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[13] The influence of the T2 preparation pulse and fat suppression for 3D MR neurography
【Purpose】3D MR neurography with the iMSDE (improved Motion Sensitized Driven Equilibrium) pulse is a superior imaging method for depiction of nerves, such as the brachial plexus and lumber vertebrae nerve root. The T2 preparation pulse (hereinafter, referred to as BBpulse) which is a precedent pulse of iMSDE pulse controls contrast and the background signal restraint such as the muscle depending on time to apply it. We changed BBpulse and fat suppression, and investigated the influence on signal intensity and contrast.
【Methods】All images were performed using 3.0-Tesla magnetic resonance imaging (MRI) system (Ingenia 3.0T CX, Philips Medical Systems, Best, the Netherlands), and used coil was 32ch Head Coil. We made simulation samples whose T1/T2 values were similar to those of fat, cerebrospinal fluid, a skeletal muscle, nerve cells. Then we enclosed the samples in agar and imaged them. We used STIR and SPAIR as fat suppression. The parameters we changed about BBpulse were refocusing type and TEprep (iMSDE echo time). We can choose refocusing type (adiabatic or composit) and change a parameter of TEprep from 28 to 100. After that we measured the signal intensity of the simulation samples under each imaging parameters, and calculated the CNR for each simulated organization on the basis of nerve cells.
【Results】 In refocusing type, adiabatic showed a high score under almost all imaging conditions in comparison with composit in both signal intensity and CNR. In STIR, TEprep reached a peak at 30 (ms) about signal intensity and showed a peak from 30-40 (ms) about CNR. In SPAIR, as TEprep became long, signal intensity and CNR became low. On the other hand, only CNR of cerebrospinal fluid and nerve cells became high.
【Conclusion】 We were able to evaluate the influence that the T2 preparation pulse and fat suppression have on nerve depiction. It is possible that we will get the most suitable image by choosing suitable imaging parameters depending on each object. For new clinical application, we will continue to investigate this study.
【Methods】All images were performed using 3.0-Tesla magnetic resonance imaging (MRI) system (Ingenia 3.0T CX, Philips Medical Systems, Best, the Netherlands), and used coil was 32ch Head Coil. We made simulation samples whose T1/T2 values were similar to those of fat, cerebrospinal fluid, a skeletal muscle, nerve cells. Then we enclosed the samples in agar and imaged them. We used STIR and SPAIR as fat suppression. The parameters we changed about BBpulse were refocusing type and TEprep (iMSDE echo time). We can choose refocusing type (adiabatic or composit) and change a parameter of TEprep from 28 to 100. After that we measured the signal intensity of the simulation samples under each imaging parameters, and calculated the CNR for each simulated organization on the basis of nerve cells.
【Results】 In refocusing type, adiabatic showed a high score under almost all imaging conditions in comparison with composit in both signal intensity and CNR. In STIR, TEprep reached a peak at 30 (ms) about signal intensity and showed a peak from 30-40 (ms) about CNR. In SPAIR, as TEprep became long, signal intensity and CNR became low. On the other hand, only CNR of cerebrospinal fluid and nerve cells became high.
【Conclusion】 We were able to evaluate the influence that the T2 preparation pulse and fat suppression have on nerve depiction. It is possible that we will get the most suitable image by choosing suitable imaging parameters depending on each object. For new clinical application, we will continue to investigate this study.