Influence of attenuation correction by integrated low-dose CT on somatostatin receptor SPECT

Publisher Website
Google Scholar
Abstract
Somatostatin receptor scintigraphy (SRS) is well-established in neuroendocrine tumour (NET) imaging. This study evaluated the impact of attenuation correction (AC) on SRS SPECT data in patients examined by SPECT–CT. Planar scintigraphy and SPECT–CT of 17 patients (10 men, seven women; age, 40–74 years; mean, 62 years) suffering from NET were included. For the visual assessment of AC, the intensity and contrast of foci classified as pathological were rated in both the non-attenuation corrected (NAC) and the attenuation corrected (AC) SPECT images using a 5-point score. The change in signal intensity after AC was semiquantified two-fold for each focus in both SPECTAC and SPECTNAC: firstly by using tumour-to-background (TB) ratios (defined as Tmax/Bmean) for the determination of a TBAC/TBNAC ratio. Secondly, by a Tmax,AC/Tmax,NAC ratio. Both ratios were correlated to the focus depth. A total of 46 pathological foci were found. Focus contrast and intensity significantly increased in 14/46 foci (30%) after AC (mean, 3.7–4.0) in the visual analysis (P<0.001). While TB ratios increased only in 24/46 foci after AC and no correlation between the TBAC/TBNAC ratio and focus depth (r=0.027; P=0.856) was found, Tmax was higher after AC in all foci and the Tmax,AC/Tmax,NAC ratio showed the expected correlation to focus depth (r=0.650; P<0.01), indicating the superiority of the Tmax approach for the demonstration of the effects of attenuation correction on focal uptake. Attenuation correction of SRS SPECT data by SPECT–CT results in visually more clearly contrasted foci. Moreover, as focus intensity increases, especially in the more centrally localised foci, CT-based AC has a potential to further improve the sensitivity of SRS SPECT.

This publication has 17 references indexed in Scilit: