Dynamic contrast-enhanced T2*-weighted MR imaging of tumefactive demyelinating lesions

Abstract

Purpose: Dynamic contrast-enhanced T2*-weighted MR imaging has been helpful in characterizing intracranial mass lesions by providing information on vascularity. Tumefactive demyelinating lesions (TDLs) can mimic intracranial neoplasms on conventional MR images, can be difficult to diagnose, and often result in surgical biopsy for suspected tumor. The purpose of this study was to determine whether dynamic contrast-enhanced T2*-weighted MR imaging can be used to distinguish between TDLs and intracranial neoplasms that share common features on conventional MR images.

Methods: We retrospectively reviewed the conventional and dynamic contrast-enhanced T2*-weighted MR images and medical records of 10 patients with tumefactive demyelinating disease that was diagnosed by either biopsy or strong clinical suspicion supported by laboratory evaluation that included CSF analysis and evoked potential tests. Twelve TDLs in 10 patients and 11 brain tumors that appeared similar on conventional MR images were studied. Relative cerebral blood volume (rCBV) was calculated from dynamic MR data and was expressed as a ratio to contralateral normal white matter. rCBV values from 11 patients with intracranial neoplasms with very similar conventional MR imaging features were used for comparison.

Results: The rCBV values of TDLs ranged from 0.22 to 1.79 (n = 12), with a mean of 0.88 +/- 0.46 (SD). The rCBV values of intracranial neoplasms ranged from 1.55 to 19.20 (n = 11), with a mean of 6.47 +/- 6.52. The difference in rCBV values between the two groups was statistically significant (P =.009). The difference in rCBV values between TDLs and primary cerebral lymphomas (n = 4) was less pronounced but was statistically significant (P =.005).

Conclusion: Dynamic contrast-enhanced T2*-weighted MR imaging is a useful diagnostic tool in differentiating TDLs from intracranial neoplasms and may therefore obviate unnecessary surgical biopsy.

fig 1.

TDL in a 22-year-old woman. A, Contrast-enhanced T1-weighted image (600/14/1) shows a well-circumscribed solidly enhancing mass in the right frontal lobe. B, Fluid-attenuated inversion recovery image (9000/110/1) shows a mild degree of signal abnormality around the lesion. C, Color overlay of rCBV map shows no evidence of increased blood volume.

fig 2.

Glioblastoma multiforme in a 63-year-old woman. A, Contrast-enhanced T1-weighted image (600/14/1) shows a well-circumscribed mass in the left frontal lobe. B, T2-weighted image (3400/119/1) shows minimal edema and mass effect. C, Color overlay of rCBV map shows marked increase in blood volume.

fig 3.

TDL in a 37-year-old man. A, T2-weighted image (3400/119/1) shows a large hyperintense mass lesion in the right parietal lobe. There are no visible flow voids within the lesion. B, Unenhanced T1-weighted image (600/14/1) shows hypointense signal of the lesion. C, Contrast-enhanced T1-weighted image (600/14/1) shows heterogeneous enhancement of the medial aspect of the lesion in a concentric pattern. D, Dynamic T2*-weighted image (1000/54/1) obtained before IV administration of contrast agent. E, Dynamic T2*-weighted image (1000/54/1) obtained during IV administration of contrast agent shows several periventricular, linear vessel-like structures (arrows) running through the center of the lesion near a dilated subependymal vein. The dominant lesion itself shows no signal loss. F, Dynamic T2*-weighted image (1000/54/1) obtained 50 s after IV administration of contrast agent shows return of brain signal to baseline, with residual signal loss within the aforementioned linear vessel-like structures.