# Solid-State MRI as a Noninvasive Alternative to Computed Tomography for Craniofacial Imaging

> **NIH NIH R21** · UNIVERSITY OF PENNSYLVANIA · 2020 · $199,537

## Abstract

Abstract
 Computed tomography (CT) has been the standard imaging modality for pre- and postsurgical evaluation of
pediatric patients with craniofacial skeletal pathologies. The large difference in attenuation coefficients between
bone and soft tissue allows for straightforward segmentation, enabling creation of 3D models at high spatial reso-
lution. However, there is growing concern about potential adverse effects of repeated exposure to ionizing radia-
tion during infancy and childhood. In fact, the FDA has issued warnings cautioning against unnecessarily expos-
ing children to X-rays, stating that even though the risk is deemed relatively small, it could, nonetheless, contrib-
ute to increased risk of cancer later in life. As a result, non-radiative alternatives to CT would be particularly valu-
able to identify and manage these patients, who require multiple examinations over the course of their lifetime.
Unfortunately, conventional MR is not suited for imaging bone, which appears with near background intensity due
to very short T2 relaxation times and relatively low proton density, and thus is difficult to distinguish from air. The
premise underlying this proposal is that a new solid-state (SS) subtraction imaging technique, making use of bone
signal attenuation during and following excitation, collected in an interleaved fashion with an acquisition yielding
maximal bone signal retention, allows for superior bone-selective imaging. Along with a new k-space data sharing
approach and compressed sensing reconstruction, achieved by exploiting signal sparsity in the difference image
domain, it is hypothesized that the method will achieve high-resolution whole-skull coverage, yielding 3D render-
ings comparable to their CT analogs in less than three minutes of scan time. This hypothesis will be rigorously
evaluated in three specific Aims, starting with full implementation of image data acquisition, reconstruction and
processing (Aim 1). Subsequently, the methodology is tested in human cadaver skulls to compare its performance
based on craniometric accuracy and agreement with the gold-standard CT data. The latter is quantified in terms
of the SØrenson-Dice (SD) coefficient of the binarized 3D-rendered images, and craniometric accuracy in the form
of the concordance correlation coefficient (Aim 2). Finally, the SS-MRI method is evaluated in 30 children and ad-
olescents who are clinically indicated for craniofacial surgery guided by high-resolution CT (Aim 3). We posit that
the new method is superior to a competing gradient-echo imaging method that is unable to distinguish between
bone and background (e.g. air in the sinuses) – therefore denoted black-bone (BB) MRI. The specific hypothesis
to be tested is that the SS MRI method is more accurate than its BB counterpart with respect to the reference CT-
based renderings. Successful execution of this project should result in a clinically effective, radiation-free alterna-
tive to CT for the pre- and po...

## Key facts

- **NIH application ID:** 9899223
- **Project number:** 5R21DE028417-02
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Felix W Wehrli
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $199,537
- **Award type:** 5
- **Project period:** 2019-04-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9899223

## Citation

> US National Institutes of Health, RePORTER application 9899223, Solid-State MRI as a Noninvasive Alternative to Computed Tomography for Craniofacial Imaging (5R21DE028417-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9899223. Licensed CC0.

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