Equation-free Introduction to Post-mortem MR Image Contrast and Pulse Sequence Optimization

• NCJ Number: 251300
• Date Published: March 2016
• Author(s): N. L. Adolphi
• Agencies: NIJ-Sponsored
• Award: Investigation of the Impact of Body Temperature and Post-Mortem Interval on Magnetic Resonance Imaging (MRI) of Unfixed Tissue

Annotation

For those interested in developing a better understanding of how to optimize post-mortem magnetic resonance (PMMR) image quality, this review provides some guidance from a technical (but non-mathematical) perspective.

Abstract

Due to the excellent sensitivity of magnetic resonance (MR) imaging to subtle differences in soft tissues, MR enables non-invasive anatomical imaging with superior soft tissue contrast relative to X-ray Computed Tomography (CT); however, relative to the X-ray modalities, the utility of MR in the post-mortem setting is currently less well-defined. MR is significantly different from the X-ray modalities in terms of the underlying principles of image formation, the equipment and expertise necessary to acquire the images, and the appearance of the images themselves. Because MR is sensitive to subtle differences in soft tissues, factors unique to the post-mortem setting, particularly variations in body temperature, tend to have a greater effect on MR imaging relative to the X-ray modalities. Fortunately, MR is inherently flexible and adaptable; there are many types of MR protocols, each with user-controlled parameters that can be adjusted to achieve the best imaging of a specific pathology or anatomic structure, at a given temperature or post-mortem interval (PMI). Optimizing, validating, and standardizing post-mortem MR (PMMR) protocols is a challenging yet achievable long-term goal. A practical explanation of basic pulse sequences and MR relaxation times, and their relationship to tissue contrast, is provided in this article. Strategies for optimizing PMMR for forensic imaging applications suitable for users with varying levels of expertise are discussed in the context of current progress in this area. (Publisher abstract modified)