Nuklearmedizin 2020; 59(02): 141
DOI: 10.1055/s-0040-1708285
Wissenschaftliche Poster
Medizinische Physik I
© Georg Thieme Verlag KG Stuttgart · New York

 Evaluation of tissue-dependent and spatially-variant positron-range correction for Iodine-124 PET/MR data

A Berger
1   Medical University of Vienna, QIMP Team, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
,
I Rausch
1   Medical University of Vienna, QIMP Team, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
,
D Kersting
2   University Hospital of Duisburg-Essen, Department of Nuclear Medicine, Essen, Germany
,
T Beyer
1   Medical University of Vienna, QIMP Team, Center for Medical Physics and Biomedical Engineering, Vienna, Austria
,
M Conti
3   Siemens Medical Solutions, Knoxville TN, United States
,
W Jentzen
2   University Hospital of Duisburg-Essen, Department of Nuclear Medicine, Essen, Germany
› Author Affiliations
Further Information

Publication History

Publication Date:
08 April 2020 (online)

 

Ziel/Aim Iodine-124 is increasingly being used radionuclide in positron emission tomography (PET) imaging; however, image quantification is impaired, inter alia, because of positron range (PR) effects. The aim of this study was to investigate the impact of an existing tissue-dependent and spatially-variant, image-based PR correction (PRC) in PET/MR.

Methodik/Methods The post-reconstruction PRC method used in this study is an iterative Lucy-Richardson algorithm based on a spatially-variant PR blurring kernel, valid for PET/MR, derived from an anatomical image (MR). The relative impact of PRC was evaluated using four types of imaging phantoms: (I) A soft-tissue tumor phantom that mimics tumors embedded in an environment of moderate activity concentrations, (II) a bone-lung tumor phantom that simulates hot tumors in lung and cortical bone tissue, (III) a three-tube phantom that consists of three non-radioactive tubes in a warm background to test the spill-in effects, and (IV) a resolution phantom that mimics hot capillaries in a cold background. The impact of PRC was evaluated via (i) peak-to-peak (PP) ratio analysis that describes relative changes in lesion-uptake and (ii) full width-at-half-maximum (FWHM) ratio that describes relative changes in lesion-delineation using activity line-profiles (LP) and (iii) contrast recovery analysis.

Ergebnisse/Results After correcting for PR, for lesions of diameter 19.4 mm/8.5 mm in the bone compartment of phantom II, PP ratios were 16 %/12 % higher compared to lesions in the lung compartment, showing the expected tissue-dependent PR effect. In phantom (III), cold region to warm background ratio decreased by up to 5 %, demonstrating a reduction of spill-in effects. FWHM changes of the hot compartments in phantom (IV) were 20 % and the increase in contrast recovery of phantom (I) was 13 % after PRC.

Schlussfolgerungen/Conclusions Using various phantoms, we demonstrated a noticeable effect of PR correction that requires further clinical evaluation to examine its clinical benefits.