Quantitative histological-hemodynamic correlations in cirrhosis

Abstract

We have previously shown, in a semiquantitative analysis of liver biopsies showing cirrhosis, that thickness of fibrous septa separating cirrhotic nodules and small size of cirrhotic nodules correlated independently with portal pressure (as determined by the hepatic venous pressure gradient; HVPG) and were independent predictors of the presence of clinically significant portal hypertension (PH). This study aimed to confirm these results using quantitative analysis of these biopsies using digital image analysis. Biopsies of 42 patients with cirrhosis and HVPG measurements within 6 months of the biopsy were included in the study. The following parameters were scored quantitatively and without knowledge of HVPG results: total fibrosis area, septal thickness, nodule size, and number of nodules per millimeter of length of liver biopsy. Fibrosis area was the only parameter that independently correlated with HVPG (r = 0.606; P < 0.0001). Correlation was significant, even among patients with clinically significant PH (r = 0.636; P < 0.005). Fibrosis area and nodule size were both independently predictive of the presence of clinically significant PH (r = 0.57; P = 0.003).

Conclusions: On quantitative analysis, fibrosis area was the parameter that correlated best with HVPG and the presence of clinically significant PH. Beyond pathophysiological implications, this also has methodological implications that are discussed in this article.

Figure 1

Quantitative measurements. Septal width was assessed by measuring the distance between two cirrhotic nodules at multiple points (at least 3, red arrows). Nodule size was assessed as the maximum length along the long axis of the biopsy (black arrows).

Figure 2

Correlation between hepatic venous pressure gradient (HVPG) and total fibrosis area in all biopsy slides (A) and in biopsies of patients with clinically significant portal hypertension (B).

Figure 2

Correlation between hepatic venous pressure gradient (HVPG) and total fibrosis area in all biopsy slides (A) and in biopsies of patients with clinically significant portal hypertension (B).

Figure 3

Liver biopsy of patients with (A) and without (B) clinically significant portal hypertension (Masson stain). In A, there are multiple small nodules (<1mm) separated by wide fibrous septa which are >1mm thick. Fibrosis area was estimated at 46% and HVPG was 28 mmHg. In B, there are multiple large nodules (>2mm) separated by thin fibrous septa which are <1mm thick. Fibrosis area was estimated at 10% and HVPG was 6 mmHg.

Figure 3

Liver biopsy of patients with (A) and without (B) clinically significant portal hypertension (Masson stain). In A, there are multiple small nodules (<1mm) separated by wide fibrous septa which are >1mm thick. Fibrosis area was estimated at 46% and HVPG was 28 mmHg. In B, there are multiple large nodules (>2mm) separated by thin fibrous septa which are <1mm thick. Fibrosis area was estimated at 10% and HVPG was 6 mmHg.

Figure 4

Three models of cirrhosis and theoretical biopsy slides from each model. A) small perfectly rounded nodules are uniformly distributed throughout the liver, fibrous septae are thick and fibrosis area is large; B) large nodules are uniformly distributed throughout the liver, fibrous septae are thin and fibrous area is smaller; C) real model in which nodules are neither uniformly distributed nor are perfectly rounded. Consequently, septal width is also variable.

Figure 5

Biopsies exemplifying problems confronted with quantitative analysis (trichrome stain). In A there are variably sized irregular nodules with thin and very delicate fibrous septa. The irregular outline of the nodules and the fibrosis pattern would be very difficult to assess quantitatively. The patient did not have clinically significant portal hypertension. In B there are variably sized nodules with a very large nodule seen on the left edge and multiple small nodules with irregular outlines and thick fibrous septae. While the semiquantitative analysis would conclude that nodules are small, size would be falsely overrepresented in a quantitative analysis by averaging the size of the large nodule. The patient had clinically-significant portal hypertension.

Figure 5

Biopsies exemplifying problems confronted with quantitative analysis (trichrome stain). In A there are variably sized irregular nodules with thin and very delicate fibrous septa. The irregular outline of the nodules and the fibrosis pattern would be very difficult to assess quantitatively. The patient did not have clinically significant portal hypertension. In B there are variably sized nodules with a very large nodule seen on the left edge and multiple small nodules with irregular outlines and thick fibrous septae. While the semiquantitative analysis would conclude that nodules are small, size would be falsely overrepresented in a quantitative analysis by averaging the size of the large nodule. The patient had clinically-significant portal hypertension.