PVA particles are associated with intense uterine necrosis and extensive arterial occlusion regardless of size. Calibrated MS, which are associated with less uterine necrosis, permit a segmental arterial occlusion correlated with size.

MRI can be used for monitoring temperature during a thermocoagulation treatment of tumors. The aim of this study was to demonstrate the suitability of a 3D steady-state free precession sequence (3D Fast Imaging with Steady-State Precession, 3D TrueFISP) for MR temperature measurement at 0.23 T, and to compare it to the spin-echo (SE) and spoiled 3D gradient-echo (3D GRE) sequences. The optimal flip angle for the TrueFISP sequence was calculated for the best temperature sensitivity in the image signal from liver tissue, and verified from the images acquired during the thermocoagulation of excised pig liver. The treatment of hepatic metastases by local heat delivery has drawn considerable interest over the last few years. The efficiency of thermoablation is improved if real-time monitoring of heat distribution is available during the treatment (1-3). At the moment, MRI is the only medical imaging modality that can provide noninvasive temperature information from tissue.Temperature monitoring with MRI is possible using the temperature sensitivity of the proton resonance frequency, i.e., chemical shift (4), diffusion (5), or longitudinal relaxation time T 1 and equilibrium magnetization M 0 (6 -8). The applicability of each method depends on the field strength of the MR scanner used, and on the target anatomy (9).Low-field open magnets are well suited for performing tumor ablations. They offer maximum access to the patient; dedicated tools for interventional MRI, such as needle tracking systems and in-room controls; less-intense needle artifacts; and lower-cost procedures. A disadvantage is that temperature-measuring methods utilizing the temperature sensitivity of the proton resonance frequency are difficult to use, as the change in chemical shift is directly proportional to field strength. For example, the sensitivity is 6.5 times less sensitive at 0.23 T than at 1.5 T.Motion artifacts hamper diffusion-based temperature measurement methods (10), making them impractical for use in the liver. With low-field open scanners, the easiest method for obtaining temperature data from the liver is to use the temperature dependence of T 1 and M 0 . Their temperature sensitivity is still high at lower magnetic field strengths, and they are easily measurable with standard sequences and hardware.The accuracy of temperature measurement with T 1 and M 0 depends strongly on the type of MR sequence used and on the choice of acquisition parameters, such as the repetition time (TR) and flip angle (␣). Temperature resolution may be affected by a factor of 5, depending on the type of sequence used for the measurement (11). The parameters need to be carefully chosen to optimize the temperature measurement while maintaining a reasonable temporal and spatial resolution.Spin-echo (SE) sequences, gradient-recalled acquisitions in the steady state (GRASS), and spoiled gradientrecalled acquisitions (SPGR) have been employed for monitoring temperature by using the temperature dependency of T 1 (7,8,11,12). A steady-state sequence (3D Fast Imagi...

Thermal therapy of tumour including hyperthermia and thermal ablation by heat or cold delivery requires on line monitoring. Due to its temperature sensitivity, Magnetic Resonance Imaging (MRI) allows thermal mapping at the time of the treatment. The different techniques of MR temperature monitoring based on water proton resonance frequency (PRF), longitudinal relaxation time T1, diffusion coefficient and MR Spectroscopic Imaging (MRSI) are reviewed and debated. The PRF method appears the most widely used and the most efficient at high magnetic field in spite of important drawbacks. The T1 method is the easiest method of visualisation of qualitative temperature distribution and quantitative measurement seems possible in the tissue surrounding the tumour up to a temperature of 45-65 degrees C. Despite its high temperature sensitivity, application of the diffusion method in vivo is restricted due to its high motion sensitivity. The recent MRSI technique seems very promising provided acquisition times can be reduced. Results from the literature indicate that MR temperature monitoring in vivo can be achieved in vivo with a precision of about 3 degrees C in 13 s for a voxel of 16 mm3 (1.5 x 1.5 x 7 mm) in 1.5 T scanners.

The aims of this study were, firstly, to monitor temperature with magnetic resonance (MR) during laser ablations performed in pig livers in vivo in a low‐field open scanner (0.23T) and, secondly, to study the feasibility of lesion size prediction. Spin‐echo (SE) images of 29 sec acquired during laser applications allowed calculation of temperature maps using T1 and M0 temperature sensitivity. Temperature was also measured with thermocouples. Images of prediction of tissue damage were calculated using temperature maps and Arrhenius model. T2W sequences were acquired after the ablations. Animals were sacrificed immediately. Lesions were photographed macroscopically. Lesion surfaces were measured and compared in T2W images, temperature images, damage prediction images, and macroscopic pictures. A correlation exists between temperature measured with MR and with thermocouples (ρ = 0.878; P < 0.001, Spearman test). Mean surface of predicted damaged tissue is consistent with mean early necrosis measured in macroscopic pictures. Early T2W images underestimate mean necrosis size. J. Magn. Reson. Imaging 2001;13:42–49. © 2001 Wiley‐Liss, Inc.

406 Introduction: In 2000, the Gela demonstrated the survival advantage of adding Rituximab to CHOP21 over CHOP21 in the treatment of diffuse large B-cell lymphoma (DLBCL) in elderly patients. Two consecutive studies from the German group have shown an improvement of survival with CHOP14 compared to CHOP21, and then after with R-CHOP14 compared to CHOP14. Here, we report the results of the planned interim analysis of the LNH03-6B, a multicentric, phase III open-label, randomized trial evaluating the efficacy of R-CHOP given every 14 days compared to R-CHOP given every 21 days, held after the inclusion of the first 202 patients, with a median follow-up of 24 months. Patients and methods: Patients between 60 and 80 years old with DLBCL and aaIPI ≥ 1 were eligible. They were randomized between two immunochemotherapy regimens combining Rituximab and CHOP given every 2 (R-CHOP14, arm A) or 3 weeks (R-CHOP21, arm B) for 8 cycles. They were subsequently randomized between a prophylactic treatment with Darbepoetin alfa and a conventional treatment of chemotherapy-induced anemia. G-CSF was given according to physician decision. The primary objective was to evaluate the efficacy of R-CHOP14 compared to R-CHOP 21 as measured by the EFS, events being defined as death from any cause, relapse for complete responders and unconfirmed complete responders, progression during or after treatment and changes of therapy during allocated treatment. Secondary objectives were OS, PFS, DFS, response rate and analysis of dose-intensity and toxicity. According to previous LNH98-5 protocol, sample size was calculated to demonstrate an improvement of 2-year EFS from 55% to 65% with R-CHOP14. Six-hundred patients, randomized 1:1 between the two treatment groups recruited over 4 years and followed for a minimum of one year, will provide 80% power at the overall 5% (2-sided) significance level to detect the expected difference. Results: In this planned interim analysis, 202 patients were randomized and 201 received study treatment, 103 with R-CHOP14 and 98 with R-CHOP21. Median age was 72 years. Patients' characteristics were similar in both groups with a slightly higher proportion of patients with aaIPI 2-3 in R-CHOP14 arm (67% vs 59%) whereas a higher proportion of patients in R-CHOP21 arm presented with B symptoms (43% vs 37%). The median interval between cycles was 15 days in R-CHOP14 group and 21 days in R-CHOP21 group; 73 patients (71%) in R-CHOP14 group and 74 patients (76%) in R-CHOP21 group completed 8 cycles without progression. In the R-CHOP14 group, the increase of dose-intensity at the end of treatment, calculated according to 3-week interval as a reference, was 125% for cyclophosphamide and doxorubicin. Ninety percent of patients treated with R-CHOP14 received G-CSF, whereas only 66% in R-CHOP21 group. Response rate (CR+CRu) was 67% in R-CHOP14 arm and 75% in R-CHOP21 arm (p=NS). The 2-year EFS was 48% in R-CHOP14 arm compared with 61% in R-CHOP21 (p=NS). A similar trend was observed for 2-year PFS (49% vs 63%), 2-year DFS (57% vs 70%) and 2-year OS (67% vs 70%) (p=NS for all). Grade 3-4 hematological toxicity was more frequent in R-CHOP14 group, with a higher proportion of patients receiving red cell or platelet transfusions and/or experiencing febrile neutropenia, resulting in higher proportion of patients hospitalized for adverse events. In contrast, there was no difference for extra-hematological grade 3-4 toxicities. Conclusions: The results of this interim analysis of the LNH03-6B trial favor treatment with R-CHOP21 in elderly patients with DLBCL, with trends toward higher efficacy and lower toxicity compared to R-CHOP14. These results should be confirmed by the final analysis, concerning the 602 patients included, planned in 2010. Disclosures: No relevant conflicts of interest to declare.