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Alcohol Injection Ablation (PEI) PDF Print E-mail
Short Introduction

Principle
By injecting pure alcohol (i.e., ethanol) into the tumor bed, blood flow to the cancer is blocked. The alcohol induces tumor destruction by drawing water out of the tumor cells (dehydrating them) and denaturing the structure of the cellular proteins, resulting in complete ablation of the tumor.
Technique
The 100% (absolute) alcohol is injected through the skin (percutaneously) and into the tumor using a very thin needle with the help of ultrasound or CT guidance. It may take up to five or six sessions of injections to completely destroy the cancer.
Indication
Alcohol injection may be appropriate for patients with any of the following:
  • a single HCC lesion smaller than 5 cm in diameter
  • up to three lesions smaller than 3 cm in diameter that are localized but unresectable due to the location in the liver, concomitant medical considerations (cirrhosis), or even limited bilateral tumors
  • a lesion surrounded by a shell consisting of scar tissue (fibrous encapsulation) and not near the surface of the liver
Tumor response

Tumor response rates to alcohol injection have been reported to be 90-100% in liver cancer smaller than 2 cm in diameter, 70% in liver cancer of 3 cm in diameter, and 50% in 5 cm in diameter

 

 

Detailed Explaination

 

Percutaneous ethanol (alcohol) injection (PEI) therapy was first performed in 1983 inJapan. Ultrasound guidance is used to place up to absolute alcohol into the lesion. Now this modality has been widely used and is accepted as an attractive alternative to surgery in patients with small hepatocellular carcinoma (HCC).

 

PRINCIPLE

The toxic effects of ethanol are at the cellular level. Ethanol diffuses into the cell and causes nonselective protein denaturation and cellular dehydration, leading to coagulation necrosis. Subsequent fibrosis and small vessel thrombosis also contribute to cellular death.

 

PROCEDURE

Ethanol (Alcohol) ablation is generally performed under sonography guidance by using a 20-gauge needle. This needle has two side holes at its tip, which allows better dispersion of the alcohol into the tumor tissue. The needle tip is placed close to the peripheral margin of the tumor. Absolute alcohol (100%) is slowly injected under real-time ultrasound control. If the alcohol ran off quickly into the blood stream rather than staining the tumor tissue, as observed by real-time ultrasound, then this indicates that the needle tip is not in the substance of the tumor. The needle is then repositioned. The goal of this procedure is to achieve a black stain in the tumor tissue, as evidenced on imagings. A maximum of 10 ml of 100% alcohol is injected per site, with maximum of 20 ml per session. At the end the procedure, 1% Lidocaine is injected along the needle track as the needle is slowly being withdrawn. The injection appears to lessen the amount of discomfort the patient experiences following the session. The session is terminated prematurely, that is by using less than 10 ml of alcohol, if the patient experiences significant discomfort or if the tumor tissue appears to be completely ablates. The numbers of session per patient, generally, are once or twice per week for four to six sessions, depending upon the tumor size and the amount of residual tumor identifies on CT or ultrasonography.

 

INDICATIONS

The ideal patient for alcohol injection has fewer than three Hepatocellular Carcinoma (HCC) tumors, each of which is:

  • well defined (distinct margins)
  • less than 3cm in diameter
  • surrounded by a shell consisting of scar tissue (fibrous encapsulation)
  • not near the surface of the liver

Generally PEI is used in small liver cancer not suitable for resection, either because they are multiple, because of their position in the liver, or because of severe hepatic dysfunction. Patients with tumor recurrence or residual tumor after successful chemoembolization are also good candidates for PEI.

It does not appear that PEI will be as effective in the patient with metastatic cancer to the liver, since most metastases are relatively hard and avascular in a normally soft liver. This allows spillage of the alcohol into the surrounding liver substance, hurting the liver next to the tumor while not killing the tumor because the alcohol doesn't stay in place long enough to have the desired effect. On the other hand, in the hard, cirrhotic liver with a highly vascular and soft HCC, PEI is worth consideration as a method of liver cancer treatment.

PEI is contraindicated in patients with gross ascites, severe coagulopathy, obstructive jaundice, extrahepatic disease, and main portal vein thrombosis.

ADVERSE REACTIONS

The most common adverse effects of PEI are pain, fever, a feeling of alcohol intoxication and elevated transaminase. Pain most often is localized to the injection site. Occasionally pain is experienced elsewhere in the abdomen or the shoulder, probably related to leakage around the hepatic capsule. Pain and fever have been shown to be dose-related. With dose under 10 ml per session, pain sufficiently severe to require analgesia has been reported to occur in 11% to 13% of sessions versus 29% with injection doses greater than 10 ml in a given session.

Similarly, fever over 38 degrees celsius occurred in 6% of sessions in which the administrated dose was less than 10 ml versus 29% of sessios tn which more than 10 ml of ethanol were injected. Although the mechanism of the phenomenon has not be elucidated fully, it is likely to be in part related to the volume of tumor necrosis. Transient pain has also been shown to be more intense following injection of lesions on the surface of the liver than following injection of deeper lesions

Segmental chemical portal vein thrombosis has been known to occur in a few patients. Spontaneous resolution has been reported within 1-6 months in most cases.

Procedure-related mortality is rare. It was shown that this modality does carry the risk of disseminating the tumor by facilitating the passage of malignant cells into the blood stream, but that was opposed by other authors, who consider that because ethanol diffuse along the needle tract, its cytotoxic effect and small vessel thrombosis minimize the risk seeding.

FOLLOW-UP

Follow-up typically includes a combination of imaging, tumor marker assay, and selective use of fine-needle aspiration and biology (FNAB).Following serial levels of AFP in the cases of HCC is useful only in cases in which the serum levels of this marker is elevated prior to the initiation of therapy. Random FNAB is subject to sampling error, such that it is only definitive if positive for malignancy. This fact, together with the reliability of CT in differentiating tumor necrosis from residual tumor, has led to FNAB being reserved for equivocal cases.

Figure 1-2 Below is a CT scan of a patient with two liver tumors (depicted by the arrows). The patient underwent an injection with DTI-0l5, which produced death of both tumors (depicted by the dark homogenous masses and two white arrows).

 

Figure 3 Chemoembolization, hepatic. Contrast-enhanced axial CT scan through the liver in the portal venous phase in an 88-year-old woman who presented with right upper quadrant discomfort. Scan shows a 13-cm mass occupying the right lobe of the liver; it displaces the portal vein medially. Results of laparoscopic biopsy confirmed the mass to be a well-differentiated hepatocellular carcinoma in a noncirrhotic liver.



Figure 4 Chemoembolization, hepatic. Arterial/early capillary phase of a celiac-axis angiogram (same patient as in Image 3) shows extensive neovascularity in the mass, with stretching of the vessels around the mass.


Figure 5 Chemoembolization, hepatic. Portal venous phase of a celiac-axis angiogram (same patient as in Images 3-4) shows patent splenic and portal veins; therefore, the patient is a suitable candidate for chemoembolization.


Figure 6 Chemoembolization, hepatic. Contrast-enhanced axial CT scan through the liver (same patient as in Images 3-5) obtained 10 days after chemoembolization shows intensely concentrated lipiodol within the hepatocellular carcinoma. Note the considerable central tumor necrosis.


Figure 7 Transverse CT scans obtained in a 71-year-old woman with HCC in the hepatic dome. (a) Early-phase scan obtained before PEI shows a 1.4-cm nodule (arrow) in the anterosuperior segment of the liver. (b) At CT fluoroscopy, two needles were inserted into the nodule with a right-sided approach, and 10 ml of absolute ethanol was injected. (c) Early-phase scan obtained 1 year after PEI shows no enhancement (arrowhead) in the tumor area.


Figure 8 Transverse CT scans obtained in a 71-year-old woman with HCC in the hepatic dome. (a) Early-phase scan obtained before PEI shows a 1.4-cm nodule (arrow) in the anterosuperior segment of the liver. (b) At CT fluoroscopy, two needles were inserted into the nodule with a right-sided approach, and 10 ml of absolute ethanol was injected. (c) Early-phase scan obtained 1 year after PEI shows no enhancement (arrowhead) in the tumor area.


Figure 9 Transverse CT scans obtained in a 71-year-old woman with HCC in the hepatic dome. (a) Early-phase scan obtained before PEI shows a 1.4-cm nodule (arrow) in the anterosuperior segment of the liver. (b) At CT fluoroscopy, two needles were inserted into the nodule with a right-sided approach, and 10 mL of absolute ethanol was injected. (c) Early-phase scan obtained 1 year after PEI shows no enhancement (arrowhead) in the tumor area.


Figure 10 Transverse CT scans obtained in a 65-year-old woman with a recurrent nodule after transcatheter arterial embolization. (a) Early-phase scan obtained before PEI shows a 2.3-cm recurrent nodule (arrows). (b) A PEI needle was introduced into the nodule with the coaxial method, and 10 mL of ethanol was injected with CT fluoroscopic guidance. ChestCT scan (not shown) obtained immediately after PEI showed no pneumothorax or pleural effusion.


Figure 11 Transverse CT scans obtained in a 65-year-old woman with a recurrent nodule after transcatheter arterial embolization. (a) Early-phase scan obtained before PEI shows a 2.3-cm recurrent nodule (arrows). (b) A PEI needle was introduced into the nodule with the coaxial method, and 10 mL of ethanol was injected with CT fluoroscopic guidance. ChestCT scan (not shown) obtained immediately after PEI showed no pneumothorax or pleural effusion.