We read with great interest the recent article by Dr Yao and colleagues entitled “Dual-phase Cone-beam CT-based Navigation Imaging Significantly Enhances Tumor Detectability and Aids Superselective Transarterial Chemoembolization of Liver Cancer” ( ). Dr Yao et al. analyzed the increase of liver nodule detection using Dual Phase Cone Beam Computed Tomography (DP-CBCT) over Digital subtraction angiography (DSA) (100% vs 83%, p < 0.05), on the contrary no differences were highlighted regarding occult nodule detection at non–invasive second line diagnostic modality (computed tomography [CT] or magnetic resonance) (100% vs 96%, p > 0.05). In addition, Dr Yao etal., comparing lipiodol-transarterial chemoembolization performed respectively under DP-CBCT guidance and DSA only procedure, were able to achieve more super-selective embolization (60% vs 49%) with a reduction of fluoroscopy time (4.1 ± 2.6vs 7.1 ± 4.2 minutes, p < .001) and DSA acquisition (2.6 ± 0.8vs 3.4 ± 0.7, p < 0.001) with a minimal increase of radiation dose (dose area product 134, 92–181vs 97, 75–140 Gy•cm 2 , p = .048).
Despite these major advantages in term of radiation dose and mean procedural time reduction, the comparison between the cohorts that underwent treatment under CBCT guidance versus treatment under DSA guidance alone is far to be detailed. In fact, author do not present data regarding the complexity of the procedure (degree of selectivity of the embolization procedure, superselective catheterization via coaxial microcatheter) not even the mean tumor diameter is displayed. In order to really compare the reduction dose, it would be vital to know whether the two cohorts were substantially similar in terms of technical procedural aspects.
Moreover, we are surprised about the poor rate of occult nodule visualization depicted by CBCT imaging over non–invasive second line imaging. In fact, CBCT has been shown to significantly increase lesion detection rate ( ). We are wondering if the injection protocol employed within this series could have significantly impaired the CBCT occult nodule detection rate. Usually, contrast media is administered diluted (1:3) to avoid streaks artefacts and the injection rate is significantly higher (4 mL/second) in nonsegmental branches. Moreover, the timing of the acquisition is crucial ( ). In our center we perform DP-CBCT by injecting for 15 seconds and starting the first acquisition after 8 seconds delay to be able to combine liver parenchyma enhancement with liver vasculature complete mapping. Last but not least, delayed phase imaging is acquired not at 12 seconds but after 30–35seconds from the contrast media administration in order toacquire a “venous” phase allowing lesion characterization (e.g. wash out depiction) ( ).
References
1. Yao X, Yan D, Jiang X, et. al.: Dual-phase cone-beam CT-based navigation imaging significantly enhances tumor detectability and aids superselective transarterial chemoembolization of liver cancer. Acad Radiol 2018; in press
2. Lucatelli P, Argiro R, Ginanni Corradini S, et. al.: Comparison of image qualityand diagnostic performance of cone-beam CT during drug-eluting embolic transarterial chemoembolization and multidetector CT in the detection of hepatocellular carcinoma. J Vasc interventional Radiol: JVIR 2017; 28: pp. 978-986.
3. Lucatelli P, Corona M, Argiro R, et. al.: Impact of 3D rotational angiography on liver embolization procedures: review of technique and applications. Cardiovasc Interventional Radiol 2015; 38: pp. 523-535.
4. Lucatelli P, Argiro R, Levi Sandri GB, et. al.: Single-injection dual-phase cone-beam CT is better than split-bolus single-phase cone-beam CT for liver catheter-based procedures. J Vasc Interv Radiol 2018; 29: pp. 748-749. doi:10.1016/j.jvir.2017.12.026