Rapid method for correction of CSF partial volume in quantitative proton MR spectroscopic imaging.

Abstract

Partial volume effects with cerebrospinal fluid (CSF), if uncorrected, can lead to underestimation of metabolite concentrations in quantitative proton magnetic resonance spectroscopic imaging (MRSI) of the brain. A rapid method for the correction of CSF partial volume effects is described based on selective CSF imaging using long echo time (TE) fast spin echo (FSE) magnetic resonance imaging (MRI). In order to achieve maximum suppression of signal from brain parenchyma, the FSE sequence is coupled with an inversion recovery (IR) pulse. Scan time is minimized using single shot (SS) IR-FSE. The method is validated against a current "gold standard" for the determination of CSF volumes, namely, segmented 3D spoiled gradient-echo (SPGR) scans. Excellent agreement in CSF percentage determined by the two methods was found (linear regression analysis: slope = 0.99 +/- 0.02, intercept = 2.08 +/- 0.45; mean +/- standard errors, R = 0.93) in pooled data from four healthy subjects. An example of the use of SS-IR-FSE for partial volume correction in a leukodystrophy patient with T(2) hyperintense lesions is demonstrated. SS-IR-FSE is a simple and rapid method for applying partial volume corrections in quantitative proton MRSI, which may be of particular value in the clinical environment when time constraints do not allow longer, perhaps more accurate segmentation methods to be used.