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Blood volume of gliomas determined by double-echo dynamic perfusion-weighted MR imaging: a preliminary study
Background And Purpose:
After bolus injection, gadopentetate dimeglumine causes a T2* rate change in permeable tissue that is contaminated by the T1 shortening effect due to the leakage of contrast agent. Therefore, tumor vascularity as reported in previous single-echo perfusion-weighted MR imaging studies has been underestimated. Our aim was to quantitatively and qualitatively evaluate the degree of blood volume of glioblastoma multiformes (GBMs) underestimated by this T1 shortening effect.
Methods:
We used double-echo dynamic MR imaging after a bolus injection of gadopentetate dimeglumine (double-echo perfusion-weighted MR imaging) to simultaneously determine tumor blood volume without (V(T1U)) and with (V(T1C)) T1 shortening correction. MR imaging was performed in five consecutive patients with GBMs. The ratios of V(T1U) and V(T1C) were calculated and compared by means of quantitative analysis. The degree of tumor blood volume as determined by V(T1U) and V(T1C) maps were qualitatively compared using a three-point scale.
Results:
All GBMs showed contrast enhancement on postcontrast T1-weighted images. In all subjects, the values of V(T1U) were significantly lower than those of V(T1C) (mean +/- SD, 2.05 +/- 1.01 vs. 3.62 +/- 1.40, respectively [P <.05]), indicating that tumor blood volume obtained by double-echo perfusion-weighted MR imaging was significantly higher than that by single-echo imaging. In the qualitative analysis, tumor blood volume on the V(T1U) map was less conspicuous than that on the V(T1C) map.
Conclusion:
Careful attention should be paid to the underestimation of tumor blood volume resulting from T1 shortening effects when using single-echo perfusion-weighted MR imaging. Double-echo imaging may be more suitable for the analysis of blood volume in GBMs.
Insights
Single-echo MRI underestimates glioblastoma blood volume due to contrast agent T1 shortening. Double-echo MRI provides a more accurate assessment of tumor vascularity in GBMs, overcoming this limitation.
Area of Science:
- Radiology
- Neuro-oncology
- Medical Imaging
Background:
- Gadolinium-based contrast agents cause T1 shortening in permeable tissues.
- This effect leads to underestimation of tumor vascularity in single-echo perfusion-weighted MRI.
- Glioblastoma multiforme (GBM) blood volume has been particularly affected by this underestimation.
Purpose of the Study:
- To quantitatively and qualitatively evaluate the underestimation of GBM blood volume.
- To assess the impact of T1 shortening on tumor vascularity measurements.
- To compare single-echo and double-echo MRI techniques for GBM blood volume assessment.
Main Methods:
- Utilized double-echo dynamic MRI after gadopentetate dimeglumine injection.
- Simultaneously determined tumor blood volume with (V(T1C)) and without (V(T1U)) T1 shortening correction.
- Performed quantitative analysis of V(T1U)/V(T1C) ratios and qualitative comparison of V(T1U) and V(T1C) maps in five GBM patients.
Main Results:
- All GBMs showed contrast enhancement.
- V(T1U) values were significantly lower than V(T1C) values (2.05 +/- 1.01 vs. 3.62 +/- 1.40, P <.05).
- Tumor blood volume was significantly higher with double-echo imaging; V(T1U) maps were less conspicuous than V(T1C) maps.
Conclusions:
- Single-echo perfusion-weighted MRI can underestimate GBM blood volume due to T1 shortening effects.
- Double-echo dynamic MRI offers a more accurate method for assessing blood volume in GBMs.
- Attention to T1 shortening is crucial for accurate tumor vascularity assessment in GBM patients.