Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

String Theory Applied to Magnetic Resonance Imaging and Guitars

Jerry Battista

Friday, March 23, 2012
1:30 PM @ Stirling A

Abstract:

Magnetic Resonance Imaging (MRI) is used routinely in diagnostic medicine because of excellent soft-tissue contrast and avoidance of radiation risk to the patient. The image data acquisition sequence can be programmed to yield a multi-parametric map of pixels that accentuate the proton density, spin relaxation times (T1, T2), or other chemical properties of the tissue. The versatility of MRI is an obvious advantage over purely densitometric x-ray imaging, but it also complicates the teaching of this flexible imaging method to a wide range of students in Physics or Medicine. The concepts of magnetic resonance imaging are most often introduced using nuclear spin with a confusing underlay of quantum mechanics. While this "first principles" approach appear to be more rigorous, it leaves many students dazzled by a complexity that is generally not necessary for understanding the basic imaging principles. In this lecture, the data acquisition and image reconstruction schemes used in MRI are explained through analogy with music and the guitar instrument. Wave theory forms the bridge to concepts of resonance, harmonics, damped oscillations, and frequency encoding. Fourier analysis is the final tool that enables image reconstruction based on "listening to" encoded radiofrequency signals. This lecture should prove interesting and informative to medical physics students and educators alike.