3.0 T relaxation time measurements of human lymph nodes in adults with and without lymphatic insufficiency: Implications for magnetic resonance lymphatic imaging.

The purpose of this work was to quantify 3.0 T (i) T and T relaxation times of in vivo human lymph nodes (LNs) and (ii) LN relaxometry differences between healthy LNs and LNs from patients with lymphatic insufficiency secondary to breast cancer treatment-related lymphedema (BCRL). MR relaxometry was performed over bilateral axillary regions at 3.0 T in healthy female controls (105 LNs from 20 participants) and patients with BCRL (108 LNs from 20 participants). Quantitative T maps were calculated using a multi-flip-angle (20, 40, 60°) method with B correction (dual-T method, T /T  = 30/130 ms), and T maps using a multi-echo (T  = 9-189 ms; 12 ms intervals) method. T and T were quantified in the LN cortex and hilum. A Mann-Whitney U-test was applied to compare LN relaxometry values between patients and controls (significance, two sided, p < 0.05). Linear regression was applied to evaluate how LN relaxometry varied with age, BMI, and clinical indicators of disease. LN substructure relaxation times (mean ± standard deviation) in healthy controls were T cortex, 1435 ± 391 ms; T hilum, 714 ± 123 ms; T cortex, 102 ± 12 ms, and T hilum, 119 ± 21 ms. T of the LN cortex was significantly reduced in the contralateral axilla of BCRL patients compared with the axilla on the surgical side (p < 0.001) and compared with bilateral control values (p < 0.01). The LN cortex T asymmetry discriminated cases from controls (p = 0.004) in a multiple linear regression, accounting for age and BMI. Human 3.0 T T and T relaxation times in axillary LNs were quantified for the first time in vivo. Measured values are relevant for optimizing acquisition parameters in anatomical lymphatic imaging sequences, and can serve as a reference for novel functional and molecular LN imaging methods that require quantitative knowledge of LN relaxation times.