Objective: To develop and validate a method for achieving fully quantitative single photon emission computed tomography (SPECT) data based on CT-derived corrections for attenuation, scatter and partial volume effects (PVE) in studies on patients having routine scans.

Method: The methodology used has been previously reported (1). In this validation, a clinical study was performed to assess accuracy of the quantitative technique when applied to imaging of the left ventricular blood pool. Selected patients undergoing gated heart blood pool studies (GHBPS) received an additional low dose CT scan, allowing the data to be analysed quantitatively, and gave a small peripheral venous blood sample. The calculated concentration of activity in the left ventricle was compared to the measured concentration in the whole blood sample.

Results: The average difference between the measured and true left ventricular blood concentrations in the GHBPS was 3%, with a range of (-5-+3)%.

Conclusions: This method for achieving fully quantitative SPECT is practical for clinical use, producing accurate results in patient data. It is being extended for a variety of radionuclides for diagnostic applications and is being considered for analysis of myocardial perfusion SPECT. The results for GHBPS imply similar accuracy will be achieved when quantifying myocardial perfusion imaging, offering a method for analysis of viability scores and ventricular volumes. Currently, measurement of such parameters relies on comparison to a “normal” database and is only semi-quantitative at best.


(1) K Willowson, DL Bailey and C Baldock (2008) Quantitative SPECT reconstructions using CT-derived corrections Phys Med Biol 53:3099-3112