Prostate cancer localization by novel magnetic resonance dispersion imaging

Diagnosis and focal treatment of prostate cancer, the most prevalent form of cancer in men, is hampered by the limits of current clinical imaging. Angiogenesis imaging is a promising option for detection and localization of prostate cancer. It can be imaged by dynamic contrast-enhanced (DCE) MRI, assessing microvascular permeability as an indicator for angiogenesis. However, information on microvascular architecture changes associated with angiogenesis is not available. This paper presents a new model enabling the combined assessment of microvascular permeability and architecture. After the intravenous injection of a gadolinium-chelate bolus, time-concentration curves (TCCs) are measured by DCE-MRI at each voxel. According to the convective dispersion equation, the microvascular architecture is reflected in the dispersion coefficient. A solution of this equation is therefore proposed to represent the intravascular blood plasma compartment in the Tofts model. Fitting the resulting model to TCCs measured at each voxel leads to the simultaneous generation of a dispersion and a permeability map. Measurement of an arterial input function is no longer required. Preliminary validation was performed by spatial comparison with the histological results in seven patients referred for radical prostatectomy. Cancer localization by the obtained dispersion maps provided an area under the receiver operating characteristic curve equal to 0.91. None of the standard DCE-MRI parametric maps could outperform this result, motivating towards an extended validation of the method, also aimed at investigating other forms of cancer with pronounced angiogenic development.