Simon J H, Foster T H, Ketonen L, Totterman S, Szumowski J, Kido D K, Manzione J V, Joy S E
Department of Radiology, University of Rochester Medical Center, NY 14642.
Radiology. 1989 Sep;172(3):771-5. doi: 10.1148/radiology.172.3.771.
A decrease in the magnetic resonance (MR) imaging bandwidth can be used to increase the signal-to-noise ratio (S/N) at constant imaging time or to maintain the S/N for reduction of imaging time. The effect of bandwidth reduction from the default value of 16 kHz to 8 kHz was evaluated prospectively in 50 patients referred for MR imaging of the head. On intermediate (2,000/30 [repetition time msec/echo time msec]) and more T2-weighted (2,000/90) studies, there were no definite missed diagnoses and no diagnostically important changes in lesion characteristics when the reduced-bandwidth technique was used to obtain half- or quarter-time studies, excluding differences attributable to unintentional changes in patient position between image acquisitions. Chemical shift misregistration artifacts associated with reduced bandwidth are easily recognized with experience and do not interfere with diagnosis, as the artifacts occur in characteristic locations and diminish in most anatomic locations with increasing echo time. This study suggests the feasibility of reduced-bandwidth techniques in clinical MR imaging of the head at high field strength to achieve an increased S/N, to decrease imaging time, or to obtain images in additional projections.
在恒定成像时间下，降低磁共振（MR）成像带宽可用于提高信噪比（S/N），或者在降低成像时间的同时维持信噪比。前瞻性评估了50例因头部MR成像就诊的患者，将带宽从默认值16 kHz降低至8 kHz的效果。在中等权重（2000/30 [重复时间毫秒/回波时间毫秒]）及更多T2加权（2000/90）的检查中，当采用降低带宽技术获取一半或四分之一时间的图像时，除了图像采集期间患者位置意外变动导致的差异外，未出现明确的漏诊情况，病变特征也未出现具有诊断重要性的改变。与带宽降低相关的化学位移配准伪影凭借经验很容易识别，且不会干扰诊断，因为这些伪影出现在特定位置，并且在大多数解剖位置随着回波时间的增加而减弱。本研究表明，在高场强头部临床MR成像中，采用降低带宽技术来提高信噪比、缩短成像时间或获取额外投影的图像是可行的。
