[A comparative study of Gd-DTPA and HSA-Gd-DTPA in magnetic resonance lymphography].

OBJECTIVE: To compare the effects of two contrast agents, Gd-DTPA and HSA-Gd-DTPA, in magnetic resonance (MR) lymphography. METHODS: Twelve New-Zealand rabbits were randomized into Gd-DTPA and HSA-Gd-DTPA groups with subcutaneous (interdigital skin fold) injection of the two contrast agents (0.2 ml of 0.5 mmol/L Gd(3+)) for MR lymphography of the popliteal lymph nodes examined in the axial and sagital orientation. T(1)-weighted, T1-weighted fat suppressed, and T(2)-weighted spin-echo (SE) images of the lymph nodes were obtained in plain scans. The post-contrast scanning started at 30 min, 1 h and 3 h after Gd-DTPA administration and at 10 min, 30 min and 60 min after HSA-Gd-DTPA injection to obtain T(1)-weighted images with identical imaging parameters. The signal intensity of popliteal lymph node was measured and the enhancement rate calculated. RESULTS: After subcutaneous injection, Gd-DTPA quickly entered blood circulation to result in obvious enhancement of the anterior-tibial vein and the urine and also in heterogeneous enhancement of the popliteal lymph nodes. HSA-Gd-DTPA did not enter the blood, causing obvious homogeneous enhancement of the lymphatic vessels and lymph nodes. HSA-Gd-DTPA resulted in higher enhancement rate than Gd-DTPA, and the enhancement rate in Gd-DTPA group decreased with time as opposed to that of the HSA-Gd-DTPA group. CONCLUSION: HSA-Gd-DTPA has better performance than Gd-DTPA in MR lymphography after subcutaneous administration.

[Magnetic resonance imaging findings of liver injury induced by three-dimensional conformal radiotherapy].

OBJECTIVE: To analyze the magnetic resonance imaging (MRI) findings of radiation-induced liver injury following three-dimensional conformal radiotherapy. METHODS: A retrospective review of the MRI data was conducted in 20 patients treated between September 2000 and October 2005, who suffered liver injuries induced by 1 or 2 three-dimensional conformal radiotherapy sessions for liver neoplasm. The patients underwent MR scans with T2-weighted sequences and T1-weighted sequences in both plain and Gd-DTPA enhanced MRI. Four patients with suspected tumor relapse suggested by MRI were pathologically confirmed to have radiation-induced liver injury. RESULTS: Acute radiation-induced liver injury was represented by large patches of liver edema consistent with the irradiation volume, showing low signal intensity on T1-weighted images (T1WI) and high signal intensity on T2-weighted images (T2WI) without arterial phase enhancement after Gd-DTPA injection. Delayed radiation-induced liver injury was manifested by slightly low-intensity signal on plain T1WI and slightly high-intensity signal on T2WI without obvious arterial phase enhancement following Gd-DTPA injection but with marked enhancement during the portal-venous and delayed phases. CONCLUSION: Radiation-induced liver injury presents characteristic MRI features, and plain and dynamic enhanced MRI can be of great value for its diagnosis.