Leptomeningeal Vascularity in Gadopiclenol-Enhanced Pediatric Brain MRI

Gadolinium-based contrast agents (GBCAs) are essential in pediatric neuroimaging, enabling visualization of pathology that disrupts the blood-brain barrier. Gadopiclenol is a new macrocyclic GBCA with higher T1 relaxivity, permitting a 50% dose reduction while maintaining diagnostic quality. However, it is unknown whether this higher relaxivity alters background extra-axial vascular enhancement. We hypothesized that gadopiclenol, despite its lower dose, would increase background enhancement on postcontrast pediatric brain MRI compared with gadoterate meglumine (Gd-DOTA).

In this retrospective observational study, 302 contrast-enhanced brain MRI studies in patients aged 2-18 years were reviewed: 151 with gadopiclenol (0.05 mmol/kg) and 151 with Gd-DOTA (0.1 mmol/kg). Postcontrast sequences included 3D T1 spin-echo (SE), 3D T1 spoiled gradient-echo (SPGR), 2D T1 TSE, and 2D FLAIR. Two neuroradiologists established binary enhancement categories based on sulcal enhancement thresholds (high versus low). One reader assigned scores for all studies; a second reader evaluated a subset for interobserver agreement. Logistic regression assessed the association between contrast agent and high enhancement, adjusting for age, sex, anesthesia, and scanner field strength.

Gadopiclenol was independently associated with significantly greater odds of high extra-axial enhancement on all T1-weighted sequences: 3D T1 SE (OR = 10.2; P < .001), 3D T1 SPGR (OR = 10.7; P < .001), and 2D T1 TSE (OR = 14.0; P < .001). Anesthesia was also an independent predictor of high enhancement on 3D SE and SPGR. On 2D FLAIR, contrast agent had no effect; instead, younger age was associated with high enhancement (P = .022), with an age-anesthesia interaction suggesting attenuation of this effect under sedation. Interobserver agreement was moderate to substantial (κ = 0.530-0.632).

Gadopiclenol increases background extra-axial enhancement on T1-weighted postcontrast sequences in pediatric brain MRI, likely reflecting its higher relaxivity. Radiologists should be aware of this effect to avoid misinterpretation as leptomeningeal pathology. Postcontrast FLAIR remains unaffected and continues to serve as a reliable sequence for detecting true meningeal disease.