Educational Session: Pediatric Radiology Issues Maureen D. McCollough, MD, MPH, FACEP

3/24/2010 8:30 AM - 9:30 AM

Maureen McCollough MD, FACEP, FAAEM Associate Professor of Emergency Medicine and Pediatrics Keck USC School of Medicine Medical Director, Department of Emergency Medicine Los Angeles County USC Medical Center

Pediatric Radiology What you need to know Risks of Radiation 1 millirad of environmental “background” radiation received by all of us every day millirad = mrad = 1/1,000 of rad no known deleterious effects of “background’ radiation Largest additional exposure from diagnostic radiology studies Dosing by imaging study: CT scan, multidetector, head 6 rads (2-3 rads if adjusted for kids) CT scan, multidetector, abd 3 rads (1 rad if adjusted for kids) Chest xray, 2 views 10-20 millirads Abdomen xray, 1 view 50-100 millirads Biological effects of radiation: - damage to DNA but not all damage causes bad effects - single strand damage can be easily repaired - double strand damage harder to repair causes genetic mutations, carcinogenosis, cell death - some damage determined by dose radiation to eye, cataract forms in lens - some damage more insidious; any dose may cause damage; depends upon what portion of DNA is damaged; since random, no dosage is safe - carcinogenesis MOST concerning !!! - biological effects are greatest for faster-growing organisms – fetus, infant, young child; AGE AT FIRST EXPOSURE very important - most sensitive – thyroid, breast, gonad in growing children - e.g pregnant mom had xray during third-trimester fetus at 40% increased risk for particular CA so if baseline risk is 1 in 1,000 then risk rises to 1.4/1,000 - CUMULATIVE EFFECT of radiation also very important – more films, younger age, much more at risk - Cancers take awhile to develop; Young child has an entire lifetime ahead of him to develop cancer - “Brenner showed that our current CT doses overlap those doses from which excessive cancers were occurring in the atomic bomb survivors” (ref 11) - small INDIVIDUAL risk but since radiology studies are increasing exponentially then significant problem for public health - “Once the pediatric imager has SCREENED THE REQUEST FOR THE APPROPRIATENESS OF THE EXAMINATIONS ORDERED…give the least radiation necessary…; (quote from a Pediatric Radiology textbook); Emergency physicians will never accept requiring radiologists to APPROVE the appropriateness of a study - ALARA – radiation should be “as low as reasonably achievable” (ref 10) Chest Xrays Normal Chest Xray Good Film – 1. less than 1/3 of heart project below diaphragm 2. diaphragm is rounded th th th 3. 5 -6 anterior rib intersects the diaphragm (7 and above may be TOO inflated) 4. lungs are air-filled and no difference in aeration 5. medial aspects of clavicles symmetrically positioned 6. carina approximates the right pedicles (remember, trachea normally deviates to right)

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Pediatric Radiology

Expiratory Film – 1. more than 1/3 of heart projects below diaphragm 2. diaphragms are domed rather than rounded th 3. 4 anterior rib crosses diaphragm; rib 5 or 6 more ideal th 4. 9 posterior rib lies below the diaphragm 5. lungs not aerated Rotated Film – 1. Asymmetric clavicles 2. Differences in aeration between sides 3. Heart projected over one hemithorax 4. Asymmetric ribs from one side to the other Thymus – superior mediastinum is enlarged in newborn AP chest xrays due to normal large thymus; wide variety of shapes and sizes; can mimic cardiac enlargement, lobar collapse, pulmonary infiltrates, and mediastinal masses; prominent until 4-5yo but usually mostly an issue for kids 6mmin diameter, or RLQ fluid, phlegmon or abscess; Intussusception Most are idiopathic in young children and located ileocolic. Soft tissue mass in right upper quadrant – nonspecific but more common Absent liver edge sign – loss of subhepatic angle Target sign – two approximately concentric circles of fat density, due to layers of peritoneal fat surrounding and within the intussusception alternating with layers of mucosa and muscle; resembles a target or bull’s eye or doughnut appearance; seen twice as often as crescent sign Crescent sign – soft-tissue density mass of the intussusception projecting into the colon (leading edge); often has a crescent shape but may also merely resemble a protruding head into a gas-filled pocket

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Pediatric Radiology ** key to diagnosis is “air or no-air” in the ascending colon try a left-side down decubitus and prone position radiograph; if air-fluid level is identified within the distal colon, intussusception is unlikely ** ultrasound may show a mass with alternating rings of hyper- and hypo-echogenicity; on transverse plane, mass looks like a “donut”, and in longitudinal plane, resembles a “pseudokidney”; Hypertrophic Pyloric Stenosis History of vomiting in a well-appearing neonate usually leads to the diagnosis of reflux versus HPS; ultrasound is the test of choice because of ease and no radiation; normal pylorus measurements are muscle thickness median N > ulnar N; Gartland type 1 = minimally displaced and treated with closed reduction and casting (avoid flexion past 100 as may reduce blood flow); lateral condyle fractures may be small but result in significant swelling clinically 9

Pediatric Radiology Gartland type 2 = displaced with intact posterior cortex; treated with closed reduction and percutaneous fixation if long arm casting does not hold reduction; Gartland type 3 = displaced with no cortical contact ; treatment is based on degree of displacement: immobilization for 3 weeks closed reduction and percutaneous pining nd

Lateral epicondyle – 2 most common pediatric elbow fracture, 15% of all fractures Medial epicondyle – “little leaguers elbow”, 10% of all elbow injuries Nurse maid elbow – Annular ligament displacement Radial Head fracture – can be subtle; flexion and extension of the elbow may be unremarkable; abnormal fat pads may be the only sign; look for very subtle disruptions in radial head cortex; also radial head metaphysis should have very smooth contours, no corners, no right angles; should look like a tapering funnel normally; if fractured, may look more like a knob on a pole or the end of a baseball bat (handle end); avoid diagnosing elbow sprains due to likely missed very subtle radial head fracture Monteggia fracture – 1814, Monteggia described proximal ulna fracture with radial head dislocation (classic); now includes other ulna fractures; 2% of pediatric elbow fractures are Monteggia but rarely the classic; if forearm deformity exists, examine elbow and wrist; If ulna fracture seen, make sure elbow also xrayed; in kids, hyperextension of elbow causes ulna fracture with anterior angulation and anterior radial head dislocation; also hyperpronation of forearm with fall on outstretched hand (FOOSH); fracture often proximal to middle one-third of ulna; may not be complete ulnar fracture – can be a greenstick or bowing fracture with radial head displacement; annular ligament torn or displaced; posterior interosseous branch of radial nerve most often injured but is usually self-limited and resolves; innervates extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, extensor indicis; complications include recurrent radial head dislocation, persistent subluxation, limited ROM, persistent nerve injury Radial head dislocation may be associated with ulnar greenstick fracture or bowing of ulna; dislocation may be anterior, posterior or lateral ** immediate reduction of radial head dislocation needed; pediatric pts often do well with closed reduction in the OR; open reduction sometimes needed. Galeazzi fracture – fracture of distal third of radius with a dislocation of distal ulna (radioulnar dislocation); more in teenagers, adults; radioulnar dislocation may spontaneously reduce; be suspicious if there is a angled distal radius fracture; unlikely in simple distal radius Torus fratures; kids get Galeazzi-like = hyperpronation or hypersupination twisting motion causes distal radial fracture and tension on radioulnar ligaments; ligaments connecting distal ulna epiphysis to distal radius and carpal/metacarpals pull on the ulna resulting in fracture of ulna physis; Salter I or II of ulnar physis with distal radis fracture can have complications like Galeazzi; extensor digitorum communis tendon can get trapped between ulnar metaphysis and epiphysis preventing closed reduction

Development Dysplasia of the Hip (Congenital Hip Dislocation) 1 in every 1,000 births; girls > boys; left > right; instability not seen on xray (clinical finding) but persistently dislocated will be seen; hip displaced posteriorly and laterally; femoral head (not visible in young infants) not covered by acetabulum; hip ultrasound best way to make diagnosis Limp Slipped Capital Femoral Epiphysis (SCFE) - knee pain, thigh pain, groin pain, or hip pain; pain with hip internal rotation, abduction or flexion; early findings may be widening of epiphyseal line or growth plate only; soon widening and irregularity to growth plate; height of femoral head above growth plate appears shortened; eventually medial or posterior slipping of the femoral capital epiphysis; Klein’s line – line drawn up the superior border of the femoral neck should cross at least a portion of the femoral 10

Pediatric Radiology epiphysis; slip should be suspected if this straight line does NOT touch the femoral head; initial AP view may not show slip always – need true lateral; if slip is posterior, physis may appear thinner than the other side; AP view will only see inferior or medial slips; lateral views will show posterior slips; if acute slip and not walking, frog-leg view contraindicated as it may worsen slip; if chronic and walking, frog-leg indicated; most sensitive indicator is loss of lateral overhang of femoral epiphysis; DON’T MISS THIS DIAGNOSIS! Child sent home with missed SCFE may worsen slippage by continuing to walk on it lawsuit ! Often bilateral, don’t miss other side! Grade 1 - 60% slippage Avascular necrosis (AVN) of the hip - either idiopathic (Legg-Calve-Perthe’s disease) or due to another insult to the blood supply – septic arthritis, trauma especially a hip dislocation, or steroids; initially blood supply to femoral head is through small vessels in femoral head and small amount through ligamentum teres; at approx 2 yrs old, most of supply now through femoral circumflex arteries which enter the femoral head through the hip capsule; injury to hip puts blood supply at risk; typically seen in active boys; pain with hip movement and limp; pain may radiate to knee; limited internal rotation, decreased hip abduction, mild hip flexion contractures; xrays may be negative early on; if >50% femoral head involved, hip placed in abduction brace or spica cast used in young children; surgery often for older children; Avascular necrosis of the tarsal navicular (Kohler’s disease) – irregular ossification of tarsal bones is normal; if no pain, consider it normal; if painful or swollen = Kohler’s disease; boys 4-7yo; aggravated by running; xray – navicular is flattened, radiodense, and maybe fragmented; can be bilateral; short walking cast may help Avascular necrosis of the second metatarsal (Freiberg’s disease) – second metatarsal; shoe insert for ease on weight bearing th

Avascular necrosis of spine (Scheurmann’s disease) or avascular necrosis of 5 metatarsal (Ashman’s disease) Osteochondritis dessicans – small island of bone dies and then sloughs; vague pain usually knee; usually preteen or adolescence; pain with full flexion; knee may lock with flexion; possible effusion on exam; distal femur most common, seen on plain xray; immobilization with isometric exercise for quad strenghthening; possible surgery Apophysis / Apophysitis Apophysis is a growth plate that does not contribute to the overall length of the bone; calcaneal apophysis appears in boys at 8yrs old, girls 6yrs old Calcaneal apophysitis (Sever’s disease) - Achille’s tendon inserts in calcaneal apophysis; calcification of apophysis occurs at age 8 yrs in boys, 6 in girls; for 2-3 years appears irregular with possible deep clefts segmenting apophysis; repetitive trauma such as soccer, basketball, gymnastics causes microtrauma; painful heel and limp; kids age 9-12yo; tenderness at Achille’s tendon insertion, often bilateral (60%); plain xrays usually normal; xray may also show fragmentation and sclerotic changes on lateral xray (can be normal variant) BUT must also have tenderness at the Achille’s insertion; heel pads, dorsiflex exercise, discontinue sport, short leg walking cast. Tibial tuberosity apophysis (Osgood Schlatter) – insertion point for patella tendon; repetitive trauma (usually jumpers like basketball or volleyball) can cause tibial tuberosity apophysitis; often boys during growth spurts; tenderness to palpation at tibial tuberosity; pain reproduced by forced extension against resistance or jumping repetitively; in extreme injury, at risk for avulsion either 11

Pediatric Radiology partially or completely from either forced flexion when the quadriceps is contracted, or from direct trauma onto the tibial tuberosity; typical cases resolve when apophysis fuses to tibia, approx 16yo. Blount's disease – “infantile tibia vara”; major cause of angular deformation in kids; problem with growth of the posteriomedial aspect of the tibial physis excessive medial bowing of the tibia; irregularity, fragmentation, beaking of medial tibial metaphysis; physiological bowing usual until age 3 but with Blount’s disease, it becomes severe; bracing may be needed Spine Discitis – inflammation of the intervertebral disc space; most cases