Pediatric Interventional Radiology
Pediatric interventional radiology emphasizes minimally invasive therapy with attention to small patient size, sedation, and radiation dose. Common procedures include image-guided central venous access (PICC and tunneled catheters), gastrostomy and gastrojejunostomy tube placement, abscess and fluid drainage, biopsy, sclerotherapy of lymphatic and venous malformations, embolization for trauma or gastrointestinal bleeding, and foreign body retrieval. Intussusception reduction is a classic fluoroscopic procedure; it is contraindicated when there is perforation, peritonitis, or shock. Abscess drainage in children can often replace surgery; choose the smallest catheter that will drain the collection and use ultrasound guidance when possible.
Understand malformation management: infantile hemangiomas often respond to propranolol and are rarely embolized unless complicated; lymphatic malformations are treated with sclerosing agents such as OK-432 or bleomycin; venous malformations are treated with foam sclerotherapy. Know the preprocedural checklist: fasting status, coagulation, renal function, allergies, antibiotics, and anesthesia plan. Traps include using adult-sized equipment, underestimating blood loss in a small child, and failing to limit fluoroscopy time. Contrast volume should be weight-based, and carbon dioxide angiography is rarely used in small children.
Worked rule: Before draining a cystic lesion, confirm it is not an echinococcal cyst or a vascular malformation; aspirating a vascular lesion can cause serious bleeding.
Nuclear Medicine
Pediatric nuclear medicine differs from adult practice mainly in radiopharmaceutical dosing, patient preparation, and image interpretation. Doses are weight-based, often using a pediatric dose card or a validated pediatric dosage scheme; never scale an adult dose linearly. Common studies include renal cortical scintigraphy with dimercaptosuccinic acid for scarring, diuretic renography with mercaptoacetyltriglycine for obstruction, radionuclide cystography for reflux, hepatobiliary scintigraphy for biliary atresia, Meckel diverticulum scanning with pertechnetate, bone scanning, metaiodobenzylguanidine imaging for neuroblastoma, and PET/CT. Sedation and immobilization must be planned, and hydration and bladder emptying are important for renal studies.
Traps are frequent. A Meckel scan can be false-negative if the child has recently received barium or antacids, and false-positive uptake can occur in other ectopic gastric mucosa or bowel inflammation. Hepatobiliary scintigraphy in biliary atresia shows no gallbladder filling and no intestinal activity, but the scan may be equivocal in neonatal hepatitis. Diuretic renography must be interpreted with the diuretic timing and bladder status. Bone scans in children show physiologic uptake at growth plates, which should not be called metastatic disease. Always review prior imaging and correlate with ultrasound or MRI.
Worked rule: For a suspected Meckel diverticulum, pretreat with an H2 receptor blocker and image dynamically; a focal area of pertechnetate uptake in the right lower quadrant that appears with the stomach is characteristic.
Radiation Safety
Radiation safety is a core competency in pediatric imaging because children have greater radiosensitivity and a longer lifetime to express radiation-induced cancer. The guiding principles are justification and optimization: every examination must have a clinical indication, and the dose must be as low as reasonably achievable. Use ultrasound or MRI when they can answer the question. In CT, adjust kVp and mAs to patient size, use iterative reconstruction, limit the scan range, and avoid multiphase studies. In fluoroscopy, use pulsed fluoroscopy, last-image hold, tight collimation, and the lowest magnification; record fluoroscopy time and dose. The Image Gently campaign provides practical checklists. Dose descriptors include CTDIvol, dose-length product, and size-specific dose estimates; effective dose allows comparison but is not a patient-specific risk.
Traps include assuming that a brighter image is better, repeating a study because of poor positioning, and using adult protocols on small children. Gonadal shielding is no longer routine for all examinations and may obscure anatomy; follow current institutional policy. Pregnancy screening and communication with parents are essential. Sedation should be optimized so that motion does not force repeats. Keep a record of prior imaging to avoid duplication.
Worked rule: Before ordering a pediatric CT, ask whether the result will change management; if not, the correct action is to omit the study. If CT is necessary, use a child-specific protocol and limit the field to the region of interest.