Which continuous US scanning mode is optimal for the detection of vascularity in liver lesions when enhanced with a second generation contrast agent?
OBJECTIVE
Microbubble echo-enhancers help in the assessment of focal liver masses by enhancing the signal from blood vessels. A variety of linear and nonlinear scanning modes are now available, but it is unclear which is optimal. A controlled comparison was performed during the infusion of such an agent (SonoVue: Bracco, Milan, Italy).


METHODS
Ten patients with known focal liver lesions were studied. The diagnoses, confirmed on dual phase helical computed tomography (CT) at the same attendance were metastasis (n = 7), haemangioma (n = 2) and focal nodular hyperplasia FNH (n = 1). A dose of 12 ml SonoVue concentrated at 5 mg/ml was infused intravenously at a rate of 1 ml/min. The enhancement level was monitored with a continuous wave (CW) Doppler probe over the right radial artery and the intensity of the signal was registered at 1 s intervals. When a plateau of enhancement was reached, a single lesion in each patient was imaged using five different continuous scanning modes, fundamental grey scale (FGS); fundamental colour Doppler (FCD); fundamental power Doppler (FPD); second harmonic grey scale (HGS); and pulse inversion mode (Pim) using an HDI5000 scanner and C5-2 probe (ATL, Bothell, WA). The order of scanning modes was varied between patients using a predefined randomisation protocol. The videos (super video home system (SVHS)) were analysed offsite by two blinded readers, both experienced in contrast ultrasound of the liver. The readers were asked to score each mode in terms of its ability to detect vessels within/around the lesion at optimal enhancement. This was done using a ranking system (1, worst; 5, best) for each patient.


RESULTS
Both observers scored FPD as the optimal imaging method, followed by Pim. (Scores summed across all patients, observer 1: FPD 48, Pim 42, FCD 37, HGS 21, FGS 10; observer 2: FPD 49, Pim 40, FCD 38, HGS 21, FGS 10). The differences from FPD were significant for FCD, HGS and FGS using a unpaired analysis of variance (ANOVA) comparison, with Bonferroni multiple corrections, (P<0.01, both observers). The differences between FPD and Pim were also significant both for observer 2 and for both observers combined (P<0.01), but did not reach significance for observer 1 (P = 0.19).


CONCLUSIONS
In this study, FPD performed best, and the non-linear modes, performed continuously (pulse inversion and second HGS), showed no clear advantage.
Basilico
Raffaella
R
Department of Radiology, University of Chieti, Policlinico SS Annunziata, Via dei Vestini, 66013 Chieti, Italy. r.basilico@radiol.unich.it
Blomley
Martin J K
MJ
Harvey
Christopher J
CJ
Filippone
Antonella
A
Heckemann
Rolf A
RA
Eckersley
Robert J
RJ
Cosgrove
David O
DO
D000328:Adult; D000368:Aged; D003287:Contrast Media; D006801:Humans; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000556:secondary; D008875:Middle Aged; D010743:Phospholipids; D013459:Sulfur Hexafluoride; D018608:Ultrasonography, Doppler / Q000379:methods
D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride