Quantitative measurement of oxygen metabolic rate in the rat brain using microPET imaging of briefly inhaled 15O-labelled oxygen gas.
OBJECTIVE
The quantitative measurement of cerebral metabolic rate of oxygen (CMRO(2)) for rats using positron emission tomography (PET) has been technically difficult. The present study was performed to provide a technique to measure CMRO(2) for rats using a dedicated animal PET technique.


METHODS
CMRO(2) in the rat brain was quantitatively measured under alpha-chloralose anaesthesia (30 mg . kg(-1) . h(-1), intravenous infusion) using a PET imaging technique. In our experiment, the (15)O-labelled gas tracer (O(15)O) was administered by a bolus insufflation into the lung through a surgically placed cannula in the trachea. The tracer distribution was then dynamically imaged using the microPET. Unlike other conventional PET methods in which a series of arterial blood samples need to be withdrawn for the measurement of an arterial input function, no arterial blood sampling was employed. Instead, the heart was scanned in dynamic mode at the same time of imaging the brain, and the region of interest drawn over the heart was analysed to obtain an arterial input function.


RESULTS
The CMRO(2) value (micromol . 100 g(-1) . min(-1)) from 10 rats was 208 +/- 15 (mean +/- SD).


CONCLUSIONS
Our results suggest that the microPET-based CMRO(2) measurement in the rat brain combined with a non-invasive measurement of arterial input function is promising, especially for many applications involving small animals in which repeated measurements of absolute CMRO(2) need to be performed.
Yee
Seong-Hwan
SH
Research Imaging Center, University of Texas Health Science Center, San Antonio, 78229, USA. yees@uthscsa.edu
Lee
Kihak
K
Jerabek
Paul A
PA
Fox
Peter T
PT
D000280:Administration, Inhalation; D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D005740:Gases / Q000008:administration & dosage; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010104:Oxygen Radioisotopes / Q000008:administration & dosage; D049268:Positron-Emission Tomography / Q000379:methods* / Q000662:veterinary; D019275:Radiopharmaceuticals; D051381:Rats; D011916:Rats, Inbred F344
D005740:Gases; D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D010100:Oxygen