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Percutaneous Application of High Power Microwave Ablation With 150 W for the Treatment of Tumors in Lung, Liver, and Kidney: A Preliminary Experience

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Technology in Cancer Research & Treatment
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Objective: The aim of this study is to evaluate the feasibility, safety, and short-term effectiveness of a high-power (150 W) microwave ablation (MWA) device for tumor ablation in the lung, liver, and kidney. Methods: Between December 2021 and June 2022, patients underwent high-power MWA for liver, lung, and kidney tumors. A retrospective observational study was conducted in accordance with the Declaration of Helsinki. The MWA system utilized a 150-W, 2.45-GHz microwave generator (Emprint™ HP Ablation System, Medtronic). The study assessed technical success, safety, and effectiveness, considering pre- and post-treatment diameter and volume, lesion location, biopsy and/or cone beam computed tomography (CBCT) usage, MWA ablation time, MWA power, and dose-area product (DAP). Results: From December 2021 to June 2022, 16 patients were enrolled for high-power MWA. Treated lesions included hepatocellular carcinoma (10), liver metastasis from colon cancer (1), liver metastasis from pancreatic cancer (1), squamous cell lung carcinoma (2), renal cell carcinoma (1), and renal oncocytoma (1). Technical success rate was 100%. One grade 1 complication (6.25%) was reported according to CIRSE classification. Overall effectiveness was 92.8%. Pre- and post-treatment mean diameters for liver lesions were 19.9 mm and 37.5 mm, respectively; for kidney lesions, 34 mm and 35 mm; for lung lesions, 29.5 mm and 31.5 mm. Pre- and post-treatment mean volumes for liver lesions were 3.4 ml and 24 ml, respectively; for kidney lesions, 8.2 ml and 20.5 ml; for lung lesions, 10.2 ml and 32.7 ml. The mean ablation time was 48 minutes for liver, 42.5 minutes for lung, and 42.5 minutes for renal ablation. The mean DAP for all procedures was 40.83 Gcm2. Conclusion: This preliminary study demonstrates the feasibility, safety, and effectiveness of the new 150 W MWA device. Additionally, it shows reduced ablation times for large lesions.
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Percutaneous Application of High Power
Microwave Ablation With 150 W for the
Treatment of Tumors in Lung, Liver, and
Kidney: A Preliminary Experience
Carolina Lanza, MD
1
, Serena Carriero, MD
1
, Velio Ascenti, MD
1
,
Jacopo Tintori, MD
1
, Francesco Ricapito, MD
1
,
Roberto Lavorato, MD, PhD
2
, Pierpaolo Biondetti, MD, PhD
3,4
,
Salvatore Alessio Angileri, MD
3
, Filippo Piacentino, MD, PhD
5
,
Federico Fontana, MD
5,6
, Massimo Venturini, MD
5,6
,
Anna Maria Ierardi, MD
3
, and Gianpaolo Carraello, MD
3,4
Abstract
Objective: The aim of this study is to evaluate the feasibility, safety, and short-term effectiveness of a high-power (150 W)
microwave ablation (MWA) device for tumor ablation in the lung, liver, and kidney. Methods: Between December 2021 and
June 2022, patients underwent high-power MWA for liver, lung, and kidney tumors. A retrospective observational study was con-
ducted in accordance with the Declaration of Helsinki. The MWA system utilized a 150-W, 2.45-GHz microwave generator
(EmprintHP Ablation System, Medtronic). The study assessed technical success, safety, and effectiveness, considering pre-
and post-treatment diameter and volume, lesion location, biopsy and/or cone beam computed tomography (CBCT) usage,
MWA ablation time, MWA power, and dose-area product (DAP). Results: From December 2021 to June 2022, 16 patients
were enrolled for high-power MWA. Treated lesions included hepatocellular carcinoma (10), liver metastasis from colon cancer
(1), liver metastasis from pancreatic cancer (1), squamous cell lung carcinoma (2), renal cell carcinoma (1), and renal oncocytoma
(1). Technical success rate was 100%. One grade 1 complication (6.25%) was reported according to CIRSE classication. Overall
effectiveness was 92.8%. Pre- and post-treatment mean diameters for liver lesions were 19.9 mm and 37.5 mm, respectively; for
kidney lesions, 34 mm and 35 mm; for lung lesions, 29.5 mm and 31.5 mm. Pre- and post-treatment mean volumes for liver
lesions were 3.4 ml and 24 ml, respectively; for kidney lesions, 8.2 ml and 20.5 ml; for lung lesions, 10.2 ml and 32.7 ml. The
mean ablation time was 48 minutes for liver, 42.5 minutes for lung, and 42.5 minutes for renal ablation. The mean DAP for all
procedures was 40.83 Gcm
2
.Conclusion: This preliminary study demonstrates the feasibility, safety, and effectiveness of the
new 150 W MWA device. Additionally, it shows reduced ablation times for large lesions.
Keywords
microwave ablation, high power, 150 W, lung, liver, kidney, tumor, thermal ablation
Abbreviations
CA, cryoablation; CBCT, cone-beam CT; DAP, dose area product; MWA, microwave ablation; RFA, radiofrequency ablation; US,
ultrasound; PNX, pneumothorax
Received: August 11, 2022; Revised: November 27, 2022; Accepted: June 7, 2023.
1
Postgraduate School in Radiodiagnostics, Università degli Studi di Milano, Milan, Italy
2
Diagnostic and Interventional Radiology Department, IRCCS CaGranda Fondazione Ospedale Maggiore Policlinico, Milan, Italy
3
Diagnostic and Interventional Radiology Department, IRCCS Granda Fondazione Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
4
Department of Health Science, Università degli Studi di Milano, Milano, Italy
5
Diagnostic and Interventional Radiology Unit, ASST Settelaghi, Varese, Italy
6
Insubria University, Varese, Italy
Corresponding Author:
Velio Ascenti, Postgraduate School in Radiodiagnostics, Università degli Studi di Milano, 20122 Milan, Italy.
Email: velio.ascenti@unimi.it
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(https://creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission pro-
vided the original work is attributed as specied on the SAGE and Open Access page (https://us.sagepub.com/en-us/nam/open-a ccess-at-sage).
New tools in loco-regional treatments: state of art and future directions Original Article
Technology in Cancer Research &
Treatment
Volume 22: 1-11
© The Author(s) 2023
Article reuse guidelines:
sagepub.com/journals-permissions
DOI: 10.1177/15330338231185277
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Introduction
Over the years multiple loco-regional techniques have been
developed including thermal and non-thermal ablation.
15
Thermal ablation techniques include heat-based thermal
ablations, such as radiofrequency ablation (RFA) and micro-
wave ablation (MWA) and cold-based thermal ablations, such
as cryoablation (CA).
6,7
Although RFA is still the most widely used ablation tech-
nique worldwide, throughout the years MWA has gained a lot
of interest proving to be an effective technique, equal or even
superior to RFA in some cases.
512
Among advantages of MWA over RFA there are: shorter time
of treatment, higher intra-tumoral temperatures, larger area of
necrosis and less effectiveness by the heat-sink effect.
8,10,13,14
The basic microwave system consists of three components: a
generator, a power distribution system and antennas.
1518
The
generator operates in the 915 MHz and 2.45 GHz frequency
bands to directly heat tissue to lethal temperatures greater
than 150 °C through dielectric hysteresis.
1921
Dielectric hys-
teresis is a process in which polar molecules, mainly water,
are forced to continuously realign themselves with the oscillat-
ing electric eld. This results in the generation of kinetic energy
and the consequent generation of heat.
4,18,22
In other words, MWA is a method of thermal tumor ablation
where tumors are heated to damage the structure and proteins of
the cell. As tumors have often a high water content, the micro-
waves induce rapid heating thanks to the interaction with the
polar water molecules within the tumor cells.
23
With regard to percutaneous ablations, data in literature
show a large collection of studies concerning systems operating
at a maximum power of 100 W.
24
As far as we know there are only few studies that demon-
strate the safety and efciency in vivo of systems operating at
140 W.
4,17,2527
Recently has been developed a new system that can generate
up to 150 W of power. Berber and Akbulut
10
published the rst
worldwide experience with this device, which they used only
laparoscopically or in open surgery to ablate liver tumors.
We report our initial experience to evaluate the feasibility,
safety and short-term effectiveness of this new ablation
device used percutaneously to ablate tumors in lung, liver and
kidney.
To our knowledge this is the rst experience that reports the
percutaneous employ of this ablation device.
Materials and Methods
Patients
Between December 2021 and June 2022 all patients were
enrolled for high-power MWA.
MWA was applied to liver, lung and kidney.
Written informed consent was obtained from all patients.
The study was conducted in accordance with the Declaration
of Helsinki, and the protocol was approved by the Ethics
Committee of IRCCS CaGranda Policlinico di Milano
(Project identication code: OSMAMI-23/05/2023-002
1942-U).
The reporting of this study conforms to STROBE
guidelines.
28
Diagnosis was made on the basis of imaging, medical history
and in some cases on biopsy.
Indications to MWA were shared by clinicians, surgeons and
interventional radiologists according to different selection crite-
ria, tailored to the specic abdominal diseases and according to
standard guidelines.
24
Patients undergoing anticoagulant and/or antiaggregant
therapy interrupted the treatment following the current guide-
lines, with the introduction of fractionated heparin when neces-
sary.
29,30
Uncorrectable coagulopathy was the only absolute
contraindication to the procedure.
All patientsdetails were de-identied for this study and the
patients were selected consecutively.
Pre-Treatment Procedure
Pre-treatment imaging consisted of multidetector computed
tomography (CT) using a 64-slice CT scanner (Philips,
Netherlands) and/or magnetic resonance using a 1.5-T scanner
(Siemens, Germany).
Before the beginning of each procedure, local anesthesia of
the antenna entrance site was achieved with 10-ml solution of
2% lidocaine.
Each patient was kept in a state of moderate sedation through
intravenous administration of a combination of midazolam
(0.07-0.08 mg/kg), propofol (0.5-2.0 mg/kg/h), and fentanyl
(1-2 μg/kg), which was mild during the antenna placement
and slightly stronger during the ablation.
Heart rate, electrocardiographic trace, oxygen saturation,
respiratory frequency and blood pressure were continuously
monitored throughout the procedure.
Adequate antibiotic prophylaxis was achieved with intrave-
nous administration of 2 g of cefazolin sodium (Ancef,
SmithKline Beecham Pharmaceuticals, Philadelphia, USA)
shortly before the procedure.
Procedure
The ablation system device used consisted of a microwave gen-
erator (EmprintHP Ablation System, Medtronic) capable of
producing 150 W of power at 2.45 GHz, connected by coaxial
cable to a 13-gauge straight microwave antenna with a length of
15 cm or 20 cm. The antenna was continuously perfused with
saline solution to prevent over-heat.
Patients were placed in the supine, prone or oblique position
and ultrasound (US) with or without the additional use of cone-
beam CT (CBCT) guidance or a CBCT only were performed to
choose the safest insertion of antenna.
In some cases, we used CBCT-derived volumetric data fused
with pre-procedural cross-sectional imaging and combined with
dedicated software for needle trajectory planning and ablation
2Technology in Cancer Research & Treatment
volume prediction. We used as navigational software,
Xperguide (Philips Allura Xper FD20; Philips Healthcare,
Best, Netherlands) for needle trajectory planning, and
XperCT (Philips Allura Xper FD20; Philips Healthcare, Best,
Netherlands), for the ablation volume prediction.
The generators output was moved straight up to 150 W
from the beginning, avoiding a gradual increase of power, at
a continuous wave of 2.45 GHz. The total ablation time was
variable tailored to the dimensions of the target lesion, to
obtain an optimal necrosis volume.
The cauterization of the needle tract after ablation was per-
formed to reduce the risk of seeding of the needle tract and
the risk of hemorrhages.
In some cases of high-power MWA we performed a post-
procedural CBCT to exclude the presence of immediate
complications.
After ablation, patients were transferred to the radiology
recovery room for observation. At 1 hour from the procedure,
all patients submitted to liver and kidney MWA underwent to
abdominal US and all patients submitted to lung MWA under-
went to chest X-ray.
Follow-Up
Each patient was scheduled to undergo follow-up at 1 month
after the procedure with multidetector CT using a 64-slice CT
scanner (Philips, Netherlands) before and after medium contrast
injection.
1
Outcomes Measures
The established outcomes for this study were technical success,
safety and effectiveness of the technique.
Technical success was dened as the correct positioning of
the antennae within the lesion, evaluated by intra-procedural
US/CBCT.
Safety was dened as the frequency of intraoperative, periop-
erative and delayed complications.
All complications were recorded and classied on a scale
from 1 to 6 according to the CIRSE Classication System For
Complications.
30,31
Effectiveness of the technique was dened as the absence of
imaging signs suggestive of residual or recurrence disease.
The parameters used to evaluate the effectiveness of the tech-
nique were dened on the basis of the lesions site in an organ-
specic fashion:
Liver lesions: the effectiveness of the technique was
dened as the absence of intra-tumoral (ie, non-rim-like)
arterial enhancement on contrast-enhanced CT or MRI.
Renal lesions: the effectiveness of the technique was
dened adequate if the follow-up imaging did not
show signicant enhancement (<15 HU) inside the
treated zone after contrast injection. Replacement of
the ablated parenchyma by necrosis was considered as
a positive predictive factor of treatment success.
3234
Lung lesions: the effectiveness of the technique was
dened, after 1 month, as the absence of any signicant
enhancement of the ablation zone on contrast enhanced
CT scan.
3537
For each case we have also evaluated multiple other parameters:
pre-treatment diameter, volume and location of the lesion,
usage of biopsy and/or CBCT before ablation, MWA ablation
time, MWA power and total Dose area product (DAP). We
also evaluated the post-operative ablation volume and diameter
of treated lesions.
Statistical Analysis
Descriptive analysis was performed on the dataset and pre-
sented in simple frequencies, proportion and percentages
using Microsoft Excel 2020 (Microsoft Corporation,
Redmond, WA, USA). The statistical analyses and the graph
were performed using Graph-Pad Prism software (Version 6;
GraphPad, Inc., San Diego, CA, USA).
Results
Patients
Between December 2021 and June 2022, 16 patients (11 males
and 5 females ranging in age between 64 and 83 years, mean
age 72.5) were enrolled for high-power MWA.
Pre-Procedural Data
In 10 of 16 patients, pre-treatment imaging consisted of contrast
enhanced CT, instead in 6 of 16 patients the pre-treatment
imaging consisted of contrast enhanced MRI.
The lesions treated were the follows: hepatocellular carci-
noma (HCC) (10), liver metastasis from colon cancer (1),
liver metastasis from pancreas cancer (1), squamous cell lung
carcinoma (2), renal cell carcinoma (1) and renal oncocytoma
(1). (Table 1) (Figures 14)
Pre-intervention biopsy was performed for all 2 renal
lesions, for all 2 lung lesions and for 2 hepatic lesions. The his-
tological results were the follows: renal cell carcinoma (1),
oncocytoma (1), hepatocellular carcinoma (1) metastases from
colon cancer (1), squamous cell lung carcinoma (2).
The mean diameter was considered for each organ like the
average of the largest one evaluated on any axis.
The pre-treatment mean diameter of treated lesions was
19.9 mm (range 10-38 mm) for liver lesions, 34 mm for
kidney lesions (range 30-38 mm) and of 29.5 mm for lung
lesions (range 23-36 mm).
Hepatic lesions are located both in right and left hepatic lobe,
precisely: in S8 (6 lesions, range 14-20 mm, average 17 mm), in
S7 (2 lesions, range 18-30 mm, average 24 mm), in S4 (2
lesions, range 26-30 mm, average 28 mm), in S3 (1 lesion,
9 mm), and in S2 (1 lesion, 20 mm).
Lanza et al 3
Two lung lesions were in the upper right lobe and in upper
left lobe.
The renal lesion was located into the middle portion of right
kidney.
The pre-treatment mean volume of the treated lesion was
3.4 mL (range 0.8-8.4 mL) for liver lesions, 8.2 mL for
kidney lesions (range 5.8-10.7 mL), and 10.2 mL for lung
lesions (range 4.9-15.5 mL).
Procedure
All procedures were conducted by a percutaneous
approach.
The mean time required to perform a complete procedure
was of 48 minutes for liver ablation (range 25-70 minutes); of
42.5 minutes for lung ablation (range 40-45 minutes) and of
42.5 minutes for renal ablation (range 35-50 minutes).
Figure 1. 150 W microwave ablation (MWA) of HCC in SVIII in a 70-year-old man. (A) arterial (B) venous and (C) delayed phase on CECT
show the presence of nodule of HCC 12 mm of maximus axial diameter (white arrow). (D) Intra-procedural CBCT shows the correct placement of
antenna and MWA at 150 W for 6 minutes was performed. 1-month CECT follow-up on (E) arterial, (F) portal and (G) delayed phase show a
hypodense area of thermocoagulation in all phases without residual disease. Abbreviations: CBCT, cone-beam CT; CECT, contrast-enhanced CT;
HCC hepatocellular carcinoma; MWA, microwave ablation.
Table 1. Histogram Chart Showing the Number and Location of Treated Lesions.
4Technology in Cancer Research & Treatment
The generator produced 150 W of power for an average time
of 3.5 minutes in the liver, 5.15 minutes for the lung and
4.65 minutes for kidney.
All procedures were performed with a power of 150 W.
We used in 9 cases (all cases of kidney and lung ablation and 7
cases of liver ablation) CBCT and navigational softwares such as
Xperguide (Philips Allura Xper FD20; Philips Healthcare, Best,
Netherlands) for needle trajectory planning, and XperCT (Philips
Figure 2. 150 W microwave ablation (MWA) of renal carcinoma in a 74-year-old man. (A) Arterial phase, (B) venous phase and (C) delayed
phase on CECT show a 32 ×27 mm of diameter lower polar right renal lesion. (D) Renal biopsy was performed with a histological diagnosis of
clear cell renal carcinoma. (E, F) Intra-procedural CBCT shows the correct placement of antenna and MWA at 150 W for 4 minutes was
performed. (G) Arterial, (H) portal and (I) delayed phase of 1-month CECT show lack of enhancement in the mass; (J) axial and (K) coronal
CBCT images using navigational softwares, Xperguide (Philips Allura Xper FD20; Philips Healthcare, Best, Netherlands) for needle trajectory
planning, and XperCT (Philips Allura Xper FD20; Philips Healthcare, Best, Netherlands), for the ablation volume prediction. Abbreviations:
CBCT, cone-beam CT; CECT, contrast-enhanced CT; HCC hepatocellular carcinoma; MWA, microwave ablation.
Lanza et al 5
Allura Xper FD20; Philips Healthcare, Best, Netherlands), for the
ablation volume prediction (Figures 2 and 4).
The mean DAP for all procedures was 40.83 Gcm
2
.
Follow-Up
Follow-up imaging consisted of contrast enhanced CT at 1
month after the procedure.
Out of 16 patients, 14 had a 1-month follow-up, 2
were lost (one renal oncocytoma and one HCC)
andtheremaining3hadbeentreatedfromlessthana
month.
The post-treatment mean diameter of the treated lesions
was 37.5 mm for liver lesions (range 20-44 mm), 35 mm
for kidney lesion and 31.5 mm for lung lesions (range
26-37 mm).
Figure 3. 150 W microwave ablation (MWA) of pulmonary lesions in 82-year-old man. (a) Pre-procedural CT scan and (B) pre-procedural
CT-PET show a left upper lobe metastatic lesion measuring 40 ×32 mm in greatest axial diameters with FDG uptake. (C) CT scan shows a single
antenna, which was positioned with CT guidance into the center of the lesion; 4 minutes at 150 W MWA was performed. (D) The patient suffered
a pneumothorax with an air leak that not required chest tube insertion. (E, F) Contrast-enhanced CT scans obtained at 1-month follow-up show an
enlargement of consolidation area, with intralesional cavitation and no enhancement uptake. Abbreviations: CBCT, cone-beam CT; CECT,
contrast-enhanced CT; computed tomography-positron emission tomography (CT-PET); HCC hepatocellular carcinoma; F-uorodeoxyglucose
(FDG);MWA, microwave ablation.
6Technology in Cancer Research & Treatment
Figure 4. 150 W microwave ablation (MWA) of residual hepatic lesion after loco-regional treatment in S4a. (A) Arterial, (B) venous, (C)
delayed phase show CECT show a contrast enhanced residual liver lesion with wash-out in venous and in delayed phases. (D) Intra-procedural US
guidance during the insertion of MWA antenna. (E) Axial, (F) coronal, (G) sagittal plans imaging-fusion between intra-procedural CBCT and
previous CECT, using navigational softwares, Xperguide (Philips Allura Xper FD20; Philips Healthcare, Best, Netherlands) for needle trajectory
planning, and XperCT (Philips Allura Xper FD20; Philips Healthcare, Best, Netherlands), for the ablation volume prediction. (H) Arterial, (I)
venous, and (J) delayed phases at 1-month CT follow-up, showing a complete response with the evidence of the coagulation zone. Abbreviations:
MWA, microwave ablation; CBCT, cone-beam CT; CECT, contrast-enhanced CT; HCC hepatocellular carcinoma.
Lanza et al 7
The post-treatment mean volume of the treated lesions was
24 mL for liver lesion (range 8-40 mL), 20.5 mL for kidney
and 32.7 mL for lung lesions (range 13.1-52.3 mL).
Outcome Measures
Technical Success. Technical success was 100%, with antenna
correctly placed within the lesion in all 16 cases.
Correct positioning of the antenna was conrmed with
CBCT in 10/16 lesions, with the remaining of the lesions con-
rmed with US only.
Safety. In our study population did not showed signicant com-
plications and only two grade 1 complication (12,5%) were
reported according to CIRSE classication.
The rst was a case of mild endoalveolar hemorrage detected
on post-procedural CBCT, consequent to lung thermoablation,
which did not make it necessary to add additional therapy; the
second was a small pneumothorax (PNX) in the same patient,
that not needed of insertion of drainage tube (Figure 1).
Both lesions were adherent to the pleura and did not cause
ablation of the ribs or great vessels; ablation of the smaller
lesion caused a clinically silent saccular effusion with super-
uid density detected on follow-up CT scan at 1 month.
Effectiveness of the Technique. As previously discussed, the
effectiveness of the technique was dened as the absence of
early imaging signs suggestive of residual and/or recurrence
disease and was evaluated in a different way for each organ tar-
geted. These goals were achieved in all procedure except in one
case of HCC where was observed a residual of disease of
20 mm at 1-month CT follow-up.
In our study:
10 out of 11 (90.9%) of liver lesions did not show
rim-like intra-tumoral enhancement at 1-month
follow-up imaging.
1 out of 1 (100%) of renal lesions did not show signi-
cant intra-tumoral enhancement at 1-month follow-up
imaging.
2 out of 2 (100%) of lung lesions did not show signi-
cant intra-tumoral contrast uptake at 1-month follow-up
imaging.
The total effectiveness assessed by our study was therefore
92.8% (13 out of 14) (Table 2).
Discussion
Several types of ablation devices can be used in the eld of
interventional oncology, these include both thermal and non-
thermal techniques.
38
RFA and MWA are both hyperthermic procedures that apply
energy in order to heat tissues until they reach lethal tempera-
tures. MWA has several other advantages of other ablation tech-
niques, in particular rather than RFA, including: higher
intra-tumoral temperatures, larger tumor ablation volumes,
faster ablation times, ability to use simultaneously multiple
applicators, optimal heating of cystic masses and tumors close
to the vessels for its less susceptibility to heat sink effect.
39
Another considerable difference between MWA and RFA is
that, since all antennas are bipolar by denition, there is no
need of neutral electrodes applied to the patient, ruling out
skin burns at the grounding pad site, one of the possible compli-
cations of RFA treatments.
MWA heat-generating capabilities depend upon electromag-
netic radiation, causing a fast switching rotation at atomic or
molecular levels of electric dipoles such as polar molecules
(eg H
2
O), causing heating by friction of water molecules.
Temperatures higher than 100 °C and tissue carbonization are
not limiting the MW heating process, allowing for large coag-
ulation zones, less susceptibility to the heat sinking effects
and higher temperatures in general.
40
With the advancement of microwaves ablative techniques,
several new innovations in this eld of application have been
introduced: the achieving of a real predictable ablation area,
using the thermosphere technology, which leads to eld
control, thermal control and wavelength control to maintain a
precise, predictable and spherical ablation zone throughout pro-
cedures; the application of increasing power systems, until
150 W, with a production of large zone of ablation in short
time.
22
In the present study we report the rst experience of percu-
taneous application of 150 W system for the MWA in different
clinical applications, including liver, lung and kidney lesions.
Considering the clinical outcome of the whole population,
our ndings were globally satisfactory in terms of technical
Table 2. Efcacy Rate of the Technique at 1-Month CT Follow-Up for Treated Lesions at the Various
Sites.
8Technology in Cancer Research & Treatment
success, the effectiveness of the technique, and recorded
complications.
Although preliminary, the data from our cases conrm the
aforementioned experimental studies, demonstrating the ef-
cacy of percutaneous ablation of lesions with high-power
system (150 W), achieving a large diameter of ablation (more
than 3 cm) with a single antenna and in short times without sig-
nicant complications.
Thus, comparing with 100 W ablation system, the high-power
ablation systems lead to a large ablation area using a single antenna
whereas the necessity to use 2 antennas with consequent lower
costs. Furthermore, the use of a single antenna rather than
double, ensures a more predictable and spherical ablation area.
In our series, only one case of intra-alveolar hemorrhage fol-
lowing ablation in the lung was reported, without post-
procedural sequelae and deviation from the normal post-
therapeutic course (grade 1).
Hines-Peralta et al
41
evaluated the rationale of using probes
with power greater than 100 W. In ex vivo and in vivo studies
on animal livers, demonstrating how the use of high-powered
antennas produces large zones of coagulation in shorter time,
in accordance with our study. In comparison to this study, we
performed all procedure in vivo humans including multiple
tumor diseases.
Berber and Akbulut
10
published the rst worldwide experi-
ence with 150 W ablation system, which they used only lapa-
roscopically or in open surgery to ablate liver tumors.
In confront to this study, we performed all procedures by a
percutaneous approach with its acknowledged minimally inva-
siveness. Furthermore, we used this new ablation system not
only for liver lesions, but for different abdominal and thoracic
lesions, including liver, lung, and kidney.
The generators output was moved straight up to 150 W
from the beginning, avoiding a gradual increase of power, at
a continuous wave of 2.45 GHz, without signicant recorded
complications.
Conclusions
In conclusion, our preliminary experience demonstrates that
this new 150 W MW device is feasible, safe and effective.
This system also has been shown a short time of ablation
time for the treatment of large lesions.
Limited number of patients and short-term follow-up repre-
sent the main limitations of our study and additional larger case
series with medium and long-term follow-up will be needed to
conrm these preliminary data.
The study was conducted in accordance with the Declaration of
Helsinki, and the protocol was approved by the Ethics Committee
of IRCCS CaGranda Policlinico di Milano (Project identication
code: OSMAMI-23/05/2023-0021942-U).
Declaration of Conicting Interests
The author(s) declared no potential conicts of interest with respect to
the research, authorship, and/or publication of this article.
Funding
The author(s) received no nancial support for the research, author-
ship, and/or publication of this article.
ORCID iDs
Carolina Lanza https://orcid.org/0000-0002-8286-1562
Velio Ascenti https://orcid.org/0000-0001-8041-4075
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... Depending on the tumor localization, size, and metastatic stage, treatment options in specialized clinics may include surgery, chemotherapy, radiation therapy, hormone therapy, bone marrow transplantation, targeted therapy, and immunotherapy [1]. For smaller tumors, at early stages, thermal ablation offers a low-risk and minimally invasive solution [2,3]. Nevertheless, despite all the academic and industry efforts, we still do not have an efficient answer to cancer, suggesting the need for a novel approach. ...
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Background: Contrasting data are available in the literature regarding the superiority of percutaneous microwave ablation (MWA) or radiofrequency ablation (RFA) in very early or early (BCLA 0 or A) hepatocellular carcinoma (HCC). Aims: The primary outcome was to compare the efficacy of RFA and MWA in achieving complete response in cirrhotic patients with early and very early HCC. The secondary outcomes were to evaluate the overall survival and the recurrence rate. Methods: A retrospective, observational, single-center study was performed. Inclusion criteria were liver cirrhosis, new diagnosis of a single node of HCC measuring a maximum of 50 mm or up to three nodules with diameter up to 35 mm, treatment with RFA or MWA. Radiological response was evaluated with multiphasic contrast-enhanced Computed Tomography or Magnetic Resonance Imaging at 5-7 weeks after thermal ablation. Complete response was defined when no vital tissue was detected after treatment. Results: Overall, 251 HCC patients were included in this study; 81 patients were treated with MWA and 170 with RFA. The complete response rate was similar in MWA and RFA groups (out of 331 nodules, 87.5% (91/104) were treated with MWA and 84.2% (186/221) were treated with RFA, p = 0.504). Interestingly, a subanalysis demonstrated that for 21-35 mm nodules, the probability to achieve a complete response using MWA was almost 5 times higher than for RFA (OR = 4.88, 95% CI 1.37-17.31, p = 0.014). Moreover, recurrence rate in 21-35 mm nodules was higher with RFA with respect to MWA (31.9% versus 13.5%, p = 0.019). Overall survival was 80.4% (45/56) when treated with MWA and 62.2% (56/90) when treated with RFA (p = 0.027). No significant difference was observed between MWA and RFA treatment in the 15-20 mm nodules group. Conclusion: This study showed that MWA is more efficient than RFA in achieving complete response in HCC nodules with 21 to 35 mm diameter.
Article
Background Regrowth after ablation is common, but predictive factors for local control are scarce. This study investigates whether histopathological growth patterns (HGP) can be used as a predictive biomarker for local control after ablation of colorectal liver metastases (CRLM). Methods Patients who received simultaneous resection and ablation as first treatment for CRLM between 2000 and 2019 were considered eligible. HGPs were determined on resected CRLM according to international guidelines and were classified as desmoplastic or non-desmoplastic. As minimal inter-tumour heterogeneity has been demonstrated, the HGP of resected and ablated CRLM were presumed to be identical. Local tumour progression (LTP) was assessed on postoperative surveillance imaging. Uni- and multivariable competing risk methods were used to compare LTP. Results In total 221 patients with 458 ablated tumours were analysed. A desmoplastic HGP was found in 60 (27.1%) patients who had a total of 159 (34.7%) ablated lesions. Five-year LTP [95%CI] was significantly higher for ablated CRLM with a presumed non-desmoplastic HGP (37% [30-43] vs 24% [17-32], Gray’s-test p=0.014). On multivariable analysis, a non-desmoplastic HGP (adjusted HR [95%CI]; 1.55 [1.03-2.35]) was independently associated with higher LTP rates after ablation. Discussion HGP is an independent predictor of local tumour progression following ablation of CRLM.
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Background and Objectives Data in literature regarding liver microwave ablation pertain to systems delivering 100 W of maximum power. Our aim is to assess a new 150 W microwave system for liver tumor ablation. Methods This was an institutional review board-approved study of patients undergoing ablation of malignant liver tumors using a 150 W microwave system. Feasibility, safety, ablation algorithm, perioperative outcomes, and efficacy were analyzed. Comparison was made to historical patients undergoing ablation using a 100 W microwave system. Results There were 33 patients with 76 malignant liver lesions who underwent ablation with the 150 W system. Using a step-wise algorithm, ablations without intraoperative complications were performed for tumors ranging in size from 0.3 to 6.7 cm. Ninety-day morbidity was 5%, with no mortality. Compared to the 100 W system, the 150 W system shortened ablation time and created larger ablation zones with a single stick. Conclusion This first worldwide experience showed that surgical ablations could be safely created at 150 W using a step-wise algorithm with complete tumor destruction achieved at short-term follow-up. Advantages versus 100 W systems include reduction in ablation time and creation of larger ablation zones with a single stick.
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This CIRSE Standards of Practice document is aimed at interventional radiologists and provides best practices for peri-operative anticoagulation management during interventional radiology procedures.