Use of IV contrast media in radiotherapy planning CT scans: A UK audit

doi:10.1016/j.radi.2016.06.006

Radiography

Volume 22, Supplement 1, December 2016, Pages S28-S32

https://doi.org/10.1016/j.radi.2016.06.006 Get rights and content

Highlights

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Only 6% (n = 3) centres administer to all 8 tumour sites recommended by RCR (2004).
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Over 70% centres deliver IV contrast to at least one additional tumour site not recommended by RCR (2004).
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15% (n = 8) of centres do not have extravasation policies.
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17% (n = 9) of centres report eGFR formula used as unknown.

Abstract

Aim

This article reports on a UK survey of radiotherapy centres. The primary aim was to define the extent and range of practice for which intravenous (IV) contrast is used within radiotherapy planning (RTP) Computerised Tomography (CT) scans, including how well centres adhere to RCR guidelines (2004, 2010). The secondary aim was to identify whether current guidelines are adequate or should be redefined to reflect new evidence based practice.

Materials and method

A UK wide survey was undertaken, questionnaires were sent electronically via survey monkey to all 80 UK cancer centres obtained from the Society and College of Radiographers (SCoR) website. Questionnaires included closed, open and Likert Scale questions to allow complete analysis of protocols and opinions relating to IV contrast use and implementation. Data was collected within a four-week period during October 2014.

Results

Eighty three percent of centres responded, 98% of responding centres now routinely deliver IV contrast. However, only 6% of centres deliver IV contrast to all 8 of the RCR 2004 recommended tumour sites. RCR 2010 compliance was also poor with the most common response to method of eGFR calculation stated as unknown. Fifteen percent of centres also did not have extravasation policies.

Conclusion

The results suggest that it is perhaps time to reconsider a revision to the existing guidelines based on new evidence regarding good practice. There are many areas such as flow rates, timings, dosimetric corrections and advanced techniques which require further research to enable standardised guidelines to be identified.

Introduction

One of the inherent issues of computerised tomography (CT) versus magnetic resonance imaging (MRI) is the lack of soft tissue definition available in CT imaging.¹ Use of intravenous (IV) contrast injected directly into the patient's vein immediately prior to the radiotherapy planning (RTP) CT scan allows enhanced visualisation of target volumes and adjacent organs at risk; making delineation of radiotherapy target volumes and organs at risk easier and more accurate.¹

The extent of administration of intravenous (IV) contrast media within RTP CT is largely undefined. The Royal College of Radiologists (RCR) (2004)² report advised IV contrast for specific tumour sites (Table 1).

In 2010, and updated in 2015,¹ further national guidelines were released identifying standards of administration.³ The key points from these guidelines included:

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Risk factors should be assessed for all patients prior to IV contrast administration.
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eGFR should be assessed for all non-emergency patients, a minimum eGFR of >60 ml/min/1.73 m² is recommended.
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Metformin should not be stopped unless eGFR is <60 ml/min/1.73 m² and in consultation with the referring clinic.
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Cannulas should be left in situ for at least 30 min post injection for all high risk patients.
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All centres should have treatment guidelines for reactions including extravasation.

The benefits of using IV contrast are well acknowledged1, 2, 4 with many radiotherapy clinical trials requiring its use to aid target volume delineation and enable tumour visualisation.

Currently no standardised UK guidelines exist with respect to IV contrast protocols specific to radiotherapy planning where requirements in enhancement are often different to diagnostic studies. Many small single centre studies have investigated single aspects of contrast delivery and protocols. However, none of the studies look at the full range of IV contrast administration practice. Anecdotal evidence suggests departmental protocols may be derived from diagnostic CT protocols; these may be outdated or inappropriate for current RTP requirements. Given the pace at which planning techniques have developed and now rely on enhanced visualisation for delineating planning target volumes and identification of organs at risk, it is pertinent to conduct a full assessment of practice to ensure optimal protocols are utilised. This audit aimed to assess which protocols are followed by individual radiotherapy departments and also consider whether RCR guidelines (2004, 2010)2, 3 are sufficient for current practice or reflective of current research and knowledge.

Section snippets

Design

A comprehensive electronic questionnaire was sent to all 80 UK cancer centres, both qualitative and quantitative questions were used to promote objectivity and reduce researcher bias. The content and design of the questionnaire was based upon previous national studies of IV contrast administration.4, 5 Prior to distribution a pilot study of 5 randomly selected centres was performed to ensure the responses could be analysed in relation to the study questions and verify that the phrasing of the

Results

In total 83% of centres responded (n = 66/80), no response was received from 17% (n = 14/80) of centres. There were 10% (n = 8) partial responses which were excluded prior to data analysis due to a high level of unit non-responses. However, it is not known if these centres were true non-responses or if they re-started the questionnaire under a new submission as demographic data was not collected until the end of the survey. Of the 66 responding centres 5% (n = 3/66) were not operational, 5% (n

RCR 2004 compliance

The use of IV contrast within RTP CT scans has significantly increased with 98% (n = 51) of centres now routinely administering to at least 1 site; compared to 57% (n = 33)⁵ and 76% (n = 38)⁴ in previous studies. RCR (2004)² recommended tumour sites has also increased with 6% (n = 3) of centres now administering to all 8 sites, compared to zero centres as identified in previous studies.4, 5 Full compliance is still relatively poor with over 40% of centres administering to only 5 sites or less,

Limitations

The main limitation of this study is lack of knowledge of the actual level of IV contrast enhancement achieved using current protocols at individual centres. For the current study centres were only asked how sufficient they feel the enhancement achieved using current protocols is, using a Likert scale response. This is a subjective question and doesn't qualify actual benefit; as generally centres have no other data for comparison. Due to this limitation a full further research study is needed

Conclusion

It is clear from the findings that new guidance specific to radiotherapy planning is required covering a wider area of IV practice to ensure optimal protocols are adopted that reflect the current evidence base. This is supported with two thirds of centres agreeing or strongly agreeing when asked if updated guidelines would be useful. Recommendations include:

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Recommended tumour sites should be redefined to reflect current evidence based practice, including tumour sites identified from clinical

Conflict of interest statement

None.

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Citation Excerpt :
All of the Irish departments surveyed used IVC in clinical practice, which is similar to the UK use (98%) reported in 2014 [14]. No Irish department administered IVC to all nine of the RCR recommended tumour sites, while 6% of UK departments are fully compliant with these recommendations [14]. However, these results may not reflect poor compliance within Irish departments as small departments may refer less common disease sites (e.g. cholangiocarcinoma) to larger referral centres, thus not routinely imaging the range of RCR recommended sites.
While Computerised Tomography (CT) remains the gold standard in radiation therapy (RT) planning, inferior soft tissue definition remains a challenge. Intravenous contrast (IVC) use during CT planning can enhance soft tissue contrast optimising Target Volume (TV) and Organ at Risk visualisation and delineation. Despite this known benefit, there are no guidelines for when and how to use IVC in RT planning scans in Ireland.
The study aims to examine the patterns of practice in relation to the use of IVC in RT planning scans in Ireland and to determine the level of compliance with international guidelines. Radiation Therapists (RTT) IVC training will also be investigated.
An anonymised online survey was designed based on previously-reported literature. This was distributed to all RT departments in Ireland. The survey contained open, closed and Likert scale questions that investigated IVC practices in each department.
75% (n = 9/12) of Irish departments responded. All responding departments reported using IVC. RTTs cannulated patients in 67% (n = 6/9) of the departments and administration contrast in all departments. Variations from recommended guidelines were found in disease sites where IVC was routinely used and in the assessment of renal functioning prior to contrast administration. IVC training varied in duration and number of supervised procedures required to fulfill competencies.
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Use of IV contrast media in radiotherapy planning CT scans: A UK audit

Highlights

Abstract

Aim

Materials and method

Results

Conclusion

Introduction

Section snippets

Design

Results

RCR 2004 compliance

Limitations

Conclusion

Conflict of interest statement

Clin Oncol (R Coll Radiol)

Ann Oncol

Clin Oncol (R Coll Radiol)

Acad Radiol

Radiother Oncol

Radiother Oncol

Radiother Oncol