TABLE 2.
Details of Investigated Imaging Features from PET and CT, Including 27 Habitat-Related Features and 13 Conventional Imaging Markers
| Type | Details | n |
| Habitat-related features | ||
| Change of individual habitat region’s burden | ∆Volhabitat i where i = 1,2,3 | 3 |
| Change for connected habitat region burden measured by MSI matrix | ∆MSI i, where i = 1,…,9 | 9 |
| Habitat progression via spatiotemporal habitat evolution (SHE) matrix | SHE i, where i = 1,…,15 | 15 |
| Conventional features | ||
| Tumor and node burden from CT | (a) Pre.Vol: volume from pre-RT CT; (b) Mid.Vol: volume from mid-RT CT; (c) ∆VolCT: volume change | 3 |
| Metabolic activity of tumor and node regions from PET | Pre-RT PET: (a) Pre.SUVmax; (b) Pre.MTV2.5; (c) Pre.MTVFCM | 9 |
| Mid-RT PET: (d) Mid.SUVmax; (e) Mid.MTV2.5; (f) Mid.MTVFCM | ||
| Change: (g) ∆SUVmax; (h) ∆MTV2.5; (i) ∆MTVFCM | ||
| Radiomics signature of tumor | Radiomics: prediction model built from set of 600 radiomics features (321 from CT, 279 from PET SUV) | 1 |
∆ = mid − pre; pre-RT = pretreatment radiotherapy; mid-RT = midtreatment radiotherapy; MTVFCM = MTV adaptively defined using fuzzy c-means algorithm; MTV2.5 = MTV defined using SUV of 2.5 as cutoff.