皮下应用HSA-Gd-DTPA的磁共振淋巴造影初步研究

MR lymphography with subcutaneous administration of HSA-Gd-DTPA: an initial study in rabbits

目的初步探索皮下应用HSA-Gd-DTPA的磁共振淋巴造影的正常磁共振表现及信号强度一时间曲线。方法健康新西兰兔10只，体重2．0～2．5kg。仰卧位固定兔子，轴位和矢状位扫描双侧胭窝淋巴结。平扫序列包括T1WI、脂肪抑制T1WI和T2WI。增强扫描：平扫后双侧后肢趾蹼间隙各注射0．5ml0．20mmolGd／L的HSA-Gd-DTPA后第3、6、12、24和48h行T1WI和T1WIFS扫描。相关参数与平扫时相同。测量增强前后淋巴结的信号强度并计算淋巴结的强化率（EO），用以绘制胭窝淋巴结的信号强度-时间曲线。结果淋巴结平扫时呈T1WI等信号、T2WI高信号；增强扫描时淋巴结和淋巴管呈明显均匀强化。增强后第3小时，T1WI和T1WIFS像上胭窝淋巴结的E％分别为40．7％和42．8％，在第6小时，分别为75．60和79．7％。最大强化出现在第24小时，E％分别为215．4％和232．40A。至第48小时，胭窝淋巴结的E％仍接近1000。结论皮下间隙应用HSA-Gd-DTPA12～48h内的MR淋巴造影可清晰显示淋巴结和淋巴管，有望用于淋巴系统疾病的影像评估。

Objective To investigate preliminarily the normal appearances of MR lymphography with subcutaneous administration of HSA-Gd-DTPA and the signal intensity time course. Methods Ten healthy New-Zeanland rabbits weighted at 2.0-2.5 kg were enrolled in this study. The rabbits were in the supine position when the popliteal lymph nodes were scanned in the axial and sagittal planes. T1-weighted （TR/TE= 539/14 ms）, Tl-weighted fat suppressed （TR/TE= 539/14 ms）, and T2-weighted （TR/TE= 2234/85 ms） spin-echo （SE） images of the lymph nodes were obtained before contrast agent administration, and T1WI images were obtained 3 h, 6 h, 12 h, 24 h and 48 h after subcutaneous injection of 0.5 ml 0.20 mmol Gd/L HSA-Gd-DTPA into the interdigital skin folds of bilateral hind limb respectively. Post-contrast MR images were obtained in the same imaging planes as pre-contrast images with identical scan parameters. The signal intensities of popliteal lymph node were measured on unenhanced images and enhanced ones, and the enhancing rates（E%） were calculated to draw the signal-time course curve. Results On unenhanced images, the lymph node appeared to be iso-intensity or slight hyper-intensity on T1WI （or T1WI FS） and hyper-intensity on T2WI. On enhanced images, the lymph nodes and lymphatic vessels showed remarkable homogeneous enhancement. The E% was 40. 7% and 42. 8% at the 3rd hours, 75. 6% and 79.7% at the 6th hours on the TlWI and TlWI FS images respectively. The peak enhancement occurred at the 24th hours with the enhancing rate of 215.4% and 232.4% on TlWI and TlWI FS respectively. The enhancement effect was still remarkable at the 48th hours with the E% closed to 100%. Conclusion MR lymphography could display both lymph nodes and lymphatic vessels clearly during the 12--48 h period after subcutaneous injection of HSA-Gd-DTPA at the dose of 0.1 mmol HSA-Gd-DTPA per limb, and the technique might be applied in the imaging evaluation of lymphatic diseases.