Trauma CT Scan

If at all possible given the patient’s clinical stability, a trauma CT can be performed before going to OR. Often indications for surgical intervention are already present; however the CT scan can provide additional information to the surgeon, identifying unsuspected and potentially clinically significant injuries. Given the relatively small footprint of most Role 3 facilities the patient can be taken to the OR immediately following the acquisition of the CT scan, with the radiologist providing the pertinent findings to surgeons while in the OR. For clinically unstable patients, this trauma CT can be obtained after continued resuscitation and surgical intervention in the OR.11

CT Protocol (Adult)

Initial acquisition includes non-contrast CT through head and face (to include the entire mandible), at 1 mm axial slice thickness which allows for isotropic sagittal and coronal reformatted images. This scan is followed by a contrast enhanced CT from the level of the circle of Willis through the bottom of the pelvis. Alternatively in the setting of significant lower extremity trauma such as dismounted complex blast injury, the scan can be performed through the lower extremities (default through the feet) allowing evaluation of skeletal and vascular injury of the lower extremities. A discussion with the trauma team should be performed prior to the scan to establish the inferior extent of the scan coverage. Of course, additional information including long bone fractures and metallic fragments can be seen on the scout image, which may alter the scan coverage to include those areas. Some difficulties may arise if the patient is tall and the CT gantry movement does not allow coverage through the lower extremities, however this can be ameliorated by scanning from the head to as low as possible, then either physically sliding the patient up on the gantry or rotating them 180 degrees on the gantry table and scanning through the remainder of the legs.11-13 See Appendix A for more information.

CT Review

3D workstations are a required resource in any civilian trauma center and are a required resource for any Role 3 where major casualties are expected. These workstations allow the radiologist a rapid overview of injuries and ability to zoom into abnormalities. Additionally these powerful workstations allow for rapid creation of detailed 3D shaded surface and multiplanar reconstructions that facilitate a broad overview of numerous soft tissue and osseous injuries at different locations and accentuate the location of fragments. Utilizing these shaded bone or skin surface and Multiplanar Reconstruction (MPR) images can be very helpful for injury tract analysis. The workstation also enables focused arterial vascular analysis, thus supporting early identification of more subtle vascular injuries that can have a significant clinical impact on patient morbidity and mortality.13 In mass casualty situations, a modified workflow may be necessary. The performance of preliminary readings or “wet reads” may be required, especially when there is a sole radiologist present.

IV Access for CT

18g antecubital IV is typically desired – if placed on a medical evacuation platform prior to arrival, the cannula must be thoroughly rechecked/flushed to ensure function and avoid contrast extravasation. More distal upper extremity IVs should typically not be used due to the risk of extravasation and compartment syndrome. A central line can be used for contrast power injection. A large lumen resuscitation catheter such as those utilized for the rapid infusion device (normally rated up to 9cc/sec) can usually handle contrast injection.14 Ensure that the correct size catheter lumen is utilized for the power injection as the catheter will often have various sized lumens. The largest lumen of catheter would be the best to handle the power injection. Of course, should the rapid infusion device be used to infuse fluid/blood products at the same time, it should be turned off during the injection to avoid dilution of the contrast with the instillate. Current intraosseous needles should not be used for contrast administration. Though a few case reports of individual patients undergoing CT examination with contrast injection through IO needles have been published, larger studies in trauma patients are needed to establish efficacy, adverse effects, and bolus timing modifications.

CT Contrast Injection

The goal of the injection is to provide concurrent solid organ enhancement, arterial enhancement, and pulmonary arterial. Typical doses are approximately 150 cc of Isovue 300 or 340 contrasts utilizing a dual phase injection – 80cc at 1.4 cc/sec, followed immediately by 70cc at 3.5 cc/sec for the pan scan. The scan is started 2-3 seconds before the completion of the contrast injection to maximize pulmonary arterial filling. For pediatric injection volume and rates by weight, see Appendix B.

Rectal Contrast

This can be helpful when evaluating penetrating flank injuries or possible rectal involvement below the peritoneal reflection from pelvic injuries. One may utilize 1L of saline/water with the addition of 1 bottle (50ml) of IV contrast. A Foley catheter is used to cannulate the rectum and the balloon is instilled with saline. In the setting of significant rectal or perineal trauma the surgeon may need to place the Foley catheter in the rectum.16

Delayed Images

Routinely performed for further evaluation of identified solid organ injury, identify active extravasation or pseudoaneurysm formation, which can aid surgeons in grading the solid organ injury. Additionally, contrast excretion within the ureters and subsequently into the bladder can also aid in diagnosis of injuries to these structures.

CT Cystogram

50 cc of IV contrast diluted into 500 cc of saline is infused through the indwelling urinary catheter. A minimum of 300 cc and up to 500 cc of this dilute contrast material should be infused to provide adequate evaluation of the integrity of the bladder wall. The catheter is then clamped for the CT examination. This type of exam is performed following the routine trauma CT with 1mm thick images acquired through the pelvis with the bladder filled. If necessary, additional axial imaging of the bladder can be performed following the drainage of the contrast to detect more subtle extraperitoneal bladder injuries which may be obscured by the distended bladder.17

CT Language Settings

Become familiar with the languages available/preloaded on the scanner for breathing instructions, which often include: English, French, Spanish, Japanese, and Chinese. Using interpreters available in your facility, record the same instructions in commonly encountered languages of coalition partners and host-nation patients (e.g., Arabic, Pashtun, Dari, Farsi, Georgian, Italian, Danish, Estonian, etc.). Ensure to select the correct language at the time of scan setup for each patient. Using these instructions will improve image quality for conscious patients.