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Magnetic resonance imaging (MRI) of skeletal muscle is routinely performed using morphological sequences to acquire anatomical information. Recently, there is an increasing interest in applying advanced MRI techniques that provide pathophysiologic information for skeletal muscle evaluation to complement standard morphologic information. Among these advanced techniques, diffusion tensor imaging (DTI) has emerged as a potential tool to explore muscle microstructure. DTI can noninvasively assess the movement of water molecules in well-organized tissues with anisotropic diffusion, such as skeletal muscle. The acquisition of DTI studies for skeletal muscle assessment requires specific technical adjustments. Besides, knowledge of DTI physical basis and skeletal muscle physiopathology facilitates the evaluation of this advanced sequence and both image and parameter interpretation. Parameters derived from DTI provide a quantitative assessment of muscle microstructure with potential to become imaging biomarkers of normal and pathological skeletal muscle. KEY POINTS: • Diffusion tensor imaging (DTI) allows to evaluate the three-dimensional movement of water molecules inside biological tissues. • The skeletal muscle structure makes it suitable for being evaluated with DTI. • Several technical adjustments have to be considered for obtaining robust and reproducible DTI studies for skeletal muscle assessment, minimizing potential artifacts.

Plexopathy may be caused by diverse pathologies, including trauma, nerve entrapment, neoplasm, inflammation, infection, autoimmune disease, hereditary disease, and idiopathic etiologies. For patients presenting with brachial or lumbosacral plexopathy, dedicated plexus MRI is the most appropriate initial imaging modality for all clinical scenarios and can identify processes both intrinsic and extrinsic to the nerves. Other imaging tests may be appropriate for initial imaging depending on the clinical scenario. This document addresses initial imaging strategies for brachial and lumbosacral plexopathy in the following clinical situations: nontraumatic plexopathy with no known malignancy, traumatic plexopathy (not perinatal), and plexopathy occurring in the context of a known malignancy or posttreatment syndrome. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Inflammatory back pain is a hallmark feature of axial spondyloarthritis, a heterogeneous group of inflammatory disorders which affects the sacroiliac joints and spine. Imaging plays a key role in diagnosis of this disease and in facilitating appropriate treatment. This document provides evidence-based recommendations on the appropriate use of imaging studies during multiple stages of the clinical evaluation of patients with suspected or known axial spondyloarthritis. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Whole-Body MRI (WB-MRI) is increasing in clinical acceptance and utilization for a range of indications. WB-MRI is currently an established screening tool for children and adults at high risk of developing malignancy, with the strongest supporting evidence in patients with Li-Fraumeni syndrome. WB-MRI has also been implemented in professional society guidelines for staging patients with certain malignancies including multiple myeloma, as well as proposed as a technique to screen for metastatic disease in patients with visceral malignancies including prostate cancer and breast cancer. Emerging data support the utility of WB-MRI in children with malignancies such as Ewing sarcoma, in adults with myxoid liposarcoma, and in pregnant patients with occult or newly detected malignancy. WB-MRI can further help evaluate disease extent and treatment response in patients with nononcologic conditions such as chronic non-bacterial osteomyelitis, myopathy, inflammatory arthritis, and fever of unknown origin. This AJR Expert Panel Narrative Review summarizes available evidence and recommendations supporting the clinical applications of WB-MRI. The article also highlights limitations, barriers, and controversies associated with utilization of WB-MRI in routine clinical practice.

To determine the frequency of non-diagnostic and discordant results from bone and soft tissue biopsies performed at our institution over a 3-year period and to investigate whether implementation of a weekly musculoskeletal radiology-pathology correlation conference decreased the time to appropriate patient management in cases of discordance. Consecutive image-guided core needle biopsy results obtained over a 12 month period of time were reviewed in a retrospective fashion. Following implementation of the correlation conference, subsequent consecutive image-guided core needle biopsy results obtained over a 26 month period of time were reviewed in a prospective fashion. For non-diagnostic and discordant cases, the time in days from date of availability of the biopsy result to date of documentation of a specific follow-up action plan was recorded. Diagnostic yield was 96.5% and 94.9% for the retrospective and prospective periods, respectively. There were four discordant results in the retrospective cohort (1.7%) and seven discordant results in the prospective cohort (2.1%). Following implementation of the weekly correlation conference, there was significant decrease (p

Purpose The American Academy of Orthopaedic Surgeons and the American Society for Surgery of the Hand developed candidate quality measures for potential inclusion in the Merit-Based Incentive Program and National Quality Forum in the hope that hand surgeons could report specialty-specific data. The following measures regarding the management of carpal tunnel syndrome (CTS) were developed using a Delphi consensus process: (1) use of magnetic resonance imaging (MRI) for diagnosis of CTS, (2) use of adjunctive surgical procedures during carpal tunnel release (CTR), and (3) use of formal occupational and/or physical therapy after CTR. This study simulated attempts to identify outlier regions in an insurance claims database, which is an important step in establishing feasibility of these measures. Methods Using the Truven Health MarketScan, we identified 643,357 patients who were given a diagnosis of CTS between 2012 and 2014. We reported the percentage of metropolitan statistical areas (MSA) with one or more claims for MRI within 90 days of CTS diagnosis, one or more adjunctive surgical procedures, and one or more formal referrals for physical and/or occupational therapy within 6 weeks of CTR, and we calculated the rate of use for each of these diagnostic or treatment modalities. In addition, we report the precision ratio (signal to noise), SD, and 95% confidence interval. Results A high percentage of patients given a diagnosis of CTS did not have MRI (99%), and the precision ratio was considered high (0.99). Over 30% of all observed MSAs had at least one claim for MRI as a diagnostic modality in CTS. Most patients (98%) did not have adjunctive surgical procedures. For the observed years, over 28% of MSAs had at least one insurance claim for an adjunctive procedure. A total of 86% of patients did not receive formal occupational or physical therapy after CTR. In addition, 92% of MSAs had at least one claim for therapy. The precision ratio was considered high (approximately 0.85). Conclusions There is regional variation in the utilization rate of diagnostic MRI for CTS, adjunctive surgical procedures, and formal referral for physical and occupational therapy. For the proposed quality measures, outlier regions can be detected in insurance claims data. Clinical relevance Use of MRI in diagnosis, adjunctive surgical procedures, and formal therapy after surgery are feasible quality measures for the Merit-Based Incentive Program and National Quality Forum.

To evaluate musculoskeletal (MSK) radiologist whole-body magnetic resonance imaging (WBMRI) practice patterns in an effort to better understand current MSK clinical utilization and the need for standardized coding. A 12-question survey was created in Survey Monkey®. The survey was e-mailed to Society of Skeletal Radiology (SSR) members on September 19, 2018. The survey included questions on SSR member demographics and on their experience with WBMRI. One hundred sixty-four of 1454 (11%) SSR members responded to the survey. A minority (32%; n = 52/164) of respondents reported that their institutions routinely perform WBMRI. The most common indication was multiple myeloma (78%, n = 51/65). The most commonly utilized sequences were coronal short tau inversion recovery (STIR) (79%, n = 52/66) and coronal T1 without fat saturation (73%, n = 48/66). A large proportion of respondents (48%, n = 31/64) did not know the code used for billing WBMRI at their institutions. Of the remaining respondents, 23% (n = 15/64) reported use of the bone marrow MRI code, 16% (n = 10/64) the chest/abdomen/pelvis combination code, and 9% (n = 6/64) the unlisted MRI procedure code. There is variation in who is responsible for the protocol and interpretation of WBMRI, as well as how the exam is performed and how the exam is coded, which raise barriers to broad implementation. Recent WBMRI guidelines for multiple myeloma and prostate cancer can mitigate many of these barriers, but they do not address the coding and reimbursement challenges. Collaborative multi-society development of a new CPT® code for WBMRI may be a worthwhile endeavor.

Although primary bone tumors are relatively uncommon, appropriate imaging evaluation is essential when they are suspected or incidentally detected. In almost all cases, radiographs are the most appropriate initial imaging study for screening and characterization of primary bone tumors. Radiographs often provide sufficient information for diagnosis and to guide the treating clinician. However, when conventional radiographs alone are inadequate, they still often guide the selection of the most appropriate next step for advanced imaging. MRI and CT are typically the most appropriate next step. MRI provides excellent soft-tissue contrast allowing for evaluation of the tissue composition (such as fat, hemorrhage, fluid levels) and anatomic extent of bone tumors. CT provides complementary information, with its ability to detect subtle matrix mineralization or periosteal reaction that may not be seen on radiographs or MRI. This publication focuses on six common variants to guide diagnosis and management of primary bone tumors. In addition to conventional radiographs, appropriate use of MRI, CT, PET/CT, bone scan, and ultrasound are discussed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Neurotrophic tyrosine receptor kinase (NTRK)-rearranged spindle cell neoplasm is a recently characterized soft tissue tumor and has been classified as provisional by the World Health Organization. Detection of the genetic rearrangement is important because these tumors are amenable to targeted tyrosine kinase inhibitor therapy, which can play a key role in patients with unresectable or advanced disease. Although the spectrum of histopathology associated with this entity is broad, one notable feature is the infiltrative growth pattern, which is most reminiscent of lipofibromatosis-like neural tumor. Description of their diverse histologic attributes has aided recognition, but so far little attention has been paid to correlating the gross appearance and imaging features of these lesions. In this report, we describe the clinical, imaging, histopathological, and genetic features of a soft tissue NTRK-rearranged spindle cell neoplasm. Inclusion of this more recently identified entity into the imaging differential of tumors with intratumoral relatively hypovascular nodules and infiltrative margins is important because testing for NTRK rearrangement is not routinely performed.

Hand and wrist injuries are common reasons for musculoskeletal-related emergency department visits. Imaging is essential for evaluating many of these injuries. In most cases, conventional radiographs provide sufficient information to guide the treating clinician. This review focuses on seven common variants to guide diagnosis of hand and wrist injuries. In addition to radiographs, appropriate use of CT, MRI, bone scan, and ultrasound are discussed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

MRI is a valuable diagnostic tool that has become an essential part of an orthopaedic surgeon's practice. When acquired in the appropriate clinical setting, an MRI can direct patient management as surgical versus nonsurgical, guide surgical decision making, and even predict patient outcomes. The quality of MRI obtained and quality of the radiology report received varies. Ultimately, the orthopaedic surgeon must interpret the available imaging and apply these findings to treat the patient. The current day practicing orthopaedic surgeon should be familiar with interpreting common MRIs. Although subspecialized orthopaedic surgeons usually have experience and understanding of MRIs in their field, the general orthopaedic surgeon and those in-training will encounter the gamut of musculoskeletal MRIs. This review focuses on common injuries that can occur in the elbow and provides an approach to minimize missed findings.

The ongoing coronavirus disease 2019 (COVID-19) pandemic has increased the need for safe and efficient testing as a key containment strategy. Drive-through testing with nasopharyngeal swab has been implemented in many places in the USA as it allows for expeditious testing of large numbers of patients, limits healthcare workers’ risk of exposure, and minimizes the use of personal protective equipment. We present a case where the aluminum shaft of the nasopharyngeal swab fractured during specimen collection at a drive-through testing facility and was suspected to have remained in the asymptomatic patient. Initial evaluation with a series of radiographs covering the skull base, neck, chest, and abdomen did not reveal the swab. On further clinical evaluation, the swab was found endoscopically, lodged between the left inferior turbinate and nasal floor, and was removed by an otorhinolaryngologist. Using a phantom model, we aimed to delineate an imaging technique to better visualize the aluminum shaft of the nasopharyngeal swab on radiographs to help in identification. A technique using lower tube voltage (kVp) with tight collimation centered at the nasal bones area produced the best visualization of the aluminum shaft of the swab. Recognition that aluminum foreign bodies may be difficult to visualize radiographically and optimization of radiograph acquisition technique may help guide clinical management in unusual cases. Further evaluation with computed tomography or endoscopy should be considered in suspected cases where radiographs are negative.

BACKGROUND. CT attenuation thresholds that accurately distinguish enostoses from untreated osteoblastic metastases have been published. In the Mayo Clinic practices, these thresholds have been applied more broadly to distinguish benign sclerotic bone lesions other than enostoses from osteoblastic metastases. OBJECTIVE. The purpose of this article is to determine if CT attenuation thresholds allow the distinguishing of benign sclerotic bone lesions from osteoblastic metastases in patients undergoing bone biopsy. METHODS. A retrospective search was conducted to identify sclerotic lesions described on CT between October 7, 1998, and July 15, 2018, that underwent subsequent biopsy. Two musculoskeletal radiologists recorded lesions' maximum and mean attenuation. Using previously published attenuation thresholds, sensitivity and specificity for differentiating benign sclerotic lesions from osteoblastic metastases were calculated. ROC curve analysis was performed to determine if more appropriate attenuation thresholds exist. Intraclass correlation coefficients (ICCs) were computed. RESULTS. A total of 280 patients met inclusion criteria. Of those, 162 had malignant biopsy results and 118 had benign biopsy results. Of the 162 malignant lesions, 81 had received prior treatment. Maximum and mean attenuation were not significantly different between benign and malignant lesions for either reader (all p > .05). For reader 1, to distinguish benign from malignant lesions, a maximum attenuation threshold of more than 1060 HU resulted in sensitivity of 23.7%, specificity of 87.0%, and accuracy of 60.6%. A mean attenuation threshold of greater than 885 HU resulted in sensitivity of 19.5%, specificity of 90.7%, and accuracy 60.7%. ROC curve analysis showed AUCs for mean and maximum attenuation thresholds of 51.8% and 54.6%, respectively. Subgroup analyses of benign versus malignant and treated versus untreated lesions had similar results. Similar findings were obtained for reader 2. The two readers' ICC was 0.946 for maximum attenuation and 0.918 for mean attenuation. CONCLUSION. Published attenuation thresholds for distinguishing enostoses from osteoblastic metastases had slightly decreased specificity and markedly decreased sensitivity when applied to the differentiation of benign sclerotic lesions from osteoblastic metastases in our sample of biopsy-proven lesions. ROC analysis showed no high-performing attenuation threshold alternative. CLINICAL IMPACT. Published CT attenuation thresholds intended for distinguishing enostoses from osteoblastic metastases should not be used more broadly. More accurate alternative thresholds could not be derived.

To determine the frequency of non-diagnostic and discordant results from bone and soft tissue biopsies performed at our institution over a 3-year period and to investigate whether implementation of a weekly musculoskeletal radiology-pathology correlation conference decreased the time to appropriate patient management in cases of discordance.Consecutive image-guided core needle biopsy results obtained over a 12 month period of time were reviewed in a retrospective fashion. Following implementation of the correlation conference, subsequent consecutive image-guided core needle biopsy results obtained over a 26 month period of time were reviewed in a prospective fashion. For non-diagnostic and discordant cases, the time in days from date of availability of the biopsy result to date of documentation of a specific follow-up action plan was recorded.Diagnostic yield was 96.5% and 94.9% for the retrospective and prospective periods, respectively. There were four discordant results in the retrospective cohort (1.7%) and seven discordant results in the prospective cohort (2.1%). Following implementation of the weekly correlation conference, there was significant decrease (p 0.05) in median time from a discordant biopsy result to follow-up action plan. There were no unnecessary surgeries, litigation, or other unfavorable consequences in either cohort.Image-guided core needle biopsies of bone and soft tissue provide high diagnostic yield, often with specific diagnoses. The statistically significant decrease in number of days to follow-up action plan for discordant results suggests radiology-pathology review has a positive impact on patient care. Subjective benefits from communication and educational standpoints are also noteworthy.

Gout is the most common inflammatory arthritis and is increasing in relevance due to its rising prevalence and incidence. Dual-energy CT (DECT) and ultrasound (US) are the most frequently used imaging modalities for the diagnosis of gout and for the follow-up of patients receiving therapy. Although DECT has the highest diagnostic accuracy for gout and shows consistently excellent reader agreement in the assessment of urate deposition change after therapy, US also performs well and remains just as important an imaging tool in these realms due to its practical advantages in cost, availability, and safety. This article reports the current status of these two modalities in regard to diagnosis and therapy follow-up.

Imaging is an integral component of the evaluation of patients with a suspected soft-tissue mass. Imaging can not only confirm the presence of a mass but can provide essential information necessary for diagnosis, local staging, and biopsy planning. Although the objectives of the evaluation have not changed, the choices available for imaging of musculoskeletal masses have evolved dramatically in recent years. The purpose of this document is to identify the most common clinical scenarios and the most appropriate imaging for their assessment on the basis of the current literature and to provide general guidance for those scenarios that are not specifically addressed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Shoulder pain is one of the most common reasons for musculoskeletal-related physician visits. Imaging plays an important role in identifying the specific cause of atraumatic shoulder pain. This review is divided into two parts. The first part provides a general discussion of various imaging modalities (radiographs, arthrography, nuclear medicine, ultrasound, CT, and MRI) and their usefulness in evaluating atraumatic shoulder pain. The second part focuses on the most appropriate imaging algorithms for specific shoulder conditions including: rotator cuff disorders, labral tear/instability, bursitis, adhesive capsulitis, biceps tendon abnormalities, postoperative rotator cuff tears, and neurogenic pain. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Inflammatory sacroiliitis or the seronegative axial spondyloarthropathies often presents as back pain or sacroiliac joint pain of more than 3-month duration with inflammatory symptoms and typically in patients younger than 45 years of age. Imaging plays an important role in diagnosis and disease monitoring. This article addresses the appropriate sequence of initial imaging for evaluation of a suspected spondyloarthropathy, the imaging follow-up of treatment response and the special considerations for imaging of trauma in patients with ankylosis of the spine. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Infection of the musculoskeletal system is a common clinical problem. Differentiating soft tissue from osseous infection often determines the appropriate clinical therapeutic course. Radiographs are the recommend initial imaging examination, and although often not diagnostic in acute osteomyelitis, can provide anatomic evaluation and alternative diagnoses influencing subsequent imaging selection and interpretation. MRI with contrast is the examination of choice for the evaluation of suspected osteomyelitis, and MRI, CT, and ultrasound can all be useful in the diagnosis of soft tissue infection. CT or a labeled leukocyte scan and sulfur colloid marrow scan combination are alternative options if MRI is contraindicated or extensive artifact from metal is present. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

MRI of articular cartilage (AC) integrity has potential to become a biomarker for osteoarthritis progression. Traditional MRI sequences evaluate AC morphology, allowing for the measurement of thickness and its change over time. In the last two decades, more advanced, dedicated MRI cartilage sequences have been developed aiming to assess AC matrix composition non-invasively and detect early changes in cartilage not captured on morphological sequences. T2-mapping and T1ρ sequences can be used to estimate the relaxation times of water inside the AC. These sequences have been introduced into clinical protocols and show promising results for cartilage assessment. Extracelullar matrix can also be assessed using diffusion-weighted imaging and diffusion tensor imaging as the movement of water is limited by the presence of extracellular matrix in AC. Specific techniques for glycosaminoglycans (GAG) evaluation, such as delayed gadolinium enhanced MRI of cartilage or Chemical Exchange Saturation Transfer imaging of GAG, as well as sodium imaging have also shown utility in the detection of AC damage. This manuscript provides an educational update on the physical principles behind advanced AC MRI techniques as well as a comprehensive review of the strengths and weaknesses of each approach. Current clinical applications and potential future applications of these techniques are also discussed.

Diabetes-related foot complications such as soft-tissue infection, osteomyelitis, and neuropathic osteoarthropathy account for up to 20% of all diabetic-related North American hospital admissions. Radiography of the foot is usually appropriate as the initial screening examination in diabetic patients with suspected osteomyelitis of the foot. For follow-up examination, MRI of the foot with or without contrast enhancement demonstrates excellent soft-tissue contrast and sensitivity to marrow abnormalities with high-resolution detail in multiple anatomic planes and is usually appropriate when osteomyelitis or early neuropathic arthropathy is suspected. This publication of diabetes-related foot complications summarizes the literature and makes recommendations for imaging based on the available data. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The purpose of this study is to investigate the variation in attenuation values (expressed as Hounsfield units) for L1 vertebral body trabecular bone at different tube voltages used in dual-energy CT (DECT) and to remind physicians to consider changes in attenuation values when they approach opportunistic screening for osteoporosis.Consecutive patients who underwent DECT examination of the abdomen and pelvis for suspected urolithiasis were included in the study. Attenuation noted on CT of the L1 trabecular bone performed with the use of tube voltages of 80, 100, and 140 kV was recorded. The correlation between the attenuation noted when the tube voltage was 140 kV and the attenuation noted when the tube voltage was either 80 or 100 kV was calculated, and differences in the mean CT attenuation values were compared.The mean attenuation values from L1 trabecular bone measurement performed for 191 patients were analyzed. As expected, the mean attenuation values decreased as the tube voltage increased. There was a strong correlation between the attenuation values noted when tube voltages of 80 and 140 kV were used (rWe confirmed that attenuation values of L1 trabecular bone, unlike attenuation values of fat, fluid, or soft tissue, vary at different CT x-ray tube voltages. Therefore, standard reference attenuation values for trabecular bone seen at 120 kV cannot be applied to other single-energy settings, DECT, or CT examinations where dose modulation software automatically raises or lowers the tube voltage from 120 kV. Knowledge of the specific energy spectra used is essential before performing opportunistic CT evaluation for osteoporosis.

To describe the technique of iodine125 (I125) seed deployment into nonpalpable soft tissue masses under direct ultrasound (US) or CT guidance for intraoperative localization. Patients considered candidates for radioactive seed localization (RSL) based on advanced imaging findings underwent an ultrasound examination of the area of concern to verify sonographic visualization of the targeted mass. If the mass was not visible sonographically, CT was used for guidance. Patients were scheduled for surgery 1–4 days after seed implantation. Intraoperative frozen section pathological analysis was performed on all patients. Operative time, specimen volume, intraoperative margin status, and final margin status were recorded. Following the surgery, patients and surgeons completed satisfaction surveys. Ten patients underwent seed placement between 1 and 4 days prior to surgery. All patients had successful surgical resection of the targeted mass with removal of all implanted radioactive seed(s). There was no seed migration. Intraoperative frozen-section margins were negative (>2 mm) in 6/10 patients. Final surgical margins were negative in 9/10 patients. The patient with a positive margin at final pathology did not undergo further resection due to the benign nature of the mass. Patient and surgeon satisfaction survey results were highly positive. All four surgeons reported a strong preference for seed localization over wire localization. RSL is an effective, reliable, and safe technique for preoperative localization of nonpalpable soft tissue masses and yields high patient and surgeon satisfaction.

Hand and wrist injuries are common reasons for musculoskeletal-related emergency department visits. Imaging is essential for evaluating many of these injuries. In most cases, conventional radiographs provide sufficient information to guide the treating clinician. This review focuses on seven common variants to guide diagnosis of hand and wrist injuries. In addition to radiographs, appropriate use of CT, MRI, bone scan, and ultrasound are discussed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Gout is the most common inflammatory arthritis and is increasing in prevalence and incidence in many countries worldwide. Accurate diagnosis is important to direct treatment that may include chronic medication. Burden quantification and treatment monitoring are key in the effective care of patients with gout. This review highlights the positive impact of dual-energy computed tomography (DECT) on the evaluation of gout patients and discusses common imaging artifacts that limit this imaging modality. DECT has become the most accurate imaging method for confirming or excluding gout. Of note, however, it has reduced sensitivity in early disease, including initial attacks. Burden quantification is another important role of DECT, which can now be performed using automated software methods, allowing for a more reliable assessment of treatment effect. However, the analysis of gout DECT images can be impeded by artifacts related to the DECT reconstruction technique. DECT is the most sensitive and specific imaging modality for diagnosis, burden quantification, and treatment monitoring in patients with gout. A working knowledge of common DECT artifacts is essential for mitigating their occurance and misinterpretation.

Vertebral compression fractures (VCFs) have various causes, including osteoporosis, neoplasms, and acute trauma. As painful VCFs may contribute to general physical deconditioning, management of painful VCFs has the potential for improving quality of life and preventing superimposed medical complications. Various imaging modalities can be used to evaluate a VCF to help determine the etiology and guide intervention. The first-line treatment of painful VCFs has been nonoperative or conservative management as most VCFs show gradual improvement in pain over 2 to 12 weeks, with variable return of function. There is evidence that vertebral augmentation (VA) is associated with better pain relief and improved functional outcomes compared to conservative therapy for osteoporotic VCFs. A multidisciplinary approach is necessary for the management of painful pathologic VCFs, with management strategies including medications to affect bone turnover, radiation therapy, and interventions such as VA and percutaneous thermal ablation to alleviate symptoms. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Traumatic shoulder pain is pain directly attributed to a traumatic event, either acute or chronic. This pain may be the result of either fracture (the clavicle, scapula, or proximal humerus) or soft-tissue injury (most commonly of the rotator cuff, acromioclavicular ligaments, or labroligamentous complex). Imaging assessment of traumatic shoulder pain begins with conventional radiography and, depending on physical examination findings, will require MRI or MR arthrography for assessment of soft-tissue injuries and CT for delineation of fracture planes. Ultrasound excels in assessment of rotator cuff injuries but has limited usefulness for assessment of the deep soft-tissues. CT angiography and conventional arteriography are helpful for assessment of vascular injury, and bone scintigraphy can be used in assessment of complex regional pain syndrome after traumatic shoulder injury. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Imaging is an integral component of the evaluation of patients with a suspected soft-tissue mass. Imaging can not only confirm the presence of a mass but can provide essential information necessary for diagnosis, local staging, and biopsy planning. Although the objectives of the evaluation have not changed, the choices available for imaging of musculoskeletal masses have evolved dramatically in recent years. The purpose of this document is to identify the most common clinical scenarios and the most appropriate imaging for their assessment on the basis of the current literature and to provide general guidance for those scenarios that are not specifically addressed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

A number of benign bone tumours can be treated with curettage and packing with either bone cement or graft. It is essential that the radiologist be familiar with both the normal and abnormal post-operative imaging appearance of these treated tumours. Through the use of numerous imaging examples, we aim to provide a pictorial review of the expected post-operative appearance of benign bone tumours treated with curettage and packing, as well as the imaging features of recurrence, the most common potential complication.

The purpose of this study is to evaluate the histopathologic diagnostic yield, sample size, procedural time, and dose-length product (DLP) for the biopsy of CT-occult lesions found at MRI or PET or both.A retrospective review of our radiology information system for biopsies of CT-occult lesions using CT guidance from January 1, 2010, through December 31, 2014, was performed and compared with a selection of CT-guided biopsies of CT-evident bone lesions during the same period. The data were then evaluated for diagnostic yield of histopathologic diagnosis, procedural time, use of sedation medication, DLP, and size of specimens obtained.A total of 30 CT-occult biopsies met the inclusion criteria. Twenty-seven of those biopsies had results that were concordant with the patient's primary histopathologic diagnosis, imaging findings, and clinical course. In the CT-evident lesion group, concordant histopathologic abnormalities were identified in 27 of 30 patients. There was a statistically significant increase in number of samples obtained for the CT-evident lesions compared with CT-occult lesions. There was no statistically significant difference in total specimen length, DLP, number of CT scans, procedural time, or use of sedation medication between the CT-occult and CT-evident biopsy groups.Biopsy of CT-occult lesions using anatomic landmarks achieves diagnostic yields similar to those for CT-guided biopsy of CT-evident lesions.

Hemangiomas of the articular synovium are rare and commonly associated with recurrent joint swelling and painful limitation of motion. The knee joint is the most commonly involved site, with most patients diagnosed in the second to third decade of life [1]. Although over 200 cases have been reported in the English-language medical literature, only three have originated within the hip joint, all of which were in adult patients reported in the surgical literature [2–4]. We describe a histologically proven synovial hemangioma of the hip joint in a pediatric patient that invaded the femur, acetabulum, and adjacent soft tissues, with a detailed discussion of the differential diagnosis based on the radiographic and magnetic resonance imaging (MRI) findings.

This article reviews the basics of image-guided intervention of musculoskeletal neoplasms. Image-guided procedures are playing an ever-increasing role in the diagnosis, staging, and treatment of musculoskeletal tumors. The successful handling of these lesions necessitates a multidisciplinary approach, with the radiologist working closely with the orthopedic oncologic surgeon, medical oncologist, radiation oncologist, and pathologist to ensure that the procedure is performed in a way that maximizes the chance of definitive diagnosis and/or the treatment effect while minimizing potential complications. To accomplish these goals, the radiologist must be familiar with the indications and contraindications for any biopsy or treatment, effective procedure planning (e.g., selection of biopsy path, type of imaging guidance and biopsy needle, etc.), proper specimen handling, and potential treatment options such as thermal ablation or cement augmentation. Continued involvement after the procedure-including follow-up to ensure that pathology is concordant with imaging-is also crucial.

Infection of the musculoskeletal system is a common clinical problem. Differentiating soft tissue from osseous infection often determines the appropriate clinical therapeutic course. Radiographs are the recommend initial imaging examination, and although often not diagnostic in acute osteomyelitis, can provide anatomic evaluation and alternative diagnoses influencing subsequent imaging selection and interpretation. MRI with contrast is the examination of choice for the evaluation of suspected osteomyelitis, and MRI, CT, and ultrasound can all be useful in the diagnosis of soft tissue infection. CT or a labeled leukocyte scan and sulfur colloid marrow scan combination are alternative options if MRI is contraindicated or extensive artifact from metal is present. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diabetes mellitus is increasingly prevalent and results in various clinically important musculoskeletal disorders affecting the limbs, feet, and spine as well as in widely recognized end-organ complications such as neuropathy, nephropathy, and retinopathy. Diabetic muscle ischemia-a self-limited disorder-may be confused with infectious or inflammatory myositis, venous thrombosis, or compartment syndrome. The absence of fever and leukocytosis, combined with the presence of bilaterally distributed lesions in multiple and often noncontiguous muscles in the legs, including the thighs, is suggestive of ischemia; by contrast, the presence of well-defined intramuscular abscesses with rimlike enhancement favors a diagnosis of infectious pyomyositis. In the diabetic foot, an ulcer, sinus tract, or abscess with an adjacent region of abnormal signal intensity in bone marrow favors the diagnosis of pedal osteomyelitis over that of neuropathic arthropathy. Contrast material-enhanced magnetic resonance imaging is important when planning the treatment of foot infections in diabetic patients because it allows the differentiation of viable tissue from necrotic regions that require surgical débridement in addition to antibiotic therapy. Subtraction images are particularly useful for visualizing nonviable tissue. Dialysis-associated spondyloarthropathy characteristically occurs in diabetic patients with a long history of hemodialysis. Intervertebral disk space narrowing without T2 signal hyperintensity, extensive endplate erosions without endplate remodeling, and facet joint involvement are suggestive of spondyloarthropathy instead of infectious diskitis or degenerative disk disease. Although the clinical features of these conditions may overlap, knowledge of the patient's medical history, coupled with recognition of key imaging characteristics, allows the radiologist to make a prompt and correct diagnosis that leads to appropriate management.

Acute nontraumatic chest pain is a common presenting symptom to the emergency department. Often, it is evaluated by MDCT with PE, aortic dissection, or coronary artery protocols. The parameters used for these MDCT protocols are very similar to those used in protocols for dedicated imaging of the musculoskeletal system. Thus, these studies are not only effective in evaluating for these traditional vascular causes of chest pain, but also in evaluating musculoskeletal causes of chest pain, including those of infectious, rheumatologic, and systemic causes. In essence, every MDCT of the chest is also a musculoskeletal examination of the chest and anyone interpreting these images must be familiar with the MDCT-imaging appearance of common musculoskeletal causes of acute nontraumatic chest pain.

Appropriate imaging modalities for the follow-up of malignant or aggressive musculoskeletal tumors include radiography, MRI, CT, (18)F-2-fluoro-2-deoxy-D-glucose PET/CT, (99m)Tc bone scan, and ultrasound. Clinical scenarios reviewed include evaluation for metastatic disease to the lung in low- and high-risk patients, for osseous metastatic disease in asymptomatic and symptomatic patients, for local recurrence of osseous tumors with and without significant hardware present, and for local recurrence of soft tissue tumors. The timing for follow-up of pulmonary metastasis surveillance is also reviewed. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

More than 500,000 visits to the emergency room occur annually in the United States, for acute knee trauma. Many of these are twisting injuries in young patients who can walk and bear weight, and emergent radiographs are not required. Several clinical decision rules have been devised that can considerably reduce the number of radiographs ordered without missing a clinically significant fracture. Although a fracture is seen on only 5% of emergency department knee radiographs, 86% of knee fractures result from blunt trauma. In patients with a fall or twisting injury who have focal tenderness, effusion, or inability to bear weight, radiographs should be the first imaging study obtained. If the radiograph shows no fracture, MRI is best for evaluating for a suspected meniscus or ligament tear, or the injuries from a reduced patellar dislocation. Patients with a knee dislocation should undergo radiographs and an MRI, as well as an angiographic study such as a fluoroscopic, CT, or MR angiogram. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures, by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

A number of benign bone tumours can be treated with curettage and packing with either bone cement or graft. It is essential that the radiologist be familiar with both the normal and abnormal post-operative imaging appearance of these treated tumours. Through the use of numerous imaging examples, we aim to provide a pictorial review of the expected post-operative appearance of benign bone tumours treated with curettage and packing, as well as the imaging features of recurrence, the most common potential complication.

A case of right knee intra-articular synovial sarcoma in a 26-year-old man is reported. The patient had experienced 12 to 18 months of chronic posterior right knee pain with flexion contracture of the leg. Magnetic resonance imaging (MRI) examination demonstrated nonspecific characteristics of a well-circumscribed, homogeneous mass within the posterior lateral compartment of the knee joint. The mass was isointense and hyperintense to muscle on T1- and T2-weighted sequences respectively, and initially clinically diagnosed as a localized tenosynovial giant cell tumor. However, histological examination showed the lesion to be a synovial sarcoma arising from the synovium of the knee joint. Synovial sarcoma may have a nonspecific MR appearance, especially when less than 5 cm in size, often simulating a less aggressive process. Primary intra-articular origin may predispose to earlier presentation, and therefore, radiological evaluation of smaller masses. Nonspecific MR characteristics of small, intra-articular masses provide a diagnostic dilemma. Synovial sarcoma should be considered in the differential diagnosis when distinguishing MR characteristics of other common joint-centered entities are not present.

Background: Diagnostic evaluation of rotator cuff muscle quality is important to determine indications for potential operative repair. Ultrasonography has developed into an accepted and useful tool for evaluating rotator cuff tendon tears; however, its use for evaluating rotator muscle quality has not been well established. The purpose of this study was to investigate the diagnostic performance and observer reliability of ultrasonography in grading fatty degeneration of the posterior and superior rotator cuff muscles. Methods: The supraspinatus, infraspinatus, and teres minor muscles were prospectively evaluated with magnetic resonance imaging (MRI) and ultrasonography in eighty patients with shoulder pain. The degree of fatty degeneration on MRI was graded by four independent raters on the basis of the modified Goutallier grading system. Ultrasonographic evaluation of fatty degeneration was performed by one of three radiologists with use of a three-point scale. The two scoring systems were compared to determine the diagnostic performance of ultrasonography. The interobserver and intraobserver reliability of MRI grading by the four raters were determined. The interobserver reliability of ultrasonography among the three radiologists was determined in a separate group of thirty study subjects. The weighted Cohen kappa, percentage agreement, sensitivity, and specificity were calculated. Results: The accuracy of ultrasonography for the detection of fatty degeneration, as assessed on the basis of the percentage agreement with MRI, was 92.5% for the supraspinatus and infraspinatus muscles and 87.5% for the teres minor. The sensitivity was 84.6% for the supraspinatus, 95.6% for the infraspinatus, and 87.5% for the teres minor. The specificity was 96.3% for the supraspinatus, 91.2% for the infraspinatus, and 87.5% for the teres minor. The agreement between MRI and ultrasonography was substantial for the supraspinatus and infraspinatus (kappa = 0.78 and 0.71, respectively) and moderate for the teres minor (kappa = 0.47). The interobserver reliability for MRI was substantial for the supraspinatus and infraspinatus (kappa = 0.76 and 0.77, respectively) and moderate for the teres minor (kappa = 0.59). For ultrasonography, the interobserver reliability was substantial for all three muscles (kappa = 0.71 for the supraspinatus, 0.65 for the infraspinatus, and 0.72 for the teres minor). Conclusions: The diagnostic performance of ultrasonography in identifying and grading fatty degeneration of the rotator cuff muscles was comparable with that of MRI. Ultrasonography can be used as the primary diagnostic imaging modality for fatty changes in rotator cuff muscles. Level of Evidence: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.