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6 - Principles of radioembolization
- from Section II - Principles of image-guided therapies
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- By Vanessa L. Gates, Northwestern University, Riad Salem, Northwestern University, Robert J. Lewandowski, Northwestern University
- Edited by Jean-Francois H. Geschwind, Michael C. Soulen
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- Book:
- Interventional Oncology
- Published online:
- 05 September 2016
- Print publication:
- 22 September 2016, pp 44-51
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Summary
Introduction
Radioembolization is defined as the administration of micron-sized embolic particles loaded with a radionuclide using percutaneous transarterial techniques. Fluoroscopic guidance, angiographic endpoints of embolization and stasis, and the need to modify this based on angiographic findings makes this treatment a true embolization procedure. Dosimetry planning, the administration and delivery of radiation on the microscopic level, the modification of the dose based on tumor and hepatic volume, in addition to the required knowledge of radiation effects on tissue make this a brachytherapy procedure. Radioembolization therefore combines radiation with embolization.
Investigations into yttrium-90 (90Y) and other radionuclides as part of a microsphere or particle for the treatment of cancer date back to the 1960s. Initial studies of resin 90Y in humans were reported in the late 1970s. The seminal work in a canine liver model demonstrating the safety and feasibility of using 90Y therapy for hepatic malignancies was reported in the late 1980s. Human studies of 90Y microsphere therapy in liver applications followed from the late 1980s through to the 1990s. These investigations established the safety of 90Y for intrahepatic applications as well as the tolerance of normal parenchyma to radioembolization. It should be noted that different disciplines use slightly different names for radioembolization: microsphere brachytherapy, microbrachytherapy, hepatic intra-arterial radiotherapy, and selective internal radiation therapy. The term radioembolization will be used in this chapter, as it is the preferred term per Society of Interventional Radiology standards document.
Mechanism of radioembolization
Radioembolization of liver tumor takes advantage of the unique vascular system of the liver. In normal liver tissue, approximately 70–80% of the organ's blood flow is supplied by the portal vein, and the hepatic artery accounts for the rest. This contrasts with both hepatocellular carcinoma (HCC) and metastatic tumors to the liver, which have approximately 80–100% of their blood flow supplied by the hepatic artery. This difference in perfusion is exploited by radioembolization, whereby radioactive microspheres doped with a radionuclide are used to produce intentional microembolization of the tumor capillary bed in the liver tumor(s) by delivering the microspheres through the hepatic artery and, subsequently, selectively targeting malignant disease.
14 - 90Yttrium radioembolization for hepatocellular carcinoma
- from Section III - Organ-specific cancers – primary liver cancers
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- By Ryan M. Hickey, Northwestern University, Riad Salem, Hadassah Hebrew University Medical Center, Robert J. Lewandowski, Northwestern University
- Edited by Jean-Francois H. Geschwind, Michael C. Soulen
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- Book:
- Interventional Oncology
- Published online:
- 05 September 2016
- Print publication:
- 22 September 2016, pp 128-133
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Summary
Radioembolization refers to the intra-arterial, transcatheter administration of micrometer-sized particles loaded with a radioisotope, most commonly yttrium-90 (Y90). Because liver tumors derive the majority of their blood supply from hepatic arteries, as opposed to the predominantly portal venous blood supply of normal liver tissue, hepatic arterial injection of Y90-labeled microspheres results in greater deposition of the spheres in tumor tissue as opposed to normal liver parenchyma. Since Y90 radioembolization provides an internal source of radiation to hepatic tumors, it is considered brachytherapy.
Preferential deposition of radioactive microspheres within tumor tissue provides for relative sparing of the uninvolved liver parenchyma from the radiation effects of Y90, thereby permitting significantly higher radiation doses than can be safely administered using external-beam radiation. The radiosensitive nature of normal liver tissue has traditionally limited the role of external-beam radiation in the treatment of primary and metastatic hepatic malignancies, as the incidence of severe radiation-induced liver disease (RILD) may exceed 50% for external-beam radiation doses greater than 35–40 Gy. However, with radioembolization, radiation doses in excess of 150 Gy can be safely administered.
Y90, a pure beta emitter with a half-life of 64.2 hours and tissue penetration of 2.5–11 mm, is incorporated into glass or resin microspheres ranging in size from 20–30 μm (glass) to 20–60 μm (resin). Glass microspheres (Therasphere, BTG International Canada, Ottawa, ON, Canada) were approved in 1999 by the US Food and Drug Administration (FDA) under a Humanitarian Device Exemption for the treatment of unresectable hepatocellular carcinoma (HCC). Resin microspheres (SIR-Spheres, Sirtex Medical, Lane Cove, Australia) were granted full premarketing approval in 2002 by the US FDA for the treatment of unresectable colorectal metastases in conjunction with intrahepatic floxuridine.
Safe and effective treatment of hepatic tumors with radioembolization requires not only the angiographic and endovascular skills critical for selective embolization procedures, but also a comprehensive understanding of radiation administration and safety, including radiation dosimetry and radiation dose modification based on tumor characteristics and a patient's clinical profile.
Patient selection
The patient selection process for Y90 radioembolization involves an assessment of the patient's burden of disease, hepatic biochemical profile, and performance status. Patients should have no extrahepatic disease and a tumor burden less than 70% of the liver volume.
44 - Diagnosis and Management of Superior Vena Cava Syndrome
- from PART IV - SPECIALIZED INTERVENTIONAL TECHNIQUES IN CANCER CARE
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- By Robert J. Lewandowski, Assistant Professor, Department of Radiology Section of Interventional Radiology Robert H. Lurie Comprehensive Cancer Center Northwestern Memorial Hospital Chicago, IL, Bassel Atassi, Research Associate, Department of Radiology Section of Interventional Radiology Robert H. Lurie Comprehensive Cancer Center Northwestern Memorial Hospital Chicago, IL, Riad Salem, Associate Professor, Department of Radiology Robert H. Lurie Comprehensive Cancer Center Northwestern Memorial Hospital Chicago, IL
- Edited by Jean-François H. Geschwind, The Johns Hopkins University School of Medicine, Michael C. Soulen, University of Pennsylvania School of Medicine
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- Book:
- Interventional Oncology
- Published online:
- 18 May 2010
- Print publication:
- 15 September 2008, pp 552-562
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Summary
BACKGROUND
Superior vena cava (SVC) syndrome, first described in 1757 by William Hunter (1), refers to a constellation of clinical symptoms caused by obstruction of the SVC. This obstruction is nearly always (>85%) attributable to advanced malignancy (2, 3), most commonly lung cancer. In fact, SVC syndrome affects 3% to 4% of patients with bronchogenic cancer (4). Other primary thoracic malignancies, lymphoma and metastatic disease (particularly from breast and testicular primaries) have also been implicated in SVC syndrome either secondary to extrinsic compression of the SVC or due to direct tumor invasion (2). Benign causes of SVC syndrome include venous stenoses, thrombosis (secondary to vascular access catheters and invasive monitoring devices), extrinsic compression from thoracic aortic aneurysms and mediastinal fibrosis from granulomatous disease (5).
The diagnosis of SVC syndrome is initially made clinically. SVC syndrome is characterized by congestion and swelling of the face and upper thorax, with distended superficial chest veins. Other associated symptoms include dyspnea, hoarseness, dysphagia, severe headache and cognitive dysfunction (6, 7). The most severe complications of SVC syndrome include glottic edema and venous thrombosis in the central nervous system (venous stroke). Contrast-enhanced computed tomography (CT) of the chest with vascular reconstruction images should be obtained in these patients, as it can both confirm the site of SVC obstruction as well as delineate the cause of the obstruction (8). Alternatively, magnetic resonance imaging (MRI) can be obtained in those patients with contraindications to CT. The gold standard for diagnosing SVC syndrome is venography.
24 - Radioembolization with 90Yttrium Microspheres for Colorectal Liver Metastases
- from PART III - ORGAN-SPECIFIC CANCERS
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- By Bassel Atassi, Research Associate, Department of Radiology Section of Interventional Radiology Robert H. Lurie Comprehensive Cancer Center Northwestern Memorial Hospital Chicago, IL, Saad Ibrahim, Research Fellow, Robert H. Lurie Comprehensive Cancer Center Northwestern Memorial Hospital Chicago, IL, Pankit Parikh, Research Assistant, Northwestern Memorial Hospital Chicago, IL, Robert K. Ryu, Associate Professor, Department of Radiology Northwestern Memorial Hospital Chicago, IL, Kent T. Sato, Assistant Professor, Department of Radiology Northwestern Memorial Hospital Chicago, IL, Robert J. Lewandowski, Assistant Professor, Department of Radiology Section of Interventional Radiology Robert H. Lurie Comprehensive Cancer Center Northwestern Memorial Hospital Chicago, IL, Riad Salem, Associate Professor, Department of Radiology Robert H. Lurie Comprehensive Cancer Center Northwestern Memorial Hospital Chicago, IL
- Edited by Jean-François H. Geschwind, The Johns Hopkins University School of Medicine, Michael C. Soulen, University of Pennsylvania School of Medicine
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- Book:
- Interventional Oncology
- Published online:
- 18 May 2010
- Print publication:
- 15 September 2008, pp 280-289
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Summary
90Yttrium (90Y) microspheres are 20- to 40-μ particles that emit beta radiation. Because the microspheres are delivered via the hepatic arterial route, the process can be considered “internal” rather than external radiation. The treatment algorithm is analogous to that followed with transarterial chemoembolization (TACE). Clinical history, physical examination, laboratory values and performance status are obtained. Patients are initially evaluated and staged using cross-sectional imaging techniques (computerized tomography [CT], magnetic resonance imaging [MRI], positron emission tomography [PET]). Once a patient is considered a possible candidate for therapy, evaluation using mesenteric angiography followed by treatment on a lobar basis is undertaken. Patients are followed clinically to assess toxicities and response prior to proceeding with treatment to the other lobe. A comprehensive review of the technical and methodological considerations in 90Y has been previously published (1–3).
Two devices are commercially available. Thera- Sphere (glass) was approved in 1999 by the Food and Drug Administration (FDA) under a Humanitarian Device Exemption (HDE) for the treatment of unresectable hepatocellular carcinoma (HCC) in patients with or without portal vein thrombosis who can have appropriately positioned hepatic arterial catheters (4). SIR-Spheres (resin) were granted full pre-marketing approval in 2002 by the FDA for the treatment of colorectal metastases in conjunction with intrahepatic floxuridine (FUDR) (5). Both devices have European approval for liver neoplasia and approvals in various Asian countries.
OVERVIEW
Patients with metastatic cancer to the liver from a colorectal primary tumor may be treated using surgical resection alone, providing a chance for long-term cure.