Axially varying truncation completion for MR-based attenuation correction for PET/MR

A method for truncation completion of an MR-derived attenuation image in a PET/MR system having a PET scanner with a first diameter field of view DFOVPET and an MR scanner with a second diameter field of view DFOVMR, in which a patient may be advanced through the system in sequential stations, with multiple transverse slices defined within at least one of the stations in which each slice is offset an axial distance Δz from the station centerline, comprising the steps of:

• (a) defining a center and an annulus thereabout for each slice, wherein the annulus has an inner radius Reff and an outer radius Rout extending from the center;
• (b) conducting attenuation correction of the PET scanner image data using segmented MR data from the region within the inner radius, non-attenuation corrected PET data from the region outside of the outer radius, and both non-attenuation corrected PET data and segmented MR data from the region of the annulus;
• and
• (c) decreasing Reff as a function of increasing Δz within the at least one station.

A medical imaging system through which a subject of interest may be advanced in sequential stations, comprising:

• a Positron Emission Tomography (PET) imaging system,
• a Magnetic Resonance (MR) imaging system operably coupled with said PET imaging system, and
• a computer coupled to the PET system and the MR system, said computer being programmed to:
• define multiple transverse slices within at least one of the stations in which each slice is offset an axial distance Δz from the station centerline;
• define a center and an annulus thereabout for each slice, wherein the annulus has an inner radius Reff and an outer radius Rout extending from the center;
• and
• conduct attenuation correction of image data from the PET system using MR data from the region within the inner radius, PET data from the region outside of the outer radius, and both PET and MR data from the region of the annulus, in which Reff is decreased as Δz is increased for selected slices within the at least one station.