System and method for generating attenuation map

A method of image reconstruction for positron emission tomography (PET) comprising:

• acquiring PET data indicative of a subject;
• acquiring a PET image by reconstructing the PET data, wherein the PET data is attenuation corrected by an attenuation map, wherein the attenuation map is generated by following steps:
• acquiring an MR image indicative of the subject, wherein the MR image comprises a plurality of voxels;
• fetching a reference image from a database, wherein the reference image comprises voxel segmentation information;
• registering the reference image to the MR image;
• segmenting the MR image into a plurality of regions based on the voxel segmentation information of the reference image;
• generating a first attenuation map corresponding to the MR image by assigning attenuation coefficients stored in the database to the plurality of regions of the MR image;
• for a voxel of the plurality of voxels of the MR image,
• determining a three-dimensional (3D) region in the MR image, wherein the voxel is the center of the 3D region;
• calculating a registration accuracy of the 3D region between the MR image and the reference image;
• determining a probability distribution of attenuation coefficient of the voxel based on the registration accuracy;
• updating the PET data based on the first attenuation map and generating a first PET image;
• and
• updating the first attenuation map based on the probability distribution of attenuation coefficient and the PET data of the first PET image to obtain a second attenuation map.

An imaging system comprising:

• a storage configured to store PET data of a subject and a set of instructions;
• at least one processor in communication with the storage, wherein when executing the instructions, the at least one processor is configured to cause the imaging system to:
• receive an anatomic image indicative of the subject, wherein the anatomic image comprises a plurality of voxels;
• fetch a reference image from a database, wherein the reference image comprises voxel segmentation information;
• register the reference image to the anatomic image;
• segment the anatomic image into a plurality of regions based on the voxel segmentation information;
• generate a first attenuation map corresponding to the anatomic image by assigning attenuation coefficients to the plurality of regions of the anatomic image;
• for a voxel of the plurality of voxels of the anatomic image,
• determining a three-dimensional (3D) region in the anatomic image, wherein the voxel is the center of the 3D region;
• calculate a registration accuracy of the 3D region between the anatomic image and the reference image;
• determining a probability distribution of attenuation coefficient of the voxel based on the registration accuracy;
• update the PET data based on the first attenuation map and generating a first PET image;
• update the first attenuation map based on the probability distribution of attenuation coefficient and the PET data of the first PET image to obtain a second attenuation map.