Magnetic Resonance Fingerprinting of the Pediatric Brain

Abstract

Magnetic resonance fingerprinting (MRF) is increasingly being used to evaluate brain development and differentiate normal and pathologic tissues in children. MRF can provide reliable and accurate intrinsic tissue properties, such as T1 and T2 relaxation times. MRF is a powerful tool in evaluating brain disease in pediatric population. MRF is a new quantitative MR imaging technique for rapid and simultaneous quantification of multiple tissue properties.

Keywords: Adolescent; Brain; MR imaging; Magnetic resonance fingerprinting (MRF); Pediatric; Quantitative MR imaging.

Fig. 1.

MRF data acquisition and pattern matching. Pseudorandomized acquisition parameters, including flip angles and TRs, are used in the acquisition, and each MRF image is highly undersampled and aliased. The tissue properties for each pixel are then extracted by matching the corresponding MRF signal evolution to a predefined dictionary.

Fig. 2.

Interleaved undersampling scheme in sliceencoding direction for 3D MRF (Undersampling factor, 2).

Fig. 3.

Effect of B1 field inhomogeneity. The B1 map was acquired using the Bloch-Siegert method. Corresponding T1, T2, and MWF maps obtained with and without B1 correction are shown. The difference maps were calculated using the B1-corrected maps as the reference. (Reprint from Chen et al., Neuroimage 2019)

Fig. 4.

Representative T1 and T2 maps obtained before and after k-space correction using fat navigator signal. The subject was instructed to move intentionally during the 3D MRF scan.

Fig. 5.

Schematic drawing of the CNN model with 2 modules for tissue property mapping.

Fig. 6.

T1 and T2 maps obtained from a 10-year-old female pediatric subject using submillimeter 2D MRF with residual channel attention UNet.

Fig. 7.

3D MRF (1 mm³) acquired from a 5-year-old subject in axial, coronal, and sagittal views. About 140 slices were acquired in 6 minutes, and the quantitative maps were obtained using an adult-trained CNN model.

Fig. 8.

Representative T1, T2, and MWF maps from 5 subjects at different ages. A similar slice location covering the genu and splenium of the corpus callosum was selected. Both T1 and T2 decrease, whereas MWF increases with age. (Reprint from Chen et al., Neuroimage 2019)

Fig. 9.

Representative tissue fraction segmentation maps in a patient with unilateral hippocampal sclerosis. The histogram shows the different T1 and T2 distributions between healthy and suspicious hippocampi. (Reprint from Liao et al., Radiology 2018)