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. 2021 Sep 23;18(19):10003. doi: 10.3390/ijerph181910003

Table 1.

Summary of various state-of-the-art techniques employed for plaque characterization using coronary artery scans.

Dataset Preprocessing/ROI Segmentation Feature Extraction Feature Reduction/Feature Selection/
Feature Ranking/Organization
Detection Classification Task Outcomes *
[11] 599 VH-IVUS images of 10 patients Thresholding + HFCM-kNN model CLBT + OLBT SVM with radial basis function (RBF) Multiclass (PIT, TCFA and CaTCFA) and binary (TCFA and non-TCFA) For binary:
Pqacc.: 81.03
Pqsen.: 84.81
Pqspec.: 84.81
Precision: 84.81
For multiclass
Pqavg.acc.: 98.42 + 0.01
Kappa: 0.9198
[15] IVUS images Neuro Fuzzy Atheromatous plaque (fibrotic, lipidic, calcified, and normal) Pqavg.acc.: 98.9
[21] 300 IVUS frames of 10 patients Deformable models + Estimation borders by experts Co-occurrence matrix + LBP+ Mean value + Entropy + Geometrical features t-test RF Multiclass (DC, NC, FT, and FFT) Pqacc.: 85.65
[22] 553 IVUS frames of eight patients ROI Extraction + Otsu’s automatic thresholding + Pathological tissue detection CNN Multiclass (DC, NC, FT, FFT, Media) Overall accuracy: 93.5Pqacc.:DC: 98.5NC: 88.6FT: 91.1FFT: 90.0Media: 99.4
[25] IVUS images from 11 patients Manual segmentation by expert LBP + FOS
+GLCM + LEM + Extended GLRLM + Intensity
PCA RF Multiclass(DC, NC, FT, and FFT) AUC: 0.845, 0.704, 0.783
Pqacc.: 85.1,71.9,77.2
Pqsen.: 82,81.2, 80.6
Pqspec.: 87.1, 59.6, 75.9
(Respectively for Net1: FT/FFT or NC/DC
Net2: FT or FFT
Net3: NC or DC)
[27] 1000 IVOCT images from 47 patients Anisotropic diffusion + Polar Transformation+ Hough Transform Intensity + HOG + LBP + FV + k-means clustering SVM Multiclass
(normal, fibrous plaque, fibro-atheroma, plaque rupture, fibro-calcific plaque)
Pqavg.acc.: 90
With standard deviation of 0.02
[67] 770 OCT images of 5 patients ROI Extraction LBP+GLCM CNN (U Net) Multiclass (lipid tissue, fibrous tissue, background) Pqacc.: 95.8
[70] 435 IVUS images Polar Transformation + Gaussian filter +Median filter+ Anisotropic Diffusion filter Haralick’s +Laws’ textural feature SVM Two class (fibrotic plaque and normal) AUC: 0.97
Jaccard Index: 0.85
[72] 6556 OCT images from 49 patients ROI+ Dynamic programming + Gaussian filter CNN + Morphological features Wilcoxon signed rank test RF Binary class: (fibro-lipidic and fibrocalcific plaque) Fibro-lipidic plaque:
Pqsen.: 84.8
Pqspec.: 97.8
Fibro-calcific plaque:
Pqsen.: 91.4
Pqspec.: 95.7
[73] 18 CTA images
Total: 1786 cross sections with Non calcified plaque (NCP): 729, Calcified plaque (CP): 511, Mixed plaques: 546.
DRLSE RRS feature vector SVM (Gaussian kernel) Multiclass(calcified, non calcified and mixed plaques) Average precision: 92.6±1.9
Average recall: 94.3±2.1
[80] 60 IVUS images of 7 patients Anisotropic diffusion filter + Thresholding Deformable
models
Bayesian Two class (calcified and non-calcified plaque) AUC: 0.943
Pqspec.: 98.5
Pqsen.: 92.67
[83] 27 OCT pullbacks of 22 patients Gaussian filter + Thresholding + k-means LBP + GLCM WRP RF Multiclass (calcium, lipid pool, fibrous tissue, and mixed Tissue) Pearson’s correlation coefficient: 0.97 (FT)
[84] IVOCT images of 11 patients Gaussian filter + Otsu threshold filtering Attenuation coefficient + GLCM SVM (RBF) Multiclass (fibrous, calcification and lipid tissue) Pqacc.: 83
[88] IVUS images of 7 patients Multilevel discrete wavelet frame decomposition FOS + GLCM + LBP + RL + Wavelet Intensity values FuzCoC SVM (RBF) Multiclass (calcium, necrotic core, fibrous, and fibro-fatty) Pqavg.acc.: 81
[91] In-vivo dataset: VH-IVUS 2263 images of 10 patients
Ex-vivo dataset:64 images
Shadow detection using threshold NGL + LBP + MRL SVM and ECOC Multiclass(calcium, necrotic core, and fibro fatty) Kappa values: 0.639 (in-vivo) and 0.628 (ex-vivo)
[92] 50 OCT images from 3 patients Co-occurrence matrix + LBP+ Entropy + Mean value RF Multiclass (calcium, lipid pool, fibrous tissue, and mixed plaque) Pqacc.: 80.41
[93] 300 IVUS images of 7 patients Multilevel discrete wavelet frames decomposition + SOFM FOS + GLCM + RL + LBP + wavelets + LISA FaIRLiC Multiclass (DC, NC, FT, and FFT) Testing accuracy: 76.16%
[94] IVUS images of 7 patients Border detection + 2-D Kohonen’s self-organizing feature map (SOFM) FOS + GLCM + WF + RL + LBP FaIRLiC Multiclass(calcium, necrotic core, fibrous and fibro lipid) Average classification Accuracy on each frame: 73.67
[95] 2646 Coronary Tomography Angiography (CTA) images of 73 patients
(CP: 28, NCP: 15,
Normal: 30)
Adaptive Histogram Equalization Gabor Transform + Entropy ANOVA SVM (RBF and polynomial kernel) Multiclass (normal, non calcified and calcified) Pqacc.: 89.09
PqPPV: 91.70
Pqsen.: 91.83
Pqspec.: 83.70
[96] 316 IVUS images of 26 patients Thresholding + Polar transformation + Morphological operations FOS + FD (Box counting) + GLCM + GLRLM + LTE PCA Deep belief network Multiclass (DC, NC, FT, and FFT) Pqsen.: 92.8 ± 0.1,
Pqspec.: 85.1 ± 0.1,
Pqacc.: 88.4 ± 0.1,
PqPPV: 86 ± 0.1
PqNPV: 91.2 ± 0.1 (p < 0.05).
[97] IVUS images of 7 patients Adjacent pattern algorithm + Color moments of histogram + Statistical features SVM based CNN Multiclass (mild, moderate and severe) Pqacc.: 98.80, 98.80, 97.59
Pqsen.: 100, 100, 100
Pqspec.: 98.70, 98.70, 97.40
Precision: 85.71, 85.71, 75
Recall: 100, 100, 100
F-score: 0.92, 0.92, 0.99
(Respectively for Mild, moderate and severe)
[98] IVUS images from 11 patients Manual border segmentation FOS + GLCM + GLRLM + LBP + Intensity + Discrete wavelet features +LTE Genetic algorithm Hybrid ensemble classifier(FFNN+ RF+ Ada boost) Multiclass (DC, NC, FT, and FFT) Pqacc.: 82.8, 71.6, 77
AUC: 0.832, 0.697, 0.787
Pqsen.: 84.4, 81.9, 74.9
Pqspec.: 81.9, 57.6, 82.4
PqPPV: 71.2, 72.4, 91.7
PqNPV: 90.8, 70.1, 55.9
(Respectively for
Net1: FT/FFT or NC/DC
Net2: FT or FFT
Net3: NC or DC)
[99] 2685 IVUS images of 15 patients ImgTracer software GLCM + GLRLM + IH + GLDS + NGTDM + IM + Statistical feature matrix SVM (polynomial kernel 2nd order) Coronary and carotid plaque Pqacc.: 94.95
AUC: 0.95
Pqsen.: 92.88
Pqspec.: 96.61
PqPPV: 96.69
[100] 588 VH-IVUS images of 10 patients Fuzzy c means and k means with particle swarm optimization LBP + GLCM + MRL PCA SVM (RBF) TCFA and Non-TCFA Pqacc.: 98.61
[102] 4000 IVOCT images from 49 patients Cartesian Transformation CNN from ImageNet
ResNet50-v2 and DenseNet-121
Binary class: plaque (calcified plaque and lipid/fibrous plaque) and no plaque Pqacc.: 91.7
Pqsen.: 90.9
Pqspec.: 92.4
[103] CCTA of 150 patients CNN (U Net + V Net) Stenosis Detection and
Plaque classification
(calcified, partially calcified, noncalcified and no plaque)
Stenosis identification:
CCTA AI (p<0.001)
AUC: 0.870
Pqacc.: 86
Pqsen.: 88
Pqspec.: 85
PqPPV: 73
PqNPV: 94
Plaque classification:
AUC: 0.750
[104] 12,325 IVUS images from 100 patients IVUS and OCT registration + ROI segmentation CNN Binary (thin cap fibro-atherma and normal) AUC: 0.911
Pqspec.: 82.81
Pqsen.: 87.31
[105] 64 IVOCT images from 49 patients Otsu’s method + morphological operation Attenuation + Texture RF Multiclass (fibrotic, calcified, and lipid rich) Pqacc.: 81.5
[106] 4469 IOCT images of 48 patients Edge detection + Gaussian filter t-test CNN followed by post processing (Conditional Random Field + Morphological processing) Multiclass
(fibrocalcific,
fibro-lipidic and
other classes)
Pqacc.: 77.7 ± 4.1, 86.5 ± 2.3, 85.3 ± 2.5
Pqsen.: 80, 85, 84
Pqspec.: 95, 92, 92
(Respectively for fibrocalcific, fibro-lipidic, other classes)
p-value: 0.00027
[107] 700 OCT images of 28 patients CNN Multiclass (calcium, lipid tissue, fibrous tissue, mixed tissue, media and no visible tissue) Pqacc.: 96
[108] CCTA scans of 131 patients 3D Recurrent Convolutional Neural Network Multiclass (no plaque, non-calcified, mixed, calcified) and stenosis (no stenosis, non- significant, significant) Plaque analysis:
Pqacc.: 72, F1 score: 0.61
Cohen’s kappa: 0.60
Stenosis analysis:
Pqacc.: 81
F1 score: 0.78
Cohen’s kappa: 0.70
Pqsen.: 61
PqPPV: 83
[109] CCTA scans of 163 patients Recurrent convolutional neural network Multiclass(calcified, non-calcified and mixed) Plaque detection:
Pqacc.: 77
F1 score: 0.61
Cohen’s kappa: 0.61
Stenosis detection:
Accuracy: 80%
F1 score: 0.75
Cohen’s kappa: 0.68
Pqsen.: 61
PqPPV: 65
[110] CTA scans from 25 patients Multiplanar reformation technique 3D CNN U-Net
(Encoder-decoder)
Multiclass (calcified plaque, non-calcified plaque and mixed calcified plaque) Dice scores: 0.83, 0.73, 0.68
Pqsen.: 85, 76,72
PqPPV: 82, 69, 62
Respectively for CAP, NCAP, MCAP
[111] 2060 CTA images from 60 patients Higher-order spectra cumulants Multiple factor analysis + t-test SVM(RBF) Binary (calcified, noncalcified) Pqacc.: 95.83
Pqsen.: 94.54
Pqspec.: 97.13
PqPPV: 97.05

* AUC: Area Under Curve, PqPPV (%): Plaque Positive Predictive Value, PqNPV (%): Plaque Negative Predictive Value, Pqsen. (%): Plaque Sensitivity, Pqspec. (%): Plaque Specificity, Pqacc. (%): Plaque accuracy, Pqavg.acc. (%): Plaque average accuracy, Precision (%).