Abstract: Systems and methods for training end-to-end deep learning reconstruction processes, and for reconstructing medical images based on the trained deep learning processes, are disclosed. In some examples, input projection data is received. An untrained machine learning process is applied to the input projection data and, based on the application of the machine learning process to the projection data, an output image is generated. Further, a forward projection process is applied to the output image and, based on the application of the forward projection process to the output image, forward projected image data is generated. A loss value is then determined based on the forward projected image data and the input projection data. The loss value is then compared to a threshold value to determine whether the machine learning process is trained. The trained machine learning process may be employed to reconstruct images, such as positron emission tomography (PET) images.

Abstract: Systems and methods for reconstructing medical images based on the trained deep learning processes, and for training deep learning processes, are disclosed. In some examples, image measurement data is received. A histo-image is generated based on the image measurement data. Further, an attenuation map, such as a ?-map, is received. An attenuation histo-image is generated based on the attenuation map. Further, a trained machine learning process, such as a trained neural network, is applied to features generated from the histo-image and the attenuation histo-image. Based on the application of the machine learning process to the histo-image and the attenuation histo-image, output image data characterizing an image volume is generated. In some examples, a machine learning process is trained based on histo-images and corresponding attenuation histo-images. The trained machine learning process may be employed to reconstruct images, such as positron emission tomography (PET) images.

Abstract: Various systems and computer-implemented methods for Radio Frequency (RF) coil attenuation correction are disclosed. PET time-of-flight (TOF) data generated by a PET imaging modality collocated with an MR imaging modality is received. RF coil attenuation data is extracted from the PET TOF data and an initial RF coil attenuation map is generated. A trained model configured to improve a signal to noise ratio of the initial RF coil attenuation map is applied to generate a final RF coil attenuation map. Attenuation correction of the PET TOF data is performed based on the final RF coil attenuation map. An image is reconstructed from attenuation corrected PET TOF data.

Abstract: Systems and methods to estimate mean randoms include acquisition of list mode data describing true coincidences and delay coincidences detected during a scan of an object, determination of a plurality of time periods of the scan based on a distance moved by a bed supporting the object during each of the plurality of time periods, determination, for each crystal and for each of time period, of delay coincidences including the crystal based on the list mode data, determination, for each crystal, of a singles rate associated with each time period based on the delay coincidences determined for the crystal over the time period, determination, for each time period, of estimated mean randoms for each crystal pair based on the singles rate associated with the time period, and reconstruction of an image of the object based on the estimated mean randoms for each time period and the detected true coincidences.

Abstract: Systems and methods to partially-gate PET data include acquisition of first data describing a plurality of coincidences detected during a scan of an object, each of the plurality of coincidences associated with a coincidence time and a line of response, determination of lines of response which pass through a region of the object, determination of time periods of motion of the region, modification of the first data to remove coincidences which are associated with the determined lines of response and which are associated with coincidence time during the determined time periods of motion of the region, reconstruction of an image of the object based on the modified first data, and display of the image.

Abstract: Systems and methods to estimated mean randoms include acquisition of list mode data describing true coincidences and delay coincidences detected by a positron emission tomography scanner during a scan of an object, determination, for each crystal of the positron emission tomography scanner and for each of a plurality of time periods of the scan, of delay coincidences including the crystal based on the list mode data, determination, each crystal, of determine a singles rate associated with each time period based on the delay coincidences determined for the crystal over the time period, determination, for each time period, of determine estimated mean randoms for each of a plurality of pairs of the crystals based on the singles rate associated with the time period for each crystal of the crystal pair, and reconstruction of an image of the object based on the estimated mean randoms for each time period and the detected true coincidences.

Abstract: An improved method for time alignment (TA) procedure and crystal efficiency (CE) normalization estimation procedure for a PET scanner system is disclosed. In the TA procedure modeled time-of-flight (TOF) data are compared against the measured TOF data from an axially short cylinder phantom in order to find individual detector's time offsets (TOs). Then the TOs are estimated simultaneously by matching the TOF center of mass between the modeled and measured TOF data. In the CE estimation, TOF reconstruction of CBM data on the axially short cylinder phantom is performed. Alternating between TOF image reconstruction and CE updates eventually lead to the correct estimation of activity and CE component.

Abstract: Systems and methods to partially-gate PET data include acquisition of first data describing a plurality of coincidences detected during a scan of an object, each of the plurality of coincidences associated with a coincidence time and a line of response, acquisition of a motion signal associated with motion of the object during the scan, determination of lines of response which are associated with a region of the object, determination of time periods of region motion based on the motion signal, modification of the first data to remove coincidences which are associated with the determined lines of response and which are associated with a coincidence time during a time period of region motion, reconstruction of an image of the object based on the modified first data, and display of the image.

Abstract: An improved method for time alignment (TA) procedure and crystal efficiency (CE) normalization estimation procedure for a PET scanner system is disclosed. In the TA procedure modeled time-of-flight (TOF) data are compared against the measured TOF data from an axially short cylinder phantom in order to find individual detector's time offsets (TOs). Then the TOs are estimated simultaneously by matching the TOF center of mass between the modeled and measured TOF data. In the CE estimation, TOF reconstruction of CBM data on the axially short cylinder phantom is performed. Alternating between TOF image reconstruction and CE updates eventually lead to the correct estimation of activity and CE component.

Abstract: An improved method for time alignment (TA) procedure and crystal efficiency (CE) normalization estimation procedure for a PET scanner system is disclosed. In the TA procedure modeled time-of-flight (TOF) data are compared against the measured TOF data from an axially short cylinder phantom in order to find individual detector's time offsets (TOs). Then the TOs are estimated simultaneously by matching the TOF center of mass between the modeled and measured TOF data. In the CE estimation, TOF reconstruction of CBM data on the axially short cylinder phantom is performed. Alternating between TOF image reconstruction and CE updates eventually lead to the correct estimation of activity and CE component.

Abstract: Positron emission tomography (PET) with partially known attenuation accounts for the missing attenuation. Since a computed tomography (CT) scan may provide attenuation for less than all the locations used in PET reconstruction, artificial intelligence corrects for the missing attenuation. For example, the unknown attenuation or attenuation correction factors are estimated by the artificial intelligence. The known and estimated attenuations or correction factors are used in the PET reconstruction, providing more uniform PET sensitivity and better accounting for scatter. As another example, the artificial intelligence alters intensity of the activity in some locations to account for reconstruction with missing attenuation information, correcting for sensitivity variation and/or lack of scatter information for some locations.

Abstract: Systems and methods of dynamic PET imaging are disclosed. A system includes a positron emission tomography (PET) imaging modality configured to execute a first scan to acquire a first PET dataset and a processor. The first PET dataset includes dynamic PET data. The processor is configured to back-project the first PET dataset to generate a plurality of histo-image frames, input each of the plurality of histo-image frames to a trained neural network, and receive a dynamic PET output from the trained neural network. Each of the histo-image frames corresponds to a first axial position of the PET imaging modality.

Abstract: Systems and methods to estimate 3D TOF scatter include acquisition of 3D TOF data, determination of 2D TOF data from the first TOF data, determination of first estimated scatter based on the second TOF data, reconstruction of a first estimated image based on the first estimated scatter and the second TOF data, determination of attenuated unscattered true coincidences based on the first estimated image, determination of second estimated scatter based on the first TOF data and the attenuated unscattered true coincidences, and reconstruction of an image of the object based on the first TOF data and the second estimated scatter.

Abstract: A PET system for a PET/MRI machine is disclosed. The PET system includes a PET detector assembly arranged to form a single gap aligned with the high-density support structure assembly and the shielded cable assembly that run along the patient bed in the PET/MRI machine. The PET detector arrangement maximizes the allowable diameter of the PET system within the MR magnet and ensures that the high-density material does not interfere with image acquisition. Further, various image reconstruction techniques compatible with the PET detector arrangement are described.

Abstract: Various systems and computer-implemented methods for background radiation based attenuation correction are disclosed. Nuclear scan data including scan data associated with a first imaging modality and background radiation data are received. An initial background radiation attenuation map is generated and provided to a trained model configured to generate a final background radiation based attenuation map from the initial background radiation attenuation map. Attenuation correction of the scan data associated with the first imaging modality is performed based on the background radiation based attenuation map and a nuclear image is reconstructed from attenuation corrected scan data associated with the first imaging modality.

Abstract: Various systems and computer-implemented methods for background radiation based attenuation correction are disclosed. A first set of nuclear scan data including first scan data associated with a first imaging modality having a long-axial field of view and first background radiation data is received and a first background radiation attenuation map is generated by applying a trained machine-learning model to the first background radiation data. A first set of attenuation corrected scan data is generated by performing attenuation correction of the first scan data based only on the first background radiation attenuation map and a first image is reconstructed from the first set of attenuation corrected scan data. The disclosed background radiation based attenuation correction may be used for longer duration scans, repeat scans, and/or low-dose clinical applications, such as pediatric applications, theranostics, and/or other suitable applications.

Abstract: A computer-implemented method for generating a motion corrected image is provided. The method includes receiving listmode data collected by an imaging system; producing two or more histo-image frames or two or more histo-projection frames based on the listmode data; providing the two or more histo-image frames or two or more histo-projection frames to an Artificial Intelligence (AI) system; receiving two or more AI reconstructed images from the AI system based on the two or more histo-image frames or the two or more histo-projection frames; and generating a motion estimation in reconstructed images by using a motion free AI reconstructed image frame as a reference frame.

Abstract: Systems and methods to estimate 3D TOF scatter include acquisition of 3D TOF data, determination of 2D TOF data from the first TOF data, determination of first estimated scatter based on the second TOF data, reconstruction of a first estimated image based on the first estimated scatter and the second TOF data, determination of attenuated unscattered true coincidences based on the first estimated image, determination of second estimated scatter based on the first TOF data and the attenuated unscattered true coincidences, and reconstruction of an image of the object based on the first TOF data and the second estimated scatter.

Abstract: Systems and methods to estimated mean randoms include acquisition of list mode data describing true coincidences and delay coincidences detected by a positron emission tomography scanner during a scan of an object, determination, for each crystal of the positron emission tomography scanner and for each of a plurality of time periods of the scan, of delay coincidences including the crystal based on the list mode data, determination, each crystal, of determine a singles rate associated with each time period based on the delay coincidences determined for the crystal over the time period, determination, for each time period, of determine estimated mean randoms for each of a plurality of pairs of the crystals based on the singles rate associated with the time period for each crystal of the crystal pair, and reconstruction of an image of the object based on the estimated mean randoms for each time period and the detected true coincidences.

Abstract: An image reconstruction system generates a motion estimation using images that have been reconstructed using AI processing. The system receives listmode data collected by an imaging system and produces two or more histo-images based on the listmode data. The system provides the two or more histo-images to an AI system and receives two or more AI reconstructed images back from the AI system based on the two or more histo-images. The system generates a motion estimation based on the two or more AI reconstructed images.