Radioembolisation in Europe: A Survey Amongst CIRSE Members
Radioembolisation of liver tumours demands many choices from the physician regarding planning of treatment and subsequent follow-up.
An online questionnaire was distributed amongst all members of the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) to investigate the current state of radioembolisation practice.
The survey was completed by 60 centres. The increasing number of radioembolisation procedures may reflect that radioembolisation is increasingly recognised as a valuable treatment option in European cancer guidelines. Imaging modalities play an important role in decision making. Furthermore, there seems to be a trend towards less coil-embolisation of non-target vessels. In addition, type of microsphere, model for dose calculation, complications and future developments are evaluated in this article.
This survey provides insight into the current state of radioembolisation practice across Europe.
KeywordsRadioembolisation Interventional oncology Liver Yttrium
(modified) Body surface area
Cardiovascular Interventional Radiological Society in Europe
Computed tomography angiography
Extrahepatic deposition assessment
Intrahepatic deposition assessment
Lung shunt assessment
Colorectal carcinoma metastases
Medical Internal Radiation Dose
Magnetic resonance angiography
Magnetic resonance imaging
Not applicable/no answer
Positron emission tomography
Radioembolisation induced liver disease
Right gastric artery
Single-photon emission computed tomography
Technetium-99m macroaggregated albumin
University Medical Centre Utrecht
Uniform resource locator
United States of America
Radioembolisation (RE) is a catheter-based internal radiation therapy with high radiation doses aimed at the tumours, while having a minimal effect on the surrounding non-tumorous liver tissue . This treatment relies on the fact that hepatic malignancies derive most of their blood supply from the hepatic artery, while the non-tumorous tissue is mainly supplied via the portal vein . Due to this mechanism, a tumouricidal dose can be obtained while sparing most of the non-tumorous liver tissue [1, 3].
Radioembolisation requires close collaboration of a multidisciplinary team, in which intervention-radiologists and nuclear physicians take the lead together. It is a complex image-guided procedure and can be performed in a large variety of ways. Operators have to make choices ranging from the type of microspheres, type of catheters, use of imaging modalities to methods for calculating the activity. A survey from 2011 (published in 2012) showed that there are many differences in how radioembolisation is performed across 28 centres in Europe . Now, about 7 years later, the radioembolisation community has grown and there have been technical and strategic changes in the field, whereas some centres prefer coiling of (several) arteries, while others do not. There also seems to be a discrepancy between lung shunt correction implementation in the centres and the instructions for use provided by the medical device companies. Furthermore, cone-beam CT (also known as C-arm CT) is introduced as a tool in the radioembolisation procedure and a significant increase in the use of SPECT–CT is seen. To investigate how these changes have impacted daily practice in European centres and what differences exist between centres, a questionnaire was spread amongst all members of the Cardiovascular and Interventional Radiological Society of Europe (CIRSE).
Questions and answers as presented in the survey of 2017
What is the name and location of your treatment centre?
Name and City, Country
In what year did your institution start with radioembolisation?
On estimation, how many radioembolisations were performed at your department in …?
2014: … 2015: … 2016: …
How frequent do you encounter the following indications for hepatic radioembolisation at your department? (average number of patients per year)
Hepatocellular carcinoma/cholangiocarcinoma/colorectal carcinoma metastasis/breast cancer metastasis/neuroendocrine tumour metastasis/other
What kind of microspheres do you use for radioembolisation?
Resin (SIR-Spheres)/glass (TheraSpheres)/other
(a) What imaging modality is most commonly used for pretreatment staging of disease at your institution?
(b) Do you assess the arterial liver anatomy prior to angiography?
No/Yes with MRA/Yes with CTA/other
Are the following conditions contraindications to perform radioembolisation at your institute?
Biliodigestive anastomosis/biliary stenting/biliary drainage/condition after papillotomy/arterio-portal shunt/previous bland or chemo-embolisation/complete portal vein thrombosis/lobar portal vein thrombosis/tumour burden > 70%/primary tumour not resected/extrahepatic disease/ascites drainage
Always a contraindication/most of the time a contraindication/undecided/most of the time not a contraindication/never a contraindication
What kind of imaging do you use to evaluate 99m Tc-MAA distribution?
What is/are the main reason(s) for you to perform evaluation with 99m Tc-MAA before radioembolisation
Lung shunt assessment/extrahepatic deposition assessment (e.g. intestines)/intrahepatic assessment (tumour targeting)/other
When do you consider lung shunting as contraindication?
Shunt volume percentage …/estimated absorbed radiation dose …/other
On average, how many patients (%) do you exclude due to too high lung shunting?
How many of all patients (%) receive dose reduction due to increased lung shunting?
(a) What method do you use to calculate the amount of activity of resin spheres to be injected?
Empirical method/Body Surface Area (BSA) method/partition model/other
(b) What method do you use to calculate the amount of activity of glass spheres to be injected?
Empirical method/MIRD model/other
(a) Which arteries, if any, do you embolise during diagnostic angiography?
Right gastric artery
Never/incidentally/sometimes/most of the time/always
What kind of medication do you prescribe?
(b) During treatment
What kind of microcatheter do you use for the administration of spheres?
Standard microcatheter (e.g. Progreat®, Cantata®, Direxion™)/anti-reflux microcatheter (e.g. Surefire® Infusion System, Balloon Catheter)/other
Do you check whether the position/location of the catheter is the same during the actual treatment as it was during the MAA procedure? If yes, how?
No, I don’t check whether the position is the same/yes, I try to recall the injection position from the 99mTc-MAA injection/yes, I try to closely mimic the injection position from the 99mTc-MAA injection by visually comparing the positions on angiography/yes, but in a different way
What is your preferred sphere administration technique in case of bilobar manifestation of tumour?
Whole liver (bilobar) infusion in a single session via proper hepatic artery/left and right hepatic artery in a single session/sequential left/right radioembolisation with a time gap of… weeks/other
For what purpose do you use C-arm CT (e.g. cone-beam CT) for radioembolisation?
C-arm CT is not used at all/for extrahepatic deposition assessment/to check tumour coverage/for volumetric analysis/calculation of activity needed/other
Do you use post-treatment imaging to evaluate microsphere distribution?
No/yes, 90Y–PET–CT/yes, 90Y–Bremsstrahlung SPECT/yes, 90Y–Bremsstrahlung SPECT–CT/Yes, other
At your institute, what percentage of patients treated with radioembolisation receive a 2nd or 3rd treatment with radioembolisation?
At your institute, what imaging modality for tumour status is most commonly used in radiological follow-up?
On estimation, how frequent (% of all patients) do you encounter the following complications in radioembolisation patients?
Radiation pneumonitis/gastrointestinal complications/pancreatic complications/radioembolisation induced liver disease (RILD)/bile duct complications/cholecystitis/abscess/other
Which of the following (potential) developments could improve radioembolisation treatment in your practice?
Better insight into the distribution of the microspheres in the liver
The possibility to adapt the distribution of the microspheres during the treatment based on real-time imaging feedback on the dose distribution
Improved options to calculate the amount of activity to be injected
Improved catheter designs
Strongly disagree/disagree/neutral/agree/strongly agree
Are there any other (potential) developments you see to improve radioembolisation treatment in your practice?
The welcome page displayed instructions for filling out the survey. Since radioembolisation is a treatment leaning on both interventional radiology and nuclear medicine, respondents were advised to seek help from a colleague interventional radiologist or nuclear medicine physician to answer questions beyond their own expertise.
Respondents could start the survey and finish at a later point in time as it was possible to meanwhile save the results. In order to obtain a complete data set, most questions could not be left blank. Where possible, multiple-choice questions were used for ease and efficiency. Most questions had an option to leave comments, in case the desired option was not listed or additional information was necessary.
Spreading the Questionnaire
All CIRSE members received an invitation by e-mail to fill out the questionnaire on April 13th of 2017. This e-mail contained the uniform resource locator (URL) and password needed to access the questionnaire. A reminder was sent to all CIRSE members 3 weeks after the first invitations were sent to increase the response rate.
Statistics and Analysis
Responses were collected and then analysed in R for Windows (version 3.4.1.). When a question was left blank by a certain centre, the response ‘Unknown’/‘Undecided’/‘No’ (depending on the question) was added and used in the analysis. Descriptive statistics (mean and percentages) were used to display the results. Occasionally, the percentages described do not add up to 100% as there were questions where multiple options could be checked.
Forty percent (40%) of the centres use resin microspheres (SIRSpheres®; SIRTeX, North Sydney, Australia) only, whereas 27% only use glass microspheres (TheraSpheres®; BTG, Ottawa, Ontario, Canada) and approximately 33% use both resin and glass microspheres (Fig. 1B and Table S1). The centres that use both types of microspheres use glass microspheres mainly to treat HCC, while resin microspheres are predominantly used for other tumour types. In addition, several centres mentioned that the choice for a certain type of microsphere was influenced by national reimbursement policies.
SPECT–CT is the main modality to evaluate Technetium-99 m macroaggregated albumin (99mTc-MAA) distribution (77%), besides planar imaging (8%) and SPECT (23%). For most centres, lung shunt assessment is the main reason to perform evaluation with 99mTc-MAA before radioembolisation (98%), followed by extrahepatic deposition assessment (83%), and intrahepatic distribution assessment (65%) (Fig. 4).
The body surface area (BSA) method was the most commonly used method for calculating the amount of activity of resin microspheres to be injected (normal BSA in 75%, modified BSA in 5%) followed by the partition model method (36%) and the empirical method (16%). For glass microspheres, most centres used the Medical Internal Radiation Dose (MIRD) model (59%) or the empirical method (24%) (Figure S4).
The vast majority of centres (91%) tried to closely mimic the injection position from the 99mTc-MAA injection during the actual treatment by visually comparing the position. Five percent of the centres did not check at all whether the position during the actual treatment was the same as during the 99mTc-MAA injection. In case of bilobar manifestation of tumour, 55% of the centres choose a sequential left/right radioembolisation with, in most cases, a time gap of 4–6 weeks (Table S1 and Figure S4). Microsphere administration in the left and right hepatic artery in a single session was preferred by 38% of centres. Only 5% of centres performed whole liver (bilobar) infusion in a single session via the proper hepatic artery. Repeated radioembolisation on the same part of the liver is quite common, with two-thirds of centres performing repeated radioembolisation in at least 2% of patients (Figure S4).
Cone-beam CT is not used at all by 22% of centres. Most of the centres that do use it, use it for multiple reasons: to check tumour coverage (67%), extrahepatic deposition assessment (52%), and volumetric analysis (30%) (Fig. 4).
Seven percent of all centres do not use post-treatment imaging to evaluate microsphere distribution. The other centres often use multiple imaging modalities: Bremsstrahlung SPECT–CT (53%), PET–CT (34%), and Bremsstrahlung SPECT (19%). CT (72%) and MRI (72%) were mostly used for follow-up of tumour status, followed by PET–CT (35%) and PET (2%) (Fig. 4).
The data from this survey give a unique insight into the current state of radioembolisation in Europe. Overall, a tendency towards an increasing number of radioembolisation procedures is seen which may reflect the way radioembolisation is increasingly recognised as a valuable treatment option in European cancer guidelines. There are still considerable differences between European centres with regard to how radioembolisation is performed.
This is the second time a European survey on radioembolisation practices has been performed . The number of responding centres has risen from 28 in the survey from 2011 to 71 in this survey. This rise is probably the result of the fact that all CIRSE members received an invitation to join the survey, aided by the ease of filling out and returning a digital survey as compared to a survey on paper that had to be returned by regular mail. Also, differences in results may be caused by the fact that the current survey was spread to a different group of centres (all CIRSE members) than the previous survey (list of hospitals found on the microsphere-vendors’ websites).
The rate of response to this survey is unclear since the invitation for this survey was sent to all CIRSE members, approximately 7000 people globally. However, this does not give any insight on the amount of centres that these members are currently working at. The number of centres performing radioembolisation in Europe is probably much higher than 63, but there are no exact figures available. Sixty-three is believed to be a fair number given the fact that responders had to invest quite some time to complete the survey without getting a reward in return.
SIR-Spheres remain the type of microspheres used by most centres, although this share seems to have declined. The fraction of centres using TheraSpheres only has risen, as well as the fraction of centres using both products (Figure S2). What looks like an increase and/or decrease in the use of a certain type of microspheres should be interpreted with caution, as the participating centres are different between surveys. The exact number of treatments per centre and the total amount of treatments performed with SIR-Spheres and TheraSpheres are not clearly determined from this survey.
It is generally accepted that cone-beam CT improves the safety and quality of the radioembolisation procedure in several aspects . Therefore, it would be interesting to know whether the centres that do not use cone-beam CT, do not have a cone-beam CT system available or whether they choose not to use it.
Another interesting finding is that although PET–CT is the most accurate modality for performing 90Y-dosimetry, Bremsstrahlung SPECT–CT is still the mainstay for post-treatment 90Y-imaging. This may be due to the higher costs and lower availability of PET–CT systems (Figs. 4 and S3).
There is still some debate amongst centres on whether arterio-portal shunting, ascites drainage and extrahepatic diseases should be considered a contraindication or not. Compared to the survey in 2011 not much change is seen in contraindications, except for a shift towards not seeing complete portal vein thrombosis as a contraindication, which was still undecided in 2011.
In accordance with the trend of more selective injection positions, there seems to be a trend towards less coil-embolisation of non-target vessels. A strong decrease is seen in centres that coil-embolise the RGA (50 vs. 59% in 2011), GDA (34 vs. 71% in 2011) and CA (8 vs. 41% in 2011) (Figure S5). Injections from the proper hepatic artery are rare and selective injection in the right- and left liver arteries with a time gap in between is preferred by most centres. Still, it is surprising that 8% of centres regularly coil the cystic artery since there is no evidence that this is beneficial and may even cause ischaemic cholecystitis [6, 7].
When looking at complications, centres are unambiguous, most of the complications are rare and are reported in only 0–1% of the patients. REILD is encountered more frequently, which explains why several groups have studied the occurrence of this complication and ways to optimise activity calculation to prevent REILD [8, 9].
Although the BSA and empirical model to calculate activity are proven suboptimal, there is still a large number of centres that base their decisions on these models with regard to resin microspheres. The more elaborate partition model is still rarely used as this requires more time and physicians may not be comfortable with the high amounts of activity that can result from adhering to this model. Most centres use the MIRD model for activity calculation with glass microspheres.
This survey shows that a significant fraction of patients is excluded or receives a reduced amount of activity based on lung shunt assessment as assessed with 99mTc-MAA. Withholding treatment or reducing the dose may not be necessary in all of these patients since there is evidence that lung shunting is largely overestimated by 99mTc-MAA [10, 11, 12]. In particular since there are hardly any cases of radiation pneumonitis reported.
Selection bias could be a limitation of the survey, as centres that perform radioembolisation more often might be more inclined to respond to a survey concerning radioembolisation compared to centres that do not provide radioembolisation as a treatment option in their hospital or only perform a limited number of radioembolisation procedures. Furthermore, it remains unclear whether the presented sample is actually representative for the radioembolisation ‘population’ in Europe. It is also possible that the results would look quite different when taking the USA into account.
In general, the results of this survey show a discrepancy between the techniques that are recommended in the literature and the techniques used in daily practice. Examples are the relatively infrequent use of the partition model, scarce use of Y90-PET–CT and cone-beam CT and the high frequency of coil-embolisation. We believe that research initiatives should be aimed at reducing these discrepancies and improving techniques in a way that they can be used by any centre and not only by experts. When asked about future developments, responders indicate that they would benefit from better dosimetry tools to be able to thoroughly evaluate their patients and present them with a more personalised treatment.
In conclusion, this survey provides insight into the current state of radioembolisation practices across Europe. There is still a large variation between centres in the way radioembolisation is performed, and several trends can be recognised when comparing the results to a previous survey.
We would like to thank all participating interventional radiologists and nuclear medicine physicians for spending their precious time to complete the survey. We are very grateful to the Cardiovascular and Intervention Radiological Society of Europe (CIRSE) organisation for facilitating the distribution of this survey, in particular, Daniel Waigl, Maria Emilia Rosenzweig, and Professor Jose Bilbao for their support. Lastly, we thank Annemarie den Harder and Christiaan van Kesteren for their assistance in designing the figures. Christiaan also created the website and helped with spreading the survey.
The first author is funded by a grant from the Dutch Cancer Society (KWF Kankerbestrijding; Grant No. 10307), which was received by Marnix Lam.
Compliance with Ethical Standards
Conflict of interest
The Department of Radiology and Nuclear Medicine of the UMCU receives royalties and research support from Quirem Medical and Terumo. Marnix Lam is a consultant for BTG, Terumo and Quirem Medical. Maarten Smits has served as a speaker for Sirtex Medical and Terumo. All other authors declare to have no conflicts of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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