Whole Body Positron Emission Tomography Attenuation Correction Map Synthesizing using 3D Deep Generative Adversarial Networks

Abstract

Background: The correction of attenuation effects in Positron Emission Tomography (PET) imaging is fundamental to obtain a correct radiotracer distribution. However direct measurement of this attenuation map is not error-free and normally results in additional ionization radiation dose to the patient. Here, we propose to obtain the whole body attenuation map using a 3D U-Net generative adversarial network. The network is trained to learn the mapping from non attenuation corrected 18-F-fluorodeoxyglucose PET images to a synthetic Computerized Tomography (sCT) and also to label the input voxel tissue. The sCT image is further refined using an adversarial training scheme to recover higher frequency details and lost structures using context information. This work is trained and tested on public available datasets, containing several PET images from different scanners with different radiotracer administration and reconstruction modalities. The network is trained with 108 samples and validated on 10 samples.Results: The sCT generation was tested on 133 samples from 8 distinct datasets. The resulting mean absolute error of the network is 103 ± 18 HU and a peak signal to noise ratio of 18.6 ± 1.5 dB. The generated images show good correlation with the unknown structural information.Conclusions: The proposed deep learning topology is capable of generating whole body attenuation maps from uncorrected PET image data. Moreover, the method accuracy holds in the presence of data form multiple sources and modalities and is trained on publicly available datasets.

The promise of artificial intelligence and deep learning in PET and SPECT imaging

“…Computer-aided tools for the analysis and processing of medical images have been developed to improve the reliability and robustness of the extracted features. Advanced machine-learning techniques are being developed to learn 1) effective similarity features, 2) a common feature representation, or 3) appearance mapping, in order to provide a model that can match large appearance variations [102,103]. Accurate organ/tumor delineation from molecular images is mainly used in the context of oncological PET imaging studies for quantitative analysis targeting various aspects, including severity scoring, radiation treatment planning, volumetric quantification, radiomic features extraction, etc.…”

Development of attenuation correction methods using deep learning in brain‐perfusion single‐photon emission computed tomography

“…In contrast, in positron emission tomography (PET), studies investigating AC using deep learning has been more widely explored. As an alternative to PET/magnetic resonance (MR) segmentation AC, studies have attempted to generate attenuation maps from MR images using deep learning 18–21 . However, because attenuation map generation requires cross‐modality transformation, one must be aware of potential pitfalls such as misalignment between subjects, field‐of‐view differences between modalities, modality‐specific artifacts, positional differences, and organ displacement during the scan 22 .…”