Abstract
Background99mTc-HYNIC-TOC (Tektrotyd) is a radiopharmaceutical used for the diagnosis of lesions with overexpression of somatostatin receptors. The purpose of this study was to optimise the method and estimate normal ranges for standardized uptake values of Tektrotyd in healthy livers. MethodsAn analysis of SUVs normal ranges was performed for images acquired in a selected “healthy group” of 42 patients evaluated for NET tumours. The “pathological group” comprised 20 patients with liver lesions detected by scintigraphic imaging. Normal ranges for radiopharmaceutical uptake values were estimated based on the quantitative analysis of images acquired with a GE Healthcare NM/CT 850 gamma camera.ResultsThe method for healthy liver segmentation in SPECT/CT was optimized. The normal range of SUVs for the liver was: SUVbw max [5.2-14.0] g/ml and SUVlbm max [3.5-9.5] g/ml. The relative standard error (relative SE) of activity concentration estimated in the phantom study for the largest hot spheres was: ϕ=37mm- 5.9%, ϕ=28mm- 7.1%, ϕ=22mm- 11.4%, and ϕ=17mm- 22%.Conclusions· Segmentation in the mid-coronal CT image, at one-fourth of the height of the liver measured from the top, with a medium-sized VOI outlined on a given transverse SPECT slice was regarded as the optimal method for estimating normal ranges for standardized uptake values.· It is necessary to standardise quantification methods in the SPECT/CT studies. Our work is a step forward in obtaining standardisation of SPECT/CT SUV calculation methods.· Calculations for radiopharmaceutical uptake in tumours with volumes smaller than 5 ml are biased with a significant measurement error.
Scintigraphic imaging of small-cell lung cancer with [111In]pentetreotide, a radiolabelled somatostatin analogue
