A dual modality probe is disclosed having both a positron emission tomography sensor and a ultrasound sensor. A dual imaging system is provided having the probe and at least one external positron emission tomography detector and a data acquisition computer system for collecting data simultaneously from the positron emission sensor and the ultrasound sensor of the probe and the positron emission tomography detector. A method for evaluating a target organ of a patient utilizing the probe and imaging system, and performing a biopsy of the organ is disclosed.