In reply

Thank you for your interest and remarks regarding our publication “Influence of Age, BMI, Gender and Lumbar Level on T1ρ Magnetic Resonance Imaging of Lumbar Discs in Healthy Asymptomatic Adults”. We do share your view that T1ρ imaging possesses the potential of becoming a valuable tool in the assessment of the intervertebral discs.

As you mentioned, we cannot exclude that some of the healthy volunteers in our study might had changes in the MRI-Signal of the lumbar intervertebral discs as they are seen in symptomatic patients. This is amongst others due to the fact that we did not acquired additional sequences for disc evaluation, mainly T2 weighted images. As discussed under “Limitations” we made this decision in order to keep the overall examination time for the volunteers as short as possible. Furthermore, in our multidisciplinary study we wanted to focus on clinically asymptomatic adults, whether or not there might be changes in imaging that could be considered “degenerative”.

Regarding the effect of gender on possible disc degeneration we acknowledge that there are heterogeneous results in the literature at this point. The lack of a significant influence of gender on disc degeneration in our study is, for example, in accordance to the T1ρ study of Filippi et al. [1] and the large cadaveric study by Siemionow et al. [2].

Nonetheless, as you mentioned there is data in the literature which suggest that after menopause there might be accelerated disc degeneration in women.

Unfortunately, we did not collect the menopause status on our female volunteers and are therefore unable to re-evaluate the data as you suggested. Theoretically, it would be possible to compare the women of group A (as pre-menopausal) with group C (as post-menopausal) but, in this case, differentiating between the influence of age, which we showed to be significant, would be problematic. Furthermore, we believe that our study population, although large, might not be large enough to significantly show the potential influence of menopause. For a better understanding of the influence of menopause (and the potential of T1ρ in spinal imaging in general) we agree with you that larger population based studies are necessary.

• References

• 1 Filippi CG, Duncan CT, Watts R. et al. In vivo quantification of T1rho in lumbar spine disk spaces at 3 T using parallel transmission MRI. Am J Roentgenol 2013; 201: 110-116
• 2 Siemionow K, An H, Masuda K. et al. The effects of age, sex, ethnicity, and spinal level on the rate of intervertebral disc degeneration: a review of 1712 intervertebral discs. Spine (Phila Pa 1976) 2011; 36: 1333-1339