Imaging techniques in science, engineering and medicine have evolved to expand our
ability to visualize the internal information in an object such as the human body. Examples
may include X-ray computed tomography (CT), magnetic resonance imaging (MRI),
ultrasound imaging and positron emission tomography (PET). They provide cross-sectional
images of the human body, which are solutions of corresponding inverse problems. Information embedded in such an image depends on the underlying physical principle, which is described in its forward problem. Since each imaging modality has limited viewing capability, there have been numerous research efforts to develop new techniques producing additional contrast information not available from existing methods.

There are such imaging techniques of practical significance, which can be formulated
as nonlinear inverse problems. Electrical impedance tomography (EIT), magnetic induction
tomography (MIT), diffuse optical tomography (DOT), magnetic resonance electrical
impedance tomography (MREIT), magnetic resonance electrical property tomography
(MREPT), magnetic resonance elastography (MRE), electrical source imaging and others
have been developed and adopted in application areas where new contrast information
is in demand. Unlike X-ray CT, MRI and PET, they manifest some nonlinearity, which
results in their image reconstruction processes being represented by nonlinear inverse
problems. Visualizing new contrast information on the electrical, optical and mechanical properties of materials inside an object will widen the applications of imaging methods in
medicine, biotechnology, non-destructive testing, geophysical exploration, monitoring of
industrial processes and other areas. Some are advantageous in terms of non-invasiveness, portability, convenience of use, high temporal resolution, choice of dimensional scale and total cost. Others may offer a higher spatial resolution, sacrificing some of these merits.

Owing primarily to nonlinearity and low sensitivity, in addition to the lack of sufficient
information to solve an inverse problem in general, these nonlinear inverse problems
share the technical difficulties of ill-posedness, which may result in images with a low
spatial resolution. Deep understanding of the underlying physical phenomena as well as
the implementation details of image reconstruction algorithms are prerequisites for finding
solutions with practical significance and value

Research Topics

Electrical Impedance Tomography
Magnetic Resonance EIT
Electrical Property Imaging
Magnetic Resonance Elastography
LV contours in Ultrasound
Dental CT : Metal Artifacts Reduction
Bioimpedance spectroscopy
Quantitative susceptibility mapping
Image processing
Micro EIT
Lecture Notes

Medical Imaging & Inverse Problems