In vivo visualization of displacement-distribution-derived parameters in q-space imaging

Lätt, Jimmy; Nilsson, Markus; Wirestam, Ronnie; Johansson, Edvin; Larsson, Elna-Marie; Stȧhlberg, Freddy; Brockstedt, Sara

doi:10.1016/j.mri.2007.04.001

« Previous Next »Magnetic Resonance Imaging
Volume 26, Issue 1 , Pages 77-87, January 2008

In vivo visualization of displacement-distribution-derived parameters in q-space imaging

Jimmy Lätt
- Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund University Hospital, SE-221 85 Lund, Sweden
- Corresponding author. Tel.: +46 46 178543; fax: +46 46 178540.
Markus Nilsson
- Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund University Hospital, SE-221 85 Lund, Sweden
Ronnie Wirestam
- Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund University Hospital, SE-221 85 Lund, Sweden
Edvin Johansson
- Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund University Hospital, SE-221 85 Lund, Sweden
Elna-Marie Larsson
- Department of Diagnostic Radiology, Lund University, Sweden
Freddy Stȧhlberg
- Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund University Hospital, SE-221 85 Lund, Sweden
- Department of Diagnostic Radiology, Lund University, Sweden
Sara Brockstedt
- Department of Medical Radiation Physics, Clinical Sciences, Lund University, Lund University Hospital, SE-221 85 Lund, Sweden
- Department of Diagnostic Radiology, Lund University, Sweden

Received 26 September 2006; received in revised form 5 April 2007; accepted 13 April 2007. published online 20 June 2007.

Abstract

Objective

This study aimed to explore the potential of in vivo q-space imaging in the differentiation between different cerebral water components.

Materials and Methods

Diffusion-weighted imaging was performed in six directions with 32 equally spaced q values and a maximum b value of 6600 s/mm². The shape of the signal-attenuation curve and the displacement propagator were examined and compared with a normal distribution using the kurtosis parameter. Maps displaying kurtosis, fast and slow components of the apparent diffusion coefficients, fractional anisotropy and directional diffusion were calculated. The displacement propagator was further described by the full width at half and at tenth maximum and by the probability density of zero displacement P(0). Three healthy volunteers and three patients with previously diagnosed multiple sclerosis (MS) were examined.

Results

Simulations indicated that the kurtosis of a signal-attenuation curve can determine if more than one water component is present and that care must be taken to select an appropriate threshold. It was possible to distinguish MS plaques in both signal and diffusional kurtosis maps, and in one patient, plaques of different degree of demyelinization showed different behavior.

Discussion

Our results indicate that in vivo q-space analysis is a potential tool for the assessment of different cerebral water components, and it might extend the diagnostic interpretation of data from diffusion magnetic resonance imaging.

Keywords: q space, Diffusion, MRI, Displacement distribution, Kurtosis