Search

Purpose:  To compare local tumor control after percutaneous tumor ablation by interstitial laser therapy (ILT) or CT-guided brachytherapy (CTGB). Patients and Methods:  In a matched pair analysis including 18 patients with 36 liver metastases of colorectal primary, both ILT and CTGB were performed in different lesions. The following matching factors were considered: (i) tumor size ≤ 5 cm, and (ii) execution of chemotherapy after tumor ablation. Primary endpoint was local tumor control. Results:  Treated lesions were identical in terms of tumor size and all matching criteria were fulfilled in all patients except for the performance of adjuvant chemotherapy. Median follow-up was 14 months (3–24 months) for both groups. Only five of 18 patients (28%) demonstrated local tumor progression after CTGB, whereas in ten of 18 patients (56%) tumor progression was found after ILT. Differences encountered were significant for all patients (p = 0.04), whereas in those who fulfilled all matching criteria (n = 14) the level of statistical significance was not reached (p = 0.23). Conclusion:  CTGB demonstrated superior local tumor control compared to ILT in long-term follow-up. [ABSTRACT FROM AUTHOR]

Purpose:  To assess differences in delineated target volumes of liver metastases using contrast-enhanced CT and different MRI sequences for radiation treatment planning. Patients and Methods:  25 patients with 43 colorectal liver metastases were recruited. Tumor margins were defined by two experienced radiologists. The resulting D90 was assessed and the CT-based 3-D dose distribution merged with the according MRI dataset by employing image fusion. A theoretical D90 as a result of MRI-based treatment planning was assessed for various MRI sequences individually. Results:  In venous phase contrast-enhanced CT, the mean tumor volume was 20 ml; T1-weighted (T1w) MRI, 27 ml; contrast-enhanced T1w 42 ml; T2w 65 ml. The difference between the target volumes as assessed by either CT or MRI was 181% for T1w images, 178% for contrast-enhanced T1w, and 246% for T2w sequences. All differences were statistically significant (p The analysis of the dose-volume histograms revealed statistically significant differences (i.e., for the D90) for the different target volumes specified by CT and MRI: mean D90 on CT, 18 Gy; plain T1w, 16 Gy; contrast-enhanced T1w, 15.5 Gy; T2w, 12 Gy. Hence, delineation of a larger target volume in T2w MRI compared to contrast-enhanced CT resulted in a smaller D90. The mean differences of tumor volumes assessed by CT and plain T1w were significantly higher in the group of patients showing local tumor recurrences as compared to patients with long-term local tumor control (p = 0.002). Conclusion:  For treatment planning of liver metastases, the use of either plain T1w or T2w sequences is recommended to delineate the clinical target volume as completely as possible and not to miss potential tumor cell congregations in the surroundings as in CT. [ABSTRACT FROM AUTHOR]