Provided herein are imaging systems such as a system for quantitative tomography and a laser optoacoustic ultrasonic imaging system assembly (LOUISA) for imaging a tissue region, for example, a breast, in a subject. Generally, the system components are a laser that emits instant pulses of laser light in a wavelength cycling mode, fiberoptic bundles or optical arc-shaped fiber bundles configured to deliver laser light, an imaging module with an imaging tank, an optoacoustic array(s) of ultrawide-band ultrasonic transducers and ultrasound array(s) of ultrasonic transducers and a coupling medium and an electronics subsystem. Also provided is a method for imaging quantitative functional parameters and/or molecular parameters and anatomical structures in a volumetric tissue region of interest, such as a breast, in a subject utilizing the system for quantitative tomography.