Timely diagnosis of cerebrovascular diseases (CVD) including stroke, transient ischemic attack, reversible ischemic neurological deficit and multi-infaract dementia etc. is important for the appropriate treatment of patients. Cerebral blood flow (CBF) imaging is a routine technique used for the diagnosis of CVD. Technetium ((99m)Tc) labeled d,l-hexamethyl propylene-amineoxime ((99m)Tc-HMPAO) is widely used as a noninvasive cerebral perfusion imaging agent for the diagnosis of CVD (1). (99m)Tc-HMPAO is able to cross the blood brain barrier, is highly lipophillic and easily diffuses across the cell membrane. In the cell it is believed to be rapidly hydrolyzed into more polar hydrophilic species that are retained within the cells and can be used for imaging of the brain (1). In addition, (99m)Tc-HMPAO has also been used to label leukocytes for the detection of inflammation and infections (2, 3) and bone marrow mononuclear cells to track them under in vivo conditions (4). The synthesis and use of (99m)Tc-HMPAO is patented in the US (5) and is available commercially as a kit for intravenous use (6). The kit is approved by the United States Food and Drug Administration for the detection of altered regional cerebral perfusion in stroke or for leukocyte labeled scintigraphy as an adjunct for the localization of intra-abdominal infection and inflammatory bowel disease (IBD). .