Radiographics最新文献

Enhanced myometrial vascularity (EMV) is a common postpregnancy (ie, postpartum, postpregnancy termination, and postpregnancy loss) sonographic finding that represents involuting myometrial hypervascularity of the placental bed in the early puerperium and may persist if retained products of conception (RPOC) are present. On color Doppler US images, EMV is characterized by tortuous and dilated myometrial vessels with high-velocity and turbulent flow. These features can be easily mistaken for an arteriovenous malformation (AVM). However, despite sharing overlapping flow patterns, AVM and EMV are fundamentally distinct. AVMs are vascular congenital malformations, whereas EMV is a dynamic finding in the postpregnancy state related to persistent or involuting uteroplacental circulation. Most EMVs that come to medical attention regress spontaneously after expulsion of the associated RPOC. AVMs, on the other hand, are not associated with pregnancy, do not regress spontaneously, and are difficult to treat, often requiring repeated embolization sessions with liquid embolic agents. By becoming familiar with EMV, radiologists may better serve patients and referring clinicians with guidance for further investigation or treatment (when appropriate), thereby preventing unnecessary interventions, hysterectomies, or potential complications associated with such treatments. The authors clarify the definitions of EMV, AVM, and other pertinent terms, discuss the physiology of the uteroplacental circulation and postpregnancy EMV, address the pathogenesis of persistent EMV associated with RPOC, and provide an overview of the imaging features and management of EMV. ^©The Author(s) 2026. Published by the Radiological Society of North America under a CC BY 4.0 license. Supplemental material is available for this article. See the invited commentary by Kirsch and Ponder in this issue.

Gynecologic pelvic MRI is a crucial imaging modality for problem solving, offering superior soft-tissue contrast and multiplanar capabilities for the detailed evaluation of female patients across a range of indications. Accurate interpretation of gynecologic pelvic MRI depends on using protocols tailored to the clinical indication, reviewing the patient's clinical history (such as age, symptoms, medical and surgical history, and genetic mutations), and considering laboratory data. A comprehensive understanding of the female pelvic anatomy, best visualized on high-resolution multiplanar T2-weighted images, is also essential. A systematic step-by-step approach to lesion evaluation further contributes to accurate interpretation. This process begins with determining lesion origin. Once identified, evaluating lesion tissue composition and assessing solid tissue morphology enables lesion classification into one of the following categories: (a) T1-hyperintense lipid-containing lesions, (b) T1-hyperintense blood-containing lesions without solid tissue, (c) cysts (simple or proteinaceous fluid) without solid tissue, (d) cystic or solid lesions with dark T2/dark diffusion-weighted imaging (DWI) solid tissue, and (e) cystic or solid lesions with non-dark T2/non-dark DWI solid tissue. Based on lesion origin and these categories, the differential diagnosis can be developed and communicated in a structured radiology report, ensuring clear and concise communication with the treatment team. Supplemental material is available for this article. ^©RSNA, 2026 See the invited commentary by Ghafoor and Stocker in this issue.

Coccidioidomycosis, a disease induced by the dimorphic fungi Coccidioides immitis and Coccidioides posadasii, is endemic to the southwestern United States and occurs with a myriad of clinical and imaging manifestations, which range from limited pulmonary disease to disseminated multiorgan infections. Humans are infected when arthroconidia in the soil are disturbed and dispersed into the air. Once inhaled, arthroconidia form spherules, which trigger a host cell-mediated immune response. If this response is adequate, it results in granuloma formation, halting the infection. However, an insufficient response leads to morphologic conversion into endospores that are capable of hematogenous and lymphatic dissemination to other organ systems. Given the airborne route of transmission, there is a propensity for pulmonary infections, which represent the most common disease manifestation of coccidioidomycosis. CT features of pulmonary involvement include nodules, lobar or segmental consolidation, and multifocal consolidation in the acute phase, which can occur with mediastinal adenopathy and/or pleural effusions. Extrapulmonary dissemination is rare, occurring in 1%-5% of patients. Musculoskeletal involvement is common in cases of dissemination, with discitis-osteomyelitis being a frequent manifestation, often demonstrating relative disk sparing analogous to that seen with tuberculosis or other causes of atypical infectious spondylitis. When osteomyelitis of the appendicular skeleton is juxta-articular, it can progress to septic arthritis, with fungal tenosynovitis and soft-tissue abscesses being less common musculoskeletal features. Neurologic involvement is frequent, with complications including meningitis, cerebritis, and abscess formation, which can induce vasculopathic and neuropathic sequelae, leading causes of morbidity and mortality in cases of dissemination. Other systems are less commonly involved, but conditions include pyelonephritis, peritonitis, lymphadenitis, and endocarditis. ^©RSNA, 2026 Supplemental material is available for this article.

The shoulder girdle, which includes the clavicle, scapula, and proximal humerus, forms a dynamic scaffold for seamless motion and load transfer to the axial skeleton. CT with multiplanar reformatted and volume-rendered images allows precise characterization, measurement, and injury classification and is particularly useful for complex high-energy disruptions encountered in trauma centers. The spectrum of shoulder girdle injuries spans clavicle fractures, acromioclavicular joint separations, floating shoulder patterns, glenohumeral fracture-dislocations, glenoid fossa fractures, proximal humerus fractures, and scapulothoracic dissociations. Most fractures are treated conservatively with sling immobilization, and absolute surgical indications are limited to open and impending open fractures or neurovascular compromise. However, since injury severity correlates with instability, chronic pain, and functional impairment, high-grade disruptions may warrant surgical intervention when specific criteria are met. Classification systems-such as the Neer, Rockwood, and Ideberg-Goss frameworks-combined with measurements including the glenopolar angle, glenoid index, glenoid track, and metaphyseal head extension inform the surgical risk-benefit calculus and help determine optimal surgical techniques and exposures. Radiologists can provide intuitive, salient reports and add value to surgical treatment planning discussions by synthesizing biomechanical first principles, grading systems, and key measurement parameters to arrive at the most feasible and likely surgical treatment options. ^©RSNA, 2025 Supplemental material is available for this article.

Focal liver lesion (FLL) evaluation is a common indication for liver MRI. The choice of contrast agent is critical, as extracellular agents (ECAs) and hepatobiliary agents (HBAs [eg, gadoxetate]) have different strengths and weaknesses. ECAs are useful in depicting progressive centripetal enhancement (eg, hemangiomas), whereas HBAs are useful for identifying hepatocyte-containing lesions (eg, focal nodular hyperplasia) and offer high sensitivity for detecting hepatocyte-deficient lesions (eg, hepatic metastases). MRI with HBAs can result in uncertainty in distinguishing hemangiomas from metastases, as some hemangiomas are hypoenhancing at venous and transitional phases and both lesion types are hypointense at the hepatobiliary phase (HBP). There may also be uncertainty in distinguishing between hepatic adenomas and focal nodular hyperplasia if an ECA is used, necessitating a follow-up evaluation with an HBA. Additionally, HBAs can induce transient arterial phase motion, potentially obscuring arterial phase hyperenhancement. Hybrid agent imaging with gadobenate provides ECA-like behavior during dynamic imaging, but the HBP requires a 1-hour delay, often with a less robust HBP. A sequential dual-contrast agent protocol, imaging dynamically with an ECA followed by an HBA for HBP imaging, offers the advantages of both types of agents and is ideally suited for the initial characterization of FLLs. The authors describe the benefits and pitfalls of single-contrast agent FLL imaging, the rationale for dual-contrast agent FLL imaging, and the specifics of a dual-contrast agent protocol. Advantages of a dual-contrast agent technique are illustrated through case examples. The reader will be empowered to adopt a dual-contrast agent liver MRI protocol for greater diagnostic confidence and accuracy in initial FLL characterization. ^©RSNA, 2025 Supplemental material is available for this article. See the invited commentary by Welle and Venkatesh in this issue.

Acute ischemic stroke is a leading cause of morbidity and mortality requiring timely intervention. Mechanical thrombectomy is an increasingly prevalent technique for removal of the clot burden in patients with acute ischemic stroke with a targetable vessel, enabling treatment within 24 hours of symptom onset. In the post-mechanical thrombectomy period, patients must be monitored closely for complications and in preparation for secondary prevention therapy. Patients typically undergo serial follow-up imaging examinations with multiple modalities, including newer techniques such as dual-energy CT. The radiologist should be aware of the expected findings in the post-mechanical thrombectomy period, such as contrast material staining, and be able to distinguish these from complications. Post-mechanical thrombectomy complications can arise anywhere along the instrumentation path, involving both intracranial and extracranial findings. A conceptual understanding of the clinical implications of various complications is presented to help radiologists appropriately contextualize their findings at follow-up imaging. ^©RSNA, 2025 Supplemental material is available for this article.

Obtaining arterial access is one of the most technically challenging aspects of pediatric angiography and endovascular interventions. Due to anatomic and physiologic differences, pediatric arteries are small and prone to vasospasm and dissection. Together with the lack of dedicated pediatric-specific equipment, the risks for arterial occlusion and thrombotic complications are significantly higher in children: up to 16% in those who weigh less than 15 kg. Detailed preprocedural planning, including selection of an appropriate arterial access site, periprocedural optimization, use of US guidance for arterial puncture, and meticulous postaccess care can help improve the success rate and reduce adverse outcomes. Although the transfemoral approach remains the conventional access route for the majority of pediatric angiographic examinations and transarterial interventions, alternative access routes including umbilical, radial, brachial, or axillary arteries can be useful in certain clinical scenarios. In neonates, the umbilical vessels are the preferred access site, and their use may prevent access-related complications in the extremities. In steno-occlusive aortoiliac conditions or in complex interventions involving downward-sloping visceral arteries, upper extremity access (eg, radial, brachial, and axillary, depending on artery size) can aid in the delivery of interventional devices. Compared with traditional transfemoral access, transradial access also has the advantage of allowing early ambulation. Use of intraprocedural unfractionated heparin and vasodilators can help reduce vasospasm and thrombosis in small arteries. The mainstay of treatment of arterial thrombosis is systemic anticoagulation therapy, while catheter-directed thrombolysis or thrombectomy is reserved for patients with critical limb ischemia resistant to anticoagulation medication. ^©RSNA, 2025 Supplemental material is available for this article.

Vasculitides are disorders characterized by inflammation of blood vessels and are typically classified by their size. Large vessel vasculitis (LVV) is divided into two main categories of giant cell arteritis (GCA) and Takayasu arteritis (TA). Although there are key distinguishing factors in their presentation, in reality, both conditions can behave nonspecifically with generalized symptoms making diagnosis challenging. Noninvasive imaging has a role in identifying, classifying, and staging LVV; often with a multimodality approach including US, CT and MRI with angiography, and fluorine 18 (¹⁸F)-fluorodeoxyglucose (FDG) PET/CT. The choice of imaging examination may vary according to patient presentation and local protocols, but international guidance recommends US as a first-line alternative to temporal artery biopsy in diagnosing GCA and mandates extracranial imaging when initial images are negative. In TA, cross-sectional body imaging is advised, ideally with MRI with angiography, owing to the lower radiation doses and effectiveness of structural assessment. Functional imaging with ¹⁸F-FDG PET/CT and advancements in vessel wall and diffusion-weighted MRI show promise in monitoring activity and assessing treatment response but require validation. The authors describe the epidemiology, presentation, pathogenesis, and management of the primary large vessel vasculitides; outline generic and specific multimodality imaging findings alongside technical aspects; and consider the role of imaging in monitoring disease activity and treatment response. Variable vessel and secondary vasculitides, which can involve large vessels, are briefly reviewed. ^©RSNA, 2025.

Pulmonary arteriovenous malformations (PAVMs) are abnormal connections between the pulmonary arteries and veins, bypassing the capillary network and exposing patients to serious complications such as stroke, brain abscess, and hemothorax. The estimated prevalence of PAVMs is approximately one in 2630 individuals, with hereditary hemorrhagic telangiectasia accounting for over 80% of cases. PAVMs are classified as simple, complex, or diffuse based on their angioarchitecture. Diagnostic evaluation involves transthoracic contrast-enhanced echocardiography for screening, chest CT for confirmation, and pulmonary angiography primarily for guiding embolization. Endovascular embolization is the preferred treatment and is typically performed with vascular plugs, although coils may be required for small or tortuous vessels. Postprocedural follow-up with CT is essential to detect persistent or new PAVMs. During pregnancy, PAVMs may enlarge and rupture, significantly increasing complication risks and necessitating close monitoring and treatment. Persistent PAVMs can develop after treatment due to four distinct mechanisms of reopening, each requiring a tailored management approach. The authors provide a comprehensive overview of PAVM angioarchitecture, step-by-step embolization techniques, and a comparative analysis of embolization devices, highlighting their advantages and limitations. Additionally, the authors also discuss follow-up protocols and strategies for managing persistent PAVMs, emphasizing the importance of early detection and timely intervention in preventing severe and potentially life-threatening complications. ^©RSNA, 2025 Supplemental material is available for this article.