Ablation therapy of hepatocellular carcinoma: a comparative study between radiofrequency and microwave ablation.

PURPOSE: The aim of the study is to retrospectively evaluate and compare the therapeutic response of Radiofrequency (RF) and Microwave (MW) ablation therapy of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: 53 consecutive patients (42 males, 11 females; mean age 59 years, range: 40-68, SD: 4.2) underwent CT-guided percutaneous RF and MW ablation of 68 HCC liver lesions. The morphologic tumor response (number, location and size) was evaluated by magnetic resonance imaging. The follow-up protocol was 24 h post-ablation then within 3 monthly intervals post-ablation in the first year and 6 monthly intervals thereafter. RESULTS: Complete therapeutic response was noted in 84.4% (27/32) of lesions treated with RFA and in 88.9% (32/36) of lesions treated with MW ablation (P = 0.6). Complete response was achieved in all lesions ≤2.0 cm in diameter in both groups. There was no significant difference in rates of residual foci of HCC lesions between RF and MW ablation groups (P = 0.15, Log-rank test). Recurrence rate for 3, 6, 9, and 12 months in patients with HCC who underwent RF ablation compared with MW ablation were 6.3%, 3.1%, 3.1% versus 0%, 5.6%, 2.8%, and 2.8%. Progression-Free Survival rates for treated patients with RF ablation of 1, 2, and 3 years were 96.9%, 93.8%, and 90.6% and treated with MW ablation therapy were 97.2%, 94.5%, and 91.7, respectively (P = 0.98). CONCLUSION: In conclusion, RF and MW ablation therapy showed no significant difference in the treatment of HCC regarding the complete response, rates of residual foci of untreated disease, and recurrence rate.

Thermal ablation of liver metastases from colorectal cancer: radiofrequency, microwave and laser ablation therapies.

Surgery is currently considered the treatment of choice for patients with colorectal cancer liver metastases (CRLM) when resectable. The majority of these patients can also benefit from systemic chemotherapy. Recently, local or regional therapies such as thermal ablations have been used with acceptable outcomes. We searched the medical literature to identify studies and reviews relevant to radiofrequency (RF) ablation, microwave (MW) ablation and laser-induced thermotherapy (LITT) in terms of local progression, survival indexes and major complications in patients with CRLM. Reviewed literature showed a local progression rate between 2.8 and 29.7 % of RF-ablated liver lesions at 12-49 months follow-up, 2.7-12.5 % of MW ablated lesions at 5-19 months follow-up and 5.2 % of lesions treated with LITT at 6-month follow-up. Major complications were observed in 4-33 % of patients treated with RF ablation, 0-19 % of patients treated with MW ablation and 0.1-3.5 % of lesions treated with LITT. Although not significantly different, the mean of 1-, 3- and 5-year survival rates for RF-, MW- and laser ablated lesions was (92.6, 44.7, 31.1 %), (79, 38.6, 21 %) and (94.2, 61.5, 29.2 %), respectively. The median survival in these methods was 33.2, 29.5 and 33.7 months, respectively. Thermal ablation may be an appropriate alternative in patients with CRLM who have inoperable liver lesions or have operable lesions as an adjunct to resection. However, further competitive evaluation should clarify the efficacy and priority of these therapies in patients with colorectal cancer liver metastases.

Temperature imaging of laser-induced thermotherapy (LITT) by MRI: evaluation of different sequences in phantom.

The purpose of this study was to evaluate magnetic resonance (MR) temperature imaging of the laser-induced thermotherapy (LITT) comparing the proton resonance frequency (PRF) and T 1 thermometry methods. LITT was applied to a liver-mimicking acrylamide gel phantom. Temperature rise up to 70 °C was measured using a MR-compatible fiber-optic thermometer. MR imaging was performed by a 1.5-T scanner utilizing fast gradient echo sequences including a segmented echo planar imaging (seg-EPI) sequence for PRF and the following sequences for T 1 method: fast low-angle shot (FLASH), inversion recovery turbo flash (IRTF), saturation recovery turbo flash (SRTF), and true fast imaging (TRUFI). Temperature-induced change of the pixel values in circular regions of interest, selected on images under the temperature probe tip, was recorded. For each sequence, a calibration constant could be determined to be -0.0088 ± 0.0002 ppm °C(-1) (EPI), -1.15 ± 0.03 °C(-1) (FLASH), -1.49 ± 0.03 °C(-1) (IRTF), -1.21 ± 0.03 °C(-1) (SRTF), and -2.52 ± 0.12 °C(-1) (TRUFI). These constants were evaluated in further LITT experiments in phantom comparing the calculated temperatures with the fiber optic-measured ones; temperature precisions of 0.60 °C (EPI), 0.81 °C (FLASH), 1.85 °C (IRTF), 1.95 °C (SRTF), and 3.36 °C (TRUFI) were obtained. Furthermore, performing the Bland-Altman analysis, temperature accuracy was determined to be 0.23 °C (EPI), 0.31 °C (FLASH), 1.66 °C (IRTF), 1.19 °C (SRTF), and 3.20 °C (TRUFI). In conclusion, the seg-EPI sequence was found to be more convenient for MR temperature imaging of LITT due to its relatively high precision and accuracy. Among the T 1 method sequences, FLASH showed the highest accuracy and robustness.

Magnetic resonance temperature imaging of laser-induced thermotherapy: assessment of fast sequences in ex vivo porcine liver.

AIM: To evaluate magnetic resonance sequences for T(1) and proton resonance frequency (PRF) thermometry during laser-induced thermotherapy (LITT) in liver tissue. MATERIALS & METHODS: During LITT (1064 nm; 30 W; 3-cm diffuser; 2-3 min) in ex vivo porcine liver, temperature was measured (25-70°C) utilizing a fiberoptic thermometer and MRI was performed with a 1.5-T scanner through the following sequences: segmented echo planar imaging (seg-EPI) for the PRF method; fast low-angle shot (FLASH), inversion-recovery turbo FLASH (IRTF), saturation-recovery turbo FLASH (SRTF) and true-fast imaging (TRUFI) for the T(1) method. Phase angle and signal amplitude (regarding PRF/T(1)) was recorded in regions of interest, on images under fiberoptic probe tips. Sequences' thermal coefficients were determined by calibrating phase angle and signal amplitude against temperature and subsequently validated. RESULTS: Coefficients of -0.0089 ± 0.0003 ppm °C(-1) (seg-EPI) and -0.917 ± 0.046, -1.166 ± 0.058, -1.038 ± 0.054 and -1.443 ± 0.118°C(-1) (FLASH, IRTF, SRTF and TRUFI, respectively) were obtained. Precisions of 0.71, 1.34, 2.07, 2.44 and 3.21°C and, through Bland-Altman analysis, accuracies of -0.67, 0.79, 1.65, 1.57 and 2.13°C (seg-EPI, FLASH, IRTF, SRTF and TRUFI, respectively) were determined. CONCLUSION: The PRF method with seg-EPI sequence is preferred for thermometry during LITT owing to higher precision and accuracy. Among T(1)-method sequences, FLASH showed higher accuracy and robustness.

Effect of contrast material on radiation dose in an adult cardiac dual-energy CT using retrospective ECG-gating.

The purpose of this study was to determine the effect of contrast material and retrospective ECG-gating on radiation dose in an adult cardiac dual-energy computed tomography (DECT). Sixty-two patients underwent CT cardiac examination with a Somatom Definition Flash DECT using tube voltages of 100 kV without filter and 140 kV with a tin filter (mean effective mA s: arterial 72.39 and 62.94, venous 93.21 and 78.45, and late phase 134.5 and 118.2). The arterial and late phases were examined with retrospective ECG-gating, but gating was not used for the venous phase. Seventy milliliters (70 ml) iodinated contrast material (CM) was injected into the patient during examination. The effective doses (ED) were calculated from dose-length-product (DLP) and computed tomographic dose index volume (CTDIvol) using the latest k-factor (0.028). Pearson's correlation coefficient was used for statistical tests on continuous variables. Mean CTDIvol and DLP were lower in the late phase (10.15 ± 1.5 mGy and 202.9 ± 23 mGy cm) compared to the arterial phase (19.69 ± 3 mGy and 394 ± 90 mGy cm). Differences between the arterial and late phase were statistically significant (p = 0.005), and mean values for the late phase were 48.5% lower than mean values for the arterial phase. Mean CTDIvol and DLP were lower in venous (7.72 ± 1 mGy and 154.3 ± 17 mGy cm) compared to late phase (10.15 ± 1.5 mGy and 202.9 ± 23 mGy cm). The difference between venous and late phase was statistically significant (p < 0.001). The mean results for the venous phase were 24% lower than those for the late phase. This study shows that contrast material (CM) absorbs radiation significantly and increases dose by 48.5% in an adult cardiac dual-energy CT with retrospective ECG-gating. Care must be taken to determine the type, concentration, and volume of CM used for the scan. The dual-energy non-ECG-gated technique decreased radiation dose by 24% compared to the ECG-gated technique. ECG-gated cardiac examination should be limited to patients with strong clinical indications. SNR and HU increased with decreasing energy. The image noise values showed a negligible difference in the arterial and late phase datasets, and this did not affect the diagnostic quality of the image evaluation.

Repetitive chemoembolization of hypovascular liver metastases from the most common primary sites.

AIM: To evaluate tumor response in patients with hypovascular liver metastases from the most common primary sites treated with chemoembolization. MATERIALS & METHODS: Chemoembolization was performed in 190 patients (five groups) who had hypovascular liver metastases from the colon (n = 66), breast (n = 40), uveal malignant melanoma (n = 20), pancreas (n = 48) and stomach (n = 16). Surgical resection of primary sites had been performed for all included patients. Tumor response, survival statistics from the first chemoembolization using Kaplan-Meier method and progression rate of embolized lesions were evaluated by analysis of variance with Tukey's post hoc test. RESULTS: Multiple comparison between the groups showed no statistical significant difference in local tumor response (H: 9.23; p > 0.05). Survival indices of the patients, including survival rate, progression-free survival rate, median survival time and time to progression, demonstrated significant difference between the groups during the follow-up period (H: 9.7; p = 0.045). The progression rate of treated liver metastases from colon, breast, uvea, pancreas and stomach were 16.6, 17.5, 30.0, 25.0 and 32.0%, respectively (p = 0.002). CONCLUSION: Hypovascular liver metastases treated with chemoembolization may demonstrate equal local response, but are significantly different in rate of progression and survival.

Thermal ablation therapies in patients with breast cancer liver metastases: a review.

BACKGROUND: The liver is involved in about half of patients with metastatic breast cancer. Unfortunately systemic chemotherapy as the treatment of choice is limited. Due to multifocality and/or insufficient remnant liver volume, the majority of liver metastases are also unresectable. Currently, thermal ablations are used in these patients with acceptable impact. METHODS: We reviewed studies on radiofrequency ablation (RFA), laser-induced thermotherapy (LITT) and microwave ablation (MWA) regarding local tumour response, progression and survival indexes in patients with breast cancer liver metastases (BCLM). RESULTS: The reviewed literature showed positive response rates of 63 % to 97 % in RF-ablated lesions, 98.2 % in LITT-treated lesions and 34.5-62.5 % in MW-ablated lesions. Median survival was 10.9-60 months using RFA, 51-54 months after LITT and 41.8 months using MWA. Five-year survival rates were 27-30 %, 35 % and 29 %, respectively. Local tumour progression ranged from 13.5 % to 58 % using RFA, 2.9 % with LITT and 9.6 % with MWA. CONCLUSION: The reviewed literature demonstrated that ablation therapies either as single therapy or combined with other locoregional therapies are a good alternative as an adjunction to resection in patients with resectable lesions or with positive response using chemotherapy. However, multicentre randomised studies should be conducted to obtain further evidence of the benefits of these treatments in patients with BCLM.

Retrospective study on the use of different protocols for repeated transarterial chemoembolization in the treatment of patients with hepatocellular carcinoma.

PURPOSE: To evaluate local tumor control and survival rate after repeated transarterial chemoembolization using two different protocols in hepatocellular carcinoma (HCC) patients. MATERIALS AND METHODS: A total of 190 patients (mean, 68 years) with HCC were repeatedly treated with transarterial chemoembolization in 4-week intervals. The chemotherapy protocol consisted of mitomycin C alone (n = 111) and mitomycin C with gemcitabine (n = 79). Embolization was performed with lipiodol and microspheres. Tumor response was evaluated by magnetic resonance imaging using Response Evaluation Criteria In Solid Tumors (RECIST) criteria. Survival rates were calculated using Kaplan-Meier method. RESULTS: In the mitomycin C-only group, we observed partial response in 38.8% (43/111), stable disease in 27% (30/111), and progressive disease in 34.2% (38/111). In the mitomycin C/gemcitabine group (n = 79), partial response was observed in 43% (34/79), stable disease in 16.5% (13/79) and progressive disease in 40.5% (32/79). The overall 1- and 2-year survival rates were 56% and 28%, respectively. The overall median survival time from the start of transarterial chemoembolization treatment was 15 months. The median survival of patients treated with mitomycin C was 16.5 months and it was 12 months for patients treated with a combination of mitomycin C and gemcitabine. No statistically significant difference between the two groups was observed (P = .7). CONCLUSION: Chemoembolization is an effective minimally invasive therapy option for palliative treatment of HCC patients. Mitomycin C only proves to be effective, the addition of gemcitabine was not advantageous.

Liver metastases of pancreatic cancer: role of repetitive transarterial chemoembolization (TACE) on tumor response and survival.

OBJECTIVE: To evaluate the effect of chemoembolization on pancreatic cancer liver metastases. METHOD: Thirty-two patients with pancreatic cancer liver metastases retrospectively underwent chemoembolization (4- to 8-week intervals). Size-based evaluation (response evaluation criteria in solid tumors [RECIST]) and survival indexes were assessed overall and for sex and number of lesions. RESULTS: Of the patients, 71.87% showed stable disease, 9.37% partial response (PR) and 18.75% progressive disease (PD). Survival rate for 1, 3, and 5 years from first TACE was 60%, 25%, and 11%, respectively. Median survival time was 16 months and for stable disease group was 20 months. Progression-free survival for 6 months and 1, 3, and 5 years was 84%, 57.3%, 20%, and 10%, respectively. There was significant difference between men and women in response. Survival rates for 1 and 5 years for the men were 80% and 14% and for the women were 47% and 0%. There was no significant difference between oligonodular liver lesion (n < 5) and multinodular (n > 5) groups. Survival rates for 1 and 5 years for oligonodular were 84% and 14%, and for multinodular was 50% and 0%. CONCLUSION: Repetitive TACE resulted in a relevant response for the control of liver metastases of pancreatic cancer with respectable median survival time. Interestingly, the number of lesions, statistically, was not an effective factor.

A liver-mimicking MRI phantom for thermal ablation experiments.

PURPOSE: To develop a liver-mimicking MRI gel phantom for use in the development of temperature mapping and coagulation progress visualization tools needed for the thermal tumor ablation methods, including laser-induced interstitial thermotherapy (LITT) and radiofrequency ablation (RFA). METHODS: A base solution with an acrylamide concentration of 30 vol. % was prepared. Different components were added to the solution; among them are bovine hemoglobin and MR signal-enhancing contrast agents (Magnevist as T1 and Lumirem as T2 contrast agent) for adjustment of the optical absorption and MR relaxation times, respectively. The absorption was measured in samples with various hemoglobin concentrations (0%-7.5%) at different temperatures (25-80 degrees C) using the near-infrared spectroscopy, measuring the transmitted radiation through the sample. The relaxation times were measured in samples with various concentrations of T1 (0.025%-0.325%) and T2 (0.4%-1.6%) contrast agents at different temperatures (25-75 degrees C), through the MRI technique, acquiring images with specific sequences. The concentrations of the hemoglobin and contrast agents of the gel were adjusted so that its absorption coefficient and relaxation times are equivalent to those of liver. To this end, the absorption and relaxation times of the gel samples were compared to reference values, measured in an ex vivo porcine liver at different temperatures through the same methods used for the gel. For validation of the constructed phantom, the absorption and relaxation times were measured in samples containing the determined amounts of the hemoglobin and contrast agents and compared with the corresponding liver values. To qualitatively test the heat resistance of the phantom, it was heated with the LITT method up to approximately 120 degrees C and then was cut to find out if it has been melted. RESULTS: In contrast to liver, where the absorption change with temperature showed a sigmoidal form with a jump at T approximately equal 45 degrees C, the absorption of the gel varied slightly over the whole temperature range. However, the gel absorption presented a linear increase from approximately 1.8 to approximately 2.2 mm(-1) with the rising hemoglobin concentration. The gel relaxation times showed a linear decrease with the rising concentrations of the respective contrast agents. Conversely, with the rising temperature, both T1 and T2 increased linearly and showed almost the same trends as in liver. The concentrations of hemoglobin and T1 and T2 contrast agents were determined as 3.92 +/- 0.42 vol. %, 0.098 +/- 0.023 vol. %, and 2.980 +/- 0.067 vol. %, respectively. The measured ex vivo liver T1 value increased from approximately 300 to approximately 530 ms and T2 value from approximately 45 to approximately 52 ms over the temperature range. The phantom validation experiments resulted in absorption coefficients of 2.0-2.1 mm(-1) with variations of 1.5%-2.95% compared to liver below 50 degrees C, T1 of 246.6-597.2 ms and T2 of 40.8-67.1 ms over the temperature range of 25-75 degrees C. Using the Bland-Altman analysis, a difference mean of -6.1/1.9 ms was obtained for T1/T2 between the relaxation times of the phantom and liver. After heating the phantom with LITT, no evidence of melting was observed. CONCLUSIONS: The constructed phantom is heat-resistant and MR-compatible and can be used as an alternative to liver tissue in the MR-guided thermal ablation experiments with laser to develop clinical tools for real-time monitoring and controlling the thermal ablation progress in liver.