Prone transradial approach for radiofrequency ablation of hepatocellular carcinoma in the caudate lobe following TACE: a technical case report

Introduction

Hepatocellular carcinoma (HCC) located in the caudate lobe is technically challenging and often considered unsafe to treat with radiofrequency ablation (RFA) because of its deep location and proximity to major vascular structures.^1,2 Previous studies have reported that HCCs in the caudate lobe have up to five times higher local recurrence rates compared with tumors in other hepatic segments. ¹ This can be attributed to the heat-sink effect caused by large vessels such as the inferior vena cava and to the difficulty in obtaining an optimal puncture route because the tumor is surrounded by vessels.

Combined RFA and transcatheter arterial chemoembolization (TACE) is an established strategy for HCC.^1,2 This approach mitigates the heat-sink effect, but when the tumor is encased by portal veins, establishing an appropriate puncture path remains problematic, which may lead to incomplete ablation.

In the present case, we initially attempted RFA combined with TACE in the supine position for a caudate lobe HCC, but a safe puncture route could not be obtained. We therefore performed angiography in the prone position using a left transradial approach, which has previously been reported in procedures involving extrahepatic organs.^3–5 By combining this approach with the creation of an artificial pneumothorax, safe and complete ablation was achieved. The details of this technique are described below.

Case description/technique

A 71-year-old woman with a history of steatohepatitis and compensated liver cirrhosis (Child–Pugh class A) was diagnosed with a 2-cm HCC in segment I (caudate lobe) of the liver. The lesion was identified on contrast-enhanced computed tomography (CT), showing arterial-phase hyperenhancement and delayed washout, consistent with HCC.

The tumor was not visualized on ultrasonography due to its deep location. A combined procedure of CT-guided percutaneous RFA immediately following conventional TACE was planned, using the femoral arterial approach with the patient in the supine position. However, CT arterial portography (CTAP) revealed no safe percutaneous route owing to the surrounding vascular structures (Fig. 1(a)).OPEN IN VIEWER

It was considered that prone positioning might provide a feasible puncture path. Because a transradial device was not prepared at that time, only conventional TACE was performed on that day via the femoral artery using a mixture of lipiodol and epirubicin (total 2.3 mg).

On the following day, the superior mesenteric artery (SMA) was selectively catheterized for CTAP in the prone position using the left transradial approach with a 5-Fr Glidesheath Slender (Terumo, Japan) (Fig. 2(a)). CTAP confirmed a safe posterior puncture route avoiding major vessels (Fig. 3(a)). Artificial pneumothorax was created using the following method. Under CT guidance, an 18-G needle with a blunted tip was advanced to the pleural surface. After confirming its position, small amounts of air were gradually introduced while slightly advancing the needle, and pneumothorax formation was verified on CT. Subsequently, a VIVA radiofrequency electrode (STARmed, Goyang, South Korea) was inserted percutaneously from the dorsal side under CT guidance using angio-CT system (Canon, Tochigi, Japan), targeting the lipiodol-stained tumor (Figs. 2(b), 3(b) and 3(c)). RFA was performed using a 2.5-cm active tip.OPEN IN VIEWER

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Fig 3.

Puncture performed under computed tomography (CT) guidance. (a) Planning of puncture route for ablation based on CT during arterial portography with the patient in the prone position (arrow: target lipiodol). (b) Puncture performed under CT guidance using artificial pneumothorax with the patient in the prone position (arrow: target lipiodol). (c) Same image as shown in Fig. 3(b), in the lung window. (d) CT obtained at 9 months after the procedure.

After ablation, the celiac artery and common hepatic artery (CHA) were selectively catheterized to confirm the absence of arterial bleeding or arterioportal shunting on digital subtraction angiography. Air in the thoracic cavity was aspirated as much as possible. All procedures were performed by an interventional radiologist (R.S) with 10 years of experience in interventional oncology.

The procedure was completed without complications, as confirmed by post-procedural CT on the following day. The patient was discharged uneventfully. Follow-up imaging at 9 months demonstrated complete tumor necrosis with no evidence of local recurrence (Fig. 3(d)).

Discussion

RFA for HCC located in the caudate lobe is technically challenging because the tumor is deeply situated and surrounded by major vessels. In this case, the portal vein coursed over the tumor from its ventral to lateral aspect. Tilting the patient’s body alone did not allow for a puncture path that avoided the portal vein; therefore, the prone position was selected.

In the prone position, catheter manipulation through the femoral artery would have been difficult, and repositioning from supine to prone would have compromised the sterile field. Consequently, a transradial arterial approach was employed. Prone transradial access has previously been reported for intraoperative angiography during neurosurgical procedures^6,7 and for combined embolization and ablation therapy for retroperitoneal tumors, such as those of the pelvis or kidney,^3–5 but, to our knowledge, has not been reported for hepatic tumors.

This technique may be particularly useful when a dorsal puncture is required for RFA combined with TACE, as in lesions of the caudate lobe or posterior hepatic segments. However, because the puncture path usually traverses the lung, creation of an artificial pneumothorax is often necessary to ensure a safe approach.

Recent studies have also described RFA guided by CT hepatic arteriography (CTHA). ⁸ The present approach may be applicable in cases where conventional supine positioning does not provide a feasible puncture route, thereby offering an alternative for technically challenging ablations.

This report has several limitations that should be noted. It describes a single case with a follow-up period of only 9 months, and therefore, adequate ablation margins and long-term local control remain uncertain. Furthermore, because TACE and RFA were not performed in the same session, the feasibility of performing effective TACE in the prone position is still unknown. In this case, the SMA and CHA were successfully catheterized in the prone position, similar to standard supine procedures. Therefore, catheter manipulation itself appears feasible. However, whether TACE can achieve drug delivery equivalent to that in the supine position remains uncertain and requires further accumulation of cases.

Nevertheless, this case illustrates that modifying the patient’s position and access route can expand treatment options by enabling safe puncture even when standard approaches are not possible.

In conclusion, this case demonstrates that the prone position using radial arterial approach can be an effective alternative for performing RFA combined with TACE in patients with difficult-to-access posterior hepatic tumors. With careful patient selection and procedural planning, this approach may expand the technical possibilities of interventional oncology for liver tumors.