Objective:To evaluate the application high-resolution 3.0-T magnetic resonance imaging (MRI) in diagnosis of ligament and tendon injuries of the forefeet.Methods:From September 2014 to August 2020, 40 patients with forefeet injury (40 forefoot) and 20 healthy subjects (40 forefoot) meeting the including and excluding criteria were enrolled into this retrospective study. All subjects underwent MRI T1-weighted image (T1WI) and fat suppression proton density-weighted imaging (PD-FS) scan on coronal planes, sagittal planes and axial planes, respectively. Then the MRI characteristics of tendons in forefoot of healthy subjects and patients with forefoot injuries were compared. In patients the MR features of ligament and tendons injury were compared with the surgical findings or follow-up results.Results:In 20 normal subjects the tendons and ligament of the forefoot showed homogeneous low-signal-intensity on T1WI and PD-FS images. In the 40 patients with forefoot injuries, 22 cases were confirmed by surgical findings and 18 cases were confirmed by follow-up results. There were 8 cases of collateral ligament injuries, including 2 cases with complete tear, 3 cases with partial tear and 3 cases with sprain; 2 cases of extensor tendon with partial tear; 8 cases of flexor tendon injuries, including 3 cases with complete tear, 3 cases with partial tear and 2 cases with sprain; 3 cases of abductor tendon with partial tear; 13 cases of plantar plate injuries; and 6 cases of Lisfranc ligament injuries including 5 cases with complete tear and 1 case with partial tear. The injured ligament and tendons presented thicker and discontinuity in T1WI; and demonstrated heterogeneously increased signal intensity with edema in the surrounding soft tissues in PD-FS. The partially torn ligament and tendons showed discontinuity and thickening; and the completely torn ligament and tendons showed that they were interrupted and retracted, fiber structure disappeared and was filled with liquid, and edema in the surrounding soft tissue.Conclusion:High resolution magnetic resonance imaging of the forefoot can demonstrate the anatomy and features of ligament and tendon injuries in forefoot accurately, which has clinical application value for the early diagnosis and accurate treatment of the injury.

Objective: To study the MRI manifestations of foot injuries in amateur marathoners and the diagnostic value of MRI for foot injuries. Methods: Forty-eight amateur marathoners were prospectively recruited from October 2018 to March 2019. Participants were grouped according to the FASS criteria. All participants underwent bilateral foot MRI examinations. The MRI features of foot in amateur marathoners with and without foot pain were analyzed.The association with gender, age, time to participate in marathon, amount of running per week, number of times to complete the whole marathon and the symptoms of foot pain was studied. Results: There were 28 sides in FASS in grade 0, including 8 males and 20 females, 8 hydrocele of the first metatarsophalangeal joint, 6 edema of bone marrow, 4 edema of soft tissue, 4 hydrocele of tendon sheath, and 6 without abnormal manifestations of MRI. There were 68 sides in FASS grade 1, including 42 males and 26 females, 38 Achilles tendinitis, 14 plantar fasciitis, 12 Achilles tendon bursitis and 4 posterior ankle impingement syndrome. The incidence of foot pain in amateur marathoners was related to gender (OR=1.060, P=0.043), unrelated to age (OR=0.248, P=0.078), number of marathons completed (OR=1.006, P=0.956), time to participate in marathon (OR=1.008, P=0.944), amount of running per week (OR=0.971, P=0.407). Conclusion Among amateur marathon runners, the foot pain is mainly caused by Achilles tendon and plantar fascia, while those without foot pain are mainly characterized by joint effusion, tendon sheath effusion and bone marrow edema. Gender is the only factor affecting the incidence of foot pain in amateur marathoners. MRI examination is an effective method to determine foot injury and has important clinical application value in the diagnosis and treatment of foot injury.

Objective To study the MRI manifestations of foot injuries in amateur marathoners and the diagnostic value of MRI for foot injuries. Methods Forty?eight amateur marathoners were prospectively recruited from October 2018 to March 2019. Participants were grouped according to the FASS criteria. All participants underwent bilateral foot MRI examinations. The MRI features of foot in amateur marathoners with and without foot pain were analyzed.The association with gender, age, time to participate in marathon, amount of running per week, number of times to complete the whole marathon and the symptoms of foot pain was studied. Results There were 28 sides in FASS in grade 0, including 8 males and 20 females, 8 hydrocele of the first metatarsophalangeal joint, 6 edema of bone marrow, 4 edema of soft tissue, 4 hydrocele of tendon sheath, and 6 without abnormal manifestations of MRI. There were 68 sides in FASS grade 1, including 42 males and 26 females, 38 Achilles tendinitis, 14 plantar fasciitis, 12 Achilles tendon bursitis and 4 posterior ankle impingement syndrome. The incidence of foot pain in amateur marathoners was related to gender(OR=1.060, P=0.043), unrelated to age(OR=0.248, P=0.078), number of marathons completed(OR=1.006, P=0.956), time to participate in marathon(OR=1.008,P=0.944), amount of running per week (OR=0.971,P=0.407). Conclusion Among amateur marathon runners, the foot pain is mainly caused by Achilles tendon and plantar fascia, while those without foot pain are mainly characterized by joint effusion, tendon sheath effusion and bone marrow edema. Gender is the only factor affecting the incidence of foot pain in amateur marathoners. MRI examination is an effective method to determine foot injury and has important clinical application value in the diagnosis and treatment of foot injury.

Objective:To study the relationship between distal radioulnar joint (DRUJ) effusion and the integrity of triangular fibrcarotilage (TFC) in asymptomatic young adults.Methods:Thirty two asymptomatic young adults, 22 males and 10 females with a mean age of 25 year(20-30) were recruited in the study between September 2014 and October 2019. All subjects had no wrist pain, no wrist deformity or wrist mass, and had no history of wrist trauma or surgery. The DRUJ effusion was definedasfluid-like high signal intensityon fatsuppression proton density-weighted MRI.The presence of distal radioulnar joint effusion, the shape of the effusion, and the presence of triangular fibrocartilage abnormalities were documented.Results:Among 32 subjects, 25(78.1%, 15 males and 10 females) presented with distal radioulnar joint effusion on wrist MR images, including linear/tubular in 21 cases(84.0%) and saccular in 4 cases(16.0%).Twenty cases (62.5%) had distal radioulnar joint effusion while the TFC was intact, among whom, the effusion was confined to the proximal side of distal radioulnar jointin 17 cases, and reached the lower surface of TFC in 3 cases. In 5 cases (15.6%) with TFC tear, the effusion reached the lower surface of TFC in 4 cases. There were neutral, positive and negative variations of the ulna in 23, 6 and 3 cases, respectively, among whomthe distal radioulnar effusion was presented in 17, 5, 3 cases, and TFC tear in 1, 4 and 0 cases, respectively.The presence of distal radioulnar effusion was not significantly correlated with genders( P=0.069) or types of ulna variance( P=0.702). Conclusion:The distal radioulnar joint effusion maybe resent in asymptomatic young adults, and it maybe complicated with TFC tear.

Objective:To explore the anatomy and injuries features of the thumb extensor and flexor mechanism with MRI.Methods:Ten healthy subjects without thumb injury and 20 patients with thumb extensor or flexor mechanism injuries were recruited in the study between September 2013 and September 2021. All subjects underwent MRI examination, the MRI features of thumb extensor or flexor mechanism in healthy subjects and patients were analyzed. The imaging findings were compared with the surgical results and confirmed by followed up in patients.Results:The healthy subjects showed homogeneous low-signal-intensity on T1-weighted and proton-fat saturation sequence(PD FS) images. Twenty patients with thumb extensor or flexor mechanism injures(including 8 cases of extensor pollicislongusinjury,1 case of extensor pollicisbrevis injury, 4 cases of flexor pollicislongus injury, 2 cases offlexor pollicis brevis injury and 5casesofpulley injury) demonstrated poor definition in T1WI, and heterogeneously increased signal intensity in PD-FS. Depending on the degree of injury, the fibers may be partially or completely discontinuity of the involved tendons. There was edema in the soft tissues surrounding the injured sites.Conclusion:MRI is an accurate method for evaluation of the anatomy and pathological conditions of the thumb extensor and flexor mechanism.

Objective To explore the MRI characteristics of anatomy and injuries of the tendons and ligaments in the midfoot.Methods Twenty healthy volunteers and 46 patients with midfoot trauma were selected for retrospective analysis.All subjects underwent examination on MR T1WI and proton density-fat suppression(PD FS)scans on three planes,respectively.Then the MRI features of tendon and ligaments injury were compared.Results The tendons and ligaments of 20 healthy volunteers(40 lateral feet)showed homogeneous low signal intensity with varing thickness.The anterior tibialis tendons showed a thin linear shape,and the posterior tibialis tendons showed a slightly thick band with uniform low signal intensity,and the calcaneonavicular ligament showed thin linelike low signal in different directions.In the 46 patients with midfoot injuries,there were 16 cases of anterior tibialis tendons injuries,18 cases of posterior tibialis tendons injuries,and 12 cases of calcaneonavicular ligament injuries.According to the MRI findings,the degree of injuries of tendons and ligaments was divided into injury,partial tear,and complete rupture.Conclusion MRI can clearly show the anatomy and injury features of ligaments and tendons in midfoot,which is of important value for the early diagnosis and accurate treatment of the ligaments and tendons injuries.

Objective:To explore the magnetic resonance imaging (MRI)features of the normal anatomy and injuries of ligaments in the elbow joint.Methods:Thirty-eight healthy volunteers (38 sides) and 82 patients with elbow joint injuries were recruited in the Radiology Department of Beijing Jishuitan Hospital from February 2019 to February 2022 and the MRI findings were analyzed. The healthy subjects had no history of trauma, elbow joint ligament injury or pain, and the elbow joint function was normal. Among the 82 patients with elbow joint injuries, 8 cases were confirmed by operation and 74 were confirmed by follow-up. The MRI characteristics of normal anatomy and injuries of the medial collateral ligament and lateral collateral ligament complex of the elbow were compared and analyzed by blind method.Results:The medial collateral ligament and lateral collateral ligament complex in 38 healthy volunteers showed as thin strip low signal on T1-weighted imaging (T1WI) and fat suppression proton density-weighted imaging (PD-FS), and the annular ligament showed as annular linear low signal surrounding the radial head. Among the 82 patients with elbow injuries, in the medial side, there were 6 cases with medial collateral ligament injuries alone, 2 with common flexor tendon injuries alone, and 4 with medial collateral ligament and common flexor tendon injuries; while in the lateral side, there were 9 cases with the lateral collateral ligament complex injuries alone, 21 with common extensor tendon injuries alone, and 31 with the lateral collateral ligament complex and common extensor tendon injuries. In addition, there were 9 cases of medial collateral ligament coupled with lateral collateral ligament complex injuries. Among the 9 cases of combined ligament injuries (5 cases with injuries of the common flexor or extensor tendon), 5 cases were complete tears and 4 cases were partial tears. Among the 10 cases of medial collateral ligament injuries, 9 patients were strain and one was complete tear. Among the 40 cases of lateral collateral ligament complex injuries, 29 patients were strain, 10 were partial tears and one was complete tear. The strained ligament showed as thickened and blurred on T1WI, and the fiber was still continuous; while on PD-FS, the injured ligaments demonstrated as heterogeneously increased signal intensity. Partial tear showed as fiber thickening and partial discontinuity. A complete tear showed that the fiber was discontinuous and retracted with surrounding soft tissue edema.Conclusion:MRI is an accurate method for evaluation of the anatomy and pathological conditions of the medial collateral ligament and lateral collateral ligament complex of the elbow joint, and has important application value in the diagnosis and treatment of elbow ligament injury.

Objective:To explore the optimal keV value of the virtual monoenergetic image (VMI) for displaying the osteosarcoma by using the dual-layer spectral detector CT and to evaluate its application value in determining the extent of intramedullary invasion of osteosarcoma.Methods:From August 2021 to August 2022, 57 patients with conventional osteosarcoma of long bone confirmed by biopsy in Beijing Jishuitan Hospital, Capital Medical University were retrospectively analyzed. All patients completed dual-layer spectral CT enhanced examination before limb salvage surgery, and tumor segment resection specimens were obtained after surgery. Conventional 120 kVp image and VMI of 40, 50, 60, 70 and 80 keV were obtained by spectral CT examination, and the CT values of tumors, image noise were measured and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the corresponding images were calculated. The objective evaluation among the six groups of images were assessed with the Friedman test, and then determined the optimal keV value. The maximum distance between the intramedullary boundary of osteosarcoma and the adjacent articular surfaces was measured on the best keV VMI and the tumor segment resection specimens. The Wilcoxon signed rank test was used to find the differences and the Spearman correlation analysis was used to evaluate the correlation between the distance measured from the best keV VMI and the specimens.Results:There were significant differences in CT value, image noise, SNR and CNR between 40-80 keV VMI and 120 kVp conventional CT images ( P<0.05). The CT value, SNR and CNR of 40 and 50 keV VMI were better than 120 kVp ( P<0.001). The 50 keV VMI was chosen as the best keV VMI to measure the intramedullary extent of osteosarcoma. The distance measured from 50 keV VMI was 103.9 (80.4, 131.4) mm, while the distance measured from specimens was 113.5 (94.0, 142.0) mm, and the difference was statistically significant ( Z=-5.76, P<0.001). The 50 keV VMI measurements in 51 patients were smaller than the gross specimens, which underestimated the tumor intramedullary extent, with the difference was 11.1 (6.6, 13.8) mm. The Spearman correlation analysis demonstrated a high positive correlation of distance measured on gross specimens with the 50 keV VMI ( r s=0.960, P<0.001). Conclusions:Dual-layer spectral detector CT with 50 keV VMI is the best image to show the limb osteosarcoma. Compared with gross specimens, the distance measured from CT underestimated the intramedullary invasion range of limb osteosarcoma about 10 mm, but the two show a good correlation.

Objective:To explore the feasibility of MRI to assist the early diagnosis of midfoot tendon and ligament injuries.Methods:Fifty-two patients with midfoot ligament and tendon injuries who visited Beijing Jishuitan Hospital from September 2016 to December 2021 were enrolled in the study, and 20 healthy volunteers were recruited as controls. All participants underwent mid foot coronal (short axis), sagittal, and axial (long axis) MRI T1 weighted imaging and proton fat suppression sequence examination. The MRI images were evaluated by 2 senior radiologists independently.Results:The consistency of the two radiologists in diagnosis of tendons, ligaments, bones, and soft tissues were good ( κ=0.916, 0.896, and 0.893, respectively). The tendons and ligaments of the midfoot in 20 healthy volunteers (40 feet) showed uniform bands of varying thickness with slightly low signal intensity; the anterior tibial tendon showed a thin line shape, the posterior tibial tendon showed a slightly thick band with uniform low signal intensity, and the calcaneonavicular ligament showed a thin line-like low signal intensity running in different directions. In 52 patients with midfoot tendon and ligament injuries, 18 had anterior tibial tendon injuries, 20 had posterior tibial tendon injuries, and 14 had calcaneonavicular ligament injuries. The injured tendon or ligament was characterized by uneven thickness, blurred edges, and continuous interruption on T1WI sequence, uneven enhancement of signal in the tendon or ligament running area on PD-FS sequence, accumulation of fluid in the tendon sheath, and partial tearing. The partial tear showed discontinuity and thickening of tendons, while the complete tear showed that the tendons were interrupted and retracted, the fiber structure disappeared and was filled with liquid, and the surrounding soft tissue edema was present. Conclusion:MRI can clearly display the course and anatomical structure of the attachment end of the midfoot tendon and ligament, which may assist in early diagnosis of midfoot tendon and ligament injuries.

Objective:To analyze the MRI findings of tendinopathy of the common extensor tendon (CET) and common flexor tendon (CFT) and to explore its application for injury classification.Methods:Sixty-two patients with elbow tendinopathy of CET and/or CFT who were examined in the Radiology Department of Beijing Jishuitan Hospital from August 2019 to April 2022 were enrolled as the case group, and 20 healthy subjects (40 elbows) were recruited as the control group. The clinical data of patients and MRI findings of elbow joint of all subjects were reviewed. The MRI of tendinopathy of CFT and CET were read by 2 senior radiologists independently, and the consistency was tested by the κ test. The MRI manifestations for injury classification were discussed. Results:The κ values of CFT, CET, medial collateral ligament complex and lateral collateral ligament complex were 0.645, 0.657, 0.615 and 0.653 respectively. MRI clearly showed the anatomical structure of CFT, CET and surrounding soft tissue. The CFT and CET of the elbow of 20 normal volunteers (40 sides) in the control group showed thin line or banded low signal in each MRI sequence, and the muscle fibers were continuous. In 27 patients with classification Ⅰ injury of CFT and/or CET of elbow joint, MRI showed thickening or thinning of tendons and increased signal intensity on fat suppression T2-weighted imaging. In 27 cases of classification Ⅱ injury, MRI showed that the fluid signal involved 20% to 80% of the tendon thickness. In 8 cases of classification Ⅲ injury, MRI showed that the fluid signal involved more than 80% of the tendon thickness. Conclusions:Tendinopathy of CFT and CET of elbow joint has its characteristic MRI manifestations, indicating that MRI can be used for the diagnosis of tendinopathy. In addition, MRI can also be used for the injury classification.