Water-sensitive photoacoustic temperature characterization at 960 nm in cerebral vascular phantoms with CT co-registration.

Precise temperature monitoring is important for thermal therapy, vascular physiology, and brain function research. Photoacoustic thermometry often relies on hemoglobin-related wavelengths and is easily affected by hemoglobin concentration, oxygenation, and optical fluence. Here, we propose and validate a water-sensitive photoacoustic thermometry strategy at 960 nm in cerebrovascular phantom configurations containing a straight human whole-blood channel, with and without a bone-like shell. CT-guided registration enabled structurally constrained ROI analysis. Although frame-by-frame PAI signals fluctuated, clear temperature-dependent trends were preserved and strengthened by statistical aggregation. In the phantom without the bone-like shell, 0.1°C temperature-binned median aggregation yielded an apparent calibration R2 of 0.996 and a temperature inversion RMSE of 0.08°C; after 100-frame averaging, the noise-equivalent temperature difference decreased to 0.124°C. For the phantom with a bone-like shell, an R2 > 0.976 and an RMSE of 0.13°C were still achieved, supporting robust 960 nm photoacoustic thermometry in hemoglobin-containing cerebrovascular phantom environments.