MAGNETIC-RESONANCE-IMAGING AND HEPATIC HEMODYNAMICS - CORRELATION WITH METABOLIC FUNCTION IN LIVER-TRANSPLANTATION CANDIDATES

Background. Preoperative assessment of orthotopic liver transplantatio n candidates requires definition of both the anatomy and metabolic fun ction of the native liver. Current evaluation techniques combine compu ted tomographic scanning, duplex ultrasonography with blood chemistry analysis, and physical stigmata of end-stage liver disease. Recently, magnetic resonance imaging (MRI) has emerged as an alternative method for delineation of hepatic and portal venous anatomy. In addition, MRI accurately measures hepatic volume and portal venous blood flow. Meth ods. To examine the role of MRI-derived indexes of hepatic hemodynamic s in the preoperative assessment of liver function, 39 consecutive liv er transplantation candidates were studied in a prospective manner. Li ver function (aspartate aminotransferase), alanine aminotransferase, a lkaline phosphatase, total bilirubin, and albumin levels), hematologic indexes (complete blood cell count, prothrombin time), and Child's cl assification were determined at the time of evaluation. Axial breath-h eld multiplanar spoiled-gradient echo MRI measured hepatic volume, whe reas a cine phase-contrast sequence perpendicular to the portal vein m easured flow. Results. Hepatic index, defined as hepatic mass correcte d for body surface area, was found to correlate with prothrombin time (p < 0.04) and platelet count (p < 0.03) by multivariate regression an alysis. Portal flow index (PFI), defined as portal flow corrected for hepatic mass), was associated with aspartate aminotransferase (p < 0.0 2), alanine aminotransferase (p < 0.04), and albumin (p < 0.03) by mul tivariate regression analysis. In addition, PFI was closely correlated with the patients' functional status as determined by Child's classif ication system. Increasing values of PFI were associated with declinin g hepatic functional reserve. Child's class A patients had a mean PFI that was two times less than that of Child's class B patient (0.26 +/- 0.04 versus 0.46 +/- 0.06 ml/min/gm; p < 0.02) and five times less th an that of Child's class C patients (0.26 +/- 0.04 versus 1.05 +/- 0.1 4 ml/min/gm; p < 0.01). Similarly, the mean PFI associated with Child' s class B was two times less than that of Child's class C (0.46 +/- 0. 06 versus 1.05 +/- 0.14 ml/min/gm; p < 0.01). These data show that MRI -derived indexes of portal hemodynamics and hepatic mass (1) correlate d well with biochemical indexes of hepatic dysfunction and (2) serve a s anatomic and hemodynamic correlates to Child's functional classifica tion. Conclusions. We conclude that MRI may serve to noninvasively del ineate preoperative hepatic vascular anatomy and metabolic dysfunction in candidates undergoing examination for liver transplantation.