Prediction of anterior tibiotalar ligament injury: measurement of the angle between the deep posterior tibiotalar ligament and talus on MRI.

BACKGROUND: Identification of anterior tibiotalar ligament (aTTL) injury is essential because it influences the surgeon's treatment option and patient prognosis. PURPOSE: To assess the diagnostic accuracy of the angle measurement between the talus and posterior tibiotalar ligament (talus-pTTL) on magnetic resonance imaging (MRI) in patients with arthroscopically proven aTTL injuries. MATERIAL AND METHODS: Ankle MRI scans of 67 patients who underwent arthroscopic examination were retrospectively reviewed. The talus-pTTL angle on axial T2-weighted MRI and the medial clear space (MCS) on mortise ankle radiograph were measured. Inter-observer agreement of the measurements was calculated. Also, sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (AUC) were the metrics of diagnostic accuracy. RESULTS: AUC was 0.90 for observer 1 with 78.6% sensitivity, 97.4% specificity, 88% accuracy, and 54.7° cutoff value for the talus-pTTL angle. AUC was 0.87 for observer 2 with 85.7% sensitivity, 84.6% specificity, 85.2% accuracy, and 53.7° cutoff value for the talus-pTTL angle. AUC was 0.86 with 82.1% sensitivity, 79.5% specificity, and 80.8% accuracy for observer 1 and 0.79 with 57.1% sensitivity, 92.3% specificity, and 74.7% accuracy for observer 2 for the MCS. Different MCS values and additional capabilities when complemented with the angle measurement showed an increase in diagnostic performances. Intra-observer reliability of MCS and talus-pTTL angle of the two radiologists was excellent. Inter-observer reliability of the two radiologists was excellent for both the talus-pTTL angle (0.95) and the MCS (0.85). CONCLUSION: Measurement of the talus-pTTL angle showed good sensitivity, specificity, and accuracy for the evaluation of aTTL injury with excellent inter-observer reliability.

Comparison of shear wave elastography with gray-scale USG and CT for quantitative evaluation of rectus femoris muscle.

PURPOSE: The purpose of this study was to compare the measurement of shear wave elastography (SWE) and gray scale ultrasonography (GSU) and CT attenuation of mid-rectus femoris (RF) muscle in healthy adults. METHODS: This prospective study included 70 participants with a healthy body mass index (<25 kg/m2 ) between June 2019 and January 2020. Echo intensity (EI) grading of RF on GSU was performed. SWE was performed for the three levels of the RF. Measurements were repeated 10 min after the first measurement. The mid-RF attenuation on CT was also measured. Interobserver agreement of EI grade among three readers was assessed using weighted-kappa statistics. The reliability of SWE was assessed using intraclass correlation coefficient. The correlations between the SWE and CT/GSU measurements were analyzed. RESULTS: Interobserver agreement of EI grade on GSU by the three radiologists was moderate to substantial (k = 0.562-0.767). The inter-session agreements for SWE were almost perfect for mid RF (k = 0.822-0.829) and substantial for proximal and distal RF (k = 0.767-0.795). There were significant correlations between SWE-EI and SWE-CT attenuation (p < 0.001, respectively) at the mid-RF. CONCLUSIONS: SWE measurements on mid-RF demonstrated the highest reliability. SWE parameters showed a strong correlation with EI on GSU and attenuation on CT.

Determining the Feasibility of Arthroscopic Anterior Talofibular Ligament Repair Utilizing a Novel Classification System.

The purposes of this study were to classify anterior talofibular ligament injuries (ATFL), to find out the feasibility of arthroscopic ATFL repair according to injury type and to investigate the diagnostic validity of magnetic resonance imaging (MRI) of ATFL injuries by comparing MRI and arthroscopic findings. The 197 ankles (93 right, 104 left, and 12 bilateral) of 185 patients (90 men and 107 women; mean age, 33.5 years, range: 15-68 years) were treated by arthroscopic modified Broström procedure after a diagnosis of chronic lateral ankle instability. ATFL injuries were classified according to their grade and location (type P: partial rupture, type C1: fibular detachment, type C2: talar detachment, type C3: midsubstance rupture, type C4: absence of ATFL, type C5: os subfibulare). Among the 197 injured ankles, according to ankle arthroscopy, 67 were type P (34%), 28 were type C1 (14%), 13 were type C2 (7%), 29 were type C3 (15%), 26 were type C4 (13%), and 34 were type C5 (17%). The kappa value for the agreement between the arthroscopic findings and MRI findings was also high (0.85; 95% confidence interval, 0.79-0.91). Our results also supported the use of MRI for diagnosing ATFL injuries and showed that it is an informative tool during the preoperative period.

Can Bone Erosion in Axial Spondyloarthropathy be Detected by Ultrashort Echo Time Imaging? A Comparison With Computed Tomography in the Sacroiliac Joint.

BACKGROUND: Structural lesion evaluation in axial spondyloarthropathy (SpA) can improve accuracy of diagnosis. However, structural lesions (bone erosions) are difficult to be assessed using conventional MRI compared to computed tomography (CT). PURPOSE: To evaluate the diagnostic performance of ultrashort echo time (UTE) for detecting bone erosion in axial SpA compared to T1WI and three-dimensional double-echo steady-state (3D DESS) imaging using CT as the reference standard. STUDY TYPE: Retrospective. POPULATION: Fourteen patients (eight females, 57.1%) and 14 healthy controls (seven females, 50.0%) who underwent sacroiliac (SI) joint MRI and CT. FIELD STRENGTH/SEQUENCE: 3 T; TSE T1WI, 3D DESS, 2D UTE. ASSESSMENT: The bilateral SI joints were assessed for bone erosion. Three observers scored bone erosion for all three sequences of MRI. CT was used as the gold standard. Diagnostic confidence in axial SpA was measured based on a four-point confidence score. STATISTICAL TESTS: Correlation of erosion scores between CT and MRI were evaluated using Spearman's correlation test. Sensitivity, specificity, and positive-negative predictive values were calculated. Confidence scores were compared using the Wilcoxon sum rank test. Statistical significance was set at P < 0.05. RESULTS: Compared with erosion scores of CT, the correlation coefficients for each MRI sequence showed significant low-to-high positive correlations (0.39-0.72). UTE imaging showed the highest correlation coefficients for all observers (0.70, 0.72, and 0.67, respectively). The specificity of UTE imaging was equal or higher than those of T1WI and 3D DESS for all observers (0.86 vs. 0.71 vs. 0.57; 0.93 vs. 0.71 vs. 0.57; 0.79 vs. 0.79 vs. 0.43). All observers had the highest confidence in interpreting UTE imaging for detecting bone erosion among the three sequences (3.5, 3.4, and 3.3 for UTE; 3.1, 3.0, and 2.6 for T1WI; and 3.2, 2.7, and 2.4 for DESS). DATA CONCLUSION: UTE imaging can detect bone erosions in patients with axial SpA and show higher specificity than conventional T1WI and 3D DESS. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 2.

Deep learning image reconstruction algorithm for abdominal multidetector CT at different tube voltages: assessment of image quality and radiation dose in a phantom study.

OBJECTIVES: To compare the image quality and radiation dose of a deep learning image reconstruction (DLIR) algorithm compared with iterative reconstruction (IR) and filtered back projection (FBP) at different tube voltages and tube currents. MATERIALS AND METHODS: A customized body phantom was scanned at different tube voltages (120, 100, and 80 kVp) with different tube currents (200, 100, and 60 mA). The CT datasets were reconstructed with FBP, hybrid IR (30% and 50%), and DLIR (low, medium, and high levels). The reference image was set as an image taken with FBP at 120 kVp/200 mA. The image noise, contrast-to-noise ratio (CNR), sharpness, artifacts, and overall image quality were assessed in each scan both qualitatively and quantitatively. The radiation dose was also evaluated with the volume CT dose index (CTDIvol) for each dose scan. RESULTS: In qualitative and quantitative analyses, compared with reference images, low-dose CT with DLIR significantly reduced the noise and artifacts and improved the overall image quality, even with decreased sharpness (p < 0.05). Despite the reduction of image sharpness, low-dose CT with DLIR could maintain the image quality comparable to routine-dose CT with FBP, especially when using the medium strength level. CONCLUSION: The new DLIR algorithm reduced noise and artifacts and improved overall image quality, compared to FBP and hybrid IR. Despite reduced image sharpness in CT images of DLIR algorithms, low-dose CT with DLIR seems to have an overall greater potential for dose optimization. KEY POINTS: • Using deep learning image reconstruction (DLIR) algorithms, image quality was maintained even with a radiation dose reduced by approximately 70%. • DLIR algorithms yielded lower image noise, higher contrast-to-noise ratios, and higher overall image quality than FBP and hybrid IR, both subjectively and objectively. • DLIR algorithms can provide a better image quality, much better than FBP and even better than hybrid IR, while facilitating a reduction in radiation dose.

Diffusion tensor imaging of the sciatic nerve in Charcot-Marie-Tooth disease type I patients: a prospective case-control study.

OBJECTIVES: This study aimed to evaluate whether diffusion tensor imaging (DTI) parameters and cross-sectional area (CSA) can differentiate between the sciatic nerve of Charcot-Marie-Tooth (CMT) disease type I (demyelinating form) patients and that of controls. METHODS: This prospective comparison study included 18 CMT type I patients and 18 age/sex-matched volunteers. Magnetic resonance imaging including DTI and axial T2-weighted Dixon sequence was performed for each subject. Region of interest analysis was independently performed by two radiologists on each side of the sciatic nerve at four levels: hamstring tendon origin (level 1), lesser trochanter of the femur (level 2), gluteus maximus tendon insertion (level 3), and mid-femur (level 4). Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were calculated. The CSA of the sciatic nerve bundle was measured using axial water-only image at each level. Comparisons of DTI parameters between the two groups were performed using the two-sample t test and Mann-Whitney U test. Interobserver agreement analysis was also conducted. RESULTS: Interobserver agreement was excellent for all DTI parameter analyses. FA was significantly lower at all four levels in CMT patients than controls. RD, MD, and CSA were significantly higher at all four levels in CMT patients. AD was significantly higher at level 2 in CMT patients. CONCLUSION: DTI assessment of the sciatic nerve is reproducible and can discriminate the demyelinating nerve pathology of CMT type I patients from normal nerves. The CSA of the sciatic nerve is also a potential parameter for diagnosing nerve abnormality in CMT type I patients. KEY POINTS: • Diffusion tensor imaging parameters of the sciatic nerve at proximal to mid-femur level revealed significant differences between the Charcot-Marie-Tooth disease patients and controls. • The cross-sectional area of the sciatic nerve was significantly larger in the Charcot-Marie-Tooth disease patients. • Interobserver agreement was excellent (intraclass coefficient > 0.8) for all diffusion tensor imaging parameter analyses.

Dual-Energy and Iterative Metal Artifact Reduction for Reducing Artifacts Due to Metallic Hardware: A Loosening Hip Phantom Study.

OBJECTIVE. The purpose of this study was to compare the value of iterative metal artifact reduction (IMAR) with that of dual-energy CT (DECT) and filtered back projection (FBP) CT protocols for reducing metal artifacts and for facilitating visualization of the acetabular cortex in a loosening hip phantom model. MATERIALS AND METHODS. CT scans were obtained with conventional FBP and dual-source CT for two types of hip phantom. For the quantitative study, attenuation was measured by placement of ROIs in the phantoms around the metallic hardware. The differences between mean attenuation in each ROI and the actual attenuation were compared among the three CT protocols. For the qualitative study, the visibility of the acetabular cortex in the artificial loosening area of the total hip arthroplasty model and in the joint space of the bipolar hemiarthroplasty model was evaluated by measurement of the obscured cortical angle. RESULTS. In the quantitative study, attenuation differences in the bipolar hemiarthroplasty model were markedly decreased with IMAR and DECT compared with FBP (p = 0.006-0.007). In the total hip replacement model, attenuation differences were significantly lower with IMAR than with FBP (p < 0.001). In the qualitative study, visibility of the acetabular cortex was markedly improved with IMAR compared with DECT and FBP (p < 0.001) for both hip models. CONCLUSION. CT with IMAR can reduce the distortion caused by metal artifacts more effectively than FBP and DECT can while preserving visibility of the acetabular cortex in both bipolar hemiarthroplasty and total hip arthroplasty phantoms.

Ultrasound-guided percutaneous bone drilling for the treatment of lateral epicondylitis.

OBJECTIVE: To determine the clinical efficacy of sonographically-guided percutaneous bone drilling of the lateral epicondyle (LE) for the treatment of patients with LE. METHODS: We included 24 patients with LE who reported pain in this study. All patients underwent sonographically-guided percutaneous bone drilling of the lateral epicondyle. Follow-up sonography and physical examinations were performed 1, 3 and 6 months after the procedure. The outcome measures included sonographic findings, visual analogue scale (VAS) score, maximum voluntary grip strength (MVGS) and patient-related tennis elbow evaluation (PRTEE) score. RESULTS: None of the patients had immediate complications during the procedure. The area of the extensor carpi radialis brevis (ECRB) tears decreased significantly at 1 month and declined gradually over the remaining 5 months of the study (p < 0.001). The mean pain VAS score was significantly lower at 6 months than preoperatively (respectively; p < 0.001). The mean MVGS increased significantly between pretreatment and 6 months post-treatment (p < 0.001), whereas the PRTEE score decreased significantly during the same period (p < 0.001). CONCLUSION: Sonographically-guided percutaneous drilling is a quick and safe treatment option for LE that can be performed in an outpatient setting. KEY POINTS: • Percutaneous drilling of the lateral condyle is effective for the treatment of LE. • The area of ECRB tears can be measured by US-guided saline injection. • US-guided percutaneous drilling is a quick and safe treatment option for LE.

Efficacy of double inversion recovery magnetic resonance imaging for the evaluation of the synovium in the femoro-patellar joint without contrast enhancement.

OBJECTIVE: To investigate the efficacy of double inversion recovery (DIR) sequence for evaluating the synovium of the femoro-patellar joint without contrast enhancement (CE). METHODS: Two radiologists independently evaluated the axial DIR and CE T1-weighted fat-saturated (CET1FS) images of 33 knees for agreement; the visualisation and distribution of the synovium were evaluated using a four-point visual scaling system at each of the five levels of the femoro-patellar joint and the location of the thickest synovium. The maximal synovial thickness at each sequence was measured by consensus. RESULTS: The interobserver agreement was good (κ = 0.736) for the four-point scale, and was excellent for the location of the thickest synovium on DIR and CET1FS (κ = 0.955 and 0.954). The intersequential agreement for the area with the thickest synovium was also excellent (κ = 0.845 and κ = 0.828). The synovial thickness on each sequence showed excellent correlation (r = 0.872). CONCLUSION: The DIR showed as good a correlation as CET1FS for the evaluation of the synovium at the femoro-patellar joint. DIR may be a useful MR technique for evaluating the synovium without CE. KEY POINTS: • DIR can be useful for evaluating the synovium of the femoro-patellar joint. • Interobserver and intersequential agreements between DIR and CET1FS were good. • Mean thickness of the synovium was significantly different between two sequences.

3D Ultrashort TE MRI for Evaluation of Cartilaginous Endplate of Cervical Disk In Vivo: Feasibility and Correlation With Disk Degeneration in T2-Weighted Spin-Echo Sequence.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of 3D ultrashort TE (UTE) MRI in depicting the cartilaginous endplate (CEP) and its abnormalities and to investigate the association between CEP abnormalities and disk degeneration on T2-weighted spin-echo (SE) MR images in cervical disks in vivo. SUBJECTS AND METHODS: Eight healthy volunteers and 70 patients were examined using 3-T MRI with the 3D UTE cones trajectory technique (TR/TE, 16.1/0.032, 6.6). In the volunteer study, quantitative and qualitative assessments of CEP depiction were conducted for the 3D UTE and T2-weighted SE imaging. In the patient study, CEP abnormalities were analyzed. Intersequence agreement between the images obtained with the first-echo 3D UTE sequence and the images created by subtracting the second-echo from the first-echo 3D UTE sequence (subtracted 3D UTE) and the intraobserver and interobserver agreements for 3D UTE overall were also tested. The CEP abnormalities on the 3D UTE images correlated with the Miyazaki grading of the T2-weighted SE images. RESULTS: In the volunteer study, the CEP was well visualized on 3D UTE images but not on T2-weighted SE images (p < 0.001). In the patient study, for evaluation of CEP abnormalities, intersequence agreements were substantial to almost perfect, intraobserver agreements were substantial to almost perfect, and interobserver agreements were moderate to substantial (p < 0.001). All of the CEP abnormalities correlated with the Miyazaki grade with statistical significance (p < 0.001). CONCLUSION: Three-dimensional UTE MRI feasibly depicts the CEP and CEP abnormalities, which may be associated with the severity of disk degeneration on T2-weighted SE MRI.

The prevalence and characteristics of a subcortical cystic lesion at the subspinous region of the knee.

Background Although we observed that subcortical cysts near the attachment of the meniscus or cruciate ligaments are frequently seen with a tear or degeneration of the adjacent meniscus and/or cruciate ligament, there is no large study describing the prevalence, distribution, and associated findings of these cysts. Purpose To evaluate the prevalence and distribution of subcortical cysts near the attachments of the meniscus or cruciate ligaments and evaluate pathologies of the meniscus or cruciate ligaments using magnetic resonance imaging (MRI). Material and Methods We reviewed 1009 knee MRIs for the presence of subcortical cysts near the meniscus or cruciate ligament attachments and evaluated their size, location, edema of the adjacent bone marrow, and integrities of the medial and lateral meniscus and anterior and posterior cruciate ligaments. Results The 110 cysts were found in either the middle (n = 56), posterior (n = 52), or anterior (n = 2) subspinous regions. Sixty-two were at meniscal root insertion, including seven at the lateral meniscus anterior horn, five at the lateral meniscus posterior horn, 48 at the medial meniscus posterior horn, and two at the medial meniscus anterior horn. All were associated with an adjacent meniscal pathology. Of the 34 cysts at the anterior cruciate ligament (ACL) insertion, 28 had ACL pathology. Nine cysts had surrounding edema in the adjacent bone marrow. Conclusion Subcortical cysts at the subspinous region of the knee were seen in 9.6% of knee MRI examinations. Most were in close proximity to the meniscal or cruciate ligaments with associated pathologies, suggesting that abnormal stress on the bone induces cyst formation.

Topographical and sex variations in the T2 relaxation times of articular cartilage in the ankle joints of healthy young adults using 3.0T MRI.

PURPOSE: To prospectively evaluate topographical and sex variations in the T2 relaxation values of tibiotalar cartilage (TTC) of healthy young adults. MATERIALS AND METHODS: Sagittal 8-echo multiecho spin-echo T2 maps of TTC were acquired using a 3.0T MR in 25 male and 25 female healthy young adult participants. Quantitative measurements of T2 values in tibial cartilage (TBC) and talar cartilage (TLC) were obtained from three zones (anterior zone, AZ; middle zone, MZ; and posterior zone, PZ) and from four compartments (medial compartment, MC; midmedial compartment, MMC; midlateral compartment, MLC; and lateral compartment, LC) of TBC and TLC in the sagittal plane. RESULTS: The T2 values of AZ (for TBC, 29.31 msec; for TLC, 35.81 msec) and MZ (for TBC, 28.56 msec; for TLC, 36.12 msec) in males were significantly higher than those in females (for AZ of TBC, 26.99 msec; for AZ of TLC, 33.56 msec; for MZ of TBC, 25.88 msec; for MZ of TLC, 31.85 msec) (for TBC, AZ, P = 0.009, MZ, P = 0.002; for TLC, AZ, P = 0.047, MZ, P = 0.001). Except for MMC and MLC of TBC (MMC, P = 0.02, MLC, P = 0.03), TTC T2 values did not differ significantly between these compartment in either group (for TBC, MC, P = 0.27, LC, P = 0.37; for TLC, MC, P = 0.26, MMC, P = 0.08, MLC, P = 0.30, LC, P = 0.10). CONCLUSION: We found significant sex and topographic variations among TTC T2 values of healthy young adults. Acknowledgment of the significant topographical and sex variations in cartilage T2 values may minimize misinterpretation of ankle joint TTC T2 mapping data.

T2 Relaxation Values of the Talar Trochlear Articular Cartilage: Comparison Between Patients With Lateral Instability of the Ankle Joint and Healthy Volunteers.

OBJECTIVE: The purpose of this study was to evaluate the difference between the T2 relaxation values of the talar trochlear cartilage in patients with lateral instability of the ankle joint and the values in healthy volunteers. MATERIALS AND METHODS: A retrospective assessment was conducted of images from 13 MRI examinations of the ankles of 12 patients who underwent lateral ankle ligament repair with an arthroscopically proven normal talar trochlear cartilage. Thirteen ankle MRI examinations of 12 healthy age- and sex-matched volunteers were prospectively performed. Two radiologists independently measured the T2 relaxation values of the talar trochlear cartilage in two layers (superficial and deep) in the following six compartments: medial anterior (M1), medial middle (M2), medial posterior (M3), lateral anterior (L1), lateral middle (L2), and lateral posterior (L3). The T2 relaxation values of patients were compared with those of healthy volunteers. RESULTS: Both readers found that the mean T2 relaxation values of all six compartments of the superficial layer were significantly higher in patients than in control subjects. For reader 1, the M1 findings were 46.2 for patients and 39.6 for healthy volunteers; M2, 50.4 and 41.1; M3, 52.1 and 46.2; L1, 43.1 and 37.9; L2, 47.8 and 41.8; and L3, 53.8 and 49.8. For reader 2, the M1 findings were 45.0 and 40.2; M2, 48.8 and 41.1; M3, 53.2 and 45.6; L1, 42.8 and 38.5; L2, 48.0 and 42.1; and L3, 55.0 and 49.0 (p < 0.05). For the deep layer, the mean T2 relaxation values of M2 (patients, 32.6; volunteers, 27.8 [p = 0.004]) and M3 (patients, 38.3; volunteers, 35.0 [p = 0.046]) for reader 1 and M2 (patients, 31.6; volunteers, 28.7 [p = 0.041]) for reader 2 were significantly higher in patients than in control subjects. Intraobserver and interobserver variability were excellent, except for interobserver variability for M1 deep (0.79) and L1 deep (0.75). CONCLUSION: The T2 relaxation values of arthroscopically proven normal talar trochlear cartilage of patients with lateral instability were higher than those of healthy volunteers, especially in the superficial layer and the M2 deep layer.

Three-dimensional isotropic T2-weighted fast spin-echo (VISTA) knee MRI at 3.0 T in the evaluation of the anterior cruciate ligament injury with additional views: comparison with two-dimensional fast spin-echo T2-weighted sequences.

Background There has been no comparison study to assess the diagnostic efficacy of additional anterior cruciate ligament (ACL) views in three-dimensional (3D) volume isotropic turbo spin-echo acquisition (VISTA) and two-dimensional (2D) fast spin-echo (FSE) T2-weighted (T2W) images for the diagnosis of ACL tear. Purpose To compare the diagnostic performances of additional ACL views on VISTA with those on the 2D FSE T2W images. Material and Methods This retrospective study included 78 patients who were suspected to have ACL injury and underwent both 2D TSE T2W magnetic resonance imaging (MRI) and 3D VISTA MRI of the knee between November 2012 and March 2013. The diagnostic performance of each oblique sagittal and coronal view and the combined images was evaluated for sensitivity, specificity, and accuracy for diagnosing an ACL tear. The arthroscopically and clinically confirmed diagnoses were used as the reference standard. The values were statistically analyzed using the McNemar test. Results The inter-observer agreement between two readers of the additional ACL views on 3D VISTA and 2D FSE T2W images were substantial on 2D FSE images and nearly concurred on the VISTA image. When considering both views of the oblique sagittal and coronal images, the inter-observer agreement between readers nearly concurred. There were no statistically significant differences in the sensitivity, specificity, and accuracy between 2D FSE images and VISTA images. Conclusion The performance of the additional ACL view on 3D VISTA MRI is comparable to that of 2D FSE T2W MRI in the diagnosis of ACL tear though the image quality of the 3D VISTA MRI is not equal to that of 2D FSE MRI.

Magnetic resonance elastography (MRE) for measurement of muscle stiffness of the shoulder: feasibility with a 3 T MRI system.

BACKGROUND: Magnetic resonance elastography (MRE) at 3 T MR has the potential to improve the objective detection of skeletal muscle stiffness. PURPOSE: To determine the feasibility of MRE using 3 T MR for measurement of the stiffness of shoulder muscles in subjects. MATERIAL AND METHODS: This study prospectively evaluated 16 healthy subjects (mean age, 29.8 years; range, 25-51 years). MRE was acquired with 3 T MR through the use of a 2D-gradient-echo-based MRE sequence at two different excitation frequencies (90 and 120 Hz). The mean stiffness values (MSV) of the trapezius and infraspinatus muscles were measured by two radiologists. Differences between the MSV in the x, y, and z motion-sensitization directions were assessed. Inter-observer agreement was also measured. RESULTS: The MSV of the trapezius muscle were 2.72 kPa ± 0.6 (SD) at 90 Hz and 4.66 kPa ± 1.2 at 120 Hz, while the MSV for the infraspinatus muscle were 3.2 kPa ± 0.52 at 90 Hz and 4.38 kPa ± 0.92 at 120 Hz. The MSV for both muscles were significantly higher at 120 Hz than at 90 Hz (P < 0.05). The MSV in the three different directions were significantly different from each other in the infraspinatus muscle (P < 0.05). Levels of inter-observer agreement regarding MSV were good to excellent for both the trapezius (intraclass correlation coefficient [ICC] = 0.979-0.996) and infraspinatus muscles (ICC = 0.614-0.943). CONCLUSION: MRE at 3 T is a feasible technique for the evaluation of shoulder muscle stiffness. Extended application of skeletal muscle MRE at 3 T will contribute to the evaluation and treatment of skeletal muscle disorders.

Diagnostic performance of abdominal CT for diagnosis of pelvic fractures: comparison with pelvic CT.

BACKGROUND: In the emergency department, patients with abdominopelvic trauma inadvertently undergo both abdominal computed tomography (CT) (for intra-abdominal and intra-pelvic organs) and pelvic CT (CT with multiplanar reformation in three orthogonal planes of the bony pelvis). However, the systemic use of CT is concerning given the cumulative radiation dose. PURPOSE: To evaluate the diagnostic value of abdominal CT in comparison to pelvic CT in patients with suspected pelvic fractures. MATERIAL AND METHODS: Seventy-two patients who underwent abdominal CT and pelvic CT within a 2-week period to evaluate pelvic fractures were included. Two reviewers retrospectively analyzed eight anatomical regions of the pelvic bones on both abdominal CT and pelvic CT over a 1-week interval. The interpretation of pelvic CT scans by two senior musculoskeletal radiologists was considered as the reference standard. Diagnostic performance and inter-observer agreement of both CT scans were evaluated. RESULTS: For reviewers 1 and 2, abdominal CT showed high accuracy (98% and 98%, respectively) as did pelvic CT. For both abdominal CT and pelvic CT, fracture detection in all anatomical regions of the pelvic bones was not significantly different for the two reviewers (P ≥ 0.25). Inter-observer agreement for all anatomical regions of the pelvic bones was excellent or good (k = 0.785-1.0). CONCLUSION: Not only pelvic CT but also abdominal CT is acceptable for detection of pelvic fractures, in spite of its thicker sections and different reconstruction algorithm. Therefore, if abdominal CT has already been performed, additional pelvic CT might no longer be necessary in order to exclude a pelvic fracture.

MRI of the anterior talofibular ligament, talar cartilage and os subfibulare: Comparison of isotropic resolution 3D and conventional 2D T2-weighted fast spin-echo sequences at 3.0 T.

PURPOSE: To determine the accuracy of a three-dimensional (3D) T2-weighted fast spin-echo (FSE) magnetic resonance (MR) sequence compared with two-dimensional (2D) sequence for diagnosing anterior talofibular ligament (ATFL) tears, chondral lesion of the talus (CLT) and os subfibulare/avulsion fracture of the distal fibula (OSF). MATERIALS AND METHODS: Thirty-five patients were included, who had undergone ankle MRI with 3D T2-weighted FSE and 2D T2-weighted FSE sequences, as well as subsequent ankle arthroscopy, between November 2013 and July 2014. Each MR imaging sequence was independently scored by two readers retrospectively for the presence of ATFL tears, CLT and OSF. The area under the receiver operating curve (AUC) was compared to determine the discriminatory power of the two image sequences. Interobserver agreement was expressed as unweighted kappa value. RESULTS: Arthroscopic findings confirmed 21 complete tears of the ATFL, 14 partial tears of the ATFL, 17 CLTs and 7 OSFs. There were no significant differences in the diagnoses of ATFL tears (p = 0.074-0.501), CLT (p = 0.090-0.450) and OSF (p = 0.317) obtained from the 2D and 3D sequences by either reader. The interobserver agreement rates between two readers using the 3D T2-weighted FSE sequence versus those obtained with the 2D sequence were substantial (κ = 0.659) versus moderate (κ = 0.553) for ATFL tears, moderate (κ = 0.499) versus substantial (κ = 0.676) for CLT and substantial (κ = 0.621) versus substantial (κ = 0.689) for OSF. CONCLUSION: Three-dimensional isotropic T2-weighted FSE MRI of the ankle resulted in no statistically significant difference in diagnostic performance compared to two-dimensional T2-weighted FSE MRI in the evaluation of ATFL tears, CLTs and OSFs.

Comparison of Quantitative Cartilage T2 Measurements and Qualitative MR Imaging between Professional Ballet Dancers and Healthy Volunteers.

PURPOSE: To compare qualitative magnetic resonance (MR) images and quantitative T2 measurements of the tibiotalar cartilage between ballerinas and healthy volunteers. MATERIALS AND METHODS: Institutional review board approval for this study and informed consent (from all participants) were obtained. MR examinations were performed by using a 3-T MR imaging system with 21 professional female ballet dancers and 20 healthy female volunteers. Two musculoskeletal radiologists qualitatively measured tibiotalar cartilage T2 values in the anterior zones, middle zones, and posterior zones of cartilage. MR findings were also qualitatively analyzed in both groups. RESULTS: The tibial cartilage T2 values measured in the anterior and posterior zones and the talar cartilage T2 values measured in all three zones were significantly higher in the ballerina group than in the control group (P < .001). The posterior zones exhibited the highest T2 values among the three tibiotalar cartilage zones in both groups (P < .001). A significant between-group difference was evident in terms of the presence of posterior soft-tissue edema (P = .001) and flexor hallucis longus tenosynovitis (P < .001). CONCLUSION: The findings showed a trend toward increasing cartilage T2 values in ballerinas when compared with control subjects, indicating that quantitative T2 measurement may potentially be used as a noninvasive imaging tool for early detection of cartilage lesions in the tibiotalar joint.

Differential Diagnosis of Chronic Total Occlusive and Subtotal Occlusive Disease of the Lower Extremity Arteries Using Reverse Attenuation Gradient Sign on CT Angiography.

OBJECTIVE: The purpose of this study is to evaluate the diagnostic usefulness of the reverse attenuation gradient sign in occlusive lower extremity arterial disease through CT angiography (CTA). MATERIALS AND METHODS: This study sample enrolled 45 men and eight women in the chronic total occlusion group and 30 men and seven women in the subtotal occlusion group. Luminal CT attenuation (in Hounsfield units) was measured at three points from the end of the occlusion site to the first collateral vessel's insertion point. We also used Hounsfield units to measure the CT attenuation of the opposite side artery at the same level in a similar manner. We compared each value using the Mann-Whitney U test. RESULTS: The absolute value of the mean differences in the Hounsfield units among the proximal, middle, and distal portion of chronic total occlusions were higher than those of subtotal occlusions, and this result was statistically significant (p < 0.001). The mean ratios of the Hounsfield units (Hounsfield units of the stenosed lumen divided by Hounsfield units of the opposite normal lumen) of the proximal portion of chronic total occlusions were statistically significantly lower than those of subtotal occlusions. CONCLUSION: The reverse attenuation gradient sign can be applied to the lower extremity arteries and can be helpful for differential diagnosis of chronic total occlusions from subtotal occlusions using CTA.

Usefulness of oblique coronal and sagittal MR images of the knee after double-bundle and selective anterior cruciate ligament reconstructions.

BACKGROUND: The use of double-bundle and selective-bundle anterior cruciate ligament (ACL) reconstruction is increasing. Few studies have been conducted to determine the diagnostic efficacy of additional oblique views of knee magnetic resonance imaging (MRI) for grading ACL graft injury for double-bundle and selective-bundle ACL reconstructions. PURPOSE: To evaluate the diagnostic value of combining oblique coronal and sagittal imaging with orthogonal views for diagnosis of ACL graft failure after double-bundle or selective-bundle ACL reconstruction. MATERIAL AND METHODS: This retrospective study included 64 patients who underwent double-bundle or selective-bundle ACL reconstruction surgery and received oblique coronal and oblique sagittal MRI of the knee. Subjective scoring of the images was performed by two radiologists who assessed the possibility of ACL graft failure based on full length view, full width view, and margin sharpness according to a 4-point scale. Diagnostic performance for ACL graft failure based on orthogonal views alone, ACL views alone, and orthogonal views with additional ACL views was evaluated by calculating the sensitivity, specificity, and accuracy. RESULTS: The full length scores and total scores on ACL views were significantly higher than those of orthogonal views. The specificities and accuracies of diagnoses were highest for a combination of orthogonal, ACL sagittal, and ACL coronal views. CONCLUSION: After double-bundle or selective-bundle ACL reconstruction, oblique sagittal and coronal images of the ACL provide better anatomic evaluation of the ACL than orthogonal views and specificity and accuracy of diagnoses were improved when oblique views were combined.