PMC2948920_01
Imaging results for Case 1. (a) Contrast-enhanced MRI showing heterogeneous or ring-like enhancement in the temporal lobe. The elliptical area indicates the cortical incision, via which tumor resection was performed. (b) Axial T2WI showing the tumor resection zone. The cortical tissue located on the surface of the temporal lobe was not resected. (c) CT revealing cyst formation in the tumor resection cavity 3 days after tumor resection. The arrow indicates the position of the "valve"-like structure. (d) Relief of effusion in the tumor resection cavity following the reoperation. The arrow indicates the opening of the roof region of the tumor resection cavity and the disappearance of the "valve"-like structure. (e) Recommencement of effusion in the tumor resection cavity 5 days after the reoperation. The roof region of the tumor resection cavity was sealed again, indicating possible reformation of the "valve"-like structure. (f) Recommencement of effusion in the tumor cavity 1 week after the second reoperation removing the bone flap. (g) Disappearance of cyst formation in the tumor resection cavity 3 months after the second reoperation.
CRM2010-634839.001.jpg
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fig1
After administration of contrast agent, the lesion showed patchy heterogeneous enhancement or ring enhancement (Figures 1(a) and 1(b)). Figure 1(a)) was made in the sylvian fissure. Further intraoperative exploration showed that the blood supply to the tumor was provided by small branches of the middle cerebral artery. The cortical tissue located on the surface of the temporal lobe was not resected (the extent of tumor resection was limited to the elliptical area shown in Figure 1(b)). Therefore, cyst formation in the tumor resection cavity was indicated (Figure 1(c)). A "valve"-like structure was formed by relocated cerebral tissue, Surgicel, and the arachnoid in the roof region of the tumor cavity, sealing the effusion in the tumor resection cavity (the position of the "valve"-like structure is shown by the arrow in Figure 1(c)). Postoperative CT reexamination revealed that the space-occupying effect was absent, the roof region of the tumor resection cavity was open, and the "valve"-like structure had disappeared (as shown by the arrow in Figure 1(d)).  Repeat CT showed a recommencement of effusion in the tumor resection cavity and resealing of the roof region of the tumor resection cavity, suggesting possible reformation of the "valve"-like structure (Figure 1(e)). One week later, a CT rescan of her head demonstrated that there was still effusion in the tumor resection cavity, and it was possible that the "valve"-like structure had reformed again (Figure 1(f)). Three months later, CT examination showed that the cyst formation in the tumor resection cavity had disappeared, and the tumor had not recurred (Figure 1(g)).
PMC2948920_02
Imaging results for Case 2. (a)-(b) MRI showing sphenoid ridge meningioma. (c) CT revealing cyst formation in the tumor resection cavity 6 days after tumor resection. The arrow indicates the narrow roof region of the tumor resection cavity, where the "valve"-like structure is located. (d) Recommencement of effusion in the tumor cavity 1 week after the reoperation. The arrow indicates that the roof region of the tumor resection cavity became widened. (e)-(g) MRI showing disappearance of cyst formation in the tumor resection cavity 10 months after the reoperation.
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fig2
After contrast administration, the lesion showed heterogeneous enhancement (Figures 2(a) and 2(b)). A band-shaped hyperintense shadow was noted in the intracranial subdural space, in which some shadows of gas density were scattered (Figure 2(c)). The location of the "valve"-like structure was along the sylvian fissure between the inferior frontal gyrus and superior temporal gyrus after the sphenoid ridge (the position of the "valve"-like structure is near the arrow shown in Figure 2(c)) the length along the sylvian fissure was about 5 cm. But the roof region of the tumor resection cavity had become wider than before (as shown by the arrow in Figure 2(d)). Ten months later, MRI examination showed that the cyst formation in the tumor resection cavity had disappeared, and the tumor had not recurred (Figures 2(e)-2(g)).