## 4 Discussion
We found that the eccentricity of pre-ablation SHSs in the squamous region was strongly correlated with the reduction of BE length at follow-up (Table 4), but only for less elderly patients. This suggests that age might be an important factor that could affect the RFA treatment response. It also suggests that squamous and BE SHSs may play different roles in RFA-treated BE. One obvious difference is that BE SHSs were directly ablated during the treatment, while the squamous SHSs were not. It should be noted that in this study, the SHSs may result from previous ablations for those previously treated patients. Further studies with larger enrollment and treatment naive patients are needed to confirm the roles of squamous SHSs [25,26]. We also found that SHSs in the BE region were significantly shallower, more vertical, less eccentric and more regular compared to subsquamous SHSs (Table 2). This is likely the case because BE glands are usually found in the epithelium, but subsquamous glands are often below the epithelium. Another possible explanation is that OCT light penetration to deeper structures was more limited in the BE region compared with the squamous region. The high irregularity of SHSs in the squamous region may be associated with previous ablation treatments. There were considerable differences for the roles of SHSs between LGD and HGD/IMC patients. For example, as shown, BE with shallower SHSs were more likely to achieve neo-SE for HGD/IMC patients. The correlations of several subsquamous SHS characteristics and the reduction of BE length were also different between HGD/IMC and LGD patients. However, the results here should be interpreted with caution because the highest pathology diagnosis may not necessarily correspond to the time of VLE imaging. [PERSON] et al. [11] reported that most of the SHSs in VLE are normal histological features. In this study, we applied a criterion to differentiate normal lymphatic ducts from glands based on their longitudinal axis length. Although empirical, this was effective in excluding most of the normal lymphatic ducts from glands from unwanted analysis. However, it may be difficult to differentiate between glands and vessels in VLE due to their similar intensity. Newly developed functional imaging methods such as OCT angiography can be applied to identify depth-resolved vasculature [27,28]. Moreover, we could not exclude the possibility that there might be other normal features that were detected as \"gland-like\" structures by the algorithm. Nevertheless, the algorithm can be used with laser marking technology [29,30] to further validate the nature of SHSs found in VLE with histopathology of co-registered excisional biopsies. There are several limitations in this study. First, the sample size is relatively small. Second, most of the patients enrolled in this study were not treatment naive and had relatively short segment BE. Third, the SHSs detected by the algorithm were not validated against histopathology, and the correlation between SHS findings and dysplasia cannot be established. Fourth, the study is retrospective. Lastly, VLE data has motion artifacts such as non-uniform rotational distortion (NURD). Several post-processing algorithms [31, 32, 33] for correcting NURD have been proposed, but methods for high accuracy and full automation are still needed. Therefore, the quantitative shape descriptor results should be interpreted as an estimate of the actual SHS morphology.