Table 2 Ninety-two quantitative imaging features extracted from the multiregional spatial interaction (MSI) matrix to measure intratumoral spatial heterogeneity on PET/CT Habitat Map

From: Enhancing NSCLC recurrence prediction with PET/CT habitat imaging, ctDNA, and integrative radiogenomics-blood insights

Feature name

Feature description

MSI 1 – MSI 4

2nd-order statistical features.

MSI 5 – MSI 12

absolute tumor subregions volume (SR1 – SR8).

MSI 13 – MSI 20

interaction (absolute) between tumor subregions and border.

MSI 21 – MSI 27

interaction (absolute) between SR1 and the remaining subregions, i.e., MSI 21 = SR1 \(\cap\) SR2, MSI 22 = SR1 \(\cap\) SR3, …, MSI 27 = SR1 \(\cap\) SR8.

MSI 28 – MSI 33

interaction (absolute) between SR2 and SR3, SR4, SR5, S6, S7 and SR8, i.e., MSI 28 = SR2 \(\cap\) SR3, MSI 29 = SR2 \(\cap\) SR4, MSI 30 = SR2 \(\cap\) SR5, MSI 31 = SR2 \(\cap\) SR6, MSI 32 = SR2 \(\cap\) SR7, MSI 33 = SR2 \(\cap\) SR8.

MSI 34 – MSI 38

interaction (absolute) between SR3 and SR4, SR5, SR6, SR7 and SR8 i.e., MSI 34 = SR3 \(\cap\) SR4, MSI 35 = SR3 \(\cap\) SR5, MSI 36 = SR3 \(\cap\) SR6, MSI 37 = SR3 \(\cap\) SR7, MSI 38 = SR3 \(\cap\) SR8.

MSI 39 – MSI 42

interaction (absolute) between SR4 and SR5, SR6, SR7 and SR8 i.e., MSI 39 = SR4 \(\cap\) SR5, MSI 40 = SR4 \(\cap\) SR6, MSI 41 = SR4 \(\cap\) SR7, MSI 42 = SR4 \(\cap\) SR8.

MSI 43 – MSI 45

interaction (absolute) between SR5 and SR6, SR7 and SR8 i.e., MSI 43 = SR5 \(\cap\) SR6, MSI 44 = SR5 \(\cap\) SR7, MSI 45 = SR5 \(\cap\) SR8.

MSI 46 – MSI 47

interaction (absolute) between SR6 and SR7 and SR8 i.e., MSI 46 = SR6 \(\cap\) SR7, MSI 47 = SR6 \(\cap\) SR8.

MSI 48

interaction (absolute) between SR7 and SR8, i.e., MSI 48 = SR7 \(\cap\) SR8.

MSI 49 – MSI 56

percentage of tumor subregions volume (SR1 – SR8).

MSI 57 – MSI 64

normalized interaction (percentage) between tumor subregions and border.

MSI 65 – MSI 71

normalized interaction (percentage) between SR1 and the remaining subregions, i.e., MSI 65 = SR1 \(\cap\) SR2, MSI 66 = SR1 \(\cap\) SR3, …, MSI 71 = SR1 \(\cap\) SR8.

MSI 72 – MSI 77

normalized interaction (percentage) between SR2 and SR3, SR4, SR5, SR6, SR7 and SR8 i.e., MSI 72 = SR2 \(\cap\) SR3, MSI 73 = SR2 \(\cap\) SR4, MSI 74 = SR2 \(\cap\) SR5, MSI 75 = SR2 \(\cap\) SR6, MSI 76 = SR2 \(\cap\) SR7, MSI 77 = SR2 \(\cap\) SR8.

MSI 78 – MSI 82

normalized interaction (percentage) between SR3 and SR4, SR5, SR6, SR7 and SR8 i.e., MSI 78 = SR3 \(\cap\) SR4, MSI 79 = SR3 \(\cap\) SR5, MSI 80 = SR3 \(\cap\) SR6, MSI 81 = SR3 \(\cap\) SR7, MSI 82 = SR3 \(\cap\) SR8.

MSI 83 – MSI 86

normalized interaction (percentage) between SR4 and SR5, SR6, SR7 and SR8 i.e., MSI 83 = SR4 \(\cap\) SR5, MSI 84 = SR4 \(\cap\) SR6, MSI 85 = SR4 \(\cap\) SR7, MSI 86 = SR4 \(\cap\) SR8.

MSI 87 – MSI 89

normalized interaction (percentage) between SR5 and SR6, SR7 and SR8 i.e., MSI 87 = SR5 \(\cap\) SR6, MSI 88 = SR5 \(\cap\) SR7, MSI 89 = SR5 \(\cap\) SR8.

MSI 90 – MSI 91

normalized interaction (percentage) between SR6 and SR7 and SR8 i.e., MSI 90 = SR6 \(\cap\) SR7, MSI 91 = SR6 \(\cap\) SR8.

MSI 92

normalized interaction (percentage) between SR7 and SR8, i.e., MSI 92 = SR7 \(\cap\) SR8.

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