Peller M, Stehling M K, Sittek H, Kessler M, Reiser M
Department of Diagnostic Radiology, Ludwig Maximilian University, Klinikum Grosshadern, Munchen, Germany.
MAGMA. 1996 Jun;4(2):105-13. doi: 10.1007/BF01772517.
The signal modulations caused by partial volume effect and phase shift between fat and water signal in gradient-echo magnetic resonance mammography (GRE MR-mammography) have been calculated. Based on this, the theoretical sensitivity and specificity of GRE MR-mammography has been investigated considering different evaluation methods for the gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA)-based signal enhancement. The results show that both in- and out-of-phase sequences suffer from partial volume effects in voxels that contain both fat and water. This can decrease sensitivity to Gd-DTPA uptake in small, fat-embedded lesions or in pathology that contains fat interspersed histologically. Additionally, out-of-phase sequences can suffer from phase cancellation effects that can further decrease their sensitivity to Gd-DTPA uptake. In the worst case signal can actually decrease during Gd-DTPA influx. Determination of enhancement relative to the baseline value can decrease the specificity of GRE MR-mammography in the out-of-phase condition and decrease the sensitivity in the in-phase condition. These effects are less pronounced when enhancement is calculated relative to fat. These effects need to be understood since Gd-DTPA uptake is the prime indicator of malignancy in MR-mammography.
已计算出梯度回波磁共振乳腺成像（GRE MR - 乳腺成像）中由部分容积效应以及脂肪与水信号之间的相移所引起的信号调制。基于此，考虑基于钆 - 二乙烯三胺五乙酸（Gd - DTPA）的信号增强的不同评估方法，对GRE MR - 乳腺成像的理论敏感性和特异性进行了研究。结果表明，同相和反相序列在同时包含脂肪和水的体素中都会受到部分容积效应的影响。这可能会降低对小的、脂肪包埋的病变或组织学上含有散在脂肪的病理情况中Gd - DTPA摄取的敏感性。此外，反相序列可能会受到相位抵消效应的影响，这会进一步降低它们对Gd - DTPA摄取的敏感性。在最坏的情况下，在Gd - DTPA流入期间信号实际上会降低。相对于基线值确定增强会降低反相条件下GRE MR - 乳腺成像的特异性，并降低同相条件下的敏感性。当相对于脂肪计算增强时，这些影响不太明显。由于Gd - DTPA摄取是MR - 乳腺成像中恶性肿瘤的主要指标，所以需要了解这些影响。
