Ultrasound Pressure Estimation for Diagnosing Portal Hypertension in Patients Undergoing Dialysis for Chronic Kidney Disease.

Abstract

Hepatic venous pressure gradient (HVPG) is considered the standard in quantifying portal hypertension, but can be unreliable in dialysis patients. A noninvasive ultrasound technique, subharmonic-aided pressure estimation (SHAPE), may be a valuable surrogate of these pressure estimates. This study compared SHAPE and HVPG with pathology findings for fibrosis in dialysis patients. This was a subgroup study from an IRB-approved trial that included 20 patients on dialysis undergoing SHAPE examinations of portal and hepatic veins using a modified Logiq 9 scanner (GE, Waukesha, WI), during infusion of Sonazoid (GE Healthcare, Oslo, Norway). SHAPE was compared to HVPG and pathology findings using the Ludwig-Batts scoring system for fibrosis. Logistic regression, ROC analysis, and t-tests were used to compare HVPG and SHAPE with pathological findings of fibrosis. Of 20 cases, 5 had HVPG values corresponding to subclinical and clinical portal hypertension (≥6 and ≥10 mmHg, respectively) while 15 had normal HVPG values (≤5 mmHg). SHAPE and HVPG correlated moderately (r = 0.45; P = .047). SHAPE showed a trend toward correlating with fibrosis (r = 0.42; P = .068), while HVPG did not (r = 0.18; P = .45). SHAPE could differentiate between mild (stage 0-1) and moderate to severe (stage 2-4) fibrosis (-10.4 ± 4.9dB versus -5.4 ± 3.2dB; P = .035), HVPG could not (3.0 ± 0.6 mmHg versus 4.8 ± 0.7 mmHg; P = .30). ROC curves showed a diagnostic accuracy for SHAPE of 80%, while HVPG reached 76%. Liver fibrosis staging in dialysis patients evaluated for portal hypertension appears to be more accurately predicted by SHAPE than by HVPG; albeit in a small sample size.