**6. Novel techniques in liver biopsy; modern non-invasive alternatives**

#### **6.1. Probe-based confocal laser endomicroscopy**

The latest development in histological evaluation of gastrointestinal structures is confocal la‐ ser endomicroscopy. It allows for the in vivo evaluation of dysplasia and malignancies of the gastrointestinal tract, or in order to obtain directed biopsies that would allow rapid and more precise diagnoses [52, 53]. The first embodiments of this technique required dedicated endoscopes to be used for evaluating cavitary structures accessible from both ends of the di‐ gestive tracts.

(length) x 0.4 cm (diameter), up to 5.5 cm below skin level. Its results are expressed as veloci‐

Risks and Benefits of Liver Biopsy in Focal Liver Disease

http://dx.doi.org/10.5772/52620

97

Fibrotest-Actitest (Biopredictive, France) is a serologic marker-based algorithm which repre‐ sents an alternative to invasive biopsy techniques. It received clinical validation in patients with chronic hepatitis B and C, ALD and NAFLD. Fibrotest consists of a panel of markers designed for appreciating liver fibrosis: Gamma-glutamyltranspeptidase (GGT), Total biliru‐ bin Alpha-2-macroglobulin, Haptoglobin, and Apolipoprotein A1. Necroinflammatory ac‐ tivity is appreciated through the Actitest component, which adds Alanine transaminase (ALT) to the above mentioned serum markers [3, 57]. All these tests are performed in vali‐ dated laboratories due to their complexity and variability of their different components and their results are inserted in a complex mathematical formula through a web-based interface, the end-result being correlated with other quantitative score systems such as METAVIR,

The best results are provided by a combination of two or more non-invasive methods, one study in particular finding that Fibrotest and Fibroscan offers the best diagnosis perform‐ ance compared to liber biopsy as a gold standard, at least for advanced fibrosis (F values beyond 2) or cirrhosis (F3 or F4) [2]. This conclusion was reached by another, more recent study performed by Boursier and his collaborators [59]. They diminish the number of pa‐ tients who require liver biopsy, however, this procedure is not excluded in all cases. Some studies have shown a high variability between Fibroscan results, dependent of the bodymass index and population factors [60, 61]. A discordance between liver biopsy staging and the estimation provided by non-invasive methods has also been identified [34]. It was ap‐ proximated that 30–40% of all patients investigated by a combination of non-invasive imag‐ istic and marker-based methods still require liver biopsy, during either sequential or

Despite all its limitations and the advances in modern lesser invasive techniques, liver biop‐

The main concern when turning to tissue sampling through biopsy is the risk/benefit ra‐ tio, the decision ultimately belonging to the clinician involved. The risks may at times be higher than the implied diagnostic outcome, in which case other methods are preferred

Currently, it is recommended that all interpretations should be based on proper tissue blocks, with the correct technique applied. It is preferred that more than one pathologist with extensive experience in liver pathology should formulate the final histological diagno‐ sis. This is especially true for FLLs and liver malignancies, as benign features may at times

sy remains the gold standard for evaluating a wide array of liver diseases.

ties, in m/s [4].

Knodell or Ishak [58].

simultaneous protocols [60, 61].

**7. Conclusion**

for the diagnosis.

overlap, making the diagnosis uncertain.

Recent advancements however were able to miniaturize the technology so the imaging mi‐ croprobe can be connected to 30,000 fiber-optic threads that enable point-to-point real-time detection at 12 frames/sec. The imaging device by itself measures less than 1.5 millimeters in diameter, thus allowing its use through 19G or tru-cut biopsy needles, or insertion by lapa‐ roscopy or NOTES [53]. This technology will allow in vivo, real-time imaging of liver histol‐ ogy, technically enhancing the capabilities of liver biopsy [54]. A few studies on animal models exist in the literature, detailing pCLE use for liver histological imaging [14, 55, 56]. The technique can be used for assessing the state of hepatocytes and the morphology of the liver tissue, or can be limited to the study of the exterior liver capsule, yielding interesting preliminary results in the setting of cirrhosis. Mennone et al reported interesting results re‐ garding a fibrotic pattern and collagen deposits in animal models with cirrhosis induced by bile duct ligation [14]. The technology shows promise and may someday allow for safer his‐ tological assessment of patients with chronic liver disease irrespective of its advancement, either cirrhotic or having any extreme complications, such as HCC.

#### **6.2. Non-invasive imaging and serum tests for the assessment of fibrosis**

Transient elastography (TE, Fibroscan® developed by Echosens, Paris, France) and Acoustic radiation force impulse (ARFI) are two ultrasound-based methods for quantifying liver fib‐ rosis without the need for histological assessment. Another approach is through serum markers of fibrosis quantification, processed in complex mathematical formulas which give a quantitative result for liver stiffness, such as the Fibrotest, Biopredictive and the aspartate transaminase to platelets ratio index (ARPI) approaches.

TE is a novel and rapid non-invasive examination which involves minimal patient discom‐ fort over a relatively low time period (one examination may take up to 5-10 minutes de‐ pending on the skeletal and adipose conformations of the patient). The device consists of a hand-held vibrating unit with an ultrasound transducer probe mounted on its axis, which generates medium amplitude vibrations at a low frequency, thus inducing an elastic shear wave in the underlying tissue. The hand-held probe is connected to a modified tower US machine which registers the result and through the on-screen software interface presents the user with an elastogram as a function of depth in time. The patient lies on his/her side and the probe is placed against the skin on the median clavicle line, directed towards the ana‐ tomical location of the liver, at a 90 degrees angle with the skin surface. Its results are pre‐ sented as kilo Pascals (kPa), units of applied force. A series of 10 measurements are mediated to present a final value of the liver stiffness, which is equivalent to an F-stage fib‐ rosis measurement obtained through biopsy [2].

ARFI is another technology that uses short-duration, high-intensity acoustic pulses which in turn exert mechanical excitation upon the tissues, generating local displacement resulting in shear waves. Their velocity can be assessed in a selected cylindrical area of interest of 0.5 cm (length) x 0.4 cm (diameter), up to 5.5 cm below skin level. Its results are expressed as veloci‐ ties, in m/s [4].

Fibrotest-Actitest (Biopredictive, France) is a serologic marker-based algorithm which repre‐ sents an alternative to invasive biopsy techniques. It received clinical validation in patients with chronic hepatitis B and C, ALD and NAFLD. Fibrotest consists of a panel of markers designed for appreciating liver fibrosis: Gamma-glutamyltranspeptidase (GGT), Total biliru‐ bin Alpha-2-macroglobulin, Haptoglobin, and Apolipoprotein A1. Necroinflammatory ac‐ tivity is appreciated through the Actitest component, which adds Alanine transaminase (ALT) to the above mentioned serum markers [3, 57]. All these tests are performed in vali‐ dated laboratories due to their complexity and variability of their different components and their results are inserted in a complex mathematical formula through a web-based interface, the end-result being correlated with other quantitative score systems such as METAVIR, Knodell or Ishak [58].

The best results are provided by a combination of two or more non-invasive methods, one study in particular finding that Fibrotest and Fibroscan offers the best diagnosis perform‐ ance compared to liber biopsy as a gold standard, at least for advanced fibrosis (F values beyond 2) or cirrhosis (F3 or F4) [2]. This conclusion was reached by another, more recent study performed by Boursier and his collaborators [59]. They diminish the number of pa‐ tients who require liver biopsy, however, this procedure is not excluded in all cases. Some studies have shown a high variability between Fibroscan results, dependent of the bodymass index and population factors [60, 61]. A discordance between liver biopsy staging and the estimation provided by non-invasive methods has also been identified [34]. It was ap‐ proximated that 30–40% of all patients investigated by a combination of non-invasive imag‐ istic and marker-based methods still require liver biopsy, during either sequential or simultaneous protocols [60, 61].
