Agitated saline with 10% blood increases number and stability of microbubbles in detection right-to-left shunt by contrast-enhanced transcranial Doppler: an in vitro and in vivo observational study

Abstract

Background Agitated saline (AS) with blood has been shown to have good tolerance and increased efficacy when used in contrast-enhanced transcranial Doppler (c-TCD) to detect right-to-left shunt (RLS). However, little is known about the effects of blood volume on c-TCD results. Our study investigated the characterization of AS with different blood volumes in vitro and compared the c-TCD results in vivo . Methods In vitro , AS without blood, AS with 5% blood (5% BAS), and AS with 10% blood (10% BAS) were prepared based on previous studies and observed under microscopy. The numbers and sizes of the microbubbles from different contrast agents were compared immediately, 5 min, and 10 min post-agitation. In vivo , 74 patients were recruited. c-TCD was repeated 3 times using AS with different blood volumes in each patient. Signal detection times, positive rates, and classifications of RLS were compared among the 3 groups. Results In vitro , the AS without blood produced 5.4±2.4/field microbubbles after agitation, the 5% BAS produced 30.4±4.2/field, and the 10% BAS produced 43.9±12.7/field. More microbubbles remained in the 10% BAS than the 5% BAS within 10 min (18.5±6.1 vs. 7.1±2.0/field, P<0.001). The size of the microbubbles from the 5% BAS increased from 9.2±8.2 to 22.1±10.6 µm within 10 min post-agitation (P=0.014), while the 10% BAS changed insignificantly. In vivo , the signal detection times of the 5% BAS (1.1±0.7 s) and 10% BAS (1.0±0.8 s) were significantly shorter than the AS without blood (4.0±1.5 s, P<0.0001). The RLS positive rates were 63.5%, 67.6% and 71.6% in AS without blood, 5% BAS and 10% BAS respectively; however, the differences were not statistically significant. The AS without blood reached 12.2% level III RLS, while the 5% BAS reached 25.7%, and the 10% BAS reached 35.1% (P=0.005). Conclusions The 10% BAS would be suggested in c-TCD as it addressed larger RLS by increasing the number and stability of microbubbles, and it improves the diagnosis of patent foramen ovale (PFO).

Diagnostic value of contrast-enhanced ultrasonography for patent foramen ovale detection

“…Recently, an in vitro and in vivo observational study showed that agitated saline with 10% blood increases number and stability of MBs in detection RLS by contrast enhanced transcranial Doppler. And it showed that both the size and number of MBs were most stable in the agitated saline (AS) with 10% blood (10% BAS), which could be the reasons why the 10% BAS had the highest positive rate and RLS levels in cTCD ( 28 ). Our study also showed good repeatability of cTCD with 10% BAS.…”