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Table 4 Predictive modelling characteristics of studies using traditional machine learning-based semi-automated AI methods

From: Comparative performance of fully-automated and semi-automated artificial intelligence methods for the detection of clinically significant prostate cancer on MRI: a systematic review

Study

No. of patients

Training set

Validation set

Test set

Algorithm

MRI input

IR

IS

Discriminative features

No. of features used for training

Outcome

Zone

Analysis

Evaluation strategy

Bonekamp [25]

316

183

NR

133

RF

T2WI, ADC, b = 1500

No

Manual

First-order, volume, shape, texture

NR

csPCa vs iPCa or benign lesions

WP or PZ or TZ

Per lesion and per patient

Internal hold-out

Min [26]

280

187

NR

93

LR

T2WI, ADC, b = 1500

No

Manual

Intensity, shape, texture, wavelet

9

csPCa vs iPCa

WP

Per lesion

Internal hold-out

Kwon [27]

344

204

tenfold CV

140

CART, RF, LASSO

T2WI, DWI, ADC, DCE

Rigid

No

Intensity

54

csPCa vs iPCa or benign lesions

PZ or TZ

Per lesion

Internal hold-out

Castillo [28]

107

80%

20% of training (100 random repeats)

20%

LR, SVM, RF, NB, LQDA

T2WI, DWI, ADC

HPa

Manual

Shape, local binary patterns, GLCM

NR

csPCa vs iPCa

WP

Per lesion, Per patient

Mixed hold-out

Bleker [29]

206

130

NR

76

RF, XGBoost

T2WI, b = 50, b = 400, b = 800, b = 1400, ADC, Ktrans

No

Manual

Intensity, texture

NR

csPCa vs iPCa or benign lesions

PZ

Per lesion

Internal hold-out

Li [30]

381

229

NR

152

LR

T2WI, ADC

No

Manual

Intensity, age, PSA, PSAd

15

csPCa vs iPCa or benign lesions

WP

Per lesion

Internal hold-out

Woźnicki [31]

191

151

fivefold CV

40

LR, SVM, RF, XGBoost, CNN

T2WI, ADC

No

Manual

Intensity, shape, PI-RADS, PSAd, DRE

15

csPCa vs iPCa or benign lesions

WP

Per patient

Internal hold-out

Bevilacqua [32]

76

48

threefold CV

28

SVM

ADC, b = 2000

No

Manual

Intensity

10

csPCa vs iPCa

WP

Per lesion

Internal hold-out

Toivonen [33]

62

62

LPOCV

N/A

LR

T2WI, ADC, Ktrans, T2 map

No

Manual

Intensity, Sobel, texture

NR

csPCa vs iPCa

WP

Per lesion

LPOCV

Antonelli [34]

164

134

NR

30

PZ: LinR

TZ: NB

ADC, DCE

Rigid

Manual

Texture, PSAd

NR

csPCa vs iPCa

PZ or TZ

Per lesion

fivefold CV

Yoo [35]

427

271

48

108

CNN, RF

ADC, DWI

No

No

First-order statistics of deep features

90

csPCa vs iPCa or benign lesions

WP

Per slice, Per patient

tenfold CV

Hiremath [36]

592

368

threefold CV

224

AlexNet or DenseNet and Nomogram

T2WI, ADC

Rigid, affine

Manual

Deep learning imaging predictor, PI-RADS, PSA, gland volume, tumour volume

NR

csPCa vs iPCa or benign lesions

WP

Per patient

External hold-out

  1. ADC, apparent diffusion coefficient; CART, classification and regression trees; CNN, convolutional neural networks; GLCM, grey level co-occurrence matrix; HP, histopathology; IR, image registration; IS, image segmentation; LASSO, least absolute shrinkage and selection operator; LinR, linear regression; LQDA, linear and quadratic discriminant analysis; LR, logistic regression; NB, naïve Bayes; PI-RADS, prostate imaging-reporting and data system; PSA, prostate-specific antigen; PSAd, prostate-specific antigen density; RF, random forests; SVM, support-vector machines
  2. aHistopathology images registered with T2-weighted images using specialised software