Comparison of 2D simultaneous multi-slice and 3D GRASE readout schemes for pseudo-continuous arterial spin labeling of cerebral perfusion at 3 T

Objective

In this perfusion magnetic resonance imaging study, the performances of different pseudo-continuous arterial spin labeling (PCASL) sequences were compared: two-dimensional (2D) single-shot readout with simultaneous multislice (SMS), 2D single-shot echo-planar imaging (EPI) and multishot three-dimensional (3D) gradient and spin echo (GRASE) sequences combined with a background-suppression (BS) module.

Materials and methods

Whole-brain PCASL images were acquired from seven healthy volunteers. The performance of each protocol was evaluated by extracting regional cerebral blood flow (rCBF) measures using an inline morphometric segmentation prototype. Image data postprocessing and subsequent statistical analyses enabled comparisons at the regional and sub-regional levels.

Results

The main findings were as follows: (i) Mean global CBF obtained across methods was were highly correlated, and these correlations were significantly higher among the same readout sequences. (ii) Temporal signal-to-noise ratio and gray-matter-to-white-matter CBF ratio were found to be equivalent for all 2D variants but lower than those of 3D-GRASE.

Discussion

Our study demonstrates that the accelerated SMS readout can provide increased acquisition efficiency and/or a higher temporal resolution than conventional 2D and 3D readout sequences. Among all of the methods, 3D-GRASE showed the lowest variability in CBF measurements and thus highest robustness against noise.

     

Copper complex of isatin Schiff base encapsulated in zeolite as active heterogeneous catalyst: an efficient protocol for the acetylation reaction

Copper (II) complex of 3-phenylimino-1,3-dihydro-indol-2-one encapsulated in the super cages of zeolite-Y has been synthesized by flexible ligand method and characterized by various physicochemical measurements. The catalytic activity of cationic exchanged zeolite, copper complex of ligand and complex encapsulated inside the zeolite was investigated for the decomposition of H₂O₂ and for the acetylation of p-cresol. All catalysts show good to excellent yield. The results showed that conversion of p-cresol varies in the order homogeneous complex < Na-Y-Zeolite < Cu-Y-Zeolite < heterogeneous complex.