WE-G-217A-02: RF Heating of DBS Lead with T/R Head Coil versus T/R Body Coil

PURPOSE

To evaluate the difference in RF heating of deep brain stimulator (DBS) leads during MRI procedures using head-only transmitting coil versus whole-body transmitting coil.

METHODS

A DBS lead was inserted into the center of a 3-liter head phantom constructed and filled with gel prepared according the specifications in ATSM standard 2182. The portion of the lead outside of the head phantom was either coiled and fixed to phantom exterior (lead only), similar to that in DBS implanting surgery, or connected through an extension cable to an IPG, which is set to zero mA output and turned off (lead+Ext.+IPG). Imaging was performed on a 1.5T MRI scanner using either a T/R head coil or the built-in T/R body coil. Two different scans: 3D MPRAGE (low SAR) and 3D TSE (high SAR) were performed. The temperature at the tip of the DBS lead was recorded every 10s using a fiber optical probe.

RESULTS

For lead only, the maximum temperature change (peak-to-peak) was less than 0.1 C with all scans or coils. For lead+Ext.+IPG, 0.4 C change was observed with T/R head coil and 0.95 C with T/R body coil for 3D MPRAGE (low SAR). However, 18.0 C and 35.3 C changes were observed, respectively, for 3D TSE (high SAR).

CONCLUSIONS

If the DBS lead is NOT connected to the IPG, no substantial difference in RF heating between the use of a T/R head coil and body coil transmit was observed. The temperature changes were minimal even under high SAR. Such results suggests that DBS MRI may be performed safely with transmitting through body coil and receiving through phased array surface coils provided ONLY the lead is present which is often the case during intra-operative procedures. Since further study is needed, extreme caution is advised before extrapolating these results to patient exams.

Development of a geometrically accurate imaging protocol at 3 Tesla MRI for stereotactic radiosurgery treatment planning

The purpose of this study is to develop a geometrically accurate imaging protocol at 3 T magnetic resonance imaging (MRI) for stereotactic radiosurgery (SRS) treatment planning. In order to achieve this purpose, a methodology is developed to investigate the geometric accuracy and stability of 3 T MRI for SRS in phantom and patient evaluations. Forty patients were enrolled on a prospective clinical trial. After frame placement prior to SRS, each patient underwent 3 T MRI after 1.5 T MRI and CT. MR imaging protocols included a T1-weighted gradient echo sequence and a T2-weighted spin echo sequence. Phantom imaging was performed on 3 T prior to patient imaging using the same set-up and imaging protocols. Geometric accuracy in patients and phantoms yielded comparable results for external fiducial reference deviations and internal landmarks between 3 T and 1.5 T MRI (mean ≤ 0.6 mm; standard deviation ≤ 0.3 mm). Mean stereotactic reference deviations between phantoms and patients correlated well (T1: R = 0.79; T2: R = 0.84). Statistical process control analysis on phantom QA data demonstrated the stability of our SRS imaging protocols, where the geometric accuracy of the 3 T SRS imaging protocol is operating within the appropriate tolerance. Our data provide evidence supporting the spatial validity of 3 T MRI for targeting SRS under imaging conditions investigated. We have developed a systematic approach to achieve confidence on the geometric integrity of a given imaging system/technique for clinical integration in SRS application.

International collaboration is feasible in trials for rare conditions: the EURAMOS experience

The introduction of multi-agent chemotherapy dramatically improved the outcome for patients with osteosarcoma. However, we appear to have reached a plateau in outcome with a long-term event-free survival of 60-70%. Therefore, detection of further improvements will likely require larger numbers of patients. This goal is best achieved via randomized clinical trials (RCTs) requiring large-scale cooperation and collaboration. With this background, four multinational groups agreed on the merits of collaboration: Children's Oncology Group (COG), Cooperative Osteosarcoma Study Group (COSS), European Osteosarcoma Intergroup (EOI) and Scandinavian Sarcoma Group (SSG); they designed a study to determine whether altering postoperative therapy based on histological response improved the outcome. The study design includes a backbone of 10 weeks of preoperative therapy using MAP (methotrexate, Adriamycin and cisplatin). Following surgery, patients are stratified according to histological response. Patients classified as "good responders" (>or=90% necrosis) are randomized to continue MAP or to receive MAP followed by maintenance pegylated interferon, while "poor responders" (<90% necrosis) are randomized to either continue MAP or to receive MAPIE (MAP+ifosfamide, etoposide). The design includes the registration of 1,400 patients over 4 years as well as the evaluation of quality of life using two different instruments. The group has established an efficient infrastructure to ensure successful implementation of the trial. This has included the EURAMOS Intergroup Safety Desk, which has established an international system for SAE, SAR and SUSAR reporting to the relevant competent authorities and ethics committees for each participating country. The group has also developed trial site monitoring and data center audits with funding from the European Science Foundation (ESF). The ESF has also funded three training courses to familiarize institutional staff with the requirements of multinational GCP trials. We have established a successful collaboration, and as of February 2008, 901 patients have been enrolled (COG 448; COSS 226; EOI 181; SSG 46) from 249 institutions in 16 different countries. As expected, 80% of the patients are <18 years of age, and accrual into the Quality of Life sub-study is proceeding as planned with 90% of the subjects agreeing to participate. International awareness is increasing and procedures for applicant countries wishing to join the collaboration have been implemented. Details about EURAMOS can be found at www.euramos.org. International trials in rare diseases are practicable with appropriate funding, planning and support. Although the implementation of such trials is difficult and time consuming, it is a worthwhile effort to rapidly complete RCTs and identify interventions that will improve the outcome of all osteosarcoma patients.EURAMOS-1 is the fastest accruing osteosarcoma trial and is already the largest osteosarcoma study conducted.

Day-case neurosurgery for brain tumours: the early United Kingdom experience

Day-case biopsy and craniotomy for brain tumours have been reported as safe and feasible options for selected patients. The incidence and timing of complications after such procedures has also been characterized in recent publications. However, more widespread adoption of day-case cranial neurosurgery has not taken place. We report the first UK series of day-case surgery for intra-axial tumours, consisting of 30 image-guided biopsies and 11 craniotomies, taking place over 1 year from October 2006. Patients were studied prospectively and 27/30 biopsy and 9/11 craniotomy patients were discharged 6 h postoperatively. One biopsy case was admitted due to increased headache postoperatively, but with a normal CT and one craniotomy case had transient worsening of lower limb paresis requiring overnight admission. The three other overnight admissions were for patient preference. One biopsy patient was readmitted 30 h postoperatively with a seizure and discharged the following day. No patients suffered an adverse outcome. The results are presented together with the Toronto series of 284 cases over 11 years, also with no patients suffering an adverse outcome because of planned early discharge. These results suggest that day-case surgery for brain tumours is a safe and feasible option for patients in the UK.

Cure following gene therapy for recurrent glioblastoma multiforme?

We report a patient with glioblastoma multiforme who is alive and disease-free 13 years following aggressive treatment with multiple surgeries, radiotherapy, chemotherapy, and gene therapy.

Prognostic factors for patients with Ewing sarcoma (EWS) at first recurrence

10011

Background: The prognosis for patients with recurrent Ewing sarcoma (EWS) is very poor with 5-year survival of 13%. Since 30–40% of patients with newly diagnosed, non-metastatic EWS develop recurrence, the Children's Oncology Group (COG) sought to evaluate prognostic factors for these patients. Data was derived from the phase III, multi-institutional study INT 0091. Methods: Between 1988 and 1994, five hundred and seventy-eight eligible patients with previously untreated EWS or PNET of bone were enrolled on INT 0091. Patients who experienced recurrence or disease progression as their first analytic event were considered. Survival was calculated from date of disease progression to death or last patient contact. Comparisons of the risk for death across groups were accomplished using the log-rank test. Survivor functions were estimated by the method of Kaplan and Meier. Results: Two hundred and sixty-two patients experienced disease progression or recurrence. The median time to first recurrence was 1.3 years (range 0–7.4 years) for all patients, 1.4 years (range 0 to 7.4 years) for patients with initially localized disease and 1 year (range 0 to 6 years) for patients with initially metastatic disease. Time to first recurrence from date of initial diagnosis was a predictor of post-recurrence survival (p<0.0001). Twenty-one percent of patients whose disease recurred or progressed experienced first recurrence 2 or more years from initial diagnosis and had an estimated 5 year post-recurrence survival of 30%. This compares with 7% for those whose first recurrence or progression was earlier. No statistical difference was detected when patients whose disease recurred < 12 months were compared with those whose recurrence was 12–24 months from initial diagnosis. Significant risk factors for death after recurrence included metastatic disease at initial diagnosis, elevated LDH at initial diagnosis and female gender. In patients non-metastatic at initial diagnosis pelvic primary site was also a risk factor for death after recurrence. Conclusions: Patients with longer time to first recurrence represent the subset of patients most likely to survive following recurrence. All patients with recurrent Ewing sarcoma would benefit from collaborative trials to investigate new therapeutic options.

No significant financial relationships to disclose.

First toxicity and efficacy analysis of a phase II trial of a novel 5-FU-oxaliplatin based chemoradiation schema for stage II and III rectal carcinoma

14591

Background: 5-FU based neoadjuvant chemoradiation (CRT) has become the standard of care for stage 2 and 3 rectal cancer (ca). Pathologic complete responses (pCR) and downstaging have been associated with improved survival outcomes. The addition of oxaliplatin or irinotecan to neoadjuvant treatment has led to improved pCR and downstaging. The feasibility and efficacy of “total” oxaliplatin therapy (pre and postoperative oxaliplatin) for stage 2 and 3 rectal ca patients has yet to be defined. Objective: To determine the feasibility, toxicity and efficacy of neoadjuvant oxaliplatin, 5-FU and RT followed by surgery, with postop adjuvant modified FOLFOX6. Methods: Single institution, single arm phase II trial of oxaliplatin 60mg/m2 weekly for 6 weeks with continuous infusion 5- FU 225 mg/m2/excision. Postoperative therapy consisted of mFOLFOX6 every 2 weeks for 6 cycles. Eligibility included previously untreated, histologically proven rectal cancer, T3–4N0M0 or TanyN+M0 (stage II-III). Results: 15 pts have been enrolled in this study. One died of disease prior to CRT. Eight pts have completed total oxaliplatin therapy. One pt had 1 cycle deleted due to grade 2 neuropathy. Prior to adjuvant therapy 2 pts dropped out: 1 from pulmonary symptoms and one asthenia. Two pts attained a pCR and 6 attained downstaging. Significant toxicity has been limited to grade 3 neuropathy in one pt (completely resolved) and one grade 3 GI toxicity (self limited). Conclusions: Early analysis shows the feasibility of pre and post operative oxaliplatin based therapy. The limited data permit only observation of pCR and tumor downstaging rates but toxicity outcomes are encouraging. Further accrual and follow-up will better define efficacy and toxicity of this regimen.

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International collaboration is feasible in trials for rare conditions: The EURAMOS experience

20501

Background: Osteosarcoma is rare and the outcome for patients has plateaued following the introduction of multi-agent chemotherapy. To demonstrate further improvements would likely require large numbers of patients, only achievable in this setting via International collaboration. Therefore, in October 2001, 4 multinational groups - Children's Oncology Group (COG), Cooperative Osteosarcoma Study Group (COSS), European Osteosarcoma Intergroup (EOI) and Scandinavian Sarcoma Group (SSG) - agreed on the merits of collaboration to determine whether altering post-operative therapy based on histological response improved outcome. Following a number of practical and regulatory hurdles the trial opened to accrual in April 2005. Methods: Eligibility criteria include: new diagnosis with resectable osteosarcoma; age <40 years; normal organ function. Standard therapy includes 29 weeks of cisplatin, doxorubicin and high-dose methotrexate (MAP). Following two cycles of cisplatin/doxorubicin and 2–6 cycles of high-dose methotrexate, patients undergo resection. Post-operative therapy is dependent on histological response. Good histological responders (>90% necrosis) are randomized to continuing MAP or MAP with maintenance pegylated interferon. Poor histological responders are randomized to MAP or MAP plus ifosfamide and etoposide. Results: All groups are recruiting and accrual is ahead of schedule: 373 patients have been enrolled (159 COG, 108 COSS, 83 EOI, 23 SSG) and 160 patients randomized: 87 (54%) good responders (46 MAP), 73 (46%) poor responders (39 MAP). Conclusions: International collaboration is feasible and results in rapid accrual of large number of patients. The implementation of such trials is difficult and time consuming due to the complexity of multinational regulatory issues. However, the effort is worthwhile to potentially improve outcomes for patients with rare diseases.

No significant financial relationships to disclose.

A method for quantification of nucleotides and nucleotide analogues in thymidine kinase assays using lanthanum phosphate coprecipitation

Current methodologies for quantifying radiolabeled nucleoside monophosphates and nucleoside analogues result in high retention of unphosphorylated guanosine nucleosides in the case of lanthanum chloride precipitation or inconsistent retention of nucleotides in the case of DEAE cellulose filter papers. This study describes an innovative method for quantifying thymidine kinase (TK) activity that is compatible with both purine and pyrimidine nucleoside analogues by using lanthanum phosphate coprecipitation at pH 4.0. This methodology maintains quantitative precipitation of nucleoside monophosphates and yields minimal background binding from a variety of nucleoside analogues. In addition, use of PCR thermocyclers enhances the temporal precision of TK assays. This method was shown to be useful for assaying TK activity in a broad range of biochemically relevant systems, including purified enzymes, stable cell lines, and virally infected cells. Use of this methodology should aid researchers in the evaluation of novel nucleoside analogues and TK enzymes while decreasing radioactive waste, minimizing assay time, increasing accuracy, and enhancing dynamic range.