压缩感知技术对乳腺T1高分辨率各向同性容积激发序列的成像影响及序列优化

Effect of compressed sensing on the imaging of breast T1 high resolution isotropic volume excitation sequence and its sequence optimization

目的 探讨压缩感知(compressed sense,CS)技术对乳腺T1高分辨率各向同性容积激发序列(enhanced-T1 high resolution isotropic volume excitation,e-THRIVE)图像质量及扫描时间的影响,并优化乳腺e-THRIVE序列。材料与方法 前瞻性纳入行乳腺MRI检查的43名乳腺患者(时间-信号强度曲线均为平台型),采用3.0 T MRI设备在e-THRIVE序列的基础上,采用不同加速因子(acceleration factor,AF)[敏感度编码(sensitivity encoding,SENSE)技术AF=4,CS AF=4,CS AF=5,CS AF=6,CS AF=7]对患者行乳腺MRI增强扫描。本研究在注射对比剂后的e-THRIVE序列上进行。由两位观察者对图像进行主观评价和客观测量。计算图像信噪比(signal to noise ratio,SNR)和对比噪声比(contrast to noise ratio,CNR)以及相对对比度(relative contrast,RC)。采用Friedman检验对客观评分及主观评价进行组间比较,若差异有统计学意义(P<0.05),进行后续多重比较。结果 两位观察者客观评分及主观评分一致性良好,不同AF图像间SNR腺体、CNR腺体、SNR病灶、CNR病灶及主观评分差异有统计学意义(P<0.05);不同AF图像间RC腺体-病灶、RC病灶-肌肉和RC腺体-肌肉差异无统计学意义(P>0.05)。两两比较结果表明SENSE AF=4、CS AF=4和CS AF=5图像的SNR腺体、CNR腺体、SNR病灶、CNR病灶及主观评分均大于CS AF=6和CS AF=7(P<0.05)。结论 综合考虑扫描时间和图像质量,乳腺e-THRIVE序列推荐选择AF=5的CS序列,较常规扫描并行采集缩短26.7%的扫描时间。

Objective:To investigate the impact of compressed sensing(CS)technology on breast enhanced-T1 high resolution isotropic volume excitation imaging quality and scan time,and to optimize isotropic e-THRIVE sequence.Materials and Methods:A total of 43 patients isotropic DCE-MRI examination in our hospital were prospectively included,which type of time signal intensity curve of tumor was platform type.On the basis of T1 high resolution isotropic volume excitation(e-THRIVE),different acceleration factors(AF)[sensitivity encoding(SENSE)AF=4,CS AF=4,CS AF=5,CS AF=6,CS AF=7]were used with 3.0 T MRI equipment.The sequence optimization was carried out on the delayed e-THRIVE sequence.Subjective evaluation and objective measurements of the images were performed by two observers.The image signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR)and relative contrast(RC)were calculated.Friedman test were used to analyze the SNR,CNR,RC and subjective scores of images between different groups.P<0.05 was that the difference was statistically significant,if the difference was statistically significant,follow-up multiple comparison.Results:The objective and subjective scores were consistent between the two observers,and there were significant differences in SNR_(fibroglandular),CNR_(fibroglandular),SNR_(lesion),CNR_(lesion) and subjective scores among different AF(P<0.05).There were no significant differences in RC_(fibroglandulars-to-lesion),RC_(lesion-to-muscle) and RCfibroglandulars-to-muscle among different AF(P>0.05).The results of pairwise comparison showed that SNR_(fibroglandular)s,CNR_(fibroglandular)s,SNR_(lesion),CNR_(lesion) and subjective scores of sense AF=4,CS AF=4 and CS AF=5 images were higher than those of CS AF=6 and CS AF=7 images(P<0.05).Conclusions:During clinical practice,in consideration scanning time and image quality,the CS AF=5 is recommended for breast e-THRIVE sequence,which saves 26.7%of scanning time compared with conventional parallel acquisition.