ABR Pediatric Radiology cheat sheet

Neonatal germinal matrix hemorrhage grading: grade 1 is subependymal only; grade 2 is intraventricular without ventricular dilation; grade 3 is intraventricular with ventricular dilation; grade 4 is periventricular hemorrhagic infarction.

Term neonatal hypoxic-ischemic encephalopathy injures basal ganglia, thalamus, and parasagittal cortex; preterm injury more often produces periventricular leukomalacia.

Chiari II malformation includes myelomeningocele, small posterior fossa, inferior vermian herniation, tectal beaking, corpus callosum dysgenesis, and a fenestrated falx.

Dandy-Walker malformation consists of cystic fourth ventricular dilation, cerebellar vermian hypoplasia, and an enlarged posterior fossa with torcular-lambdoid inversion.

Supratentorial pediatric tumor locations: choroid plexus papilloma in the lateral ventricle, craniopharyngioma in the suprasellar region, and pilocytic astrocytoma as a cystic lesion with a mural nodule.

Cerebellar tumors: medulloblastoma arises in the midline vermis with restricted diffusion; ependymoma arises from the fourth ventricle floor; pilocytic astrocytoma favors the cerebellar hemisphere.

Retinoblastoma shows intraocular calcification and leukocoria; trilateral retinoblastoma includes a pineoblastoma.

Holoprosencephaly spectrum: alobar shows a single ventricle with fused thalami; semilobar shows partial separation; lobar shows nearly normal separation.

Normal neonatal thymus produces a sail sign or wave sign without tracheal displacement; it involutes with stress.

Croup causes symmetric subglottic narrowing, the steeple sign; epiglottitis causes an enlarged epiglottis, the thumb sign.

Radiolucent airway foreign body: unilateral hyperinflation may appear on inspiratory and expiratory or bilateral decubitus radiographs.

Congenital diaphragmatic hernia: left-sided bowel loops in the chest, rightward mediastinal shift, and a nasogastric tube tip above the diaphragm.

CPAM type 1 is macrocystic; type 3 is microcystic; systemic arterial supply suggests bronchopulmonary sequestration.

Tetralogy of Fallot comprises ventricular septal defect, overriding aorta, right ventricular outflow obstruction, and right ventricular hypertrophy; the heart may be boot-shaped.

D-transposition of the great arteries produces an egg-on-side heart with a narrow superior mediastinum; survival depends on mixing lesions.

Scimitar syndrome comprises right lung hypoplasia and partial anomalous pulmonary venous return to the inferior vena cava.

Hypertrophic pyloric stenosis: pyloric muscle thickness greater than 3 mm and channel length greater than 15 mm; target sign and hypochloremic metabolic alkalosis may occur.

Ileocolic intussusception shows a target or doughnut sign; air enema reduction is appropriate when the child is stable without peritonitis or pneumoperitoneum.

Malrotation: superior mesenteric artery and vein inversion on ultrasound and a corkscrew duodenal course on upper gastrointestinal contrast study.

Appendicitis: noncompressible appendix greater than 6 mm with surrounding fat stranding; an appendicolith may be present.

Biliary atresia: triangular cord sign, absent or small gallbladder, and no biliary excretion on hepatobiliary scintigraphy.

Wilms tumor is intrarenal, distorts the collecting system, and may invade the inferior vena cava; neuroblastoma is adrenal, calcifies, encases vessels, and crosses the midline.

Necrotizing enterocolitis: pneumatosis intestinalis, portal venous gas, and pneumoperitoneum in a preterm neonate.

Ovarian torsion: enlarged ovary with peripheral follicles; Doppler flow may remain normal.

Salter-Harris classification: I involves only the physis; II adds a metaphyseal fragment; III adds an epiphyseal fragment; IV involves metaphysis and epiphysis; V is a physeal crush.

Toddler fracture is a spiral tibial shaft fracture; initial radiographs may be negative and MRI can confirm the diagnosis.

Slipped capital femoral epiphysis displaces the femoral head medially and posteriorly; the ice-cream slipped off the cone sign appears on frog-leg view.

Legg-Calve-Perthes disease is idiopathic femoral head avascular necrosis in children aged four to eight; MRI detects early marrow edema and the crescent sign.

Osteosarcoma usually arises in the metaphysis with sunburst periosteal reaction and Codman triangle; chest CT is required for staging.

Ewing sarcoma favors the diaphysis with permeative bone destruction and onion-skin periosteal reaction.

Langerhans cell histiocytosis may cause vertebra plana in a child; eosinophilic granuloma is a localized form.

Achondroplasia causes rhizomelic short stature, trident hand, narrowed interpedicular distances, and foramen magnum stenosis.

Ultrasound-guided vascular access reduces arterial puncture and contrast use in pediatric interventional procedures.

Macrocystic lymphatic malformations respond best to sclerotherapy with OK-432, bleomycin, or doxycycline; microcystic lesions may require surgery or systemic therapy.

Pulmonary arteriovenous malformations, often in hereditary hemorrhagic telangiectasia, are treated with coil or plug embolization; systemic air embolization is a key risk.

Percutaneous gastrostomy uses gastropexy to fix the stomach to the abdominal wall and reduce peritoneal leakage before tract maturation.

Central venous catheter tips should lie at the cavoatrial junction; malposition increases thrombosis, arrhythmia, and extravasation risk.

Abscess drainage uses ultrasound or CT guidance with a pigtail catheter; avoid traversing bowel or pleura when an alternative window exists.

Embolization for pediatric gastrointestinal bleeding or hemoptysis uses coils or particles selected by vessel size and target.

Pediatric interventional fluoroscopy dose reduction includes pulsed fluoroscopy, collimation, and last-image hold.

Meckel diverticulum scan uses technetium-99m pertechnetate uptake by ectopic gastric mucosa; H2 blockers can improve target-to-background uptake.

Hepatobiliary scintigraphy in biliary atresia shows no biliary excretion; phenobarbital pretreatment can increase diagnostic accuracy.

Technetium-99m MAG3 diuretic renography assesses renal drainage; delayed washout after furosemide suggests obstruction.

Technetium-99m DMSA scintigraphy detects cortical renal scarring and split renal function more sensitively than ultrasound.

Direct radionuclide cystography detects vesicoureteral reflux with lower radiation dose than voiding cystourethrography.

Iodine-123 MIBG scintigraphy detects neuroblastoma and pheochromocytoma; normal liver and adrenal medulla also show uptake.

Three-phase bone scintigraphy supports osteomyelitis diagnosis; early scans may be normal.

FDG PET is useful for pediatric lymphoma and sarcoma staging; normal high brain uptake limits central nervous system evaluation.

Pediatric CT protocols adjust tube current and peak kilovoltage by patient size and use iterative reconstruction to lower dose.

Fluoroscopy dose reduction tools include pulsed fluoroscopy, collimation, last-image hold, and removal of the grid when appropriate.

Approximate effective doses: chest radiograph 0.1 mSv; abdominal CT 5 to 10 mSv; average background radiation 3 mSv per year.

Children have greater lifetime radiation risk because of longer life expectancy and higher sensitivity of thyroid, breast, and bone marrow.

Gonadal shielding is used when it does not obscure the diagnostic area; routine shielding is not universal for all examinations.

CT dose-length product equals CTDIvol multiplied by scan length; effective dose is estimated by multiplying dose-length product by a body-region conversion factor.

ALARA principles for staff use time, distance, and shielding; radiation intensity follows the inverse square law.

Pregnancy status is checked before pelvic imaging; lead apron shielding and dose estimation guide fetal risk assessment.