Automatic measurement of epithelium differentiation and classification of cervical intraneoplasia by computerized image analysis

Abstract

Background: The feasibility of evaluating an objective grading of cervical intraneoplasia lesions (CIN) is attempted using an automatic computerized system able to measure several valuable parameters with special reference to epithelium differentiation.

Methods: 4 groups of 10 images each were selected at random from 68 consensus images coming from 80 archival cervical biopsies, normal (n = 10), CIN 1 (n = 10), CIN 2 (n = 10), CIN 3 (n = 10). Representative images of lesions were captured from the microscopic slides and were analyzed using mathematical morphology, with special reference toVoronoï tessellation and Delaunay triangulation. Epithelium surface, nuclear and cytoplasm area, triangle edge and area, total and upper nuclear index were precisely measured in each lesion, and discriminant coefficients were calculated therewith. A dilation/erosion coefficient was automatically defined using triangle edge length and nuclear radius in order to measure the epithelium ratio of differentiation. A histogram ratio was also automatically established between total nuclei and upper nuclei on top of differentiated epithelium. With the latter two ratios added to the nucleo-cytoplasmic ratio, a cervical score able to classify CIN is proposed.

Results: There is a quasi-linear increase of mean cervical score values between normal epithelium and CIN 3: (27) for normal epithelium, (51) for CIN 1, (78) for CIN 2 and (100) for CIN 3, with significant differences (P < 0.05).

Conclusion: Our results highlight the possibility of applying a cervical score for the automatic grading of CIN lesions and thereby assisting the pathologist for improvement of grading. The automatic measure of epithelium differentiation ratio appears to be a new interesting parameter in computerized image analysis of cervical lesions.

Figure 1

The image analysis process till Delaunay triangulation.

Figure 2

Calculation of the dilation/erosion coefficient.

Figure 3

Measurement of the differentiated epithelium.

Figure 4

Measurement of the nuclei histogram (total and upper nuclei).

Figure 5

Data on ratios (mean ± SD). Statistical comparisons for each ratio (Normal vs CIN1; CIN1 vs CIN2; CIN2 vs CIN3) are significant (P < 0.05), except for upper nuclei histogram ratio (CIN1 vs CIN2).