The CT hand and wrist protocol serves as an examination for the bony assessment of the wrist and is often performed as a non-contrast study and less often as a contrast-enhanced study. A CT wrist can be also conducted as a CT arthrogram for the evaluation of ligamentous injuries and the triangular fibrocartilage complex.
Note: This article aims to frame a general concept of a CT protocol for the assessment of the wrist and hand. 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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Images:
Indications
Typical indications include the following 1-8:
complex distal radial fractures and ulnar fractures
inflammatory or infectious processes
bone and soft tissue tumors (if MRI is contraindicated)
postoperative follow up, implants and their complications
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ligamentous injury
Purpose
The aim of a wrist CT in the setting of traumatic injuries or fractures is their timely diagnosis as well as their classification and characterization 1.
In the setting of inflammatory or neoplastic processes, the purpose of a CT hand or wrist 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 2. If gout is suspected a dual-energy CT can visualize urate crystal deposits 2.
In the setting of carpal instability, a non-contrast CT can demonstrate bony morphology and osteoarthrosis of the radiocarpal and midcarpal joint in the late stages of the disease 3.
A CT arthrogram of the wrist is done to demonstrate and localize scapholunate or lunotriquetral ligament tears as well as to detect and classify triangular fibrocartilage complex injuries 4-8.
Technique
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patient position
prone position
the hand in question is raised above the head in the center of the scanning table
the elbow should be extended palm facing downwards
the head can rest on the other arm
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tube voltage
≤120 kVp (100 kVp)
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tube current
as suggested by the automated current adjustment mode
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scout
whole hand to the distal third of the forearm
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scan extent
wrist: including radial metaphysis and proximal third of the metacarpal bones
hand: includes the entire hand to the radial metaphysis
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scan direction
craniocaudal
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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
contrast volume (for iodine concentration of 300 mg/mL): 70-100ml (0.1 mL/kg) with 30-40 mL saline chaser at 3-5 mL/s
scan delay: 40-60 seconds (venous) or 20-25 seconds (angiogram)
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multiplanar reconstructions
axial images: perpendicular to the forearm-3rd metacarpal axis and fairly parallel to the radiocarpal joint, dorsum of the wrist oriented upwards
coronal images: parallel to the forearm and the metacarpal bones forearm pointing downwards
sagittal images: in the axis of the forearm and the 3rd metacarpal bone, perpendicular to the coronal images and the radiocarpal joint, forearm pointing downwards
slice thickness: bone ≤1,5 mm, soft tissue ≤3 mm, overlap 50%
Practical points
patient positioning before 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 or artificial intelligence-based 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
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