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To assess the use of CT with unfolded cylindrical projection (UCP) for rib fracture detection and characterization.The images from 60 polytraumatized patients who underwent whole body CT were evaluated for the presence and characterization of rib fractures (displaced or not, single or multiple). Two readers independently evaluated conventional CT images and UCP images in two readout sessions at least one month apart. All readouts were timed. A gold standard was established by two radiologists with 12 and 22 years of clinical experience based on the combined analysis of conventional and UCP reformats.Using UCP, the mean evaluation time was 27%-54% shorter (P = 0.01 and0.0001) while maintaining a comparable diagnostic performance (sensitivity and specificity of 68.4-79.1% and 99.5-99.6% for conventional reformats and 70.6-91.0% and 96.8-97.7% for UCP) and a good reproducibility (Kappa of 0.71). The multiple fracture detection ratio of UCP was similar to that of conventional reformats (80%). There were more false positives and false negatives using UCP and displaced fractures were harder to characterize.UCP yielded a diagnostic performance similar to that of conventional reformats for the detection of rib fractures with a good reproducibility and a noticeable reduction in evaluation time.

To compare the performance of different image reconstruction algorithms in the presence of small metal objects of different sizes and at different dose levels.A fresh bone of bovine femur was drilled with seven drill bits of increasing diameter. CT images with eight different dose levels were acquired and reconstructed with three algorithms: hybrid iterative reconstruction - HIR, Full model-based iterative reconstruction - full MBIR and a single energy metal artifact reduction - SEMAR. Trabecular distortion adjacent to metal was evaluated subjectively with a four-point scale. Edge profile artifacts were evaluated quantitatively by measuring drill bit diameter overestimation and the width of the low-density halo surrounding the drill bit.Trabecular distortion was higher with full MBIR compared to HIR and SEMAR (P 0.0001) and increased with drill bits larger than 1.2 mm and with doses lower than 18.1 mGy.cm. Low-density halos size and drill bit diameter overestimation decreased with full MBIR compared to the other two reconstruction algorithms and with SEMAR compared to HIR (P 0.0001). There was a mean drill bit overestimation of 0.56 ± 0.25 mm for full MBIR versus 0.68 ± 0.09 mm for SEMAR and mean low-density halo diameters of 0.03 mm ± 0.08 for full MBIR versus 0.42 mm ± 0.09 for SEMAR.Algorithm performance is influenced by dose levels and metal object size and no individual algorithm provides the best overall performance. Full MBIR is better in reducing edge artifacts and SEMAR is the best option for larger metal implants and low dose protocols.

The purpose of this prospective study was to ascertain the degree of variation of semi-quantitative and permeability parameters on DCE-MRI of normally appearing striated muscles. Dynamic contrast-enhanced MRI of the right hip was performed in 20 women and 24 men. Mean age was 39.1 ± 12.4 years. Two regions of interest (ROI) were drawn in twelve muscles of anterior, medial and gluteal compartments: a free-form ROI covering the largest muscle section and a smaller elliptical ROI. Semi-quantitative and permeability parameters were calculated using the extended Tofts model. Statistical analysis was performed with a linear mixed model to assess perfusion parameters variation. Intra- and inter-observer agreements were assessed. The intra-observer agreement was considered to be good for free-form ROI (minimum Intra-Class Coefficient (ICC) = 0.72) and moderate for elliptical ROI (minimum ICC = 0.51), while the inter-observer agreement was considered to be bad in both cases (minimum ICC = 0.11). There was a high inter-individual variation in most of the perfusion parameters evaluated. The average coefficients of variation were: Time To Peak = 9%, Area Under the Curve = 44%, Ve = 61%, Kep = 90%, Initial Slope = 99%, and Ktrans = 128%. A considerable variation in resting muscle perfusion parameters was seen. This could lead to errors in the analysis of muscle DCE-MRI studies or oncologic/non oncologic studies using muscle as a referential. Further studies targeted on acquisition protocols and post-processing software are necessary to improve the performance of muscle MR perfusion.

The management of Kienbock's disease is complex and constantly evolving in parallel with progress in the understanding of the pathophysiological mechanisms of this condition. Cross-sectional imaging techniques have an essential role in the diagnosis and prognostic assessment of this disease. CT allows the optimal study of the morpho-structure of lunate bone. MRI makes it possible to study bone marrow viability. As for CT arthrography, it allows to evaluate accurately articular cartilage of the different carpal joints. The evaluation of these different aspects of Kienbock's disease is essential for optimal treatment selection. Cross-sectional imaging also has an interest in post-treatment follow-up, by having a prognostic value and allowing the identification of post-operative complications. The purpose of this article is to review the contribution of cross-sectional imaging in the assessment of Kienbock's disease before and after treatment according to the most common surgical procedures. Pathophysiological mechanisms, predisposing factors, the different classifications and their interests will be discussed.