(1)H HR-MAS spectroscopy for quantitative measurement of choline concentration in amniotic fluid as a marker of fetal lung maturity: inter- and intraobserver reproducibility study.
OBJECTIVE
To determine the intra- and interobserver reproducibility of human amniotic fluid metabolite concentration measurements (including potential markers of fetal lung maturity) detectable by MR spectroscopy.


METHODS
(1)H high-resolution magic angle spinning (HR-MAS) spectroscopy was performed at 11.7 T on 23 third-trimester amniotic fluid samples. Samples were analyzed quantitatively using 3-(trimethylsilyl)propionic-2,2,3,3-d(4) acid (TSP) as a reference. Four observers independently quantified eight metabolite regions (TSP, lactate doublet and quartet, alanine, citrate, creatinine, choline, and glucose) twice from anonymized, randomized spectra using a semiautomated software program.


RESULTS
Excellent inter- and intraobserver reproducibility was found for all metabolites. Intraclass correlation as a measure of interobserver agreement for the four readers ranged from 0.654 to 0.995. A high correlation of 0.973 was seen for choline in particular, a major component of surfactant. Pearson correlation as a measure of intraobserver reproducibility ranged from 0.478 to 0.999.


CONCLUSIONS
Quantification of choline and other metabolite concentrations in amniotic fluid by high-resolution MR spectroscopy can be performed with high inter- and intraobserver reproducibility. Demonstration of reproducible metabolite concentration measurements is a critical first step in the search for biomarkers of fetal lung maturity.
Joe
Bonnie N
BN
Department of Radiology, University of California San Francisco, 1600 Divisadero St., Room C250, Box 1667, San Francisco, CA 94115, USA. Bonnie.Joe@radiology.ucsf.edu
Vahidi
Kiarash
K
Zektzer
Andrew
A
Chen
Mei-Hsiu
MH
Clifton
Matthew S
MS
Butler
Thomas
T
Keshari
Kayvan
K
Kurhanewicz
John
J
Coakley
Fergus
F
Swanson
Mark G
MG
D000293:Adolescent; D000328:Adult; D000653:Amniotic Fluid / Q000737:chemistry*; D015415:Biomarkers / Q000378:metabolism; D002794:Choline / Q000378:metabolism*; D005260:Female; D005325:Fetal Organ Maturity; D006801:Humans; D008168:Lung / Q000196:embryology*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012984:Software
D015415:Biomarkers; D002794:Choline