Jan 16, 2009 - Real-time monitoring of radiofrequency ablation of liver tumors using thermal-dose calculation by MR temperature imaging: initial results in ...
Eur Radiol DOI 10.1007/s00330-009-1532-1
INTERVENTIONAL
Matthieu Lepetit-Coiffé Hervé Laumonier Olivier Seror Bruno Quesson Musa-Bahazid Sesay Chrit T. W. Moonen Nicolas Grenier Hervé Trillaud
Real-time monitoring of radiofrequency ablation of liver tumors using thermal-dose calculation by MR temperature imaging: initial results in nine patients, including follow-up
Received: 16 January 2009 Accepted: 21 June 2009 # European Society of Radiology 2009
M.-B. Sesay Service d’Anesthésie Réanimation III, Hôpital Pellegrin, CHU Bordeaux, Bordeaux, France
M. Lepetit-Coiffé (*) . H. Laumonier . O. Seror . B. Quesson . C. T. W. Moonen . N. Grenier . H. Trillaud Laboratoire Imagerie Moléculaire et Fonctionnelle: de la physiologie à la thérapie CNRS UMR 5231, Université Victor Segalen Bordeaux 2, 146 rue Léo Saignat - Case 117, 33076 Bordeaux Cedex, France e-mail: matthieu.lepetit-coiffe@imf. u-bordeaux2.fr Tel.: +33-5-57574591 Fax: +33-5-57574597 H. Laumonier . H. Trillaud Service de Radiologie, Hôpital Saint-André, CHU Bordeaux, Bordeaux, France O. Seror Service de Radiologie, Hôpital Jean Verdier, Bondy, France
N. Grenier Service d’Imagerie Diagnostique et Thérapeutique de l’Adulte, Hôpital Pellegrin, CHU Bordeaux, Bordeaux, France
Abstract To assess the practical feasibility and effectiveness of real-time magnetic resonance (MR) temperature monitoring for the radiofrequency (RF) ablation of liver tumours in a clinical setting, nine patients (aged 49–87 years, five men and four women) with one malignant tumour (14–50 mm, eight hepatocellular carcinomas and one colorectal metastasis), were treated by 12-min RF ablation using a 1.5-T closed magnet for real-time temperature monitoring. The clinical monopolar RF device was filtered at 64 MHz to avoid electromagnetic
Introduction Over the last 10 years, radiofrequency (RF) ablation procedure has become a widely accepted treatment for small (≤5 cm) malignant primary [1] or metastatic [2] liver tumours. Currently, the most widespread imaging technique for monitoring RF ablation of liver tumours is ultrasonography (US). Unfortunately, the expansion of the transient hyperechogenic area observed during RF energy deposition does
interference. Real-time computation of thermal-dose (TD) maps, based on Sapareto and Dewey’s equation, was studied to determine its ability to provide a clear end-point of the RF procedure. Absence of local recurrence on follow-up MR images obtained 45 days after the RF ablation was used to assess the apoptotic and necrotic prediction obtained by real-time TD maps. Seven out of nine tumours were completely ablated according to the real-time TD maps. Compared with 45-day follow-up MR images, TD maps accurately predicted two primary treatment failures, but were not relevant in the later progression of one case of secondary local tumour. The real-time TD concept is a feasible and promising monitoring method for the RF ablation of liver tumours. Keywords Radiofrequency ablation . Magnetic resonance imaging . MR thermometry . Thermal dose . Interventional procedures
not strictly correspond to definite thermal tissue injuries [3]. The intraprocedural injection of US bubbles as a contrast agent can reveal residual unablated parts of the tumour and can thus allow the physician to perform additional RF applications to complete the ablation [4]. However, the effectiveness of intraprocedural US contrast imaging in detecting any possible residual tumour can be reduced by several parameters, such as tumour location or remnant hyperechogenic change as a result of RF deposition [5].
Computed tomography (CT) and magnetic resonance (MR) imaging with contrast agent injection are currently the best techniques to assess the treatment response to RF ablation [6]; however, due to post-RF peritumoral inflammatory changes, both must be performed a few weeks after the procedure. For temperature-based therapies such as RF ablation, it has been shown that a close relationship exists between cell death and the accumulated thermal dose (TD), which is dependent on both temperature increase and time of exposure [7]. Therefore, real-time MR temperature imaging covering the entire tumour and its surrounding area seems to be a relevant strategy for monitoring the RF ablation. MR temperature imaging based on the proton resonance frequency (PRF) technique has been shown to be a very promising approach for monitoring thermal ablation using laser [8] or high-intensity focused ultrasound [9]. More recently, MR thermometry has been successfully tested on animal models to monitor hepatic RF ablation, with the condition of the appropriate filtering of the RF generator output to suppress electromagnetic interference on the MR temperature images [10, 11]. The present study was designed to assess the practical feasibility and effectiveness of MR temperature monitoring of RF ablations of liver tumours in a clinical environment.
range 49–87 years) with one malignant tumour, underwent radiofrequency ablation under MR temperature monitoring (Table 1). The tumours treated were hepatocellular carcinomas (HCCs) (n=8) and colorectal metastasis (n=1) with sizes ranging between 5 and 28 mm along the short axis (median size of 18 mm) and between 14 and 50 mm along the long axis (median size of 18 mm). The selection criteria were: (1) a confirmed diagnostic of malignancy according to either histology or, for HCC, noninvasive criteria proposed by the European Association for the Study of the Liver (EASL) conference [12], (2) presence of a single tumour no larger than 5 cm in its maximal dimension, (3) absence of detectable tumoral vascular invasion, (4) ineligibility for surgical resection or transplantation, (5) insufficient visibility of the tumour(s) with ultrasound or unenhanced CT (6) prothrombin activity ≥50% and platelet count ≥50.103/ml. Patient positioning, anaesthesia and monitoring
This case series study was approved by the institutional review board of our hospital for each patient. All patients were included after oral informed consent as recommended by our institution. Between November 2004 and June 2006, nine patients, including five men and four women (median age: 56 years,
The patients with a four-element flexible receiver coil wrapped at the level of the liver were introduced feet first in a supine position into the tunnel of a 1.5-T magnet (ACSNT; Philips Medical Systems, Best, The Netherlands). General anaesthesia with tracheal intubation was used in all the patients. The protocol was standardised as follows: induction with propofol (Diprivan; AstraZeneca, RueilMalmaison, France) 1.5–2.5 mg/kg, remifentanil (Ultiva; GlaxoSmithKline, Marly-le-Roi, France)1 μg/kg and cisatracurium (Nimbex; GlaxoSmithKline, Marly-le-Roi, France) 0.15 mg/kg. Anaesthesia was maintained during the procedure with continuous infusion of propofol 6–12 mg/kg/min and remifentanil 0.25 μg/kg/min. The extubated patients were transferred to the intensive care unit. They were discharged 24 h later.
Table 1 Data synthesis of the nine patients included in the preliminary clinical study of RF ablation procedure performed under real-time temperature MR imaging (CEA carcinoembryonic
antigen serum level, F female, HCC hepatocellular carcinoma, HCV hepatitis C virus, M male, NA not available, NASH non-alcoholic steatohepatitis)
Materials and methods Patient selection, tumours
Patient Age Sex Tumour (year) histology
Child-Pugh Liver histology score
Anatomical location
1 2 3
50 69 49
M M F
A B NA
Alcoholic cirrhosis Segment III Alcoholic cirrhosis Junction II-IV Normal Segment VII
4
56
F
HCC HCC Colorectal metastasis HCC
A
5 6 7 8 9
87 52 51 74 71
F M F M M
HCC HCC HCC HCC HCC
B B NA B A
Alcoholic and HCV cirrhosis HCV cirrhosis Alcoholic cirrhosis NASH Alcoholic cirrhosis Unspecific cirrhosis
α-fetoprotein level (μg/l)
Tumour sizes Date of RF (mm×mm) ablation
