Image Sciences Institute/Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.
MAGMA. 2012 Feb;25(1):33-9. doi: 10.1007/s10334-011-0250-2. Epub 2011 Apr 12.
Proton resonance frequency shift (PRFS)-based MR thermometry (MRT) is hampered by heat-induced susceptibility changes when applied in tissues containing fat, e.g., the human breast. In order to assess the impact of fat susceptibility changes on PRFS-based MRT during thermal therapy in the human breast, reliable knowledge of the temperature dependence of the magnetic volume susceptibility of fat, dχ(fat)/dT, is a prerequisite. In this work we have measured dχ(fat)/dT of human breast fat tissue, using a double-reference method to ensure invariance to temperature-induced changes in the proton electron screening constant.
Ex vivo measurements were taken on a 14.1 T five mm narrow bore NMR spectrometer. Breast fat tissue samples were collected from six subjects, directly postmortem. The susceptibility was measured over a temperature range from 24°C to 65°C.
A linear behavior of the susceptibility over temperature was observed for all samples. The resulting dχ(fat)/dT of human breast fat ranged between 0.0039 and 0.0076 ppm/°C.
It is concluded that the impact of heat-induced susceptibility changes of fat during thermal therapy in the breast may not be neglected.
在包含脂肪的组织（例如人体乳房）中应用基于质子共振频率移动（PRFS）的磁共振测温（MRT）时，会受到热诱导的磁化率变化的影响。为了评估在人体乳房热疗过程中脂肪磁化率变化对基于 PRFS 的 MRT 的影响，可靠了解脂肪的磁体积磁化率随温度的变化，dχ（脂肪）/dT，是一个先决条件。在这项工作中，我们使用双参考方法测量了人体乳房脂肪组织的 dχ（脂肪）/dT，以确保不受质子电子屏蔽常数随温度变化的影响。
在 14.1 T 五毫米窄孔 NMR 光谱仪上进行了离体测量。乳房脂肪组织样本取自六位直接死后的受试者。在 24°C 至 65°C 的温度范围内测量了磁化率。
所有样本的磁化率均表现出线性温度行为。人体乳房脂肪的 dχ（脂肪）/dT 范围在 0.0039 至 0.0076 ppm/°C 之间。
可以得出结论，在乳房热疗过程中脂肪的热诱导磁化率变化的影响可能不容忽视。
