Percutaneous radiofrequency ablation for the hepatocellular carcinoma abutting the diaphragm: assessment of safety and therapeutic efficacy

Abstract

Objective: To assess the safety and therapeutic efficacy of a percutaneous radiofrequency (RF) ablation for the hepatocellular carcinoma (HCC) abutting the diaphragm.

Materials and methods: We retrospectively assessed 80 patients who underwent a percutaneous RF ablation for a single nodular (< 4 cm) HCC over the last four years. Each patient underwent an ultrasound-guided RF ablation using internally cooled electrodes for the first-line treatment. We divided patients into two subgroups based on whether the index tumor was abutting (less than 5 mm) the diaphragm or not: group A (abutting; n = 31) versus group B (non-abutting; n = 49). We compared the two subgroups for complications and therapeutic efficacy using image and the review of medical records. The statistical assessment included an independent t-test, Fisher's exact test, and chi-square test.

Results: The assessment of the diaphragmatic swelling at CT immediately following the procedure was more severe in group A than group B (mean thickness change:1.44 vs. 0.46 mm, p = 0.00). Further, right shoulder pain was more common in group A than B (p = 0.01). Although minor complications (hemothorax 1 case, pleural effusion 1 case) were noted only in group A, no major thoracic complication occurred in either group. The technical success rate was lower in group A than group B (84% vs. 98%, p = 0.03). As well, the primary and secondary technique effectiveness rates in group A and group B were 90% versus 98% (p = 0.29) and 79% versus 91% (p = 0.25), respectively. The local tumor progression rate was higher in group A than in group B (29% vs. 6%, p = 0.02).

Conclusion: We found that the percutaneous RF ablation for the HCC abutting the diaphragm is a safe procedure without major complications. However, it is less effective with regard to technical success and local tumor control.

Fig. 1

Comparison of diaphragm thickness between abutting group A and non-abutting group B. Graph shows changes in diaphragmatic thickness in two groups after radiofrequency ablation. Mean increase in diaphragmatic thickness between pre- and immediately after radiofrequency ablation on CT scanning was 1.44 mm for abutting group A and 0.46 mm for non-abutting group B. This difference was statistically significant (p < 0.01). Diaphragmatic thickness spontaneously decreased over time.

Fig. 2

76-year-old man with hepatocellular carcinoma showing diaphragm swelling and enhancement. A. Portal phase CT scan obtained prior to radiofrequency ablation shows enhancing nodule (black arrow) in segment VIII. White line = diameter of diaphragm thickness. B. Portal phase CT scan obtained immediately after radiofrequency ablation shows ablation zone (A) with minimal amount of fluid collection. Swelling and enhancement of diaphragm is noted as thermal injury for abutting ablation zone (white arrow). White line = diameter of diaphragm thickness.

Fig. 3

67-year-old man with hepatocellular carcinoma showing incomplete ablation and hemothorax. A. Arterial phase CT scan obtained immediately after first session of radiofrequency ablation shows residual enhancing lesion (white arrow) at central portion of index tumor. B. Second radiofrequency ablation session of residual tumor was performed on next day. However, persistent enhancing viable portion at ablation margin is noted immediately after radiofrequency ablation (white arrow). Hemothorax (H) at right lung is associated with diaphragmatic thermal injury. At that time, patient's vital signs were stable and resulted in use of conservative treatments only.

Fig. 4

69-year-old man with hepatocellular carcinoma showing transient lung injury. A. Arterial phase CT scan obtained prior to radiofrequency ablation shows enhancing nodule abutting diaphragm in liver segment VII (black arrow). B. In lung window setting obtained immediately after radiofrequency ablation indicated abnormal parenchymal density at right lower lobe (white arrow). Patient was asymptomatic at time. C. Without any specific treatment, lesion resolved at one month follow-up CT scan.

Fig. 5

Flow diagram showing primary and secondary technique effectiveness rates in this study. At one month follow-up CT, primary technique effectiveness rates was 90% (28/31) in group A, compared to 98% (48/49) in group B (p = 0.29). Among 80 patients, secondary technique effectiveness rates was evaluated in 59 patients who had one year or more of follow-up with CT. Secondary technique effectiveness rates was 79% (19/24) in group A, compared to 91% (32/35) in group B (p = 0.25). Both primary and secondary technique effectiveness rates showed no statistically measurable difference. Group A = abutting diaphragm, group B = non-abutting diaphragm