Foot and Ankle Imaging Review

Anatomy of the Foot

• Base of the Third Metatarsal
  • Central ray (CR) is important for positioning.
  • CR should be located at the base of the third metatarsal, which is significant for exams related to the tarso-metatarsal region.

Lateral Foot Positioning

• Arch orientation
  • Demonstrates the longitudinal arch (front to back), contrasting with the transverse arch (across the foot).
  • Visualization is optimized on the lateral view of the foot.

Anteroposterior Foot Imaging (AP Foot)

• AP vs. AP Axial Examination
  • The presence of open metatarsophalangeal joints indicates that an AP axial view has been used, achieved by angling the CR by 10-15 degrees posteriorly.
  • The angle matches the joint spaces where the CR is directed.
• Joint Visibility
  • Open joint spaces suggest proper angling; misalignment might close them off.

Ankle Imaging

• AP Ankle Positioning

  • Superimposition of the ankle anatomy confirms it as an AP view (toes pointing up).
  • Mortise Joint Visibility: Not present in a standard AP view; requires specific positioning to see properly.

• Oblique Ankle Views

  • AP Oblique (lateral rotation) is to visualize certain structures, with the CR being perpendicular to the image receptor (IR).
  • Mortise View requires internal rotation of 15-20 degrees to show the entire joint properly.
  • The medial malleolus is crucial as CR location.

Calcaneus Views

• Plantodorsal Projection
  • Angle of 40 degrees cephalad; important for elongation of the calcaneus and visibility of the sinus tarsi.
• Lateral Calcaneus
  • CR is located 1 inch inferior to the medial malleolus; positioning and collimation techniques overlap with ankle regions.

Oblique Foot Imaging

• Medial Oblique
  • 30-45 degree angle; visualizes the lateral structures of the foot.
  • CR remains perpendicular; focusing on the base of the fifth metatarsal is essential.

Correcting Lateral Knee Imaging

• Identify missed angles based on the position of the condyles. If they are not superimposed, it indicates a need for a 5-7 degree angle or proper patient rotation.

Shoulder and Humerus Imaging

• AP Scapula vs Scapula Y

  • The position varies; scapula should ideally be parallel to the IR for proper visualization of the glenoid cavity.

• Greater vs Lesser Tubercle

  • Identification of the tubercle helps determine the rotation of the humerus (internal vs external).

Miscellaneous Anatomy

• Navicular and Cuboid Identification
  • Distinguishing between navicular and cuboid based on shape and location within foot anatomy is essential for exams.
• Cuneiforms: Three types recognized: medial, intermediate, and lateral.

Review of Projection Techniques

• Tangential Projection for Patella
  • Also called Sunrise View; skimming over the femur for joint space visualization.

Final Anatomy Review

• Oblique Hand Views
  • Confirming patient positioning (e.g., extended fingers to open joint spaces) is essential for image clarity.

Exam Preparation Strategies

• Understanding core anatomy can simplify decision-making in image evaluations and help eliminate obviously incorrect options during multiple-choice questions.
• Expect 100 questions over a set time period (105 minutes) on the exam, with a focus on practical imaging knowledge (lower extremities most emphasized). Additionally, anticipate questions on chest imaging basics as well.