The CT elbow protocol serves as an examination for the bony assessment of the elbow and is usually performed as a non-contrast study. It can be also combined with a CT arthrogram for the evaluation of chondral and osteochondral injuries.
Note: This article aims to frame a general concept of a CT protocol for the assessment of the elbow. 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 elbow might look like as follows:
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Indications
Typical indications include the following 1-5:
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elbow trauma
proximal radial and ulnar fractures
coronoid process fractures/posteromedial instability
elbow stiffness/osteoarthritis
bone and soft tissue tumors (if MRI is contraindicated)
postoperative follow up, implants and their complications
interventions (e.g. CT-guided biopsy)
Purpose
The purpose of an elbow 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 setting of elbow stiffness, CT can demonstrate osteoarthritis, bony spurs, joint incongruency, loose bodies and ankylosis 3.
In the setting of inflammatory or neoplastic processes, the purpose of an elbow CT 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.
Technique
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patient position
supine position
the arm in question is raised above the head
the affected elbow should be close to the center of the scanning table
if possible elbow extended palm facing upwards
upper body and head bent to the contralateral side
contralateral arm next to the body
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tube voltage
≤120 kVp
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tube current
as suggested by the automated current adjustment mode (≤150 mAs)
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scout
mid-upper arm to mid-forearm
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scan extent
including the humeral metaphysis and the proximal third of the ulna and radius
might vary depending on the indication
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scan direction
caudocranial
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scan geometry
field of view (FOV): ≤150 mm (should be adjusted to increase in-plane resolution)
slice thickness: ≤0.625 mm, interval: ≤0.3 mm
reconstruction algorithm: bone, soft tissue
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contrast injection considerations
non-contrast (e.g. fractures)
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single acquisition with monophasic injection (venous)
contrast volume: 70-100ml with 30-40 mL saline chaser at 3-5 mL/s
scan delay: 45-60 seconds
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multiplanar reconstructions
sagittal images: perpendicular to the interepicondylar line aligned through the humerus and proximal ulna
coronal images: parallel to the interepicondylar line and the humeral shaft
axial images: parallel to the joint line from the capitulum and trochlea perpendicular to the humerus
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additional multiplanar reformations on a bent elbow
axial images: perpendicular to the forearm
coronal images: parallel to the ulna and radius
Practical points
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
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dose optimization 1
use iterative reconstruction algorithms if available
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imaging of implants 1
use monochromatic reconstructions in dual-energy CT scans
use additional wide window setting
might require a higher tube voltage