E. Berber et al., Use of CT Hounsfield unit density to identify ablated tumor after laparoscopic radiofrequency ablation of hepatic tumors, SURG ENDOSC, 14(9), 2000, pp. 799-804
Citations number
18
Categorie Soggetti
Surgery
Journal title
SURGICAL ENDOSCOPY-ULTRASOUND AND INTERVENTIONAL TECHNIQUES
Backguound: When attempting to interpret CT scans after radiofrequency ther
mal ablation (RFA) of liver tumors, it is sometimes difficult to distinguis
h ablated from viable tumor tissue. Identification of the two types of tiss
ue is specially problematic for lesions that are hypodense before ablation.
The aim of this study was to determine whether quantitative Hounsfield uni
t (HU) density measurements can be used to document the lack of tumor perfu
sion and thereby identify ablated tissue.
Methods: Liver spiral CT scans of 13 patients with 51 lesions undergoing la
paroscopic RFA for metastatic liver tumors within a 2-year time period were
reviewed. HU density of the lesions as well as normal liver were measured
pre- and postoperatively in each CT phase (noncontrast, arterial, portoveno
us). Statistical analyses were performed using Student's paired t-test and
ANOVA.
Results: Normal liver parenchyma, which was used as a control, showed a sim
ilar increase with contrast injection in both pre- and postprocedure CT sca
ns (56.4 +/- 2.4 vs 57.1 +/- 2.4 HU, respectively; p = 0.3). In contrast, a
blated liver lesions showed a preablation increase of 45.7 +/- 3.4 HU but o
nly a minimal postablation increase of 6.6 +/- 0.7 HU (p < 0.0001). This wa
s true for highly vascular tumors (neuroendocrine) as well as hypovascular
ones (adenocarcinoma).
Conclusions: This is the first study to define quantitative radiological cr
iteria using HU density for the evaluation of ablated tissues. A lack of in
crease in HU density with contrast injection indicates necrotic tissue, whe
reas perfused tissue shows an increase in HU density. This technique can be
used in the evaluation of patients undergoing RFA.