T2*-Mapping of Knee Cartilage in Response to Mechanical Loading in Alpine Skiing: A Feasibility Study.

PURPOSE: This study intends to establish a study protocol for the quantitative magnetic resonance imaging (qMRI) measurement of biochemical changes in knee cartilage induced by mechanical stress during alpine skiing with the implementation of new spring-loaded ski binding. METHODS: The MRI-knee-scans (T2*-mapping) of four skiers using a conventional and a spring-loaded ski binding system, alternately, were acquired before and after 1 h/4 h of exposure to alpine skiing. Intrachondral T2* analysis on 60 defined regions of interest in the femorotibial knee joint (FTJ) was conducted. Intra- and interobserver variability and relative changes in the cartilage T2* signal and thickness were calculated. RESULTS: A relevant decrease in the T2* time after 4 h of alpine skiing could be detected at the majority of measurement times. After overnight recovery, the T2* time increased above baseline. Although, the total T2* signal in the superficial cartilage layers was higher than that in the lower ones, no differences between the layers in the T2* changes could be detected. The central and posterior cartilage zones of the FTJ responded with a stronger T2* alteration than the anterior zones. CONCLUSIONS: For the first time, a quantitative MRI study setting could be established to detect early knee cartilage reaction due to alpine skiing. Relevant changes in the T2* time and thus in the intrachondral collagen microstructure and the free water content were observed.

Incidence of anatomical variations according to the International Frontal Sinus Anatomy Classification (IFAC) and their coincidence with radiological sings of opacification.

BACKGROUND: The endonasal access to the frontal recess and sinus may be complicated by a variety of anatomical variations. Previous classifications of these variants were characterized by proper names or position information without anatomical reference. The IFAC is intended to simplify the classification of anatomical variations of the frontoethmoidal complex. The aim of this study was to analyse a representative number of sinus CT scans to assess the incidence of anatomical variations according to the IFAC and to compare the results with previous classifications. In addition, the coincidence of complex anatomical variations and radiological sings of opacification was investigated. METHODOLOGY/PRINCIPAL: Two hundred and forty-nine sinus CT scans were analysed in multiplanar reconstructions. Exclusion criteria were previous operations on the paranasal sinuses, malignant diseases, and an insufficient image quality. All anatomical variants were analysed according to the IFAC criteria. In addition, the coincidence of radiological sings of opacification and the presence of anatomical variations of the frontal recess and sinus were investigated. RESULTS: The analysis revealed Agger nasi cells in 95% of the CT scans. Supra agger cells (SACs) were detected in 49% and Supra agger frontal cells (SAFCs) in 25% of the data sets. Suprabulla cells (SBCs) were detected in 89% and Supra bulla frontal cells (SBFCs) in 27% of the scans. Supraorbital ethmoid cells (SECs) were detectable in 9% and interfrontal septal cells in 28% of the scans. Despite a partially strong narrowing of the frontal recess, no increased occurrence of radiological sings of opacification could be detected (p > 0.05). CONCLUSIONS: Anatomical variations in the frontoethmoidal area are very common. According to the IFAC criteria, in 43% of the patients, cells could be detected with pneumatization to or into the frontal sinus. The IFAC is structured more clearly compared to previous classifications due to the anatomical aspect. It represents the most consistent classification regarding surgical planning. Further studies will demonstrate the scientific and clinical value of this classification.

Iterative scatter correction for grid-less skeletal radiography allows improved image quality equal to an antiscatter grid in adjunct with dose reduction: a visual grading study of 20 body donors.

BACKGROUND: Iterative scatter correction (ISC) is a new technique applicable to plain radiography; comparable to iterative reconstruction for computed tomography, it promises dose reduction and image quality improvement. ISC for bedside chest X-rays has been applied and evaluated for some time and has recently been commercially offered for plain skeletal radiography. PURPOSE: To analyze the potential of ISC for plain skeletal radiography with regard to image quality improvement, dose reduction, and replacement for an antiscatter grid. MATERIAL AND METHODS: A total of 385 radiographs with different imaging protocols of the pelvis and cervical spine were acquired from 20 body donors. Radiographs were rated by four radiologists. Ratings were analyzed with visual grading characteristics (VGC) analysis. The area under the VGC curve was used as a measure of difference in image quality. RESULTS: Without ISC, the grid-less images were rated significantly worse than their grid-based counterparts (0.389, P = 0.005); adding ISC made image quality equal (0.498; P = 0.963). In grid-less imaging, reduction of dose by 50% led to significant image quality impairment (0.415, P = 0.001); this was fully counterbalanced when ISC was added (0.512; P = 0.588). CONCLUSION: ISC for plain skeletal radiography has the ability to replace the antiscatter grid without image quality impairment, to improve image quality in grid-less imaging, and to reduce patient radiation dose by 50% without substantial loss in image quality.

Characteristic morphological patterns within adolescent idiopathic scoliosis may be explained by mechanical loading.

PURPOSE: Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine which exhibits morphological changes during growth. The goal of this study was to identify morphological patterns that could be explained by different loading patterns for AIS. METHODS: Computed tomography data of 21 patients with diagnosed AIS and 48 patients without any visual spinal abnormalities were collected prospectively. The bony structures were reconstructed, and landmarks were placed on characteristic morphological points on the spine. Multiple morphological parameters were calculated based on the distances between the landmarks. The intra- and inter-observer variability for each parameter was estimated. Differences between healthy and scoliotic spines were statistically analysed using the t test for unpaired data, with a significance level of α = 0.01. RESULTS: Within the healthy group, an out-of-plane rotation of the vertebrae in the transverse plane was measured (2.6° ± 4.1° at T2). Relating the length of the spinal curvature to the T1-S1 height of the spine revealed that scoliotic spines were significantly longer. However, the endplate area in the AIS group was significantly smaller once compared to the curvature length. The relation between the left and right pedicle areas varied between 2.5 ± 0.79 and 0.4 ± 0.19, while the ratio of the facet articular surfaces varied within 2.3 ± 0.5 and 0.5 ± 0.2. CONCLUSIONS: This study identified a certain morphological pattern along the spine, which reveals a distinct load path prevalent within AIS. The data suggested that the spine adapts to the asymmetric load conditions and the spine is not deformed by asymmetric growth disturbance. These slides can be retrieved under Electronic Supplementary Material.

Is intervertebral disc degeneration related to segmental instability? An evaluation with two different grading systems based on clinical imaging.

Background Several in vitro studies investigated how degeneration affects spinal motion. However, no consensus has emerged from these studies. Purpose To investigate how degeneration grading systems influence the kinematic output of spinal specimens. Material and Methods Flexibility testing was performed with ten human T12-S1 specimens. Degeneration was graded using two different classifications, one based on X-ray and the other one on magnetic resonance imaging (MRI). Intersegmental rotation (expressed by range of motion [ROM] and neutral zone [NZ]) was determined in all principal motion directions. Further, shear translation was measured during flexion/extension motion. Results The X-ray grading system yielded systematically lesser degeneration. In flexion/extension, only small differences in ROM and NZ were found between moderately degenerated motion segments, with only NZ for the MRI grading reaching statistical significance. In axial rotation, a significant increase in NZ for moderately degenerated segments was found for both grading systems, whereas the difference in ROM was significant only for the MRI scheme. Generally, the relative increases were more pronounced for the MRI classification compared to the X-ray grading scheme. In lateral bending, only relatively small differences between the degeneration groups were found. When evaluating shear translations, a non-significant increase was found for moderately degenerated segments. Motion segment segments tended to regain stability as degeneration progressed without reaching the level of statistical significance. Conclusion We found a fair agreement between the grading schemes which, nonetheless, yielded similar degeneration-related effects on intersegmental kinematics. However, as the trends were more pronounced using the Pfirrmann classification, this grading scheme appears superior for degeneration assessment.