PMC6813201_01
(A-C) Coronal, midsagittal, and axial T1-weighted post-contrast MRI images of the patient's two parasagittal, enhancing, extradural lesions; both lesions are seen to invade the superior sagittal sinus, particularly the left parasagittal parietal lesion in (B) which also shows evidence of osseous extension. (D) Axial T2-FLAIR-weighted sequence showing extensive peri-lesional vasogenic edema of both the right and left parasagittal lesions, worse on the left. (E) Diffusion-weighted imaging demonstrating evidence of diffusion restriction within the larger, left parasagittal parietal lesion reflecting high cellular density in the tumor (later determined to be a WHO grade II atypical meningioma). (F) Gradient echo (GRE) sequence showing sparsely scattered areas of signal dropout indicative of calcifications, particularly in the right frontal lesion, but no evidence of hemosiderin deposits or other evidence of intratumoral hemorrhage in either lesion.
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F1
MRI showed the extra-axial lesions to be contrast-enhancing and most consistent with meningioma, especially given an otherwise negative metastatic workup (Figures 1A-C). Both lesions showed diffusion restriction, surrounding vasogenic edema, and irregular borders (Figures 1D,E). Gradient echo sequence showed no evidence of intratumoral hemorrhage in either lesion (Figure 1F). The left-sided lesion invaded the superior sagittal sinus and adjacent calvarium suggesting intraosseous extension (Figure 1B).
(Left) IMRT treatment planning image. Isodose lines are displayed on post-operative axial CT scan. The targeted total dose (red) is shaped around the remainder of the posterior parasagittal meningioma. The right frontal meningioma can be seen within the lighter blue Isodose line, indicating a potential overall dose between 11.7 and 17.6 Gy. (Right) Isodose legend with corresponding percent total planned radiation dose and actual radiation dose to be given over 30 fractions.
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He received a total targeted dose of 54 Gy in 30 fractions over 6 weeks (Figure 2).
Serial axial (top panels) and coronal (bottom panels) T1-weighted post-contrast MRI images taken every 6 months during outpatient follow-up, including the initial post-operative scan showing parasagittal parietal meningioma invading the superior sagittal sinus left as residual tumor. Follow-up scans at 6 months, 1 year, and 1.5 years show that the two lesions remained stable in size. On 2-year through the most recently taken 3.5-year scans, regression of both the left parasagittal parietal and the (untreated) right frontal lesions is visualized and attributed to the abscopal effect. A CT scan was performed for follow-up at 3.5 years due to recent placement of a non-MRI-compatible cardiac pacer.
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MRIs at 6 months, 1 year, and 1.5 years post-treatment were grossly stable (Figure 3). This regression trend continued through to 3 years (L 2.6 x 2.0 x 1.9 cm, R 3.2 x 3.1 x 2.6 cm) and to most recent follow-up with CT scan at 3.5 years (L 2.4 x 2.3 x 1.4 cm, R 3.1 x 3.0 x 1.9 cm), at which point significantly reduced surrounding edema around the right frontal lesion was also noted (Figure 3).