Letter to the Editor. Re: Comparing variability in measurement of subcutaneous tumors in mice using 3D thermal imaging and calipers

Abstract

We read with great interest the article entitled “Comparing variability in measurement of subcutaneous tumors in mice using 3D thermal imaging and calipers.”1 This research aimed to determine whether the previously observed lower variability on interoperator repeats in the measurement of subcutaneous tumors in mice could be reproduced in a larger dataset.1 We congratulate the authors for this original article and have sev- eral positive comments. The study evaluated a high number of samples. A total of 6,532 individual subcutaneous tumors from 27 laboratories across 289 studies and 153 operators were evalu- ated. The subcutaneous tumors were established in the flank area of 20 mouse strains (C57BL/6, Balb/C, R2G2, Nude, NSG) by inoculation of over 100 cell lines (MC38, TC-1, CT26, LNCaP, U87, 4T1, HT-29, PC3) and patient-derived xenografts. The tumors were scanned by 3D and thermal imaging system (3D- TI) and were measured multiple times by different operators using callipers. The tumor boundary was automatically deter- mined by the 3D-TI software in a process known as automatic segmentation and automatically measured algorithmically by the 3D-TI system.1 The methods used for tumor measurement in this article are replicable, but 3D-TI is an expensive tool as compared with calipers.