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

PURPOSE: Dynamic contrast-enhanced T2*-weighted MR imaging has been helpful in characterizing intracranial mass lesions by providing information on va scularity. Tumefactive demyelinating lesions (TDLs) can mimic intracranial neoplasms on conventional MR images, can be difficult to diagnose, and ofte n 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 sha re 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 tum efactive demyelinating disease that was diagnosed by either biopsy or stron g clinical suspicion supported by laboratory evaluation that included CSF a nalysis and evoked potential tests. Twelve TDLs in 10 patients and 11 brain tumors that appeared similar on conventional MR images were studied. Relat ive cerebral blood volume (rCBV) was calculated from dynamic MR data and wa s expressed as a ratio to contralateral normal white matter. rCBV values fr om 11 patients with intracranial neoplasms with very similar conventional M R 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 +/- 0.36 (SD). The rCBV values of intracranial neoplasms range d 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 lymph omas (n = 4) was less pronounced but was statistically significant (P = .00 5). CONCLUSION: Dynamic contrast-enhanced T2*-weighted MR imaging is a useful d iagnostic tool in differentiating TDLs from intracranial neoplasms and may therefore obviate unnecessary surgical biopsy.