ESR Essentials: renal imaging in children-practice recommendations by the European Society of Paediatric Radiology.

Renal pathology is common in childhood. Imaging plays a critical role in the diagnosis of kidney diseases and encompasses a range of modalities. Advanced imaging is typically performed in specialised paediatric hospitals, where experienced paediatric radiologists are familiar with the relevant techniques, protocols, indications, and limitations. However, children are often first admitted to general hospitals, where radiologists may have more limited experience in paediatric imaging. Renal cysts in children differ from those in adults, most commonly presenting as cystic kidney diseases. In the majority of cases, ultrasound (US) is the sole diagnostic modality required. Imaging is not necessary for the diagnosis of urinary tract infection (UTI), but it is essential for detecting underlying anomalies and potential complications. Urinary tract dilatation is a common finding in children; however, only up to 30% of cases require further evaluation to diagnose urinary tract obstruction or vesicourinary reflux. Urolithiasis is relatively uncommon in children and is primarily diagnosed with US, although computed tomography (CT) may occasionally be necessary. Solid renal lesions identified on US should be further evaluated in highly specialised paediatric centres. Mild to moderate renal trauma can be diagnosed and monitored using US, whereas CT remains the modality of choice for assessing severe trauma. CLINICAL RELEVANCE STATEMENT: This review provides general radiologists with a comprehensive overview of the normal renal appearance across paediatric age groups, including normal variants and imaging pathways for the most common renal pathologies in children. It also highlights scenarios where referral to specialised paediatric centres is necessary. KEY POINTS: US is the first-line imaging modality for diagnosing most renal pathologies in children. MRI is used in a variety of situations (e.g. complex congenital anomalies of the kidney and urinary tract, or focal lesions) when US is not sufficient. CT is reserved for emergencies and in selected cases of urolithiasis. Knowledge of normal renal features, including normal anatomical and morphological variants across different age groups, is essential.