Endovascular and interventional procedures in obese patients: a review of procedural technique modifications and radiation management

Radiation Exposure and Safety Considerations in Interventional Radiology: Comparison of a Twin Robotic X-ray System to a Conventional Angiography System

Background/Objectives: To evaluate radiation exposure in standard interventional radiology procedures using a twin robotic X-ray system compared to a state-of-the-art conventional angiography system. Methods: Standard interventional radiology procedures (port implantation, SIRT, and pelvic angiography) were simulated using an anthropomorphic Alderson RANDO phantom (Alderson Research Laboratories Inc. Stamford, CT, USA) on an above-the-table twin robotic X-ray scanner (Multitom Rax, Siemens Healthineers, Forchheim, Germany) and a conventional below-the-table angiography system (Artis Zeego, Siemens Healthineers, Forchheim, Germany). The phantom's radiation exposure (representing the potential patient on the procedure table) was measured with thermoluminescent dosimeters. Height-dependent dose curves were generated for examiners and radiation technologists in representative positions using a RaySafe X2 system (RaySafe, Billdal, Sweden). Results: For all scenarios, the device-specific dose distribution differs depending on the imaging chain, with specific advantages and disadvantages. Radiation exposure for the patient is significantly increased when using the Multitom Rax for pelvic angiography compared to the Artis Zeego, which is evident in the dose progression through the phantom's body as well as in the organ-related radiation exposure. In line with these findings, there is an increased radiation exposure for the performing proceduralist, especially at eye level, which can be significantly minimized by using protective equipment (p < 0.001). Conclusions: In this study, the state-of-the-art conventional below-the-table angiography system is associated with lower radiation dose exposures for both the patient and the interventional radiology physician compared to an above-the-table twin robotic X-ray system for pelvic angiographies. However, in other clinical scenarios (port implantation or SIRT), both devices are suitable options with acceptable radiation exposure.

Physician impact on use of fluoroscopy during endovascular procedures to improve radiation safety

OBJECTIVE

To determine whether differences exist in fluoroscopy time and radiation exposure during lower extremity endovascular procedures performed by fellowship trained vascular surgeons vs general surgeons, to minimize radiation exposure to operating room staff.

METHODS

A retrospective review of all lower extremity endovascular procedures was performed from August 1, 2014, to January 29, 2016. The procedures were performed by the surgical department's four surgeons with endovascular privileges: two vascular surgeons and two general surgeons. Only procedures involving lower extremity arterial angiograms with balloon angioplasty, stenting, or atherectomy were included. The operative records were reviewed for each case. The total fluoroscopy time and total radiation dose for each procedure were recorded. Procedures were grouped according to the number of endovascular interventions as one to two interventions, three to four interventions, and five or more interventions performed. Statistical analysis was performed with a P value of less than .05 considered significant.

RESULTS

About 271 lower extremity endovascular procedures were performed during the study period by 4 surgeons. The average age of the patient population was 70 years. The total number of procedures performed over the study period were 112, 45, 91, and 25 for surgeons 1 through 4, respectively. On average, 3.24 interventions were performed during each procedure. Vascular surgeons were found to have shorter fluoroscopy time for procedures involving one to two (7.8 vs 30.1; P < .01), three to four (9.3 vs 34.2; P < .01), and five or more (11.5 vs 51.9; P < .01) interventions. Vascular surgeons were also found to have less radiation exposure compared with general surgeons in procedures with one to two (1.69 vs 3.53; P = .001) and five or more (2.3 vs 5.4; P = .003) interventions. There was no significant difference in radiation exposure between vascular and general surgeons for procedures with three to four interventions (5.86 vs 5.59; P = .95).

CONCLUSIONS

In this small series at our institution, lower extremity endovascular procedures performed by specialty trained vascular surgeons were associated with both decreased operative fluoroscopy time and decreased radiation exposure when compared with general surgeons.

High-Dose Fluoroscopically Guided Procedures in Patients: Radiation Management Recommendations for Interventionalists

The article is part of the series of articles on radiation protection. You can find further articles in the special section of the CVIR issue. In addition to the risks from fluoroscopic-guided interventional procedures of tissue injuries, recent studies have drawn attention to the risk of stochastic effects. Guidelines exist for preprocedural planning and radiation management during the procedure. The concept of a substantial radiation dose level (SRDL) is helpful for patient follow-up for tissue injury. The uncommon nature of tissue injuries requires the interventionalist to be responsible for follow-up of patients who receive substantial radiation doses. Dose management systems for recognizing and avoiding higher patient exposures have been introduced. The European Directive provides a legal framework and requirements for equipment, training, dose monitoring, recording and optimization that are helpful in radiation risk management.

Technical challenges of imaging & image-guided interventions in obese patients

Obese patients challenge imaging departments in their ability to obtain diagnostic quality images and to perform image-guided interventions. These technical challenges include properly accommodating large patients on imaging equipment, adjusting equipment settings to address imaging limitations, and pre-planning and preparation for image-guided interventions to insure safe and successful outcomes. Knowing and addressing these challenges can result in successfully addressing the imaging and image-guided interventions needs of obese patients.

Optimizing care for the obese patient in interventional radiology

With the rising epidemic of obesity, interventional radiologists are treating increasing numbers of obese patients, as comorbidities associated with obesity preclude more invasive treatments. These patients are at heightened risk of vascular and oncologic disease, both of which often require interventional radiology care. Obese patients pose unique challenges in imaging, technical feasibility, and periprocedural monitoring. This review describes the technical and clinical challenges posed by this population, with proposed methods to mitigate these challenges and optimize care.

The Effect of a New Angiographic Imaging Technology on Radiation Dose in Visceral Embolization Procedures

PURPOSE

To evaluate the impact of a new angiographic imaging technology on radiation dose during visceral embolization procedures involving both fluoroscopy and digital subtraction angiography.

MATERIAL AND METHODS

A retrospective analysis from a single-center consecutive series of patients was performed comparing 2 angiographic imaging systems. The AlluraClarity (CIQ; Philips Healthcare, Best, the Netherlands) was used in 100 patients (n = 59 male, mean age: 70.6 years) from July 2013 to April 2014 and compared to the former AlluraXper (AX) technology used in 139 patients (n = 71 male, mean age: 70.1 years) from May 2011 to June 2013. Patients were categorized according to body mass index (BMI [kg/m²])-group 1: BMI <25, group 2: BMI ≥25 and <30, and group 3: BMI ≥30. Fluoroscopy time, the total dose of iodinated contrast administered, and procedural AirKerma (Ka, r [mGy]) were obtained.

RESULTS

Mean BMI was 26.4 ± 5.0 kg/m² in the CIQ and 26.4 ± 7.1 kg/m² in the AX group ( P = .93). Fluoroscopy time and the amount of contrast media were equally distributed. Ka, r was 1342.9 mGy versus 2214.8 mGy ( P < .001, t test) when comparing CIQ to AX. Comparing CIQ to AX, BMI subgroup analysis revealed a mean Ka, r of 970.1 to 1586.1 mGy ( P = .003, t test), 1484.7 to 2170.1 mGy ( P = .02, t test), and 1848.8 to 3348.9 mGy ( P = .001, t test) in BMI groups 1, 2, and 3, respectively.

CONCLUSION

The CIQ technology significantly reduced mean radiation dose by 39.4% for visceral embolization procedures when compared to fluoroscopy time and contrast media dose. This dose relationship was consistent across all BMI groups.

Unintended and accidental medical radiation exposures in radiology: guidelines on investigation and prevention

This paper sets out guidelines for managing radiation exposure incidents involving patients in diagnostic and interventional radiology. The work is based on collation of experiences from representatives of international and national organizations for radiologists, medical physicists, radiographers, regulators, and equipment manufacturers, derived from an International Atomic Energy Agency Technical Meeting. More serious overexposures can result in skin doses high enough to produce tissue reactions, in interventional procedures and computed tomography, most notably from perfusion studies. A major factor involved has been deficiencies in training of staff in operation of equipment and optimization techniques. The use of checklists and time outs before procedures commence, and dose alerts when critical levels are reached during procedures, can provide safeguards to reduce the risks of these effects occurring. However, unintended and accidental overexposures resulting in relatively small additional doses can take place in any diagnostic or interventional x-ray procedure and it is important to learn from errors that occur, as these may lead to increased risks of stochastic effects. Such events may involve the wrong examinations, procedural errors, or equipment faults. Guidance is given on prevention, investigation, and dose calculation for radiology exposure incidents within healthcare facilities. Responsibilities should be clearly set out in formal policies, and procedures should be in place to ensure that root causes are identified and deficiencies addressed. When an overexposure of a patient or an unintended exposure of a foetus occurs, the foetal, organ, skin, and/or effective dose may be estimated from exposure data. When doses are very low, generic values for the examination may be sufficient, but a full assessment of doses to all exposed organs and tissues may sometimes be required. The use of general terminology to describe risks from stochastic effects is recommended rather than the calculation of numerical values, as these are misleading when applied to individuals.

Transradial access for visceral endovascular interventions in morbidly obese patients: safety and feasibility

PURPOSE

Transradial access (TRA) has been shown to lower morbidity and bleeding complications compared to transfemoral access in percutaneous coronary interventions. Morbid obesity, commonly defined as a body mass index (BMI) ≥40 kg/m2, has been shown to be a risk factor for access site complications irrespective of access site. This study evaluates the safety and feasibility of performing visceral endovascular interventions in morbidly obese patients via TRA.

METHODS

Procedural details, technical success, and 30-day major and minor access site, bleeding, and neurological adverse events were prospectively recorded in a database of 1057 procedures performed via the radial artery. From this database we identified 22 visceral interventions performed with TRA in 17 morbidly obese patients (age: 53 ± 11 years, female: 71%) with a median BMI of 42.7 kg/m2.

RESULTS

Interventions included radio-embolization (n = 7, 31.8%), chemo-embolization (n = 6, 27.3%), uterine fibroid embolization (n = 4, 18.2%), renal embolization (n = 2, 9.1%), hepatic embolization (n = 1, 4.5%), lumbar artery embolization (n = 1, 4.5%), and renal angioplasty (n = 1, 4.5%). The technical success was 100%. There were no major or minor adverse access site, bleeding, or neurological complications at 30 days.

CONCLUSIONS

This study suggests visceral endovascular interventions performed in morbidly obese patients are safe and feasible.

Exoseal for puncture site closure after antegrade procedures in peripheral arterial disease patients

PURPOSE

Exoseal is a vascular clo-sure device consisting of a plug applier and a bio-absorbent polyglycolic acid plug available in sizes 5 F, 6 F, and 7 F. In this study, we aimed to evaluate the effectiveness and safety of the Exoseal vascular closure device (Cordis Corporation, Bridgewater, New Jersey, USA) for puncture site closure after antegrade endovascular procedures in peripheral arterial occlusive disease (PAOD) patients.

MATERIALS AND METHODS

In this retrospective study, a total of 168 consecutive patients who underwent an interventional procedure due to PAOD, were included. In each case, an antegrade peripheral endovascular procedure was performed via the common femoral artery using the Seldinger technique, and Exoseal 5 F, 6 F, or 7 F was used for access site closure. The primary endpoint was a technically successful application of Exoseal. All complications at the access site within 24 hours were registered as a secondary endpoint.

RESULTS

In a group of 168 patients (64.9% men, average age 71.9±11.9 years), the technical application of Exoseal was successful in 166 patients (98.8%). Within the first 24 hours after the procedure, 12 complications (7.2%) were recorded including, three pseudoaneurysms (1.8%) and nine hematomas (5.4%). None of the complications required surgical intervention.

CONCLUSION

Exoseal is a safe and effective device with high technical success and acceptable complication rates for access site closure after antegrade peripheral endovascular procedures.

Patient skin reactions from interventional fluoroscopy procedures

OBJECTIVE

This article presents relevant physics, technology, and radiobiology along with a summary of operational guidelines for radiation management in interventional fluoroscopy procedures.

CONCLUSION

Fluoroscopically guided interventional procedures offer patients clinical and economic benefits as compared with the alternatives. Radiation-induced skin injuries are uncommon but continue to occur.

ICRP PUBLICATION 120: Radiological protection in cardiology

Cardiac nuclear medicine, cardiac computed tomography (CT), interventional cardiology procedures, and electrophysiology procedures are increasing in number and account for an important share of patient radiation exposure in medicine. Complex percutaneous coronary interventions and cardiac electrophysiology procedures are associated with high radiation doses. These procedures can result in patient skin doses that are high enough to cause radiation injury and an increased risk of cancer. Treatment of congenital heart disease in children is of particular concern. Additionally, staff(1) in cardiac catheterisation laboratories may receive high doses of radiation if radiological protection tools are not used properly. The Commission provided recommendations for radiological protection during fluoroscopically guided interventions in Publication 85, for radiological protection in CT in Publications 87 and 102, and for training in radiological protection in Publication 113 (ICRP, 2000b,c, 2007a, 2009). This report is focused specifically on cardiology, and brings together information relevant to cardiology from the Commission's published documents. There is emphasis on those imaging procedures and interventions specific to cardiology. The material and recommendations in the current document have been updated to reflect the most recent recommendations of the Commission. This report provides guidance to assist the cardiologist with justification procedures and optimisation of protection in cardiac CT studies, cardiac nuclear medicine studies, and fluoroscopically guided cardiac interventions. It includes discussions of the biological effects of radiation, principles of radiological protection, protection of staff during fluoroscopically guided interventions, radiological protection training, and establishment of a quality assurance programme for cardiac imaging and intervention. As tissue injury, principally skin injury, is a risk for fluoroscopically guided interventions, particular attention is devoted to clinical examples of radiation-related skin injuries from cardiac interventions, methods to reduce patient radiation dose, training recommendations, and quality assurance programmes for interventional fluoroscopy.

Evaluation of radiation during EVAR performed on a mobile C-arm

BACKGROUND

The aim of this study was to evaluate radiation exposure during aortic endovascular aneurysm repair (EVAR) on a mobile C-arm using a low dose and pulse mode.

METHODS

We performed a retrospective analysis of a prospectively maintained database on patients undergoing EVAR. Indirect dose measurements of dose area product (DAP, mGy m²) calculated by the C-arm (OEC 9900MD), fluoroscopic time (FT), type of procedure, contrast media volume and body mass index were analysed. To confirm the correlation between direct and indirect DAP measurements, direct dose was measured with radiochromic films on a sample of 15 patients. Film grey level response was calibrated according to a reference dose measurement performed with a calibrated dosimeter. DAP and peak skin dose (PSD, Gy) were measured on each film. Correlation between DAP from direct and indirect measures, and between DAP and PSD, were analysed.

RESULTS

From January 2009 to April 2011, 335 patients underwent EVAR. Complete data were available on 301 procedures including 188 bifurcated, 54 fenestrated, 28 thoracic, 20 branched and 11 aorto-uni-iliac endografts implantation. The respective median FT and DAP was 9.36 min (1.8-67) and 3 mGy m(2) (0.4-28); 27.2 min (2-69) and 7.3 mGy m(2) (1.2-29); 7.75 min (1.2-19.1) and 2 mGy m(2) (0.3-11); 42.98 min (2.4-95.4) and 15.95 mGy m(2) (2.98-77.7); 6.2 min (0.5-36.3) and 2 mGy m(2) (0.3-11). Direct DAP measurement on radiochromic films was strongly correlated with DAP values provided by the C-arm (r = 0.98). PSD correlated weakly with DAP. DAP was significantly increased (p < 0.001) in patients with a body mass index >30. Contrast media volume was significantly increased in the branched endograft group.

CONCLUSION

Indirect DAP values measured by the C-arm are accurate to evaluate radiation exposure. Compared to the literature, our values for standard procedures are significantly decreased by the usage of low dose and pulse mode. DAP for fenestrated and branched procedures was comparable to published DAP values with standard procedures using a regular fluoroscopic mode.

Clinical radiation management for fluoroscopically guided interventional procedures

The primary goal of radiation management in interventional radiology is to minimize the unnecessary use of radiation. Clinical radiation management minimizes radiation risk to the patient without increasing other risks, such as procedural risks. A number of factors are considered when estimating the likelihood and severity of patient radiation effects. These include demographic factors, medical history factors, and procedure factors. Important aspects of the patient's medical history include coexisting diseases and genetic factors, medication use, radiation history, and pregnancy. As appropriate, these are evaluated as part of the preprocedure patient evaluation; radiation risk to the patient is considered along with other procedural risks. Dose optimization is possible through appropriate use of the basic features of interventional fluoroscopic equipment and intelligent use of dose-reducing technology. For all fluoroscopically guided interventional procedures, it is good practice to monitor radiation dose throughout the procedure and record it in the patient's medical record. Patients who have received a clinically significant radiation dose should be followed up after the procedure for possible deterministic effects. The authors recommend including radiation management as part of the departmental quality assurance program.

Interventional procedures: best practice to avoid complications

Technological advances have allowed treatment of patients using interventional radiological imaging including the performance of multiple procedures in almost any vessel, eg, angioplasty, stenting, embolization, and coilings. Patients undergoing any procedure are at risk for complications because of contrast media, radiation exposure, vessel injury, and prolonged time in one position during the procedure. Diagnostic-only procedures minimize use of contrast medium and radiation time, and generally take about one hour to complete. On the other hand, interventional procedures can take several hours and require larger volumes of contrast medium and radiation, as well as increased time lying supine on a procedure table. This article will discuss several potential and known risks associated with interventional procedures, how to monitor for these risks, and evidence-based measures to prevent or minimize their occurrence.

Direct and indirect measurement of patient radiation exposure during endovascular aortic aneurysm repair

With the increasing complexity of endovascular procedures, concern has grown regarding patient radiation exposure. Abdominal aortic aneurysm (AAA) repair represents the most common complex endovascular procedure currently performed by vascular specialists. Our study evaluates the patient radiation dose received during endovascular AAA repair. Over a 3-month period we prospectively monitored the radiation dose in a series of consecutive patients undergoing endovascular AAA repair. All patients underwent standard endovascular AAA repair with one of two commercially available grafts using the GE OEC 9800 unit. Direct measurement of maximum radiation dose at skin level (peak skin dose, PSD) was recorded using GAFCHROMIC radiographic dosimetry film. Indirect measurements of radiation dose (fluoroscopy time and dose-area-product [DAP]) were recorded with the C-arm dosimeter. A total of 12 consecutive patients undergoing standard endovascular AAA repair were evaluated. Mean PSD was 0.75 Gy (range 0.27-1.25). Mean total fluoroscopy time was 20.6 min (range 12.6-34.2) with an average of 92% spent in standard fluoroscopy and 8% spent in cinefluoroscopy. Regarding total fluoroscopy time, 49% was spent in normal field of view and 51% in magnified view. Mean DAP was 15,166 cGy x cm(2) (range 5,207-24,536). PSD correlated with DAP (r = 0.9, p < 0.05) but not total fluoroscopy time (r = 0.18, p > 0.05). PSD also correlated with body mass index (BMI; r = 0.82, p < 0.05). Obese patients had a mean PSD of 1.1 Gy compared to 0.5 Gy in nonobese patients. PSD of all patients was well below the accepted 2.0 Gy threshold for skin injury. PSD correlated with DAP but not total fluoroscopy time. PSD also correlated with BMI, and the mean PSD was significantly increased in obese compared to nonobese patients. Despite the complexity and duration of endovascular AAA repair, the procedure can be performed safely without excessive radiation exposure.

European obesity and the radiology department. What can we do to help?

Obesity is a chronic disease that is now a global epidemic. The numbers of obese people are exponentially rising in Europe, and it is projected that in Europe by 2010 there will be 150 million obese people. The obesity-related health crisis does not only affect adults, with one in four European children now overweight. Radiologists, both adult and paediatric, need to be aware of the magnitude of the problem, and obese patients cannot be denied radiologic evaluation due to their size. Missed diagnosis, appointment cancellation and embarrassing situations for patients when they are referred for a radiological examination for which they are not suitable are all issues that can be avoided if careful provision is made to accommodate the needs of the obese patient requiring radiologic evaluation. This paper will discuss the epidemiology of obesity and the role of radiology in the assessment of obesity and disorders of fat metabolism. The limitations obesity poses to current radiological equipment and how the radiologist can optimise imaging in the obese patient will be described. Dose reference levels and dose control are discussed. Examples of how obesity both hinders and helps the radiologist will be illustrated. Techniques and pre-procedural preparation to help the obese patient in the interventional suite are discussed.

Endovascular treatment of an abdominal aortic pseudoaneurysm as a late complication of inferior vena cava filter placement

Pseudoaneurysms of abdominal aorta after inferior vena cava (IVC) filter placement are uncommon, with associated morbidity and mortality. We report a case in which an abdominal aortic pseudoaneurysm resulted from erosion of a Bird's Nest (Cook, Bloomington, IN) IVC filter into the wall of the abdominal aorta. A 64-year-old woman with an IVC filter placed 10 years prior presented to the emergency department complaining of abdominal pain. A computed tomography scan of the abdomen and pelvis showed a 1.4-cm x 2.0-cm infrarenal aortic pseudoaneurysm adjacent to the IVC filter site. A Zenith endograft (Cook) was used via an open femoral artery exposure to successfully treat the pseudoaneurysm.