OBJECTIVES: During the development of new diagnostic and therapeutic devices, it is desirable to indicate their cost-effectiveness and to establish their potential clinical value to guide further research. In these early stages of development, however, there are usually limited or no clinical data available. In this study, expert elicitation was used to estimate uncertain priors of the diagnostic performance of a new imaging technology, i.e. Photo Acoustic Mammography (PAM). We compared PAM to Magnetic Resonance Imaging (MRI), in the detection of breast cancer.   METHODS: Expert elicitation was used as a method to formulate the knowledge and beliefs of experts about the future performance of PAM and to quantify this information into probability distributions. 18 radiologists estimated the true positive rate and true negative rate based on existing MRI data and specified the mode, the lower, and the upper boundaries (95% credible interval). An overall probability density function (PDF) was determined using the linear opinion pooling method in which weighting is applied to reflect the performance of individual experts. RESULTS: The overall PDF indicated a sensitivity ranging from 58.9% to 85.1%, with a mode of 73.3%. The specificity ranges from 52.2% to 77.6%, with a mode of 66.5%. Experts expressed difficulties making the estimations, as there is not sufficient data about the manner in which PAM visualizes different tumor types.   CONCLUSIONS: Using expert elicitation prior distributions for sensitivity and specificity of PAM were obtained. This evidence could be used in early health economic models to establish cost-effectiveness. However, experts expressed difficulties estimating the performance based on limited data. The expression of uncertainty surrounding their beliefs reflects the infancy of the diagnostic method, however further clinical trials should be commissioned to indicate whether these results are valid. Before that, the use of the elicited priors in health economic models requires careful consideration.