Contrast-enhanced ultrasonography for real-time monitoring of interstitial laser thermal therapy in the focal treatment of prostate cancer
DOI:
https://doi.org/10.5489/cuaj.1044Abstract
Introduction: We report a case study of the application of contrastenhanced
ultrasonography (CEUS) for intraoperative monitoring
of thermal ablation of a single focus of prostate cancer.
Methods: A patient presented with biopsy-proven, solitary-focus,
low-risk prostate cancer and was recruited into a clinical trial of
interstitial laser thermal focal therapy. Multiparametric magnetic
resonance imaging (MRI) was used to locate the single dominant
focus, and photothermal ablation was performed at the tumour
site under the guidance of transrectal ultrasonography. Transrectal
CEUS using systemic bolus injections of the intravascular contrast
agent Definity was performed immediately before, several times
during and on completion of therapy. Lesions observed on CEUS
were compared with treatment effect as measured by tissue devascularization
on 1-week gadolinium (Gd)–enhanced MRI.
Results: Baseline images showed CEUS contrast-agent signal
throughout the prostate. During and after treatment, large hypocontrast
regions were observed surrounding the treatment fibres, indicating
the presence of an avascular lesion resulting from photothermal
therapy. Lesion size was found to increase during the delivery
of thermal energy. Lesion size measured using CEUS (16 × 11 mm)
was similar to the 7-day lesion measured using Gd-enhanced
T1-weighted MRI.
Conclusion: Focal therapy for prostate cancer requires both complete
treatment of the dominant tumour focus and minimal morbidity.
The application of CEUS during therapy appears to provide
an excellent measure of the actual treatment effect. Hence, it can be
used to ensure that the therapy encompasses the whole target but
does not extend to surrounding critical structures. Future clinical
studies are planned with comparisons of intraoperative CEUS to
Gd-enhanced MRI at 7 days and whole-mount pathology samples.
Introduction : Nous décrivons un cas d’application de la technique
d’échographie de contraste pour la surveillance peropératoire pendant
l’ablation thermique d’un cancer de la prostate à foyer unique.
Méthodologie : Le patient présentait un cancer de la prostate à faible
risque et à foyer unique confirmé par biopsie et a été inscrit à
un essai clinique portant sur la thérapie thermique interstitielle
par laser. Après une épreuve d’IRM à paramètres multiples en vue
de localiser le foyer dominant unique, on a procédé à une ablation
photothermique guidée par échographie transrectale. On a
effectué une échographie transrectale à l’aide d’injections bolus
intravasculaires de l’agent de contraste Definity immédiatement
avant l’ablation, de même que plusieurs fois pendant l’intervention
et à la fin de celle-ci. Les lésions observées lors de l’échographie
de contraste ont été comparées à l’effet du traitement, tel que
mesuré par la dévascularisation tissulaire lors d’une épreuve d’IRM
avec injection de Gd une semaine plus tard.
Résultats : Les images initiales montrent le signal de l’agent de
contraste dans toute la prostate. Pendant et après le traitement, de
grandes zones d’hypocontraste ont été observées autour des zones
de traitement, indiquant la présence d’une lésion avasculaire
causée par la thérapie photothermique. La taille de la lésion s’est
accrue pendant la libération de l’énergie thermique. La taille de
la lésion, telle que mesurée par échographie de contraste (16 ×
11 mm) n’avait pas changé une semaine plus tard lors de l’épreuve
d’IRM T1 avec injection de Gd.
Conclusion : La thérapie focale appliquée à la prostate requiert le
traitement complet du foyer tumoral dominant et une morbidité
minimale. Le recours à l’échographie de contraste durant le traitement
semble un excellent moyen de mesurer l’effet réel du traitement.
On peut donc l’utiliser pour assurer que le traitement englobe
toute la zone cible sans s’étendre aux structures adjacentes.
D’autres études cliniques comparant les résultats à ceux de l’IRM
avec injection de Gd après 7 jours et des échantillons anatomopathologiques
in toto sont prévues.
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