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Purpose: To compare T2 * relaxation times of the tibiotalar cartilage between professional football players and matched healthy male volunteers.Materials and Methods: Twenty-two ankles of professional football players (24.3 ± 3.8 years) and 20 age- and body mass index-matched healthy individuals (25.6 ± 2.4 years) were investigated. The study protocol consisted of multiplanar T1 -weighted, fat-saturated proton-density weighted (Pdw) and a 3D multiecho T2 * sequence with 22 echo times (4.6-53.6 msec). The articular cartilage was subdivided into six segments. Regions of interest were manually drawn in three zones (lateral, central, medial). Differences and confidence intervals were estimated applying a random effects models. Fixed effects were professional football players versus healthy individuals and areas. The random effect was defined as the person cluster of the different individuals.Results: T2 * values were significantly prolonged in football players compared to male volunteers in all predefined cartilage segments (mean, 17.5 vs. 15.5 msec; P < 0.001). In both groups, the highest relaxation times were found in the lateral zone, with statistically higher relaxation times in professional football players (18.5 vs. 16.5 msec, P = 0.003). Separate evaluation revealed the longest relaxation times in the posterior tibiotalar cartilage, with 21.0 msec for professional football players compared to 19.4 msec for healthy volunteers (P = 0.064).Conclusion: Based on these initial results, T2 * values of the tibiotalar cartilage seem to be elevated in professional football players compared to healthy volunteers. Prospective longitudinal studies should be encouraged to show if these results represent early subtle cartilage lesions prior to clinical manifestation or rather temporary adaptation related to daily high-level loading.Level Of Evidence: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:372-379. [ABSTRACT FROM AUTHOR]

Background:  Throughout the literature, patellofemoral instability (PI) is defined as an increased risk of re-/luxation of the patella within the patellofemoral joint (PFJ). In most patients it is caused by traumatic patella luxation or the existence of a range of predisposing anatomic risk factors leading to an unphysiological movement sequence within the PFJ also known as patellofemoral maltracking. In order to provide an individualized therapy approach, clinical and radiological evaluation of those risk factors of variable magnitude becomes essential. Diagnostic imaging such as magnetic resonance imaging (MRI), plain radiography, and computed tomography (CT) are straightforward diagnostic tools in terms of evaluation and treatment of PI., Method:  In this review we performed a precise analysis of today's literature concerning the radiological evaluation of anatomic risk factors leading to PI. The purpose of the review is to present a logical compilation of the different anatomical risk factors causing PI and provide a straight overview of valuable radiological imaging techniques., Results and Conclusion:  PI is frequently based on a multifactorial disposition. The most relevant predisposing risk factors are trochlea dysplasia, rupture of the medial patellofemoral ligament (MPFL), patella alta, abnormal tibial tubercle to trochlea groove distance (TT-TG), femoral torsion deformities, and genu valgum. Although plain X-rays may provide basic diagnostic value, cross-sectional imaging (MRI, CT) is the standard radiological tool in terms of evaluation and detection of severity of predisposing anatomic variants leading to PI., Key Points:   · Based on today's literature, PI is characterized as an increased risk of patella re-/luxation within the PFJ.. · Underlying anatomic risk factors of variable magnitude mark the pathological cause of PI.. · Modern diagnostic imaging (MRI and CT) permits straightforward diagnosis of the typical features in terms of PI.. · To provide an individualized therapy approach, precise radiological evaluation and determination of the severity of predisposing anatomic anomalies are essential.., Citation Format: · Maas KJ, Warncke ML, Leiderer M et al. Diagnostic Imaging of Patellofemoral Instability. Fortschr Röntgenstr 2021; 193: 1019 - 1033., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

OBJECTIVE. The purpose of this study is to investigate the feasibility of submillisievert CT of the skeletal pelvis of human cadavers using a standard-dose protocol and four different reduced-dose protocols reconstructed with filtered back projection (FBP) and iterative reconstruction (IR). MATERIALS AND METHODS. The pelvis of 25 human cadavers was repeatedly examined using different reduced-dose CT (RDCT) protocols with decreasing reference tube current-exposure time products (RDCT protocol 1, 80 mAs; RDCT protocol 2, 60 mAs; RDCT protocol 3, 40 mAs; and RDCT protocol 4, 10 mAs) and a tube voltage of 120 kV. A standard-dose CT (SDCT) protocol (reference tube current-exposure time product, 100 mAs; tube voltage, 120 kV) used for the same cadavers served as the reference. Raw data were reconstructed using FBP and two increasing levels of IR (IR levels 4 and 6). The image quality and diagnostic acceptability of images of the anterior pelvic ring, acetabulum, and posterior pelvic ring including the sacroiliac joints were evaluated on a 5-point scale. A mixed-effects model for repeated measures was performed. RESULTS. The image quality of all anatomic structures was rated as diagnostically acceptable for all protocols reconstructed with IR, except for 11 cadavers that were imaged using RDCT protocol 4. For reconstructions with FBP, image quality was generally rated lower and was diagnostically acceptable only for images obtained using SDCT and RDCT protocol 1 and 2. RDCT protocol 3 with IR was the RDCT protocol with the largest reduced dose still allowing diagnostically acceptable image quality for all anatomic structures in all cadavers. Compared with SDCT, the RDCT protocols resulted in significantly reduced mean (± SD) effective radiation doses (SDCT, 2.0 ± 0.7 mSv; RDCT protocol 1, 1.6 ± 0.6 mSv; RDCT protocol 2, 1.2 ± 0.4 mSv; RDCT protocol 3, 0.8 ± 0.3 mSv; and RDCT protocol 4, 0.3 ± 0.1 mSv; p = 0.001). CONCLUSION. Diagnostically acceptable submillisievert CT of the skeletal pelvis is feasible using IR. To adhere to the ALARA (as low as reasonably achievable) principle, submillisievert pelvic CT protocols combined with IR should be implemented as part of routine clinical practice.

Purpose: To compare T 2 * relaxation times of the tibiotalar cartilage between professional football players and matched healthy male volunteers., Materials and Methods: Twenty-two ankles of professional football players (24.3 ± 3.8 years) and 20 age- and body mass index-matched healthy individuals (25.6 ± 2.4 years) were investigated. The study protocol consisted of multiplanar T 1 -weighted, fat-saturated proton-density weighted (Pdw) and a 3D multiecho T 2 * sequence with 22 echo times (4.6-53.6 msec). The articular cartilage was subdivided into six segments. Regions of interest were manually drawn in three zones (lateral, central, medial). Differences and confidence intervals were estimated applying a random effects models. Fixed effects were professional football players versus healthy individuals and areas. The random effect was defined as the person cluster of the different individuals., Results: T 2 * values were significantly prolonged in football players compared to male volunteers in all predefined cartilage segments (mean, 17.5 vs. 15.5 msec; P < 0.001). In both groups, the highest relaxation times were found in the lateral zone, with statistically higher relaxation times in professional football players (18.5 vs. 16.5 msec, P = 0.003). Separate evaluation revealed the longest relaxation times in the posterior tibiotalar cartilage, with 21.0 msec for professional football players compared to 19.4 msec for healthy volunteers (P = 0.064)., Conclusion: Based on these initial results, T 2 * values of the tibiotalar cartilage seem to be elevated in professional football players compared to healthy volunteers. Prospective longitudinal studies should be encouraged to show if these results represent early subtle cartilage lesions prior to clinical manifestation or rather temporary adaptation related to daily high-level loading., Level of Evidence: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:372-379., (© 2017 International Society for Magnetic Resonance in Medicine.)