Carpal Canal - Marshall Method

Superoinferior Projection – Carpal Canal

Marshal Method

Patient Position:

• If the patient cannot assume or maintain the carpal canal gaynor hart method, a same image may be obtained.
• Have the patient dorsiflex the wrist as much as is tolerated and lean forward to place the carpal canal tangent to the image receptor. The canal is easily palpable on the palmar aspect of the wrist as the concavity between the trapezium laterally and hook of hamate and pisiform medially.

Part Position – Marshall Method

When dorsiflexion of the wrist is limited. Marshall suggested placing a 45 degree angle sponge under the palmar surface of the hand. This slightly elevates the wrist to place the carpal canal tangent to the central ray. A slight degree of magnification exists because of the increased object to image receptor distance.

Central Ray

• Tangential to the carpal canal at the level of the midpoint of the wrist.
• Angled toward the hand approximately 20 to 35 degrees from the long axis of the forearm.

Evaluation Criteria:

• With either approach, the following should be clearly demonstrated.
• Carpals in an arch arrangement
• Pisiform in profile and free of superimposition
• Hamulus of hamate
• All carpals