MR Angiography Series: MR Angiography of the Extremities

Highlights of the society for magnetic resonance angiography 2024 conference

The 36th Annual International Meeting of the Society for Magnetic Resonance Angiography (SMRA), held from November 12-15, 2024, in Santiago de Chile, marked a milestone as the first SMRA conference in Latin America. Themed "The Ever-Changing Landscape of MRA", the event highlighted the rapid advancements in magnetic resonance angiography (MRA), including cutting-edge developments in contrast-enhanced MRA, contrast-free techniques, dynamic, multi-parametric, and multi-contrast MRA, 4D flow, low-field solutions and artificial intelligence (AI)-driven technologies, among others. The program featured 174 attendees from 15 countries, including 43 early-career scientists and 30 industry representatives. The conference offered a rich scientific agenda, with 12 plenary talks, 24 educational talks, 98 abstract presentations, a joint SMRA-MICCAI challenge on intracranial artery lesion detection and segmentation and a joint session with the Society for Cardiovascular Magnetic Resonance (SCMR) emphasizing accessibility, low-field MRI, and AI's transformative role in cardiac imaging. The meeting's single-track format fostered engaging discussions on interdisciplinary research and highlighted innovations spanning various vascular beds. This paper summarizes the conference's key themes, emphasizing the collaborative efforts driving the future of MRA, while reflecting on SMRA's vision to advance research, education, and clinical practice globally.

CT Angiography of the Upper Extremities: Review of Acute Arterial Entities

Historically, evaluation of the upper extremity vasculature was performed using digital subtraction angiography. With the advancement of cross-sectional imaging and submillimeter isotropic data acquisition, CT angiography (CTA) has become an excellent noninvasive diagnostic tool for evaluation of the vasculature of the upper extremities. CTA allows quick evaluation of vessel patency and irregularity and achievement of the anatomic detail needed in preoperative planning. When interpreting CTA of the upper extremities, radiologists must be familiar with the normal vascular anatomy, common vascular anomalies, and pitfalls or artifacts that may mimic or mask abnormality. In this review, the authors provide an overview of the utility of CTA of the upper extremities. Also discussed are CTA techniques and the use of several newer technologies including dual-energy and photon-counting detector CT. The utility of CTA in patients with upper extremity trauma is explored, with a focus on assessing vascular injury. Other vascular abnormalities including infection, acute limb ischemia, and vasculitis are discussed. It is imperative for radiologists to be accustomed to CTA of the upper extremities in diagnosing acute vascular abnormalities and to recognize common pitfalls and mimics of these abnormalities. ©RSNA, 2025 Supplemental material is available for this article.

Multisystem Imaging Manifestations of Kidney Failure

Kidney failure (KF) refers to a progressive decline in glomerular filtration rate to below 15 ml/min per 1.73 m2, necessitating renal replacement therapy with dialysis or renal transplant. The hemodynamic and metabolic alterations in KF combined with a proinflammatory and coagulopathic state leads to complex multisystemic complications. The imaging hallmark of systemic manifestations of KF is bone resorption caused by secondary hyperparathyroidism. Other musculoskeletal complications include brown tumor, osteosclerosis, calcinosis, soft-tissue calcification, and amyloid arthropathy. Cardiovascular complications and infections are the leading causes of death in KF. Cardiovascular complications include accelerated atherosclerosis, cardiomyopathy, pericarditis, myocardial calcinosis, and venous thromboembolism. Neurologic complications such as encephalopathy, osmotic demyelination, cerebrovascular disease, and opportunistic infections are also frequently encountered. Pulmonary complications include edema and calcifications. Radiography and CT are used in assessing musculoskeletal and thoracic complications, while MRI plays a key role in assessing neurologic and cardiovascular complications. CT iodinated contrast material is generally avoided in patients with KF except in situations where the benefit of contrast-enhanced CT outweighs the risks and in patients already undergoing maintenance dialysis. At MRI, group II gadolinium-based contrast material can be safely administered in patients with KF. The authors discuss the extrarenal systemic manifestations of KF, the choice of imaging modality in their assessment, and imaging findings of complications. ©RSNA, 2024 Supplemental material is available for this article.

Magnetic Resonance Angiography of the Arteries of the Upper and Lower Extremities

Magnetic resonance angiography (MRA) is a powerful tool for assessing upper and lower extremity artery pathologies. In addition to the classic advantages of MRA, such as the absence of radiation and iodinated contrast exposure, it can provide high temporal resolution/dynamic images of the arteries with high soft tissue contrast. Although it has a relatively lower spatial resolution than computed tomography angiography, MRA does not cause blooming artifacts in heavily calcified vessels, which is crucial in small vessel assessment. Although contrast-enhanced MRA is the most preferred technique to assess extremity vascular pathologies, recent advances in non-contrast MRA protocols provide an alternative imaging technique for patients with chronic kidney disease.