Filippi M, Rocca M A, Gasperini C, Sormani M P, Bastianello S, Horsfield M A, Pozzilli C, Comi G
Department of Neuroscience, Scientific Institute Ospedale San Raffaele, Milan, Italy.
AJNR Am J Neuroradiol. 1999 Jan;20(1):133-7.
Different MR pulse sequences have been proposed for measuring multiple sclerosis (MS)-related abnormalities. The reproducibility of measured brain MS lesion volumes was compared for MR images performed using different scanners and different pulse sequences.
Nine patients with relapsing-remitting MS were each imaged on two scanners and, on each occasion, dual-echo conventional spin-echo, dual-echo rapid-acquisition relaxation-enhanced (RARE), and fast fluid-attenuated inversion recovery (fast-FLAIR) images were obtained. The lesion volume present on each image was evaluated three times by a single observer in random order, using a local thresholding technique.
The mean lesion volumes present on fast-FLAIR images were significantly higher than those measured on dual-echo conventional spin-echo and RARE images. The mean intraobserver coefficients of variation for the different sequences and scanners ranged from 3.0% to 4.2% (no statistically significant difference). For each of the sequences, the use of different scanners introduced a variability that was higher than the intraobserver variability: the interscanner coefficient of variation was 7.4% for conventional spin-echo, 9.5% for RARE, and 18.5% for fast-FLAIR images.
Our study confirms that the use of different scanners significantly influences lesion loads measured from MR images of patients with MS and establishes that newer sequences are more susceptible to measurement variability. It also indicates that, if newer sequences are to be used in clinical trials, careful standardization is needed.
已提出不同的磁共振（MR）脉冲序列用于测量与多发性硬化症（MS）相关的异常情况。比较了使用不同扫描仪和不同脉冲序列所获取的MR图像测量脑MS病变体积的可重复性。
9例复发缓解型MS患者分别在两台扫描仪上进行成像，每次成像时均获取双回波传统自旋回波、双回波快速采集弛豫增强（RARE）以及快速液体衰减反转恢复（fast-FLAIR）图像。由一名观察者以随机顺序使用局部阈值技术对每张图像上的病变体积进行三次评估。
fast-FLAIR图像上的平均病变体积显著高于双回波传统自旋回波和RARE图像上测量的体积。不同序列和扫描仪的观察者内变异系数均值在3.0%至4.2%之间（无统计学显著差异）。对于每个序列，使用不同的扫描仪所引入的变异性高于观察者内变异性：传统自旋回波的扫描仪间变异系数为7.4%，RARE为9.5%，fast-FLAIR图像为18.5%。
我们的研究证实，使用不同的扫描仪会显著影响从MS患者的MR图像测量的病变负荷，并确定较新的序列更容易受到测量变异性的影响。这也表明，如果要在临床试验中使用较新的序列，需要进行仔细的标准化。
