A Novel Approach of Combined High Resolution T2-w and Parametrically Analyzed Dynamic Contrast Enhanced T1-w MR Imaging for Radiation Treatment Planning of the Prostate

Ziele: To evaluate image fusion of high resolution T2-weighted (T2-w) and parametrically analyzed dynamic contrast enhanced T1-weighted (T1-w) MR images (T1-w DCE MRI) with the planning CT scan within treatment planning systems for radiation therapy of the prostate. Methode: MRI of the prostate was performed on a 1.5 T unit with a phased-array body coil prior to treatment in patients with histologically proven prostate cancer. T2-weighted fast spin-echo images (TR 3220ms, TE 114ms, flip angle 180 deg, FOV 140mm, matrix size 256×256, slice thickness 3mm) and dynamic Gd-DTPA enhanced 3D-FLASH images were acquired (TR 8ms, TE 4.6ms, flip angle

18 deg, FOV 140mm, matrix size 128×128, slice thickness 3mm, one precontrast, 10 postcontrast measurements, no time interval between postcontrast measurements). The dynamic T1-weighted contrast enhanced images were analyzed pixel by pixel with a pharmocokinetic model. These colored parametric maps were superimposed on the T2 images to identify and localize the regions of tumor using a workstation of CAD-Sciences. Ergebnis: It was impossible for Eclipse (Varian), Coherence (Siemens) und Masterplan (Nucletron) to import the colored fused images into the radiation treatment planning system. However Eclipse and Coherence were able to import the non-colored parametric maps seperately with the T2-weighted images, followed by image fusion within the treatment planning system.Coherence shows in the 3D menu an incorrect representation of the T1-w DCE data in the fused images, however a correct representation in the Vsim menu for target delineation. Multimodality image fusion with CT was done successfully within 10 to 15 minutes followed by target delineation. Only Eclipse allows target delineation in the MR and/or CT images. Masterplan does not allow a fusion of different MR sequences resulting in a difficult verification of image fusion between CT and T1-w DCE data. Schlussfolgerung: Further diagnostic trials should determine the best DCE MRI sequence for optimal enhancement characteristics with regard to sensitivity and specificity in order to evaluate the functional/morphological tumor volume as close as possible to the margins of the histological tumor volume. Future clinical trials will show if this novel approach of combined high resolution T2 and parametrically analyzed DCE MR imaging might improve target delineation of prostate cancer for 3D conformal external-beam radiation therapy, IMRT or 3D conformal HDR brachytherapy (dose painting).

Korrespondierender Autor: Schmuecking M

KKH Greiz, Radiologisches Zentrum, Wichmannstr. 12, 07973 Greiz

E-Mail: [e-mail]

Prostate Cancer - CAD - Radiation Treatment Planning