Exam 1 -- Bony Thorax (Sternum and Ribs)

bony thorax

made up of: sternum, thoracic vertebrae, lungs, 12 pairs of ribs

sternoclavical joint (SC joint)

manubrium

sternal angle

body (corpus, gladiolus) of sternum

sternum

xiphoid process

level of T9-T10

topographic landmarks

• jugular notch (T2-T3)

• sternal angle (T4-T5)

• Xiphoid tip (T9-T10)

• end of rib cage (L2-L3)

sternal rib articulations

• ribs 1 through 7 articulate with sternum

• ribs 8 through 10 articulate/merge with rib 7

rib

head of rib

neck of rib

tubercle of rib

body (shaft) of rib

true ribs

false ribs

floating ribs

costal cartilage

angle of rib

vertebral end (posterior)

costal groove of rib

for blood vessels and nerves

sternal end of rib (anterior)

posterior bony thorax articulations

synovial type with plane movement

• costotransverse joint

• costovertebral joint

costotransverse joint

• plane (gliding) motion

• diarthrodial

• between rib and transverse process

costovertebral joint

• plane (gliding) motion

• diarthrodial

• between rib and vertebral body

oblique sternum considerations

• RAO

• degree of obliquity

  • large, barrel chested thorax = 15 degrees

  • thin chested thorax = 20 degrees

technical considerations for the sternum

• breathing technique (2 to 3 seconds)

• 80 to 85 kV - digital

• short but safe SID (never use SID less than 40 inches or 100 cm)

positioning considerations for AP ribs above diaphragm

• erect if possible

• inspiration

• kV (80-85 digital)

• CR 3 to 4 inches (8 to 10 cm) below jugular notch

positioning for AP ribs below diaphragm

• recumbent

• expiration

• 80-85 kV digital

• CR midway between xiphoid process and lower ribs

overall positioning considerations for ribs

• area of interest closest to IR (AP or PA)

• axillary ribs: rotate spine away from area of interest to elongate

• marking site of injury

LPO ribs

elongates left posterior and axillary rib

RPO ribs

elongates right posterior and axillary ribs

sternum routine

RAO, lateral

sternoclavicular joint routine

PA, anterior oblique

RAO sternum

• 15 to 20 degree RAO

• CR to center of sternum (1 inch or 2.5 cm to left of midline and midway between jugular notch and xiphoid process)

• orthostatic breathing technique — 3 seconds

• trauma alternative: 15 to 20 degree cross table — angle

• AEC is not recommended

• SID > 40 inches

evaluation criteria for RAO sternum

• entire sternum visualized

• correct rotation

• optimal exposure factors

lateral sternum positioning

• CR to center of sternum

• SID — 60 to 72 inches (150 to 180cm) recommended

• suspended on inspiration

• AEC is not recommended

lateral sternum evaluation criteria

• entire sternum visualized

• no rotation

• optimal exposure factors

PA sternoclavicular joint positioning

• true PA

• CR perpendicular to T2-T3 (3 inches, or 7 cm, distal to vertebra prominens)

• suspend on expiration

evaluation criteria for PA SC joints

• medial portion of clavicles and SC joints visualized

• no rotation

• optimal exposure factors

anterior oblique positioning for SC joints

• 10 to 15 degree rotation

• CR to level of T2-T3

• 1 to 2 inches towards upside

right SC joint

RAO rotation

left SC joint

LAO rotation or a shallow RAO rotation

evaluation criteria for anterior oblique SC joints

• manubrium and medial clavicle visible

• SC joint open and shifted away from spine

• optimal exposure factors

Rib routine

basic

• AP or PA projection (area of injury closest to IR)

• unilateral or bilateral study (follow department protocol)

• axillary portion of ribs — 45 degree anterior or posterior oblique position (rotate spine away from side of interest)

option

• chest study if pulmonary injury is suspected

evaluation criteria for AP rubs above diaphragm

• first to ninth posterior ribs visualized above diaphragm

• no motion

• no rotation

• optimal exposure factors

evaluation criteria for AP ribs below diaphragm

• eighth through twelfth ribs visualized

• no motion

• no rotation

• optimal exposure factors

positioning considerations for posterior or anterior oblique upper ribs

• above diaphragm

• 45 degree oblique

• CR to T7

positioning considerations for posterior oblique below diaphragm

• can be done recumbent or erect

• 45 degree oblique

• CR midway between xiphoid process and iliac crest

evaluation criteria for oblique ribs above diaphragm

• axillary portion of ribs appear elongated

• no motion

• optimal exposure factors

rib fracture

commonly caused by trauma or underlying pathology; may cause injury to adjacent lung or cardiovascular structures (pneumothorax, pulmonary or cardiac contusion)

• fractures of first rib are often associated with injury to the underlying arteries or veins, whereas fractures to the lower ribs may be associated with injury to the spleen, liver, or kidney

flail chest

• occurs when ribs are fracture in two or more places on multiple adjacent ribs, creating a segment of ribs that are unattached to the bony thorax.

• this type of injury can lead to instability of the chest wall and create paradoxical chest movement during breathing

• is the result of severe trauma, such as blunt trauma, and is associated with underlying pulmonary injury

• if injury is suspected, perform rib studies erect if the patient’s condition permits for best visualization

sternum fractures

typically caused by blunt trauma, are associated with underlying cardiac injuries

pectus carinatum (pigeon breast)

this defect is characterized by anterior protrusion of the lower sternum and xiphoid process; it is usually a benign condition but could lead to cardiopulmonary complications in rare cases

pectus excavatum

also referred to as funnel chest, this deformity is characterized by a depressed sternum; this condition rarely interferes with respiration but often is corrected surgically for cosmetic reasons

metastases

primary malignant neoplasms spread to distant sites via blood and lymphatics; ribs are common sites for lesions, which may be characterized and visualized on the image as follows:

• osteolytic, osteoblastic, or combination osteolytic and osteoblastic

osteomyelitis

localized or generalized infection of bone and marrow can be associated with postoperative complications of open-heart surgery, which requires the sternum to be split; the most common cause of this is a bacterial infection