MR Elastography Stages Liver Fibrosis
New data suggests that MR Elastography can provide accurate data used to diagnose the stage of liver fibrosis. This data, in addition to previous data collected, may foster a move to replace liver biopsy with this less invasive modality. Another drawback of biopsy is the unreliability of biopsy results, as described in the report of study findings in Radiology.
The team compared results from MR Elastography to aspartate aminotransferase-to-platelet ratio index (APRI), that is most commonly used to determine the stage of hepatic fibrosis. APRI is determined based on histopathologic assessment of tissue procured with liver biopsy using METAVIR scoring. That system determines fibrosis grade on a scale from 0 to 4.
Almost ninety patients participated in this trial; 37 men and 51 women. The mean age of the participants was 54 years. Patients underwent MR scanning within two days of liver biopsy and histopathologic analysis was also completed within that same time frame. MR Elastography was completed with transmission of mechanical waves through the liver. Disease assessment was based on small cyclic displacement of the spins of the liver, considering the phase-contrast spin-echo sequence.
Data from both these techniques was compared. Determination of fibrosis based on MR results incorporated cutoff points determined by receiver operating characteristics (ROC) curve analysis.
MR Elastography scores were 0.999, 0.997, and 1 for F2, F3, and F4, respectively. For those same stages, APRI scores were 0.854, 0.886, and 0.851; the difference in scoring with the two modalities was statistically significant. Limitations of the study and findings are detailed in the journal article, including inexact correlation between elasticity maps constructed with MR and biopsy findings.
Correct staging of liver fibrosis is critical in disease management and treatment; disease treated too early can result in ill effects which outweigh treatment benefits. Ideally, disease stage should be broken down into three stages: early, intermediate, and advanced fibrosis of the liver.
November 9, 2007 Related topics: Imaging, Diagnostic, Renal & Urology