S2_L2: Anatomy, X-ray, CT Scan, & MRI of the Shoulder Flashcards
Basic CT Protocol
- Taken parallel to the bony glenoid fossa
- Taken parallel to the supraspinatus tendon (SST)
- For severe or comminuted fractures
A. Axial view
B. Oblique sagittal view
C. Oblique coronal view
D. 3D view
- B
- C
- D
Basic CT Protocol
- Reformatted from axial cuts for assessment of complex fractures
- Taken perpendicular to the humeral shaft
A. Axial view
B. Oblique sagittal view
C. Oblique coronal view
D. 3D view
- D
- A
Routine Radiologic Evaluation: Basic Projections
- AP External or Internal Rotation View
- Upright AP view with and without weight
- AP or Lateral view
A. For the acromioclavicular joint
B. For the shoulder
C. For the scapula
- B
- A
- C
Enumerate the four shoulder complex structures seen on the x-ray of a newborn
- Clavicle
- Scapular body
- Humeral shaft
- Proximal humeral head
NOTE: All the structures found in an adult radiograph are not readily seen in a neonatal radiograph. But by ~8 y/o, more of the structures may be viewed.
Routine Radiologic Evaluation: AP External Rotation
Modified TF
A. For this view, the image is taken in the true AP anatomic position of the shoulder in ER in the supine position.
B. The central ray is directed perpendicular to a point 1 inch inferior to the coracoid process and the receptor / receiving plate.
TT
Routine Radiologic Evaluation: AP Internal Rotation
Modified TF
A. For this view, the image is taken with the arm and shoulder in IR.
B. The central ray is directed perpendicular to a point 1 inch inferior to the coracoid process.
TT
Routine Radiologic Evaluation: AP (B) with & without weights / stress
Modified TF
A. This view demonstrates the bilateral AC joints for comparison.
B. The central ray is directed perpendicularly to the midline of the body at the level of the acromioclavicular joints.
TT
Routine Radiologic Evaluation: AP (B) with & without weights / stress
Modified TF
A. Stress views (with weights) use 20-25 lbs weight to drag the UE down.
B. In AC joint stability, this view will cause separation of the AC joints.
FT
A: Stress views (with weights) use 10-15 lbs weight to drag the UE down.
Routine Radiologic Evaluation: AP View
Modified TF
A. The AP view demonstrates the entire scapula, the medial half of scapula is seen free of superimposition of ribs and lungs; however, the lateral half is superimposed.
B. The central ray is directed perpendicular to the midscapular area at a point 1 inch inferior to the coracoid process.
FF
A: The AP view demonstrates the entire scapula, the lateral half of scapula is seen free of superimposition of ribs and lungs; however, the medial half is superimposed.
B: The central ray is directed perpendicular to the midscapular area at a point 2 inches inferior to the coracoid process.
Routine Radiologic Evaluation: Lateral View
Modified TF
A. This view is best for evaluating the body of the scapula as the scapula is projected clear of the rib cage.
B. The central ray is directed perpendicular to the mid-lateral border of the scapula.
TT
Routine Radiologic Evaluation: Axillary View of GH joint
Modified TF
A. This view is the anteroposterior axial projection of the GH joint.
B. It demonstrates the glenoid fossa and coracoid process to be able to see if the humeral head is anteriorly or posteriorly displaced.
FT
A: This view is the inferosuperior axial projection of the GH joint.
Routine Radiologic Evaluation: Axillary View of GH joint
Modified TF
A. This view can be used to determine the exact relationship of the humeral head to the glenoid fossa in GH dislocations.
B. The central ray is directed horizontally through the axilla toward the acromioclavicular joint with the patient in supine & SH abducted.
TT
Additional: The West point view is a variation of this view, with the patient in prone.
Routine Radiologic Evaluation: Anterior Oblique or Scapular Y Lateral
Modified TF
A. For this view, the patient is in a 70-degree posterior oblique position in standing.
B. The central ray is directed through the GH joint, perpendicular to the image receptor.
FT
A: For this view, the patient is in a 60-degree anterior oblique position in standing.
Routine Radiologic Evaluation: Anterior Oblique or Scapular Y Lateral
Modified TF
A. This view demonstrates the relationship of the humeral head to the glenoid cavity and also demonstrates the parts of the scapula projected clear of the rib cage.
B. The acromion and coracoid form the upper portion (limbs) of the Y appearance of the scapula, while the
scapular body forms the vertical portion of the Y.
TT
Fundamental Tenets of Musculoskeletal MRI
- T2 Fat Saturation
- Gradient Echo (GRE), Proton Density (PD)
A. Define anatomy
B. Detect abnormal fluid
- B
- A
Various Sequences or Protocols of MRI: Anatomy Sequence
- Axial
- Oblique sagittal
- Oblique coronal
A. T1
B. Proton density
- B
- A
- B
Various Sequences or Protocols of MRI: Fluid-Sensitive Sequence
- Axial
- Oblique sagittal
- Oblique coronal
A. Inversion recovery
B. T2 fat saturated
- B
- A
- A
Basic CT Scan vs Basic MRI Protocols for the Shoulder
- The most variable protocol
- From the top of the AC joint to the proximal humeral diaphysis, and from the scapular body out to the deltoid muscle
A. Basic CT Protocol
B. Basic MRI protocol
- B (Same area to be scanned as CT scan)
- A
Shoulder Region Structures Visualized by Routine Radiologic Evaluation
- Entire clavicle bilaterally
- AC Joint
- Upper lateral portion of scapula
- GH joint bilaterally as seen on AP view
A. AP external rotation
B. AP internal rotation
C. AP bilateral with & without weights / stress view
D. A and B only
- C
- D
- D
- C
Shoulder Region Structures Visualized by Routine Radiologic Evaluation
- Proximal 1/3 of humerus
- Sternoclavicular joint bilaterally
- Lateral 2/3 of clavicle
A. AP external rotation
B. AP internal rotation
C. AP bilateral with & without weights / stress view
D. A and B only
- D
- C
- D
The following are indications of CT scan for the shoulder, EXCEPT:
A. Severe trauma
B. Assessment of alignment and displacement of fracture fragments
C. Identification of loose bodies in the glenohumeral joint
D. Implanted cochlear hearing aids
E. None
D. Implanted cochlear hearing aids
Case: L.M. c/o pain when doing overhead activities. MD suspects labral or rotator cuff pathology & wants L.M. to undergo imaging evaluation. It was also noted on L.M.’s patient chart that they had a corrective scoliosis surgery in the past, where 12 screws were placed onto their spine (T8-L1). What imaging evaluation is best to use for L.M.’s case?
CT Scan
It is indicated for evaluation of labral or rotator cuff pathology, if MRI is unavailable or contraindicated
The following are indications of MRI for the shoulder, EXCEPT:
A. Rotator cuff tendon abnormalities, RC tears
B. Cysts, Superior Labrum Anterior-Posterior (SLAP) Lesions
C. For classification and staging of shoulder conditions
D. GH chondral abnormalities, osteochondral fractures, cartilage degeneration
E. None
E. None
The following are indications of MRI for the shoulder, EXCEPT:
A. Muscle atrophy, degeneration
B. Conditions affecting the Supraspinatus Outlet (Os acromiale, spurs)
C. Disorder of the long head of the biceps brachii (Tears, tendinopathy, subluxation, or dislocation)
D. Vascular Conditions (Aneurysms, stenosis)
E. None
E. None
Advanced Imaging Evaluation of the Shoulder
- Assess for occult fractures
- On axial view, assess the relationship of humeral head to glenoid fossa
- Check for bony injury from dislocation or trauma
A. Alignment of anatomy on CT Scan
B. Alignment of anatomy on MRI
- B
- A (For MRI, the humeral head should also sit in the middle of the glenoid fossa)
- B
Advanced Imaging Evaluation of the Shoulder
- Check for bony disruptions at tendon attachments
- On sagittal oblique view, check configuration of the acromion process
A. Alignment of anatomy on CT Scan
B. Alignment of anatomy on MRI
- B
- A
Advanced Imaging Evaluation of the Shoulder
- Assess for bone bruises or marrow edema seen as any hyperintense area in T2 weighted image
- Assess for any destruction, disease, or infection
- Assess for stress fractures
A. Bone Signal on MRI
B. Bone Density on CT Scan
- A
- B
- A
Advanced Imaging Evaluation of the Shoulder
- Assess for cysts, cortical hypertrophy and sclerosis (humeral head)
- Assess for osteochondral injuries
- Assess integrity of cortical (most dense) and cancellous (less dense) bone
A. Bone Signal on MRI
B. Bone Density on CT Scan
- B
- A
- B
Advanced Imaging Evaluation of the Shoulder
- Check for free fracture fragments
- Check for encroachment in subacromial space on oblique sagittal view
- Check for irregularities on AC joint surface
A. Edema on MRI
B. Cartilage/ Joint Spaces on CT Scan
- B
- B
- B
NOTE: Acromions that can cause impingement (hook type) can lead to encroachment in the subacromial space.
Advanced Imaging Evaluation of the Shoulder
- Assess smooth chondral surface of GH joint space on axial and sagittal cuts
- Check for edema under coracoacromial arch in impingement syndrome
A. Edema on MRI
B. Cartilage/ Joint Spaces on CT Scan
- B
- A
NOTE: In osteoarthritis, there is no smooth subchondral/chondral surface.
Advanced Imaging Evaluation of the Shoulder
- Check biceps tendon long head at bicipital groove
- Assess subacromial or subdeltoid bursa, it must have minimal or no fluid
- Synovial cysts from rheumatoid arthritis, large cuff tears
A. Soft tissue and synovial tissue on MRI
B. Soft tissues on CT Scan
- A
- A
- A
Advanced Imaging Evaluation of the Shoulder
- Assess continuity of RC muscles, increase in signal is due to inflammation at the tear site
- Check insertion of RC to bone for avulsion injuries, especially supraspinatus tendon
A. Soft tissue and synovial tissue on MRI
B. Soft tissues on CT Scan
- A
- B