Musculoskeletal Manifestations of COVID-19: Currently Described Clinical Symptoms and Multimodality Imaging Findings.

COVID-19, the clinical syndrome produced by infection with SARS-CoV-2, can result in multisystem organ dysfunction, including respiratory failure and hypercoagulability, which can lead to critical illness and death. Musculoskeletal (MSK) manifestations of COVID-19 are common but have been relatively underreported, possibly because of the severity of manifestations in other organ systems. Additionally, patients who have undergone sedation and who are critically ill are often unable to alert clinicians of their MSK symptoms. Furthermore, some therapeutic measures such as medications and vaccinations can worsen existing MSK symptoms or cause additional symptoms. Symptoms may persist or occur months after the initial infection, known as post-COVID condition or long COVID. As the global experience with COVID-19 and the vaccination effort increases, certain patterns of MSK disease involving the bones, muscles, peripheral nerves, blood vessels, and joints have emerged, many of which are likely related to a hyperinflammatory host response, prothrombotic state, or therapeutic efforts rather than direct viral toxicity. Imaging findings for various COVID-19-related MSK pathologic conditions across a variety of modalities are being recognized, which can be helpful for diagnosis, treatment guidance, and follow-up. The online slide presentation from the RSNA Annual Meeting is available for this article. ©RSNA, 2022.

Magnetic resonance imaging of musculoskeletal infections.

Magnetic resonance imaging (MRI) is a powerful imaging modality in the evaluation of musculoskeletal (MSK) soft tissue, joint, and bone infections. It allows prompt diagnosis and assessment of the extent of disease, which permits timely treatment to optimize long-term clinical outcomes. MRI is highly sensitive and specific in detecting the common findings of MSK infections, such as superficial and deep soft tissue oedema, joint, bursal and tendon sheath effusions, lymphadenopathy, bone marrow oedema, erosive bone changes and periostitis, and bone and cartilage destruction and sequestration. Contrast-enhanced MRI allows detection of non-enhancing fluid collections and necrotic tissues, rim-enhancing abscesses, heterogeneously or diffusely enhancing phlegmons, and enhancing active synovitis. Diffusion-weighted imaging (DWI) is useful in detecting soft-tissue abscesses, particularly in patients who cannot receive gadolinium-based intravenous contrast. MRI is less sensitive than computed tomography (CT) in detecting soft-tissue gas. This article describes the pathophysiology of pyogenic MSK infections, including the route of contamination and common causative organisms, typical MR imaging findings of various soft tissue infections including cellulitis, superficial and deep fasciitis and necrotizing fasciitis, pyomyositis, infectious bursitis, infectious tenosynovitis, and infectious lymphadenitis, and of joint and bone infections including septic arthritis and osteomyelitis (acute, subacute, and chronic). The authors also discuss MRI findings and pitfalls related to infected hardware and diabetic foot infections, and briefly review standards of treatment of various pyogenic MSK infections.

Radiologic Evaluation of Lower Leg, Ankle, and Foot Fracture Fixation Hardware.

Radiologists should be familiar with basic principles of fracture fixation and the normal imaging appearances of implant constructs and their complications. The surgeon's selection of external fixation, intramedullary nail fixation, open reduction and internal fixation, or some combination depends on patient factors, fracture configuration, injury to the soft tissue envelope, and surgeon experience. Complications including loss of fixation with resultant malalignment, nonunion, infection, and posttraumatic osteoarthritis present additional challenges for the surgeon as well as the radiologist. This article reviews the rationale behind fracture fixation in fractures of the lower leg, ankle, and foot. Examples of postoperative complications are also reviewed.

Update on Imaging of Knee Arthroplasties: Normal Findings and Hardware Complications.

Total knee arthroplasty (TKA) is the most common joint replacement performed. This article reviews the normal appearance of TKA including the most common types of arthroplasties as well as complications. Common complications at the present time are infection, aseptic loosening, and instability. Rarer complications such as polyethylene wear, periprosthetic fracture, and soft tissue pathology are also discussed. Although the mainstay of imaging is radiographs, newer techniques in TKA imaging such as computed tomography and magnetic resonance imaging are also reviewed.

Posterior dislocation of the long head biceps tendon: a case report, specific radiographic finding, and review of the literature.

Posterior dislocation of the long head of the biceps tendon uncommonly occurs with traumatic shoulder injury. The diagnosis is almost always associated with anterior shoulder dislocation which often cannot be reduced. We present a case of traumatic posterior dislocation of the long head of the biceps tendon with no reported history of shoulder dislocation, but instead a rare and specific radiographic finding. The imaging features are described, the relevant literature reviewed, and salient features discussed.

Rosai-Dorfman Disease: Manifestations Outside of the Head and Neck.

OBJECTIVE: Rosai-Dorfman disease (RDD) is an uncommon benign histiocytic disorder. Extranodal involvement occurs in 43% and most commonly involves the head and neck, skin, and bones. We review less common imaging findings outside the head and neck. CONCLUSION: The imaging manifestations of RDD overlap with a variety of neoplastic and nonneoplastic conditions. Confirmation of an RDD diagnosis is based on specific histologic features. Radiologic assessment is used to rule out multifocality on initial workup and to evaluate treatment response.

Liver Masses: What Physicians Need to Know About Ordering and Interpreting Liver Imaging.

PURPOSE OF REVIEW: This paper reviews diagnostic imaging techniques used to characterize liver masses and the imaging characteristics of the most common liver masses. RECENT FINDINGS: The role of recently adopted ultrasound and magnetic resonance imaging contrast agents will be emphasized. Contrast-enhanced ultrasound is an inexpensive exam which can confirm benignity of certain liver masses without ionizing radiation. Magnetic resonance imaging using hepatocyte-specific gadolinium-based contrast agents can help confirm or narrow the differential diagnosis of liver masses.

Imaging of Intrahepatic Cholangiocarcinoma.

Cholangiocarcinoma is the second most common primary hepatic malignancy and is a heterogeneous tumor of biliary epithelium. We discuss the risk factors, anatomic classification of cholangiocarcinoma (CC) as well as the different morphologic subtypes of CC. Imaging findings of CC on different modalities are described, focusing on intrahepatic CC. Recently recognized imaging features that carry prognostic significance, such as a worse prognosis in tumors that have more desmoplastic stroma, are detailed. Other benign and malignant entities that should be considered in the differential diagnosis of CC will also be discussed.

Paraspinal Fat Stranding as an Unexpected Finding on Body Computed Tomography: A Key to Early Detection of Spinal Osteomyelitis.

OBJECTIVE: At present, early detection of spinal osteomyelitis is a challenge. Patients may present with non-specific symptoms and diagnostic imaging studies may be obtained for seemingly unrelated complaints. Paraspinal fat stranding on body computed tomography (CT) as a sign of osteomyelitis is easily overlooked and has not been reported in the literature to our knowledge. The purpose of this study is to review findings on body CT that points to unsuspected spinal osteomyelitis. MATERIAL AND METHODS: A retrospective review of patients with spinal osteomyelitis who also had concomitant chest, abdominal, or pelvic CT scans between August 2013 and February 2017 yielded 10 patients who had confirmed osteomyelitis (ages between 51 and 75, mean age 64.8). Images and medical records were reviewed. RESULTS: The age of the patients ranged from 51 to 75 years (median value, 64). All patients had multiple underlying medical illnesses, and half of them had a known preceding infection such as sepsis or urinary tract infection. At presentation, three patients had a fever and two patients had neurologic deficits. Seven out of eight patients had elevated C-reactive protein and erythrocyte sedimentation rate, five patients had leukocytosis, and four patients had positive blood cultures. Paravertebral fat stranding and endplate erosions were observed in 9 and 6 cases, respectively, on initial body CT for unrelated indications, and subsequent magnetic resonance imaging confirmed osteomyelitis discitis. CONCLUSION: Clinically significant, but initially unsuspected, spinal pathology such as osteomyelitis may present on body CT scans. Earlier diagnosis of spinal osteomyelitis can be made by performing a focused evaluation of the paraspinal soft tissues and including osteomyelitis in the differential diagnosis, particularly in high-risk patients.

Hepatic actinomycosis - A potential mimicker of malignancy.

Actinomycosis is a rare granulomatous disease caused by commensal bacteria (Actinomycetaceae family) of the oropharynx, gastrointestinal, and urogenital tract. Infection most commonly involves the cervicofacial region but less frequently the abdominal region, typically secondary to a disruption of normal gastrointestinal mucosa. We present a patient with vague symptoms of fevers and myalgias and a recent diagnosis of rectal cancer. On CT, there were multiple centrally hypoattenuating hepatic lesions suspicious for metastasis vs abscesses, also confirmed by ultrasound. Initial image guided biopsy was non-diagnostic. Laparoscopic resection of one of the hepatic lesions showed pus consistent with an abscess. No organisms were identified by culture and a sample was sent to an outside laboratory for genomic polymerase chain reaction (PCR) analysis where Actinomyces DNA was isolated. This case report highlights a rare presentation of primary hepatic Actinomycosis and some of the challenges in diagnosing Actinomycosis due to its variable clinical and radiological manifestations and lack of diagnostic sensitivity by traditional microscopy and culture based techniques.

Texture analysis of placental MRI: can it aid in the prenatal diagnosis of placenta accreta spectrum?

PURPOSE: To determine if texture analysis can differentiate placenta accreta spectrum (PAS) from normal placenta on MRI. METHODS: We performed retrospective image analysis of 80 patients, comprised of 46 patients with PAS and 34 patients without PAS. Histopathology was used as the reference standard. Sagittal single shot fast spin echo T2-weighted MRI sequences acquired from a single institution were analyzed. Placental heterogeneity was quantified using in-house software on a Matlab platform, including the standard deviation of pixel intensity, coefficient of variation, gray-level co-occurrence matrices (GLCM), histogram-oriented gradients (HOG), and fractal analysis with box sizes from 2 to 512. Two-tailed unpaired Student's t test was used with statistical significance of p < 0.05. RESULTS: PAS was associated with higher values for standard deviation of pixel intensity and fractal analysis at every box size. Fractal analysis at box sizes 256 (p = 0.011) and 32 (p = 0.021), and standard deviation of pixel intensity (p = 0.023) were the most statistically significant. Fractal values at box size 256 for PAS was 0.13 versus 0.090 for patients without PAS, while standard deviation of pixel intensity was 3.7 for PAS versus 2.5 for patients without PAS. No statistically significant association between PAS and GLCM, coefficient of variation, and HOG was found. CONCLUSION: Statistically significant differences were found between normal and abnormal groups using standard deviation of pixel intensity and fractal analysis.

Colorectal-Vaginal Fistulas: Imaging and Novel Interventional Treatment Modalities.

Colovaginal and/or rectovaginal fistulas cause significant and distressing symptoms, including vaginitis, passage of flatus/feces through the vagina, and painful skin excoriation. These fistulas can be a challenging condition to treat. Although most fistulas can be treated with surgical repair, for those patients who are not operative candidates, limited options remain. As minimally-invasive interventional techniques have evolved, the possibility of fistula occlusion has enriched the therapeutic armamentarium for the treatment of these complex patients. In order to offer optimal treatment options to these patients, it is important to understand the imaging and anatomical features which may appropriately guide the surgeon and/or interventional radiologist during pre-procedural planning.

Promoting Collaborations Between Radiologists and Scientists.

Radiology as a discipline thrives on the dynamic interplay between technological and clinical advances. Progress in almost all facets of the imaging sciences is highly dependent on complex tools sourced from physics, engineering, biology, and the clinical sciences to obtain, process, and view imaging studies. The application of these tools, however, requires broad and deep medical knowledge about disease pathophysiology and its relationship with medical imaging. This relationship between clinical medicine and imaging technology, nurtured and fostered over the past 75 years, has cultivated extraordinarily rich collaborative opportunities between basic scientists, engineers, and physicians. In this review, we attempt to provide a framework to identify both currently successful collaborative ventures and future opportunities for scientific partnership. This invited review is a product of a special working group within the Association of University Radiologists-Radiology Research Alliance.

Myxoid-round cell liposarcoma: MRI appearance after radiation therapy and relationship to response.

Liposarcomas are classified into 4 different subtypes, with the myxoid-round cell variant demonstrating increased morbidity and metastatic potential dependent on cell composition. Unique to sarcomas, the myxoid-round cell liposarcoma is remarkably sensitive to radiation therapy in the pretreatment setting, owing to the tumor morphology and vascular distribution. Herein we report a case of myxoid-round cell liposarcoma within the deep soft tissues of the thigh of an 81-year-old male with excellent neoadjuvant response to radiation. We briefly review treatment options.

Angiosarcoma of the hand associated with pseudoaneurysm.

Angiosarcoma is a rare malignancy of vascular endothelial origin. We describe a case of angiosarcoma of the hand initially histopathologically diagnosed as a pseudoaneurysm, emphasizing the diagnostic importance of radiological pathologic concordance. Here we highlight the distinctive imaging and the histopathologic features of angiosarcoma, invaluable to its accurate and timely diagnosis.

Improved Image Quality of Low-Dose CT Pulmonary Angiograms.

OBJECTIVE: The use of CT pulmonary angiography (CTPA) to evaluate for pulmonary embolism has been increasing, and carries a significant radiation dose. We evaluate image quality of lower-dose images, taking into account patient size as well as the effects of image postprocessing. METHODS: A total of 250 CTPAs were retrospectively reviewed. The following parameters were obtained: kVp, mA, dose length product, Hounsfield units (HU) with standard deviation in the main pulmonary artery, transverse scout measurement, and subjective image quality. RESULTS: Radiation dose decreased 55% by reducing kVp from 120 to 100, and 60% from 100 to 80 kVp. Radiation dose decreased 82% from 120 to 80 kVp. Noise increased 38% from 120 kVp to 100 kVp, and increased 23% from 100 kVp to 80 kVp. Adding an overlapped reconstructed image decreased noise by 16% to 21%. Despite the increase in image noise, diagnostic quality was significantly improved at 80 and 100 kVp, compared with 120 kVp, with an average subjective quality rating of 3.8, 4.0, and 3.2, respectively, and an average pulmonary artery density of 536, 423, and 278 HU. Even in larger patients, qualitative image quality was better at 100 kVp compared with 120 kVp, with an average quality rating of 3.6 versus 2.9, respectively. CONCLUSIONS: Radiation dose exposure can be easily reduced on CTPA by lowering kVp, which at the same time improves image quality. Studies using a lower kVp were of significantly higher diagnostic quality. This held true even in larger patients.

Misplaced devices in the chest, abdomen, and pelvis: Part I.

Numerous medical devices are used in the chest and fewer in the abdomen and pelvis. They are frequently seen on various radiological studies in daily practice. Knowing the specific name of the device is not important. However, knowing the proper positioning and function of the device is necessary. It is a duty of the reporting radiologist to recognize the malpositioning or breakage of a medical device and to inform the responsible physician promptly, since these complications can have undesirable consequences and sometimes a fatal outcome.

Misplaced devices in the chest, abdomen, and pelvis: Part II.

Numerous medical devices are used in the chest and fewer in the abdomen and pelvis. They are frequently seen on various radiological studies in daily practice. Knowing the specific name of the device is not important. However, knowing the proper positioning and function of the device is necessary. It is a duty of the reporting radiologist to recognize the malpositioning or breakage of a medical device and to inform the responsible physician promptly, since these complications can have undesirable consequences and sometimes a fatal outcome.

Imaging spectrum of cholangiocarcinoma: role in diagnosis, staging, and posttreatment evaluation.

Cholangiocarcinoma, a tumor of biliary epithelium, is increasing in incidence. The imaging appearance, behavior, and treatment of cholangiocarcinoma differ according to its location and morphology. Cholangiocarcinoma is usually classified as intrahepatic, perihilar, or distal. The three morphologies are mass-forming, periductal sclerosing, and intraductal growing. As surgical resection is the only cure, prompt diagnosis and accurate staging is crucial. In staging, vascular involvement, longitudinal spread, and lymphadenopathy are important to assess. The role of liver transplantation for unresectable peripheral cholangiocarcinoma will be discussed. Locoregional therapy can extend survival for those with unresectable intrahepatic tumors. The main risk factors predisposing to cholangiocarcinoma are parasitic infections, primary sclerosing cholangitis, choledochal cysts, and viral hepatitis. Several inflammatory conditions can mimic cholangiocarcinoma, including IgG4 disease, sclerosing cholangitis, Mirizzi's syndrome, and recurrent pyogenic cholangitis. The role of PET in diagnosis and staging will also be discussed. Radiologists play a crucial role in diagnosis, staging, and treatment of this disease.

Ultrasound imaging of placenta accreta with MR correlation.

Placenta accreta is abnormal placental adherence or invasion of the myometrium or extrauterine structures. It is increasing in incidence because of increasing number of cesarean sections and is one of the main causes of excessive postpartum hemorrhage. Recognition of this entity is crucial because improved outcomes have been shown when the antenatal diagnosis of placenta accreta is made. Ultrasound is the first-line tool; magnetic resonance imaging (MRI) is complementary. Ultrasound and MRI features and MRI protocols will be reviewed.