Hemodialysis Access: US for Preprocedural Mapping and Evaluation of Maturity and Access Dysfunction.

Patients with kidney failure require kidney replacement therapy. While renal transplantation remains the treatment of choice for kidney failure, renal replacement therapy with hemodialysis may be required owing to the limited availability and length of time patients may wait for allografts or for patients ineligible for transplant owing to advanced age or comorbidities. The ideal hemodialysis access should provide complication-free dialysis by creating a direct connection between an artery and vein with adequate blood flow that can be reliably and easily accessed percutaneously several times a week. Surgical arteriovenous fistulas and grafts are commonly created for hemodialysis access, with newer techniques that involve the use of minimally invasive endovascular approaches. The emphasis on proactive planning for the placement, protection, and preservation of the next vascular access before the current one fails has increased the use of US for preoperative mapping and monitoring of complications for potential interventions. Preoperative US of the extremity vasculature helps assess anatomic suitability before vascular access creation, increasing the rates of successful maturation. A US mapping protocol ensures reliable measurements and clear communication of anatomic variants that may alter surgical planning. Postoperative imaging helps assess fistula maturation before cannulation for dialysis and evaluates for early and late complications associated with arteriovenous access. Clinical and US findings can suggest developing stenosis that may progress to thrombosis and loss of access function, which can be treated with percutaneous vascular interventions to preserve access patency. Vascular access steal, aneurysms and pseudoaneurysms, and fluid collections are other complications amenable to US evaluation. ©RSNA, 2023 Supplemental material is available for this article. Test Your Knowledge questions for this article are available through the Online Learning Center.

Portal Interventions in the Setting of Venous Thrombosis or Occlusion.

Portal vein thrombosis most commonly occurs as a complication of liver cirrhosis and can result in worsening symptoms of portal hypertension, which often can be challenging to treat with conventional decompression therapies. In addition, because complete portal vein thrombosis is associated with higher posttransplant morbidity and mortality, it is regarded as a relative contraindication to liver transplant. Often, the diagnosis of portal vein thrombosis is incidental; hence, imaging remains the mainstay for diagnosing this complication and is used to guide subsequent treatment. Although anticoagulation is the initial approach used to treat acute portal vein thrombosis, endovascular and/or surgical interventions may be necessary when there is concern for impending bowel ischemia. Treatment of chronic portal vein thrombosis is primarily aimed at alleviating the symptoms of portal hypertension and improving the chance of candidacy for liver transplant. Awareness of the portal venous anatomy to differentiate it from the periportal collaterals is key during recanalization of a chronically occluded portal vein. The authors provide an overview of the pathophysiology, acute and chronic imaging findings, and management of portal vein thrombosis, with a specific focus on endovascular management, as well as a summary of the current related literature. An invited commentary by Lopera and Yamaguchi is available online. ©RSNA, 2022.

Transhepatic inferior vena cava recanalization in a case of Budd Chiari syndrome: A novel approach.

Sharp recanalization for short-segment intravascular occlusion, using an endovascular route, has been described for inferior vena cava (IVC) occlusion. Often, the technical challenge to the endovascular management of Budd-Chiari syndrome (BCS) is the recanalization of the occluded hepatic vein or suprahepatic IVC. Presented here, the challenge was the level of occlusion of the suprahepatic IVC, with the resultant separation of both the patent IVC segments in a horizontal plane, making it technically challenging for sharp recanalization. We describe the use of percutaneous transhepatic access into the suprahepatic IVC via the middle hepatic vein under ultrasound guidance with eventual sharp recanalization of the occluded segment of the IVC, in a woman with BCS. This novel approach has not been described in the literature and can serve as an important addition to guide complex suprahepatic IVC recanalization.

Intrahepatic renal cell carcinoma implantation along a percutaneous biopsy and cryoablation probe tract.

A man in his 60s underwent percutaneous biopsy and cryoablation of a right upper pole clear cell renal cell carcinoma followed by repeat cryoablation 8 months later for possible residual disease. The patient was followed with imaging with documented stability for 19 months after repeat ablation. However, imaging at 32 months demonstrated intrahepatic nodular enhancing lesions along the initial percutaneous biopsy and ablation tract, consistent with metastatic implantation. The patient underwent repeat percutaneous biopsy and two rounds of microwave ablation for treatment of the intrahepatic implants, with no residual disease at 10 months postablation. While needle tract seeding is a known complication of percutaneous manipulation of various abdominopelvic malignancies, there have been no prior reports of intrahepatic metastatic implants related to percutaneous renal cell carcinoma ablation. Awareness of this potential complication is important for treatment planning, informed consent and surveillance. This report shares our experience of the management of intrahepatic metastatic implants.

Radiological correlation of mechanism of intravascular migration of the ventriculoperitoneal shunt and technical considerations for endovascular retrieval.

Migration of ventriculoperitoneal shunt into the pulmonary artery is a rare complication that can lead to shunt malfunction and cardiopulmonary complications. This case illustrates the significance of accidental transvenous placement of the shunt. Identification of the transvenous course of the catheter on cross sectional imaging can predict future catheter migration and also aid at surgical extraction. Formation of knot within the distal portion of the shunt catheter during migration or endovascular retrieval can occur, therefore measures to retrieve with knot and adhesions should be factored in before.

Percutaneous Hepaticojejunostomy Using a Radiofrequency Wire for Management of a Postoperative Bile Leak.

Postoperative biliary complications following extensive hepatic resections are complex, often requiring a multidisciplinary team approach. We describe a case of a free bile duct leak following extended right hepatectomy and surgical hepaticojejunostomy treated with percutaneous transhepatic hepaticojejunostomy in which a radiofrequency guidewire was used to gain enteral access. A modified internal/external biliary catheter was left in place. The patient was enrolled in a benign biliary stricture protocol, and 8 months later, the catheter was removed following a normal cholangiogram and biliary manometric perfusion testing. At 3-month follow-up after catheter removal, the patient is asymptomatic with no clinical, biochemical, or radiographic evidence of biliary leak or obstruction.