Journal List > J Korean Soc Radiol > v.79(3) > 1099989

Jeong, Kang, Kim, and Kim: Breast Ultrasound Computer-Aided Diagnosis: Analysis of Types of Errors

Abstract

Purpose

The aim of this study was to evaluate the diagnostic performance of breast ultrasound (US) computer-aided diagnosis (CAD) to distinguish between benign and malignant lesions and analyze features of lesions interpreted with errors retrospectively.

Materials and Methods

Three hundred and sixteen women with 375 breast lesions were enrolled. We assessed the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Additionally, we evaluated the causes and patterns of the misinterpretation in the false positive and negative groups.

Results

The accuracy, sensitivity, specificity, PPV, and NPV of breast US-CAD were 80.3%, 83.3%, 79.8%, 37.7%, and 97.0%, respectively. There were 8 false negative lesions that were oval in shape and in parallel orientation. There were 66 false positive lesions. The greatest number of errors entailed inappropriate demarcation due to heterogeneous echogenicity, etc. The second exhibited suspicious features with good demarcation and description but were confirmed as benign histologically. The third entailed a benign lesion with suspicious features, such as abscesses. The smallest portion with good demarcations and descriptions indicating benign status exhibited possible malignancy as a final conclusion.

Conclusion

Breast US-CAD is expected to be helpful in avoiding unnecessary biopsies due to its high NPV. Therefore, operators need to know the characteristics of lesions prone to misinterpretation.

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Fig. 1
Imaging findings from a 56-year-old woman who had ductal carcinoma in situ, an example of a false negative interpretation of CAD. CAD interpretation of this lesion as possibly benign with oval parallel, circumscribed hypoechoic features. CAD misinterpretation of ‘well-circumscribed’ breast carcinomas as benign lesions. CAD = computer-aided diagnosis
jksr-79-114f1.tif
Fig. 2
Imaging findings from a 60-year-old woman who had an involuting fibroadenoma, an example of first type error of a false positive interpretation of CAD. This breast lesion was known as an involuting fibroadenoma. Heterogeneous echogenicity of this mass is applied to CAD, and due to its heterogeneity, the lesion shape is read as an irregular shape with a microlobulated margin, and the final assessment is possibly malignancy. CAD = computer-aided diagnosis
jksr-79-114f2.tif
Fig. 3
Imaging findings from a 41-year-old woman who had fibrocystic change, an example of second type error of false positive interpretation of CAD. An irregular-shaped not parallel hypoechoic lesion is found on US. CAD reveals proper demarcation with irregular, not parallel, spiculated hypoechoic description with possible malignant conclusion. Due to its suspicious features, US-guided biopsy is found on US performed, and fibrocystic change is found on US confirmed. It is found on US an inevitable false positive case in the clinical setting. CAD = computer-aided diagnosis, US = ultrasound
jksr-79-114f3.tif
Fig. 4
Imaging findings from a 61-year-old woman who had fibrocystic change, which is an example of fourth type error of false positive interpretation on CAD. US reveals an oval parallel circumscribed hypoechoic mass. CAD also describes this lesion as an oval parallel circumscribed hypoechoic mass without posterior features. However, the final assessment was possible malignancy. A US-guided biopsy was performed and fibrocystic change was confirmed. This was a real error in the interpretation of CAD. CAD = computer-aided diagnosis, US = ultrasound
jksr-79-114f4.tif
Table 1.
Characteristics of 327 Benign Lesions and 48 Malignant Lesions
Pathology Number
170 benign/borderline lesions
  Atypical ductal hyperplasia 2
  Intraductal papilloma 13
  Radial scar 2
  Phyllodes tumor 2
  Flat epithelial atypia 2
  Columnar cell hyperplasia 3
  Sclerosing adenosis 3
  Abscess 1
  Chronic inflammation 3
  Adenosis 2
  Fat necrosis 4
  Fibrocystic change 51
  Fibroadenoma 62
  Fibroadenomatous hyperplasia 5
  Parasite 1
  Sclerosing fibrosis 1
  Stromal fibrosis 5
  Tubular adenoma 2
  Usual ductal hyperplasia 1
  Hamartoma 3
  Florid ductal hyperplasia 1
  Inflammatory lymph node 1
48 confirmed malignancy
  Invasive ductal carcinoma 35
  Ductal carcinoma in situ 6
  Mucinous carcinoma 5
  Papillary carcinoma 1
  Metaplastic carcinoma 1
157 breast lesions without changes for more than 2 years 157
Total 375
Table 2.
Interobserver Agreement between Radiologists and CAD System
Lexicon Kappa Value Agreement
Shape 0.526 Moderate
  Oval
  Round
  Irregular
Orientation 0.590 Moderate
  Parallel
  Not parallel
Margin 0.377 Fair
  Circumscribed
  Indistinct
  Angular
  Microlobulated
  Spiculated
Echogenicity 0.381 Fair
  Anechoic
  Hyperechoic
  Complex cystic and solid
  Hypoechoic
  Isoechoic
  Heterogeneous
Posterior features 0.385 Fair
  No posterior features
  Enhancement
  Shadowing
  Combined pattern
  Final assessment
  Possibly benign 0.422 Moderate
  Possibly malignancy (≥ C4A)
  Possibly benign 0.356 Fair
  Possibly malignancy (≥ C4B)

C4A = category 4A, low suspicion for malignancy, C4B = category 4B, moderate suspicious for malignancy, CAD = computer-aided diagnosis

Table 3.
Diagnostic Performance of CAD System and Radiologists
  Pathology Malignant Benign Total
CAD Possibly malignant 40 66 106
Possibly benign 8 261 269
Total 48 327 375
Accuracy (%) 80.3 PPV 37.7
Sensitivity (%) 83.3 NPV 97.0
Specificity (%) 79.8    
Radiologist (Cutoff: C4A) ≥ C4A 47 99 146
< C4A 1 228 229
Total 48 327 375
Accuracy (%) 73.3 PPV 32.2
Sensitivity (%) 97.9 NPV 99.6
Specificity (%) 69.7    
Radiologist (Cutoff: C4B) ≥ C4B 35 7 42
< C4B 13 320 333
Total 48 327 375
Accuracy (%) 94.7 PPV 83.3
Sensitivity (%) 72.9 NPV 96.1
Specificity (%) 97.9    

C4A = category 4A, lo suspicion for malignancy, C4B = category 4B, moderate suspicious for malignancy, CAD = computer-aided diagnosis, NPV = negative predictive value, PPV = positive predictive value

Table 4.
Patterns of False Negative Interpretations of CAD System
No Shape Orientation Margin Echogenicity Pathology Size (cm) Radiologists’ Category
1 Irregular Parallel Microlobulated Isoechoic Mucinous carcinoma 1.1 C3
2 Oval Parallel Circumscribed Hypoechoic Invasive ducal carcinoma 1.4 C4B
3 Oval Parallel Circumscribed Complex cystic and solid Ductal carcinoma in situ 1.8 C4A
4 Oval Parallel Microlobulated Hypoechoic Mucinous carcinoma 1.3 C4A
5 Oval Parallel Circumscribed Hypoechoic Mucinous carcinoma 0.3 C4A
6 Oval Not parallel Circumscribed Isoechoic Invasive ducal carcinoma 2.2 C4A
7 Oval Parallel Circumscribed Isoechoic Papillary carcinoma 0.3 C4A
8 Oval Parallel Microlobulated Complex cystic and solid Invasive ducal carcinoma 1.2 C4B

C3 = category 3, probable benign finding, C4A = category 4A, low suspicion for malignancy, C4B = category 4B, moderate suspicious for malignancy, CAD = computer-aided diagnosis

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