Vermandel M, Leroy H-A, Dupont C, Mordon S, Reyns N
Magnetic resonance imaging to assess photodynamic therapy effects on a preclinical model: preliminary results on diffusion/perfusion MRI to evaluate PDT response
ASLMS 2017, San Diego, CA
Magnetic resonance imaging to assess photodynamic therapy effects on a preclinical model: preliminary results on diffusion/perfusion MRI to evaluate PDT response
ASLMS 2017, San Diego, CA
Abstract:
Background
Glioblastoma (GBM) is a malignant brain tumor with a particularly dismal prognosis (overall median survival lower than 16 months). Despite of GBM is a rare neoplastic disease with low prevalence (0.3/10,000 persons), it remains the most frequent malignant primary brain tumor in adults. Today, 5-ALA PDT, either delivered interstitially or intraoperatively, has recently been reported to have potential effective outcomes in patients harboring GBM. Recent studies reported the outcomes of PDT delivered to GBM using preclinical immunohistological data. Our study aims to evaluate the role of MRI imaging, including diffusion and perfusion, for monitoring PDT effects early after treatment and for different illumination regimen.
Study Design/Materials and Method
“Nude” rats were grafted with human U87 cells into the right putamen. After 5-ALA intake, an optic fiber was introduced into the tumor. The rats were randomized in three groups: without illumination, with two-fraction lighting or five-fraction lighting for a total dose of 25 J at 30mW/cm2. Treatment effects were assessed with early MRI including diffusion and perfusion sequences and compared to immunohistology.
Results
Images acquired on a 7 Tesla MRI revealed an elevated diffusion values in the center of the tumor and a decreased perfusion around the treatment site among treated animals, especially in 5-fraction group. These observations were in agreement with histology. Indeed, diffusion was a relevant marker of necrosis and apoptosis and perfusion well described the level of necrosis. Additionally, T2 signal was correlated with inflammation/edema observed on histology.
Conclusion
We observed that diffusion and perfusion MRI were able to assess PDT effects. Diffusion and perfusion MRI were good biomarkers of the histological lesions. Indeed, interstitial PDT induced specific tumor lesions observed with MRI were confirmed from histopathology study. Finally, MRI might provide a non-invasive and reliable tool to assess treatment outcomes early after PDT.
Background
Glioblastoma (GBM) is a malignant brain tumor with a particularly dismal prognosis (overall median survival lower than 16 months). Despite of GBM is a rare neoplastic disease with low prevalence (0.3/10,000 persons), it remains the most frequent malignant primary brain tumor in adults. Today, 5-ALA PDT, either delivered interstitially or intraoperatively, has recently been reported to have potential effective outcomes in patients harboring GBM. Recent studies reported the outcomes of PDT delivered to GBM using preclinical immunohistological data. Our study aims to evaluate the role of MRI imaging, including diffusion and perfusion, for monitoring PDT effects early after treatment and for different illumination regimen.
Study Design/Materials and Method
“Nude” rats were grafted with human U87 cells into the right putamen. After 5-ALA intake, an optic fiber was introduced into the tumor. The rats were randomized in three groups: without illumination, with two-fraction lighting or five-fraction lighting for a total dose of 25 J at 30mW/cm2. Treatment effects were assessed with early MRI including diffusion and perfusion sequences and compared to immunohistology.
Results
Images acquired on a 7 Tesla MRI revealed an elevated diffusion values in the center of the tumor and a decreased perfusion around the treatment site among treated animals, especially in 5-fraction group. These observations were in agreement with histology. Indeed, diffusion was a relevant marker of necrosis and apoptosis and perfusion well described the level of necrosis. Additionally, T2 signal was correlated with inflammation/edema observed on histology.
Conclusion
We observed that diffusion and perfusion MRI were able to assess PDT effects. Diffusion and perfusion MRI were good biomarkers of the histological lesions. Indeed, interstitial PDT induced specific tumor lesions observed with MRI were confirmed from histopathology study. Finally, MRI might provide a non-invasive and reliable tool to assess treatment outcomes early after PDT.
