Deep learning to detect anterior cruciate ligament tear on knee MRI: multi-continental external validation.

OBJECTIVES: To develop a deep-learning algorithm for anterior cruciate ligament (ACL) tear detection and to compare its accuracy using two external datasets. METHODS: A database of 19,765 knee MRI scans (17,738 patients) issued from different manufacturers and magnetic fields was used to build a deep learning-based ACL tear detector. Fifteen percent showed partial or complete ACL rupture. Coronal and sagittal fat-suppressed proton density or T2-weighted sequences were used. A Natural Language Processing algorithm was used to automatically label reports associated with each MRI exam. We compared the accuracy of our model on two publicly available external datasets: MRNet, Bien et al, USA (PLoS Med 15:e1002699, 2018); and KneeMRI, Stajduhar et al, Croatia (Comput Methods Prog Biomed 140:151-164, 2017). Receptor operating characteristics (ROC) curves, area under the curve (AUC), sensitivity, specificity, and accuracy were used to evaluate our model. RESULTS: Our neural networks achieved an AUC value of 0.939 for detection of ACL tears, with a sensitivity of 87% (0.875) and a specificity of 91% (0.908). After retraining our model on Bien dataset and Stajduhar dataset, our algorithm achieved AUC of 0.962 (95% CI 0.930-0.988) and 0.922 (95% CI 0.875, 0.962) respectively. Sensitivity, specificity, and accuracy were respectively 85% (95% CI 75-94%, 0.852), 89% (95% CI 82-97%, 0.894), 0.875 (95% CI 0.817-0.933) for Bien dataset, and 68% (95% CI 54-81%, 0.681), 93% (95% CI 89-97%, 0.934), and 0.870 (95% CI 0.821-0.913) for Stajduhar dataset. CONCLUSION: Our algorithm showed high performance in the detection of ACL tears with AUC on two external datasets, demonstrating its generalizability on different manufacturers and populations. This study shows the performance of an algorithm for detecting anterior cruciate ligament tears with an external validation on populations from countries and continents different from the study population. KEY POINTS: • An algorithm for detecting anterior cruciate ligament ruptures was built from a large dataset of nearly 20,000 MRI with AUC values of 0.939, sensitivity of 87%, and specificity of 91%. • This algorithm was tested on two external populations from different other countries: a dataset from an American population and a dataset from a Croatian population. Performance remains high on these two external validation populations (AUC of 0.962 and 0.922 respectively).

[Neuromuscular dynamic scapular winging: Clinical, electromyographic and magnetic resonance imaging diagnosis]. / Scapula alata dynamique d'origine neuromusculaire : diagnostic clinique, électromyographique et à l'imagerie par résonance magnétique.

Dyskinesia of the scapula is a clinical diagnosis and includes all disorders affecting scapula positioning and movement whatever its etiology. Scapular winging is a subtype of scapular dyskinesia due to a dynamic prominence of the medial border of the scapula (DSW) secondary to neuromuscular imbalance in the scapulothoracic stabilizer muscles. The two most common causes of DSW are microtraumatic or idiopathic lesions of the long thoracic nerve (that innerves the serratus anterior) or the accessory nerve (that innerves the trapezius). Diagnosis of DSW is clinical and electromyographic. Use of magnetic resonance imaging (MRI) could be of interest to distinguish lesion secondary to a long thoracic nerve from accessory nerve and to rule out scapular dyskinesia related to other shoulder disorders. Causal neuromuscular lesion diagnosis in DSW is challenging. Clinical examinations, combined with scapular MRI, could help to their specific diagnosis, determining their stage, ruling out differential diagnosis and thus give raise to more targeted treatment.

Is superolateral Hoffa fat pad edema a consequence of impingement between lateral femoral condyle and patellar ligament?

PURPOSE: To evaluate whether knee extensor mechanism features are associated with superolateral Hoffa fat pad edema at magnetic resonance imaging. MATERIALS AND METHODS: Institutional review board approval and written consent from all patients were obtained. Patients with superolateral Hoffa fat pad edema (n = 30) and a control group without edema of the fat pad (n = 60) were evaluated prospectively with magnetic resonance (MR) imaging. Demographic data and extensor mechanism features were compared, including trochlear depth, lateral trochlear inclination, patellar tilt angle, patellar height ratio, distance between patellar ligament and lateral trochlear facet, distance from the tibial tubercle to the trochlear groove, patellar facet asymmetry, and patellar ligament abnormalities. RESULTS: The following variables were associated with superolateral Hoffa fat pad edema in the multivariable models: patellar height ratio (P = .023), shortest distance between patellar ligament and lateral trochlear facet (P < .001), and distance from the tibial tubercle to the trochlear groove (P = .046). Of all demographic and degenerative variables, only age was significantly associated, with younger patients more likely to have superolateral Hoffa fat pad edema (P < .009). CONCLUSION: A high-riding patella, a short distance between the patellar ligament and the lateral trochlear facet, and an increased distance from the tibial tubercle to the trochlear groove are associated with superolateral Hoffa fat pad edema at MR imaging. These results are suggestive of impingement between the lateral femoral condyle and the posterior aspect of the patellar ligament in these patients.

Role of imaging in spine, hand, and wrist osteoarthritis.

Osteoarthritis (OA) of the wrist is mainly secondary to traumatic ligamentous or bone injuries. Involvement of the radiocarpal joint occurs early on in the disease, whereas the mediocarpal joint is involved at a later stage. Metabolic diseases may also involve the wrist and affect specific joints such as the scapho-trapezio-trapezoid joint. Although OA of the wrist is routinely diagnosed on plain films, a thorough assessment of cartilage injuries on computed tomographic arthrography, magnetic resonance imaging (MRI), or MR arthrography remains necessary before any surgical procedure. OA of the fingers is frequently encountered in postmenopausal women. Distal interphalangeal joints and trapezio-metacarpal joint are the most frequently involved joints. Whereas the clinical diagnosis of OA of the wrist and hand is straightforward, the therapeutic management of symptomatic forms remains unclear, with no clear guidelines. OA of the spine is related to degenerative changes of the spine involving the disc space, vertebral endplates, the facet joints, or the supportive and surrounding soft tissues. The sequelae of disc degeneration are among the leading causes of functional incapacity in both sexes, and are a common source of chronic disability in the working years. Disc degeneration involves structural disruption and cell-mediated changes in composition. Radiography remains usually the first-line imaging method. MRI is ideally suited for delineating the presence, extent, and complications of degenerative spinal disease. Other imaging modalities such as computed tomography, dynamic radiography, myelography, and discography may provide complementary information in selected cases, especially before an imaging-guided percutaneous treatment or spinal surgery. The presence of degenerative changes on imaging examinations is by no means an indicator of symptoms, and there is a high prevalence of lesions in asymptomatic individuals. This article focuses on imaging of OA of the wrist and hand, as well as lumbar spine OA, with an emphasis on current MRI grading systems available for the assessment of discovertebral lesions.

Osteoarthritis of the wrist and hand, and spine.

Although osteoarthritis (OA) of the wrist and fingers is routinely diagnosed using plain film, a thorough assessment of cartilage injuries using CT-arthrography, MR imaging, or MR-arthrography remains necessary before any surgical procedure. MR imaging is ideally suited for delineating the presence, extent, and complications of degenerative spinal disease, including OA of the spine involving the disk space, vertebral endplates, facet joints, or supportive and surrounding soft tissues. Other imaging modalities such as CT, dynamic radiography, myelography, and discography may provide complimentary information in selected cases. This article focuses on imaging of OA of the wrist and hand and the lumbar spine, with an emphasis on current MR imaging grading systems available for the assessment of discovertebral lesions.

Uterine fibroid vascularization and clinical relevance to uterine fibroid embolization.

Embolization has become a first-line treatment for symptomatic uterine fibroid tumors. Selective catheterization and embolization of both uterine arteries, which are the predominant source of blood flow to fibroid tumors in most cases, is the cornerstone of treatment. Although embolization for treatment of uterine fibroid tumors is widely accepted, great familiarity with the normal and variant pelvic arterial anatomy is needed to ensure the safety and success of the procedure. The uterine artery classically arises as a first or second branch of the anterior division of the internal iliac artery and is usually dilated in the presence of a uterine fibroid tumor. Angiography is used for comprehensive pretreatment assessment of the pelvic arterial anatomy; for noninvasive evaluation, Doppler ultrasonography, contrast material-enhanced magnetic resonance (MR) imaging, and MR angiography also may be used. After the uterine artery is identified, selective catheterization should be performed distal to its cervicovaginal branch. For targeted embolization of the perifibroid arterial plexus, injection of particles with diameters larger than 500 mum is generally recommended. Excessive embolization may injure normal myometrium, ovaries, or fallopian tubes and lead to uterine necrosis or infection or to ovarian failure. Incomplete treatment or additional blood supply to the tumor (eg, via an ovarian artery) may result in clinical failure. The common postembolization angiographic end point is occlusion of the uterine arterial branches to the fibroid tumor while antegrade flow is maintained in the main uterine artery.