopic lumbar sequences of healthy volunteers undergoing passive flexion–extension motion were processed. The intervertebral kinematics was compared with other methods (automated and manual) by an estimation of measurement error. Results showed that the current method provides a better representation of the evolution over time of kinematic parameters. In particular, root mean square differences between the current method and a manual selection procedure performed by an experienced and trained clinician resulted 1.3◦ for the intervertebral angles and 0.9 mm for the intervertebral trajectory. The proposed method provides an effective, automated and objective technique for estimation of intervertebral kinematics of lumbar spine

Automatic vertebra tracking through dynamic fluoroscopic sequence by smooth derivative template matching

Diagnosis of the underlying causes of widespread spinal pathologies such as back pain and whiplash remains problematic. Many studies suggest that segmental instability may occur and that the study of the intervertebral kinematics can be a valuable, objective method to assess spinal segment functionality. Direct measurement of the intervertebral kinematics results very invasive and unpractical; as alternative analysis of dynamic videofluoroscopic can provide intervertebral kinematic data of lumbar and cervical spinal tracts during unconstrained patient motion, with an acceptable low X-ray dose. Estimation of the kinematics relies on accurate recognition of vertebra positions and rotations on each radiological frame; this can be achieved identifying specific feature points or landmarks, but manual selection results tedious and imprecise. The aim of this work is to present an improved procedure and automatic identification of vertebra motion. By opportunely processing the radiological sequences by using smoothed derivative operators the main vertebral body outlines results enhanced; thus, procedures of template matching for vertebra location become more accurate. Furthermore, data interpolation provided sub-pixel accuracy. Kinematic data, obtained by processing real sagittal fluoroscopic sequences of the lumbar spine, were tested against results of previous studies obtained by manual identification and other methods. Time-evolution of intervertebral kinematic parameters resulted less variable than the other methods; root mean square differences and standard deviations were computed. Vertebra trajectories were interpolated by smoothing cubic spline and instantaneous speed and acceleration were computed. Vertebra speed and acceleration resulted more stable, smooth and in accordance with the actual motion preformed by patient

Vertebrae tracking through fluoroscopic sequence: A novel approach

In-vivo evaluation of intervertebral kinematics can provide precious information for widespread spinal pathologies such as back pain, whiplash, that still lack of certain diagnoses. Analysis of fluoroscopic sequences screening spine tracts (e.g. lumbar, cervical) during unconstrained patient motion can be used to estimate vertebrae and segmental motion: even if limited, the 2D analysis can be employed to study motion onto sagittal plane. Estimation of vertebral kinematics relies on recognition of vertebrae position and rotation on each radiological frame; this can be achieved identifying specific feature points or landmarks. Manual selection results tedious and imprecise, automatic vertebrae recognition can be based on image template matching. This study proposes a particular template matching that uses smoothed image derivatives, which enhances main vertebral body outline. Vertebra location result more accurate and precise with respect to previous techniques. Results were tested against known data of a reference calibration model: the root mean square error resulted 0.2 degree for vertebral angles and 0.3 mm for vertebra positions. A further comparison was performed using previous findings obtained by processing real sagittal, lumbar fluoroscopic sequences: the root mean square error resulted 1.2 degree for vertebral angles and 0.8 mm for vertebra position