IntroductionThis study aimed to evaluate the impact of varying slice thickness on quantitative values using the Magnetic Resonance Image Compilation (MAGiC) sequence. MethodsIn this retrospective study, 23 healthy subjects underwent the MAGiC sequence (at 3.0 T) with three slice thicknesses: 3 mm (TH3), 4 mm (TH4), and 5 mm (TH5). The T1, T2, and PD values were measured in various knee joint cartilage regions by two experienced radiologists, including the lateral femoral condyle (LFC), lateral tibial plateau (LTP), medial femoral condyle (MFC), medial tibial plateau (MTP), patella (PAT), and trochlea (TRO). The effects of varying slice thicknesses (TH4 vs. TH3 and TH5 vs. TH3) were analyzed using paired t-tests or Wilcoxon signed rank tests, with statistical significance set at P < 0.025. Intra-rater and inter-rater reliability were also assessed. ResultsMeasurements of T1, T2, and PD values demonstrated high intra- and inter-rater reliability. Minimal differences were observed across slice thicknesses for T1WI, T2WI, and PDWI images. T2 and PD values showed little variation, while T1 mapping revealed significant differences. T2 values were consistent across regions, except for the LFC. DiscussionTH4 and TH5 can replace TH3 for knee joint scanning while reducing scan time, with minimal differences in anatomical depiction across sequences. MAGiC technology significantly improves efficiency by acquiring quantitative data in a single scan, demonstrating stable T2 values unaffected by slice thickness, though T1 and PD values are thickness-dependent. This technique holds clinical value for cartilage injury assessment but requires further research on the applicability of multiplanar imaging. ConclusionT2 values obtained with the MAGiC sequence are stable across TH3, TH4, and TH5, allowing for reliable cartilage T2 quantification using TH5 to reduce patient scan time.

BACKGROUND:Ankle cartilage is prone to degeneration due to overuse. Developing a non-invasive MRI technique to detect early running-induced lesions enables timely intervention. PURPOSE:To evaluate the value of the ultrashort echo time magnetization transfer (UTE-MT) sequence in monitoring tibiotalar cartilage changes in amateur marathon runners before and after a marathon. STUDY TYPE:Prospective. SUBJECTS:Thirty amateur marathon runners (25 males, 5 females; range: 24-50 years). SEQUENCE:3D UTE-MT (gradient-echo), 3D UTE-T2* (gradient-echo). ASSESSMENT:MRI scans at three time points: 1 week pre-marathon, 2 days post-marathon, and 4 weeks post-marathon. Medial and lateral tibiotalar cartilage was subdivided into 12 subregions, consisting of anterior, middle, and posterior segments for the tibial and talus parts on each side. The UTE-MTR and UTE-T2* values were measured per subregion at each time point. STATISTICAL TESTS:Repeated measures one-way ANOVA and the Tukey test. p < 0.05 was considered statistically significant. RESULTS:Most cartilage subregions showed decreased UTE-MTR values 2 days post-marathon and increased after 4 weeks. Significant differences in UTE-MTR over time were observed in 9 subregions, including the medial and lateral anterior, middle, and posterior tibial cartilage (MTiA, MTiM, MTiP, LTiA, LTiM, LTiP), the medial and lateral posterior talus regions (MTaP, LTaP), and the medial middle talus cartilage (MTaM). Post hoc tests revealed significant UTE-MTR decreases 2 days post-marathon in all 9 regions (Rate: MTiA: -3.9%; MTiM: -2.8%; MTiP: -3.0%; MTaP: -4.5%; MTaM: -4.2%; LTiA: -3.5%; LTiM: -4.7%; LTiP: -5.8%; LTaP: -6.8%), with significant increases in MTiA (3.7%) and MTaM (4.4%) at 4 weeks. UTE-T2* values rose in most cartilage regions at 2 days post-marathon and continued increasing at 4 weeks. Only MTiP, LTiM, and LTaM showed significant changes. DATA CONCLUSION:This study demonstrates that the UTE-MT sequence enables the quantitative assessment of dynamic changes in tibiotalar joint cartilage after a marathon. LEVEL OF EVIDENCE: 2: TECHNICAL EFFICACY:Stage 1.

To evaluate tibiotalar cartilage changes in amateur marathon runners pre- and post-marathon using 3D ultrashort echo time (UTE) bi-component analysis. Amateur runners were prospectively enrolled and underwent ankle MRI at three time points: pre-marathon, 2 days post-marathon, and 4 weeks post-marathon. UTE component analysis was used to obtain single-component values (T2*M), and bi-component values (short (T2*S) and long T2* component values (T2*L), and short T2* fractions) of cartilage. Sagittal images were analyzed by segmenting tibial and talus cartilage into 12 subregions (medial/lateral, anterior/middle/posterior). Thirty-two runners (26 men, 6 women; mean age, 39.80 ± 6.00 years) were evaluated. UTE component analysis parameters increased in most subregions after running, with T2*M increasing further at 4 weeks, while T2*S, T2*L, and short T2* fractions decreased. Repeated-measures analysis of variance (RM-ANOVA) revealed significant T2*S differences in the middle and posterior medial tibia (MTiM, MTiP), the middle medial talus (MTaM), the anterior, middle, and posterior lateral tibia (LTiA, LTiM, and LTiP), and the middle and posterior lateral talus (LTaM and LTaP) (p < 0.05). Short T2* fractions exhibited significant changes in MTiM, MTiP, MTaM, LTiM, and LTaM (RM-ANOVA, p < 0.05). MTiP, MTaP, LTiM, and LTaM showed significant T2*M changes (RM-ANOVA, p < 0.05). Only LTaM showed significant T2*L changes (Friedman’s rank test, p < 0.05). The T2*S and short T2* fractions from UTE bi-component analysis may be more sensitive than T2*M, offering a promising method for detecting dynamic changes in ankle cartilage following long-distance running. Question Long-distance running causes changes in the tibiotalar articular cartilage. Can UTE component analysis of T2* monitor dynamic changes of tibiotalar articular cartilage non-invasively? Findings T2*S and short T2* fractions of UTE bi-component analysis were superior to single-component analysis in monitoring dynamic changes in ankle cartilage. Clinical relevance This study suggests that the UTE bi-component T2* analysis detects exercise-induced cartilage changes, allowing early matrix assessment in at-risk populations and supporting prevention strategies for athletes.

BACKGROUND:Accurate evaluation of the cartilage anatomy of the knee is helpful for clinical evaluation of the source of knee pain and the classification and treatment of knee osteoarthritis (OA). This study proposes a deep learning model for segmentation of knee articular cartilage in conventional proton density fat-saturated MRI sequences to assess cartilage morphology for subsequent injury grading. METHODS:This retrospective study was conducted at two radiology centers, involving 254 knees from 254 patients who had previously undergone MRI scans. The training-internal validation cohort included 219 knees from Center 1. The external validation cohort comprised 35 knees from Center 2. Two musculoskeletal radiology experts manually annotated the cartilage regions. A 3D Res U-net model was employed for segmentation, and its performance was compared with 3D U-net and 3D V-net models. Segmentation results were evaluated using the Dice coefficient and Jaccard index. RESULTS:The 3D Res U-net model demonstrated superior segmentation performance compared to the other deep learning methods. For cartilage in the lateral femorotibial joint, medial femorotibial joint, and patellofemoral joint, the average Dice coefficients with 3D Res U-net were 0.871, 0.860, and 0.858 in internal validation and 0.846, 0.837, and 0.819 in external validation, respectively. The Jaccard index followed a similar trend. CONCLUSION:The 3D Res U-net model improves knee cartilage segmentation in conventional MR imaging, contributing to the understanding of cartilage morphology and the improvement of clinically relevant decisions.

To establish a radiomics-based automatic grading model for knee osteoarthritis (OA) and evaluate the influence of different body positions on the model’s effectiveness. Plain radiographs of a total of 473 pairs of knee joints from 473 patients (May 2020 to July 2021) were retrospectively analyzed. Each knee joint included anteroposterior (AP) and lateral (LAT) images which were randomly assigned to the training cohort and the testing cohort at a ratio of 7:3. First, an assessment of knee OA severity was done by two independent radiologists with Kallgren–Lawrence grading scale. Then, another two radiologists independently delineated the region of interest for radiomic feature extraction and selection. The radiomic classification features were dimensionally reduced and a machine model was conducted using logistic regression (LR). Finally, the classification efficiency of the model was evaluated using receiver operating characteristic curves and the area under the curve (AUC). The AUC (macro/micro) of the model using a combination of AP and LAT (AP LAT) images were 0.772/0.778, 0.818/0.799, and 0.864/0.879, respectively. The radiomic features from the combined images achieved better classification performance than the individual position image (p < 0.05). The overall accuracy of the radiomic model with AP LAT images was 0.727 compared to 0.712 and 0.417 for radiologists with 4 years and 2 years of musculoskeletal diagnostic experience. A radiomic model constructed by combining the AP LAT images of the knee joint can better grade knee OA and assist clinicians in accurate diagnosis and treatment. A radiomic model based on plain radiographs accurately grades knee OA severity. By utilizing the LR classifier and combining AP LAT images, it improves accuracy and consistency in grading, aiding clinical decision-making, and treatment planning.

To investigate the value of synthetic MRI sequences for quantitative detection of the muscles around the knee joints before and after a marathon. Marathon runners were examined with Synthetic MRI sequences of both knees. Quantitative profiles of T1, T2, and PD were obtained after scanning. The differences in T1, T2, and PD values of each muscle were analyzed. Most muscle subregions had elevated T1, T2, and PD values 48 hours after the marathon compared to pre-race, and decreased after 1 month of post-race rest. The synthetic MRI sequences can be useful for detecting dynamic changes in the knee muscles.

Knee osteoarthritis (OA) is the most prevalent degenerative joint disease. When morphological changes become apparent on radiographs, no approved treatment can reverse the disease process. Early diagnosis is an unmet need demanding new molecular and imaging biomarkers to define OA from the earliest stages. In this context, we focus on collagen, the most basic building block of all joint tissues, and interrogate how OA development affects collagen's molecular folding, a previously underexplored area. Here, through whole-joint mapping with a peptide that recognizes unfolded collagen molecules, we report the discovery of collagen denaturation in cartilage before proteolysis and major histopathological degeneration in animal models and patients. Mechanistically, we reveal that such molecular collagen defects can be driven by mechanical overloading without collagenase degradation and are intimately associated with glycosaminoglycan loss. We showcase the advantages of using collagen denaturation as an early-stage OA hallmark for in vivo therapeutic evaluation and molecular magnetic resonance imaging (MRI) of subtle joint defects that are challenging to detect with conventional morphology-based MRI. These results highlight biomolecular integrity as a crucial dimension for characterizing joint degeneration and a molecular foundation for diagnosing early-stage OA and beyond.### Competing Interest StatementThe authors have declared no competing interest.### Funding StatementThis work was supported by the National Natural Science Foundation of China (92059104, 82071977, 82325035, 82172481, 32271409), the 2018 High-level Health Team of Zhuhai, the Six Talent Peaks Project of Jiangsu Province (WSW-079), the Innovation Project of National Orthopedics and Sports Medicine Rehabilitation Clinical Medical Research Center (2021-NCRC-CXJJ-ZH-16), and the Guangdong-Hong Kong-Macao University Joint Laboratory of Interventional Medicine Foundation of Guangdong Province (2023LSYS001).### Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:The Ethics Committee of Nanjing Drum Tower Hospital of Nanjing University approved these studies (approval no. K228-1).I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.YesAll data produced in the present study are available upon reasonable request to the authors.

Achilles tendinopathy is often attributed to overuse, but its pathophysiology remains poorly understood. Disruption to the molecular structure of collagen is fundamental for the onset and progression of tendinopathy but has mostly been investigated in vitro. Here, we interrogated the in vivo molecular structure changes of collagen in rat Achilles tendons following treadmill running. Unexpectedly, the tendons’ collagen molecules were not mechanically unfolded by running but denatured through proteolysis during physiological post-run remodeling. We further revealed that running induces inflammatory gene expressions in Achilles tendons and that long-term running causes prolonged, elevated collagen degradation, leading to the accumulation of denatured collagen and tendinopathy development. For applications, we demonstrated magnetic resonance imaging of collagenase-induced Achilles tendon injury in vivo using a denatured collagen targeting contrast agent. Our findings may help close the knowledge gaps in the mechanobiology and pathogenesis of Achilles tendinopathy and initiate new strategies for its imaging-based diagnosis.

To assess the detection of changes in the knee cartilage of amateur marathon runners before and after long-distance running. We recruited 23 amateur marathon runners prospectively. MRI scans using UTE-MT and UTE-T2* sequences. UTE-MTR and UTE-T2* were measured for knee cartilage. The UTE-MTR values in lateral tibial plateau, central medial femoral condyle, and medial tibial plateau showed a significant decrease at 2 days post-race compared to the other two time points (P < 0.05). But no significant UTE-T2* changes were found for any cartilage subregions. UTE-MTR is a promising method for the detection of dynamic changes in knee cartilage.

Background:Knee osteoarthritis (OA) is harmful to people's health. Effective treatment depends on accurate diagnosis and grading. This study aimed to assess the performance of a deep learning (DL) algorithm based on plain radiographs in detecting knee OA and to investigate the effect of multiview images and prior knowledge on diagnostic performance.Methods:In total, 4,200 paired knee joint X-ray images from 1,846 patients (July 2017 to July 2020) were retrospectively analyzed. Kellgren-Lawrence (K-L) grading was used as the gold standard for knee OA evaluation by expert radiologists. The DL method was used to analyze the performance of anteroposterior and lateral plain radiographs combined with prior zonal segmentation to diagnose knee OA. Four groups of DL models were established according to whether they adopted multiview images and automatic zonal segmentation as the DL prior knowledge. Receiver operating curve analysis was used to assess the diagnostic performance of 4 different DL models.Results:The DL model with multiview images and prior knowledge obtained the best classification performance among the 4 DL models in the testing cohort, with a microaverage area under the receiver operating curve (AUC) and macroaverage AUC of 0.96 and 0.95, respectively. The overall accuracy of the DL model with multiview images and prior knowledge was 0.96 compared to 0.86 for an experienced radiologist. The combined use of anteroposterior and lateral images and prior zonal segmentation affected diagnostic performance.Conclusions:The DL model accurately detected and classified the K-L grading of knee OA. Additionally, multiview X-ray images and prior knowledge improved classification efficacy.

Long-distance running is a common cause of Achilles tendinopathy. A fast, reliable, and non-invasive magnetic resonance imaging (MRI) technique to track the early changes in tendon is of critical importance for effective clinical intervention and evaluation that can prevent the progression of Achilles tendinopathy. This study aims to evaluate UTE-T2* in the detection of changes in the Achilles tendons of amateur marathon runners before and after long-distance running.

Background: Knee osteoarthritis (KOA) is a common disease in the elderly. An effective method for accurate diagnosis could affect the management and prognosis of patients. Objectives: To develop a nomogram model based on X-ray imaging data and age, and to evaluate its effectiveness in the diagnosis of KOA. Methods: A total of 4403 knee X-rays from 1174 patients (July 2017 to November 2018) were retrospectively analyzed. Radiomics features were extracted and selected from the X-ray image data to quantify the phenotypic characteristics of the lesion region. Feature selection was performed in three steps to enable the derivation of robust and effective radiomics signatures. Then, logistic regression (LR), support vector machine (SVM) Ada-Boost, gradient boosting decision tree (GBDT), and multi-layer perceptron (MLP) was adopted to verify the performance of radiomics signatures. In addition, a nomogram model combining age with radiomics signatures was constructed. At last, receiver operating characteristic (ROC) curve, calibration and decision curves were used to evaluate the discriminative performance. Results: The LR model has the best classification performance among the four radiomics models in testing cohort (LR AUC vs. SVM AUC: 0.843 vs. 0.818, DeLong test P = 0.0024; LR AUC vs. GBDT AUC: 0.843 vs. 0.821, P = 0.0028; LR AUC vs. MLP AUC: 0.843 vs. 0.822, P = 0.0019). The nomogram model achieved better predictive efficacy than the radiomics model in testing cohort compared to radiomics models although the statistical dif-ference was not significant (Nomogram AUC vs. Radiomics AUC: 0.847 vs. 0.843, P = 0.06). The decision curve analysis revealed that the constructed nomogram had clinical usefulness. Conclusion: The nomogram model combining radiomics signatures with age has good performance for the ac-curate diagnosis of KOA and may help to improve clinical decision-making.

Objective:To explore the value of ultra-short echo time magnetization transfer (UTE-MT) techniques for quantitatively dynamic monitoring of anterior patellar tendon (patellar tendon, quadriceps tendon) changes in amateur marathon runners before and after competition.Methods:Between October 2020 and January 2021, 23 amateur marathoners in Zhuhai, aged 28-50 (40±6) years, were prospectively recruited. Three-dimensional UTE-MT and dual-echo UTE-T 2* sequence scans of bilateral knee joints were performed before, 48 hours and 4 weeks after the marathon running, respectively. Another 5 non-running volunteers were recruited for verification of sequence stability. UTE-magnetization transfer ratio (MTR) and UTE-T 2* value of the patellar tendon, quadriceps tendon, and 3 tendon-bone insertion points (patellar tendon-tibial insertion point, patellar tendon-patellar insertion point, and quadriceps tendon-patellar insertion point) were measured independently on sagittal images of the knee joint by 2 radiologists. The stability of the 2 serial measurements and consistency tests between the 2 radiologists were assessed with a two-way mixed intraclass correlation coefficient (ICC). Repeated-measures analysis of variance was used to compare the differences in UTE-MTR and UTE-T 2* values of the prepatellar tendon before and after the marathon running. Results:Both UTE-MT and dual-echo UTE-T 2* sequence measurements had good stability, with ICC values of 0.98 and 0.92, respectively. Measurements of UTE-MTR and UTE-T 2* value of the patellar tendon, quadriceps tendon, and the 3 tendon-bone insertion points by the 2 radiologists were in good agreement (ICC>0.80). Forty-eight hours after the marathon running, the UTE-MTR of the patellar tendon, quadriceps tendon, and the 3 tendon-bone insertion points decreased, and UTE-MTR of the patellar tendon continued to decrease 4 weeks after the race, while UTE-MTR of other regions increased. Only the difference in UTE-MTR for the patellar tendon was statistically significant ( F=7.46, P=0.001) among pre-marathon (0.34±0.04), 48 h after the race (0.32±0.04), and 4 weeks after the race (0.31±0.04). UTE-T 2* value was mildly elevated in all regions at 48 h after the marathon running, but the differences among the three points were not statistically significant ( P>0.05). Conclusion:The UTE-MT has better reproducibility and inter-rater reliability. The UTE-MT can be used to monitor the dynamic changes of the prepatellar tendon before and after marathon exercise, where the UTE-MTR of the patellar tendon consistently decreases after marathon exercise.

本文报道1例睾丸炎性肌纤维母细胞瘤。患者男，61岁，盆腔MRI示左侧睾丸上份类圆形软组织肿块，边界清晰，T 1WI呈等信号，脂肪抑制T 2WI呈混杂稍高信号，内见条片状低信号及散在小囊状高信号，周围可见低信号包膜。扩散加权成像示病灶扩散轻度受限，增强后实性部分呈延迟强化。病理诊断：左侧睾丸炎性肌纤维母细胞肿瘤。

Background Long-distance running is a common cause of Achilles tendinopathy. A reliable magnetic resonance imaging (MRI) technique to track early changes in the tendon caused by running could facilitate more effective interventions to combat progression. Purpose To evaluate an ultrashort echo time sequence with magnetization transfer preparation (UTE-MT) in the detection of changes in Achilles tendons of amateur marathon runners before and after long-distance running. Study Type Prospective. Population Thirty-two runners (19 enrolled for full marathons and 13 enrolled for half-marathons) and 5 healthy non-runners. Field Strength/Sequence 3.0 T; UTE-MT and dual-echo UTE for T2* assessment (UTE-T2*). Assessment MRI was performed 1-week pre-race, 2-days post-race, and 4-weeks post-race. UTE-MT ratio (UTE-MTR) and UTE-T2* of tendon were measured by two independent radiologists who were blinded to the scan time point and participant data. The Achilles tendon was divided into six regions of interest (ROIs) for data analysis, namely the insertion part (INS), middle part (MID), muscle-tendon junction (MTJ), tendon-bone insertion (TBI), tendon-muscle insertion (TMI), and whole tendon (bulk). Statistical Tests Analysis of variance and Friedman's rank tests were used to evaluate changes in UTE-MTR and UTE-T2* between time points. Tukey test and Bonferroni method were used for further comparisons. P < 0.05 was considered significant. Results The UTE-MTR values of most tendon ROIs changed significantly between the measured time points, except for the INS region (P = 0.1977). Conversely, the UTE-T2* values only showed significant changes in the MID and TBI regions. Paired comparisons showed that the UTE-MTR decreases in the MTJ, MID, TMI, and bulk regions at 2-days post-race were significant compared to measures taken pre-race and 4-weeks post-race. For UTE-T2* measurements, significant differences were observed only for the MID region between pre-race and 2-days post-race (P = 0.0408, 95% CI: 0.0061, 0.1973), and for the TBI region between pre-race and 4-weeks post-race (P = 0.0473, 95% CI: 0.0013, 0.1766). Data Conclusion The UTE-MT sequence is able to detect biochemical changes in the Achilles tendon after long-distance running. Level of Evidence 2 Technical Efficacy Stage 1

Objective: To explore the value of ultra-short echo time (UTE)-T2* component analysis techniques in dynamic monitoring the morphological and biochemical changes in amateur marathon athletes' achilles tendon before and after the marathon. Methods: Twenty-nine amateur marathon runners were recruited between October 2020 and March 2021 in Zhuhai City, Guangdong Province, including 25 males and 4 females, aged from 24 to 50 (40±6) years old. All volunteers underwent bilateral achilles tendon MRI examination 1 week before the marathon, 48 hours after the race, and 1 month after the race. The shape and signal of the achilles tendon were evaluated by routine T1-weighted, proton density weighted with fat saturation sequence and different echo time (TE) UTE sequence, and the changes of achilles tendon after running was quantitatively analyzed by UTE-T2* sequence. The values of single-component analysis (T2*M), short T2* components (T2*S), and long T2* components (T2*L) and Fraction values were obtained using UTE-T2* sequence. The value of the whole achilles tendon was measured on the sagittal images of achilles tendon, and the Achilles tendon was equally divided into three subregions [muscle-tendon junction (MTJ), middle (MID), and insertion (INS)]. The region of interest was delineated by two radiologists independently. The intra-group correlation coefficient (ICC) was used to evaluate the consistency of the data measured by two radiologists. Nonparametric Friedman M test was used to compare the differences of T2*M, T2*S, T2*L and Fraction values in different time points and different subregions. Wilcoxon rank-sum test was used to compare the difference between 48 h post-race and pre-race T2*S values (ΔT2*S) of different distance, different running posture, different pace and different amount of training, in which ΔT2*S equals the T2*S value of 48 h post-race minus the T2*S value of pre-race. Results: On the sequence of short TE (TE≤0.6 ms), achilles tendinopathy can manifest as scattered punctate hypointensity in areas of high signal intensity. The two radiologists showed a good consistency in measuring the T2*M, T2*S, T2*L and Fraction values of the achilles tendon, and the ICC values ​​were 0.96, 0.94, 0.83 and 0.94, respectively. The T2*s values was significantly higher in the whole Achilles tendon, MTJ and MID segment at 48 h post-exercise compared to pre-exercise, and decreased after 1 month of exercise, [0.49 (0.45, 0.59) vs 0.54 (0.49, 0.59) vs 0.53 (0.49, 0.57), 0.48 (0.44, 0.54) vs 0.53 (0.47, 0.58) vs 0.50 (0.46, 0.57), 0.48 (0.43, 0.58) vs 0.54 (0.47, 0.59) vs 0.52 (0.46, 0.57); respectively, all P<0.05]. The changes in T2*M, T2*L and Fraction values are not statistically significant (all P>0.05). In different running gestures, the ΔT2*S of achilles tendon who using the postures of front-middle feet is higher than that using the postures of back feet (0.03(-0.05, 0.07) vs -0.03(-0.17, 0.11), P=0.001). Conclusion: The Bi-component analysis of UTE-T2* technology is superior to single component analysis in monitoring the dynamic changes of achilles tendon before and after exercise, and T2*S is a more sensitive sequence to evaluate the subtle changes in the chemical composition of achilles tendon.

肌腱、韧带及其附着点的病变与很多骨肌系统的炎性和退行性疾病密切相关。MRI因具有良好的组织分辨率，在骨肌软组织病变的诊断中具有较大优势，但正常肌腱和附着点的横向弛豫时间（T 2）较短，目前常规MRI序列几乎没有信号，这为肌腱及附着点的MRI特性的研究带来了极大的困难。该研究使用新型3.0 T 磁共振三维超短回波时间（3D UTE）序列和11.7 T常规MRI序列对正常肌腱和附着点结构显示。在这项研究中，使用3.0 T磁共振的3D UTE序列对5个踝关节标本［男2例，女3例，平均年龄（35.4±5.0）岁］进行扫描，研究跟腱和附着点的T 2*、T 1和磁化转移率（MTR）的MRI特性，并进行大分子质子组分MT建模。同时，使用11.7 T常规MRI序列对其进行形态学观察，通过压痕测试来研究跟腱和附着点的力学特性，并通过病理切片进行组织学分析。跟腱和附着点的T 2*值分别为（0.93±0.48）ms和（2.77±0.79）ms，T 1值分别为（644±22）ms和（780±55）ms，MTR分别为0.373±0.030和0.244±0.009，平均功率为1 000°，频率偏移为2 kHz，大分子质子分数分别为（18.0±2.2）%和（13.9±1.9）%。与跟腱相比，附着点通常有更长的T 2*和T 1值，更低的MTR和大分子质子分数，以及更高的杨氏模量和刚度。这项研究为正常人跟腱及附着点提供了基线值，可用于血清阴性关节炎和其他末端疾病的诊断。

Objective:To explore the value of synthetic MRI in quantitative monitoring of knee joint structural and cartilage changes of amateur marathon runners before and after the whole marathon.Methods:Totally 26 amateur marathon enthusiasts from Zhuhai City, Guangdong Province were recruited from October 2019 to January 2020. The right knee joints were scanned 1 week before the race and within 48 h after the race. The scanning sequence included the three-dimensional proton density weighted image with isotropic (3D-CUBE-PD) sequence and synthetic MRI sequence. The conventional contrast weighted images T 1WI, T 2WI, proton density (PD) weighted imaging, short-T 1 inversion recovery (STIR) and T 1, T 2, PD mapping were obtained by the latter scans. The 3D-CUBE-PD sequence was used as a reference to evaluate the detection of knee joint lesions. The knee articular cartilage was divided into 8 subregions: central medial femoral condyle (CMFC), posterior medial femoral condyle (PMFC), central lateral femoral condyle (CLFC), posterior lateral femoral condyle (PLFC), medial tibia plateau (MTP), lateral tibia plateau (LTP), patella and trochlear. Based on the synthetic MRI quantitative mapping, the T 1, T 2 and PD values of each cartilage subregion were measured independently by 2 radiologists. The ICC was used to evaluate the consistency of the measurement between observers. The T 1, T 2 and PD values of knee cartilage before and after marathon exercise were compared by Wilcoxon signed rank test. Results:The 2 radiologists had good consistency in the measurement of T 1, T 2 and PD values of knee articular cartilage with the ICC values of 0.912, 0.933 and 0.954, respectively. The synthetic MRI quantitative mapping sequence can detect all cartilage damage ( n=3) and joint effusion ( n=15), and 7 of 9 meniscus injuries were detected. The T 1, T 2 and PD values of the knee cartilage as a whole before the race were higher than those after race, and the differences were statistically significant (all P<0.05). The T 1 values were statistically significant except patellar cartilage and trochlear cartilage, and T 2 values were significantly different in the CMFC, LTP, MTP ( P<0.05). Conclusion:Synthetic MRI has a good display of knee joint structural lesions, and its quantitative parameters T 1, T 2 and PD can detect the changes of knee cartilage before and after marathon.

目的 探讨集成磁共振(synthetic magnetic resonance imaging,SyMRI)技术在正常成年人海马定量测量中的应用价值.材料与方法 连续收集20～72岁健康成年人139名,男性61名,女性78名.按照年龄分为三组:20～35岁36名,36～55岁72名,56～72岁31名.所有受试者均采用GE SIGNA Pioneer 3.0 T MRI进行头颅检查.扫描序列包括3D T1WI毁损梯度回波序列(3D T1WI spoiled gradient recalled echo,3D T1WI-SPGR)和SyMRI序列,应用SyMRI后处理软件对全脑进行自动配准及数值提取.不同侧别间的海马T1、T2及质子密度(proton density,PD)值采用配对t检验,不同性别分组间的海马T1、T2及PD值采用两独立样本Mann-Whitney U检验,不同年龄组间采用方差分析,不同年龄分组内两两比较采用LSD法.结果 139名健康成年人的T1、T2、PD均值分别分别是(1258.43±110.59)ms、(105.88±16.05)ms、(74.71±1.52)pu,T1值、T2值、PD值的范围依次是(1070.16～1725.59)ms、(86.43～190.71)ms、(70.72～80.21)pu.不同侧别海马T1和PD值差异均有统计学意义(P值均<0.05),且T1和PD值左侧均大于右侧.而不同侧别海马T2值以及不同性别间的T1、T2和PD值之间没有统计学差异(P>0.05).T1、T2及PD值不同年龄组之间差别有统计学意义(P<0.05),20～35岁组和36～55岁组与56～72岁组之间差异有统计学意义(P<0.05),20～35岁组与36～55岁组之间差异无统计学意义(P>0.05).结论 集成磁共振技术能够提供不同年龄及性别正常成年人海马定量参考值,为海马相关疾病的早期诊断提供重要依据.

Long-distance running is one of the common causes of Achilles tendon injury. UTE-MT is a magic angle-insensitive MRI technique and an excellent fit for the assessment of Achilles tendon which has a highly anisotropic collagen structure.This study aims to explore the feasibility of quantitative UTE-MT imaging in the assessment of Achilles tendon changes for subjects before and after long-distance running, then compare the technique’s performance with that of UTE-T2*.