Abstract: Methods and systems are described for processing images. An example method may comprise receiving a plurality of images based on positron emission tomography, determining, based on the plurality of images, a plurality of calibration parameters indicative of standardized intensity values for corresponding percentiles of intensity values, determining at least one image associated with a patient. The method may comprise applying, based on the plurality of calibration parameters, a transformation to the at least one image associated with the patient. The method may comprise providing the transformed at least one image. A model may be determined based on a plurality of transformed images. The model may be used to determine an estimated disease burden of an anatomic region.