Diagnostic and Interventional Imaging (2014) 95, 665—675

CONTINUING EDUCATION PROGRAM: FOCUS. . .

Percutaneous hepatic ablation: What needsto be known in 2014

O. Seror

Department of Radiology, Jean-Verdier Hospital, avenue du 14-Juillet, 93140 Bondy, France

KEYWORDSLiver;Malignant tumor;Monopolarradiofrequencyablation;Multipolarradiofrequency

Abstract Percutaneous treatments for liver tumors were initially reserved for patientsdeemed to be inoperable and whose tumors were small in both size and number. As a resultof the widening range of both techniques and technologies these treatments have graduallybecome incorporated into increasingly complex treatment strategies for increasingly broadpatient groups. The place reserved for these techniques, which are still dominated by monopo-lar radiofrequency ablation, which is now facing strong competition from second-generationmicrowaves, is governed by each center’s knowledge and skills in the techniques. This reviewdescribes the possible indications for percutaneous ablation depending on clinical findings and

ablation;Electroporation

the technical and technological choices made.© 2014 Éditions francaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

In the last two decades, percutaneous treatments for malignant liver tumors have advancedconsiderably. They are better tolerated than partial hepatectomy [1—3] and can radicallytreat tumors, which are small in both size and number with very few contraindications[4,5]. The most widely used method of those available has been monopolar radiofrequencyablation, although in the last 2 years this has attracted strong competition from microwaves[6], which have seen major technological advances. Other techniques such as multipolarradiofrequency ablation [7] and irreversible electroporation [8] use implantation of severalelectrodes operating in pairs in bipolar mode. These methods, which are conceptually

very different from monopolar radiofrequency ablation and microwaves, are bringing newprospects for treatment.

Generally, compared to older chemical methods such as alcoholization, physical abla-tion techniques produce more predictable results, which are almost independent of the

E-mail address: olivier.seror@jvr.aphp.fr

http://dx.doi.org/10.1016/j.diii.2014.04.0022211-5684/© 2014 Éditions francaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

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Figure 1. a: diagrammatic representation of an ablation areawith ideal centrifugal extension from a central tumor energysource: monopolar, mono-electrode radiofrequency (RF) ablation,mono-aerial microwave ablation, monofiber laser ablation, mono-applicator cryoablation; b: diagrammatic representation of ablationby ideal summation (sequential or simultaneous) of three ablationareas with isometric centrifugal extension from three paracentralenergy sources within the tumor. Multi-electrode, monopolar RFam

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aitrodes, which are activated sequentially in pairs (Fig. 2).It is no longer necessary with this device therefore to usea dispersion electrode as all the energy produced by thegenerator is delivered into the treatment area. Unlike the

Figure 2. Diagrammatic representation of multipolar ablation bysequential bipolar activation of all electrode pairs (three electrodesallowing three possible combination of electrodes pairs). The abla-tion area extends centripetally between the three energy sources

66

ype of tumor. Several randomized trials [9—11] have con-rmed that radiofrequency ablation is superior for thereatment of hepatocellular carcinoma (HCC). There haseen an underlying trend in the last few years to userst line percutaneous physical ablation techniques to treatmall malignant liver tumors in favor of excision surgery3,5,12—14].

uiding and monitoring percutaneousepatic ablation

ltrasound computed tomography (CT) and to a lesserxtent, magnetic resonance imaging (MR) can be usedor percutaneous hepatic ablation. The choice of methodepends less on the operator’s usual practice than on thentrinsic properties of each of the methods. There are noomparative studies available as yet on this subject andt is quite remarkable that almost all of the major seriesublished have been carried out under ultrasound guidingnd monitoring [4,5,12]. This preference in the expert cen-ers is undoubtedly partially explained by its low cost andeady availability of ultrasound. Furthermore, however, thentrinsic properties of ultrasound: multiplanar examination,eal time and excellent unenhanced tissue contrast reso-ution makes ultrasound perform extremely well in guidingnd monitoring percutaneous ablation of liver tumors [15].he predominant role of ultrasound in this situation shoulde further increased by the use of microbubble contrastedia and the major advances in 3D imaging, fusion and

nstrumentalized geolocalization [16].The new flat sensor angiography tables allow 3D CT-like

mages to be obtained and should shortly also become nec-ssary guiding and early assessment tools for percutaneousblation techniques. In addition, and unlike CT, they offeraximum patient accessibility making ultrasound extremely

asy to use simultaneously in guiding and monitoring proce-ures.

adiofrequency ablation technologies andheir results

he generic term ‘‘radiofrequency’’ in reality poorly reflectshe large technological differences between instruments.onopolar mode, which is still at present by far the mostidely used (a generator connected to two electrodes: onective electrode is implanted in the center of the treatmentrea and the second ‘‘passive’’ electrode is a dispersionlate stuck onto the patient’s skin) in fact groups togethereveral devices which are very different in design (Fig. 1). Inrder to increase the volume of tissue destroyed by impactith these systems, energy diffusion from the active elec-

rode implanted in the tumor must be improved. Threeajor concepts have been developed to achieve this; theseiffer mostly in the design of the electrodes, which mayither be linear or deployable.

A few animal model studies have shown that the shape

nd volume of the ablation areas obtained in the liver canary depending on the monopolar device used [17,18]. Dif-erences can also be seen on an intention-to-treat basis ashe feasibility of treatment varies for a given site depending

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blation, multi-aerial microwave ablation, multifiber laser ablation,ulti-applicator cryoablation.

n the design of the electrode. Deployable electrodes areore difficult to use for superficial tumors. Linear elec-

rodes, which are not bulky and can be seen in a single planeection, are undoubtedly more straightforward to position,articularly for sites considered to be difficult.

Another system operating in multipolar mode has beenvailable in clinical practice for several years. This involvesmplanting several (up to six) cooled bipolar linear elec-

mplanted in the periphery of the tumor or even, if the tumor is suf-ciently small, outside of the tumor = ‘‘no touch’’ technique. Thisype of procedure is only possible with multi-electrode multipolaradiofrequency and irreversible electroporation.

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monopolar systems, the tissue is not destroyed by centrifu-gal diffusion of heat from the electrode but centripetallyin the spaces between each electrode pair. As a result, inmultipolar mode it is no longer the center of the tumorbut its periphery, which needs to be punctured. Comparedto conventional monopolar devices, this system has severalfundamental advantages: improved energy efficiency forthe same sample power and in particular more predictablemargins of the ablation areas produced (determined byimplanting the electrodes). These advantages have beendemonstrated in several pilot studies, which, in particu-lar, have shown that it has become possible to completelydestroy tumors with a diameter well in excess of threecentimeters [19,20]. In addition, in multipolar mode, it isno longer necessary to puncture the tumors themselves,which can be treated using the concept of ‘‘no touch abla-tion’’, borrowed from oncology surgery [19]. As a result, farmore than being a technological advance, multipolar modehas introduced a genuine paradigm shift into percutaneoustumor ablation.

Microwave technologies and their results

Like radiofrequency, microwave is a hyperthermia ablationtechnique and Penn’s biothermodynamic equation [21] alsoapplies when modeling the final result of tissue destruc-tion by microwave ablation. In addition, like monopolarradiofrequency ablation, energy is propagated centrifugallyfrom the electrode (aerial). Here again, several electrodescan be used simultaneously, as in monopolar radiofrequencyablation, to increase the ablation volume primarily by sum-mating the areas of destruction around each electrode. Ifthe intention is to create a continuous area of ablation,as in monopolar radiofrequency ablation the aerials needto be positioned in such a way that the individual ablationareas overlap (Fig. 1). If the intention is to obtain the sameresult with a single aerial, as in single electrode monopolarradiofrequency ablation, several successive ablation cyclesneed to be performed, moving the aerial after each impactin order to overlap the areas destroyed.

By design, therefore, microwave is subject to the samelimitations as conventional monopolar radiofrequency abla-tion, although the second-generation microwave devices,which have recently become available, have reignited inter-est in the technology, as the transfer of microwave energyto tissue is more efficient than with radiofrequency. Amicrowave electromagnetic wave excites water moleculesover a radius of approximately 2 cm (from the center ofthe aerial) whereas a radiofrequency wave mobilizes ioniccharges located within a radius of just a few millimetersaround the electrode. With microwave, therefore, the pas-sive tissue heat conduction effect contributes less to thefinal volume of the area destroyed than with radiofrequencyablation. The microwave temperature peaks are higher andachieved faster than with radiofrequency. In addition, andunlike radiofrequency ablation, carbonization of tissue incontact with the microwave aerial (which generally occurs

as the temperatures reached are > 100 ◦C) does not stop theprocess of energy transfer to the tissue.

How does this work in clinical practice? It is clear thatfor the equivalent volume of tissue destruction microwave

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s considerably faster than radiofrequency ablation [22],lthough at present there are no convincing clinical resultso confirm that it is possible with microwave to extendhe limits of maximum tumor size, which can be destroyedhrough impact without increasing the risk of complications.n practice, and as with monopolar radiofrequency ablationeyond 1.5 cm either side of the electrode with, the finalesults are variable a single energy delivery cycle (withoutepositioning), as they are very dependent on the tissueacro- and microperfusion conditions. In addition, and

nlike radiofrequency ablation in which tissue impedanceoutinely rises during the procedure, with microwave theres currently no tissue feedback, which can be used to judgehe progress of the ablation. The charts provided by theanufacturers are of limited use as they are produced from

x vivo experiments. The increase in ablation volumes byicrowave reported in some clinical studies is more due to

requent repositioning of the aerials during the proceduresfacilitated by the short energy delivery cycles of 1/3 to/2 of those with RF) than to the greater intrinsic efficiencyf microwave [23]. At present, there is therefore no seri-us argument to routinely recommend the use of microwaveblation to treat tumors over 3 cm in size. As with monopolaradiofrequency ablation, the need to reposition electrodesor tumors over 3 cm in size makes microwave ablation lessredictable and higher risk.

rreversible electroporation technologynd its results

rreversible electroporation causes delayed or immediateell death by permanently damaging the membrane func-ion of cells which are exposed to a very high potential1000 V—3000 V) high intensity (20 A—50 A) pulsed electri-al field lasting a few microseconds (50 �s—90 �s) [8]. Theselectromagnetic field pulses trigger massive local mobiliza-ion of tissue ionic charges, which exceed the physiologicalapacity of cell membrane transport, irreversibly inter-upting the cells homeostasis. Unlike the other physicalestruction techniques, electroporation is not therefore ahermotherapy although there is a minor Joule effect.

The results of electroporation are not therefore inrinciple affected by the thermal blood flow convectionffect. In addition, as the Joule effect of electroporations negligible, the method does not denature macropro-eins such as collagen fibers. Although their cell components ‘‘affected’’ the ‘‘electrophoresed’’ tissues retain anntact connective tissue architecture. Small bile ductulesnd vessels within the electroporesed areas therefore oftenemain patent. Electroporation is therefore particularlyromising to treat central hilar liver tumors in which ther-otherapies are contraindicated because of the risks ofiliary stenosis. In practical terms, alongside multipolaradiofrequency, ablation electroporation also relies on therinciple of implanting several electrodes (2 to 6), whichre sequentially activated in pairs in bipolar mode (Fig. 2).

lectrolocalization is a technique, which is still not widelysed: few clinical results have been published and patientumbers have been small, with limited follow up. Neverthe-ess, its specific aspects, which make the method a relatively

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afe treatment option in inoperable juxtahilar liver tumorsave been confirmed [24].

ther technologies

ther physical destruction methods are used includingaser photocoagulation, cryotherapy and focused ultra-ound. Although clear technological improvements haveeen made with these techniques over recent years, theirse in treating liver tumors is still marginal. They have notet shown to offer sufficient advantages over other thermalethods to justify their more widespread use.

ndications and contraindications forercutaneous ablation of liver tumors

ndications

urative treatmentlongside excision surgery, percutaneous ablation tech-iques form part of the radical curative local treatments.hey are therefore conventionally considered in patients

ho do not have widespread disease and who do not havextrahepatic spread. The most widely accepted rule for per-utaneous treatment to be used is the rule of ‘‘two 3s’’: 3 cmaximum diameter and up to 3 concomitant sites.

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igure 3. Eighty-one-year-old female patient with a peripheral cholanultipolar radiofrequency ablation. The mass on computed tomography

nd sagittal (c) sections. One month after multipolar radiofrequency abrtificial ascites: axial (d) coronal (e) and sagittal (f) CT showing compleuprahepatic vessels.

O. Seror

The debate over the place of percutaneous treatmentsompared to their direct competitor, excision surgery, istill wide open. Radiofrequency ablation is still very oftenescribed as a salvage treatment in patients not acceptedor excision, although there are no robust data justifying thistrategy either for metastases (of colorectal cancers) [25]r for HCC [26]. For similar patient groups, survival afterurgery is not significantly better than after radiofrequencyblation [14,27], although compared to excision, radiofre-uency treatment is far better tolerated and less expensive.t can also be easily repeated in the event of recurrencewhich occurs in over fifty per cent of patients 5 years afterxcision or percutaneous treatment, both for metastasesnd for HCC). As a result, there is now a strong basis forffering patients radiofrequency ablation first line for smallumors (≤ 3 cm in monopolar mode and ≤ 5 cm in multipolarode), including those with operable disease.

ombined treatmentsercutaneous treatments are usually only considered inore extensive disease in combination with other treat-ents such as hepatectomy, chemotherapy for metastases

6] or chemoembolization for HCC. The purpose of theseombined treatments is also to completely eradicate any

ctive lesion (0 residual tumor [R0]). Multipolar mode, whichan completely and reproducibly destroy tumors up to 8 cmn diameter [19] can reduce the need for treatment combi-ations, which can occasionally be poorly tolerated (Fig. 3).

giocarcinoma 8 cm in diameter in the dome of the liver treated by (CT) before treatment in the portal phase on axial (a) coronal (b)lation (6 electrodes) and protection of the diaphragm by creatingte destruction of the tumor area up to contact with the portal and

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The arrival of second-generation microwave devices enable‘‘one shot’’ ablations of small tumors (≤ 3 cm) in under threeminutes (application) and offers future prospects for multi-focal disease (> 3 sites) or multiple recurrences (multicentercarcinogenesis). In this case, ablation appears to be used lessto eradicate the cancer than to attempt to achieve long-term control, preserving patient’s best possible quality oflife.

‘Holding’ treatment pending liver transplantationfor HCCPatients in France with a small HCC (Milan criteria: 1 nod-ule ≤ 5 cm or up to 3 nodules ≤ 3 cm), which has developedin well-compensated cirrhosis (Child-Pugh A) have waitingtime of approximately 1 year for a transplant. The ques-tion therefore often arises as to the benefit of treating theHCC pending transplantation in order to keep the patientwithin the Milan transplantation criteria. Percutaneoustreatments, chemoembolization and even a combination ofboth techniques are often used in this situation. Some Euro-pean centers have reported that over 30% of patients whohave not been treated come off the waiting list because oftumor progression [28]. In reality, the problem which arisesis not to know whether percutaneous treatments can keeppatients within the eligibility criteria for transplantation(the answer to this is obviously yes) but to ensure that thepost-transplant prognosis of patients who have had ‘hold-ing’ treatment pending transplantation is similar to that inpatients who have been transplanted as early as possible.There is, however, no tangible evidence in the literature toanswer this question, although it is a crucial one. The riskof tissue dissemination along the needle puncture path isoften cited as a reason to opt for chemoembolization pend-ing transplantation. This solution does not appear to be wellfounded as chemoembolization only achieves total necro-sis of small HCC in under a third of cases [29]. Becauseof the shortage of transplants, access to transplantationis being increasingly limited for patients with HCC who do

not have liver impairment. In reality, the majority of these‘‘technically transplantable’’ patients will never be trans-planted. ‘‘Holding’’ treatment is therefore more likely tobe the only first line tumor therapy, which they will receive

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Figure 4. Sixty-year-old male patient with superficial hepatocellular

quency ablation. Computed tomography (CT) in the arterial phase (a) sin diameter. One month after no touch multipolar radiofrequency ablaexcellent safety margins.

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or several months. This treatment should therefore be asadical as possible in order to offer the patient the besthances of long-term survival. Using the Milan criteria andpart from excision, only percutaneous destruction tech-iques are potentially curative and they should therefore besed in priority, including situations when transplantations planned, because, as described above, transplantations far from a certainty in patients with good liver func-ion. In addition, a ‘‘salvage’’ transplant is still possiblen these patients if their HCC recurs after percutaneousreatment [19]. The risk of dissemination should not there-ore be overstated and should always be assessed dependingn the specific clinical situation. Risks of dissemination arencreased in:

subcapsular tumors which cannot be approached with-out passing through non-malignant liver tissue (less than1 cm);when initial (unprotected) biopsies have been taken;greatly elevated serum �-fetoprotein concentrations;poorly differentiated tumors (> Edmonson grade II).

In these situations, ‘‘no touch’’ multipolar mode is a veryttractive alternative [19] (Figs. 2 and 4).

alliative treatmentartial resection of malignant liver tumors does not signifi-antly prolong patient survival and surgical tumor reductions therefore not indicated. In addition, hepatectomy cannly be considered in patients with liver metastases if therocedure would remove all visible tumors (R0). This sur-ical concept has been extrapolated to the percutaneousreatments which are not conventionally therefore indi-ated for palliative use. One randomized trial, however, hashown that the combination of radiofrequency ablation withhemotherapy significantly prolongs survival in patients withetastatic liver disease (colorectal in origin) in whom R0

xcision cannot be achieved [30]. No comparable data areurrently available for HCC. It is possible, however, that as

n the example of the palliative treatment par excellence,hemoembolization, a reduction in tumor volume with per-utaneous treatment could lead to improved survival inome patients.

carcinoma in segment III treated by no touch multipolar radiofre-hows a subcapsular, hepatocellular carcinoma in segment III, 3 cmtion the CT (b) shows appearances of complete destruction with

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ontraindications

emostasishere are few absolute contraindications and these areostly concern patients at high risk of bleeding. Conven-

ionally, patients with serious coagulation abnormalities areherefore excluded. The contraindications to percutaneousreatments for most groups are:

prothrombin ratio < 50%;platelet count < 50,000;activated partial thromboplastin time > 10 points over thecontrol.

Although not formally proven, thermoregulation of theeedle puncture path at the end of the procedure by slowlyithdrawing activated electrodes ‘‘hot withdrawal’’ (which

s impossible with electroporation and difficult or even dan-erous with microwave) is recommended in order to reducehe risk of bleeding. This maneuver also reduces the risk ofumor dissemination.

irrhosisaradoxically, cirrhosis does not appear to either increaser worsen bleeds after percutaneous ablation. The risks ofiver decompensation, however, are greater in patients whoave the most severe coagulation abnormalities.

Clinical ascites is also one of the contraindications foradiofrequency ablation, as the risk of bleeding appears toe greater. Major ascites on a background of cirrhosis is anndication of serious liver dysfunction, a situation, whichenerally contraindicates any treatment for HCC.

iteome anterior subcapsular tumors cannot be puncturedirectly without passing through non-malignant liver tissue.he risk of bleeding complications and tumor dissemination

s greater in this situation. Limited resection is often the best

lternative treatment for these tumors and is a particularlyeasonable option as the procedure is technically straight-orward and limited. As we have described, if surgerys contraindicated, ‘‘no touch’’ multipolar radiofrequency

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igure 5. Sixty-five-year-old female patient with left intraportal heparaphy in the arterial phase (a) shows a left intraportal hypervascular maynamic MRI in the arterial phase (b) shows appearances of complete de

O. Seror

blation is an attractive alternative to percutaneous meth-ds (Fig. 4).

Other tumor site contraindications are often quotedepending on the center, equipment, technique and experi-nce of the operators. Some tumor sites carry large risksf collateral damage. This applies particularly to centralhilar) tumors, which carry a risk of biliary stenosis. Treat-ent of tumors located close to the gastrointestinal tract,articularly the colon, are at greater risk of peritonitis fromerforation and the minimum safe distance of 1 centimeteretween the border of the tumors and these structures isommonly recommended. Some preventative measures suchs cooling the biliary tract by endoluminal injection of icedater when the energy is delivered or retracting the treat-ent area from gastrointestinal structures by hydro- or gasissection, allow these sites to be treated in some situationshen no surgical alternative is available [3].

Percutaneous treatment of other sites such as tumorsocated close to the gallbladder or diaphragm also requiresome precautions, particularly when the contact areasxtend over a centimeter. In order to protect the diaphragmrtificial ascites is created with dextrose before the proce-ure (filling the peritoneal cavity by injecting 1 to 3 L of 5%lucose with the patient in the Trendelenburg position). Theallbladder can be drained preventatively or even cooled byirculating water (in this case the cooling circuit requiresual catheterization of the gallbladder). In addition, elec-roporation, which is not a thermotherapy, could be a firstine technique in these situations, if its preliminary resultsre confirmed (Fig. 5).

on-functional sphincter of Oddiatients with a previous history of biliary-gastrointestinalnastamosis or sphincteroctomy have a 50% risk of develop-ng an abscess in the thermal ablation area. No antibioticrophylaxis or antibiotic therapy has been shown to beffective in preventing this complication. It is difficult, how-ver, to consider patients without a functional sphincter of

ddi but who are also inoperable and have an absolute con-raindication for any percutaneous treatment, as this wouldemove the last possibility of curative treatment. The riskf percutaneous treatment may be taken in this situation

tocellular carcinoma treated by electroporation. Computed tomo-ss. One month after irreversible electroporation (with 4 electrodes)struction with no related biliary damage.

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Percutaneous hepatic ablation: What needs to be known in

provided that the patients are monitored very carefully inthe weeks after the procedure. Any abscess, which developsshould be treated promptly with drainage and appropriateantibiotic therapy.

Electromagnetic interferencesDelivering electromagnetic pulses close to a pacemakercan theoretically damage it. In practice, this applies withmonopolar RF and microwaves but not with bipolar RF (asin order for interference to develop, the pacemaker wouldneed to be located between the two active electrodes!).From this perspective, multipolar RF is the safest tech-nique. In reality, monopolar and microwave ablation maybe carried out in patients with pacemakers [31] although acardiology opinion is recommended before the procedure. Ifthe decision is made to continue, these patients should betreated under ad hoc resuscitation safety conditions. Elec-troporation which also uses bipolar mode but with very highRF intensities and potentials is, however, completely con-traindicated in heart disease (of any type) because of therisk of a serious arrhythmia (even if the RF pulses are onlydelivered during the ECG refractory period [S-T]).

Conclusion

The emergence of effective reproducible mini-invasive per-cutaneous treatments such as radiofrequency has profoundlychanged the management of small malignant liver tumorsfor which the only radical treatment until recently has beenexcision surgery. Outside of the transplantation situation,the first line treatment of early stages (TNM I) of HCCshould now be with percutaneous ablation techniques. Thereis a well-acknowledged lack of information in the litera-ture to establish the exact role of percutaneous methodsfor treatment of localized hepatic metastases, particularlythose from colorectal cancer compared to excision surgery.It does, however appear here again that percutaneous meth-ods can offer long-term survival, which is entirely similarto the survival obtained after hepatectomy. These still tooscarce findings should be followed by randomized trialsto compare percutaneous techniques with excision for thetreatment of metastases.

Combination treatments using percutaneous destructiontechniques and endarterial therapies have long been con-sidered to be the most promising strategies to improve andextend the indications for the percutaneous treatments.Considerable technological advances in recent years havebrought new future prospects for treatment. The second-generation microwave devices, which are far faster thanmonopolar radiofrequency ablation technically, enable com-plete treatment of 5 to 8 small (≤ 3 cm) liver tumors ina single session. Multipolar radiofrequency ablation canachieve controlled thermo-ablation of both small and largertumors (> 5 cm, < 8 cm), whether or not these are superficial.Irreversible electroporation now offers radical treatment

for central, inoperable liver tumors. These new treatmentmethods clearly need to be confirmed on a larger scalealthough the speed of technological change in the field ofablation is such that now even more than before our clinical

671

esearch must be permanently incorporated into our routinelinical practice.

linical case

57-year-old man followed up for Child-Pugh A 5 mixedost-HVC and alcoholic cirrhosis (the patient was still drink-ng) (PR 60%, Bilirubin 30 �g/mL) was found to have fourodules under 3 cm in diameter with (CT) appearancesf hepatocellular carcinoma. His alpha-fetoprotein was0 ng/mL (Fig. 6).

uestions

. What treatment would you consider?A. Transplantation.B. Excision.C. Chemoembolization.D. Ablation(s).

. Which of the ablation techniques do you think is mostappropriate?A. Multipolar radiofrequency ablation.B. Electroporation.C. Microwave.D. Conventional monopolar radiofrequency ablation.

. The lesions are not entirely visible on ultrasound:A. This is a contraindication to ablation techniques:

arterial chemoembolization therapy would be better.B. The ablation procedure should be performed under

CT guidance.C. The ablation procedure should be performed by flat

sensor angiography with cone beam CT guidance.D. Ultrasound guidance with pre-treatment CT or MR

guidance could be considered.. The repeat CT performed a month after treatment shows

a good response in the four lesions treated. Three monthslater, however, when the patent had stopped drinkingcompletely and his liver function had improved, threenew nodules were found. What do you propose? (Fig. 7):A. Chemoembolization.B. Radioembolization.C. Transplantation.D. A percutaneous ablation procedure.

nswers

. Answer D. A. Temporary contraindication to HT (thepatient has not stopped drinking). If the patientstopped his excessive alcohol consumption the aver-age transplant waiting time is 1 year for Child-PughA disease. He is slightly outside of the Milan crite-ria (tumors < 3 cm although number > 3). As a minimum,therefore, ‘‘holding’’ treatment should be offered. B:more than three segments contain tumor and active cir-rhosis is present. These represent a contraindication toexcision surgery. C. This is the treatment very often

recommended in this situation of multifocal HCC. It istherefore by necessity non-selective. The risk of deterio-ration of liver function after treatment is high in this casein an alcoholic patient who is still drinking. In addition,

672 O. Seror

Figure 6. Three computed tomography section levels in the arterial phase of contrast enhancement showing four hypervascular nodules( 3 cm

o ng).

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with wash-out in the portal phase not shown on the figure) under

f ascites indicating decompensated cirrhosis (alcoholic, still drinki

the effect of endarterial therapy is difficult to predictand rarely complete (it is a palliative treatment).

. Answer C and D (Fig. 8). A. The challenge in this situationis to control the disease as radically as possible withoutdeteriorating liver function. Multipolar RF achieves nearconstant average safety margins of 1 cm when the nod-ules are small, as they are in this case (< 3 cm). With 4tumors, however, a significant amount of functional liverparenchyma would be sacrificed. The benefit/risk bal-ance of multipolar RF does not therefore appear to bepositive in this case. B. This is a new technique, whichhas not been shown to be effective compared to the moreconventional methods such as RF or microwave. Elec-troporation is a reasonable method if thermotherapies(RF MW) are absolutely contraindicated, particularly forcentral, inoperable tumors juxtapositioned between thevascular convergence and common bile duct.

. Answer D. A. Fusion and virtual navigation technologieshave greatly improved guiding imaging in recent years.Lesions, which cannot be seen on ultrasound can nowbe located and treated in most cases using these tech-nologies. B. This is far more intensive, time consuming(human and machine), exposes the patient to irradia-tion (multiple nodules) and also inexact (poor contrastin the liver nodules without enhancement). C. Compared

to CT these new generation angiography tables are help-ful as they allow better patient accessibility. They alsohave rotational 3D (cone beam CT) guiding and fusion

in diameter. Note also the hepatic dysmorphism and small amount

instruments, which allow the difficultly located target tobe punctured. These low contrast images do in addition,however, deliver a relatively large amount of irradiation(high angular sampling of the RX beams for images withthe best tissue contrast).

. Answer C and D. A. This is an option, but why choosea treatment which is only partially effective and unpre-dictable when there are ‘‘only three’’ small lesions? B.This is a treatment currently being assessed, which hasnot been shown to be superior to chemoembolization. C.Yes, in this young patient who has stopped excessive alco-hol consumption. Transplant would seem at present thebest long-term treatment option. Local or locoregionaltreatments, even if effective, will not prevent the laterdevelopment of new lesions as this patient has evidenceof multicenter carcinogenesis. He is still however Child-Pugh stage A and his liver function has even improved,so a transplant waiting time of at least a year should beplanned. D. Percutaneous ablation is a perfectly appro-priate ‘‘holding’’ treatment pending transplantation. Italso has the advantage over chemoembolization of beingrepeatable almost without limit (as long as there arenot too many lesions) and being more radical. This issignificant, as transplantation remains a possibility forall patients on the list. There is of course a risk of

dissemination along the puncture path after percuta-neous treatment. This risk is sufficiently low, however,not to represent an absolute contraindication in patients

Percutaneous hepatic ablation: What needs to be known in 2014 673

Figure 7. Three computed tomography section levels in the arterial phase of contrast enhancement showing areas of destruction byapplication of microwave energy.

Figure 8. Strategy plan for multiple percutaneous ablations to reduce the number of punctures and length of the procedure.

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awaiting transplant. The risk is particularly low in ourpatient as none of the lesions to be treated are locatedbeneath the capsule.

isclosure of interest

he author declares that he has no conflicts of interest con-erning this article.

eferences

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