MR imaging of lymph nodes using Gadofluorine M: feasibility in a swine model at 1.5 and 3T]

Purpose: To investigate the potential of Gadofluorine M for targeted lymph node imaging in a human size animal model and on a clinical MR scanner at 1.5 and 31. Materials and Methods: Pelvic and cervical lymph nodes in a swine model were investigated prior to and 24 hours after intravenous administration of 50 mu mol/kg body weight Gadofluorine M, an experimental contrast agent. MR imaging was carried out on clinical 1.51 and 3T whole-body MR systems using clinically available coils and T1-weighted sequences. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) with respect to the surrounding tissue were assessed and compared using the Student's t-test. The Gd concentration in the lymph nodes (n = 43) was measured post mortem by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). Results: Gadofluorine M allowed for high signal and high contrast visualization of lymph nodes in all stations on post-contrast images with a significantly increased SNR and CNR (SNR pelvic lymph nodes post vs. pre: 46 +/- 7 vs. 14 +/- 3, SNR cervical lymph nodes post vs. pre: 105 +/- 64 vs. 32 +/- 21; CNR pelvic lymph node vs. muscle post vs. pre 28 +/- 5 vs. 0.2 +/- 0.5, CNR cervical lymph node vs. muscle post vs. pre 76 +/- 53 vs. 11 +/- 15, p < 0.05 for all comparisons). The SNR and CNR in the pelvis were further improved using 3T compared to 1.51 scanners (SNR lymph nodes 3 T vs. 1.5 T 84 +/- 6 vs. 46 +/- 7, CNR lymph node vs. muscle 3T vs. 1.5 T 53 +/- 9 vs. 28 +/- 5 respectively, p < 0.05). A high concentration of Gd in the lymph nodes was found (149 +/- 25 mmol Gd/L). Conclusion: Gadofluorine M accumulates in the lymph nodes and allows for selective targeted high contrast MR imaging of lymph node tissue in a large animal model using clinically available MR imaging techniques. 3T further improves SNR and CNR compared to 1.51.