Diffusion-Weighted Imaging of Radiation-Induced Brain Injury for Differentiation from Tumor Recurrence
Chiaki Asaoa,
Yukunori Korogic,
Mika Kitajimaa,b,
Toshinori Hiraia,
Yuji Babaa,
Keishi Makinob,
Masato Kochia,
Shoji Morishitaa and
Yasuyuki Yamashitaa
a Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
b Department of Neurosurgery, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
c Department of Radiology, University of Occupational and Environmental Health, School of Medicine, 1-1 Iseigaoka, Kitakyushu 807-8555, Japan
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FIG 1. Images obtained in a 54-year-old man with biopsy-proven radiation necrosis after receiving radiation and chemotherapy for anaplastic oligodendroglioma.
A, Gadolinium-enhanced T1WI image shows an irregular ring-enhancing lesion with mass effect.
B, DWI image obtained at the same level as A shows a mixed SI pattern (arrowheads), with marked hypointensity (arrow), which is typical for radiation necrosis. Radiation necrosis may have a variety of SI patterns on DWI images, reflecting the development of necrosis. Marked DWI hypointensity is probably attributable to liquefactions in late-stage necrosis.
C, ADC map, which corresponds to B, shows a mixed SI pattern, with a markedly high ADC value (arrow).
D and E, Histopathological specimens (hematoxylin-eosin, x20 [D], x40 [E]) show total parenchymal necrosis with hemorrhage. No evidence of viable tumor cells was found.
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FIG 2. Images obtained in a 53-year-old woman with biopsy-proven tumor after receiving radiation and chemotherapy for anaplastic astrocytoma.
A, Gadolinium-enhanced T1WI image shows a ring-enhancing lesion with a solid enhancing component in the left temporal lobe. Multiple patchy enhancements with mass effect are also seen in the left basal ganglia and insula, suggestive of tumor infiltration.
B, DWI image obtained at the same level as that of A shows the solid enhancing component of predominant hyperintensity (arrows), which usually represents densely packed tumor cells.
C, ADC map, which shows the relatively low apparent diffusion coefficient value of the lesion (arrows).
D and E, Histopathological specimens (hematoxylin-eosin, x20 [D], x80 [E]) show tumor tissues with increased cellular density corresponding to anaplastic astrocytoma. No evidence of necrotic tissue was found.
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FIG 3. A comparison of each ADC value between radiation necrosis and recurrence. The maximal and mean ADC values of each lesion were lower for the recurrence group than for the necrosis group; however, the difference between the 2 groups was significant only for the maximal ADC values.
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