Upper Extremity Radiography and MRI Study Guide

Flashcards covering key terms and definitions for shoulder, hand, and wrist imaging including X-ray, CT, and MRI modalities.

Routine shoulder series

Consists of AP external rotation and AP internal rotation radiographs.

AP external rotation (shoulder structural view)

Best for profiling the greater tuberosity and evaluating the AC joint, glenohumeral joint space, proximal humerus, lateral clavicle, and upper/lateral scapula.

Glenohumeral joint space (normal measurement)

Approximately $5\,mm$ on an AP external rotation radiograph.

AP internal rotation (shoulder structural view)

Shows the humeral head rotated about $90$ degrees compared with AP external rotation; best for profiling the lesser tuberosity.

Oblique sagittal MRI plane (shoulder)

The imaging plane oriented parallel to the glenoid fossa.

Oblique coronal MRI plane (shoulder)

The imaging plane oriented parallel to the supraspinatus muscle.

MR arthrography

Uses intra-articular contrast to distend the joint; helpful for identifying labral tears, capsular pathology, and subtle soft tissue tears.

PA hand view (setup)

Positioned palm down with the beam entering posterior-to-anterior and the central ray through the $3rd$ MCP joint.

Normal hand alignment (lateral view)

The long axes of the $3rd$ metacarpal, capitate, lunate, and radius should align within about $10$ degrees.

Metacarpal sign

A line tangential to the heads of the $4th$ and $5th$ metacarpals; it normally should not cut through the $3rd$ metacarpal head.

Positive metacarpal sign (pathology)

Suggests shortening of the $4th/5th$ metacarpals and is classically associated with Turner syndrome and pseudohypoparathyroidism.

Sesamoid bones (hand)

Most consistently located at the palmar/volar aspect of the $1st$ MCP joint of the thumb.

VISI (Volar Intercalated Segment Instability)

Suggested by palmar/volar lunate rotation greater than $15$ degrees.

DISI (Dorsal Intercalated Segment Instability)

Suggested by dorsal lunate extension greater than $10$ degrees.

Radial inclination

The normal slant of the radius on a PA wrist view, measuring about $15-25$ degrees.

Oblique wrist view

Best for visualizing the trapezium and its articulations, radial and ulnar styloids, and certain carpal fractures.

Wrist CT (primary value)

Most valuable for depiction of bone, including detailed assessment of fractures, displacement, and complex osseous anatomy.

Axial CT (wrist)

Cross-sectional view useful for identifying structures compressing the median nerve in the carpal tunnel or ulnar nerve in Guyon’s canal.

ABCS interpretation method

A systematic approach to radiology where A = alignment/anatomy; B = bone density/signal; C = cartilage and joint spaces; S = soft tissues.

T1-weighted MRI

MRI sequences primarily used to define anatomy.

T2-weighted/STIR/fat-suppressed MRI

Sequences used to detect abnormal fluid, edema, inflammation, and injury signal.

ABCD interpretation method (MRI)

A systematic approach where A = alignment; B = bone signal; C = cartilage/TFCC structures; D = edema.

TFCC (Triangular Fibrocartilage Complex)

Structure including ligaments and an articular disc that stabilizes the distal radioulnar/ulnocarpal region and cushions load on the ulnar side.

Edema (MRI appearance)

Represents abnormal fluid and appears as high signal (bright) on T2 or STIR images; referred to as the "footprint of injury."