UNLABELLED: In PET, partial-volume effects cause errors in estimation of size and activity for small objects with radiopharmaceutical uptake. Recent methods for image reconstruction, compared with traditional reconstruction techniques, include algorithms for resolution recovery that result in images with higher resolution and enable quantification of size and activity of smaller objects. The purpose of this study was to evaluate a combination of 2 algorithms for volume delineation and partial-volume correction on uptake volumes smaller than 0.7 mL using image reconstruction algorithms with and without resolution recovery. METHODS: Volumes of interests (VOIs) were delineated using a threshold intensity calculated as a weighted sum of tumor and background intensities. These VOIs were used for calculating correction factors by convolving a tumor mask with the system point-spread function. The methods algorithms were evaluated using a phantom constructed from 5 small different-sized balloons filled with (18)F-FDG in background activity. Six different backgrounds were used. Data were acquired using a PET/CT scanner, and the images were reconstructed using 2 iterative algorithms, one of which used a resolution recovery algorithm. RESULTS: For the images reconstructed using the resolution recovery algorithm, the method for volume delineation resulted in VOI sizes that were correct within 1 SD for all balloons of a volume of 0.35 mL (equivalent diameter, 8.8 mm) and larger, in all backgrounds. For the images reconstructed without resolution recovery, the VOI sizes were background-dependent and generally less accurate. Correct volume delineations generally led to accurate activity estimates. CONCLUSION: The algorithms tested on the phantom developed for this study could, for this PET camera and these reconstruction algorithms, be used for accurate volume delineation and activity quantification of lesions 0.35 mL and larger.
UNLABELLED: In PET, partial-volume effects cause errors in estimation of size and activity for small objects with radiopharmaceutical uptake. Recent methods for image reconstruction, compared with traditional reconstruction techniques, include algorithms for resolution recovery that result in images with higher resolution and enable quantification of size and activity of smaller objects. The purpose of this study was to evaluate a combination of 2 algorithms for volume delineation and partial-volume correction on uptake volumes smaller than 0.7 mL using image reconstruction algorithms with and without resolution recovery. METHODS: Volumes of interests (VOIs) were delineated using a threshold intensity calculated as a weighted sum of tumor and background intensities. These VOIs were used for calculating correction factors by convolving a tumor mask with the system point-spread function. The methods algorithms were evaluated using a phantom constructed from 5 small different-sized balloons filled with (18)F-FDG in background activity. Six different backgrounds were used. Data were acquired using a PET/CT scanner, and the images were reconstructed using 2 iterative algorithms, one of which used a resolution recovery algorithm. RESULTS: For the images reconstructed using the resolution recovery algorithm, the method for volume delineation resulted in VOI sizes that were correct within 1 SD for all balloons of a volume of 0.35 mL (equivalent diameter, 8.8 mm) and larger, in all backgrounds. For the images reconstructed without resolution recovery, the VOI sizes were background-dependent and generally less accurate. Correct volume delineations generally led to accurate activity estimates. CONCLUSION: The algorithms tested on the phantom developed for this study could, for this PET camera and these reconstruction algorithms, be used for accurate volume delineation and activity quantification of lesions 0.35 mL and larger.
Authors: Lars Nyberg; Nina Karalija; Alireza Salami; Micael Andersson; Anders Wåhlin; Neda Kaboovand; Ylva Köhncke; Jan Axelsson; Anna Rieckmann; Goran Papenberg; Douglas D Garrett; Katrine Riklund; Martin Lövdén; Ulman Lindenberger; Lars Bäckman Journal: Proc Natl Acad Sci U S A Date: 2016-06-23 Impact factor: 11.205
Authors: Martin Lövdén; Nina Karalija; Micael Andersson; Anders Wåhlin; Jan Axelsson; Ylva Köhncke; Lars S Jonasson; Anna Rieckman; Goran Papenberg; Douglas D Garrett; Marc Guitart-Masip; Alireza Salami; Katrine Riklund; Lars Bäckman; Lars Nyberg; Ulman Lindenberger Journal: Cereb Cortex Date: 2018-11-01 Impact factor: 5.357
Authors: Alireza Salami; Douglas D Garrett; Anders Wåhlin; Anna Rieckmann; Goran Papenberg; Nina Karalija; Lars Jonasson; Micael Andersson; Jan Axelsson; Jarkko Johansson; Katrine Riklund; Martin Lövdén; Ulman Lindenberger; Lars Bäckman; Lars Nyberg Journal: J Neurosci Date: 2018-11-26 Impact factor: 6.167
Authors: Saana M Korkki; Goran Papenberg; Nina Karalija; Douglas D Garrett; Katrine Riklund; Martin Lövdén; Ulman Lindenberger; Lars Nyberg; Lars Bäckman Journal: Sci Rep Date: 2021-10-26 Impact factor: 4.379
Authors: Susanna Jakobson Mo; Jan Axelsson; Lars Jonasson; Anne Larsson; Mattias J Ögren; Margareta Ögren; Andrea Varrone; Linda Eriksson; David Bäckström; Sara Af Bjerkén; Jan Linder; Katrine Riklund Journal: EJNMMI Res Date: 2018-11-15 Impact factor: 3.138