Therapeutic angiogenesis: the next frontier for interventional radiology

The field of interventional radiology has traditionally relied on mechanical methods to treat vascular disease, such as angioplasty balloons and stents. Although there have been a number of important technical advances in endovascular devices, there are still a number of patients who are not candidates for percutaneous or surgical revascularization. As we approach the technical limits of these newer devices, therapeutic angiogenesis may play an ever-increasing role in the future. Interventional radiologists have unique delivery skills that would complement the on-going research in this area. It is the goal of this article to serve as a primer for interventional radiologists on the agents and techniques used in this exciting field.     

Targeted drug delivery under MRI guidance

The main goal of local drug delivery is to increase the concentration of a specific therapeutic agent in a target tissue with minimal nontarget distribution. Compared to systemic therapy, local drug delivery provides a high level of therapeutic efficacy with minimal systemic effects. The current primary imaging modality for drug delivery has been x-ray angiography, but it has major limitations including anatomical ambiguity and inability to visualize the targeted tissues. Due to these inherent problems, MR guidance has been explored as an alternative imaging modality for guiding and monitoring of drug therapy. Recently, interventional MR (XMR) systems have been implemented that have both dual x-ray and MRI capabilities in a single suite and allow for real-time interventional procedures to be performed in a clinical setting. In cases where drug delivery is required, this system provides a significant leap for catheter-based therapies. Although clinical drug delivery procedures utilizing MR guidance are still in the early stages of development and application, recent technological advances should help further promote the adoption of such procedures. This review covers the emerging techniques of drug delivery using MR guidance.     

CT findings of chemotherapy-induced toxicity: what radiologists need to know about the clinical and radiologic manifestations of chemotherapy toxicity

Cancer chemotherapy has evolved from cytotoxic agents and now includes several new agents that target specific molecules responsible for the regulation of cell growth, nutrient supply, and differentiation. These molecularly targeted therapies have a different mechanism of action than do classic cytotoxic agents, which predominantly attack rapidly proliferating cells. Not surprisingly, therefore, the toxicity of targeted and cytotoxic agents may differ in both clinical and radiologic presentation. Many of the toxicities of targeted therapies are not cumulative or dose dependent, some are asymptomatic, and others may first manifest radiologically. It is imperative that radiologists be aware of these toxicities and that they learn to recognize the relevant findings so that they can provide a complete differential diagnosis and thus play an important role in patient care.     

Principles and techniques of transcatheter embolotherapy for peripheral vascular lesions

Transcatheter embolotherapy (TCE), a common procedure for interventional radiologists, comprises transcatheter delivery of embolic agents into target vessels in order to eliminate lesions or lesion-associated symptoms. Good knowledge of delivery catheters and embolic agents is essential to optimize embolization techniques and to obtain the desired therapeutic outcomes. In this review, we describe the principles and techniques of TCE for peripheral arterial and venous lesions featuring visceral aneurysms, peripheral and pulmonary arteriovenous malformations (AVMs), and varicoceles. This work was presented as an educational lecture at the 64^th JRS meeting (April 2005) in Yokohama.     

Update on anticoagulant medications for the interventional radiologist

For many years, available anticoagulant medications were limited to vitamin K antagonists, unfractionated heparin, and aspirin. However, in the past 20 years, several new agents have been developed for the treatment of thrombosis, and even more are being developed. This increasing number of medications has led to more specific treatment algorithms for the care of venous and arterial thrombotic events. As more agents become available, treatment guidelines are rapidly changing. With increasing frequency, interventional radiologists encounter patients already taking anticoagulant medications prophylactically or therapeutically, or they need to determine which anticoagulant medications need to be initiated for a particular procedure. Therefore, it has become increasingly important to understand the mechanisms, risks, and benefits of anticoagulant medications. A review of the traditional anticoagulants, their new counterparts, and their places in the medication repertoire of interventional radiology will be discussed herein.     

The acquisition of skills in interventional radiology by supervised training on animal models: A three-year multicenter experience

Conclusions These training courses, which have been going on for 3 years, have shown us that using an animal model for such training is an efficient way to teach the techniques. All radiology departments with animal research facilities can make use of this approach to train their own interventional radiologists and to assist in training those from institutions without such facilities.By refining our techniques we hope to reduce the high complication rate that inevitably accompanies the initial performance of new procedures. Moreover, clinicians will gain confidence in the ability of radiologists.Our courses have provided young radiologists with the opportunity to learn new techniques and improve their skills in interventional techniques. Once resistance to the use of animals for training is overcome, these physicians can be more actively involved in starting projects on their own and will feel encouraged to do so.     

Nanotechnology and its Relationship to Interventional Radiology. Part II: Drug Delivery, Thermotherapy, and Vascular Intervention

Nanotechnology can be defined as the design, creation, and manipulation of structures on the nanometer scale. This two-part review is intended to acquaint the interventionalist with the field of nanotechnology, and provide an overview of potential applications, while highlighting advances relevant to interventional radiology. Part 2 of the article concentrates on drug delivery, thermotherapy, and vascular intervention. In oncology, advances in drug delivery allow for improved efficacy, decreased toxicity, and greater potential for targeted therapy. Magnetic nanoparticles show potential for use in thermotherapy treatments of various tumours, and the effectiveness of radiofrequency ablation can be enhanced with nanoparticle chemotherapy agents. In vascular intervention, much work is focused on prevention of restenosis through developments in stent technology and systems for localised drug delivery to vessel walls. Further areas of interest include applications for thrombolysis and haemostasis.     

Continuous infusion with implantable pumps: expanding the radiologist's role

Drug infusion systems attract increasing attention as biomedical technology offers miniaturized devices for targeted delivery of therapeutic substances on an outpatient basis. We have used a totally implantable, subcutaneous pump, externally programmable by radiofrequency link, learning the technique of implantation and management and using various imaging modalities for the diagnosis and control of complications. The procedure for implanting systems for continuous intrathecal analgesia and systemic intravenous chemotherapy is described. Our experience of the latter is made up of 296 implants in 290 patients. The selected infusion pump proved reliable and acceptable to patients and the quality of life, given the reduced drug toxicity, more than good. The complications were few both in frequency and in severity. The setting-up of a long-term infusion system, when major surgery is not needed, can fall within the interventional radiologist's field, partly because of a good cost-benefit ratio.     

Nanotechnology development and utilization: a primer for diagnostic and interventional radiologists

The term nanotechnology refers to the design, creation, and manipulation of structures on the nanometer scale. Much of the ongoing research and development of nanotechnology is focused on the development of novel methods of imaging and delivery of therapeutics through minimally invasive means. Multifunctional nanoparticles offer great promise for molecular imaging and directing novel therapeutics to molecular targets, which was never before possible. Nanoparticle-based contrast agents have been developed for all imaging modalities. A rapidly increasing number of companies and government funding initiatives have led to a large number of novel agents in various stages of development, ranging from in vitro and in vivo animal studies to clinical use. However, barriers to the delivery of nanoparticles for tumor imaging and therapy exist. Interventional radiologists may circumvent these barriers by using imaging to guide delivery of nanoparticles.     

Postprocedure clinical management for the interventional radiologist

Interventional procedures for oncology patients are being used more frequently in the front line and palliative setting. It is important that interventional radiologists familiarize themselves with some of the frequently encountered symptoms and potential complications and develop guidelines to help manage and sometimes prevent these complications from occurring. Unfortunately, there is not much data to support various supportive measures specifically for the post-procedural patient. However, by extrapolating the information available for the management of systemic chemotherapy patients, as well as discussing the steps that can be taken to avoid certain complications like acute renal failure, we as oncologists and interventional radiologists can better care for this unique and often complicated patient population.     

Percutaneous Catheter and Port Placement for Hepatic Arterial Infusion Chemotherapy: Catheter Placement from Subclavian Artery

Hepatic arterial infusion chemotherapy (HAIC) has been performed for patients with life-threatening liver tumors resistant to standard therapies for more than 30 years. Placement of the port and catheter system for HAIC is performed by surgeons or interventional radiologists. Surgical placement requires laparotomy, whereas the interventional radiologic approach places a port and a catheter percutaneously. The interventional radiologic technique of implanting a port and catheter was originally developed in Japan in the 1980s. The procedure consists of arterial redistribution, catheter and port placement, and evaluation and management of the drug distribution. For the catheter and port placement, the subclavian artery, femoral artery, or inferior epigastric artery is used as an access route. We have used a subclavian artery for HAIC to have the stability of the system at the anterior chest wall and the ease to advance a catheter into hepatic arteries at the time of the placement; however, there are some risks, such as cerebral infarction, and the specific skills of a cutdown procedure are required to access the subclavian artery. No procedure can be perfectly appropriate for all patients, and we should consider what we choose on a case-by-case basis. With this video (available online at www.jvir.org), we hope many interventional radiologists will be aware that this could be within their scope of practice with training.     

Hemodialysis catheter placement and management

Hemodialysis catheters are an integral part of the delivery of hemodialysis. While catheters play an important role in the patient undergoing hemodialysis, catheters should be considered a bridge to more permanent forms of dialysis access in most patients. Recent advances in catheter technology, access techniques, and choice of access sites have improved outcomes associated with hemodialysis catheters. The placement and management of hemodialysis catheters by interventional radiologists have played an important role in these advances, and interventional radiologists are taking an increasingly active role in the research and development of catheters and catheter insertion techniques. The present status of hemodialysis catheters is reviewed.     

A portrait of interventional radiologists in the United States

OBJECTIVE: In recognition of the emergence of interventional radiology as an important "new component of...radiology," the objective of our study was to provide an extensive and detailed portrait of interventional radiologists, their professional activities, and the practices in which they work. MATERIALS AND METHODS: We tabulated data from the American College of Radiology's 2003 Survey of Radiologists, a stratified random-sample survey that oversampled interventionalists and achieved a 63% response rate with a total of 1,924 responses. Responses were weighted to make them representative of all radiologists in the United States. We compared information about interventionalists with that for other radiologists. RESULTS: Depending on the definition of who is an interventionalist, 8.5-11.5% of radiologists are interventionalists. By most definitions, only slightly under half of interventionalists spend 70% or more of their clinical work time performing interventional procedures. Interventionalists work, on average, 56-58 hr weekly, a few hours longer than other radiologists. The average interventionalist performs procedures in five of the seven categories of procedures into which we divided interventional radiology, compared with one or two categories for other radiologists. The average interventionalist performs procedures in five of the seven broad categories (such as MRI, CT, and nuclear medicine) into which we divided all of radiology, much the same breadth of practice as other subspecialists and also as nonsubspecialists. CONCLUSION: Interventionalists have become a sizable group within radiology. They are in some ways like other radiologists and in other ways different, but they do not spend as much of their time in their subspecialty as some assume and, overall, are not as different.     

Decade of molecular targeted therapy: abdominal manifestations of drug toxicities--what radiologists should know

OBJECTIVE: Novel drugs targeting molecular pathways involved in tumor development have revolutionized cancer treatment. Radiologists often focus on therapeutic response when evaluating cancer patients and may miss important signs of drug toxicity. This article familiarizes radiologists with the complications of molecular targeted agents in abdominal solid organs, enabling early identification and appropriate intervention and thus reducing patient morbidity and mortality. CONCLUSION: Knowledge of the common abdominal toxicities--including hepatitis, cholecystitis, pancreatitis, fluid retention, and infection--is crucial for early diagnosis, which may spare patients devastating complications or the need for surgery.     

围肝移植并发症介入治疗的认识

大部分肝移植术后并发症与介入放射学有关.动脉和静脉并发症有较明确的介入治疗模式,胆道并发症一直是治疗的重点和难点.随着对介入放射学认识的深入和操作技术的提高,在经皮经肝胆道引流、内镜鼻胆管引流基础上围绕胆道并发症进行的系列治疗,能解决部分患者的黄疸并最终治愈,但对另一些患者胆道引流仍是主要的姑息性治疗手段,并将最终伴随患者一生.围绕胆道并发症制订肝移植术后并发症的临床治疗指引是亟需解决的课题.     

Periprocedural management of hemostasis risk in interventional radiology

Given the increasing demand for interventional image-guided procedures, radiologists are increasingly sollicited by clinicians to participate in the management of patients prior to and after the interventional procedure, especially with regards to hemostasis. Therefore, radiologists should be familiar with the risk of procedure related hemorrhage. Based on consensus guidelines published by the Society of Interventional Radiology (SIR), the risk of hemorrhage for each interventional procedure will be classified. Recommendations for preprocedure testing based on the type of procedure planned will be reviewed. Finally, limitations of hemostasis parameters will be discussed along with management of anticoagulants and antiplatelet agents before the procedure.     

Circulating Tumor Cells: Personalized Medicine in Interventional Oncology?

Innovative technologic advancements have expanded the ability of interventional radiologists to capture and visualize directly tumor cells that have intravasated into the circulation. The detection of these circulating tumor cells (CTCs) is revolutionizing the understanding of the pathogenesis of metastasis and is paving the way for exquisitely sensitive techniques to detect malignancy, monitor recurrence, and prognosticate outcomes. In this review, the prevailing theories on the pathobiology of metastasis and the tools that have been developed to investigate CTCs are summarized. The tremendous impact CTCs are likely to have in oncology is discussed, with particular emphasis on their relevance to interventional oncology.     

Value of MR contrast media in image-guided body interventions

In the past few years,there have been multiple advances in magnetic resonance (MR) instrumentation,in vivo devices,real-time imaging sequences and interventional procedures with new therapies.More recently,interventionists have started to use minimally invasive image-guided procedures and local therapies,which reduce the pain from conventional surgery and increase drug effectiveness,respectively.Local therapy also reduces the systemic dose and eliminates the toxic side effects of some drugs to other organs.The success of MR-guided procedures depends on visualization of the targets in 3D and precise deployment of ablation catheters,local therapies and devices.MR contrast media provide a wealth of tissue contrast and allows 3D and 4D image acquisitions.After the development of fast imaging sequences,the clinical applications of MR contrast media have been substantially expanded to include pre-during-and post-interventions.Prior to intervention,MR contrast media have the potential to localize and delineate pathologic tissues of vital organs,such as the brain,heart,breast,kidney,prostate,liver and uterus.They also offer other options such as labeling therapeutic agents or cells.During intervention,these agents have the capability to map blood vessels and enhance the contrast between the endovascular guidewire/catheters/devices,blood and tissues as well as direct therapies to the target.Furthermore,labeling therapeutic agents or cells aids in visualizing their delivery sites and tracking their tissue distribution.After intervention,MR contrast media have been used for assessing the efficacy of ablation and therapies.It should be noted that most image-guided procedures are under preclinical research and development.It can be concluded that MR contrast media have great value in preclinical and some clinical interventional procedures.Future applications of MR contrast media in image-guided procedures depend on their safety,tolerability,tissue specificity and effectiveness in demonstrating success of the interventions and therapies.     

介入放射学研究生教学改革初探

目前介入放射学研究生教学存在教育质量下降、高端人才流失等问题,本文就介入放射学研究生教学的现状和存在问题及原因进行剖析,并就如何培养综合素质高、迎合学科发展的研究生人才队伍进行初步探讨。     

Bronchial and nonbronchial systemic artery embolization for life-threatening hemoptysis: a comprehensive review.

Massive hemoptysis is one of the most dreaded of all respiratory emergencies and can have a variety of underlying causes. In 90% of cases, the source of massive hemoptysis is the bronchial circulation. Diagnostic studies for massive hemoptysis include radiography, bronchoscopy, and computed tomography (CT) of the chest. Bronchoscopy and chest radiography have been considered the primary methods for the diagnosis and localization of hemoptysis. Many researchers currently suggest that CT should be performed prior to bronchoscopy in all cases of massive hemoptysis. Bronchial artery embolization (BAE) is a safe and effective nonsurgical treatment for patients with massive hemoptysis. However, nonbronchial systemic arteries can be a significant source of massive hemoptysis and a cause of recurrence after successful BAE. Knowledge of the bronchial artery anatomy, together with an understanding of the pathophysiologic features of massive hemoptysis, are essential for planning and performing BAE in affected patients. In addition, interventional radiologists should be familiar with the techniques, results, and possible complications of BAE and with the characteristics of the various embolic agents used in the procedure.