T₁‐based sensing of mammographic density using single‐sided portable NMR

Abstract

Purpose: A single-sided NMR instrument was used to investigate the ability of the T 1 relaxation constant to distinguish between regions of low and high mammographic density in human breast tissue.Methods: Measurements were performed on 5 breast slices obtained from 3 women undergoing breast reduction surgery or prophylactic mastectomy.Results: T 1 values measured in regions of high mammographic density in both the full breast slices (T 1 5 170 6 30 ms) and excised regions (T 1 5 160 6 30 ms) were found to be significantly different (P < .001) from those measured in regions of low mammographic density, in which T 1 5 120 6 10 ms was observed both in full slices and excised regions. There was no statistically significant difference between the T 1 values measured in the full breast slices and those measured in the excised regions. Conclusion:The findings suggest that portable NMR may provide a low-cost means of assessing mammographic density in vivo. K E Y W O R D S breast cancer risk, longitudinal spin-relaxation time constant (T 1 ), mammographic density, mammography, portable single-sided NMR | I NT ROD UCTI ONMammographic density (MD), also known as breast density, refers to the degree of radio-opacity of the breast as observed on an X-ray mammogram. Mammographic density is determined by the amount of the radiodense fibroglandular tissue (FGT), as opposed to the radiolucent adipose, or fat, tissue in the breast. In addition to having important implications for the efficacy of mammographic breast cancer risk screening, 1 MD is an independent risk factor for breast cancer, with women in the highest MD quartile having 4 to 6 times the risk of developing breast cancer than those in the lowest 10%, after normalization for body mass index and age. 2,3 Although the mammogram is still the current standard for Magn. Reson. Med. 2018;80:1243-1251.wileyonlinelibrary.com/journal/mrm

Transverse relaxation‐based assessment of mammographic density and breast tissue composition by single‐sided portable NMR

“…Following mammography, all slices were kept frozen (–80ºC) and later transferred to a freezer (−20ºC) at QUT’s Gardens Point campus, where they were kept until the portable‐NMR measurements. The use of frozen samples is consistent with the previously established experimental protocol; Supporting Information Figure illustrates the absence of significant effects of freezing on the spatial distribution of mammographic density of the samples.…”

“…We have recently shown that quantitative T 1 measurements using single‐sided portable NMR are capable of distinguishing between HMD and LMD regions in excised breast tissue slices . This suggests that portable NMR could potentially complement other nonionizing techniques measuring breast density‐equivalent quantities: ultrasound, bioimpedance, transillumination, and MRI .…”

“…In the present study, we follow up on the T 1 ‐based portable‐NMR quantification of MD reported earlier and explore the capabilities of T 2 ‐based portable‐NMR analysis for the assessment of MD in human breast tissue. Transverse spin relaxation in biological tissues is sensitive to the chemical composition and microscopic organization of the tissue .…”

“…To our knowledge, this is the first time ILT T 2 spectra have been used for compositional quantification of soft biological tissues. The key advantage of this approach is that, unlike T 1 ‐based measurements, it enables explicit quantification of the water:fat ratio in breast tissue. We discuss how this approach could be used for quantification of MD and evaluation of the relative amount of FGT within breast tissue.…”

Heparanase promotes Syndecan-1 expression to mediate fibrillar collagen and mammographic density in human breast tissue culturedex vivo

“…The individual breast explants were removed from the underlying sponge and placed in a well within a dry 24 well plate for Portable NMR measurements. For PG545 and E2 treatments, NMR T1 values of the samples were measured using saturation-recovery pulse sequence on a PM5 NMR-MOUSE instrument (Magritek, Wellington, New Zealand) as previously described (Tourell, Ali et al 2018, Huang, Ali et al 2019. All saturation-recovery curves exhibited mono-exponential recovery.…”