Confirming the normal range for Mebrofenin liver function indices

To establish normal ranges for [^99mTc] Tc-Mebrofenin hepatobiliary scintigraphy (HBS) indices of liver function and the associated uncertainty in clinical measures due to region placement.

47 patients referred for gallbladder assessment with no history of liver disease were included in the study. Patients underwent dynamic HBS following injection of 200 MBq of [^99mTc] Tc-Mebrofenin at 10 seconds/frame for 36 frames. Analysis was performed by 5 experienced technologists using in-house software (MIM Software, Cleveland, Ohio) to establish blood pool (BP) clearance rate (%/min), blood clearance half-time (min), mebrofenin liver uptake rate (MUR) (%/min) and MUR normalised to body-surface-area (MUR_BSA) (%/min/m²). Limits of normal ranges (95%) were established and correlation of functional indices with age was investigated. Analysis was repeated after a minimum of 4 weeks to establish intra-user variability and uncertainty associated with measures.

Data were collected for 27 women and 20 men, with an age range of 20 - 81 years. Twenty-seven patients were aged over 50 and 20 patients were aged below 50. The data were found to have a normal distribution. The mean values derived for the entire cohort for BP clearance rate, blood clearance half time, MUR, and MUR_BSA were 16.8±2.6 %/min, 4.3±0.7 min, 14.4±2.0 %/min and 8.0±1.5 %/min/m², respectively. No significant difference in values was found between age groups and no correlation between liver function and age was found. The lower range of normal for MUR_BSA was established as 5.1%/min/m², with clinical measures expected to have an uncertainty of ±0. 6 %/min/m².

The MUR_BSA value for a patient with normal liver function can be expected to be approximately 8.0±1.5 %/min/m², with a lower limit of normal function at 5.1 %/min/m². Patients receiving liver surgery or treatment that express MUR_BSA values below this may be at higher risk and should potentially be treated with caution.