Prediction of different stages of rectal cancer: Texture analysis based on diffusion-weighted images and apparent diffusion coefficient maps

Table 1 Clinical and pathological characteristics of the patients

Characteristics	Value
Total patients	115
Age, yr	60.4 ± 15.8 (32-86)1
Gender
Male	67 (58.3)
Female	48 (41.7)
Primary mass location (from anal verge)
0-5 cm	35 (30.5)
5.1-10 cm	58 (50.4)
10.1-15 cm	22 (19.1)
Tumor differentiation
Moderate to high	89 (77.4)
Low	26 (22.6)
T stage
T1-2	31 (26.9)
T3-4	84 (73.1)
N stage
N0	63 (54.7)
N1-2	52 (45.3)

¹mean ± SD (range in years). Unless otherwise indicated, variables are expressed as frequencies (%).

Table 2 Features measured by different methods

Analysis method	Feature
ADC	ADCmin
	ADCmax
	ADCmean
Gray level co-occurrence matrix	Dissimilarity
	Sum average
	Difference variance
	Information correlation
Gray level run-length matrix	Gray level nonuniformity
	Run percentage
	Long run low gray level emphasis
	Run-length nonuniformity
Wavelet	SymletL
	SymletH
	SymletV
	SymletD

ADC: Apparent diffusion coefficient.

Table 3 Comparison of extracted features between T1-2 and T3-4 stage groups of rectal cancers

Method	Features	T1-2 (n = 31)	T3-4 (n = 84)	P value
DWIb=0	Dissimilarity	0.015 ± 0.008	0.018 ± 0.013	0.0172
	Sum average	2.068 ± 0.043	2.095 ± 0.067	0.0181
	Difference variance	0.140 ± 0.085	0.161 ± 0.192	0.1352
	Information correlation	0.185 ± 0.058	0.215 ± 0.067	0.0162
	Gray level nonuniformity	1.411 ± 0.351	1.730 ± 0.811	0.0191
	Run percentage	0.075 ± 0.012	0.083 ± 0.023	0.0092
	Long run low gray level emphasis	4.971 ± 4.897	5.840 ± 4.678	0.3162
	Run-length nonuniformity	3.266 ± 0.356	3.107 ± 0.445	0.0301
	SymletL	7.815 ± 1.568	8.295 ± 1.153	0.3672
	SymletH	0.627 ± 0.4011	0.516 ± 0.318	0.2211
	SymletV	0.335 ± 0.460	0.359 ± 0.298	0.8162
	SymletD	0.162 ± 0.158	0.177 ± 0.114	0.3712
DWIb=1000	Dissimilarity	0.018 ± 0.006	0.021 ± 0.018	0.0602
	Sum average	2.098 ± 0.058	2.122 ± 0.076	0.1211
	Difference variance	0.176 ± 0.105	0.198 ± 0.257	0.3482
	Information correlation	0.194 ± 0.041	0.217 ± 0.058	0.0531
	Gray level nonuniformity	1.443 ± 0.370	1.773 ± 0.815	0.0211
	Run percentage	0.075 ± 0.014	0.083 ± 0.023	0.0092
	Long run low gray level emphasis	8.801 ± 5.347	8.646 ± 7.836	0.9802
	Run-length nonuniformity	3.239 ± 0.371	3.084 ± 0.461	0.0361
	SymletL	8.461 ± 1.329	8.749 ± 0.984	0.9352
	SymletH	0.318 ± 0.387	0.336 ± 0.261	0.6962
	SymletV	0.293 ± 0.371	0.316 ± 0.249	0.5012
	SymletD	0.099 ± 0.124	0.118 ± 0.113	0.1372
ADC maps	ADCmin	0.328 ± 0.385	0.262 ± 0.367	0.7452
	ADCmax	2.513 ± 0.855	2.704 ± 0.885	0.2981
	ADCmean	1.099 ± 0.471	1.063 ± 0.521	0.7401
	Dissimilarity	0.062 ± 0.008	0.021 ± 0.011	0.0202
	Sum average	2.049 ± 0.038	2.063 ± 0.061	0.1712
	Difference variance	0.170 ± 0.122	0.218 ± 0.135	0.1372
	Information correlation	0.181 ± 0.041	0.199 ± 0.052	0.0551
	Gray level nonuniformity	1.367 ± 0.334	1.675 ± 0.739	0.0141
	Run percentage	0.073 ± 0.011	0.082 ± 0.021	0.0122
	Long run low gray level emphasis	4.006 ± 4.016	4.558 ± 4.364	0.8602
	Run-length nonuniformity	3.309 ± 0.498	3.168 ± 4.328	0.0681
	SymletL	6.789 ± 1.253	6.607 ± 1.435	0.5251
	SymletH	0.443 ± 0.187	0.530 ± 0.261	0.7911
	SymletV	0.473 ± 0.358	0.572 ± 0.350	0.1992
	SymletD	0.313 ± 0.224	0.301 ± 0.166	0.9051

¹Independent samples t-test, data are means ± SD.

²Mann-Whitney U test, data are medians ± interquartile range. DWI: Diffusion-weighted imaging; ADC: Apparent diffusion coefficient.

Table 4 Spearman correlation coefficients for independent predictors of T-stage

Features	T stage
	Rs	P value
DWIb=0
Dissimilarity	0.224	0.016
Sum average	0.221	0.018
Information correlation	0.227	0.015
Run-length nonuniformity	-0.204	0.029
DWIb=1000
Gray level nonuniformity	0.217	0.021
Run percentage	-0.197	0.035
Run-length nonuniformity	0.246	0.008
ADC map
Dissimilarity	0.218	0.019
Run percentage	0.236	0.011

DWI: Diffusion-weighted imaging; ADC: Apparent diffusion coefficient.

Table 5 Comparison of extracted features between N0 and N1-2 stage groups of rectal cancers

Method	Features	N0 (n = 63)	N1-2 (n = 52)	P value
DWIb=0	Dissimilarity	0.018 ± 0.015	0.017 ± 0.011	0.2182
	Sum average	2.099 ± 0.067	2.075 ± 0.053	0.0451
	Difference variance	0.151 ± 0.145	0.146 ± 0.181	0.3342
	Information correlation	0.211 ± 0.076	0.206 ± 0.063	0.0522
	Gray level nonuniformity	1.727 ± 0.623	1.559 ± 0.884	0.0391
	Run percentage	0.079 ± 0.022	0.078 ± 0.021	0.0712
	Long run low gray level emphasis	5.943 ± 5.191	5.527 ± 4.137	0.1222
	Run-length nonuniformity	3.082 ± 0.425	3.232 ± 0.493	0.0641
	SymletL	8.301 ± 1.159	7.945 ± 1.279	0.0582
	SymletH	0.487 ± 0.332	0.618 ± 0.349	0.0251
	SymletV	0.348 ± 0.351	0.378 ± 0.346	0.7022
	SymletD	0.158 ± 0.124	0.181 ± 0.449	0.1442
DWIb=000	Dissimilarity	0.021 ± 0.022	0.019 ± 0.012	0.1182
	Sum average	2.131 ± 0.075	2.098 ± 0.066	0.0261
	Difference variance	0.194 ± 0.203	0.192 ± 0.183	0.2912
	Information correlation	0.221 ± 0.053	0.198 ± 0.057	0.0351
	Gray level nonuniformity	1.759 ± 0.639	1.693 ± 0.836	0.0531
	Run percentage	0.081 ± 0.023	0.078 ± 0.022	0.0672
	Long run low gray level emphasis	9.539 ± 7.4371	7.835 ± 5.752	0.0172
	Run-length nonuniformity	3.562 ± 0.4327	3.210 ± 0.442	0.0701
	SymletL	8.837 ± 1.013	8.501 ± 1.264	0.0552
	SymletH	0.260 ± 0.316	0.374 ± 0.339	0.0332
	SymletV	0.314 ± 0.339	0.327 ± 0.248	0.3372
	SymletD	0.101 ± 0.104	0.125 ± 0.157	0.2362
ADC maps	ADCmin	0.645 ± 0.347	0.606 ± 0.539	0.7722
	ADCmax	2.642 ± 0.859	2.423 ± 0.857	0.0111
	ADCmean	1.208 ± 0.515	0.910 ± 0.446	0.0011
	Dissimilarity	0.021 ± 0.012	0.018 ± 0.010	0.4352
	Sum average	2.065 ± 0.062	2.049 ± 0.046	0.1852
	Difference variance	0.199 ± 0.161	0.218 ± 0.153	0.8132
	Information correlation	0.204 ± 0.483	0.182 ± 0.492	0.0211
	Gray level nonuniformity	1.665 ± 0.628	1.545 ± 0.709	0.0721
	Run percentage	0.079 ± 0.023	0.076 ± 0.021	0.0692
	Long run low gray level emphasis	4.470 ± 4.194	4.377 ± 4.385	0.5782
	Run-length nonuniformity	3.185 ± 0.387	3.317 ± 0.367	0.1061
	SymletL	6.902 ± 1.184	6.358 ± 1.555	0.0411
	SymletH	0.502 ± 0.247	0.511 ± 0.245	0.9601
	SymletV	0.510 ± 0.337	0.578 ± 0.338	0.3872
	SymletD	0.270 ± 0.133	0.343 ± 0.224	0.1421

¹Independent samples t-test, data are means ± SD.

²Mann-Whitney U test, data are medians ± interquartile range. DWI: Diffusion-weighted imaging; ADC: Apparent diffusion coefficient.

Table 6 Spearman correlation coefficients for independent predictors of N-stage

Features	N stage
	Rs	P value
DWIb=0
Sum average	-0.188	0.044
Gray level nonuniformity	-0.149	0.038
SymletH	0.211	0.024
DWIb=1000
Sum average	-0.209	0.025
Information correlation	-0.187	0.045
Long run low gray level emphasis	-0.223	0.017
SymletH	0.199	0.033
ADC maps
ADCmax	-0.204	0.029
ADCmean	-0.273	0.003
Information correlation	-0.199	0.033

DWI: Diffusion-weighted imaging; ADC: Apparent diffusion coefficient.