Perfusion weighted magnetic resonance imaging to distinguish the recurrence of metastatic brain tumors from radiation necrosis after stereotactic radiosurgery

Abstract

After stereotactic radiosurgery (SRS) for brain metastases, delayed radiation effects with mass effect may occur from several months to years later, when tumors may also recur. Aggressive salvage treatment would be beneficial for patients with recurrence, but may be contraindicated for those with dominant radiation effect. Conventional magnetic resonance (MR) imaging does not provide sufficient information to differentiate delayed radiation effects from tumor recurrence. Positron emission tomography, MR spectroscopy, and other modalities sometimes may lead to false findings of tumor recurrence. We prospectively applied perfusion MR imaging for the management strategy after SRS because it gives microvascular information about the lesions. Twenty-eight lesions were enlarged on serial MR images in 27 patients 2-35 months (median: 11.8 months) after SRS for metastatic brain tumors. Each patient underwent MR perfusion imaging within a month after appearance of the growing enhanced lesion. To calculate the relative cerebral blood volume ratio (rCBV ratio), the regions of interest were located in the enhanced areas on the contrast-enhanced T1-weighted images and compared with the corresponding contralateral normal brain tissue. They were then followed-up with scheduled MR images with gadolinium enhancement at 1 to 2-month intervals afterward. Lesions which progressively increased in size on MR images were diagnosed as recurrences; lesions which disappeared or decreased in size were diagnosed as radiation necrosis. In addition, two lesions surgically removed were diagnosed by pathological examination. Follow-up MR images revealed that 21 of 28 lesions were radiation necrosis. Five lesions were diagnosed as recurrence on MR images, and the other two lesions were revealed as recurrence by pathological examination. An rCBV ratio of greater than 2.1 provided the best sensitivity and specificity for identifying recurrent metastatic tumors, at 100 and 95.2%, respectively. Perfusion MR imaging provides useful, less invasive and in-vivo information for management of growing lesions after SRS, and rCBV may be a valuable index for this diagnostic purpose.

Accuracy of F-DOPA PET and perfusion-MRI for differentiating radionecrotic from progressive brain metastases after radiosurgery

“…Nonstandard MRI sequences, including diffusion, perfusion-weighted and spectroscopy have been used to differentiate RN from PD. In particular, several reports have indicated that the relative cerebral blood volume (rCBV), derived from perfusionweighted sequences, can differentiate RN from PD with high accuracy [15,16]. In addition to MRI, radionuclide imaging with either single photon [17] or positron emitters [18][19][20] has also been tested in this setting.…”

Diagnostic Accuracy of PET, SPECT, and Arterial Spin-Labeling in Differentiating Tumor Recurrence from Necrosis in Cerebral Metastasis after Stereotactic Radiosurgery

“…For brain metastases, DSC-MR imaging yielded sensitivity and specificity values from 70% to 100% and 95.2% to 100% for differentiation of necrosis and tumor recurrence. 25,26 In differentiating tumor recurrence and radiation necrosis or pseudoprogression of primary gliomas, direct comparison between ASL and DSC-MR imaging showed no statistical significance, with sensitivity and specificity values of 79%-94% and 64%-88%. 20,27 In terms of detection of gliomas and metastases, ASL and DSC-MR imaging also showed similar diagnostic yields.…”

Conventional and contrast-enhanced ultrasound assessment of craniocerebral gunshot wounds

“…MRI diffusion-and perfusion-weighted imaging are the most rapid and accurate techniques (Mitsuya et al, 2010). However, for patients who are immobile and those with acute craniocerebral gunshot injuries, CEUS prove valuable in the absence of MRI or when rapid intervention is necessary.…”