Contrast Media Temperature and Patient Comfort in CT of the Abdomen
Contrast Media Temperature and Patient Comfort in CT of the Abdomen
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.
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.
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