In perfusion MR imaging, the term ‘perfusion’ comprises several tissue hemodynamic parameters (cerebral blood volume – CBV, cerebral blood flow – CBF, and mean transit time - MTT) that can be derived from the acquired data. In the evaluation of intracranial mass lesions, however, CBV appears to be the most useful parameter.
There are three techniques in wide use to derive one or more perfusion values:
time to peak (TTP)
mean transit time (MTT)
cerebral blood volume (CBV)
cerebral blood flow (CBF)
negative enhancement integral (NEI)
The main role of perfusion imaging is in evaluation of ischaemic conditions (e.g. acute cerebral infarction to determine ischaemic penumbra, moya-moya disease to identify vascular reserve) and neoplasms (e.g. identify highest grade component of diffuse astrocytomas, help distinguish glioblastomas form cerebral metastases).