Ankle, knee, and elbow arthrography: 2022 survey of Society of Skeletal Radiology members.

OBJECTIVE: To determine the preferred ankle, knee, and elbow arthrography injection techniques for Society of Skeletal Radiology (SSR) members and whether more recently described techniques are gaining acceptance. We also sought to determine whether the concept of knowledge translation might explain differences between the preferred technique, year of fellowship graduation, and year the newer technique was described. MATERIALS AND METHODS: A 29-question survey was created in Qualtrics and submitted to current SSR members to determine if they perform knee, elbow, and ankle arthrography, and if so, the year of fellowship completion and preferred approaches. Survey respondents indicated the starting and ending needle tip positions for three knee, two elbow, and three ankle arthrography approaches using grids placed over provided frontal and lateral radiographs. RESULTS: Two hundred seventy-four SSR members (mean post-fellowship 13 years; range 0-38) completed the survey and performed fluoroscopic-guided knee (93%), elbow (95%), and ankle (75%) arthrography. Preferred approaches included the following: knee lateral subpatellar (43%), anterior (40%); elbow radiocapitellar (74%); ankle anterior/peritendon (70%), lateral mortise (24%). Preference of newer technique was related to fellowship graduation year and publication year for the ankle mortise (26% before, 42% after; p = 0.03) and posterior trans-triceps elbow articles (19% before, 33% after; p < 0.01). The anterior knee approach preference increased from 11% in 2008 to 40% (p ≤ 0.001). CONCLUSION: Nearly twice as many SSR members who graduated after the posterior trans-triceps and ankle mortise techniques were published prefer them for performing arthrography, possibly due to knowledge translation. The preference of the anterior knee arthrography approach has increased nearly fourfold since 2008.

Musculoskeletal glomus tumor: a review of 218 lesions in 176 patients.

OBJECTIVE: To review the spectrum of clinical and imaging features of glomus tumor involving the musculoskeletal system including the typically solitary forms as well as the rarer multifocal forms (glomuvenous malformation and glomangiomatosis). MATERIALS AND METHODS: A retrospective review of our institutional pathology database from 1996 to 2023 identified 176 patients with 218 confirmed glomus tumors. Primary imaging studies included MRI (125), radiographs (100), clinical/intraoperative photos (77), and ultrasound (36). Lesions were divided into two groups: those that are typically solitary involving specific anatomic areas (finger, toe, soft tissue, coccyx, and bone), and those that are multifocal (glomuvenous malformation and glomangiomatosis). RESULTS: The finger was the most frequently involved anatomic location for the classic (sporadic) glomus tumor occurring in 51% of patients, 77% of which were women, with the nail plate involved in more of the 75% of cases. Sporadic lesions involving the skin, subcutaneous adipose tissue, and deep soft tissue were termed "soft tissue," and were identified in 39% of patients, 90% of which were in the extremities and in men in 81% of cases. The multifocal syndromic forms of glomus disease occurred in younger individuals and involved less than 6% of the study group. Patients with glomuvenous malformation presented early with predominantly cutaneous involvement, while those with glomangiomatosis present later, often with both superficial and deep involvement, and a high rate of local tumor recurrence. CONCLUSION: While glomus tumor is generally uncommon, it frequently involves the musculoskeletal extremities. Knowledge of the spectrum of characteristic locations and appearances will facilitate definitive diagnosis.

CT-guided quadratus femoris injection for ischiofemoral impingement.

OBJECTIVES: To describe the technique, efficacy, and safety of CT-guided quadratus femoris injection with corticosteroid and local anesthetic for the treatment of ischiofemoral impingement in a series of cases at our institution. METHODS: Cases of CT-guided quadratus femoris injections from 2000 to 2021 were identified in the enterprise-wide electronic medical record of our institution. Patient charts and our institutional picture archiving and communication system (PACS) were searched for demographics, pain level on a 0-10 scale before and immediately following the procedure, procedure technique, and follow-up outcomes if available. RESULTS: There were 13 cases among 12 patients with clinical and imaging findings of ischiofemoral impingement included in this study. Of the 12 patients, 10 were female and two were male. There were eight posterior approaches and five posterolateral approaches. Of the 13 cases, 11 resulted in immediate pain reduction. The median reduction in pain score was four (average 3.46, range 0-8.5). There was no statistically significant difference in pain reduction between the posterior approach cases and the posterolateral approach cases. No cases reported immediate complications or increases in pain score. Of the 12 cases, seven resulted in at least 1 month of pain relief, three had subsequent surgeries, and three had no follow-up. CONCLUSION: CT-guided quadratus femoris injection is safe and effective for treating ischiofemoral impingement. Further and larger scale study is needed to fully delineate differences in technique effectiveness. KEY POINTS: • CT-guided quadratus femoris injection is safe and effective for treating ischiofemoral impingement. • We found no statistically significant difference in pain reduction between the posterior approach and the posterolateral approach.

The 2020 World Health Organization classification of bone tumors: what radiologists should know.

Improved understanding of tumor biology through molecular alteration and genetic advances has resulted in a number of major changes in the 2020 World Health Organization's (WHO) classification of bone tumors. These changes include the reclassification of the existing tumors and the introduction of several new entities. A new chapter on undifferentiated small round cell sarcomas of bone and soft tissue was added to classify Ewing sarcoma and the family of Ewing-like sarcomas, which share similar histologies but different molecular and clinical behaviors. Knowledge of the current classification of bone tumors is essential to ensure the appropriate recognition of the inherent biological potential of individual osseous lesions for optimal treatment, follow-up, and overall outcome. This article reviews the major changes to the 2020 WHO's classification of primary bone tumors and the pertinent imaging of selected tumors to highlight these changes.

Angiolipoma: a review of 778 lesions in 344 patients.

BACKGROUND: Angiolipomas are benign subcutaneous nodules that are commonly multifocal and easily overlooked by those not familiar with their appearance. The objective of this study was to identify the spectrum of the clinical and imaging features of this lesion, to include MR, CT, and US features. METHODS: A retrospective review of our institutional pathology database for biopsy-proven cases of angiolipoma between January 1, 2019, through December 31, 2021, was done. We identified 334 patients who underwent surgical resection of 788 individual lesions. MR imaging studies were available in 43 cases, CT in 39 cases, and ultrasound imaging in 72 cases. Clinical features (patient age, gender, surgical indication, number of lesions) were reviewed. Imaging feature analysis included the anatomic location, content of fat, vascularity, and modality-specific imaging features. RESULTS: All 778 angiolipomas were located in the subcutaneous tissues (median size, 2.4 cm, range 0.4-7.7 cm), with over 51% located in the upper extremity. The most common presentation was a symptomatic mass or slowly growing symptomatic mass. Imaging showed a subcutaneous lesion with a lobulated bean shape, which typically abutted the skin. Intralesional fat was identified in 85% of lesions on CT and MRI. Vessels were commonly seen on CT and MR, with enhancement best seen on MR. On US, lesions were heterogeneous and mildly hyperechoic, most often with no identifiable vascularity. CONCLUSION: Angiolipomas typically have characteristic imaging features. Awareness of this diagnosis and the spectrum of its imaging features is important and can facilitate a definitive diagnosis.

Periosteal chondrosarcoma: an unusual juxtacortical sarcoma.

Periosteal chondrosarcoma is a rare tumor. It can be difficult to diagnose radiographically and pathologically and can be confused with periosteal osteosarcoma; however, the treatment of these two lesions is quite different. Increased awareness of imaging features of this lesion, particularly those that can help differentiate it from other surface-based tumors, can help one recognize this entity. We report the case of a periosteal chondrosarcoma in a young woman, highlighting the diagnostic imaging features of this disease, and her treatment with a joint-sparing geometric resection of the distal femur, using patient-specific 3D-printed cutting guides and matched allograft reconstruction.

Calcific Tendinosis Reduces Diagnostic Performance of Magnetic Resonance Imaging in the Detection of Rotator Cuff Tears.

OBJECTIVE: This study aimed to investigate the effect of calcific tendinosis on the diagnosis of rotator cuff tears (RCTs) on magnetic resonance imaging (MRI) and magnetic resonance arthrography (MRA). MATERIALS AND METHODS: Calcific tendinosis was confirmed radiographically. Two musculoskeletal radiologists then retrospectively and independently reviewed the MRI/MRA examinations, with surgery or arthroscopy performed within 90 days of the MRI. Rotator cuffs were categorized as no tear, partial-thickness tear, and full-thickness tear. Partial-thickness tear/full-thickness tear groups were combined for analysis. RESULTS: Forty-eight MRI (mean age, 63.4 years; range, 37-83 years; female-to-male ratio, 29:19) and 7 MRA (mean age, 49.2 years; range, 25-60 years; female-to-male ratio, 4:3) patients were included. Reader 1 and reader 2 sensitivity/specificity values for RCTs on MRI were 95%/50% and 89%/30%, and the values on MRA were 100%/67% and 100%/100%, respectively. Overall agreement was present in 87% (48 of 55; κ = 0.55 [95% confidence interval, 0.26-0.85]). CONCLUSIONS: Magnetic resonance imaging has decreased specificity in diagnosing RCTs when calcific tendinosis is present. Magnetic resonance arthrography performed better in this population and could be considered.

Staging and Classification of Primary Musculoskeletal Bone and Soft-Tissue Tumors According to the 2020 WHO Update, From the AJR Special Series on Cancer Staging.

Staging of primary musculoskeletal bone and soft-tissue tumors is most commonly performed using the AJCC and the Enneking or Musculoskeletal Tumor Society (MSTS) staging systems. Radiologic imaging is integral in achieving adequate musculoskeletal neoplastic staging by defining lesion extent and identifying regional lymph node involvement and distant metastatic disease. Additional important features in surgical planning, though not distinct components of the staging systems, include cortical involvement, joint invasion, and neurovascular encasement; these features are optimally evaluated by MRI. In 2020, the WHO updated the classification of primary musculoskeletal tumors of soft tissue and bone. The update reflects the continued explosion in identification of novel gene alterations in many bone and soft-tissue neoplasms. This growth in gene alteration identification has resulted in newly designated lesions, reclassification of lesion categories, and improved specificity of diagnosis. Although radiologists do not need to have a comprehensive knowledge of the pathologic details, a broad working understanding of the most recent update is important to aid accurate and timely diagnosis given that histologic grading is a component of all staging systems. By using a multidisciplinary approach for primary musculoskeletal neoplasms involving colleagues in pathology, orthopedic oncology, radiation oncology, and medical oncology, radiologists may promote improved diagnosis, treatment, and outcomes.

Comparative Accuracy of 1.5T MRI, 3T MRI, and Static Ultrasound in Diagnosis of Small Gaps in Repaired Flexor Tendons: A Cadaveric Study.

PURPOSE: We hypothesized that magnetic resonance imaging (MRI) would more accurately diagnose small gaps (<6 mm) after flexor tendon repair than static ultrasound (US) and that suture artifact would negatively impair accuracy. METHODS: A laceration of the flexor digitorum profundus was created in 160 fresh-frozen cadaveric digits and randomized to either an intact repair (0-mm gap) or repairs using a locked 4-strand suture repair with either 4-0 Prolene, Ethibond, or and gaps of 2, 4,or 6 mm; or no suture in which 2-, 4-, or 6-mm gaps were created without a suture crossing the repair site. We performed 1.5T and 3T MRI and static US studies; gap widths were estimated by radiologists blinded to suture presence and true gap widths. RESULTS: The 1.5 and 3.0T MRI had a lower mean error than US for gap sizes 0 and 2 mm. All 3 modalities performed similarly for 4- and 6-mm gaps. Documentation of imaging artifact worsened error, and odds of seeing artifacts were 1.72 higher with MRI than with US. Suture did not worsen artifact nor impair accuracy for any of the 3 modalities. When no suture was used, all 3 modalities significantly overestimated the true gap. CONCLUSIONS: MRI is most accurate for small gaps less than 4 mm. Although all modalities overestimated gap sizes in specimens with a 0-mm gap (intact tendon repair), mean overestimation (<2 mm) was not clinically relevant. Ultrasound overestimated 2-mm gaps (clinically intact repairs), whereas MRIs did not. We recommend MRI for evaluation of gaps after flexor tendon repair. The 1.5T has slightly better sensitivity and specificity for distinguishing clinically intact (gap < 3 mm) from clinically impaired (gap > 3 mm) repairs than the 3T. CLINICAL RELEVANCE: Accurate diagnosis of intact repairs or small gaps (<3 mm) might prevent unnecessary exploration or allow modification of rehabilitation protocols. Diagnosis of clinically relevant gaps (3-6 mm) may allow for earlier revision surgery before significant tendon retraction and adhesions develop, possibly necessitating a staged reconstruction.

Desmoplastic Fibroblastoma: An Uncommon Tumor With a Relatively Characteristic MRI Appearance.

OBJECTIVE. We undertook this study to determine the radiologic features of desmo-plastic fibroblastoma. MATERIALS AND METHODS. We reviewed available radiologic images for 29 pathologically confirmed desmoplastic fibroblastomas, including images from MRI, radiography, ultrasound (US), and CT. RESULTS. The patient population included 14 women and 15 men (mean age, 60 years; range, 23-96 years). Typically, lesions were oval or lobulated and relatively small (mean, 5.6 cm). In 14 of the 22 cases that included patient histories, lesions had grown slowly, with two eventually causing pain. The remaining eight were discovered incidentally. All lesions involved or were below the deep fascia. Lesions were well-defined and associated with muscle (45%), deep fascia (28%), joint (21%), or tendon (7%). MR images were available in 26 cases; 14 included unenhanced and contrast-enhanced studies. On MRI imaging all lesions were well-defined and adjacent to dense connective tissue. On T1-weighted images, lesions showed varying amounts of low and intermediate signal intensity similar to that of tendon and skeletal muscle, respectively. On fluid-sensitive images, lesions were more heterogeneous, generally showing a wider spectrum of decreased to intermediate signal intensity. On contrast-enhanced MR images, enhancement was characteristically peripheral and septal with patchy areas of homogeneity. In the 10 cases with radiographs, images showed negative findings or a nonmineralized mass. The 10 available ultrasound studies showed mixed echogenicity. In eight patients, unenhanced CT showed lesions having attenuation similar to that of skeletal muscle. CONCLUSION. Desmoplastic fibroblastoma is an uncommon neoplasm with a relatively characteristic MRI appearance.

Skeletal Radiology: the year in review 2019.

In 2019, Skeletal Radiology published a total of 253 articles including 111 scientific articles, 36 review articles, 51 case reports, 16 Test-Yourself cases, 15 technical reports, as well as multiple browser notes, meeting abstracts, and meeting summaries. As we have done previously, in this review, we will highlight those articles that stimulated the most interest from our readers, as measured by their downloads, and those that stimulated other researchers and authors, as measured by their citations. The manuscripts highlighted herein were chosen from this list.

Postoperative Imaging of Sarcomas.

OBJECTIVE: The purpose of this article is to assist radiologists in developing an organized, systematic approach to imaging interpretation in the care of patients who have been surgically treated for sarcoma. CONCLUSION: Postoperative imaging interpretation of sarcoma can be complex and requires an organized, systematic approach that includes review of the patient's clinical and surgical history and pretreatment images to gain context for differentiating recurrence from time-dependent posttreatment changes.

Mosaic-pattern dedifferentiation in liposarcoma and chondrosarcoma: imaging features of an uncommon form of dedifferentiation.

The term "dedifferentiation" was classically used in sarcoma pathology to refer to tumors in which a high-grade, undifferentiated sarcoma, or a high-grade sarcoma showing heterologous differentiation, arises from a pre-existing neoplasm of borderline or low-grade malignancy. The best recognized examples of this include dedifferentiated liposarcoma, arising from atypical lipomatous tumor/well-differentiated liposarcoma, and dedifferentiated chondrosarcoma, arising from grade 1 hyaline chondrosarcoma of bone. In the overwhelming majority of cases, this dedifferentiated, high-grade sarcoma presents as a macroscopically visible mass, adjacent to and clearly distinct from the pre-existing low-grade lesion. It is less well appreciated that dedifferentiation may also occur in a so-called "mosaic pattern,' in which the high-grade component is intimately admixed with elements of the precursor lesion, forming only microscopically apparent foci. This mosaic or co-mingling pattern of dedifferentiation is also reflected in the MR imaging appearance. In contrast to the classic pattern of dedifferentiation in which there are two distinct juxtaposed masses with different signal intensities and enhancement patterns, such changes are not seen in mosaic dedifferentiation. The imaging features of this pattern of dedifferentiation have not been described. In this report we describe the imaging features of two patients with mosaic pattern dedifferentiation, one with liposarcoma and one with chondrosarcoma. In both cases the precursor lesion was correctly diagnosed by pre-biopsy imaging, but the presence of high-grade sarcoma was not recognized.

Skeletal Radiology: the year in review 2016.

A look back at Skeletal Radiology in 2016 reveals a sizable number of publications that significantly advanced the state of knowledge about diseases of the musculoskeletal system. This review summarizes the content of some of the most intriguing papers of the year.

Does Tibial Slope Affect Perception of Coronal Alignment on a Standing Anteroposterior Radiograph?

BACKGROUND: A standing anteroposterior (AP) radiograph is commonly used to evaluate coronal alignment following total knee arthroplasty (TKA). The impact of coronal alignment on TKA outcomes is controversial, perhaps due to variability in imaging and/or measurement technique. We sought to quantify the effect of image rotation and tibial slope on coronal alignment. METHODS: Using a standard extramedullary tibial alignment guide, 3 cadaver legs were cut to accept a tibial tray at 0°, 3°, and 7° of slope. A computed tomography scan of the entire tibia was obtained for each specimen to confirm neutral coronal alignment. Images were then obtained at progressive 10° intervals of internal and external rotation up to 40° maximum in each direction. Images were then randomized and 5 blinded TKA surgeons were asked to determine coronal alignment. Continuous data values were transformed to categorical data (neutral [0], valgus [L], and varus [R]). RESULTS: Each 10° interval of external rotation of a 7° sloped tibial cut (or relative internal rotation of a tibial component viewed in the AP plane) resulted in perception of an additional 0.75° of varus. CONCLUSION: The slope of the proximal tibia bone cut should be taken into account when measuring coronal alignment on a standing AP radiograph.

A Modified Lodwick-Madewell Grading System for the Evaluation of Lytic Bone Lesions.

OBJECTIVE: Lodwick's well-established grading system of lytic bone lesions has been widely used in predicting growth rate for lytic bone lesions. We applied a Modified Lodwick-Madewell Grading System as an alternative means to categorize lytic bone tumors into those with low, moderate, and high risks of malignancy. MATERIALS AND METHODS: A retrospective review of the radiographs of 183 bone lesions was performed. Cases were selected to include a broad range of benign and malignant tumors. Readers applied our Modified Lodwick-Madewell Grading System, and consensus was reached in all cases. This modified system consists of grade I, which is composed of grades IA and IB as listed in the Lodwick system; grade II, which is grade IC in the Lodwick system; and grade III, which is composed of IIIA (changing margination), IIB (moth-eaten and permeative patterns), and IIIC (radiographically occult). Grading was correlated with the final diagnosis. RESULTS: Of the 183 tumors, 81 were classified as grade I, 54 as grade II, and 48 as grade III. When correlating grade with pathology, we found that 76 of 81 (94%) grade I lesions were benign and 39 of 48 grade III lesions (81%) were malignant. A nearly equal number of grade II lesions proved to be benign (29/54; 54%) and malignant (28/54; 53%). CONCLUSION: By expanding Lodwick's grading system to include two additional patterns of disease described by Madewell and colleagues (changing margination and radiographically occult) and by reclassifying them into three distinct grades, we propose a modified system-the Modified Lodwick-Madewell Grading System. Application of this system shows correlation of tumor grade with tumor biologic activity and with risk of malignancy: Grade I lesions are usually benign, grade II lesions carry moderate risk of malignancy, and grade III lesions possess a high likelihood of malignancy.

Imaging of Soft-Tissue Musculoskeletal Masses: Fundamental Concepts.

Radiologic evaluation of musculoskeletal soft-tissue masses has changed dramatically with the continued improvements in imaging technology. The integration of advanced imaging has provided the radiologist with a wide range of assessment tools, but as with all powerful arsenals, selection and application of the appropriate imaging method can be problematic. Although the choices available for imaging evaluation of musculoskeletal masses have changed dramatically, the basic objectives of this assessment have remained constant: diagnosis and staging. The basic principles for evaluating musculoskeletal soft-tissue masses and achieving these objectives have not changed. This article addresses application of the current imaging methods to assessment of soft-tissue musculoskeletal masses, emphasizing fundamental concepts. We do not intend to provide a comprehensive review of imaging techniques, but rather to provide a useful review of the concepts needed to select the appropriate initial imaging method, magnetic resonance (MR) imaging field of view, MR imaging sequences, contrast material requirements, and rapid image acquisition techniques. We also address use of the new quantitative techniques of chemical shift and diffusion-weighted imaging. Finally, we review the current uses of computed tomography and ultrasonography. Although the choices available for imaging evaluation of musculoskeletal masses have changed dramatically within the past decade, appropriate application of the fundamental concepts of imaging will maximize the diagnostic utility of imaging examinations. ©RSNA, 2016.

Imaging characteristics of intravascular papillary endothelial hyperplasia.

PURPOSE: Intravascular papillary endothelial hyperplasia (IPEH) is a soft tissue, tumor-like, benign, reactive, vascular proliferation that, although not rare, is uncommonly imaged. We report the imaging findings of intravascular papillary endothelial hyperplasia in 13 patients, highlighting characteristic imaging features. MATERIALS AND METHODS: We retrospectively reviewed 13 patients with IPEH who had corresponding MR and/or ultrasound imaging. MR imaging studies were evaluated for lesion location, shape, size, signal intensity, signal heterogeneity, and enhancement. Ultrasound studies were assessed for lesion shape, size, echogenicity, heterogeneity, and vascularity. Demographic data, including patient age, gender, and clinical history were also reviewed. RESULTS: Most patients (11 of 13) presented with an enlarging mass. The age range was 10-72 years (mean 46) with ten females and three males. Eleven of the 13 lesions were primary IPEH without an associated preexisting vascular lesion. Ten of 13 lesions were in the superficial soft tissues, all of which were primary IPEH. Two of the three lesions in the deep tissues were secondary IPEH, arising within a preexisting vascular lesion. Lesions were small (mean 1.4 cm) and had a rounded shape. All of the primary lesions demonstrated high T2 signal peripherally and variable T2 signal centrally, with most demonstrating superficial location (91 %), peripheral enhancement (89 %) and associated dominant vessel (73 %). The five lesions evaluated by ultrasound were all hypoechoic with either scattered or peripheral vascularity on Doppler. CONCLUSIONS: Primary papillary endothelial hyperplasia is commonly seen in the superficial soft tissues when captured on imaging and has a characteristic imaging appearance.