Nonthermal Ablation of Liver Lesions

Indications

The primary indication for PES is patients with symptomatic simple liver cysts. It is also a therapeutic option for patients with polycystic liver disease. Crucial to management is distinguishing between a simple cyst, a mucinous cystic neoplasm, an echinococcal cyst, and other primary and metastatic tumors. On ultrasound (US), a simple cyst appears as an anechoic unilocular fluid-filled collection with imperceptible walls and posterior acoustic enhancement. On CT and magnetic resonance imaging (MRI), a simple cyst appears as a well-defined water-attenuation lesion with no enhancement on postcontrast images ( Fig. e99.1 ). In the setting of an indeterminate lesion or hemorrhage into a simple cyst, definitive identification with MRI can generally be obtained. If there is uncertainty that a discovered cyst is the cause of the patient’s pain, a trial of simple aspiration can be performed, with ethanol sclerosis performed in the setting of symptomatic cyst recurrence.

Contraindications

Contraindications to hepatic cyst aspiration with PES include cyst communication with the biliary system, communication with the peritoneal cavity, and irreversible coagulopathy. Injection of sclerosants in the presence of biliary communication can result in sclerosing cholangitis. An international normalized ratio of less than 1.5 and an absolute platelet count greater than 50,000 have shown to decrease complication rates.

Equipment

The equipment necessary to perform hepatic cyst PES includes an ultrasound machine with a 3- to 5-MHz curved array transducer, an 18-gauge needle, a 0.035-inch Amplatz wire, appropriate fascial dilators, a 6F–12F multipurpose drainage catheter, and a sterile tray and sheets. A sterile solution of ethanol (95%– 99%) by volume is also prepared. The procedure should be performed in a fluoroscopy suite or on a CT scanner to evaluate for communication of cyst to biliary system or peritoneal cavity.

Technique

The procedure is performed with a combination of local anesthesia (1% lidocaine) and conscious intravenous sedation utilizing a sterile technique, with real-time image guidance. Prophylactic antibiotics are not routinely administered.

Local 1% lidocaine is administered at the determined puncture site before gaining access to the cyst via an 18-gauge needle. After access to the cyst, a fluid sample (∼20 mL) is sent for cytologic examination to exclude malignancy or infection. An 0.035-inch Amplatz wire is then placed through the needle into the cyst, with the needle then withdrawn and a 6F–12F multipurpose drainage catheter with side holes advanced into the cyst after appropriate fascial dilation. All fluid is then aspirated from the cyst, with complete drainage confirmed via imaging. After complete evacuation of the cyst, dilute water-soluble contrast (half the amount of aspirated volume) is then injected under fluoroscopy or CT guidance to evaluate for communication between the cyst and the biliary tree or peritoneal cavity. The procedure is aborted if a communication is present. In the absence of a communication, the contrast material is removed before instillation of sterile ethanol. The volume of ethanol instilled is generally selected to be between 25% and 40% of the volume of cyst fluid aspirated. The drainage catheter is then capped, and the ethanol is left in place for 20–30 minutes, with the patient rolled into various positions to ensure treatment of all surfaces of the cyst cavity. Alcohol should be in contact with the whole cyst cavity during the treatment to fix the epithelial cells and disable their ability to secrete fluid. The ethanol is then aspirated, with the volume removed generally found to be greater than the volume injected because of the release of loculated pockets of fluid or dead cells. This procedure may be repeated in the setting of large cysts (generally >400 mL). The catheter is then removed and the skin bandaged.

A study that compared single-session ethanol sclerotherapy to prolonged catheter drainage with negative pressure demonstrated similar results between the two methods, with statistically insignificant differences in regard to average cyst volume reduction, final cyst volume, or cyst disappearance rates.

Controversies

The primary controversy surrounding hepatic cyst PES is comparison with laparoscopic “unroofing” of the cyst as the first-line treatment. Laparoscopic unroofing of the cyst is now considered the standard surgical option, replacing other surgical techniques, including open cystectomy, hepatic wedge resection, and lobectomy. Laparoscopic unroofing is associated with reduced morbidity and mortality and better cosmetic results compared with other surgical techniques, with low rates of recurrence. However, laparoscopic unroofing may not be possible in patients with a superior or posterior location of the cyst.

A systemic review comparing PES with laparoscopic unroofing showed both procedures are effective at achieving partial or complete obliteration of the cyst and the relief of symptoms produced by the cyst. It also showed similar failure rates between the two treatment groups with a slightly lower risk of adverse events with PES. The study recommended PES as first-line treatment with laparoscopic unroofing indicated for patients with biliary or peritoneal communication, inability to exclude malignancy, or recurrence of cyst or symptoms after PES. However, due to differing endpoints in studies and the lack of randomization, it remains unclear which treatment is safest and most effective. At this point, the choice of treatment depends on local expertise and available equipment in an institution.

The other controversy is PES treatment performed for abdominal discomfort or pain. Care must be taken to exclude other etiologies for the patient’s symptoms before intervention. A trial of cyst aspiration without sclerotherapy can be performed to establish the diagnosis. If symptoms do not abate, the cyst in question is excluded as the cause of pain. Should pain resolve after aspiration and recur with cyst recurrence, PES may be advised.

Outcomes

PES is effective at reducing cyst volume and relieving the symptoms for which the procedure is performed. A systemic review of the literature performed by Wijnands et al. of 12 studies (414 patients) demonstrated a median proportional cyst volume reduction between 76% and 100% after a follow-up of 1–54 months. In the same review of 10 studies (321 patients), symptomatic reduction was achieved in 72%–100% of patients after a median follow-up period of 2–54 months. Complete symptom disappearance was reported in six studies (148 patients) and ranged from 56% to 100%. In a different study of 43 patients with symptomatic liver cysts, 39 patients (91%) showed resolution of symptoms as well as significant reduction in cyst volume. Eight hepatic cysts (19%) disappeared completely. The mean diameter of the cysts decreased from 12.5±4.4cm to 3.8±3.4cm during follow-up.

There is a slight difference in clinical outcomes in PES performed for solitary cysts versus for cysts associated with polycystic liver disease. Two studies showed symptom reduction and symptom resolution of 94% and 82%, respectively, for patients with solitary cysts. In contrast, only 72% of patients with polycystic liver disease reported symptom reduction, and 59% had complete resolution of symptoms.

Complications

Reported complications after PES are generally minor and transient and include pain, nausea, vomiting, postprocedure intracystic hemorrhage, and cyst infection. Ethanol intoxication, manifested by headache, flushing, and confusion, has been reported and is associated with longer duration of sclerotherapy (120–180 minutes) and larger volumes of ethanol. One of the more serious reported complications is irreversible sclerosing cholangitis, which may be seen in the setting of ethanol injection into a cyst that communicates with the biliary tree.

Postprocedural and Follow-up Care

If tolerated without immediate complication, PES can be performed as an outpatient procedure. Short-term follow-up at 1–2 months with US is generally performed, with further follow-up performed only for symptom recurrence. During early follow-up, the treated cysts may show an increase in size, which is likely due to transient reactive inflammatory reaction and not true recurrence. These “recurrent” cysts usually disappear within several months with mean regression time of approximately 6 months. Should symptoms recur in the setting of cyst recurrence, a second PES or laparoscopic deroofing may be considered.

Indications

PAIR is the first-line treatment for WHO stages CE1 and CE3a cysts (Gharbi types 1 and 2), especially those ≥5 cm. It is also indicated for patients who are not surgical candidates, patients who refuse surgery, pregnant women, and patients who failed surgery or medical management.