Conditional Covariances for the Signal Lag Measurements in Fluoroscopic Imaging

In fluoroscopic imaging, we can acquire X-ray image sequences using a flat-panel dynamic detector. However, lag signals from previous frames are added to the subsequently acquired images and produce lag artifacts. The lag signals also inflate the measured noise power spectrum (NPS) of a detector. In order to correct the measured NPS, the lag correction factor (LCF) is generally used. However, the nonuniform temporal gain (NTG), which is from inconsistent X-ray sources and readout circuits, can significantly distort the LCF measurements. In this paper, we propose a simple scheme to alleviate the NTG problem in order to accurately and efficiently measure the detector LCF. We first theoretically analyze the effects of NTG, especially on the correlation-based LCF measurement methods, where calculating the correlation coefficients are required. In order to remove the biases due to NTG, a notion of conditional covariance is considered for unbiased estimates of the correlation coefficients. Experiments using practical X-ray images acquired from a dynamic detector were conducted. The proposed approach could yield accurate LCF values similarly to the current approaches of the direct and U-L corrections with a low computational complexity. By calculating the correlation coefficients based on conditional covariance, we could obtain accurate LCF values even under the NTG environment. This approach does not require any preprocessing scheme of the direct or U-L correction and can provide further accurate LCF values than the method of IEC62220-1-3 does.

Characterisation of hemidiaphragm dysfunction using dynamic chest radiography: a pilot study

ObjectivesDynamic chest radiography (DCR) is a novel real-time digital fluoroscopic imaging system that produces clear, wide field-of-view diagnostic images of the thorax and diaphragm in motion, alongside novel metrics on moving structures within the thoracic cavity. We describe the use of DCR in the measurement of diaphragm motion in a pilot series of cases of suspected diaphragm dysfunction.MethodsWe studied 21 patients referred for assessment of diaphragm function due to suspicious clinical symptoms or imaging (breathlessness, orthopnoea, reduced exercise tolerance, and/or an elevated hemidiaphragm on plain chest radiograph). All underwent DCR with voluntary sniff manoeuvres.ResultsParadoxical motion on sniffing was observed in 14 patients, and confirmed in 6 who also underwent fluoroscopy or ultrasound. In 4 patients, DCR showed reduced hemidiaphragm excursion but no paradoxical motion; in 3, normal bilateral diaphragm motion was demonstrated. DCR was quick to perform, well-tolerated in all cases and with no adverse events reported. DCR was achieved in around five minutes per patient, with images available to view by the clinician immediately within the clinical setting.ConclusionDCR is a rapid, well-tolerated and straightforward X-ray technique that warrants further investigation in the assessment of diaphragm dysfunction.

Contrast Agent Mimicking Calculi in Entrapped Calyx. A Report of a Case

Urolithiasis is a common condition, and it represents a large number of hospital visits. Under the term infundibulopelvic dysgenesis, many conditions amongst a spectrum of congenital disorders of the pelvicalyceal system are described. Retrograde intrarenal surgery (RIRS) is an effective and safe treatment modality in the management of urinary system stone disease. Fluoroscopic imaging is a cornerstone in endourology. Herein, we present a case where we diagnosed an obstructed calyx during RIRS for renal calculi and operated on it. In this extraordinary case, contrast agent was trapped in the calyx mimicking a renal stone and that was the reason that we discovered the infundibular stenosis. The patient, 24 h after the operation, left the hospital without any complications reported.

Investigation of Geometric Deformations of The Lumbar Disc During Axial Body Rotations

BackgroundQuantitative data on in vivo vertebral disc deformations are critical for enhancing our understanding of spinal pathology and improving the design of surgical materials. This study investigated in vivo lumbar intervertebral disc deformations during axial rotations under different load-bearing conditions.MethodsTwelve healthy subjects (7 males and 5 females) between the ages of 25 and 39 were recruited. Using a combination of a dual fluoroscopic imaging system (DFIS) and CT, the images of L3-5 segments scanned by CT were transformed into three-dimensional models, which matched the instantaneous images of the lumbar spine taken by a double fluorescent X-ray system during axial rotations to reproduce motions. Then, the kinematic data of the compression and shear deformations of the lumbar disc and the coupled bending of the vertebral body were obtained.ResultsRelative to the supine position, the average compression deformation caused by rotation is between +10% and -40%, and the shear deformation is between 17% and 50%. Under physiological weightbearing loads, different levels of lumbar discs exhibit similar deformation patterns, and the deformation patterns of left and right rotations are approximately symmetrical. The deformation patterns change significantly under a 10 kg load, with the exception of the L3-4 disc during the right rotation.ConclusionThe deformation of the lumbar disc was direction-specific and level-specific during axial rotations and was affected by extra weight. These data can provide new insights into the biomechanics of the lumbar spine and optimize the parameters of artificial lumbar spine devices.

Advances in the Application of the Dual Fluoroscopic Imaging System in Sports Medicine: A Literature Review

The dual fluoroscopic imaging system (DFIS) is a new non-invasive motion analysis system that does not interfere with movement, has high precision and repeatability and is not affected by the errors caused by the relative movement of skin and soft tissues. DFIS has been recently used in the field of sports medicine. This narrative review focuses on relevant literature on the origin, development and mechanism of action of DFIS and summarises the application of DFIS in injury and rehabilitation treatment, such as the reliability of test results; the position relationships of bony structures in the shoulder, lumbar spine, knee joint and ankle joint during exercise and its six degree-of-freedom (6DOF) movement to calculate cartilage deformation, contact area/trajectory and ligament strain. This article puts forward the problems encountered in practice that need to be solved and looks forward to the future applications of DFIS in the field of sports, especially in injury prevention and treatment.

In Vivo Foot and Ankle Kinematics During Activities Measured by Using a Dual Fluoroscopic Imaging System: A Narrative Review

Foot and ankle joints are complicated anatomical structures that combine the tibiotalar and subtalar joints. They play an extremely important role in walking, running, jumping and other dynamic activities of the human body. The in vivo kinematic analysis of the foot and ankle helps deeply understand the movement characteristics of these structures, as well as identify abnormal joint movements and treat related diseases. However, the technical deficiencies of traditional medical imaging methods limit studies on in vivo foot and ankle biomechanics. During the last decade, the dual fluoroscopic imaging system (DFIS) has enabled the accurate and noninvasive measurements of the dynamic and static activities in the joints of the body. Thus, this method can be utilised to quantify the movement in the single bones of the foot and ankle and analyse different morphological joints and complex bone positions and movement patterns within these organs. Moreover, it has been widely used in the field of image diagnosis and clinical biomechanics evaluation. The integration of existing single DFIS studies has great methodological reference value for future research on the foot and ankle. Therefore, this review evaluated existing studies that applied DFIS to measure the in vivo kinematics of the foot and ankle during various activities in healthy and pathologic populations. The difference between DFIS and traditional biomechanical measurement methods was shown. The advantages and shortcomings of DFIS in practical application were further elucidated, and effective theoretical support and constructive research direction for future studies on the human foot and ankle were provided.

Retro-patellar approach in telescopic nailing of the tibia in children with osteogenesis imperfecta

Purpose Telescopic intramedullary nailing (TN) has become the main choice of treatment in children with osteogenesis imperfecta (OI). The classical parapatellar tibial nailing technique poses difficulties in maintaining reduction, insertion of the nail and fluoroscopic imaging. Also, deformities of the proximal tibia in relatively small children with OI can be problematic for tibial nailing. In this report, we present the retro-patellar approach in tibial TN of children with OI as an alternative to the classical approach and report the early radiographic and clinical results of our patients. Methods The nail is inserted through a skin incision proximal to the patella, passing inside the patellofemoral joint while the knee is positioned to 15° to 20° of flexion. In total, 30 tibiae of 15 patients had been operated and were reviewed after at least one year of follow-up. Any complications, such as implant failure, joint damage or instability, malunion, nonunion or refracture, were recorded. Results The mean age of our patients was 8.5 years, and the mean follow-up period was 27 months. There were no complaints involving the knee. All patients showed complete union without any implant failure or refracture. We did not observe any nail protrusion, bending or loss of correction during the procedure. Conclusion The retro-patellar approach for tibial TN appears to be safe and effective in patients with OI. Level of Evidence IV