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.

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.

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.

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.

Musculoskeletal Sarcoma: Update on Imaging of the Post-treatment Patient.

Post-treatment imaging of musculoskeletal sarcoma remains challenging, but newer imaging techniques are improving our ability to recognize both local and distant recurrence and accurately distinguish local recurrence from post-treatment change. We review recent advances in dynamic contrast-enhanced magnetic resonance imaging, diffusion-weighted magnetic resonance imaging with apparent diffusion coefficient mapping and positron emission tomography/computed tomography in the post-treatment follow-up of musculoskeletal sarcoma. We also describe our multidisciplinary sarcoma team approach to patient care and the essential role of the radiologist in the clinical follow-up scheme.

Synovial sarcoma presenting as an avascular mass: radiologic-pathologic correlation.

Synovial sarcoma is a well-recognized soft tissue malignancy that typically arises in young adults. It is now generally accepted that its origin is likely from undifferentiated mesenchymal tissue with variable epithelial differentiation and a highly specific chromosomal translocation in more than 95% of cases. The lesion typically presents as a slow-growing soft tissue mass, with MR imaging demonstrating a heterogeneous mass with variable amounts of low-, intermediate- and high-signal intensity on fluid-sensitive images and prominent heterogeneous enhancement, reflecting its vascularity. The relative hypervascularity of synovial sarcoma has been well established and is reflected in its enhancement on MR imaging studies. Contrast enhancement on MR imaging has been long used as a marker for tissue vascularization and perfusion, with malignant lesions generally being more vascular and enhancing more rapidly. We recently encountered a patient with a high-grade synovial sarcoma with no discernable necrosis and no vascularity on contrast-enhanced MR images with the subtraction technique, despite enhancement in adjacent regional metastatic lymph nodes. The pathologic basis for this unusual imaging appearance was a paucity of small-caliber vessels within the sarcoma due to extensive hyalinization of the mass.

Leukocyte esterase analysis in the diagnosis of joint infection: can we make a diagnosis using a simple urine dipstick?

PURPOSE: Analysis of joint fluid remains a key factor in the diagnosis of periprosthetic infection. Recent reports have shown that neutrophils in infected joint fluid release esterase, an enzyme that is a reliable marker for infection. Testing for leukocyte esterase is routinely done in the analysis of urine for the presence of urinary tract infection, by a simple "dipstick" method. We report our experience with this technique in the evaluation of patients suspected of having septic arthritis or periprosthetic joint infection (PJI) by comparing results of leukocyte esterase positivity with confirmed joint infection as defined by the American Academy of Orthopaedic Surgeons (AAOS). MATERIALS AND METHODS: We retrospectively reviewed leukocyte esterase test results performed on synovial fluid aspirated from 57 patients with prosthetic (52) and native (5) joints. Patients either presented with unexplained painful arthroplasties, routine testing of PROSTALAC (PROSthesis with Antibiotic-Loaded Acrylic Cement) orthopedic implants, or clinical suspicion of periprosthetic infection or septic arthritis. Synovial fluid was percutaneously aspirated using a standard technique. The patient age range was 31-91 years with a mean age of 69.1 years, consisting of 30 women (52.6 %) and 27 men (47.4 %). The "gold standard" for the presence or absence of infection at our institution and in the study group was based on the most recent recommendations of the AAOS. Positive culture remained the "gold standard" for native joint infection. RESULTS: Of the total 57 joints aspirated and included in the study, 20 (35.1 %) were read as positive (2+) on the leukocyte test strip and 37 (64.9 %) were read as negative (negative, trace, or 1+). PJI was diagnosed in 19 patients and native joint septic arthritis was identified in one patient. Sensitivities were excellent at 100 % with no false negatives in the entire cohort. There was one false positive in the periprosthetic group yielding a specificity, positive predictive value and negative predictive value of 97, 95, and 100 %, respectively. The results for the native joints showed markedly less specificity and positive predictive value at 50 and 33 %; however, its negative predictive value remained at 100 %. CONCLUSIONS: Our test results confirm that the leukocyte esterase test can accurately detect PJI and that it can be used as a part of the traditional PJI workup. In the assessment of native joints, its high negative predictive value suggests that it is a valuable tool in excluding native joint septic arthritis.

From the radiologic pathology archives imaging of osteonecrosis: radiologic-pathologic correlation.

Osteonecrosis is common and represents loss of blood supply to a region of bone. Common sites affected include the femoral head, humeral head, knee, femoral/tibial metadiaphysis, scaphoid, lunate, and talus. Symptomatic femoral head osteonecrosis accounts for 10,000-20,000 new cases annually in the United States. In contradistinction, metadiaphyseal osteonecrosis is often occult and asymptomatic. There are numerous causes of osteonecrosis most commonly related to trauma, corticosteroids, and idiopathic. Imaging of osteonecrosis is frequently diagnostic with a serpentine rim of sclerosis on radiographs, photopenia in early disease at bone scintigraphy, and maintained yellow marrow at MR imaging with a serpentine rim of high signal intensity (double-line sign) on images obtained with long repetition time sequences. These radiologic features correspond to the underlying pathology of osseous response to wall off the osteonecrotic process and attempts at repair with vascularized granulation tissue at the reactive interface. The long-term clinical importance of epiphyseal osteonecrosis is almost exclusively based on the likelihood of overlying articular collapse. MR imaging is generally considered the most sensitive and specific imaging modality both for early diagnosis and identifying features that increase the possibility of this complication. Treatment subsequent to articular collapse and development of secondary osteoarthritis typically requires reconstructive surgery. Malignant transformation of osteonecrosis is rare and almost exclusively associated with metadiaphyseal lesions. Imaging features of this dire sequela include aggressive bone destruction about the lesion margin, cortical involvement, and an associated soft-tissue mass. Recognizing the appearance of osteonecrosis, which reflects the underlying pathology, improves radiologic assessment and is important to guide optimal patient management.

Accuracy of chemical shift MR imaging in diagnosing indeterminate bone marrow lesions in the pelvis: review of a single institution's experience.

OBJECTIVE: To re-assess the accuracy of chemical shift imaging in diagnosing indeterminate bone marrow lesions as benign or malignant. MATERIALS AND METHODS: We retrospectively reviewed our experience with MR imaging of the pelvis to assess the accuracy of chemical shift imaging in distinguishing benign from malignant bone lesions. Two musculoskeletal radiologists retrospectively reviewed all osseous lesions biopsied since 2006, when chemical shift imaging was added to our routine pelvic imaging protocol. Study inclusion criteria required (1) MR imaging of an indeterminate bone marrow lesion about the pelvis and (2) subsequent histologic confirmation. The study group included 50 patients (29 male, 21 female) with an average age of 67 years (range, 41-89 years). MR imaging results were evaluated using biopsy results as the "gold standard." RESULTS: There were 27 malignant and 23 benign lesions. Chemical shift imaging using an opposed-phase signal loss criteria of less than 20 % to indicate a malignant lesion, correctly diagnosed 27/27 malignant lesions and 14/23 benign lesions, yielding a 100 % sensitivity, 61 % specificity, 75 % PPV, 100 % NPV, and 82 % accuracy. The area under the receiver operator characteristic (ROC) curve was 0.88. The inter-rater and intra-rater agreement K values were both 1.0. CONCLUSIONS: Chemical shift imaging is a useful adjunct MR technique to characterize focal and diffuse marrow abnormalities on routine non-contrast pelvic imaging. It is highly sensitive in identifying malignant disease. Despite its lower specificity, the need for biopsy could be eliminated in more than 60 % of patients with benign disease.