The Renal Vasculature: What the Radiologist Needs to Know

The physiologic role of the kidneys is dependent on the normal structure and functioning of the renal vasculature. Knowledge and understanding of the embryologic basis of the renal vasculature are necessary for the radiologist. Common anatomic variants involving the renal artery (supernumerary arteries and prehilar branching) and renal vein (supernumerary veins, delayed venous confluence, retroaortic or circumaortic vein) may affect procedures like renal transplantation, percutaneous biopsy, and aortic aneurysm repair. Venous compression syndromes (anterior and posterior nutcracker syndrome) can be symptomatic and can be diagnosed with a combination of radiologic features. Renal artery stenosis is commonly atherosclerotic and is diagnosed with Doppler US, CT angiography, or MR angiography. Fibromuscular dysplasia, the second most common cause of renal artery narrowing, has a characteristic string-of-beads appearance resulting from multifocal stenoses and dilatations. Manifestations of renal vasculitis differ depending on whether the affected vessels are large, medium, or small. Renal vascular injury is graded according to the American Association for the Surgery of Trauma (AAST) renal injury scale, which defines vascular injury and active bleeding in renal injuries. Both renal arteries and veins are affected by primary neoplasms or secondarily by neoplasms from adjacent structures. Differentiation between bland thrombus and tumor thrombus and the extent of involvement dictate management in malignancies, especially renal cell carcinoma. Aneurysms, pseudoaneurysms, arteriovenous malformations, and arteriovenous fistulas can affect renal vessels and can be diagnosed with specific imaging features. The radiologist has a critical role in identification of specific imaging characteristics and establishing the diagnosis in the varied pathologic conditions affecting the renal vasculature, which is critical for directing management. Thus, the renal vasculature should be an integral part of radiologists' checklist. ^©RSNA, 2021.

Abdominal and pelvic radiographs of medical devices and materials-Part 1: gastrointestinal and vascular devices and materials

When compared with chest radiographs, medical devices of the abdomen and pelvis are less frequently seen. However, with recent advances in technology the interpreting radiologists are seeing more medical objects on these radiographs. The identification of these devices and materials are crucial for not only enabling the radiologist to understand the underlying background pathology but also for evaluating any related complications. An online survey of literature showed our review article to be the most detailed. In this first part of our two-part series, we discuss about the various gastrointestinal and vascular devices and materials seen on abdominal and pelvic radiographs.

Perforation of inferior vena cava and duodenum by strut of inferior vena cava filter: A case report

INTRODUCTION

An Inferior vena cava (IVC) filter is an intravascular filter that is implanted into the IVC to prevent pulmonary embolism in medical, surgical, and trauma patients. The insertion of an IVC filter is a relatively safe procedure, but rarely may be associated with symptomatic perforation of the IVC wall, particularly in the long term.

PATIENT CONCERNS AND DIAGNOSIS

A 74-year-old-woman with a medical history of IVC filter insertion visited the emergency department complaining of abdominal pain. A computed tomography scan showed perforation of the IVC wall and penetration into the duodenum by one of the filter's struts.

INTERVENTIONS

We performed a laparotomy to remove the IVC filter.

OUTCOMES

Postoperatively, the patient was admitted to the general ward. On hospital day 12, she was discharged without any complications. We followed her up and computed tomography did not show any abnormal findings six months after discharge.

LESSONS

There is currently no evidence testifying to the benefits of IVC filter removal. Detailed, evidence-based guidelines on the indications, timing and procedure for IVC filter removal are needed. Documenting cases of long-term complications of IVC filter s such as in this patient serve to accelerate the publication of updated guidelines and are aimed at improving outcomes of similar cases in the future.

Vascular CT and MRI: a practical guide to imaging protocols

Non-invasive cross-sectional imaging techniques play a crucial role in the assessment of the varied manifestations of vascular disease. Vascular imaging encompasses a wide variety of pathology. Designing vascular imaging protocols can be challenging owing to the non-uniform velocity of blood in the aorta, differences in cardiac output between patients, and the effect of different disease states on blood flow. In this review, we provide the rationale behind—and a practical guide to—designing and implementing straightforward vascular computed tomography (CT) and magnetic resonance imaging (MRI) protocols.

Teaching Points

• There is a wide range of vascular pathologies requiring bespoke imaging protocols.

• Variations in cardiac output and non-uniform blood velocity complicate vascular imaging.

• Contrast media dose, injection rate and duration affect arterial enhancement in CTA.

• Iterative CT reconstruction can improve image quality and reduce radiation dose.

• MRA is of particular value when imaging small arteries and venous studies.

The Role of Inferior Vena Cava Filters in Pulmonary Embolism

Pulmonary embolism (PE) is a cause of significant morbidity and mortality, with an estimated 600,000 cases of clinically significant PE in the United States annually, and roughly 200,000 deaths per annum directly attributable to PE. By far the most frequent cause of PE is deep vein thrombosis originating in the lower extremities, which travels to the pulmonary vasculature. The mainstay of treatment is anticoagulation, but multiple additional treatments exist for patients in whom anticoagulation is inadequate or contraindicated. The absolute indications for inferior vena cava (IVC) filtration are narrow, but many filters are placed in patients with relative indications. There is growing concern for overuse of IVC filters, with a relatively low rate of retrieval. It is essential for interventional radiologists to understand the appropriate and correct use and retrieval of IVC filters. Familiarity with placement techniques, protocols and techniques for retrieval, current and emerging technologies, and the clinical model for management of venous thromboembolism, will ensure that interventional radiologists remain an integral member of the care team for these often complex patients.

Catheter-Directed Thrombolysis for Massive Pulmonary Embolism Resulting from Thrombosis in a Duplicated Inferior Vena Cava: A Case Report

Pulmonary embolism (PE) associated with duplicated inferior vena cava (IVC) is rare, and there are no reports of this condition treated with catheter-directed thrombolysis. We present the case of a 54-year-old man who developed massive PE caused by thrombi in a duplicated IVC that detached during transcatheter angiography. After implantation of a retrievable filter in the common IVC, the patient underwent catheter-directed thrombolysis. He was asymptomatic at discharge, with complete resolution of thrombosis and successful retrieval of the filter. The patient had an uneventful 9-month follow-up with no further complications.

Procedural and indwelling complications with inferior vena cava filters: frequency, etiology, and management

Inferior vena cava (IVC) filters are commonly used in select high-risk patients for the prevention of pulmonary embolism. Potentially serious complications can arise from the use of IVC filters, including thrombosis of the filter itself and filter fragment embolization. This article discusses the utility of IVC filters and reviews the management of two cases of filter-related complications.