Contrast Media Temperature and Patient Comfort in CT of the Abdomen

Study Overview
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Brief Summary
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Abdominal computed tomographic (CT) is an important prognostic tool with regard to the detection of oncological, infectious and other abdominal disorders. The total iodine load (TIL) is regarded as a decisive factor in the opacification of parenchymal structures. The EICAR trial demonstrated that injection with high flow rates of prewarmed contrast media (CM) was safe and patients did not experience any pain, stress of discomfort during injection. Flow rates as high as 8.8 ml/s were injected without any discomfort. All concentrations used (e.g. 240, 300 and 370 mg I/ml) in this study were prewarmed. According to the recent recommendations (ESUR guidelines 10.0) it should be considered to warm iodine-based CM before administration. The hypothesis is that although using CM at room temperature ( 23°C [ 73°F]) might result in lower attenuation of the liver parenchyma than would be achieved using CM pre-warmed to body temperature, diagnostic image quality, patient safety and comfort will not be compromised by not pre-warming CM in this setting. According to the guidelines, it is regarded as best clinical practice to pre-warm CM. Surprisingly, these recommendations are merely based on a hypothetical assumption. In the literature, there are no studies evaluating this topic and it has never been clearly shown to result in a better patient comfort. For this reason, many clinics do not pre-warm their CM in daily clinical routine. Only one study evaluated subjective comfort in hysterosalpingography (HSG), in which CM is injected in to the cavity of the uterus. This study found that prewarmed CM alleviates the pain and decreased the incidence of vasovagal episodes during HSG. To the best of our knowledge, no study showed that prewarmed CM in CT resulted in higher patient comfort, in comparison to CM at room temperature (20° C). Up till now, all CM in the department is prewarmed. In case this study does not show a difference in patient comfort, prewarming the CM can be stopped, resulting in a considerable simplified workflow. The hypothesis is that usage of CM at room temperature (20° C) might result in a decreased level of patient comfort in abdominal CT, in comparison to pre-heated (37° C) CM, with no significant difference in diagnostic attenuation of the liver parenchyma between groups.

Detailed Description
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Abdominal computed tomography (CT) scans are performed daily on a regular basis. Since its advent, rapid technical advances in CT continuously improved image quality. Besides scan technique, the contrast media (CM) injection protocol is the crucial factor in abdominal imaging. Parenchymal contrast enhancement is determined by patient related factors (e.g. cardiac output, blood volume and patient weight), the CM injection protocol and the scan protocol. Much literature has been performed with regard to optimizing CM application and the scan protocol. Flow rate of the CM and patient discomfort have been thoroughly investigated in our department. Heating CM up to body temperature has been daily clinical routine in our department for years. According to the recent recommendations (ESUR guidelines 10.0) it is advised to warm iodine-based CM before administration. Warming the CM is expected to result in a higher patient comfort, based on clinical observation. Kok et al. showed in phantom experiments that high temperature, low iodine concentration and low viscosity significantly decreases injection pressure. Subsequently, as increased temperature reduces the viscosity of the CM, the decreased viscosity is hypothesized to reduce the risk of extravasation. A decreased viscosity might also have a substantial impact on individual tailored CM injection protocols in daily routine scanning as it is speculated that a decrease of viscosity and subsequent decrease in peak injection pressure could influence patient comfort during injection. The EICAR trial showed that prewarmed CM can be safely injected at high flow rates, without patient discomfort, pain or stress. However, the latter was not compared to CM at room temperature. Different CM concentrations are used in different hospitals throughout the world. The higher the concentration, the higher the viscosity of the CM. In present study, only one CM concentrations (e.g. 300 mg/ml) will be used, which is used in daily clinical practice for years. Heating the CM decreases the viscosity. It is therefore expected that the preheated CM in a concentration of 300 mg/ml has a lower viscosity in comparison to the CM at 20° C. Pre-warming CM might be regarded as best clinical practice. No studies have been performed to investigate this statement, nor is there any literature that shows that prewarmed CM has a favorable patient comfort compared to CM injected at room temperature. For these reasons, there remains to be some reluctance and many clinics still not pre-warm their CM. One study, in which CM is injected in to the cavity of the uterus to check for any anatomical variants and causes for infertility, showed a preference for prewarmed CM in hysterosalpingography (HCG). This study found that prewarmed CM alleviates the pain and decreased the incidence of vasovagal episode during the HCG. The hypothesis is that although using CM at room temperature ( 23°C [ 73°F]) might result in lower attenuation of the liver parenchyma than would be achieved using CM pre-warmed to body temperature, diagnostic image quality, patient safety and comfort will not be compromised by not pre-warming CM in this setting. Pre-warming CM requires special equipment and more complex planning and logistics. On the other hand, pre-warming CM may yield higher attenuation levels, comfort and image quality. In case this study does not show a significant difference in patient comfort and diagnostic quality between groups, pre-warming the CM can be stopped, resulting in a considerable simplified workflow.

Official Title
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The Effect of ContrAst Media Temperature on Patient Comfort in Computed tomograpHY of the Abdomen.

Conditions
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Contrast Media, Comfort, Temperature, Abdomen

Intervention / Treatment
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* Other: CM Temperature (20° C)
* Other: CM Temperature (37° C)
* Other: Weight


Participation Criteria
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Eligibility Criteria
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Inclusion criteria Patients referred for abdominal CT Patient ≥ 18 years old and competent to sign informed consent Exclusion criteria Hemodynamic instability Pregnancy Renal insufficiency defined as glomerular filtration rate (GFR) < 30ml/min/1.73m2 (Odin protocol 004720) Iodine allergy (Odin protocol 022199) Age < 18 year Unable to give informed consent or no informed consent obtained Inability to position an 18 gauge cannula in an antecubital vein

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: It is a double-blinded randomised controlled non-inferiority trial conducted according to Guidelines of Good Clinical Practice. The aim of the study is to prospectively compare room temperature CM to pre-warmed CM with regard to image quality, safety, and participant comfort in portal venous abdominal imaging. We are aiming to prospectively enrol 216 consecutive patients, who will be scheduled for contrast enhanced abdominal CT. 216 patients will be divided into 2 different groups: Group I: 300 mg/ml at a temperature of 20° C Group II: 300 mg/ml at a temperature of 37° C Iodine concentrated CM of 300 mg/ml is clinically used as a standard routine injection protocol for all CT scans in our department, including abdominal CT. The scan protocol is identical to our daily clinical practice. The only difference is that 50% of the included patients will receive CM warmed at room temperature. Both CM temperatures are saved/warmed in an incubator.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: CM temperature 20° C<br>CM is administered to the patient at a temperature of 20° C. | Other: CM Temperature (20° C)<br>* CM will be administered at 20° C (room temperature).<br>Other: Weight<br>* The patients' weight is measured prior to scanning by a technician on a weighing scale available in the scanner room.<br>|
| Active Comparator: CM temperature 37° C<br>CM is administered to the patient at a temperature of 37° C. | Other: CM Temperature (37° C)<br>* CM will be administered at 37° C (pre-heated).<br>Other: Weight<br>* The patients' weight is measured prior to scanning by a technician on a weighing scale available in the scanner room.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Liver attenuation | Mean attenuation in Hounsfield Units (HU) is based on three liver segments, preferably segments 2, 5 and 8 (Couinaud classification). Absolute difference in mean attenuation of the liver parenchyma between groups was calculated with a two-sided 95% confidence interval of the difference. | Expected within one month after the CT is performed | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Patient comfort | Patient (dis)comfort during and after injection of CM with varying temperatures, rated on a questionnaire | Immediately after CT | 
| Pain during injection | Assessed with a questionnaire with the option yes/no | Questionnaire immediately after CT | 
| Pain rate | Assessed with a 11-point numeric rating scale (0=no pain; 10=very severe pain) | Questionnaire immediately after CT | 
| Different physiological reactions and sensations injection | Questionnaire has to be filled in which people can tick a box if they had feelings of shivering/goosebumps/or being cold. There is some free space to write down other sensations. | Immediately after the CT | 
| Objective image quality - Signal-to-noise ratio | mean attenuation of the liver divided by the mean standard deviation | Within one month after the CT is performed | 
| Objective image quality - Contrast-to-noise ratio | Mean liver attenuation minus HU of the left paraspinal muscle, divided by the SD of the attenuation of the paraspinal muscle | Within one month after the CT is performed | 
| Subjective image quality | Rated in consensus on a 5-point Likert scale by two readers | Within one month after the end of the study | 
| Body weight | Weight is measured on a weighing scale | Right before the scan is performed | 
| CM volume | The milliliter of CM administered | Information is expected to be collected from the Certegra form available in Impax within 1 month | 
| Flow rate | Flow rate of the contrast media in ml/s | Information is expected to be collected from the Certegra form available in Impax within 1 month | 
| Injection site | Injection site of the CM | Information is expected to be collected from the Certegra form available in Impax within 1 month | 
| Catheter Gauge | Catheter size used for CM injection | Information is expected to be collected from the Certegra form available in Impax within 1 month | 
| Effective milliamperes (mAs) | The effective mAs used in the specific patient | Information is expected to be collected from the Certegra form available in Impax within 1 month | 
| CT Dose Index (CTDI)vol | CTDIvol (in mGy) the patient received | Information is expected to be collected from Impax within 1 month | 
| Dose-length product (DLP) | DLP (in mGycm) the patient received | Information is expected to be collected from Impax within 1 month | 
| Tube voltage | Tube voltage used in the specific scan | Information is expected to be collected from Impax within 1 month |