A Water Relaxation Atlas for Age‐ and Region‐Specific Metabolite Concentration Correction at 3 T

• Published in: NMR in biomedicine Vol. 38; no. 1; pp. e5300 - n/a
• Main Authors: Simegn, Gizeaddis Lamesgin, Song, Yulu, Murali‐Manohar, Saipavitra, Zöllner, Helge J., Davies‐Jenkins, Christopher W., Simicic, Dunja, Hupfeld, Kathleen E., Gudmundson, Aaron T., Muska, Emlyn, Carter, Emily, Hui, Steve C. N., Yedavalli, Vivek, Oeltzschner, Georg, Dean, Douglas C., Ceritoglu, Can, Ratnanather, J. Tilak, Porges, Eric, Edden, Richard
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.01.2025
• Subjects: Adult; Age; Aging; Aging - metabolism; Atlases as Topic; Brain; Brain - diagnostic imaging; Brain - metabolism; Brain mapping; brain parcels; Cerebrospinal fluid; Female; Humans; Image acquisition; Life span; Magnetic induction; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Male; metabolite quantification; Metabolites; Middle Aged; MRS; Reference signals; relaxation times; Relaxometry atlas; Substantia alba; Substantia grisea; Water; Water - chemistry; Water - metabolism; Workflow; Young Adult; Relaxometry atlas; relaxation times; aging; metabolite quantification; brain parcels; MRS
• ISSN: 0952-3480; 1099-1492; 1099-1492
• DOI: 10.1002/nbm.5300

ABSTRACT Metabolite concentration estimates from magnetic resonance spectroscopy (MRS) are typically quantified using water referencing, correcting for relaxation‐time differences between metabolites and water. One common approach is to correct the reference signal for differential relaxation within three tissue compartments (gray matter, white matter, and cerebrospinal fluid) using fixed literature values. However, water relaxation times (T1 and T2) vary between brain locations and with age. MRS studies, even those measuring metabolite levels across the lifespan, often ignore these effects, because of a lack of reference data. The purpose of this study is to develop a water relaxometry atlas and to integrate location‐ and age‐appropriate relaxation values into the MRS analysis workflow. One hundred one volunteers (51 men, 50 women; ~10 male, and 10 female participants per decade from the 20s to 60s) were recruited. T1‐weighted MPRAGE images ((1‐mm)3 isotropic resolution) were acquired. Whole‐brain water T1 and T2 measurements were made with DESPOT ((1.4 mm)3 isotropic resolution) at 3T. T1 and T2 maps were registered to the JHU MNI‐SS/EVE atlas using affine and LDDMM transformation. The atlas's 268 parcels were reduced to 130 by combining homologous parcels. Mean T1 and T2 values were calculated for each parcel in each subject. Linear models of T1 and T2 as functions of age were computed, using age − 30 as the predictor. Reference atlases of “age‐30‐intercept” and age‐slope for T1 and T2 were generated. The atlas‐based workflow was integrated into Osprey, which co‐registers MRS voxels to the atlas and calculates location‐ and age‐appropriate water relaxation parameters for quantification. The water relaxation aging atlas revealed significant regional and tissue differences in water relaxation behavior across adulthood. Using location‐ and subject‐appropriate reference values in the MRS analysis workflow removes a current methodological limitation and is expected to reduce quantification biases associated with water‐referenced tissue correction, especially for studies of aging. This study presents a water relaxometry atlas incorporating location‐ and age‐appropriate T1 and T2 values to improve MRS‐derived metabolite quantification. Using data from 101 volunteers, the atlas accounts for regional and age‐related differences in water relaxation, integrated into the Osprey MRS analysis workflow. This can help reduce quantification biases, particularly in aging studies, by correcting tissue‐specific water relaxation behavior.