Assessment of paediatric craniopharyngioma progression: a comparison of contrast-enhanced and non-contrast MRI.

PURPOSE: Standard assessment of treatment response in craniopharyngioma (CP) includes volumetric measurement of solid and cystic tumour components on contrast-enhanced MRI. This study compared the detection of tumour progression using MRI with and without contrast administration. METHODS: Progressive disease (PD) was assessed based on the measurement of tumour volume change using MRI without contrast. Contrast-enhanced MRI served as the reference standard. RESULTS: In most patients, non-contrast T1- and T2-weighted sequences were sufficient to assess PD. Non-contrast MRI showed a sensitivity of 89.9%, specificity of 91.4%, positive predictive value of 0.90 (unadjusted; model-derived: 0.99), and negative predictive value of 0.90 (unadjusted; model-derived: 0.99). No improvement in the detection of PD based on CP metastatic implants along the surgical/interventional pathway was seen after contrast in our cohort. There were limitations in the detection of subtle tumour progression on non-contrast MRIs. In cases of a volume increase above the 25% threshold, particularly in the > 25-40% range, false-negative results may occur. Tumour progression with small initial volumes (≤ 0.8 cm³) may also be overlooked. CONCLUSIONS: For CPs without volume increase or no detectable or measurable tumour residue, contrast administration may be omitted. Non-contrast MRI demonstrated high diagnostic accuracy. However, performance decreased in cases with 25-40% volume increase (grey zone), where contrast-enhanced MRI is recommended, as well as for CPs with a small tumour volume (≤ 0.8 cm³). The entire skull must be evaluated to rule out CP metastatic implants; high diagnostic image quality is required.