Correction


In the article entitled “Brain metabolism of 13N-ammonia during acute hepatic encephalopathy in cirrhosis measured by positron emission tomography” by Keiding et al. (HEPATOLOGY 2006;43:42-50), there was an arithmetical error in the calculations of PSBBB in Table 2. The Table below gives corrected values. Since the PSBBB calculation is based on individual values of cerebral blood flow, CBF, and the initial unidirectional clearance of 13N-ammonia, K1 as PSBBB = -CBF ln(1-K1/CBF), mean values of CBF and K1 now include only individuals where both CBF and K1 were measured. Mean PSBBB values in the group of patients with cirrhosis and HE were lower than mean values in the group of healthy controls but the difference was not statistically significant.

Table 2. Regional Cerebral Blood Flow and 13N-Ammonia Kinetic Parameters in Cirrhotic Patients With and Without an Acute Episode of HE and in Healthy Controls
  CBFK1PSBBBKmetPSmetMetabolic flux
mL blood/ min/mL tissuemL blood/ min/mL tissuemL blood/ min/mL tissuemL blood/ min/mL tissuemL blood/ min/mL tissueμmol ammonia/ min/L tissue
  • NOTE. Values are given as mean ± standard error of the mean; n, number of subjects. The * and ** indicate that the mean is statistically significantly different from the corresponding regional value in healthy control group:

  • *

    P < .05;

  • **

    P < .01.

  • CBF, cerebral blood flow, was determined from dynamic 15O-water PET. Dynamic 13N-ammonia PET estimates: K1, initial clearance of 13N-ammonia across blood-brain barrier (BBB) from blood to cells; PSBBB, blood-brain permeability for 13N-ammonia; Kmet, net metabolic clearance of 13N-ammonia in blood to intracellular 13N-metabolites (mainly 13N-glutamine). Metabolic flux of ammonia from blood into brain tissue was calculated as Kmet multiplied by arterial ammonia concentration.

Cirrhosis with HECortex0.38 ± 0.030.23 ± 0.010.37 ± 0.030.15 ± 0.010.20 ± 0.0113.4 ± 0.9**
 Basal ganglia0.56 ± 0.040.31 ± 0.020.43 ± 0.030.21 ± 0.010.27 ± 0.0118.2 ± 1.2**
 Cerebellum0.52 ± 0.050.26 ± 0.020.37 ± 0.020.19 ± 0.010.24 ± 0.0116.7 ± 1.3**
(n) 666888
Cirrhosis without HECortex0.44 ± 0.060.26 ± 0.020.42 ± 0.070.20 ± 0.03*0.23 ± 0.047.4 ± 1.4**
 Basal ganglia0.59 ± 0.050.36 ± 0.020.59 ± 0.070.27 ± 0.04*0.32 ± 0.0410.6 ± 2.0**
 Cerebellum0.59 ± 0.070.30 ± 0.030.44 ± 0.070.24 ± 0.030.27 ± 0.038.8 ± 1.6**
(n) 555777
Healthy ControlsCortex0.47 ± 0.030.29 ± 0.030.46 ± 0.080.16 ± 0.010.20 ± 0.012.6 ± 0.3
 Basal ganglia0.62 ± 0.050.31 ± 0.010.45 ± 0.020.21 ± 0.010.26 ± 0.023.4 ± 0.3
 Cerebellum0.64 ± 0.040.30 ± 0.020.41 ± 0.040.19 ± 0.010.23 ± 0.013.1 ± 0.4
(n) 555555

Ancillary