Interstitial Magnetic Resonance Lymphography with Gadobutrol in Rats

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Abstract
To evaluate the contrast kinetics of gadobutrol for interstitial MR lymphography. In 11 rats, 0.5 mL undiluted gadobutrol was injected subcutaneously into the hind paw. Contrast kinetics were measured in lymph nodes, kidney, liver, muscle, and blood of six animals using a time-resolved 2D GRE sequence. Additionally, high-resolution 3D T1-weighted data sets were obtained in five animals. Immediately after injection, a pronounced signal intensity loss was observed in popliteal, inguinal and aorto-iliac lymph nodes, followed by a continuous signal intensity increase. From the data peak concentrations of up to 78 mmol/L were estimated for selected lymph nodes. A contrast enhancement was also observed in kidneys, liver, muscle, and blood. Regional lymphatic vessels, the thoracic duct, as well as popliteal, inguinal, aorto-iliac, and axillary lymph node groups could be visualized with the high-resolution 3D MRI. Gadobutrol is suitable for interstitial MR lymphography, as it rapidly appears in the lymphatic system. Based on estimates of local tissue concentrations future studies have to assess the optimal contrast agent dosage. Furthermore, the investigation of metastatic lymph nodes is required to evaluate the further potential of gadobutrol for interstitial MR lymphography.