CT pelvis (protocol)
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The CT pelvis protocol serves as an outline for the acquisition of a pelvic CT. As a separate examination, it might be performed as a non-contrast or contrast study or might be combined with a CT hip or rarely with a CT cystogram. A pelvic CT might be also conducted as a part of other scans such as CT abdomen-pelvis, CT CAP, polytrauma CT or CT angiograms of the aorta or lower extremities, but those protocols are beyond the scope of this article and discussed separately.
Note: This article aims to frame a general concept of a CT protocol for the assessment of the pelvis. Protocol specifics will vary depending on CT scanner type, specific hardware and software, radiologist and perhaps referrer preference, patient factors e.g. implants, specific indications.
Contrast doses apply for CT examinations in adults.
A typical CT of the pelvis might look like as follows:
Typical indications include the following 1-10:
inflammatory or infectious processes
implants and their complications (e.g. intrapelvic cup migration)
pelvic interventions (e.g. CT-guided injections, biopsy, drainage)
suspected bladder rupture or bladder leak
The purpose of a pelvic CT in the setting of a traumatic injury or suspected fracture is their timely diagnosis as well as their classification and characterization 1,2.
In the case of hemorrhage or suspected vascular injuries, the primary goal of the CT is the detection of the bleeding vessel 3.
In the setting of inflammatory or neoplastic processes, the purpose of a CT pelvis is the localization and characterization of the respective process, its extent and its relation to the adjacent tissues as well as the detection of potential complications 5-8.
The purpose of a CT during an intervention is image guidance and in this setting, the scan extent will be reduced to the respective segment 9,10.
both arms elevated
as suggested by the automated current adjustment mode
mid-abdomen to below the lesser trochanter
including iliac crest and lesser trochanter
might vary depending on the indication
field of view (FOV): 300 mm (should be adjusted to increase in-plane resolution)
slice thickness: ≤0.625 mm, interval: ≤0.5 mm
reconstruction algorithm: bone, soft tissue
contrast injection considerations
non-contrast (e.g. fractures, foreign body)
contrast volume: 70-100 mL
biphasic acquisition with monophasic injection (arterial ± venous)
contrast volume: 80-100ml with 30-40 mL saline chaser at 4-5 mL/s
bolus tracking: aorta abdominal
arterial acquisition: minimal scan delay
venous acquisition: ~40 seconds after an arterial phase or 65-80 seconds after contrast injection
single acquisition with monophasic injection (venous)
contrast volume: 70-100ml (0.1 mL/kg) with 30-40 mL saline chaser at 2-3 mL/s
scan delay: 65-80 seconds or 40-50 seconds after bolus tracking
single acquisition with a biphasic injection or split bolus
50-75 ml contrast media at 2-3 mL/s
50 ml contrast media and 30-50 ml saline chaser at 4 mL/s starting at ~ 45 seconds
scan delay: 70 seconds
single breath-hold: inspiration
axial images: strictly axial to the pelvic axis
coronal images: strictly coronal to the pelvic axis
sagittal images: sagittal aligned through the center of the sacral bone and the pubic symphysis
slice thickness: bone ≤2 mm, soft tissue ≤3 mm, overlap 50%
patient positioning prior to scanning might reduce and facilitate multiplanar reconstructions
reconstructions in both standard kernel and high-resolution kernels
depending on the exact indication the scan might require an extension of the scan field
use iterative reconstruction algorithms if available
adjust expected CTDIvol and noise to patient size
imaging of implants 1