Table of Contents

• General Principles
• Upper Extremity
  • Shoulder
  • Elbow (cast)
  • Elbow (no cast)
  • Wrist
  • DRUJ Instability

Table of Contents • Lower Extremity • Pelvis/Sacrum • Hip • Hip – Anteversion • Knee • Ankle • Hindfoot/Midfoot • Midfoot/Forefoot

GENERAL PRINCIPLES

General Principles • Proper Patient Positioning

• Patient comfort comes first, so may be difficult at times especially in cases of casting, fracture, or uncooperation
• Allows for easier reformats
• Reduces radiation dose to the patient • Reformats • Always include the entire field of view of the source images in the reformatted images • Soft tissue mass evaluation • Use palpable markers to bracket the area of palpable abnormality • Scan approximately 5 cm above and below the region of palpable abnormality • If study is ordered noncontrast, please check if patient can get intravenous contrast • Arthrograms • Dilute iodinated contrast with sterile saline or water in a 50/50 ratio

• Long Bone Protocol

General Principles

• Includes humerus, forearm, femur, and lower leg/extremity
• Cover entire long bone in the field of view and surrounding soft tissues to the skin surface
• Axial reformats perpendicular to the long bone diaphysis
• Sagittal and coronal reformats parallel to the long bone diaphysis
• Be sure to include entire source field of view in the reformats

UPPER EXTREMITY

Shoulder

• Positioning

Shoulder

• Patient supine with palm up

• Ideally, affected arm by side with contralateral arm raised above head
• If contralateral arm can’t be raised, position shoulder being scanned higher than other shoulder
• If not possible (i.e. acute trauma), do what you can to keep patient comfortable

Shoulder • Field of View

• Above acromioclavicular (AC) joint to just below scapula
• Medially to include scapula and laterally to skin surface
• Do not need to include the whole clavicle
• Include hardware if present • Scanning Parameters • 1.25 mm thick at 0.625 mm intervals

Shoulder • Sagittal and coronal reformats • 2 mm slice, 2 mm interval • Find axial image that shows glenohumeral joint (dashed line)

Shoulder

• Coronal reformats • 2 mm slice, 2 mm interval • Slices perpendicular to the glenohumeral joint line

• Sagittal reformats

• 2 mm slice, 2 mm interval

• Slices parallel to glenohumeral joint line

Shoulder

• Axial oblique reformats
• 2 mm slice, 2 mm interval

Shoulder

• Find coronal reformat image showing the acromion (red arrow)
• Orient slices perpendicular to the glenohumeral joint (dashed line)

Source axial

Reformat axial oblique*

Reformat coronal oblique*

Reformat sagittal oblique*

Shoulder CT Summary for fracture and bone lesion

PLANE

SECTION THICKNESS

1.25 mm

2 mm

2 mm

2 mm

INTERVAL

0.625 mm

2 mm

2 mm

2 mm

OVERLAP

50%

None

None

None

WINDOW

SOFT TISSUE

SOFT TISSUE BONE

BONE

BONE

*All reformats should include ENTIRE field of view of the source images

Shoulder CT Summary for CT Arthrogramⱡ or soft tissue mass/infection

Elbow (Cast)

• Most difficult to scan, particularly if in cast

• Obviously can’t straighten elbow but must try to get arm above head
• AVOID arm across chest • Causes beam hardening artifact, radiation to torso, and respiratory motion artifact
• Scanning plane should be obliquely oriented towards the long axis of the radius and ulna (don’t scan parallel to radius and ulna)

Elbow (Cast)

• Positioning

Elbow (Cast)

• Field of View • Distal humerus to proximal forearm (distal to radial tuberosity) • Scanning Parameters • 0.6 mm thick at 0.3 mm intervals

Elbow (Cast)

• Field of View • Distal humerus to proximal forearm (past radial tuberosity) • Scanning Parameters • 0.6 mm thick at 0.3 mm intervals

• Reformats

• 2 mm slice, 2 mm interval • Find sagittal image show elbow joint and olecranon (red arrow)

Elbow (Cast)

• Reformats

Elbow (Cast)

• 2 mm slice, 2 mm interval • Axial images perpendicular to long axis of humerus

• Reformats

Elbow (Cast)

• 2 mm slice, 2 mm interval • Axial images through long axis plane of forearm

Elbow (Cast) • Reformats • 2 mm slice, 2 mm interval • Long axis images to plane of the radius

Elbow (Cast) • Reformats • 2 mm slice, 2 mm interval • Coronal plane parallel to long axis of the ulna

Elbow (Cast)

• From axial series through the humerus, find an image through the medial and lateral epicondyles
• Note line parallel to the posterior border of the epicondyles

• Coronal reformats

• 2 mm slice, 2 mm interval • Coronal to humerus, parallel to inter-epicondyle line

Elbow (Cast)

• Sagittal Reformats

• 2 mm slice, 2 mm interval • Orient sagittal slices perpendicular to humerus and inter-epicondylar line

Elbow (Cast)

Cast Elbow CT Summary for fracture and bone lesion

Elbow (No Cast)

• Positioning • Most difficult to scan

Elbow (No Cast)

• Arm MUST be raised above patient’s head
• Should be as straight as possible with palm up
• If patient CAN’T straighten elbow, use CAST protocol
• AVOID arm across chest • Causes beam hardening artifact, radiation to torso, and respiratory motion artifact
• Scanning plane should be perpendicular to the CT scanning plane • Allows easier reformatting

• Positioning • Most difficult to scan

Elbow (No Cast)

• Arm MUST be raised above patient’s head
• Should be as straight as possible with palm up
• AVOID arm across chest • Causes beam hardening artifact, radiation to torso, and respiratory motion artifact
• Scanning plane should be perpendicular to the CT scanning plane • Allows easier reformatting

Elbow (No Cast)

• Field of View

• Distal humerus to proximal forearm (distal to radial tuberosity) • Scanning Parameters • 0.6 mm thick at 0.3 mm intervals

• Field of View

• Distal humerus to proximal forearm (distal to radial tuberosity) • Scanning Parameters • 0.6 mm thick at 0.3 mm intervals

Elbow (No Cast)

Elbow (No Cast)

• From axial series through the humerus, find an image through the medial and lateral epicondyles
• Note line parallel to the posterior border of the epicondyles

• Coronal reformats

• 2 mm slice, 2 mm interval • Coronal to humerus, parallel to inter-epicondyle line (red lines)

Elbow (No Cast)

• Sagittal Reformats

Elbow (No Cast)

• 2 mm slice, 2 mm interval • Orient sagittal slices perpendicular to humerus and inter-epicondylar line (red lines)

Noncasted Elbow CT Summary for fracture and bone lesion

Noncasted Elbow CT Summary for CT arthrogramⱡ and soft tissue mass/infection

Wrist

Wrist

• Positioning • Prone

• Arm over head and straight as possible with palm down
• Wrist centered in gantry • Scanning Parameters

• 0.625 mm thick at 0.3 mm intervals • Field of view • Proximal-Radius/Ulnametaphysis • Can scan more proximally to include extent of fracture • Distal – Past metacarpal bases

• Positioning • Prone

Wrist

• Arm over head and straight as possible with palm down
• Wrist centered in gantry • Scanning Parameters

• 0.625 mm thick at 0.3 mm intervals • Field of view • Proximal-Radius/Ulnametaphysis • Can scan more proximally to include extent of fracture • Distal – Past metacarpal bases

• Axial reformats

Wrist

• 1.5 mm thickness, 1.5 mm interval • Axial images through the radioulnar joint (red arrow)

• Sagittal reformats

Wrist

• 2 mm thickness, 2 mm interval
• Sagittal images through long axis of the wrist (perpendicular to axial reformats or along the long axis of the radius)

• Coronal reformats

Wrist

• 2 mm thickness, 2 mm interval
• Coronal images through long axis of the wrist (perpendicular to sagittal reformats)

Scaphoid Reformat • ADD if clinical history includes scaphoid pathology • oblique sagittal along long axis of scaphoid • 1 mm slice thickness, 1 mm interval

Wrist CT Summary for fracture and bone lesion

Wrist CT Summary for CT Arthrogramⱡ or soft tissue mass/infection

DRUJ INSTABILITY

DRUJ Instability • DRUJ = distal radioulnar joint • Positioning

• Prone with BOTH arms as straight as possible above head
• 3 separate images obtained of BOTH wrists in neutral, supine, and prone
• Keep both arms aligned with each other • Scanning Parameters

• Same field of view as routine wrist
• Only need axial images (but must be true axials as with routine wrist)

3 Separate Source axials (neutral/prone/supine)

Reformat axial NEUTRAL*

Reformat axial PRONE*

Reformat axial SUPINE*

Reformat bilateral coronal oblique

DRUJ Instability Summary

PLANE

SECTION THICKNESS

0.625 mm

2 mm

2 mm

2 mm

1 mm

INTERVAL

0.3 mm

2 mm

2 mm

2 mm

1 mm

OVERLAP

50%

None

None

None

None

WINDOW WIDTH/LEVEL

SOFT TISSUE

BONE

BONE

BONE

BONE

*-All reformats should include ENTIRE field of view of the source images

LOWER EXTREMITY

Pelvis/Sacrum

• Positioning • Patient supine

Pelvis

• Legs flat on table, avoid cushions under legs or feet • Field of View must include

• Above iliac crests (white line)
• Below lesser trochanter and ischial tuberosity (red line)
• Skin to Skin • Scanning Parameters

• 1.25 mm thick at 0.625 mm intervals

• Axial reformats

• 2 mm slice, 2 mm interval

Pelvis

• Coronal image that shows both femoral heads
• Angle such that slice cuts evenly through both femoral heads (dotted line)
• Coverage from iliac crests to below lesser trochanters ( solid lines)
• FAI (FEMORAL-ACETABULAR IMPINGEMENT): Include angled oblique axials through femoral necks (three solid lines)

• Coronal reformats

• 2 mm slice, 2 mm interval
• Axial image that shows pubic symphysis (red arrow)
• Angle evenly through ischial tuberosities (dotted line)

Pelvis

• Coverage from anterior aspect of the pubic symphysis to posterior to the musculature(solid lines)

• Sagittal reformats

• 2 mm slice, 2 mm interval
• Axial image that shows pubic symphysis (red arrow)

Pelvis

• Cover from hip to hip (solid lines)

Sacroiliac Joints

• Reformats

• 2 mm slice, 2 mm interval • Oblique Coronal • Mid-line Sagittal image through sacrum • Angle slices parallel to the long axis of sacrum (top image) • Cover sacrum in entirety, including entire sacroiliac joints • Oblique Axial

• Same mid-line Sagittal image through sacrum
• Angle slices perpendicular to the oblique coronals (bottom image)
• Cover sacrum in entirety, including sacroiliac joints

Source axial

Reformat axial*

Reformat coronal*

Reformat sagittal*

Reformat axial oblique femoral neck1

Reformat oblique coronal sacroiliac joints2

Reformat oblique axial sacroiliac joints2

Pelvis CT Summary for fracture or bone lesion

PLANE

SECTION THICKNESS

1.25 mm

2 mm

2 mm

2 mm

2 mm

2 mm

2 mm

INTERVAL

0.625 mm

2 mm

2 mm

2 mm

2 mm

2 mm

2 mm

OVERLAP

50%

None

None

None

None

None

None

WINDOW WIDTH/LEVEL

SOFT TISSUE

BONE SOFT TISSUE

BONE

BONE

BONE

BONE

BONE

*-Should include ENTIRE field of view of the source images 1-Perform if clinical history of FAI or femoroacetabular impingement 2-Perform if clinical history of sacroiliac/sacral pathology

Pelvis CT Summary for soft tissue mass/infection

Hip

Hip

• Positioning • Patient supine

• Legs flat on table, avoid cushions under legs or feet • Field of View must include

• Superiorly above iliac crest (white line)
• Inferiorly below lesser trochanter and ischial tuberosity (red line)
• Laterally to the skin surface (green line)
• Medially through the symphysis pubis (yellow line) • Scanning Parameters

• 1.25 mm thick at 0.625 mm intervals

PROSTHESIS: Hip

• Positioning • Patient supine

• Legs flat on table, avoid cushions under legs or feet • Field of View must include

• Superiorly above iliac crest (white line)
• Laterally to the skin surface (green line)
• Medially through the symphysis pubis (yellow line)
• Scan below hardware (red line) • Scanning Parameters • 1.25 mm thick at 0.625 mm intervals

• Axial and axial oblique reformats
• 2 mm slice, 2 mm interval

• Coronal image that shows femoral head
• Straight Axial: • Angle such that slice cuts evenly through the superior femoral head (dotted line) • Coverage from above iliac crest to below lesser trochanters (red lines)
• FAI (FEMORAL-ACETABULAR IMPINGEMENT): Include angled oblique axials through femoral necks (solid yellow lines)

Hip

• 2 mm slice, 2 mm interval
• Axial image that shows anterior acetabulum (red arrow)
• Angle evenly through anterior acetabulum (dotted line)

Hip

• Coronal reformats

• Cover from skin to skin (red lines)

• Sagittal reformats

Hip

• 2 mm slice, 2 mm interval

• Same axial image as the coronal reformats
• Angle perpendicular to coronal plane (dotted yellow line)
• Cover entire field of view (red lines)

Hip CT Summary for fracture or bone lesion

Hip CT Summary for CT arthrogramⱡ or soft tissue mass/infection

Hip - Anteversion

Hip - Anteversion

• Positioning • Patient supine

• Legs flat on table and as close together as possible
• tape feet together with toes pointed straight up
• avoid cushions under legs or feet • Scout • AP plane • Hips and Knees • Scanning Parameters

• 5.00mmthickat5.00mmintervals
• Hips – just above femoral heads and to just below lesser trochanters
• Knees – just above femoral physis and thru tibial plateau

Hip - Anteversion • Find slice that best reveals alignment of femoral neck • Measure the neck – horizontal angle (NH) • Find the slice that best reveals alignment of femoral condyles • Measure the condyle – horizontal angle (CH) • Calculate angle of neck relative to condyle (NC = NH – CH)

Hip - Anteversion • Find slice that best reveals alignment of femoral neck • Measure the neck – horizontal angle (NH)

Hip - Anteversion • Find the slice that best reveals alignment of femoral condyles • Measure the condyle – horizontal angle (CH)

Hip - Anteversion • Calculate angle of neck relative to condyle (NC = NH – CH)

Knee

Knee

• Positioning • Patient supine

• Slide patient so that knee being imaged is centered in the scanner
• Tapping toes together may help positioning
• Can scan both legs together, but if other leg has metal MUST bend so it is not in the scanning plane

• Field of View must include

• Entire patella
• Both femoral condyles

• Proximal tibia to just past the fibular head
• METAL PROSTHESIS: Must scan entire length of the femoral and tibial components • Scanning Parameters • 0.625 mm thick at 0.3 mm intervals

Knee

• Axial reformats

• 2 mm slice, 2 mm interval

• Coronal image that shows tibial plateaus (solid line)
• Angle such that slice cuts evenly through tibial plateaus (dotted lines)
• Coverage from femoral metaphysis to below fibular head

Knee

Knee • Coronal • 2 mm slice, 2 mm interval • Axial image that shows distal patella • Angle such that slice are parallel to a line connecting the posterior aspect of the femoral condyles (dotted line)

• Sagittal

• 2 mm slice, 2 mm interval

Knee

• Axial image that shows distal patella (same image as for coronal reformats)
• Angle such that slice are parallel to the coronal reformats

Knee CT Summary for fracture or bone lesion

Knee CT Summary for CT arthrogramⱡ or soft tissue mass/infection

Ankle

• Positioning • Patient supine

Ankle

• Use foot holder
• Feet together, centered in scanner
• Toes pointing straight up
• Typically scan both feet together (if can’t bring feet together, ensure imaged foot is centered in gantry) • Scanning Parameters • 0.625 mm thick at 0.3 mm intervals

Ankle

• Field of View must include • Start above ankle joint just above tibial metaphysis • Include calcaneus and metatarsal bases

• Axial reformats

• 2 mm slice, 2 mm interval

• Find sagittal image of tibiotalar joint (dotted yellow line)
• Orient slices parallel to the tibiotalar joint (solid yellow lines)

Ankle

• Coronal reformats

• 2 mm slice, 2 mm interval

• Find tibiotalar joint on axial image (same level as sagittal reference image)
• Orient slices parallel to the joint

Ankle

• Sagittal reformats

• 2 mm slice, 2 mm interval

• Find tibiotalar joint on axial image (same level as sagittal reference image)
• Orient slices perpendicular to the joint

Ankle

Ankle CT Summary for fracture or bone lesion

Source axial

Reformat axial*

Reformat coronal*

Reformat sagittal*

PLANE

SECTION THICKNESS

0.625 mm

2 mm

2 mm

2 mm

INTERV AL

0.3 mm

2 mm

2 mm

2 mm

OVERLA P

50%

None

None

None

WINDOW WIDTH/LEVEL

SOFT TISSUE

BONE SOFT TISSUE

BONE

BONE

*All reformats should include ENTIRE field of view of the source images

Ankle CT Summary for CT arthrogramⱡ or soft tissue mass/infection

Hindfoot/Midfoot

Hindfoot/Midfoot • Appropriate for Hindfoot fractures (calcaneus, talus), subtalar joint evaluation, tarsal coalition • Positioning

• Patient supine
• Use foot holder
• Feet together, centered in scanner
• Toes pointing straight up
• Typically scan both feet together (if can’t bring feet together, ensure imaged foot is centered in gantry) • Scanning Parameters • 0.625 mm thick at 0.3 mm intervals

Hindfoot/Midfoot • Field of View must include • Start above ankle joint just above tibial metaphysis • Include calcaneus and metatarsal bases

• Axial reformats

• 2 mm slice, 2 mm interval
• Find sagittal image of tibiotalar joint (dotted yellow line)
• Orient slices parallel to the tibiotalar joint (solid yellow lines)

Hindfoot/Midfoot

Hindfoot/Midfoot • Axial oblique reformats

• 2 mm slice, 2 mm interval
• Find sagittal image of posterior facet subtalar joint (dotted yellow line)
• Orient slices parallel to the posterior facet subtalar joint (solid yellow lines)

Hindfoot/Midfoot • Coronal oblique reformats • 2 mm slice, 2 mm interval • Orient slices perpendicular to axial oblique reformats

Hindfoot/Midfoot • Straight sagittal reformats • 2 mm slice, 2 mm interval • Orient parallel to axial reformats

Hindfoot/midfoot CT Summary for fracture or bone lesion

Source axial

Reformat axial*

Reformat axial oblique*

Reformat coronal oblique*

Reformat sagittal*

PLANE

SECTION THICKNESS

0.625 mm

2 mm

2 mm

2 mm

2 mm

INTERV AL

0.3 mm

2 mm

2 mm

2 mm

2 mm

OVERLA P

50%

None

None

None

None

WINDOW WIDTH/LEVEL

SOFT TISSUE

BONE SOFT TISSUE

BONE

BONE

BONE

*All reformats should include ENTIRE field of view of the source images

Hindfoot/midfoot CT Summary for soft tissue mass/infection

Source axial

Reformat axial*

Reformat axial oblique*

Reformat coronal oblique*

Reformat sagittal*

PLANE

SECTION THICKNESS

0.625 mm

2 mm

2 mm

2 mm

2 mm

INTERV AL

0.3 mm

2 mm

2 mm

2 mm

2 mm

OVERLA P

50%

None

None

None

None

WINDOW WIDTH/LEVEL

SOFT TISSUE

BONE SOFT TISSUE

SOFT TISSUE

SOFT TISSUE

SOFT TISSUE

*All reformats should include ENTIRE field of view of the source images

Midfoot/Forefoot

Midfoot/Forefoot • Appropriate for Lisfranc fracture/dislocation, metatarsal fractures • Positioning

• Patient supine
• Use foot holder
• Feet together, centered in scanner
• Toes pointing straight up
• Typically scan both feet together (if can’t bring feet together, ensure imaged foot is centered in gantry) • Scanning Parameters • 0.625 mm thick at 0.3 mm intervals

Midfoot/Forefoot • Field of View must include • Start from distal talonavicular joint to beyond the toes

Midfoot/Forefoot • Reformats (2 mm slice, 2 mm interval) • Relative to 2nd Metatarsal • LONG AXIS OBLIQUE

Midfoot/Forefoot • Reformats (2 mm slice, 2 mm interval) • Relative to 2nd Metatarsal • SHORT AXIS OBLIQUE

Midfoot/Forefoot • Reformats (2 mm slice, 2 mm interval) • Relative to 2nd Metatarsal • SAGITTAL

Midfoot/forefoot CT Summary for fracture or bone lesion

Midfoot/forefoot CT Summary for soft tissue mass/infection

References • University of Wisconsin CT protocols https://www.radiology.wisc.edu/sections/msk/protocols.php • Thomas Jefferson University http://www.bone.tju.edu/protocols.htm