抄録
Background: The clinical implementation of cardiac 123Iodine-meta-iodobenzylguanidine (123I-MIBG) scintigraphy for the evaluation of prognosis in patients with heart failure (HF) is still limited. This may partially be related to the long examination time with an almost 4 hour delay between the early and late acquisition. Additionally, outcome derived at different late acquisition times cannot be compared with each other. To assess whether earlier acquisition time of the late image is justified, the aim of present study was to evaluate in a HF patient cohort whether a developed direct comparison method for cardiac 123I-MIBG imaging enables comparison of washout rates and late heart-to-mediastinum (H/M) ratios from 1 to 3 hours post injection (pi) with measurements at 4 hours pi.
Methods: Forty-eight patients with HF were clinically referred for cardiac 123I-MIBG scintigraphy. The washout rate and late H/M ratio at 4 hours pi were estimated with a previous published linear model from heart and mediastinal counts at 1, 2 and 3 hour pi and compared with the actual values at 4 hour pi.
Results: The estimated washout rate and late H/M ratio at 4 hours pi from counts at 1 hour pi demonstrated large differences. However, the average estimated late H/M ratio at 4 hours pi derived from 2 and 3 hours pi did not differ with the actual late H/M ratio at 4 hours pi (P=0.84 and P=0.06). As well as, the actual washout rate at 4 hours pi and estimated washout rate at 4 hours pi derived from 3 hours pi did not differ significantly (P=0.22). Yet, the mean estimated washout rate at 4 hours pi derived from the acquisition at 2 hours pi showed a difference compared with the actual washout rate at 4 hours pi (25±19 vs. 34±17, P<0.001).
Conclusions: The direct comparison method for cardiac 123I-MIBG imaging enables accurate estimation of the actual late H/M ratio and washout rate at 4 hours pi derived from the acquisitions at 3 hours pi. The acquisition at 2 hours pi should only be performed in exceptional cases when clinically necessary because of the existing difference between the actual and estimated washout rate at 4 hours pi derived from 2 hours pi.
