FACTORS PREDICTING COMPLETE NECROSIS RATE AFTER PERCUTANEOUS US-GUIDED LASER THERMOABLATION OF HEPATOCELLULAR CARCINOMA NODULES=/<4 CM IN CIRRHOTIC PATIENTS. A MULTIVARIATE ANALYSIS

Purpose: Aim of the present study was to evaluate effectiveness of US-guided percutaneous laser thermal ablation (LTA) in the treatment of HCC nodules >/=4cm and predictive factors for complete necrosis

Methods and Materials: 86 HCC nodules (mean diameter 23.59mm; range 8–40mm) in 60 cirrhotic patients (mean age 68.3 yr; 36 males; 57 HCV+; 51 Child A and 9 Child B) were selected for LTA between January 2001 and December 2004. 51 nodules were newly diagnosed, 14 had been previously treated (PEI and/or TACE), and 19 represented intra (8 cases) or extra nodular (11 cases) relapses during follow-up after treatment. One to four 300µm optic fibre(s) advanced in 21-g needle(s) were positioned into the target lesions under US guide. LTA was performed with a continuous wave Nd:YAG laser operating at a wavelength of 1.064 nm (DEKA MELA, Florence, Italy). A single optimal laser illumination was considered when 1800 Joules/fibre were delivered in 6min. at 5 W. The interventional procedure was performed under conscious sedation, on an inpatient basis. Spiral bi- or triphasic CT and, more recently, contrast-enhanced US with Sonovue (Bracco, Milan, Italy) were used to verify treatment effectiveness after LTA completion. The association between characteristics of lesion and outcome (complete or incomplete necrosis) was evaluated through logistic regression taking into account the following predictive factors in different models: nodule size, pattern of growth (infiltrating or not) at imaging, location, first diagnosis of HCC, number of sessions (1/>1), total delivered energy, year/s of treatment (2001–2002 vs. 2003–2004).

Results: Complete necrosis was obtained in 62 nodules (72%). Statistically significant predictors of outcome at both univariata and multivariate analysis included: infiltrating growth pattern (OR=12.3), not nave nodules (OR=8.7 vs. nanve nodule), and year of treatment (years 2001–2002 OR=10.3 vs. years 2003–2004)

Conclusions: Completeness of necrosis after LTA of HCC nodules=/>4cm turned out to be significantly affected by operator's experience and skills and factors related to the neoplastic lesion, notably if it represented first diagnosis of HCC (nave nodule) and showed a not infiltrating pattern of growth at imaging