Can retrospectively fusing SPECT to CT images reduce radiation doses in myocardial perfusion imaging?

To establish if the CT dataset acquired during the stress element of myocardial perfusion imaging can be fused to the subsequent rest scan to reduce radiation doses from these procedures.

86 rest scans were processed and evaluated using a self-designed project specific tool. Recording processing time, the time between the two data sets selected for fusion and assessing radiographic reports to ensure produced images were of diagnostic quality.

70% of fused scans were acquired 6-7 days apart; the mean (SD) processing time was calculated as 2.03 (0.36) minutes. The Pearson's correlation between these two variables was determined to be 0.22, showing a slight positive correlation although not statistically significant. 100% of the images produced were of diagnostic quality.

Rest scans can be fused to a previously acquired CT, careful consideration should be given when positioning the patient and to the time interval between acquiring the two data sets, departmental guidelines can assist with this. Staff training may also be beneficial to ensure staff can assess if data sets are fusible prior to completing a scan.

This data provides evidence that retrospective fusion can reduce patient radiation doses in myocardial perfusion imaging without compromising diagnostic outcomes. Dose optimisation is an essential part of the ionising radiation (medical exposure) regulations therefore retrospective fusion should be considered in practice to ensure departmental compliance, although it is noteworthy this study is solely based in a single centred one camera department.