Kubo's generalized cumulant expansion theorem is used to derive a theoretical expression for the nuclear magnetic resonance (NMR) signal received from a fluid moving in a time-dependent magnetic field gradient. Described in general terms by time-dependent correlation functions, this expression is used to investigate a new statistical model of microcirculation that incorporates both coherent and incoherent flow effects at the microscopic level. Based on a simple picture of the intravoxel environment, this model is developed by considering an arbitrary distribution of tortuous capillary flows. A statistical analysis of the Langevin equation describing slow tortuous capillary flow as a stochastic process reveals precisely how both coherent and incoherent flow effects contribute to the overall attenuation of the NMR spin-echo. Velocity compensated and non-compensated diffusion matched spin-echo imaging sequences are utilized to separate and quantify these respective effects noninvasively on phantoms of stationary and flowing fluid.
| Identifer | oai:union.ndltd.org:RICE/oai:scholarship.rice.edu:1911/13670 |
| Date | January 1992 |
| Creators | Minard, Kevin Roy |
| Contributors | Rorschach, Harold E. |
| Source Sets | Rice University |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 158 p., application/pdf |
Page generated in 0.0019 seconds