Added value of material decomposition for measuring brain calcification progression with spectral computed tomography in primary familial brain calcification.

PURPOSE: To investigate the feasibility and potential added value of spectral CT-based material decomposition to quantify brain calcification progression in patients with PFBC. METHODS: First, a phantom study was performed to assess the accuracy of two dual-layer CT scanners (CT7500, IQon, Philips Healthcare) for mass measurement. Second, PFBC patients from the CALCIFACT cohort study who underwent two dual-layer CT scans between January 2022 and November 2024 were prospectively included. Calcification burden was measured with a visually graded calcification score and with volume measurements on conventional CT reconstructions. Mass measurements were performed with material decomposition using spectral data. For the volume and mass measurements a threshold of > 60 HU was applied. The significance of annual progression was tested using Wilcoxon signed-rank test. RESULTS: In the phantom study, calcification mass showed maximum median measurement errors of 2.1% and 5.0% for two scanners with a limited range in measurement errors of 0.9% for six repeated acquisitions. 25 patients (mean age, 55 years ± 17 (SD); 52% male) were included in the clinical study. Follow-up duration was 1.1 years (IQR 0.7 - 1.4). Calcification mass showed the greatest increase with an annual progression rate of 4.6% (IQR 1.1-6.5) (P < 0.001). Calcification volume (2.5% (-2.5 - 6.5) (P = 0.16)) and visual calcification score (0.0%, IQR 0.0 - 0.0, min-max 0-53.6) (P = 0.043) showed less progression. CONCLUSION: Calcification mass measurement using material decomposition is an accurate and feasible method, and may be more sensitive to calcification progression on brain CT in PFBC compared with visual scoring and volumetric quantification.