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IMAGE GUIDED LIVER BIOPSY
L RAGHURAM, ASHA JUSTUS, SHALINI GOVIL
Department of Radiology, Christian Medical College and Hospital, Vellore 632 004, Tamil Nadu.
With the widespread availability of ultrasound scanners and the low probability that a blind biopsy will be successful in obtaining tissue from a focal liver lesion, image guidance has come to play a pivotal role in the diagnosis of focal liver disease. Blind hepatic biopsy of focal liver lesions have a reported sensitivity as low as 20%. Image guided liver biopsy is the accepted method of establishing the nature of these lesions.[1] In the diagnosis of suspected liver disease, transjugular liver biopsy is an accepted alternative to percutaneous liver biopsy in patients with coagulopathy or ascites.[2]
INDICATIONS
The setting in which a focal liver lesion is detected can vary from a small incidentally discovered solid lesion to a cystic lesion in a patient with a known primary tumour. Although a tissue diagnosis of all these lesions would be ideal, a judicious set of specific indications would avoid exposing patients to the unnecessary risks of percutaneously penetrating a vital, vascular organ. Equally, it is important to distil from this set, those lesions that can be accurately characterised by imaging alone and those situations where the benefit of accepting a non-tissue diagnosis (based on imaging, clinical setting and serum markers) outweighs the risk of biopsy.
Note - By "lesion" we refer to focal abnormalities in the liver that are greater than 1 cm in size. Those less than 1 cm are too small to accurately characterise on imaging and usually too small to percutaneously biopsy.
The following is a comprehensive list of indications for an image guided liver biopsy:
1.To characterise a focal liver lesion in a patient with no known primary malignancy
2.To confirm metastasis or diagnose a second primary tumour in a patient with a known malignancy
3.To obtain a sample for lab analysis and gain access for the percutaneous drainage of a liver abscess
4.To establish persistence of tumour after therapy
5.To establish rejection in liver transplant patients
6.To guide biopsy in diffuse liver disease when the liver is small or abdominal anatomy is altered
Focal liver lesions that can be characterised by imaging: These lesions do not need biopsy confirmation if they strictly adhere to certain diagnostic criteria.
1.Haemangioma - Time density CT: initial bright blotches of peripheral enhancement with gradual centripetal filling-in attaining a density similar to normal liver on delayed scans.
2.Simple cysts - US : smooth or lobulated, anechoic lesions with an imperceptible wall and definite posterior enhancement.
3.Focal fatty infiltration - Triple phase spiral CT: Hyperdense lesions in a periligamentous or subcapsular location that are isodense to the rest of the liver on the venous phase.
4.Focal fatty sparing - Triple phase spiral CT: Hypodense lesions in a periligamentous or subcapsular location that are isodense to the rest of the liver on the venous phase.
Situations where the benefit of accepting a non-tissue diagnosis (based on imaging, clinical setting and serum markers) outweighs the risk of biopsy:
HCC in a patient with chronic liver disease - CT/MRI : solid lesion that enhances on arterial phase or is bright on T2W in a patient with known CLD and raised AFP. These lesions can be assumed to be foci of HCC if the risk of percutaneous puncture is unacceptably high.
Note - Always search for other more safely accessible sites for biopsy. Particularly in suspected disseminated disease, tuberculosis, sarcoidosis, malignancy and lymphoma, open biopsy of a significant axillary, supraclavicular or cervical node is always both safer and more reliable than a guided liver biopsy in terms of accurate histology. Clinical colleagues should be advised to repeat a thorough search of the body for peripheral adenopathy. In the past we have directed the clinical examination to significant nodes found in the periphery on CT thorax or with high resolution US of the neck and axilla.
RELATIVE CONTRA-INDICATIONS
It is important to address certain controversial situations that, depending on local expertise, may be considered a contraindication to percutaneous biopsy.
Coagulopathy - If the lesion is one that cannot be accurately characterised by imaging and if no other more easily accessible site for biopsy is available (i.e. significant axillary, supraclavicular or upper deep cervical neck nodes), hepatic biopsies can be performed safely in patients with coagulopathy after correction with appropriate clotting elements.[2] Large bore needles are not recommended.
Suspected haemangiomas with atypical appearances on Time-density CT - There has been considerable controversy over the biopsy of hepatic haemangiomas. Several studies have shown that haemangiomas can be safely biopsied with an 18 G or 20 G needle with an acceptable complication rate.[3]
Ascites - is not a contraindication to percutaneous liver biopsy.[2,4] Few studies, which have addressed the safety of performing a liver biopsy in patients with cirrhosis in the presence of ascites, have reported low complication rates.[3]
Biliary Obstruction - In patients with obstructive jaundice large bore needles (19 gauge or larger) should be avoided.[1]
PRE PROCEDURE EVALUATION
This includes review of prior diagnostic imaging studies, bleeding history, bleeding parameters, and written informed consent.
Coagulopathy assessment
Prothrombin time (PT), partial thromboplastin time (PTT) and platelet count should be obtained prior to biopsy. When the platelet count is less than 100,000/ml, PT is prolonged by > 3 seconds relative to the control and PTT is prolonged by > 6 relative to control the biopsy, if absolutely necessary, is done after administration of the appropriate clotting elements. When the coagulopathy is severe in patients with diffuse liver disease, transjugular biopsy is performed.
Although a mild sedative is given prior to the procedure, antibiotics are not routinely administered except during hepatic abscess drainage when catheter manipulation can cause septicaemia.
Choice of Modality for Image Guidance : Ultrasound is the guidance modality of choice whenever the lesion can be seen by ultrasound imaging. Real time guidance during needle placement is helpful in avoiding major portal and hepatic veins. CT is preferred during drainage tube insertion in the superior segments to avoid transgression of the pleural space. The use of real-time CT guided biopsy is in its infancy and more experience will be required before indications for this potentially useful method can emerge.
Needle Selection : This depends on the type of lesion and the presence of coagulopathy. In patients with diffuse liver disease, hepatic lymphoma, most focal liver lesions or a hepatic transplant, a large core biopsy is required. For this, an 18-gauge Tru-Cut needle loaded onto a biopsy gun is recommended although, theoretically, needles upto 14 gauge can be used.[3] In a blinded evaluation of 20 automated cutting biopsy devices, most 18-gauge needles with at least a 2 cm excursion provided a high quality, diagnostically adequate specimen for histopathologic analysis.[5]
For lesions that require a needle course through major vessels or bowel, for vascular lesions and in the presence of coagulopathy a non-cutting needle small bore needle such as a Chiba 20-gauge needle should be used.
Technique : The two main techniques for ultrasound-guided biopsies are the free hand technique and attached needle guide technique.
The approach is usually lateral or anterolateral, intercostal or sub costal for the right lobe and anterior for the left lobe. This is obviously further determined by the site of the lesion, hepatic lobar and vascular anatomy. The biopsy should be performed during suspended respiration to avoid lacerations. It is important to interpose a cuff of normal parenchyma between the liver capsule and the margin of a lesion.
Complications : Complications from image-guided biopsies are uncommon with a reported 0.83 % complication rate for fine needles and 1.44% for larger cutting needles. Minor complications include transient localized discomfort at the biopsy site, post procedure pain sufficient to require analgesia, and mild transient hypotension. In some series, these occur in as few as 2% to 5%, but they can be as high as 50% in others. Major complications include hypotension with a systolic blood pressure < 90 mm Hg, bleeding into the peritoneal cavity or thoracic cavity, haemobilia, a clinically apparent intrahepatic haematoma, pneumothorax, gallbladder perforation, enteric perforation or an inadvertent biopsy of another organ such as the kidney or pancreas, myocardial infarction, development of a clinically significant cardiac arrhythmia, respiratory arrest, and death.
Liver biopsies performed on patients with neoplastic disease are known to have the highest overall rate of major complications.
Liver biopsies can be performed in liver transplant recipients with an overall low rate of major complications (0.2%).[6]
Post Procedure Care : Since symptoms related to significant post biopsy haemorrhage is noted within 3 hours after the procedure the patient has to be monitored during this time.[1]
Accuracy : The reported accuracy of image-guided percutaneous hepatic biopsy varies from 61% to 100%. The lower accuracy rates have been obtained with fine-needle aspiration of benign hepatic lesions, accurate diagnosis of which is facilitated by large core biopsies.[1] Diagnostic accuracy of "skinny" needle biopsy for hepatic malignancy is greater than 93%.[7]
TRANSJUGULAR LIVER BIOPSY
Transjugular liver biopsy is an elegant method of performing liver biopsy in patients with massive ascites and / or prolonged prothrombin time, both common occurrences in liver disease. The technique can also be extended to diagnose and angiographically treat Budd Chiari syndrome when this abnormality is encountered during a transjugular liver biopsy.
Indications : include
1) Presence of massive ascites
2) Presence of massive obesity
3)Severe coagulopathy
4) Failed percutaneous biopsy
5) Suspected vascular tumour or peliosis hepatis
6) Need for ancillary vascular procedures (TIPS, venography)
Contraindications : There are no major contraindications. Thrombosis of the internal jugular vein is a relative contraindication. Uncooperative and paediatric patients may require anaesthesia. The angulation of the right hepatic vein with the IVC might be acute and hinder access with the metallic cannula.
METHOD
Prior to the procedure the patient should be fasted for four hours. The procedure is performed under mild sedation. ECG monitors the heart rate and rhythm throughout the procedure, this being important as the right atrium is traversed.
The patient is placed in the supine position with the foot end of the table elevated to distend the jugular vein and also prevent air embolism. The jugular vein is imaged with high frequency ultrasound, which also helps to define the relation of the carotid artery to the jugular vein. A 9 French sheath is introduced into the right jugular vein using the Seldinger technique. A multipurpose catheter is used to cannulate the right hepatic vein. A deep inspiration decreasing the angulation of the right hepatic vein with the IVC, improves cannulation. Hepatic venography is optional and can be done if there is a suspicion of Budd Chiari syndrome.
Over a guide wire introduced into the hepatic vein a metallic introducer is inserted. The metallic cannula has an outer polyurethane sheath. The biopsy needle is introduced through this metallic cannula. The needle should be pointed anteriorly while cutting the tissue. Also it is important to do biopsy during suspended respiration. Since the needle exits the hepatic vein into the liver parenchyma and then cuts the tissue, any bleeding is usually into the venous system (Fig. 2). Care should be taken not to introduce the needle too far into the hepatic vein to avoid traversing the capsule. The metallic needle is left in place to repeat the biopsy and take more tissue for culture / dry weight copper etc.
The transjugular biopsy set that we regularly use is the LABS 100 set marketed by Cook Inc (Bloomington, USA).
Post Procedure Care : After removal of the needle and sheath the patient should be nursed in the sitting position for 4 hours. This keeps the jugular vein collapsed and prevents puncture site haematoma formation. The abdominal girth and vital parameters are monitored to check for haemorrhage.
Complications : are rare but include perforation of the liver capsule (3.5%), intraperitoneal haemorrhage (0.5%), transient cardiac arrhythmias during catheter passage through the right atrium, transient hoarseness or Horner's syndrome caused by local anaesthetic, haematoma at the puncture site, and puncture of the internal carotid artery.
Success Rate : Adequate tissue is obtained in 64 to 100% of cases.[7] Success rate with aspiration biopsy is 68% and with trucut biopsy is 97%.[8]
Our Experience : Over the past 5years we have performed 337 transjugular biopsies with a diagnostic success of 97%. We encountered complications in 10 patients, 7 of whom had capsular tears and 3 had haemobilia. Of these 10 patients, 7 patients needed angiographic embolisation while the other 3 were managed conservatively with correction of a deranged coagulation profile.
REFERENCES
1. Fernandez MP, Murphy FB. Hepatic biopsies and fluid drainages. Radiol Clin North Am 1991; 29 : 1311-28.
2. Gamble P, Colapinto RF, Stronell RD, Colman JC. Transjugular liver biopsy: A review of 461 biopsies. Radiology 1985; 157 : 589-93.
3. Paulson EK, Nelson RC. Techniques of percutaneous tissue acquisition. In Richard M Gore, Marc S Levine (eds) Textbook of Gastrointestinal Radiology (2nd ed). Philadelphia : WB Saunders, 2000; 1219-33.
4. Douglas BR, Charboneau JW, Reading CC. Ultrasound-guided intervention. Radiol Clin North Am 2001; 39 : 415-28.
5.Hooper KD, Abendroth CS, Sturtz KW, et al. Automated biopsy devices- a blinded evaluation. Radiology 1993; 187 : 653-60.
6. VanThiel DH, Gavaler JS, Wright H, Tzakis A. Liver biopsy - its safety and complications as seen at a liver transplant center. Transplantation 1993; 55 : 1087-90.
7. Chrisman HB, Saker MB. Angiography and Interventional Radiology of the liver. In Richard M Gore, Marc S Levine (eds) Textbook of Gastrointestinal Radiology (2nd ed). Philadelphia : WB Saunders, 2000; 1463-76.
8.Sada PN, Ramakrishna B, Thomas CP, Govil S, et al. Transjugular liver biopsy: a comparison of aspiration and trucut techniques. Liver 1997; 17 : 257-259.
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