Oral Exam - Pediatrics Flashcards
Thyroid agenesis findings
No tracer activity in the expected location of the thyroid. There are no foci of activity outside of the thyroid bed to suggest ectopic tissue.
Physiologic activity within stomach and salivary glands.
Thryoid hypoplasia/agensis
– Decreased (or normal) uptake in small, abnormally
shaped eutopic gland
Dyshormonogensis
– High uptake in ± enlarged, eutopic gland
– Partial organification defect:Perchlorate test washout
10-50%
– Complete organification defect: Perchloratetest
washout > 90%
Pediatric thyroid protocol
□ Typically acquire anterior and posterior planar images with parallel hole collimator to look for thyroid tissue
□ Pinhole collimator for more detailed assessment of tissue in thyroid bed
□ Salivary gland uptake can mask subtle thyroid uptake, delayed imaging may allow washout of salivary glands
□ Can also stimulate washout of salivary glands through administration of lemon juice
Normal gastric emptying pediatrics
○ Criteria for delayed emptying are highly variable and not well established in children
– Chogle et al, 2013:Retention > 90% at 1hr, >60% a t2
hrs, >30% at 4hrs
– Rodriguezetal, 2012: ≤40% emptying at 1hr
– Half-time of > 90min for solids, >60 min for liquids
○ Liquid and solid emptying are not equivalent
– Liquid emptying may remain normal even in setting of severe gastroparesis
Gastric empyting protocol
□ Can use single head, posterior camera for young(< 8 years) and small (< 30 kg) patients
□ In young adults and larger patients, need dual head imaging with calculation of gastric emptying based on geometric mean
□ Low-energy collimator for solid emptying studies
□ Medium-energy collimator for liquid/solid dual label
studies
Meckel’s findings
Tc-99m pertechnetate scintigraphy
○ Focus of radiotracer accumulation (generally in right
lower quadrant) that (typically) appears coincident with gastric mucosa
– Generally discrete focus
– May appear ill defined if infected
– May have delayed uptake
○ Activity should not migrate/disperse (vs. activity from GI
bleed)
□ Focus of activity moves but maintains shape and
does not disperse
Meckel’s ddx
Ectopic gastric mucosa within an enteric duplication cyst - On mesenteric side of bowel
Artifact and related to physiologic gastric secretion - Can give water to see if activity clears
Artifact - renal activity
GI bleed/inflammation
Omphalomesenteric duct remnant - umbilical sinus, umbilical cyst
Biliary atresia findings
– Prompt clearance of radiotracer from blood pool
– Uniform hepatic uptake
– Non visualization of bowel on delayed imaging (24hrs)
– Patients who have developed hepatic impairment can
show delayed clearance from blood pool and
decreased hepatic uptake
Neonatal hepatitis
– Delayed clearance from blood pool
– Poor hepatic uptake
– Bowel activity often present
Ped Hepatobiliary scintigraphy protocol
□ Phenobarbital 5mg/kg/day in 2 divided doses for at least 3 and preferably 5 days prior to scan
Image acquisition
– Large field-of-view gamma camera
– 128 x 128 matrix with electronic acquisition zoom
– Low-energy all-purpose or low-energy high-resolution
collimator
– Dynamic anterior planar images
□ 1 min/frame x 60min
□ Displaying in cine mode may increase sensitivity for
subtle bowel activity
Choledochal cyst findings
- May see photopenic defect centrally on early images, which slowly accumulates tracer over time
- Large cysts can obstruct common bile duct and mimic biliary atresia
Alagille syndrome
Paucity of intrahepatic ducts
Mimics biliary atresia
Osteomyelitis/septic joint ddx
Trauma/Fracture Transient synovitis Cellulitis/soft tissue infection Legg/Calve Perthes AVN
LCP findings
– Appears initially as photopenia in proximal femoral epiphysis, characteristic pattern of revascularization/neovascularization (reappearance of uptake)
□ Stage 1A: Complete photopenia of proximal
femoral epiphysis
□ Stage 2A: Uptake in lateral column, medial
photopenia
□ Stage 3A: Anterior and medial extension of uptake
□ Stage4A: Complete revascularization
