Detecting cervical dysplasia with QSI

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Includes bibliographical references.This thesis extends quantitative spectroscopy, a form of model-based reflectance and fluorescence spectroscopy, from a small area, contact-probe implementation to wide-area quantitative spectroscopic imaging (QSI) for complete coverage of at-risk tissue. QSI uses the scanning virtual probe concept that is critical for model-based spectroscopy and offers spatial resolution advantages over conventional wide-field illumination. We develop a QSI system capable of imaging cervical dysplasia in vivo. Using the QSI system, we conduct a clinical study to train and prospectively evaluate QSI's ability to distinguish high-grade squamous intraepithelial lesions (HSIL) from non-HSILs (less severe conditions) in cervical transformation zone. This is a clinically important distinction because HSIL requires treatment. The results show measuring the per-patient normalized reduced scattering coefficient alone accurately performs the distinction. This is in good agreement with our previous contact-probe study of HSIL. Due to improved accuracy, QSI used as an adjunct to colposcopy can potentially reduce the number of unnecessary biopsies over colposcopy alone. The results also suggest a simplified optical instrument can be used to detect HSIL and this may advance cervical dysplasia detection in developing countries, where cervical cancer mortality is highest.by Condon Lau.Ph.D