Extending Decades-Old Chemistry and Physics to Improve Modern Molecular Imaging Seminar

Molecular imaging-the use of chemical signatures to image function instead of merely structure-promises to enable a new generation of clinical modalities that can revolutionize both diagnosis and treatment. I will focus on two specific modalities-magnetic resonance and optical imaging-and discuss how a close coupling between basic physics on the one hand, and focused clinical questions on the other hand, enable new and important applications. For example, in magnetic resonance, it has been known since the 1950s that chemically equivalent spins (related by symmetry) can still give very complex spectra unless they are also magnetically equivalent; today we use this to create hyperpolarized molecular agents which take many minutes to return to equilibrium (hundreds of times longer than conventional magnetization), and this dramatically increases the molecular information that can be obtained in imaging. In optics, our lab has developed advanced femtosecond pulse shaping and detection technologies to access intrinsic nonlinear signatures that were not previously observable in tissue such as excited state absorption, ground state depletion, cross phase modulation. Applications to imaging hemoglobins and melanins in tissue will be highlighted, including recent work which could revolutionize melanoma diagnosis by improving the pathology “gold standard”. I will also present work on nonlinear imaging of historical pigments in Renaissance paintings to infer the artist’s original colors and intent.