Automated calculation of brain parenchymal fraction as a fast and user-independent method to monitor intracranial CSF volume in hydrocephalus

Removal of a bolus of CSF by a lumbar puncture (tap test) can be used as a prognostic test in normal pressure hydrocefalus (NPH). The brain parenchymal fraction (BPF) is calculated as (intracranial volume – CSF volume) / intracranial volume. An automatic method to calculate BFP was compared with manual segmentation of lateral ventricular volume as methods to monitor changes in intracranial CSF after a tap test.