Dept of Radiology, University Hospital of Heraklion, Medical School, University of Crete, Greece.
Eur J Radiol. 2010 Feb;73(2):305-9. doi: 10.1016/j.ejrad.2008.10.023. Epub 2008 Dec 16.
To compare two quantification techniques of apparent diffusion coefficient (ADC), both in normal liver parenchyma and focal lesions, and to investigate any potential value of normalization.
Fifty-six consecutive patients underwent MRI examination of the liver, including a single shot spin-echo echo planar imaging diffusion sequence with four b-values (0, 50, 500 and 1000s/mm(2)). ADC maps were reconstructed based on a two-point method (b-values: 500 and 1000s/mm(2)) and a four-point method (b-values: 0, 50, 500 and 1000s/mm(2)). Comparison of absolute ADC measurements of the liver, benign and malignant focal lesions was performed between the two- and four-point techniques. The same analysis was done on normalized ADC values (absolute ADC values divided by spleen ADC values).
The difference between mean two-point and four-point ADC values of normal liver (absolute: 1.237x10(-3), 1.615x10(-3)mm(2)/s, normalized: 1.40, 1.52, respectively) was statistically significant (p<0.0001 and p=0.0061). Significantly higher absolute ADC values of benign and malignant lesions were recorded with the four-point method (2.860x10(-3) and 1.307x10(-3)mm(2)/s) over the two-point method (2.243x10(-3), and 1.011x10(-3)mm(2)/s) (p<0.0001 in both) while the same differences in normalized values were proven statistically non-significant for benign lesions (p=0.788) and statistically significant for malignant lesions (p=0.015). Both differences in absolute and normalized ADC values of benign versus malignant lesions based on two- and four-point methods were found to be significant (p<0.0001).
ADC quantification of the liver may be performed with a two-point method (b-values of 500 and 1000s/mm(2)), while normalization of ADC measurements with the spleen is not further improving lesion characterization.
比较两种表观扩散系数（ADC）的量化技术，分别在正常肝实质和局灶性病变中，并探讨归一化的潜在价值。
56 例连续患者行肝脏 MRI 检查，包括单次激发自旋回波回波平面成像扩散序列，4 个 b 值（0、50、500 和 1000s/mm(2))。根据两点法（b 值：500 和 1000s/mm(2))和四点法（b 值：0、50、500 和 1000s/mm(2))重建 ADC 图。对两种技术的肝脏、良性和恶性局灶性病变的绝对 ADC 测量值进行比较。对归一化 ADC 值（绝对 ADC 值除以脾 ADC 值）进行相同的分析。
正常肝脏的两点法和四点法平均 ADC 值之间的差异具有统计学意义（绝对值：1.237x10(-3)，1.615x10(-3)mm(2)/s，归一化：1.40，1.52，分别）（p<0.0001 和 p=0.0061）。四点法记录的良性和恶性病变的绝对 ADC 值明显更高（2.860x10(-3)和 1.307x10(-3)mm(2)/s）比两点法（2.243x10(-3)和 1.011x10(-3)mm(2)/s）（p<0.0001），而良性病变的归一化值差异在统计学上无显著意义（p=0.788），恶性病变的差异有统计学意义（p=0.015）。基于两点和四点法，良性与恶性病变的绝对和归一化 ADC 值差异均具有统计学意义（p<0.0001）。
肝脏 ADC 量化可采用两点法（b 值为 500 和 1000s/mm(2))，而 ADC 测量值的脾归一化并未进一步改善病变特征。
