It is challenging to attempt to obtain CT perfusion (CTP) images of the hyperdense tissues, which could conceal the density of contrast material during perfusion study. We report a new technique of subtraction CTP (SCTP) to compensate the shortcomings. SCTP post-processed by perfusion software for the data of post-perfusion images subtracting pre-perfusion corresponding images slice by slice in CTP source images is technically feasible without any adverse effects on patients. It provides a new functional imaging with quantitatively hemodynamic indexes of tissue microcirculation and reflects accurately the change of blood flow in tissues and organs.