Portal blood flow: measurement with MR imaging.

Abstract

Portal blood flow was measured by means of direct bolus imaging (DBI), a method of measuring flow velocity with magnetic resonance imaging. DBI allows immediate visualization of fluid movement, thereby enabling calculation of a flow velocity from fluid displacement. In a study of 14 healthy male volunteers, portal blood flow was measured with electrocardiographic gating during the 18 seconds subjects could suspend respiration. These measurements showed a close correlation (r = .968) with those obtained by means of Doppler ultrasound (US). Increases in portal blood flow after oral administration of ethanol and glucose were measured with DBI. Glucose caused a statistically greater increase in portal blood flow volume in healthy control subjects than in patients with chronic hepatitis. Blood sugar, on the other hand, showed a significantly greater increase in these patients, possibly reflecting the greater vascular resistance of the liver. DBI is a useful noninvasive method of measuring portal blood flow without the limitations imposed on Doppler US by obesity and intestinal gas.

Portal venous blood flow while breath-holding after inspiration or expiration and during normal respiration in controls and cirrhotics

“…[4][5][6][7][8][9] In healthy subjects, Burkart et al 7 and Lycklama à Nijeholt et al 8 measured mean blood flow in the main portal vein and found a rate of 1.2 l/min under basal fasting conditions during normal respiration. In our previous 9 and present studies, mean blood flow in the main portal vein under fasting conditions in the healthy controls during normal during normal respiration was 1.3 l/ min, showing good agreement for results in healthy subjects.…”

“…More recent studies have demonstrated that a cine phase-contrast magnetic resonance (MR) velocity mapping method can noninvasively measure quantitative blood flow in the portal venous system throughout the cardiac cycle during normal respiration. [4][5][6][7][8][9] In this study, we investigated changes in flow velocity and flow volume in the main portal vein under basal fasting conditions while subjects were breath-holding after maximal inspiration or expiration, and compared this with portal blood flow during normal respiration. Blood flow measurements using MR imaging were made in healthy controls and portal hypertensive cirrhotics and the results were compared.…”

Hypoglycemic Detection at the Portal Vein

“…A number of sophisticated modeling approaches employing multiple tracers have been developed for estimating the appearance of an oral glucose load (15,16) but, to date, have not been used in studies of portal glucose sensing in humans. Further confounding estimates of portal glucose concentration is the wide range of values reported for human portal blood flow, (10 -18 ml ⅐ kg Ϫ1 ⅐ min Ϫ1 [17]), which may increase substantially in response to oral glucose ingestion.…”

Oesophageal varices: Assessment of the risk of bleeding and mortality

“…Magnetic resonance (MR) imaging, by means of time‐of‐flight or phase contrast angiography, can document the size and direction of the flow in a vessel, in a similar way to Doppler ultrasound examination. 52 This is an easy method for the detection of spontaneous portosystemic collaterals. Quantification can be obtained by Cine‐Phase Contrast flow measurements.…”