Background Fractal dimension of a histologic image can be interpreted as a snapshot of an evolving process. In fish the liver represents the main source for lipid storage. The liver parenchyma involved in lipid accumulation acquires a pitted texture that resembles an irregular "network". The aims of the present study are: 1) to assess the Fractal Dimension of lipid accumulation in histologic sections of liver from reared Solea senegalensis 2) to compare Fractal Dimension with area involved by lipid accumulation obtained through histopathological image segmentation and histological scoring, and 3) to discuss functional meaning of the fractal pattern of lipid accumulation. Methods Liver histological sections of 36 soles were clustered into mild, moderate or severe, giving a score of 2, 3 and 4, respectively, to the lipid accumulation. When these changes were not present, the livers were considered to be normal (score 1). Digital image analysis, performed by a pathologist in blind, was carried out on five randomly selected fields of each section by means of a manual selection (segmentation) of two sets of pixel (cytoplasmic “empty area” and the remaining parenchyma). Computing of Fractal Dimension was performed with box counting method on the same images. Receiver Operating Characteristic (ROC) curve was used to compare the accuracy of the diagnostic methods employed. Results Histological scoring ranged from 2 to 4. No case had scoring equal to 1. Empty area ranged from 34,02 to 87,03%. Box counting Fractal Dimension ranged from 1.45 to 1.63. The histological scoring did not correlate with the Fractal Dimension. The comparison between Fractal Dimension computing and histological scoring showed a fail accuracy (area under the ROC curve - AUC was 0.545) while the comparison between segmentation method and histological scoring was highly accurate (area under the ROC curve - AUC was 0.925). Conclusions The box counting Fractal Dimension as presented can be useful in interpreting the process of lipid accumulation in the fish liver, although the measure of area by segmentation showed higher values of sensitivity and specificity when compared to the histological scoring (gold standard), and can be proposed as a reliable digital image analysis method to assist the pathologist.
How severe is the lipid accumulation in fish liver? A fractal answer
BIANCO, CARLO;SIRRI, RUBINA;SARLI, GIUSEPPE;OSTANELLO, FABIO;BONALDO, ALESSIO;MANDRIOLI, LUCIANA
2013
Abstract
Background Fractal dimension of a histologic image can be interpreted as a snapshot of an evolving process. In fish the liver represents the main source for lipid storage. The liver parenchyma involved in lipid accumulation acquires a pitted texture that resembles an irregular "network". The aims of the present study are: 1) to assess the Fractal Dimension of lipid accumulation in histologic sections of liver from reared Solea senegalensis 2) to compare Fractal Dimension with area involved by lipid accumulation obtained through histopathological image segmentation and histological scoring, and 3) to discuss functional meaning of the fractal pattern of lipid accumulation. Methods Liver histological sections of 36 soles were clustered into mild, moderate or severe, giving a score of 2, 3 and 4, respectively, to the lipid accumulation. When these changes were not present, the livers were considered to be normal (score 1). Digital image analysis, performed by a pathologist in blind, was carried out on five randomly selected fields of each section by means of a manual selection (segmentation) of two sets of pixel (cytoplasmic “empty area” and the remaining parenchyma). Computing of Fractal Dimension was performed with box counting method on the same images. Receiver Operating Characteristic (ROC) curve was used to compare the accuracy of the diagnostic methods employed. Results Histological scoring ranged from 2 to 4. No case had scoring equal to 1. Empty area ranged from 34,02 to 87,03%. Box counting Fractal Dimension ranged from 1.45 to 1.63. The histological scoring did not correlate with the Fractal Dimension. The comparison between Fractal Dimension computing and histological scoring showed a fail accuracy (area under the ROC curve - AUC was 0.545) while the comparison between segmentation method and histological scoring was highly accurate (area under the ROC curve - AUC was 0.925). Conclusions The box counting Fractal Dimension as presented can be useful in interpreting the process of lipid accumulation in the fish liver, although the measure of area by segmentation showed higher values of sensitivity and specificity when compared to the histological scoring (gold standard), and can be proposed as a reliable digital image analysis method to assist the pathologist.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
