Influence of Temporal Sampling Rate of CTP acquisitions on Cerebral Perfusion Maps using a Digital Phantom

Purpose: To study the influence of the temporal sampling rate in cerebral CT perfusion scans using noise-free synthetic data sets created with a digital phantom. Materials and Methods: Noise-free synthetic data sets were created with a digital phantom which consists of a skull derived from a human skull phantom combined with arterial input and venous output functions, white matter (WM) and gray matter (GM) time-attenuation curves (TAC) obtained from 5 patients. By manipulating the time tags CTP protocols with a total scan duration of 60s and a temporal sampling rate of 1, 2, 3 and 4s were simulated. The 1s protocol was used as reference standard. The 2, 3 and 4s protocols were shifted with 1s to measure the influence of missing peak points of the curve, resulting in 1, 2, 3 extra data sets, respectively. CBF, CBV and MTT maps were calculated using PMA (ASIST-Japan). Mean values of GM and WM of the protocols were compared to the reference protocol. Results: By increasing temporal resolution, CBF values decreased, MTT values increased and CBV stayed relatively the same for WM and GM: CBF values were within 63%, 75% and 85% of the reference standard for 2s, 3s and 4s protocols, respectively. MTT values were within 69%, 156% and 238% of the reference standard for 2s, 3s and 4s protocols, respectively. CBV values stayed within 50% of the reference standard for all protocols. Conclusion: Cerebral perfusion values are strongly influenced by temporal sampling rate.