Differential Chemosensitivity of Tumor Components in a Malignant Oligodendroglioma: Assessment with Diffusion-Weighted, Perfusion-Weighted, and Serial Volumetric MR Imaging
Hans Rolf Jägera,b,
Adam D Waldmana,c,
Christopher Bentona,
Nicholas Foxa and
Jeremy Reesa
a Institute of Neurology, National Hospital for Neurology and Neurosurgery, London, United Kingdom
b Lysholm Department of Neuroradiology, National Hospital for Neurology and Neurosurgery, London, United Kingdom
c Department of Imaging, Charing Cross Hospital, London, United Kingdom
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FIG 1. MR imaging study of a 37-year-old patient with a grade 3 oligodendroglioma before treatment.
A, Axial T2-weighted image (6000/105.5/2 [TR/TE/NEX]) at the level of the lateral ventricles shows a large heterogeneous tumor mass centered on the insular region and containing a complex cyst.
B and C, rCBV maps of a perfusion-weighted MR image obtained by using a dynamic susceptibility-weighted single shot echo planar sequence (1200/40/1) and 1 mmol/kg meglumine gadoterate bolus injected at a rate of 5 ml/s. B, Areas of increased rCBV (shown in red) are seen in the insular tumor portion. Measurements of the rCBV in that area ranged from 4.74 to 6.82 (mean, 5.49), by using the contralateral white matter as reference. C, There is no increased of rCBV in the temporal tumor portion, situated posterior to the right middle cerebral artery, which is a structure of a high blood volume and therefore shows up as red. The mean rCBV of the temporal tumor was 1.04.
D and E, ADC maps of a diffusion-weighted image (10,000/93.3 [TR/TE]; b = 1,000 s/mm2). D, Axial section at the level of the lateral ventricles shows that the tumor surrounding the complex cyst in right insular region appears hypointense relative to normal white matter. Regions of interest placed in this area had ADC measurements from 0.70 to 0.89 x 10–3 mm2/s (mean, 0.76) E, Axial section through the temporal lobes shows that the tumor in the right temporal lobe appears hyperintense relative to normal white matter, with ADC measurements ranging from 1.39 to 1.49 x 10–3 mm2/s (mean 1.44).
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FIG 2. MR imaging study following four cycles of chemotherapy with PCV.
A, Axial T2-weighted image (6000/105.5/2 [TR/TE/NEX]) at the level of the lateral ventricles shows a marked reduction of the insular tumor component with almost complete resolution of the complex cyst.
B, rCBV map of an axial dynamic susceptibility-weighted single shot echo planar sequence (1200/40/1 [TR/TE/NEX]) no longer show any areas of increased rCBV in the residual insular tumor.
C, ADC map of an axial diffusion-weighted image (10,000/93.3 [TR/TE]; b = 1000 s/mm2) at the level of the lateral ventricles shows that the small residual tumor in the insula is no longer hypointense but hyperintense compared with contralateral white matter, with ADC measurements ranging from 1.21 to 1.38 x 10–3 mm2/s (mean, 1.30).
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FIG 3. Difference image of volumetric pre- and post-treatment studies. Red-green difference image of pre- and post-treatment coregistered nonenhanced T1-weighted volumetric images (14.4/ 6.4/1[TR/TE/NEX]) with a section thickness of 1 mm. Green indicates a shift from lower to higher signal intensity between the first and second study; red, the reverse. Reduction in size of the superior (mostly insular) tumor component is shown in green, which indicates replacement of T1-hypointense tumor by tissue of higher signal intensity. Re-expansion of the hypointense CSF spaces because of a decrease in mass effect is indicated in red (this includes a track leading down to the right lateral ventricle, which is related to a previous biopsy). Note the absence of boundary shifts of the temporal tumor component between the pre- and post-treatment studies.
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