Objective(s): 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.
Methods: 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.
Results: 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.
Conclusion: 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.