{"id":88648,"date":"2026-05-06T13:20:35","date_gmt":"2026-05-06T13:20:35","guid":{"rendered":"https:\/\/www.imv-imaging.com\/?p=88648"},"modified":"2026-05-06T13:22:29","modified_gmt":"2026-05-06T13:22:29","slug":"news-to-pump-inject-or-not-to-pump-inject-that-is-the-question","status":"publish","type":"post","link":"https:\/\/www.imv-imaging.com\/en\/2026\/05\/news-to-pump-inject-or-not-to-pump-inject-that-is-the-question\/","title":{"rendered":"To Pump Inject or not to Pump Inject? That is the question"},"content":{"rendered":"\n

<\/path><\/svg><\/span><\/span>Estimated reading time: <\/span>8<\/span> minutes<\/span><\/p>\n\n\n\n

When reviewing the images of a CT scan, we can readily identify structures and organs within the body, since they are represented by varying shades of grey, but it is more difficult to discern fine details like the vascular anatomy and precise boundaries between certain organs. These difficulties, in turn, can sometimes pose challenges when trying to make an accurate diagnosis.  <\/p>\n\n\n\n

The administration of contrast media during a scan allows for better visualisation of finer structures and delineation of organs.  <\/p>\n\n\n\n

How?<\/strong> <\/p>\n\n\n\n

Contrast agent contains iodine, which has a high atomic number. Elements with a high atomic number absorb high energy X-rays, so that the X-rays which encounter the iodinated contrast are strongly attenuated in comparison to those which pass through adjacent tissues. The scanner can then generate images with greater tissue contrast, emphasizing specific areas or anatomical features. <\/p>\n\n\n\n

Why?<\/strong> <\/p>\n\n\n\n

Enhanced contrast facilitates the clear delineation of various organs, including the liver, pancreas, kidneys, and spleen. Each organ is perfused by contrast media at different times and in different ways. <\/p>\n\n\n\n

Similarly, the blood vessels fill with contrast and appear as a bright white tract that is visible throughout the scan. Contrast can highlight any abnormalities in the blood supply, which could identify tumors, inflammation or infection, and\/or traumatic injury. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n
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A pre contrast <\/strong>transverse plain image of the liver. The blood vessels and gall bladder are poorly delineated due to the low contrast between these tissues.<\/p>\n<\/div>\n\n\n\n

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In this post contrast <\/strong>image of the same patient, the addition of contrast highlights the blood vessels and aids in delineating the gall bladder from the adjacent hepatic parenchyma.<\/p>\n<\/div>\n<\/div>\n\n\n\n

Where?<\/strong> <\/p>\n\n\n\n

\"contrast<\/figure>\n\n\n\n

Contrast media is delivered via peripheral intravenous (IV) access and following administration; the contrast follows the expected circulatory pathway: <\/p>\n\n\n\n

The quality of the visible contrast in the vessels is determined by the amount administered, the pressure and speed at which it is injected, and the time over which the scan is performed. <\/p>\n\n\n\n

After extensive studies on contrast agent volumes, researchers determined that administering 2ml per kilogram\u2014 up to a maximum of 100ml \u2014of a standard contrast agent containing 300mg iodine per ml offers strong diagnostic enhancement while minimizing the risks of allergic reactions and kidney strain (Kan et al, 2022)<\/a>. <\/p>\n\n\n\n

IV contrast should be warmed to body temperature to reduce viscosity and can be administered in one of two ways: hand injection or pump injection. <\/p>\n\n\n\n

Hand Injection<\/strong> <\/p>\n\n\n\n

A syringe with the appropriate volume of contrast, is connected to a preferably wide gauge peripheral access IV catheter and injected as quickly as possible. The procedure is completed in the scan room and, following the injection, the staff member quickly exits the room before the scan starts. <\/p>\n\n\n\n

The flow rate and pressure of a hand injection is unpredictable, leading to discrepancies in the quality of contrast in the circulatory system. The reasons for this can include the size of catheter, the type of syringe, the person injecting the contrast, and the time delay before starting the scan. <\/p>\n\n\n\n

\"octopus<\/figure>\n\n\n\n

Attachment of the syringe can also cause patient movement if the peripheral IV catheter is difficult to access, meaning the post-contrast images will not be comparable to the pre-contrast set. The use of a single or double lumen octopus extension set can be used, but enough saline must be pushed through the line after contrast administration to ensure the full volume of contrast is delivered and no residual contrast remains.  <\/p>\n\n\n\n

If contrast is not warmed, and then maintained at body temperature before injection, then injecting the contrast is more difficult as viscosity is increased.  <\/p>\n\n\n\n

Pump Injection<\/strong> <\/p>\n\n\n\n

A pump injector (also referred to as a power injector or a pressure injector) works with a pre-filled or manually-filled syringe, which is connected to the peripheral IV catheter via an extension set, prior to the non-contrast scan. The extension set reduces the risk of patient movement affecting image quality. The flow rate, pressure and amount of contrast injected is programmed into the injector interface, and this step can be completed without a staff member present in the scan room.  <\/p>\n\n\n\n

Most modern injectors are dual chambered, enabling a saline \u201cchaser,\u201d or bolus, to be administered following contrast. The chaser\u2019s key role is to push the contrast through the circulation to improve image quality, vascular enhancement and reduce streak artefact. It also ensures that there is no contrast left in the peripheral IV catheter which could be inadvertently flushed into the patient if the catheter were to be subsequently used for other purposes (administration of fluids\/medication). This would lead to a secondary demand on the kidneys.  <\/p>\n\n\n\n

\"power<\/figure>\n\n\n\n

Since the volume, flow rate and pressure are all pre-programmed, the image quality is significantly improved and more consistent. In conjunction with bolus tracking (where the scanner takes a series of slices in the same place to detect contrast) certain scans can be initiated at optimum filling for the area of interest. <\/p>\n\n\n\n

Injection Timings<\/strong> <\/p>\n\n\n\n

Each area, organ or lesion will fill with contrast at a particular time after the start of the injection. Timings for the most common regions of interest are as follows: <\/p>\n\n\n\n

Area of Interest<\/strong> <\/td>Scan Delay<\/strong> <\/td><\/tr>
Thorax <\/td>15-25 seconds <\/td><\/tr>
Abdomen and Pelvis <\/td>60-70 seconds <\/td><\/tr>
Brain <\/td>60 seconds <\/td><\/tr>
Spine <\/td>60 seconds <\/td><\/tr>
Soft Tissues <\/td>60 seconds <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Less commonly performed scans include: <\/p>\n\n\n\n

Area of Interest<\/strong> <\/td>Scan Delay<\/strong> <\/td><\/tr>
Intravenous Urogram (IVU) <\/td>60 seconds <\/td><\/tr>
Liver Shunt\/Insulinoma <\/td>7-15 seconds (depending on patient size) <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Pressure and Rate of Injection<\/strong> <\/p>\n\n\n\n

The higher the rate of flow, the larger the bolus of contrast in the vessel, meaning better attenuation and contrast visibility. <\/p>\n\n\n\n

Ultimately, the size of catheter used for access will determine the pressure (PSI) and maximum rate (ml\/s) at which the injection can be given. This is due to the length and diameter of the catheter and the peak pressure it can withstand before the risk of rupture. <\/p>\n\n\n\n

It is also important to consider patient size and weight, and the volume of contrast to be injected, when choosing an appropriate catheter. <\/p>\n\n\n\n

A maximum of 325 psi should be used, and flow rate should be set depending on the catheter size: <\/p>\n\n\n\n

Guage<\/strong> <\/td>ml\/s<\/strong> <\/td><\/tr>
22 <\/td>2-3 <\/td><\/tr>
20 <\/td><5 <\/td><\/tr>
18 <\/td><7 <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The rate at which an injection is administered is important because delivering differing volumes of contrast over the same period may result in image quality issues. <\/p>\n\n\n\n

For instance, an injection of 6ml contrast at 3ml\/s will result in an injection time of 2 seconds.  <\/p>\n\n\n\n

Injecting the full volume at such a high rate may result in a high concentration of contrast entering the central veins and causing streak artefact, leading to poor image quality as other structures may be obscured. Another consideration is that the peak enhancement may occur too early, resulting in poor enhancement of the area of interest.  <\/p>\n\n\n\n

Although image quality is a major consideration in contrast injections, potential tissue damage due to extravasation is also a risk if administration rates are significantly high.  <\/p>\n\n\n\n

To circumvent these issues, ensure that the rate of contrast injection leads to a contrast administration period of approximately 20 seconds. The required rate can be calculated by dividing the total amount of contrast to be administered by 20. <\/p>\n\n\n\n

Using this rule, the rate of injection required to administer 6ml of contrast over 20 seconds is 0.3ml\/s.  <\/p>\n\n\n\n

So, to Pump Inject or not to Pump Inject?<\/strong> <\/p>\n\n\n\n

Hand injections are unpredictable <\/p>\n\n\n\n