Exploring the role of ^99mTc-Mebrofenin in both pre- and post-radioembolisation evaluation of liver function

Aim: To explore the role of ^99mTc-Mebrofenin in both pre-treatment guidance of radioembolisation (RE) prescribing based on regional liver function, as well as post-treatment monitoring of radiation dose effects.

Methods: 35 subjects receiving RE (SIR-Spheres, Sirtex Medical, AUS) for treatment of liver disease (15 from colorectal primary) underwent imaging with the agent ^99mTc-Mebrofenin to evaluate hepatocyte function both immediately before and approximately 8 weeks after RE. Imaging consisted of a 6 min planar dynamic study used to evaluate liver uptake rate as well as fast SPECT/CT. The baseline and follow-up liver uptake rate and blood clearance rate were measured using a Patlak-Rutland analysis, and compared to absorbed dose measures derived from post-RE PET imaging (average dose to normal liver, minimum dose to 70% of normal liver (D70), and volume of normal liver receiving at least 50 Gy (V50)).

Results: No significant correlation could be found between change in hepatocyte function as measured by Mebrofenin with either normal liver average dose or V50; a correlation was found with D70. A negative correlation was found between change in liver uptake rate and baseline liver uptake rate, suggesting that the hepatocyte function reflected in Mebrofenin studies may not be indicative of a candidate’s suitability for treatment, or guidance of prescribing thereof. Both D70 and baseline uptake rate (negative) could predict a significant (>25%) drop in liver uptake rate post-therapy (p=0.024, p=0.022, respectively).

Conclusions: The role of ^99mTc-Mebrofenin in guidance and evaluation of RE is still uncertain, however this study suggests that D70 may be more indicative than either average dose or V50 in of damage to healthy liver parenchyma.