Purpose: To reveal the mechanism of dense accumulation of lipiodol emulsion (LE) in hepatocellular carcinoma (HCC) during selective balloon-occluded transarterial chemoembolization (B-TACE).
Methods: Balloon-occluded arterial stump pressure (BOASP) at the embolization portion was measured during selective B-TACE for 43 nodules in 42 patients. Fluoroscopy and digital subtraction angiography were prospectively observed during selective B-TACE to note whether dense LE accumulation in HCC occurred. The LE concentration ratio of HCC to embolized liver parenchyma (LECHL ratio) was also calculated for each treatment on the basis of the computed tomographic scan obtained immediately after selective B-TACE. The relationships between degree of LE accumulation and the BOASP, as well as the LECHL ratio, were analyzed.
Results: Arterial flow beyond the catheter tip was maintained even after balloon inflation. In 39 of 43 treatments, LE inflow into the nontumorous liver parenchyma ceased immediately after LE droplets were filled in arteries of the nontumorous liver parenchyma while LE inflow into the HCC nodule continued (group 1). More dense LE accumulation in HCC nodule was obtained in these 39 treatments. In four treatments, LE inflow both into the nontumorous liver parenchyma and into the HCC nodule continued, and no dense LE accumulation in HCC nodule was observed (group 2). In these four treatments, thick anastomotic vessels with collateral artery were noted. The BOASP in group 1 was (mean ± SD) 33.8 ± 12.8 mmHg (range 13-64 mmHg) and that in group 2 was 92.3 ± 7.4 mmHg (range 83-100 mmHg). There was a statistically significant difference in BOASP between groups (p = 0.00004, Welch's t test). The LECHL ratio in group 1 was 18.3 ± 13.9 (range 2.9-54.2) and that in group 2 was 2.6 ± 1.1 (range 1.7-4.2). There was a statistically significant difference in the LECHL ratio between the groups (p = 0.000034, Welch's t test).
Conclusion: Selective B-TACE induced dense LE accumulation in HCC nodules in 39 (91 %) of 43 treatments in which BOASP was 64 mmHg or less.