gms | German Medical Science

Objective: To examine the feasibility of routine perfusion-weighted intraoperative MR imaging (iMRI) and to evaluate its usefulness as an aid to detect the residual tumor and and maximise the tumour resection extent.

Method: Twenty-eight patients underwent perfusion-weighted iMRI (in a dual-room 1.5-T magnet setting) after contrast agent administration in order to evaluate the resection of high-grade gliomas. The generated relative cerebral blood volume (rCBV) maps were superimposed in the diagnostic T1-weighted images and were scrutinised for any hyper-perfused regions, indicative of tumour remnants. A hand-drawn region-of-interest (ROI) analysis was performed in order to detect differences between the rCBV values in suspected residual tumour, free tumour margins and normal white matter. Using neuronavigation, tissue specimens from the suspected areas were sampled and referred to histopathology.

Results: Artefact-free rCBV perfusion maps were generated in all cases. The lack of any hyper-perfused areas was consistent with macroscopically as well as histopathologically verified gross total resection of gliomas in 7 cases. However, in 21 cases, the perfusion-weighted iMRI revealed "hot-spots" indicating hyper-perfused tumour residuums after subtotal tumour removal. The latter proved to be histologically true in all but one case. Therefore, the diagnostic performance of the qualitative visual and the quantitative analysis showed excellent sensitivity and specificity rates. Statistically significant differences for mean rCBV and maximum rCBV were demonstrated between residual tumour and tumour free surgical margins, (P = .0017) and (P = .0021) respectively.

Conclusions: The perfusion-weighted imaging is feasible in the intraoperative MR suite and can be easily implemented in the routine MRI protocols. The perfusion iMRI findings may assist the surgeon in detecting residual tumor volume and achieving a total tumour resection.