Diagnostic Imaging in Musculoskeletal Injuries

1
Diagnostic Imaging in Musculoskeletal Injuries

• Rodney S. Gonzalez, MD
• Primary Care Sports Medicine Fellow
• Contributors
• Leslie Rassner, MD (Slides adapted from)
• Francis OConnor, MD, FACSM
• Ulrich Rassner, MD

2
Objectives

• Discuss fundamental imaging strategies for the
  evaluation of site-specific musculoskeletal
  injuries.
• Review the various imaging modalities available
  to the clinician with an emphasis on
• Indications
• Limitations
• Contraindications

3
Low Back Pain

• Healthy middle age male with acute onset of low
  back pain after pick-up basketball game.
• Adolescent female gymnast with gradual onset of
  low back pain.
• Middle age obese patient with history of
  prolonged oral steroid use and multiple
  co-morbidities s/p car accident with back pain.

4
Low Back Pain

• Who will you x-ray?
• What plain film views do you want?
• When do you order a CT, MRI or CT myelogram?
• When will you order a bone scan?

5
Low Back Pain

• Make a pathoanatomic diagnosis or differential
  diagnosis.
• Decide do we need to rule out tumor, infection,
  or fracture?
• Would imaging change our treatment such as
  generate referral to surgeon or for epidural
  steroid injection?

6
Low Back Pain

• Image red flag patients
• Major trauma
• Age gt 50
• Unrelenting pain at rest or night pain
• Fever, chills, sweats
• Unexplained weight loss
• History of cancer
• Incontinence of bowel or bladder
• Progressive weakness

7
Low Back Pain

• Conventional x-ray (plain films)
• AP, lateral, and lumbosacral (LS) spot view
• LS spot view
• L5 centered view eliminates
  potential over-read of disk
  space narrowing from beam
  diversion on standard lateral
• Initial view to look for disk space
  narrowing, osteophytes, fracture,
  tumor, or spondylolisthesis

8
Low Back Pain

• Conventional x-ray (plain films)
• Oblique views best if concern for pars
  interarticularis stress fracture (spondylolysis)
• Pars interarticularis narrow portion of bone
• between the superior and inferior articular
  facets

9
Radiography

• Advantages
• Inexpensive
• Readily available
• Excellent spatial resolution
• Real-time availability as fluoroscopy

10
Radiography

• Limitations
• Two-dimensional
• Relatively poor soft tissue contrast resolution
• However,
• Useful for radio-opaque foreign bodies
• Useful for soft tissue emphysema or free air
• Ionizing radiation exposure

Two orthogonal views at a minimum
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Inservice Question X-ray

• A 23-year-old male returns from a Florida beach
  vacation, where he sustained a cut to his foot
  while wading.
• The cut wasnt treated when it happened, and it
  is healing, but he says that it feels like
  something in the wound is poking him.
• Of the following, which one would most likely be
  easily visible on plain film radiography?
• A) A wood splinter
• B) A glass splinter
• C) A plastic splinter
• D) A sea urchin spine

12
Radiography

• Contraindications
• Pregnancy
• Most of concern for L-spine and pelvis.
• Other areas minimal radiation exposure to fetus
  with shielding.

13
Low Back Pain

• Our middle age patient had no red flags. We
  diagnosed him with mechanical low back pain and
  started him on conservative treatment.
• Six weeks out patient has no improvement in his
  pain. He has symptoms of sciatica. He has
  normal x-rays.
• You feel an epidural steroid injection is
  indicated.
• What imaging study is next?
• MRI?
• CT?
• CT myelogram?

14
Low Back Pain

• MRI
• Excellent for disk herniation and cord contusion
• Also will demonstrate
• Spinal cord anomalies
• Tumors
• Discitis
• Vertebral osteomyelitis

15
Magnetic Resonance Imaging

• Vast, vast majority of clinical MRI utilizes the
  magnetic moment of hydrogen nuclei (protons).

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Magnetic Resonance Imaging

• Advantages
• Superior contrast resolution, particularly among
  soft tissues.
• High degree of sensitivity in diseases involving
  bone marrow.
• Non-ionizing radiation (instead electromagnetic
  radiation).

17
Magnetic Resonance Imaging

• Limitations
• The most artifacts motion and metal.
• Claustrophobia.
• Some findings are extremely subtle, can be highly
  dependent upon interpretation (ie.
  glenohumeral labral pathology).
• High cost.

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Magnetic Resonance Imaging

• Contraindications
• Pacemakers absolute (under investigation)
• Devices may malfunction or be contraindicated
• Cardiac valves usually safe after 6 weeks
• Stents
• Non-ferromagnetic are safe
• Ferromagnetic are safe after 6 weeks due to
  epithelialization
• Abdominal aortic aneurysm stents, check with
  radiologist
• Pumps, check with radiologist
• Get radiologists approval documented in the chart

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Magnetic Resonance Imaging

• Contraindications (continued)
• Metal foreign bodies, body piercings, and jewelry
  can migrate, heat up, or torque.
• Situational clearance
• Fragment in brain or eye in vast majority
  contraindicated.
• Bullet imbedded in femur or extremity muscle,
  likely OK.
• Tattoos and cosmetics can
  heat up (metallic dyes)

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Magnetic Resonance Imaging

• Contraindications (continued)
• Obese patients
• Scanner table weight limits
• The gantry opening might be too small even if
  patient qualifies by weight
• Pregnancy
• Avoid 1st trimester
• No gadolinium unless absolutely necessary
• Animal studies conflicting

21
MRI-Safety

• The field of the scanner is ALWAYS on.
• Everything that is sucked into the magnet goes
  into the center, where the patient is lying.
• Disregard for safety procedures can potentially
  be lethal.

22
Low Back Pain

• Patient has a pacemaker and some cool tattoos.
  His back pain is not improving and he has
  physical exam findings of nerve impingement.
• What study can you do?

23
Low Back Pain

• CT Scan
• Excellent for delineating bone if concern for
  vertebral fracture with posterior fragment
  displacement (would likely be done in conjunction
  with MRI)
• CT Myelogram
• Fluoroscopic guided lumbar puncture with
  placement of non-ionic contrast
• Indications
• You are an old-fashioned doctor
• Contraindication to MRI (or no access to MRI)
• Evaluate nerve root cysts, can determine
  communication of multiple cysts by contrast fill
  pattern
• Carries risks of invasive procedure

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Computed Tomography

• CT uses x-rays to produce cross sectional images.
• Sir Godfrey Newbold Hounsfield
• Built first clinically utilized CT- (brain)
  scanner
• Nobel prize in medicine 1979, shared with Allan
  Cormack

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Computed Tomography

• CT is cool!
• Images reconstruction - 2D or 3D.
• Kinematic CT - imaging of joint motion.

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Computed Tomography

• Advantages
• Higher contrast resolution of images
• Excellent images of bones and lungs
• IV contrast rarely needed for orthopedic trauma
  (unless soft tissue/organ injury workup)
• Wide availability

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Computed Tomography

• Limitations
• Can produce artifacts motion and metal
• More limited soft-tissue contrast than MRI
• Not as good as ultrasound for superficial
  structures like rotator cuff or Bakers cyst
• Ionizing radiation
• Radiation dose much higher than for conventional
  radiography
• Higher cost than conventional x-ray

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Computed Tomography

• Contraindications
• Scanner weight limits for obese patients
• Pregnant women should not have CT scans except in
  life-threatening emergencies
• Pregnant patients can be scanned with shielding
  depending on body part (minimal radiation
  exposure to fetus if ankle or knee is scanned)

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Low Back Pain

• Our adolescent gymnast has a pars
  interarticularis defect on LS spot view. We want
  to decide whether she needs back bracing.
• We have a 20 y.o. male service academy athlete
  with low back pain, worse on single leg extension
  test, but without plain film abnormality.
• What diagnosis are you concerned about?
• You have plain
• filmswhat next?

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Spondylolysis

• Defect in pars interarticularis
• Result from congenital, degenerative, traumatic,
  or stress-related causes.
• Approximately 5 of Caucasians have on x-ray
• Can occur with repetitive mechanical loading
• Increased incidence in football linemen and
  gymnasts

31
Scintigraphy/Bone Scan

• Biologically active drugs are labeled with
  radioisotopes
• The images produced by scintigraphy are a
  collection of radiation emissions obtained with a
  special camera (gamma camera)
• Two principal techniques in sports medicine
• Planar (traditional bone scan)
• SPECT cross-sectional

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SPECT Imaging Single Photon Emission Computed
Tomography
Coronal
Sagittal
Axial
Posterior planar image

• Enhanced tissue contrast
• Improved sensitivity and specificity of lesion
  detection
• and localization

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Scintigraphy

• Advantages
• Ability to image metabolic activity
• Very sensitive to fractures and tumors

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Scintigraphy

• Limitations
• Lacks of significant detail
• Poor spatial resolution
• Poor specificity
• Displays function of osteoblasts
• Old fractures (pars defects) may not show up.
• Certain tumors with little osteoblastic activity
  (multiple myeloma and lytic mets) not reliably
  seen.

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Scintigraphy

• Contraindications
• Exposes patient to ionizing radiation
• Children and pregnant women should be carefully
  screened

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Spondylolysis

• X-ray
• Cheap, but low sensitivity
• Not physiologic, does not determine if active
  healing
• Can be used for monthly f/u for observation of
  healing
• Scintigraphy
• Bone scan fairly sensitive, not as specific,
  and does not show detailed anatomy
• SPECT scan greater accuracy than bone scan and
  x-ray, but expensive and not as readily available
• Can not be used to follow progression of healing
  as will stay positive one year
• Thin section CT scan
• Sensitive and shows anatomic detail
• Must know level of concern to focus imaging

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Spondylolithesis

• Forward slippage of one vertebral body on another
  due to bilateral pars defects at a given
  vertebral level
• Hot on bone scan, refer
• Cold on bone scan, refer only
  if slip gt 25 ( gt Grade 1) for
  consideration of
  thoracolumbosacral orthosis
  (TLSO) or surgical stabilization

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Chronic Low Back Pain

• Consider guided injections
• Fluoroscopic SI, facet injections, epidural
  steroids

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Fluoroscopy

• Real-time x-ray images with digital detectors.
• X-ray source is underneath table and detector
  above, thus shield needs to be placed underneath
  patient.

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Questions?
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Cervical Spine Injuries

• All patients with suspected fracture need three
  views
• Cross-table lateral
• Anteroposterior (AP)
• Open-mouth odontoid

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Cervical Spine Injuries

• Systematic review of cervical spine radiographs
• Lateral view
• All vertebrae on the lateral
• Presence of lordosis
• Vertebral alignment
• Spinolaminal line
• Spinous processes
• Soft tissue examination

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Cervical Spine Injuries

• Systematic review of cervical spine radiographs
• Lateral view
• All vertebrae on the lateral
• Presence of lordosis
• Vertebral alignment
• Spinolaminal line
• Spinous processes
• Soft tissue examination

44
Cervical Spine Injuries

• Soft tissue space r/o occult fracture
• 6 at 2 and 2 at 6
• 6mm at C2 and 2cm at C6
• C1-C3 lt 7mm
• C4-C7 14-22 mm

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Cervical Spine Injuries

• Systematic review of cervical spine radiographs
• AP view
• Spinous processes

46
Cervical Spine Injuries

• Systematic review of cervical spine radiographs
• Odontoid view
• C1-2 articulation

Jefferson fracture ring of C1 broken in 4
places from axial loading
47
Cervical Spine Injuries

• Dynamic flexion-extension
• Expose undetected ligament disruption
• Indicated if initial films normal, but suspicion
  persists
• Require alert, cooperative patient, stopping for
  pain or paresthesias

48
Cervical Spine Injuries

• Dynamic flexion-extension
• Widening of the predental space from rupture of
  the transverse ligament.
• Ligament normally holds C-1 against the dens
  (odontoid) of C-2.

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Cervical Spine Injuries

• CT
• If suspicion high but plain films normal
• If signs of possible instability on plain films
• Better visualize fracture, evaluate for
  displacement
• MRI
• To clearly define canal compromise and/or soft
  tissue injury

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Inservice Question Head

• A 15-year-old white male is being evaluated after
  a fall down one flight of stairs.
• He walked briefly at the scene and did not lose
  consciousness.
• His only complaint is a mild, generalized
  headache. One episode of vomiting occurred
  shortly after the accident. No weakness or
  numbness has been noted.
• Vital signs, mental status, and neurologic
  findings are normal.
• Radiologic evaluation of the cervical spine is
  remarkable only for an air-fluid level in the
  sphenoid sinus.
• Which one of the following abnormalities is most
  likely to be associated with this radiologic
  finding?
• A) A basilar skull fracture
• B) An orbital floor fracture
• C) An epidural hematoma
• D) A zygomatic arch fracture
• E) A mandible fracture

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Questions?
52
Shoulder Injuries
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Acute Shoulder Trauma

• Acute series
• Obtained with patient as is, without moving arm
  or sling. Patient can be standing, sitting, or
  lying.
• AP
• Lateral scapular view

54
Shoulder Injury

• Standard series
• Internal and external rotation AP
• Axillary view

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Shoulder Injury

• Views
• True AP
• Arm held in slight internal rotation
• Identify greater tuberosity fractures
• Hill-Sachs lesion
• Impression defect on
  posterolateral aspect
  of humeral head
• Can miss posterior
• dislocation

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Shoulder Injury

• Views (continued)
• Supraspinatus outlet view, scapular lateral view,
  or Y view
• Direction of dislocation and angulation of
  proximal humerus fractures
• Good view when patient discomfort/injury prevents
  axillary view
• Axillary views
• Acromial and coracoid fractures

57
Shoulder Injury

• MRI and MRI arthrography
• Nonsurgical diagnostic test of choice for
  internal derangements and structural instability
  assessment
• Soft tissue and bone lesions well demonstrated

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Shoulder Impingement - Instability

• Labral Pathology
• MRI with gadolinium - a must for labral pathology
• CT arthrography

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Shoulder Injury

• Scintigraphy
• Indications rare
• Screening
• Stress reaction of the bone
• Osteochondrosis Little League
  Shoulder
• Bone tumors

60
Inservice Question - Shoulder

• A 70-year-old white female asks you to evaluate
  her right shoulder because of pain and limited
  motion.
• Two months ago she remembers catching herself
  while holding the refrigerator door handle when
  she slipped on a wet floor.
• She demonstrates pain and weakness at 45 of
  abduction and weakness on external rotation.

She should be treated for A) Bicipital
tendinitis B) Disruption of the glenoid fossa
C) Rotator cuff tear D) Acromioclavicular
separation E) Incomplete fracture of the humeral
head
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Questions?
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Wrist Injury
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Wrist Injury

• Standard views PA and lateral
• PA view
• Constant 2 mm intercarpal
  joint space
• 3 arcs
• Lateral view
• 4 Cs

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Wrist Injury
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Scapholunate Dissociation
66
Perilunate Injury
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Lunate Dislocation
68
Radiography

• Complex Joints may require additional views

Anatomic Snuff Box Tenderness
Scaphoid Fracture
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Wrist Injury

• Scaphoid fracture
• Scaphoid view
• If negative, immobilization for 2 to 3 weeks,
  followed by repeat films
• If negative and symptomatic, limited MRI

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Chronic Wrist Pain

• Hamate Fracture
• CT scan
• Keinbocks Disease
• X-ray, bone scan, MRI
• Carpal Instability
• X-ray angles, MR
  arthrogram

• TFCC Injury
• MR arthrogram
• Occult Ganglion
• MR arthrogram
• Complex Regional Pain Syndrome
• Bone scan delayed periarticular uptake

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Inservice Question - Wrist

• A 20-year-old white male presents to your office
  after a fall on an outstretched hand while
  skateboarding.
• He has pain at the anatomic snuffbox with no
  abrasion.
• Radiographs are negative.
• Which one of the following would be the most
  appropriate management?
• A) A long arm cast for 8 weeks
• B) A thumb spica splint and follow-up radiographs
  in 2 weeks
• C) A sugar tong splint and follow-up radiographs
  in 2 weeks
• D) An Ace bandage and follow-up radiographs in 2
  weeks
• E) An Ace bandage and follow-up in 2 weeks if the
  patient is still experiencing pain

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Questions?
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Hip Pain/Injury

• X-ray
• Good place to start
• Check for arthritis and avascular necrosis
• Can miss grade 4 cartilage damage
• May repeat hip x-rays early as one month as can
  have significant interval degenerative change
• Initial evaluation femoral neck for stress
  fracture

74
Hip Pain/Injury

• MRI
• Need strong magnet (1.5 tesla) and surface coil
• Bad for cartilage
• 42 false negative for cartilage damage, but may
  show indirect findings
• Good for diagnosis and localization of femoral
  neck stress fractures

75
Hip Pain/Injury

• MRA
• Good at finding labral pathology
• Increased sensitivity, but also
  increased false positive
• Sequence for gadolinium can
  obscure bone pathology
• Get ANESTHETIC injection with contrast!
• Relief of pain with intraarticular MRA anesthetic
  may give more information than study

76
Hip Pain/Injury

• Iliopsoas Bursography (Fluoscopic)
• Can diagnosis snapping hip caused by iliopsoas
  tendon
• flexion to extention reproduces
• Can be followed by therapeutic corticosteroid
  injection of bursa
• Can be difficult to visualize due to C-arm
  getting in way of hip motion
• Ultrasound
• Non-invasive, can compare sides
• Requires excellent technician and advanced
  ultrasound machine

77
Inservice Question - Hip

• A 19-year-old female runner has a 1-week history
  of constant groin pain.
• There is limited hip motion on flexion and
  internal rotation of the right hip.
• Radiographs of the hip and pelvis are normal.
• Which one of the following is the most likely
  diagnosis?
• A) Iliotibial band syndrome
• B) Stress fracture of the right femoral neck
• C) Osteitis pubis
• D) Pelvic inflammatory disease

78
Questions?
79
Knee Injury
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Acute Knee Trauma

• AP, lateral 30o flexion

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Acute Knee Trauma

• Value of cross table lateral
• Rule out fracture
• Can reveal fat-fluid level in joint
  (lipohemarthrosis)

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Segond sign
Small lateral capsular bony avulsion lateral to
the tibia at the level of the joint
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Acute Knee Trauma

• Advanced imaging
• CT scan for complex fractures
• MRI for soft tissue

- MRI imaging modality of choice - T2 weighted
images - pathology sequence
84
Chronic Knee Series

• X-rays
• Lateral
• Sunrise/Merchant
• PA/axial/tunnel
• AP weight bearing

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Chronic Pain/Instability

• X-ray
• 45o weight bearing flexion PA
• Weight bearing AP on long cassette
• MRI
• Meniscal injury
• Ligamentous insufficiency
• Osteochondral injury

86
Questions?
87
Leg Pain

• Exertional leg pain differential diagnosis
• Shin splints
• Stress fracture
• Exertional compartment syndrome
• Popiteal artery entrapment syndrome

88
Exertional Leg Pain

• Shin Splints
• Clinical diagnosis
• Plain films to r/o stress fracture
• Triple Phase Bone Scan
• Phase
• Blood flow and Pool only classically no uptake
  on delayed images.
• Appearance
• Linear not fusiform

Arrows stress fracture Arrowheads periostitis
89
Scintigraphy

• Triple phase bone scan
• Flow (perfusion) study
• 60 seconds after injection
• Blood flow
• Blood Pool
• Increased circulation, blood vessel dilation
• Delayed
• 2 -3 hrs after injection
• Bone uptake (clearance from extraosseous tissues)

90
Stress (Overuse) Fractures

• Initial radiograph normal in up to 70 of
  athletes at onset of pain
• Fluffy, ill-defined sclerotic line perpendicular
  to major trabecular lines

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Stress (Overuse) Fractures

• Thin incomplete lucent line
• May proceed to completion
• Periosteal reaction

92
Imaging of Early Stress Fractures

• MRI and bone scan near 100 sensitivity
• MRI improved specificity

93
Chronic Exertional Compartment Syndrome

• Triple phase bone scan and MRI have not been
  shown to be reliable to date to replace clinical
  judgement with compartment pressure testing.
• Samuelson DR, Cram RL The three-phase bone scan
  and exercise induced lower-leg pain the tibial
  stress test. Clin Nucl Med 199621(2)89-93.

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Popliteal Artery Entrapment Syndrome

• MRA with and without plantarflexion
• Some experienced ultrasound technicians able to
  examine
• Angiography

95
Questions?
96
Ankle Injury
97
Acute Ankle Trauma

• When do you x-ray?
• Ottawa Ankle Rules

Stiell IG, McKnight RD, Greenberg GH, McDowell
I, Nair RC, Wells GA, et al. Implementation of
the Ottawa ankle rules. JAMA 1994271827-32.
98
Dont forget the foot films!

• AP, lateral and oblique
• Contralateral foot films
• Weight-bearing views

• On the lateral, metatarsal shaft and tarsal bone
  align
• On AP and obliques, the 2nd met medial border
  and middle cuneiform align

99
Chronic Ankle Pain

• Chronic ankle pain
• MRI is thought to be the imaging modality of
  choice for ligamentous injuries
• Impingement lesions, tendon problems,
  osteochondral lesions
• CT is good for ankle fractures/bony pathology
• Occult fractures
• Consider bone scan for diffuse non-specific pain
  with F/U CT if needed for superior bone
  resolution
• Stress fractures

100
Questions?
101
Ultrasonography
102
Ultrasonography

• Ultrasound uses high-frequency sound waves to
  produce images.
• Can define masses and localize foreign bodies.
• MSK use very popular in Europe and Australia.

103
Ultrasonography - Tendons

• Tendon evaluation (Achilles, patellar, rotator
  cuff)

Normal Achilles Tendon
- Normal tendon bright structure with
longitudinally oriented bundles
Chronic Tendonopathy
- Blurring, thickening, loss of normal
architecture
104
Ultrasonography - Muscles
- Gastrocnemius with hematoma
-Torn rectus femoris muscle

• Dynamic evaluation of
• rectus femoris
• - Complete disruption of fibers

105
Conclusions

• The initial imaging of choice
  remains plain radiography.
• CT is good for bone.
• MRI is good for soft tissue.
• Scintigraphy is good for finding a process with
  metabolic activity, or determining metabolic
  activity.
• Ultrasound will (hopefully) increasingly be used
  in musculoskeletal imaging as operator and
  interpreter skills increase.
• Advanced imaging selection is based upon your
  history and physical, knowing your specialists
  imaging preferences, and consultation with your
  regional radiologist as needed.

106
Thank You
Questions?