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Technical Innovation |
1 Department of Internal Medicine, Division of Gastroenterology and Hepatology,
Kinki University School of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama
589-8511, Japan.
2 Department of Surgery, Kinki University School of Medicine, Osaka-Sayama
589-8511, Japan.
Received March 4, 2003;
accepted after revision October 30, 2003.
Address correspondence to M. Kudo.
Introduction
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Recently, it was reported that inducing artificial pleural effusion, which acts as an acoustic window, could solve the first limitation [4]. Moreover, contrast-enhanced harmonic sonography, which depicts tumor vascularity in hepatocellular carcinomas sensitively and accurately [5, 6], could solve the second problem. We examined the feasibility and safety of this new technique, percutaneous radiofrequency ablation guided by contrast-enhanced harmonic sonography with concurrent use of artificial pleural effusion for local recurrences of hepatocellular carcinoma located in the right subphrenic region.
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B-mode sonography scans were obtained using a LOGIQ 700 Expert series unit (General Electric Medical Systems) with a 2-4–MHz curved array wideband transducer.
The patients in this series were treated using a Cool-tip Radiofrequency System (Radionics), which is a 480-kHz generator capable of producing a maximum power of 200 W through a 17-gauge monopolar cooled-tip needle electrode. Each ablation was performed for a period of 12 min, as recommended by the manufacturer.
All patients were sedated consciously via an IV injection of 25 mg of hydroxyzine and 15 mg of pentazocine in a therapeutic sonography room. Patients were placed in the Fowler position, lying on their backs keeping the head up on a slant, and given oxygen at a speed of 2 L/min through a nasal cannula. A needle (Veress, Olympus Optical), used for intraperitoneal infusion of CO2 gas in laparoscopic surgery, was intrathoracically inserted through the chest wall after local anesthesia. A 5% glucose solution was infused intrathoracically to separate the lung and liver until it was possible to obtain an image of the hepatic dome on sonography. The 5% glucose solution was selected because of its lower risk of electric leakage than normal saline.
After the sonographic mode was switched from B-mode to the contrast-enhanced harmonic imaging mode, the sonographic contrast agent SH U 508A (Levovist, Schering) was injected into the antecubital vein. Maintaining a real-time approach by slightly changing the scanning plane, fast low-angle shot imaging was performed of viable tumor parenchymal flow during the vascular phase, which occurred less than 2 min after injection of Levovist. The images of recurring hepatocellular carcinoma lesions were well enhanced by contrast-enhanced harmonic sonography. Thus, enhanced lesions could be targeted for insertion of radiofrequency ablation needles through the diaphragm (Fig. 1A, 1B, 1C, 1D, 1E). On the other hand, repeated injections were required for longer procedures.
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If triple phase dynamic CT identified residual tumor enhancement approximately 1 week later, a second radiofrequency ablation treatment session was performed within 1 week of posttreatment CT assessment.
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Two patients complained of mild dyspnea after treatment. However, these symptoms disappeared after they received oxygen. No lung injuries, such as pneumothorax, were observed in any patients. No patients had empyema, and none used prophylactic antibiotics. It took approximately 1 week for the pleural effusions to spontaneously resolve.
In one patient, tumor recurrence was observed on dynamic CT 1 month after radio-frequency ablation therapy. In the other patients, no recurrence was seen locally in the liver on dynamic CT during the follow-up period (mean, 13 months).
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Both viable lesions and necrotic lesions exhibit a heterogeneous sonography pattern in recurring cases of hepatocellular carcinoma after ablation therapy [1]. Thus, efficiently treating recurring hepatocellular carcinoma lesions after percutaneous ablation is frequently difficult. The success rate of percutaneous ablation depends on the appropriate targeting of imaging techniques. In our study, contrast-enhanced harmonic sonography increased the sensitivity for depicting viable hepatocellular carcinoma foci in 13 (81%) of 16 lesions after artificial pleural effusion. Almost all patients completed the treatments with one session of percutaneous therapy. Thus, contrast-enhanced harmonic sonography guidance may improve the efficiency of radiofrequency ablation for hepatocellular carcinoma nodules that are not clearly depicted by B-mode sonography. On the other hand, percutaneous ablation therapy guided by CT is an effective treatment method under the same conditions [2, 3]. However, CT-guided procedures expose the patient to radiation caused by repeated CT penetration because inserting the radiofrequency needle into a viable lesion on the first attempt is difficult. In cases in which hepatocellular carcinoma nodules located in the deep side by contrast-enhanced harmonic sonography cannot be depicted, CT guidance should be performed.
Our study has limitations. The follow-up time was too short to clarify the possibility of seeding the pleural space with malignant tumor cells in this procedure. Although no cases of seeding were observed, further follow-up and studies may be necessary to clarify the problem of seeding.
In conclusion, percutaneous radiofrequency ablation guided by contrast-enhanced harmonic sonography with artificial pleural effusion is an efficient approach for treatment of locally recurring hepatocellular carcinoma nodules located in the right subphrenic region that are not clearly depicted on B-mode sonography.
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