Abstract: Objective To explore the feasibility of reducing the number of signal averages （NSA） to shorten MRI scanning time in patients with brain tumors. Methods Imaging data from 46 patients who were suspected of brain tumors and underwent contrast-enhanced brain MRI scans at Sun Yat-sen Memorial Hospital of Sun Yat-sen University were retrospectively analyzed between March 2015 and October 2024. The number of lesions detected, signal-to-noise ratio （SNR）, contrast-to-noise ratio （CNR）, overall image quality, and subjective scores of lesion boundaries were compared between the contrast-enhanced axial T1-weighted sequences with NSA=1 and those with NSA=2 for each patient. Results The SNRs, CNRs, and overall image quality scores of the contrast-enhanced sequence with NSA=2 were 310.78± 248.05, 112.80± 151.63, and 4.74± 0.58, respectively. In contrast, those of the contrast-enhanced sequence with NSA=1 were 237.40± 159.74, 89.29± 110.18, and 4.5± 0.59, respectively. The SNRs, CNRs, and overall image quality scores of the sequence were all significantly higher than the latter （P< 0.001, P=0.002, and P=0.028, respectively）. There were no statistically significant differences in the number of lesions detected or lesion boundary scores （both were 4.67± 0.56） between the contrast-enhanced sequences with NSA=2 and those with NSA=1 （P=0.564 and P=1.000, respectively）. Conclusion Reducing NSA of the contrast-enhanced sequence from 2 to 1 significantly shortened scanning time while maintaining the samediagnostic performance. Thus, reducing NSA of the contrast-enhanced sequence from 2 to 1 to shorten the scanning time of brain tumor patients is feasible.

Key words: brain neoplasm, contrast-enhanced magnetic resonance imaging, number of signal averaged, scanning time

摘要： 目的 探讨降低信号平均次数（NSA）以缩短脑肿瘤患者对比增强MRI扫描时间的可行性。方法 回顾性分析2015年3月至2024年10月期间在中山大学孙逸仙纪念医院因临床怀疑脑肿瘤而行颅脑MRI增强扫描的46例患者的影像资料,对每例患者,比较其NSA=1和NSA=2时两个对比增强横断位T1加权序列所显示的病灶数量、信噪比（SNR）和对比噪声比（CNR）,以及两个序列的整体图像质量和病灶边界的清晰度（主观评分）。结果 NSA=2的横断位增强序列的信噪比（SNR）、对比噪声比（CNR）和整体图像质量评分分别为310.78±248.05、112.80±151.63和4.74±0.58,而NSA=1的横断位增强序列对应的值分别为237.40±159.74、89.29±110.18和4.5±0.59,统计结果显示,NSA=2序列的SNR（P<0.001）、CNR（P=0.002）和整体图像质量评分（P=0.028）均显著高于NSA=1序列。NSA=2和NSA=1时两组对比增强序列所显示的病灶数量评分（4.67±0.56 vs. 4.67±0.56,P=0.564）和病灶边界评分（4.67±0.56 vs. 4.67±0.56,P=1.000）均无统计学差异。结论 将对比增强序列的NSA由2减为1可显著缩短扫描时间,并且诊断效能并未降低。因此降低信号平均次数在脑肿瘤患者的对比增强MRI扫描中具有可行性。

关键词: 脑肿瘤, 对比增强磁共振检查, 信号平均次数, 扫描时间