Opportunistic Screening for Acute Vertebral Fractures on a Routine Abdominal or Chest Computed Tomography Scans Using an Automated Deep Learning Model.

OBJECTIVES: To develop an opportunistic screening model based on a deep learning algorithm to detect recent vertebral fractures in abdominal or chest CTs. MATERIALS AND METHODS: A total of 1309 coronal reformatted images (504 with a recent fracture from 119 patients, and 805 without fracture from 115 patients), from torso CTs, performed from September 2018 to April 2022, on patients who also had a spine MRI within two months, were included. Two readers participated in image selection and manually labeled the fractured segment on each selected image with Neuro-T (version 2.3.3; Neurocle Inc.) software. We split the images randomly into the training and internal test set (labeled: unlabeled = 480:700) and the secondary interval validation set (24:105). For the observer study, three radiologists reviewed the CT images in the external test set with and without deep learning assistance and scored the likelihood of an acute fracture in each image independently. RESULTS: For the training and internal test sets, the AI achieved a 99.86% test accuracy, 91.22% precision, and 89.18% F1 score for detection of recent fracture. Then, in the secondary internal validation set, it achieved 99.90%, 74.93%, and 78.30%, respectively. In the observer study, with the assistance of the deep learning algorithm, a significant improvement was observed in the radiology resident's accuracy, from 92.79% to 98.2% (p = 0.04). CONCLUSION: The model showed a high level of accuracy in the test set and also the internal validation set. If this algorithm is applied opportunistically to daily torso CT evaluation, it will be helpful for the early detection of fractures that require treatment.

Histiocytic sarcoma mimicking localized tenosynovial giant cell tumor in the pediatric foot: A rare case report with MRI Findings.

We present a rare case of histiocytic sarcoma (HS) occurring in the foot of a 12-year-old male, initially misdiagnosed as localized tenosynovial giant cell tumor (TSGCT). HS is an exceptionally uncommon hematologic malignant neoplasm, with its occurrence in children and extranodal sites being even rarer. To our knowledge, this is the first reported case of extranodal HS in the foot, emphasizing comprehensive MRI findings. Initially, the patient was diagnosed with TSGCT based on histological results following surgical resection. However, after recurrence and subsequent surgical resection, histological and immunochemical analyses led to a revised diagnosis of HS. This report focuses on the MRI findings of HS, highlighting the distinctions from localized TSGCT. While both conditions share histopathological similarities, immunohistochemical tests are crucial for accurate diagnosis. The report underscores the importance of differentiating HS for appropriate treatment.

Ultrashort echo time pulse sequences for visualization of deep peripheral fasciae and epimysium in porcine models with histologic correlations.

Background: The deep peripheral fascia and epimysium are vital for muscle and tendon support, but their tight proton composition results in hypointense signals in conventional spin echo sequences. Ultrashort echo time (UTE) magnetic resonance imaging (MRI), using microsecond TE values, may visualize these structures. The purpose of this study was to evaluate whether UTE pulse sequence with a three-dimensional cone trajectory (3D UTE), with or without fat suppression (FS), can be used to visualize the fascia and epimysium using porcine lower legs as an example. Methods: The anterior soft tissues of porcine lower legs were dissected and partially separated into distinct layers to expose the deep peripheral fascia, epimysium, and muscle. Axial 3D UTE and 3D UTE FS imaging using dual-echo acquisition and echo subtraction were performed both before and after dissection. Prior to dissection, the thickness, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs) of structures believed to be deep peripheral fascia and epimysium were measured in both 3D UTE and 3D UTE FS. Post-dissection images were also analyzed to measure the SNRs and CNRs for the deep peripheral fascia and epimysium. Histological evaluations were carried out to verify the identities of the deep peripheral fascia and epimysium, as well as their thickness, and these measurements were compared to imaging findings. Results: In pre-dissection images obtained with 3D UTE and 3D UTE FS, both the deep peripheral fascia and epimysium exhibited high signal intensity. In the subtraction images, the mean thickness of the deep fascia was 0.87 mm, and that of the epimysium was 0.80 mm when imaged with 3D UTE. This is compared to measurements of 0.77 and 0.22 mm in 3D UTE FS, respectively. Histological analyses confirmed the thickness of the deep peripheral fascia and epimysium as 0.65 and 0.14 mm, respectively. In the post-dissection images, the deep fascia continued to display high signal intensity when compared with adjacent soft tissues, consistent with the histological findings. Meanwhile, the epimysium showed very low CNRs. Conclusions: 3D UTE and 3D UTE FS can be used to visualize the deep peripheral fascia with high signal intensity and contrast but are insufficient to show signal intensity in the epimysium.

Deep learning system for automated detection of posterior ligamentous complex injury in patients with thoracolumbar fracture on MRI.

This study aimed to develop a deep learning (DL) algorithm for automated detection and localization of posterior ligamentous complex (PLC) injury in patients with acute thoracolumbar (TL) fracture on magnetic resonance imaging (MRI) and evaluate its diagnostic performance. In this retrospective multicenter study, using midline sagittal T2-weighted image with fracture (± PLC injury), a training dataset and internal and external validation sets of 300, 100, and 100 patients, were constructed with equal numbers of injured and normal PLCs. The DL algorithm was developed through two steps (Attention U-net and Inception-ResNet-V2). We evaluate the diagnostic performance for PLC injury between the DL algorithm and radiologists with different levels of experience. The area under the curves (AUCs) generated by the DL algorithm were 0.928, 0.916 for internal and external validations, and by two radiologists for observer performance test were 0.930, 0.830, respectively. Although no significant difference was found in diagnosing PLC injury between the DL algorithm and radiologists, the DL algorithm exhibited a trend of higher AUC than the radiology trainee. Notably, the radiology trainee's diagnostic performance significantly improved with DL algorithm assistance. Therefore, the DL algorithm exhibited high diagnostic performance in detecting PLC injuries in acute TL fractures.

MRI Findings of Periarticular Lesions with Isolated Greater Tubercle Fractures and Dislocation.

PURPOSE: To identify MRI findings for injuries to periarticular soft tissue structures that were related to isolated greater tubercle fracture. MATERIALS AND METHODS: 16 patients (mean age: 53.8, range 30-71 yrs) were enrolled and diagnosed with isolated greater tubercle (GT) fracture with CT and MRI and underwent shoulder arthroscopy from September 2009 to April 2019. Two musculoskeletal radiologists were blinded to the patient history and arthroscopic surgical findings and reviewed patient's CT and MRI. Fracture displacement, fracture center, and presence of bony Bankart lesion with Hill sachs lesion were checked on shoulder CT. Soft tissue injuries, including rotator cuff injury, deltoid muscle injury, long head of biceps tendon injury, capsular injury, glenoid injury, and injury location of the subscapularis and infraspinatus were checked on shoulder MRI. RESULTS: MRI showed supraspinatus injury (56.3%), subscapularis injury (56.3%), deltoid muscle injury (25%), infraspinatus injury (25%), teres minor muscle injury (37.5%), injury of the long head of the biceps tendon (43.8%), inferior glenohumeral ligament tear (87.5%), superior labral anterior-toposterior lesion (25%), Bankart lesion (18.8%), and Hill-Sachs lesion (6.3%). 88.9% of subscapularis injuries and 75% of infraspinatus injuries showed caudal predominance. All of the patients with infraspinatus injuries showed concomitant teres minor muscle injuries. In order of frequency, the fracture centers were anterior (25%), posterior (31.3%), and all (43.8%). For patients with Bankart and Hill- Sachs lesions, the fracture center included the posterior portion in all cases. CONCLUSION: MRI and active arthroscopic examinations may be valuable when an isolated GT avulsion fracture is identified on X-ray examination.

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.

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.

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.

Extradural Spinal Lymphoplasmacyte-Rich Meningioma in the Thoracic Spine: A Case Report and Literature Review.

Most spinal meningiomas have an intradural or partly extradural location. The meningothelial origin is the most common pathologic type of spinal meningioma. Pure extradural spinal meningiomas are not common, and lymphoplasmacyte-rich meningioma (LPRM) is very rare. We report a case of isolated extradural spinal meningioma in the thoracic spine that was pathologically confirmed as LPRM.

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.

Intraosseous ganglion cyst mimicking chondrosarcoma on MRI: a case report.

BACKGROUND: The intraosseous ganglia is a benign cyst, rarely locate in the olecranon process. As intraosseous ganglia can mimic malignant bone tumor, computed tomography (CT) is important for diagnosis even when magnetic resonance imaging (MRI) suggests malignant bone tumor, such as chondrosarcoma. CASE PRESENTATION: In this paper, we report a 42-year-old woman with intraosseous ganglia in the olecranon process of the ulna. She complained pain in right elbow for 3 weeks. MRI revealed an intraosseous mass which initially diagnosed as chondrosarcoma. However, followed computed tomography (CT) demonstrated scattered intralesional gas and no underlying mineralization, and we can exclude chondrosarcoma from diagnosis. CONCLUSIONS: The intraosseous ganglia can mimic bone tumor in MRI; therefore, CT is essential for accurate characterization of bone tumor. Even if MR imaging strongly suggests chondrosarcoma of the bone, CT should be performed as additional study.

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.

The potential for reduced radiation dose from deep learning-based CT image reconstruction: A comparison with filtered back projection and hybrid iterative reconstruction using a phantom.

ABSTRACT: The purpose of this phantom study is to compare radiation dose and image quality of abdominal computed tomography (CT) scanned with different tube voltages and tube currents, reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (IR) and deep learning image reconstruction (DLIR) algorithms.A total of 15 CT scans of whole body phantoms were taken with 3 different tube voltages and 5 different tube currents. The images were reconstructed with FBP, 30% and 50% hybrid IR adaptive statistical iterative reconstruction (ASIR-V), and low, medium and high strength DLIR algorithms. The image scanned with tube voltage/tube current of 120 kV/ 200 mA and reconstructed with FBP algorithm was chosen as the reference image. Five radiologists independently analyzed the images individually and also compared it with the reference image in overall, using the visual grading analysis. The mean score of each image was calculated and compared.Using DLIR algorithms, the radiation dose was reduced by 65.5% to 68.1% compared with the dose used in the reference image, while maintaining comparable image quality. Using the DLIR algorithm of medium strength, the image quality was even better than the reference image with a reduced radiation dose up to 36.2% to 50.0%. The DLIR algorithms generated better quality images than ASIR-V algorithms in all the data sets. In addition, among the data sets reconstructed with DLIR algorithms, image quality was the best at the medium strength level, followed by low and high.This phantom study suggests that DLIR algorithms may be considered as a new reconstruction technique by reducing radiation dose while maintaining the image quality of abdominal CTs.

Depiction of the Periosteum Using Ultrashort Echo Time Pulse Sequence with Three-Dimensional Cone Trajectory and Histologic Correlation in a Porcine Model.

OBJECTIVE: To evaluate the signal intensity of the periosteum using ultrashort echo time pulse sequence with three-dimensional cone trajectory (3D UTE) with or without fat suppression (FS) to distinguish from artifacts in porcine tibias. MATERIALS AND METHODS: The periosteum and overlying soft tissue of three porcine lower legs were partially peeled away from the tibial cortex. Another porcine tibia was prepared as three segments: with an intact periosteum outer and inner layer, with an intact periosteum inner layer, and without periosteum. Axial T1 weighted sequence (T1 WI) and 3D UTE (FS) were performed. Another porcine tibia without periosteum was prepared and subjected to 3D UTE (FS) and T1 WI twice, with positional changes. Two radiologists analyzed images to reach a consensus. RESULTS: The three periosteal tissues that were partially peeled away from the cortex showed a high signal in 3D UTE (FS) and low signal on T1 WI. 3D UTE (FS) showed a high signal around the cortical surface with an intact outer and inner periosteum, and subtle high signals, mainly around the upper cortical surfaces with the inner layer of the periosteum and without periosteum. T1 WI showed no signal around the cortical surfaces, regardless of the periosteum state. The porcine tibia without periosteum showed changes in the high signal area around the cortical surface as the position changed in 3D UTE (FS). No signal was detected around the cortical surface in T1 WI, regardless of the position change. CONCLUSION: The periosteum showed a high signal in 3D UTE and 3D UTE FS that overlapped with artifacts around the cortical bone.

Early Imaging Findings of Hypertrophic Osteoarthropathy Mimicking Bone Metastasis from Extrathoracic Malignancy.

Hypertrophic osteoarthropathy (HOA) is a syndrome characterized by digital clubbing, periosteal bone formation, and synovial effusions. Secondary HOA is associated with intrathoracic malignancy in most cases; however, in rare cases, HOA can be caused by extrathoracic conditions. We report early ultrasound, computed tomography, magnetic resonance imaging, and bone scintigraphy findings of HOA in a patient with breast cancer. Its ambiguous clinical and imaging findings that mimicked malignant conditions are particularly interesting and informative.

Characterization of small, deeply located soft-tissue tumors: Conventional magnetic resonance imaging features and apparent diffusion coefficient for differentiation between non-malignancy and malignancy.

OBJECTIVES: To compare magnetic resonance imaging (MRI) parameters of small, deeply located non-malignant and malignant soft-tissue tumors (STTs). METHODS: Between May 2011 and December 2017, 95 MRIs in 95 patients with pathologically proven STTs of small size (<5 cm) and deep location (66 non-malignant and 29 malignant) were identified. For qualitative parameters, consensus reading was performed by three radiologists for presence of necrosis, infiltration, lobulation, and the tail sign. Apparent diffusion coefficient (ADC) was analyzed by two other radiologists independently. Univariable and multivariable analyses were performed to determine the diagnostic performances of MRI parameters in differentiating non-malignancy and malignancy, and for non-myxoid, non-hemosiderin STTs and myxoid STTs as subgroups. Interobserver agreement for ADC measurement was calculated with the intraclass correlation coefficient. RESULTS: Interobserver agreement on ADC measurement was almost perfect. On univariable analysis, the malignant group showed a significantly larger size, lower ADC, and higher incidence of all qualitative MRI parameters for all STTs. Size (p = 0.012, odds ratio [OR] 2.57), ADC (p = 0.041, OR 3.85), and the tail sign (p = 0.009, OR 6.47) were independently significant on multivariable analysis. For non-myxoid, non-hemosiderin STTs, age, size, ADC, frequency of infiltration, lobulation, and the tail sign showed significant differences between non-malignancy and malignancy on univariable analysis. Only ADC (p = 0.032, OR 142.86) retained its independence on multivariable analysis. For myxoid STTs, only size and tail sign were significant on univariable analysis without independent significance. CONCLUSIONS: Size, ADC, and incidence of qualitative MRI parameters were significantly different between small, deeply located non-malignant and malignant STTs. Only ADC was independently significant for both overall analysis and the non-myxoid, non-hemosiderin subgroup.

Evaluation of the anterior inferior tibiofibular and anterior talofibular ligaments using 2D oblique coronal imaging and 3D isotropic resolution T2-weighted fast spin-echo sequences at 3.0 T: Is there additional diagnostic value?

INTRODUCTION: To compare diagnostic performance of additional two-dimensional (2D) oblique coronal view and three-dimensional (3D) T2-weighted fast spin-echo(FSE) images for diagnosing injury of the anterior inferior tibiofibular (AiTFL) and anterior talofibular ligaments (ATFL). METHODS: This study included 48 patients with ankle sprain who had undergone MRI using standard protocol and two additional sequences with 2D oblique coronal and 3D isotropic images, followed by arthroscopic surgery. Ligament injuries was subdivided by intact tendon, partial or complete tear. Retrospectively, two musculoskeletal radiologists respectively reviewed three image sets of MR including 2D axial image only (set 1), 2D axial and oblique coronal images (set 2), and 2D axial with 3D-isotropic images (set 3). Using arthroscopic findings as reference standard, diagnostic performances of both methods were analysed by the area under the curve (AUC). RESULTS: Arthroscopy confirmed 13 AiTFL and 41 ATFL injuries. For AiTFL, when set 1 and set 3 were compared, AUC value was significantly higher for set 3 (P < 0.05). However, there was no significant difference between AUC values for set 2 and set 3 sequences by either reader for either type of tear (P > 0.05). For ATFL, both readers found there was no significant difference in AUC values between set 1 and set 3 and between set 2 and set 3. CONCLUSION: Additional oblique coronal sequence demonstrated better diagnostic performance for AiTFL injury than conventional and isotropic imaging did. This sequence showed as much diagnostic accuracy as isotropic sequence for evaluation of ATFL injury.

Shear-Wave and Strain Ultrasound Elastography of the Supraspinatus and Infraspinatus Tendons in Patients with Idiopathic Adhesive Capsulitis of the Shoulder: A Prospective Case-Control Study.

OBJECTIVE: To compare the elasticity of the supraspinatus tendon (SST) and infraspinatus tendon (IST) in patients with idiopathic adhesive capsulitis of the shoulder (ACS) with those in the control groups and to evaluate the relationship between age and tendon elasticity. MATERIALS AND METHODS: The Institutional Review Board approved this prospective, case-control study, which was conducted between November 2017 and March 2018, and informed consent was obtained from all participants. Control groups comprised healthy individuals or those with asymptomatic contralateral shoulders. Twenty-five shoulders in 20 participants in the ACS group (14 women; 53.5 ± 7.9 years) and 24 shoulders in 18 participants in the control group (6 women; 52.6 ± 10.5 years) were included. Elastography was performed in the oblique coronal plane at the neutral shoulder position. Mean/maximum/minimum velocity and stiffness from the shear-wave ultrasound elastography (SWE) and strain ratio (subcutaneous fat/target-tendon) from the strain ultrasound elastography (SE) of the SST and IST were evaluated. Statistical analyses were performed using the Mann-Whitney U test, receiver operating characteristic (ROC) curve, and Spearman correlation. RESULTS: Both velocity and stiffness in SWE were higher, and the strain ratio in SE was lower in participants with symptomatic shoulders than in those with normal shoulders (p < 0.001). SST- and IST-mean velocity, mean stiffness, and strain ratios showed excellent area under the ROC curve (> 0.970). The elastic modulus was little correlated with age (ρ = -0.340-0.239). CONCLUSION: SWE and SE indicated that SST and IST were stiffer in patients with ACS than in those with normal shoulders regardless of aging.

Muscle fat quantification using magnetic resonance imaging: case-control study of Charcot-Marie-Tooth disease patients and volunteers.

BACKGROUND: This study aimed to evaluate the potential value of 3D multiple gradient echo Dixon-based magnetic resonance imaging (MRI) sequence as a tool for thigh intramuscular fat quantification in Charcot-Marie-Tooth disease (CMT) patients. METHODS: A prospective comparison study comprising 18 CMT patients and 18 age/sex-matched volunteers was performed. MRI including 3D multiple gradient echo Dixon-based imaging was performed for each subject. Region of interest analyses were performed at the upper and lower third of both thighs. The two-sample t-test or Wilcoxon rank sum test was used for intergroup comparison of the mean muscle fat fraction. Intraclass correlation coefficients were used to evaluate the interobserver agreement and test-retest reproducibility. Semiquantitive analysis using the Goutallier classification (Grades 0-4) was performed on T1-weighted images in upper thigh muscles. For Goutallier Grade 0 muscles, comparison of the mean intramuscular fat fraction between volunteers and CMT patients was performed. RESULTS: The interobserver agreements were excellent for all measurements (intraclass correlation coefficients > 0.8). Mean muscle fat fractions were significantly higher in all the measured muscles of CMT patients (P < 0.05) except in the adductor magnus in the upper thigh (P = 0.109). Goutallier Grade 0 muscles of the CMT patients showed a significantly higher mean fat fraction compared with that of the volunteers (P < 0.05). CONCLUSIONS: 3D multiple gradient echo Dixon-based MRI is a reproducible and sensitive technique which can reveal a significant difference in the fat fraction of thigh muscle, including comparison between Goutallier Grade 0 muscles, between CMT patients and volunteers.

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.