Estimation of gallbladder ejection fraction utilizing cholecystokinin-stimulated magnetic resonance cholangiography and comparison with hepatobiliary scintigraphy.

PURPOSE

To evaluate the utility of magnetic resonance cholangiography (MRC) in estimation of gallbladder ejection fraction (GBEF) and to comparing this value to the conventional method, hepatobiliary scintigraphy (HBS).

MATERIALS AND METHODS

Twenty-one healthy volunteers were imaged on sequential weeks to determine GBEF using MRC and HBS. GBEF was calculated by HBS after infusion of 20 ng/kg of sincalide following injection of 111 Mbq of Tc 99(m) mebrofenin. For estimation by MRC, imaging of the gallbladder was performed before and after slow infusion of sincalide every 5 minutes, for a total of 60 minutes. Gallbladder imaging was performed using a heavily T2-weighted 2D fast spin echo (FSE) sequence. Data was analyzed using a variance component analysis technique.

RESULTS

Mean GBEF by HBS was 65.7%, with an SD of +/-27.3%. Mean GBEF by MRC was 62.7%, with an SD of +/- 20.4%. If minimum normal GBEF is set at 35%, two of the cases showed discordance, with HBS calculating an abnormally low average GBEF compared to MRC. Additionally, two cases showed abnormally low GBEF for both modalities. The coefficient of correlation between HBS and MRC was 0.72. Inter- and intraobserver variance is acceptable within the two modalities with <1.1% variation.

CONCLUSION

GBEF can be calculated with MRC, yielding similar values when a group of volunteers are considered. Further study with symptomatic patients is needed to determine the validity of this technique for clinical diagnosis.