Diagnostic imaging

Positioning anatomy
-What does each accessory view show you/why is it done?
-What anatomy is best seen on:
-Anterior oblique cervical view (obliques show IVFs, which one?)
-Posterior oblique cervical view
-Anterior oblique lumbar view (obliques show pars, which one?)
-Posterior oblique lumbar view

Positioning tube tilts
-Cervical views with tube tilts
-APLC: 15˚ cephalic
-Anterior oblique: 15˚ caudal (down a cute butt)
-Posterior oblique: 15˚ cephalic (up a cute face)
-Swimmer’s view: sometimes 5˚ caudal
-Pillar view: 35˚ cephalic
-Thoracic views: no tube tilts, but these views are unique b/c they use compensating filters
-Lumbar/pelvic/sacrum views with tube tilts
-Frontal angulated L5-S1 (AP L5-S1 spot): 30˚ cephalic
-AP sacrum (tilt up view): 15˚ cephalic
-Upper extremities:
-wrist: scaphoid view: 20˚ cephalic
-all extremity views that have tube tilts are cephalic tube tilts
-Lower extremities:
-knee (not patella)
-AP knee: 5˚ cephalic
-Lateral knee: 5˚ cephalic
-“nickel knee shots”
-patella: tangential/sunrise/skyline/prone Settegast view: 10˚ cephalic (sun rises at 10 am in radiology)
-AP (dorsal plantar view): 10˚ cephalic
-Medial oblique: 10˚ cephalic
-patient has 10 toes visible on these 2 views

Positioning FFD = TFD
-focus to film distance or tube to film distance
-all extremities start at 40″ TFD and are only modified if a tube tilt is present
-formula: for every 5˚ of tube tilt, subtract 1 inch of TFD
-starting TFD minus (tube tilt/5) = TFD
-all spinal views have starting TFD of 40″ except these (starting at 72″): LCN, anterior and posterior oblique, cervical flexion, cervical extension (cervical air-gap rule), AP full spine (Gonstead)
-the same formula applies to all spinal views

Positioning grids
-all spinal views need a grid/bucky except cervical view with starting TFD of 72″ (air gap rule)
-even though these views don’t need a grid, you can still use one
-all extremities above the elbow need a grid (everything below elbow and elbow itself does not need grid)
-all extremities above the knee need a grid
-knees may need a grid of they measure larger than 11-13 cm

Positioning breathing instructions
-extremities/cervical: don’t move or don’t move, don’t breathe
-above the diaphragm (thoracic, ribs 1-9): breathe all the way in and hold
-below the diaphragm (lumbar, pelvis, ribs 10-12): breathe all the way out and hold

Positioning patient positioning
-look at the name for clues
-general rule: the name will tell you what side and what part of the patient is touching the cassette/grid
-exceptions: lateral views of an upper extremity (these are placed w/ the medial side touching the cassette/grid)

Positioning central ray
-look at the name: scaphoid view: CR goes through the scaphoid
-imagine the entire body part; CR usually goes through the center of that body part
-specific views
-thoracic, chest, ribs 1-9: set film height, then center CR to film
-film height = 1-2 inches above C7/vertebral prominens

Positioning random facts
-swimmer’s view is controversial in terms of TFD, tube tilt, film size, and collimation; it is taken to see the cervicothoracic junction
-lateral elbow view is performed w/ the patient elbow bent at 90˚ and thumb up
-all chest views are taken at 72″ TFD and are above diaphragm
-chest views are only views with 100 or more kVp
-gonad shields are not used if they obscure anatomy
-10 day rule for pregnancy


􀁸 Inflammatory arthritides

􀁸 X-ray signs:

􀁸 The earliest sign of AS is called the romanus lesion. At the corner of the vertebra there is an erosion of a bone (very subtle, usually can’t see it on x-ray). But if it undergoes calcification and is called “the Shiny corner sign” (is technically the earliest x-ray sign).

􀁸 Once AS starts to form once you see the marginal syndesmophytes they must bilateral and symmetrical. “Bamboo spine” appearance.

􀁸 “The trolley track sign”: due to calcification of the capsular ligaments

􀁸 “The dagger sign”: due to calcification of supraspinous and interspinous ligaments

􀁸 “The star sign”: is only seen when you have fusion of the SI joints

􀁸 “The ghost joints”: when the SI joints are fused and can’t see the joint spaces

􀁸 “Injection granuloma” when see a white lucency in the SI joints (whiter than bone). Used to inject gold in the SI joints.

Butterfly vertebra

􀁸 Definition: failure of ossification of the center of the vertebra (congenital anomaly)

􀁸 Midline defect (part that never ossifies properly: Sagittal cleft defect

􀁸 If you see what appears to be a disc b/w 2 congenitally blocked vertebrae = “remnant disc” or a “rudimentary disc”

􀁸 Aka for facet tropism = asymmetrical facet

Costochondral calcification

􀁸 Benign condition

􀁸 Unknown cause, Idiopathic

􀁸 Rib cartilage calcification: anterior part of rib 8, 9 and 10 can undergo calcification

􀁸 The posterior part of the rib comes down and away from the spine. The anterior part of rib will curve back towards the spine.


􀁸 If the width of the heart shadow is wider than 1 ½ of the chest cavity 􀃆 then dealing w/ cardiomegaly

􀁸 When cardiomegaly is present it is obvious

In the lung

􀁸 If see big round white densities = Cannon ball lesions of metastatic disease

􀁸 If see small round white densities in the lungs: 3 conditions:

a. Miliary TB

b. Pulmonary TB

c. Pneumoconiosis

􀁸 To differentiate them: “Can you count them?”

a. No (too many) = Miliary TB. “Snow blizzard effect”

b. Yes = Pulmonary TB or Pneumoconiosis

􀁸 The only way to differentiate Pulmonary TB from Pneumoconiosis is by history.

􀁸 Pneumoconiosis = inhalation of dust particles (“snow storm appearance”)


􀁸 To Dx emphysema: bilateral darkening of the lung field.

􀁸 There is no such thing as a “bilateral pneumothorax”!!

􀁸 4 rad signs for emphysema:

a. Bilateral loss of the hilar (vascular) markings

b. Flattening of the diaphragm

c. Horizontal ribs (clinically see a barrel chest)

d. Compression or narrowing of the heart (= “stove-pipe heart”)

Atelectasis vs Pneumothorax

􀁸 One lung field dark, one lung field white, 2 conditions:

a. Atelectasis

b. Pneumothorax

􀁸 Atelectasis on the white or Pneumothorax on the dark side.

􀁸 Go to the dark side to differentiate them.

􀁸 If see vascular markings on the dark side 􀃆 then Dx Atelectasis

􀁸 If don’t see vascular markings on the dark side 􀃆 then Dx Pneumothorax

Hiatal Hernia

􀁸 Gastric air bubble is normally found underneath the diaphragm.

􀁸 If it is found above the diaphragm 􀃆 Dx = Hiatal hernia

􀁸 Blastic mets, lytic mets, MM never produce a periosteal rxn.


2 types

a. Congenital

b. Idiopathic

􀁸 If see a congenital anomaly on the film that is causing the curve, f.ex.: hemivertebra = congenital

􀁸 If can’t see anything = idiopathic

Structural curve vs. functional scoliotic curve

􀁸 The pt is lying prone on the table, when standing up 􀃆 curve collapses = functional


􀁸 The best way to measure a scoliosis is the Cobb method (not Risser-Ferguson)

􀁸 Always name a scoliotic curve by the convexity of the curve

􀁸 When Pt has 2 curves, measure the larger curve (the smallest is compensating)

Monitoring the scoliosis

􀁸 1-20 degrees = monitor

􀁸 20-40 degrees = no longer a chiropractic case: do not adjust, need to refer for bracing

􀁸 > 40 degrees = surgery

Complications of scoliosis

􀁸 Cardiopulmonary complications

􀁸 Postural fatigue

􀁸 Earlier degenerative changes

Clinical imaging

4 D’s of radiological interpretation

Detection: find the finding(s) on the film

1. Need a place to read films (dark room with clean view boxes and a bright light)

2. Look at the film marker/identifier

3. Search pattern: TABCS

a. Technical: 2 views at 90˚ degrees to each other is diagnostic

b. Alignment: biomechanical (big picture/postural alignment, segmental findings) and pathological (increased ADI, etc.)

c. Bone: also look at bone density

d. Cartilage: all joint spaces

e. Soft tissues: hot light for plain films, inversion for digital

4. Don’t get search satisfaction: make a finding early in the flow, and radiologist becomes satisfied and stops flowing

5. Look at all four corners of the film

Description: forensics of the film; is the finding primarily in the bone, primarily in the joint, or primarily in the soft tissues

Differential diagnosis: for the class, come up with 3

1. Surgical sieve technique

a. First one is always what you think it is

b. Second one is the twin, the legitimate possibility

c. Third is something that might look similar that might hurt the patient

2. Vindicate

a. Vascular

b. Infection

c. Neoplasm/neurologic disorders

d. Drugs/iatrogenic/degenerative causes

e. Inflammatory (arthritis)

f. Congenital

g. Autoimmune

h. Trauma

i. Endocrine/metabolic

3. When you’re in a pinch: hemorrhage, abscess, tumor (blood, pus, tumor)

Decisions: how does the information on the film impact the patient’s care

1. Is there anything I can do with plain film imaging to get to a final diagnosis? Maybe a spot view or an oblique view or compare to previous films. Special views, repeat views, comparison views, and previous views.

2. Do I have a final diagnosis on this film? Do I need advanced imaging? If so, what advanced imaging? CT to follow up chest, abdomen, acute head trauma. For everything else, MRI.

3. Is there any laboratory work that needs to be done on this patient to get a final diagnosis?

4. Do I need to refer this patient or transfer this patient to another doctor?

5. How does this impact patient care?

Basic radiographic densities


Cortical bone

Medullary bone

Water (muscle)



MRI terminology

RF: pulsed radiofrequency

Tesla: strength of magnetic field

.035 T = low field

1.0 T = high field

Spin echo pulse sequences

T1: anatomical images

fat image

fat is bright

precise anatomy

Medullary bone

Spinal cord

Low signal cortical bone

CSF intermediate

T2: pathological images

Water image

CSF is bright

Less precise detail

Normal discs bright

Subarachnoid space well seen

Myelographic effect

proton density-weighted: allow you to see tears in the fibrocartilage; needed for shoulder, hip, knee images to look for labral tears

fat saturation (STIR): sensitive to water; needed for trauma cases b/c they detect subtle edema and blood from fractures

Disc herniations

In the caudocranial direction visualized on sagittal and coronal images, we have chose the term levels.

Suprapedicle level

Pedicle level

Infrapedicle level

Disc level

M/c disc herniation is either central or posterolateral, L4-L5 herniation will affect the L5 nerve root.

If disc herniation into the foramen, L4-L5 herniation will affect the L4 nerve root. This may not cause any compression on the exiting nerve because the exiting nerve exits underneath the pedicle.

A far lateral disc herniation will almost always hit the exiting nerve root.

Ventral disc herniations affect the sympathetic chain.

A central disc herniation at L4-L5 may cause L5 symptoms, S1 symptoms, S2 symptoms, etc. b/c of the cauda equina. The L5 is tethered to the disc. Big central disc herniations cause cauda equina.