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Elastography –Accuracy in Children

August 31, 2018 7:04 am

Background: Transient elastography may help identify patients at greater risk for advanced fibrosis but there is a significant overlap between fibrosis stages and values with transient elastography. In some conditions, like fatty liver, elastography may be less helpful than in others (eg. chronic viral hepatitis).

A recent study (J Pediatr 2018; 198: 84-9) examined the results of transient elastography in 267 children (97 for calibration, 170 for validation) between 2006-2016. The median age was 13 years. Liver diseases included autoimmune (21%), viral (19%), fatty liver (11%), cholestatic (9%), primary sclerosing cholangitis (9%) and post-transplantation (12%).

Key findings:

Cut points to discriminate F3-F4 and F4 were >8.6 kPa and >11.5 with 81% and 84% accuracy, respectively in calibration cohort
To discriminate F3-F4 and F4 in validation cohort, these cut points, >8.6 kPa and >11.5, had accuracy of 67% and 75% respectively

Figure 2 provides much greater detail in the typical values for each Metavir stage. For example, in the calibration cohort, the median values and range were the following:

F0 6.0 (3.2-12.4)
F1 6.2 (3.2-75)
F2 5.8 (2.5-52.7)
F3 10.3 (4.9-32.6)
F4 20.5 (5.9-68.1)

In the validation cohort, values were similar:

F0 6.2 (3.0-75.0)
F1 7.1 (3.3-31.6)
F2 7.1 (2.5-52.7)
F3 9.6 (4.4-75.0)
F4 20.8 (6.8-75.0)

My take: Elastography in measuring liver stiffness is a lot like checking a CRP for inflammatory bowel disease. That is, it can be helpful but cannot be relied on the same way as many radiographic tests (eg. CT scans for appendicitis).

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