Figures 1, 2. On (1) T2-weighted fast spin-echo and (2) contrast-enhanced T1-weighted spin-echo images, the differential diagnosis between glioblastoma and abscess is impossible.
Figures 3, 4. (3) Diffusion-weighted (z sensitizing direction) multishot echo-planar image (800/123) obtained with five signals averaged and 6-mm section thickness and (4) corresponding ADC map show central hypointensity on diffusion-weighted image and hyperintensity on ADC map, consistent with the diagnosis of tumor.Tumors
Diffusion-weighted imaging has been used occasionally in the evaluation of intraaxial tumors. Brunberg et al(1) reported that apparent diffusion coefficient (ADC) and index of diffusion anisotropy determinations allow distinction between normal white matter areas and necrosis or cyst formation, edema, and solid enhancing tumor. Tien et al (2) found that areas of enhancing tumor were markedly hyperintense on diffusion-weighted images and that it was possible to distinguish areas of predominantly nonenhancing tumor from areas of predominantly peritumoral edema when the abnormality was located in the white matter aligned in the direction of the diffusion-weighted gradient.In our experience (3), diffusion-weighted imaging has little (if any) value in the differentiation between tumor and edema and, most important, in the detection of tumor invasion of white matter and edema when the differentiation cannot be done on conventional MR images. The behavior of inflammatory granulomas and abscesses on diffusion-weighted images may be used in differential diagnosis with necrotic tumors.In a case of multiple mucormucosis granulomas in a patient with acquired immunodeficiency syndrome, the lesions were hyperintense on diffusion-weighted images, with ADC values in the range of 0.39. In a case of streptococcus abscess, the hyperintensity on diffusion-weighted images was even higher, with a very low ADC value of 0.29 . This behavior allowed differential diagnosis with necrotic glioblastoma, which was suggested by clinical and conventional MR examinations.
Diffusion-weighted imaging has been used occasionally in the evaluation of intraaxial tumors. Brunberg et al(1) reported that apparent diffusion coefficient (ADC) and index of diffusion anisotropy determinations allow distinction between normal white matter areas and necrosis or cyst formation, edema, and solid enhancing tumor. Tien et al (2) found that areas of enhancing tumor were markedly hyperintense on diffusion-weighted images and that it was possible to distinguish areas of predominantly nonenhancing tumor from areas of predominantly peritumoral edema when the abnormality was located in the white matter aligned in the direction of the diffusion-weighted gradient.In our experience (3), diffusion-weighted imaging has little (if any) value in the differentiation between tumor and edema and, most important, in the detection of tumor invasion of white matter and edema when the differentiation cannot be done on conventional MR images. The behavior of inflammatory granulomas and abscesses on diffusion-weighted images may be used in differential diagnosis with necrotic tumors.In a case of multiple mucormucosis granulomas in a patient with acquired immunodeficiency syndrome, the lesions were hyperintense on diffusion-weighted images, with ADC values in the range of 0.39. In a case of streptococcus abscess, the hyperintensity on diffusion-weighted images was even higher, with a very low ADC value of 0.29 . This behavior allowed differential diagnosis with necrotic glioblastoma, which was suggested by clinical and conventional MR examinations.
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