Purpose

: Long-axial field-of-view (FOV) PET scanners have gained a lot of interest in the recent years. Such scanners provide increased sensitivity and enable unique imaging opportunities that were not previously feasible. Benefiting from the high sensitivity of a long-axial FOV PET scanner, we studied a CT-less reconstruction algorithm for the Siemens Biograph Vision Quadra with an axial FOV of 106 cm.

Methods

In this work, the background radiation from radioisotope lutetium-176 in the scintillators was used to create an initial estimate of the attenuation maps. Then, joint activity and attenuation reconstruction algorithms were used to create an improved attenuation map of the object. The final attenuation maps were then used to reconstruct quantitative PET images which were compared against CT-based PET images. The proposed method was evaluated on the data from 3 patients who underwent an FDG PET scan.

Results

Segmentation of the PET images of the 3 studied patients showed an average quantitative error of 6.5% to 8.3% across all studied organs when using attenuation maps from MLAA and 5.3% to 6.6% when using attenuation maps from MLACF.

Conclusions

Benefiting from the background radiation of lutetium-based scintillators, a quantitative CT-less PET imaging technique was evaluated in this work.

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