No abstract

Purpose:To assess the reproducibility of intrinsic relaxivity and both relaxivity-and susceptibility-based dynamic contrast enhanced (DCE) MRI in pelvic tumors; to correlate kinetic parameters obtained and to assess whether acute antivascular effects are seen in response to cisplatin-or taxane-based chemotherapy. Materials and Methods:T 1 -weighted and T 2 *-weighted DCE-MRI and basal R 2 * measurements were performed on three consecutive days in women with gynecological tumors. The third scan was 21.0 (range 17.3-23.5) hours after the first cycle of chemotherapy. Kinetic parameter estimates were obtained and correlated between techniques. Test-retest reproducibility and response to treatment were assessed. Results:Relative blood volume (rBV) and relative blood flow (rBF) correlated strongly with transfer constant (K trans ), k ep , and the initial area under the gadopentetate dimeglumine (Gd-DTPA) concentration-time curve (IAUGC) (all P Ͻ 0.01). The group 95% confidence interval (CI) for change was -10.8 to ϩ12.1%; Ϯ5.1%; -9.5 to ϩ10.5%; Ϯ7.5%; for K trans , v e , k ep , and IAUGC, respectively, and Ϯ13.6%, Ϯ2.4%, Ϯ11.6%, and Ϯ11.0%, for rBV, mean transit time (MTT), rBF, and R 2 *, respectively. There were no significant acute changes in kinetic parameter estimates in response to treatment on group analysis, apart from a small decrease in v e . Conclusion:The results confirm the dominant influence of flow on K trans in untreated gynecological tumors. There is no evidence of an acute, large magnitude antivascular effect caused by cisplatin-or taxane-based chemotherapy.

Dynamic contrast enhanced MRI (DCE-MRI) is being used increasingly in clinical trials to demonstrate that vascular disruptive and antiangiogenic agents target tumour microcirculation. Significant reductions in DCE-MRI kinetic parameters are seen within 4 -24 and 48 h of treatment with vascular disruptive and antiangiogenic agents, respectively. It is important to know whether cytotoxic agents also cause significant acute reductions in these parameters, for reliable interpretation of results. This study investigated changes in transfer constant (K trans ) and the initial area under the gadolinium curve (IAUGC) following the first dose of chemotherapy in patients with mostly gynaecological tumours. A reproducibility analysis on 20 patients (using two scans performed on consecutive days) was used to determine the significance of DCE-MRI parameter changes 24 h after chemotherapy in 18 patients. In 11 patients who received platinum alone or with a taxane, there were no significant changes in K trans or IAUGC in either group or individual patient analyses. When the remaining seven patients (treated with a variety of agents including platinum and taxanes) were included (n ¼ 18), there were also no significant changes in K trans . Therefore, if combination therapy does show changes in DCE-MRI parameters then the effects can be attributed to antivascular therapy rather than chemotherapy.

No abstract

No abstract