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

Abstract

Purpose: To quantify 3.0T (i) T1 and T2 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). Materials and Methods: MR relaxometry was performed over bilateral axillary regions at 3.0T in healthy female controls (105 LNs from 20 participants) and patients with BCRL (108 LNs from 20 participants). Quantitative T1 maps were calculated using a multi-flip-angle (20, 40, 60 degrees) method with B1-correction (dual-TR method, TR1/TR2=30/130 ms), and T2 maps using a multi-echo (TE=9–189 ms; 12 ms intervals) method. T1 and T2 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. Results: LN substructure relaxation times (mean ± standard deviation) in healthy controls were: T1 cortex=1435±391 ms, T1 hilum=714±123 ms; T2 cortex=102±12 ms, and T2 hilum=119±21 ms. T1 of the LN cortex was significantly reduced in the contralateral axilla of BCRL patients compared to the axilla on the surgical side (p<0.001) and compared to bilateral control values (p<0.01). The LN cortex T1 asymmetry discriminated cases vs. controls (p=0.004) in a multiple linear regression, accounting for age and BMI. Conclusion: Human 3.0T T1 and T2 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.

Fast whole brain MR imaging of dynamic susceptibility contrast changes in the cerebrospinal fluid (cDSC MRI)

“…There are some variations in the literature for CSF T1 and T2 values, 29 and the relaxation times of lymphatic fluid in the human body can be slightly shorter that those of CSF. 50 According to our simulations, a ±100 ms variation in CSF T1 can result in a ±50 ms optimal TR in T1-dominant sequences (for maximum contrast shown in Supporting Information Table S1) and a ±20 ms optimal TE in T2-dominant sequences, whereas a ±300 ms variation in CSF T2 can result in a ±40 ms optimal TR in T1-dominant sequences and a ±150 ms optimal TE in T2-dominant sequences. However, as shown in Equation (S8) in the Supporting Information, when TR is sufficiently long, variations in T1 and T2 values of CSF have little influence on the relative signal change in CSF before and after Gd injection (ΔS/S).…”

“…The maximum contrast in CSF signals before and after Gd injection, and therefore, the simulations and optimization of the proposed approach, is affected by the T1 and T2 values of CSF. There are some variations in the literature for CSF T1 and T2 values, 29 and the relaxation times of lymphatic fluid in the human body can be slightly shorter that those of CSF 50 . According to our simulations, a ±100 ms variation in CSF T1 can result in a ±50 ms optimal TR in T1‐dominant sequences (for maximum contrast shown in Supporting Information Table ) and a ±20 ms optimal TE in T2‐dominant sequences, whereas a ±300 ms variation in CSF T2 can result in a ±40 ms optimal TR in T1‐dominant sequences and a ±150 ms optimal TE in T2‐dominant sequences.…”

Systematic Review of Magnetic Resonance Lymphangiography From a Technical Perspective

“…LVs are also visualized in T 2 ‐weighted images; however, this may be improved by specific image optimization: Crescenzi et al . acquired images at 3.0 T with a range of echo times and were only able to clearly visualize LVs at TE = 121 msec, an echo time much shorter than is typical 61 …”

“…This may have arisen as a result of empirically determined optimal sequence parameters; however, this is not commented on within the literature. There is markedly little discussion of optimization of TR/TE within the articles included in this study: adequate image quality with the same protocol despite changes in field strength, and a lack of reported lymph vessel T 1 and T 2 times required for robust prospective protocol optimization, may explain the lack of studies documenting image optimization 61,78 …”

“…acquired images at 3.0 T with a range of echo times and were only able to clearly visualize LVs at TE = 121 msec, an echo time much shorter than is typical. 61 …”