Table 1 Summary of the previous studies performing classification of neurological disorders using MRI and with clear data leakage (see also Supplementary Table S1 for a detailed description).

From: Effect of data leakage in brain MRI classification using 2D convolutional neural networks

Disorder

References

Groups (number of subjects)

Machine learning model

Data split method

Type of data leakage

Accuracy (%)

AD/MCI

Gunawardena et al.36

AD-MCI-HC (36)

2D CNN

4:1 train/test slice-level split

Wrong split

96.00

Hon and Khan21

AD-HC (200)

2D CNN (VGG16)

4:1 train/test slice-level split

Wrong split

96.25

Jain et al.37

AD-MCI-HC (150)

2D CNN (VGG16)

4:1 train/test slice-level split

Late and wrong split

95.00

Khagi et al.38

AD-HC (56)

2D CNN (AlexNet, GoogLeNet,ResNet50, new CNN)

6:2:2 train/validation/test slice-level split

Wrong split

98.00

Sarraf et al.22

AD-HC (43)

2D CNN (LeNet-5)

3:1:1 train/validation/test slice-level split

Wrong split

96.85

Wang et al.39

MCI-HC (629)

2D CNN

Data augmentation + 10:3:3 train/validation/test split by MRI slices

Wrong split and augmentation before split

90.60

Puranik et al.40

AD/EMCI-HC (75)

2D CNN

17:3 train/test split by MRI slices

Wrong split

98.40

Basheera et al.41

AD-MCI-HC (1820)

2D CNN

4:1 train/test split by MRI slices

Wrong split

90.47

Nawaz et al.42

AD-MCI-HC (1726)

2D CNN

6:2:2 slice level split

Wrong split

99.89

  1. AD Alzheimer’s disease, HC healthy controls, MCI mild cognitive impairment.