Perfusion-sensitive MR imaging of gliomas: comparison between gradient-echo and spin-echo echo-planar imaging techniques

Abstract

Background and purpose: The different sensitivities to vessel size of gradient-echo echo-planar imaging (GE-EPI) and spin-echo EPI (SE-EPI) might indicate the relative cerebral blood volumes (rCBVs) of different tumor sizes. The techniques of GE-EPI and SE-EPI were compared for detecting low- versus high-grade gliomas.

Methods: Six patients with low-grade gliomas and 19 patients with high-grade gliomas underwent two perfusion-sensitive MR procedures, one produced by a GE- and the other by an SE-EPI technique. Maximum rCBV ratios normalized with rCBV of contralateral white matter were calculated for evaluation. P <.05 was considered statistically significant.

Results: Maximum rCBV ratios of high-grade gliomas obtained with the GE-EPI technique (mean, 5.0 +/- 2.9) were significantly higher than those obtained with the SE-EPI technique (mean, 2.9 +/- 2.3) (P =.02). Maximum rCBV ratios of low-grade gliomas obtained with the GE-EPI technique (mean, 1.2 +/- 0.7) were almost equal to those obtained with the SE-EPI technique (mean, 1.2 +/- 0.6), and there was no significant difference (P =.66). The difference in the maximum rCBV ratios between the low- and high-grade gliomas reached significance when obtained with the GE-EPI technique (P =.01).

Conclusion: The GE-EPI technique seems more useful for detecting low- versus high-grade gliomas than the SE-EPI technique.

fig 1.

Relationship of the maximum rCBV of the low- and high-grade gliomas between the GE- (2000/46/1 [TR/TE/excitation]) and the SE-EPI (2000/97/1) techniques. For high-grade gliomas, the maximum rCBV ratios obtained with GE-EPI are significantly higher than those acquired with SE-EPI, whereas there is no significant difference for low-grade gliomas

fig 2.

A 35-year-old man with low-grade astrocytoma. A, T2-weighted image at 3700/96/1 (TR/TE/excitation). Left frontoparietal tumor with hyperintensity is not enhanced after contrast medium administration. B, Contrast-enhanced T1-weighted image at 690/14/1. C and D, SE-EPI at 2000/97/1 (C) and GE-EPI (D,) at 2000/46/1. On the perfusion-sensitive MR imaging, tumor CBV (arrow) is lower than that of gray matter obtained with the two techniques.

fig 3.

A 55-year-old man with glioblastoma. A, Contrast-enhanced T1-weighted image at 690/14/1 (TR/TE/excitation). B and C, SE-EPI at 2000/97/1 (B) and GE-EPI at 2000/46/1 (C). The area of high tumor rCBV (arrow) is clearly visualized with both SE- and GE-EPI.

fig 4.

A 33-year-old man with glioblastoma. A, Contrast-enhanced T1-weighted image at 3700/96/1 (TR/TE/excitation). B and C, SE-EPI at 2000/97/1 (B) and GE-EPI (C) at 2000/46/1. High rCBV of the tumor rim (arrow) is shown with SE-EPI but is more conspicuous with GE-EPI (arrow).

fig 5.

The maximum rCBV ratios calculated with the GE-EPI technique at 2000/46/1 (TR/TE/excitation) versus those obtained with SE-EPI at 2000/97/1

fig 6.

A 47-year-old man with glioblastoma. A, Contrast-enhanced T1-weighted image at 3700/96/1 (TR/TE/excitation). B and C, SE-EPI at 2000/97/1 (B) and GE-EPI at 2000/46/1 (C). Tumor rCBV is higher than that of gray and white matter obtained with the two techniques, but the hypervascular area of the tumor (B and C, arrow) is more conspicuous with GE-EPI. D and E, The ΔR2* and ΔR2 curves during the transit of the contrast material through the gray and white matter regions of the brain and the two areas within the tumor that were measured using each of the SE- and GE-EPI techniques, respectively. The curves with white and black circles represent the tumor; the curves with squares and triangles represent the gray and white matter, respectively. Interestingly, the susceptibility effects within the tumor did not completely disappear after the first pass of the contrast medium on the GE-EPI image (D, arrow), whereas they almost completely disappeared on the SE-EPI image (E, arrow).

fig 6.

Continued