Improved Resolution and Image Quality of Musculoskeletal Magnetic Resonance Imaging using Deep Learning-based Denoising Reconstruction: A Prospective Clinical Study.

OBJECTIVE: To prospectively evaluate a deep learning-based denoising reconstruction (DLR) for improved resolution and image quality in musculoskeletal (MSK) magnetic resonance imaging (MRI). METHODS: Images from 137 contrast-weighted sequences in 40 MSK patients were evaluated. Each sequence was performed twice, first with the routine parameters and reconstructed with a routine reconstruction filter (REF), then with higher resolution and reconstructed with DLR, and with three conventional reconstruction filters (NL2, GA43, GA53). The five reconstructions (REF, DLR, NL2, GA43, and GA53) were de-identified, randomized, and blindly reviewed by three MSK radiologists using eight scoring criteria and a forced ranking. Quantitative SNR, CNR, and structure's full width at half maximum (FWHM) for resolution assessment were measured and compared. To account for repeated measures, Generalized Estimating Equations (GEE) with Bonferroni adjustment was used to compare the reader's scores, SNR, CNR, and FWHM between DLR vs. NL2, GA43, GA53, and REF. RESULTS: Compared to the routine REF images, the resolution was improved by 47.61% with DLR from 0.39 ± 0.15 mm2 to 0.20 ± 0.06 mm2 (p < 0.001). Per-sequence average scan time was shortened by 7.93% with DLR from 165.58 ± 21.86 s to 152.45 ± 25.65 s (p < 0.001). Based on the average scores, DLR images were rated significantly higher in all image quality criteria and the forced ranking (p < 0.001). CONCLUSION: This prospective clinical evaluation demonstrated that DLR allows approximately two times finer resolution and improved image quality compared to the standard-of-care images.

Imaging Coccygeal Trauma and Coccydynia.

The coccygeal region has complex anatomy, much of which may contribute to or be the cause of coccyx region pain (coccydynia). This anatomy is well depicted at imaging, and management is often dictated by what structures are involved. Coccydynia is a common condition that is known to be difficult to evaluate and treat. However, imaging can aid in determining potential causes of pain to help guide management. Commonly, coccydynia (coccygodynia) occurs after trauma and appears with normal imaging features at static neutral radiography, but dynamic imaging with standing and seated lateral radiography may reveal pathologic coccygeal motion that is predictive of pain. In addition, several findings seen at cross-sectional imaging in patients with coccydynia can point to a source of pain that may be subtle and easily overlooked. Radiology can also offer a role in management of coccygeal region pain with image-guided pain management procedures such as ganglion impar block. In addition to mechanical coccyx pain, a host of other conditions involving the sacrococcygeal region may cause coccydynia, which are well depicted at imaging. These include neoplasm, infection, crystal deposition, and cystic formations such as pilonidal cyst. The authors review a variety of coccydynia causes, their respective imaging features, and common management strategies.©RSNA, 2020.

Adhesive capsulitis: review of imaging findings, pathophysiology, clinical presentation, and treatment options.

Adhesive capsulitis, commonly referred to as "frozen shoulder," is a debilitating condition characterized by progressive pain and limited range of motion about the glenohumeral joint. It is a condition that typically affects middle-aged women, with some evidence for an association with endocrinological, rheumatological, and autoimmune disease states. Management tends to be conservative, as most cases resolve spontaneously, although a subset of patients progress to permanent disability. Conventional arthrographic findings include decreased capsular distension and volume of the axillary recess when compared with the normal glenohumeral joint, in spite of the fact that fluoroscopic visualization alone is rarely carried out today in favor of magnetic resonance imaging (MRI). MRI and MR arthrography (MRA) have, in recent years, allowed for the visualization of several characteristic signs seen with this condition, including thickening of the coracohumeral ligament, axillary pouch and rotator interval joint capsule, in addition to the obliteration of the subcoracoid fat triangle. Additional findings include T2 signal hyperintensity and post-contrast enhancement of the joint capsule. Similar changes are observable on ultrasound. However, the use of ultrasound is most clearly established for image-guided injection therapy. More aggressive therapies, including arthroscopic release and open capsulotomy, may be indicated for refractory disease, with arthroscopic procedures favored because of their less invasive nature and relatively high success rate.

Coracoid process fractures: anatomy, injury patterns, multimodality imaging, and approach to management.

The coracoid process of the scapula is in close proximity to major neurovascular structures, including the brachial plexus and the axillary artery and vein. In addition, it serves as a major site of attachment for multiple tendons and ligaments about the shoulder. Isolated coracoid fractures are rare; however, they can be easily overlooked on routine shoulder radiographs. Importantly, when these fractures go undiagnosed, they are at high risk for nonunion. In this paper, we will review the relevant anatomy of the coracoid process, classification schemes for coracoid fractures, mechanisms of injury how these fractures typically present, multimodality imaging findings, and associated injuries. Finally, we will briefly discuss the clinical management of these fractures.

Intra-articular tongue-type fractures of the calcaneus: anatomy, injury patterns, and an approach to management.

Intra-articular tongue-type fractures may develop skin breakdown and often require urgent surgical reduction and fixation. Recognition of the imaging findings, accurate interpretation, and timely communication may prevent devastating clinical outcomes including soft tissue coverage procedures and amputation. This article reviews the anatomy of the calcaneus, as well as the clinical presentation and imaging findings of intra-articular tongue-type fractures. Imaging interpretation and clinical management of these fractures are discussed.

Detection of Traumatic Pediatric Elbow Joint Effusion Using a Deep Convolutional Neural Network.

OBJECTIVE: The purpose of this study is to determine whether a deep convolutional neural network (DCNN) trained on a dataset of limited size can accurately diagnose traumatic pediatric elbow effusion on lateral radiographs. MATERIALS AND METHODS: A total of 901 lateral elbow radiographs from 882 pediatric patients who presented to the emergency department with upper extremity trauma were divided into a training set (657 images), a validation set (115 images), and an independent test set (129 images). The training set was used to train DCNNs of varying depth, architecture, and parameter initialization, some trained from randomly initialized parameter weights and others trained using parameter weights derived from pretraining on an ImageNet dataset. Hyperparameters were optimized using the validation set, and the DCNN with the highest ROC AUC on the validation set was selected for further performance testing on the test set. RESULTS: The final trained DCNN model had an ROC AUC of 0.985 (95% CI, 0.966-1.000) on the validation set and 0.943 (95% CI, 0.884-1.000) on the test set. On the test set, sensitivity was 0.909 (95% CI, 0.788-1.000), specificity was 0.906 (95% CI, 0.844-0.958), and accuracy was 0.907 (95% CI, 0.843-0.951). CONCLUSION: Accurate diagnosis of traumatic pediatric elbow joint effusion can be achieved using a DCNN.

Isolated greater tuberosity fractures of the proximal humerus: anatomy, injury patterns, multimodality imaging, and approach to management.

The greater tuberosity is an important anatomic structure and its integrity is important for shoulder abduction and external rotation. Isolated fractures of the greater tuberosity are often subtle and may not be detected on initial radiographs. Clinically, these patients display symptoms which mimic a full thickness rotator cuff tear. It is important to differentiate these two entities, as their treatment is different (typically nonsurgical management for minimally displaced fractures versus rotator cuff repair for acute full thickness rotator cuff tears). When greater tuberosity fractures are significantly displaced and allowed to heal without anatomic reduction, they can lead to impingement. This article will review greater tuberosity anatomy and function, as well as the clinical presentation and multimodality imaging findings of greater tuberosity fractures. Imaging optimization, pitfalls, and clinical management of these fractures will also be discussed.

Critical role for inflammasome-independent IL-1ß production in osteomyelitis.

The immune system plays an important role in the pathophysiology of many acute and chronic bone disorders, but the specific inflammatory networks that regulate individual bone disorders remain to be elucidated. Here, we characterized the osteoimmunological underpinnings of osteolytic bone disease in Pstpip2(cmo) mice. These mice carry a homozygous L98P missense mutation in the Pombe Cdc15 homology family phosphatase PSTPIP2 that is responsible for the development of a persistent autoinflammatory disease resembling chronic recurrent multifocal osteomyelitis in humans. We found that improper regulation of IL-1ß production resulted in secondary induction of inflammatory cytokines, inflammatory cell infiltration in the bone, and unremitting bone inflammation. Aberrant Il1ß expression precedes the development of osteolytic damage in young Pstpip2(cmo) mice, and genetic deletion of Il1r and Il1ß, but not Il1α, rescued osteolytic bone disease in mutant mice. Intriguingly, caspase-1 and nucleotide-binding oligomerization domain (NOD)-like receptor family, pyrin domain containing 3 activation in the inflammasome complex were dispensable for Pstpip2(cmo)-mediated bone disease. Thus, our findings establish a critical role for inflammasome-independent production of IL-1ß in osteolytic bone disease and identify PSTPIP2 as a negative regulator of caspase-1-autonomous IL-1ß production.

An approach to anisocoria.

PURPOSE OF REVIEW: Anisocoria is a finding seen on a daily basis in nearly every eye clinic. Although often benign, it can also represent the sole sign of a life-threatening disease making an up-to-date understanding of pathophysiology and diagnosis essential for anyone practicing medicine. RECENT FINDINGS: Many aspects of the traditional approach to anisocoria still hold true today, but advancements in imaging technology and changing trends in pharmacologic diagnosis and localization have led many to rethink that approach. In addition, the differential diagnosis for anisocoria continuously expands with identification and improved understanding of causal disease processes. SUMMARY: The present article discusses an approach to the classic anisocoria diagnostic algorithm modified by current knowledge from the most recent literature.

Estimating greenhouse gas emissions at the soil-atmosphere interface in forested watersheds of the US Northeast.

Although anthropogenic emissions of greenhouse gases (GHG: CO2, CH4, N2O) are unequivocally tied to climate change, natural systems such as forests have the potential to affect GHG concentration in the atmosphere. Our study reports GHG emissions as CO2, CH4, N2O, and CO2eq fluxes across a range of landscape hydrogeomorphic classes (wetlands, riparian areas, lower hillslopes, upper hillslopes) in a forested watershed of the Northeastern USA and assesses the usability of the topographic wetness index (TWI) as a tool to identify distinct landscape geomorphic classes to aid in the development of GHG budgets at the soil atmosphere interface at the watershed scale. Wetlands were hot spots of GHG production (in CO2eq) in the landscape owing to large CH4 emission. However, on an areal basis, the lower hillslope class had the greatest influence on the net watershed CO2eq efflux, mainly because it encompassed the largest proportion of the study watershed (54 %) and had high CO2 fluxes relative to other land classes. On an annual basis, summer, fall, winter, and spring accounted for 40, 27, 9, and 24 % of total CO2eq emissions, respectively. When compared to other approaches (e.g., random or systematic sampling design), the TWI landscape classification method was successful in identifying dominant landscape hydrogeomorphic classes and offered the possibility of systematically accounting for small areas of the watershed (e.g., wetlands) that have a disproportionate effect on total GHG emissions. Overall, results indicate that soil CO2eq efflux in the Archer Creek Watershed may exceed C uptake by live trees under current conditions.

Ultrasound Fusion: Applications in Musculoskeletal Imaging.

Ultrasound fusion is an established technique that pairs real time B-scan ultrasound (US) with other forms of cross-sectional imaging, including computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). Each of these imaging modalities has distinct advantages. CT provides superior anatomic resolution, with improved imaging of bone and calcified structures; MRI has superior contrast resolution; and PET provides physiologic information, identifying processes that are metabolically active (i.e., tumor, inflammatory conditions). However, these modalities are static. A key highlight of ultrasound is its capability of dynamic, real-time scanning. The ability to pair CT, MRI or PET with ultrasound can have significant advantages, both in diagnostic evaluation and when performing difficult or challenging image-guided interventions. Percutaneous interventions using ultrasound fusion have been described in the abdominal imaging literature; however, there have been very few musculoskeletal applications detailed in the literature. The purpose of this article is to review the basic concepts of real-time ultrasound fusion, and to detail, through the use of multiple case examples, its potential use as a safe and effective method for performing image-guided musculoskeletal interventions.

Current and Future Advanced Imaging Modalities for the Diagnosis of Early Osteoarthritis of the Hip.

Hip osteoarthritis (OA) can be idiopathic or develop secondary to structural joint abnormalities of the hip joint (alteration of normal anatomy) and/or due to a systemic condition with joint involvement. Early osteoarthritic changes to the hip can be completely asymptomatic or may cause the development hip symptomatology without evidence of OA on radiographs. Delaying the progression of hip OA is critical due to the significant impact of this condition on the patient's quality of life. Pre-OA of the hip is a newly established term that is often described as the development of signs and symptoms of degenerative hip disease but no radiographic evidence of OA. Advanced imaging methods can help to diagnose pre-OA of the hip in patients with hip pain and normal radiographs or aid in the surveillance of asymptomatic patients with an underlying hip diagnosis that is known to increase the risk of early OA of the hip. These methods include the delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC), quantitative magnetic resonance imaging (qMRI- T1rho, T2, and T2* relaxation time mapping), 7-Tesla MRI, computed tomography (CT), and optical coherence tomography (OCT). dGEMRIC proved to be a reliable and accurate modality though it is limited by the significant time necessary for contrast washout between scans. This disadvantage is potentially overcome by T2 weighted MRIs, which do not require contrast. 7-Tesla MRI is a promising development for enhanced imaging resolution compared to 1.5 and 3T MRIs. This technique does require additional optimization and development prior to widespread clinical use. The purpose of this review was to summarize the results of translational and clinical studies investigating the utilization of the above-mentioned imaging modalities to diagnose hip pre-OA, with special focus on recent research evaluating their implementation into clinical practice.

Chronic tophaceous gout causing lumbar spinal stenosis.

Gout is a common cause of inflammatory arthritis, typically affecting the joints of the appendicular skeleton. In this report, we present the relatively less common scenario of chronic tophaceous gout affecting the lumbar spine and pelvis, complicated by compressive neuropathy, and notable for its advanced initial presentation in a young patient. We review the pathophysiology underlying gout and discuss its clinical and laboratory presentation. We also use our case as an example to present the radiographic, CT, and MR imaging features of gout affecting the lumbar spine, which can often present a diagnostic dilemma. Finally, we discuss therapeutic options for gout resulting in spinal canal compromise, which include interventions not commonly performed for gout elsewhere in the body.

Illustrative review of knee meniscal tear patterns, repair and replacement options, and imaging evaluation.

This review article aims to reinforce anatomical concepts about meniscal tears while linking associated treatment options. The main teaching points start with the basic meniscal anatomy and key differences between the medial and lateral menisci. Subsequently, various meniscal tear patterns along with their associated history and physical exam findings will be discussed with corresponding illustrations and MR images. Additional discussion will involve the different surgical repair techniques (with arthroscopic correlates), their indications with pertinent imaging findings, imaging related to previous meniscal tear repairs, and novel surgical techniques. Lastly, keys to evaluating for retear with an emphasis on MRI arthrogram findings will be reviewed. While each of these topics is not discussed in totality, the key points of the review article will enforce key concepts and help radiologists evaluate the menisci on imaging.

Compressed Sensing MR Imaging (CS-MRI) of the Knee: Assessment of Quality, Inter-reader Agreement, and Acquisition Time.

We compared 3 Tesla (3T) compressed sensing (CS)-MRI of different pulse sequences with various acceleration factors to standard fast spin-echo (FSE) sequences in terms of time, quality, and inter-reader agreement. Each sequence was qualitatively ranked and then qualitatively scored for blurring, artifact, low contrast detection, noise pattern, signal-to-noise ratio, and overall quality. The CS-MRI sequences demonstrated very good overall quality compared with routine FSE sequences with overall good inter-reader agreement.

Prayer's fracture: rare cases of knee insufficiency fracture in non-weight-bearing femoral condyle.

Insufficiency fractures are a relatively common sub-type of stress fractures and occur as a result of decreased bone resistance due to underlying conditions such as osteoporosis. Insufficiency fractures of the knee most commonly occur at the central weight-bearing zone of the medial femoral condyle. We present five unusual cases of insufficiency fractures occurring at the posterior non-weight-bearing zone of condyles. After investigating commonalities between these patients, we discovered that all of these patients performed the daily practice of prayer rituals that include high knee flexion. We have chosen to coin this type of fracture a "Prayer's fracture". Considering the mechanics of high knee flexion, transient changes in the weight-bearing zone of knee explain the unusual location of this fracture. We describe these cases, the characteristic imaging appearance, and the probable biomechanics that we believe predispose patients to this type of injury.

MR imaging of cartilage repair surgery of the knee.

Articular cartilage is a complex tissue with unique properties that are essential for normal joint function. Many processes can result in cartilage injury, ranging from acute trauma to degenerative processes. Articular cartilage lacks vascularity, and therefore most chondral defects do not heal spontaneously and may require surgical repair. A variety of cartilage repair techniques have been developed and include bone marrow stimulation (microfracture), osteochondral autograft transfer system (OATS) or osteochondral allograft transplantation, autologous chondrocyte implantation (ACI), matrix-assisted chondrocyte implantation (MACI), and other newer processed allograft cartilage techniques. Although arthroscopy has long been considered as the gold standard for evaluation of cartilage after cartilage repair, magnetic resonance (MR) imaging is a non-invasive method to assess the repair site and can be scored using Magnetic resonance Observation of Cartilage Repair Tissue (MOCART). MR also provides additional evaluation of the subchondral bone and for other potential causes of knee pain or internal derangement. Conventional MR can be used to evaluate the status of cartilage repair and potential complications. Compositional MR sequences can provide supplementary information about the biochemical contents of the reparative tissue. This article reviews the various types of cartilage repair surgeries and their postoperative MR imaging appearances.

Bucket-Handle Tear of the Medial Meniscus in a 2-Year-Old Child.

Bucket-handle meniscal tears are extremely rare injuries in the pediatric population. Given the known sequelae of meniscal tears and the development of osteoarthritis, early diagnosis and treatment of pediatric meniscal tears are essential. The communication barrier between physicians and pediatric patients, however, creates difficulties in making the correct diagnosis of meniscal pathology. Providers should have a low threshold for obtaining further confirmatory advanced imaging if patients present with prolonged knee pain and swelling, with associated locking mechanical symptoms. Good clinical outcomes following meniscal repair have been observed, likely a result of the increased residual vascularity found within pediatric menisci. The youngest reported case of an isolated traumatic bucket-handle medial meniscal tear is examined in this article. A 2-year-old girl presented with right knee pain after a heavy object fell onto the knee several weeks earlier. On examination, the patient walked with a limp but lacked full range of active knee motion. The McMurray test elicited pain without a mechanical or palpable click. After the patient continued to exhibit limitations following conservative management, magnetic resonance imaging of the right knee was obtained, which showed a bucket-handle tear of the right medial meniscus. The patient subsequently underwent meniscal repair and, on recovery, was able to regain normal functioning of the right knee without limitations. [Orthopedics. 2018; 41(4):e580-e582.].