University of Houston

Molecular, near-cellular and high resolution imaging modalities offer new opportunities in assessing tissue pathophysiology in situ. Since such modalities often have low tissue penetration which is often the case with optical methods, or low signal detection sensitivity, as in the case of Magnetic Resonance (MR) methods, in order to eventually translate molecular modalities into clinical practice, minimally invasive trans-cannula approaches have been introduced to position limited field-of-view (Limited-FOV) sensors locally at the area of interest. In addition, an imaging modality with a wide field-of-view (Wide-FOV) is used to guide this positioning. This work presents an approach for scanning the tissue with Limited-FOV sensors and co-registering their signals with the Wide-FOV images by means of a computer-controlled actuated manipulator. We demonstrated this approach in two stages. In the first stage using our first prototype manipulator we demonstrated the approach with two MR modalities: the proton MR spectra collected with a miniature radiofrequency (RF) coil, and the MR images acquired with a volume RF coil. In the second stage, we improved the prototype manipulator and demonstrated the manipulator-assisted multimodality loco-regional biosensing by integrating an optical sensor for light induced fluorescence (LIF) emission spectroscopy and a micro-coil for localized proton MRS.

The core of the system is scanning with the Limited-FOV sensors to collect loco-regional multimodal data (herein we will use the term 1DScans to refer those scans). We developed the abovementioned system and principles on phantoms with known boundaries that can simulate the physical and chemical structure of tissue boundaries with pathologic and non-pathologic nature. Experimental studies, with Limited-FOV modalities on multi compartment phantoms demonstrated a clear spatial separation of different biochemical profiles, in agreement with the scout-guiding MR images. With the appropriate combination of sensors, this method may allow the assessment of tissue pathophysiology in vivo. Furthermore, due to the co-registered collection of data, no computationally expensive co-registration algorithms are necessary.