Objective:

To study the effects of three-dimensional turbo spin echo (3D TSE) based and three-dimensional inversion-recovery gradient echo (3D IR-GRE) based T1-weighted enhanced magnetic resonance images on the definition of gross tumor volume (GTV).

Methods:

T1-weighted enhanced magnetic resonance images of 9 patients with brain metastases were acquired using 3D TSE and 3D IR-GRE r

espectively. A radiation oncologist with many years of experience in the treatment of brain metastasis contoured the GTVs on both sets of images. The volume difference between the two groups of GTVs were examined using the Wilcoxon signed rank sum test. The geometric agreement of the GTVs was evaluated by the Dice similarity coefficient (DSC). And the location differences of the GTVs were assessed using the center-of-mass distance between the two GTV groups.

Results:

A total of 47 lesions (volume range 0.02-21.48 mL) were outlined on magnetic resonance images of 9 patients with brain metastases. The mean GTV in TSE images ［(1.5833.870) mL］ was larger than that in IR-GRE images ［(1.4973.850) mL

P

＜0.001］. The DSC for the two GTV groups was 0.7960.102

and the distance between the centers of mass was (0.3290.323) mm.

Conclusion:

Volumetric and morphometric differences were found between the two groups of GTVs delineated on TSE and IR-GRE images

respectively. Considering that the TSE sequence offers better contrast enhancement and is less sensitive to the non-uniformity of the magnetic field

the GTV defined based on this sequence may be more accurate.