Sandeep Vaidya

An Overview of Embolic Agents

Therapeutic embolization is a common procedure in interventional radiology. A wide variety of agents are available, and each has its own place and use. Additionally, many new agents have appeared on the market in the past several years. The aim of this review article is to give a brief description of available agents, guide appropriate selection, and familiarize the reader regarding appropriate use and limitations.

Imaging in Pregnant Patients: Examination Appropriateness

A recurring source of contention between clinicians and radiologists continues to be examination appropriateness when imaging pregnant patients. With the multitude of references on potential radiation risks to the fetus, radiologists tend to be cautious and hesitant about exposing the fetus to radiation. This tendency is often interpreted by referring physicians as intrusion into and delay in the care of their patients. The risk burden of radiation exposure to the fetus has to be carefully weighed against the benefits of obtaining a critical diagnosis quickly and using a single tailored imaging study. In general, there is lower than expected awareness of radiation risks to the fetus from imaging pregnant patients. Modalities that do not use ionizing radiation, such as ultrasonography and magnetic resonance imaging, should be the preferred examinations for evaluating an acute condition in a pregnant patient. However, no examination should be withheld when an important clinical diagnosis is under consideration. Exposure to ionizing radiation may be unavoidable, but there is no evidence to suggest that the risk to the fetus after a single imaging study and an interventional procedure is significant. All efforts should be made to minimize the exposure, with consideration of the risk versus benefit for a given clinical scenario.

Safety and Efficacy of Drug-eluting Bead Chemoembolization for Hepatocellular Carcinoma: Comparison of Small-versus Medium-size Particles

PURPOSE To compare safety and imaging response with 100-300 μm and 300-500 μm doxorubicin drug-eluting bead (DEBs) to determine optimal particle size for chemoembolization of hepatocellular carcinoma (HCC). MATERIALS AND METHODS DEB chemoembolization using 100-300 μm (n = 39) or 300-500 μm (n = 22) LC beads loaded with 50 mg of doxorubicin was performed in 61 patients with HCC. Patient age, sex, etiology of liver disease, degree of underlying liver disease, tumor burden, and performance status were similar between the groups. All treatments were performed in a single session and represented the patients first treatment. Toxicities and imaging response in a single index tumor were analyzed using World Health Organization (WHO) and European Association for the Study of the Liver (EASL) criteria. RESULTS There was a significantly lower incidence of postembolization syndrome and fatigue after treatment in the 100-300 μm group (8% and 36%) versus the 300-500 μm group (40% and 70%) (100-300 μm group, P = .011; 300-500 μm group, P = .025). Mean change in tumor size was similar between the two groups based on WHO and EASL criteria and similar rates of objective response, but there was a trend toward a higher incidence of EASL complete response with 100-300 μm beads versus 300-500 μm beads (59% vs 36%; P = .114). CONCLUSIONS In DEB chemoembolization for treatment of HCC, 100-300 μm doxorubicin DEBs are favored over 300-500 μm doxorubicin DEBs because of lower rates of toxicity after treatment and a trend toward more complete imaging response at initial follow-up.

Liver transplantation: vascular complications.

Transplantation has become the method of choice for treatment of patients with irreversible severe liver dysfunction. Vascular thrombosis or stenosis, biliary obstruction, hemorrhage, posttransplantation neoplasm, and rejection are some of the most common potential complications. Most complications cause significant morbidity and mortality after liver transplantation. The appearance of vascular complications in posttransplantation patients is illustrated in this article.

Cerebral Aneurysms Treated with Flow-Diverting Stents: Computational Models with Intravascular Blood Flow Measurements

BACKGROUND AND PURPOSE: Computational fluid dynamics modeling is useful in the study of the hemodynamic environment of cerebral aneurysms, but patient-specific measurements of boundary conditions, such as blood flow velocity and pressure, have not been previously applied to the study of flow-diverting stents. We integrated patient-specific intravascular blood flow velocity and pressure measurements into computational models of aneurysms before and after treatment with flow-diverting stents to determine stent effects on aneurysm hemodynamics. MATERIALS AND METHODS: Blood flow velocity and pressure were measured in peri-aneurysmal locations by use of an intravascular dual-sensor pressure and Doppler velocity guidewire before and after flow-diverting stent treatment of 4 unruptured cerebral aneurysms. These measurements defined inflow and outflow boundary conditions for computational models. Intra-aneurysmal flow rates, wall shear stress, and wall shear stress gradient were calculated. RESULTS: Measurements of inflow velocity and outflow pressure were successful in all 4 patients. Computational models incorporating these measurements demonstrated significant reductions in intra-aneurysmal wall shear stress and wall shear stress gradient and a trend in reduced intra-aneurysmal blood flow. CONCLUSIONS: Integration of intravascular dual-sensor guidewire measurements of blood flow velocity and blood pressure provided patient-specific computational models of cerebral aneurysms. Aneurysm treatment with flow-diverting stents reduces blood flow and hemodynamic shear stress in the aneurysm dome.

Spontaneous celiac artery dissection and its management.

Spontaneous visceral artery dissection is an uncommon event with an unpredictable natural history with superior mesenteric artery being the most common affected artery. It is most often asymptomatic and usually diagnosed at autopsy. Pre-disposing factors are not specific but have been suggested to be pre-existing vascular disease, hypertension and pregnancy. Spontaneous resolution, definitive occlusion of the artery, and formation of an aneurysm with associated complications are some other possible outcomes. Isolated dissection of the celiac artery (CA) is rare and there are only a few cases reported in the literature. We present a case of a 65 year old male with spontaneous celiac artery dissection and provide a review of the current literature about imaging findings and management of this entity.

Comparison of Positron Emission Tomography and Bremsstrahlung Imaging to Detect Particle Distribution in Patients Undergoing Yttrium-90 Radioembolization for Large Hepatocellular Carcinomas or Associated Portal Vein Thrombosis

PURPOSE To compare positron emission tomography/computed tomography (PET/CT) imaging with bremsstrahlung single photon emission computed tomography (SPECT) in patients after yttrium-90 ((90)Y) microsphere radioembolization to assess particle uptake. MATERIALS AND METHODS This prospective study comprised patients with large (> 5 cm) hepatocellular carcinoma (HCC) or tumor-associated portal vein thrombus (PVT), or both. After radioembolization for HCC, patients underwent bremsstrahlung SPECT/CT and time-of-flight PET/CT imaging of (90)Y without additional tracer administration. Follow-up imaging and toxicity was analyzed. Imaging analyses of PET/CT and bremsstrahlung SPECT/CT were independently performed. RESULTS There were 13 patients enrolled in the study, including 7 with PVT. Median tumor diameter was 7 cm. PET/CT demonstrated precise localization of (90)Y particles in the liver, with specific patterns of uptake in large tumors. In cases of PVT, PET/CT showed activity within the PVT. When correlated to short-term follow-up imaging, areas of necrosis correlated with regions of uptake seen on PET/CT. Compared with bremsstrahlung imaging, PET/CT demonstrated at least comparable spatial resolution with less scatter. Quantitative uptake in nontreated regions of interest showed significantly reduced scatter with PET/CT versus SPECT/CT (1% vs 14%, P < .001). CONCLUSIONS Evaluation of (90)Y particle uptake with PET/CT potentially demonstrates high spatial resolution and low scatter compared with bremsstrahlung SPECT/CT. Confirmation of particles within PVT on PET/CT correlates with response on follow-up imaging and may account for the efficacy of radioembolization in patients with PVT.

Imaging of orthotopic liver transplantation: review.

Received September 23, 2010; accepted without revision September 23, 2010. 1Department of Radiology, University of Washington, VA Puget Sound Health Care System, 1660 S Columbian Way, S-114/Radiology, Mail Stop 358280, Seattle, WA 98108. Address correspondence to P. Bhargava (bhargp@u.washington.edu). 2Department of Radiology, University of Washington, Seattle, WA. 3Department of Surgery, University of Washington, Seattle, WA. AJR 2011;196:WS15–WS25 0361–803X/11/1963–S1

Midterm follow-up of transjugular intrahepatic portosystemic shunts using polytetrafluoroethylene endografts in children

PURPOSE To report the initial experience of a pediatric centers use of expanded polytetrafluoroethylene (ePTFE) endografts for the creation of transjugular intrahepatic portosystemic shunts (TIPSs) in children. MATERIALS AND METHODS Twelve consecutive patients had a TIPS created, all with ePTFE endografts. Nine were children younger than 18 years of age: one infant (age 18 mo) and eight adolescent children with a median age of 14 years, 3 months (range, 10 y, 1 mo, to 17 y, 2 mo). All had gastric or esophageal varices. Acute variceal bleeding was the primary indication in four of nine cases (44%). Mean follow-up was 20 months (range, 4 d to 32 mo). RESULTS Technical success rate was 100%. Seven TIPSs (78%) were created with a 10-mm-diameter endograft and two (22%) were created with an 8-mm-diameter endograft. Mean portosystemic gradient was reduced from 15.9 mm Hg to 5.8 mm Hg after TIPS creation. The devices were not dilated to their nominal diameter in seven of nine cases (78%). There were no major complications or mortalities associated with TIPS creation. There was one minor complication during follow-up in which a child developed progressively increasing lethargy. Primary patency rate by ultrasound during follow-up was 100%. There were no shunt dysfunctions or repeat interventions required, and no clinical recurrences. One child received a liver transplant 4 days after TIPS creation. CONCLUSIONS TIPSs can be created in children with the use of ePTFE endografts with an excellent midterm primary patency rate and a low complication rate.

Surgical Resection of a Malignant Liver Lesion: What the Surgeon Wants the Radiologist to Know

OBJECTIVE Hepatic malignancy is a common and lethal disease, whether due to a primary tumor or metastasis. There are numerous treatment options available depending on the stage of the disease and medical condition of the patient, including systemic chemotherapy, transcatheter embolization, thermal ablation, and surgical resection. In a subset of patients with liver malignancy, surgical resection can offer the best chance of long-term survival and potentially even cure. This article reviews the major indications and contraindications for resection, basic surgical techniques and terminology, key clinical and imaging preoperative workup, and pertinent interventional oncology procedures in the management of hepatic malignancy. CONCLUSION Diagnostic and interventional radiology plays an important role in the assessment and treatment of malignant hepatic lesions. Radiologists should be familiar with how surgeons select, work up, and treat candidates for liver resection to provide the most clinically valuable service.