Article
Multimodal preoperative MR-imaging in patients with presumed low grade gliomas in eloquent language areas – implications for targeted surgical resection
Multimodale präoperative MRT-Bildgebung bei Patienten mit niedriggradigen Gliomen in der Nähe des spracheloquenten Cortex – Implikationen für eine gezielte chirurgische Resektion
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Published: | May 30, 2008 |
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Objective: To analyze the value of preoperative multimodal MR-imaging (1H MR-spectroscopy [1H MRS], fMRI, CBF) in patients with dominant hemisphere gliomas in close relation to language areas with respect to surgical treatment strategy.
Methods: Data derived from a prospective series of 19 consecutive patients with newly diagnosed gliomas in the dominant hemisphere in close relation to anatomical language areas treated between November 2005 and November 2007. Mean patient’s age was 45±12 years and 12 patients were male (63%). All patients underwent awake craniotomy for intraoperative language testing (counting, naming, action naming) and at least partial tumour resection according to intraoperative stimulation results. Data of multimodal preoperative imaging was implemented in surgical navigation (Brain Lab, Germany). Signs of focal tumour dedifferentiation were considered in cases of partial contrast enhancement in standard MRI, increased cholin in 1H MRS and increased regional cerebral blood flow (rCBF) in perfusion weighted MRI. In patients with extended tumours and limited surgical treatment option the intended surgical goal was to remove at least the suspected dedifferentiated tumour part defined by preoperative multimodal MR imaging.
Results: According to standard preoperative MRI 8 patients had signs suspicious of focal malignant tumour dedifferentiation. In addition in 9 patients 1H MRS and rCBF measurement indicated focal malignant transformation. Although complete surgical resection of the tumours was deemed impossible due to intraoperative language test results the dedifferentiated tumour part could be completely removed in all patients as proven by postoperative MRI. A temporary decrease in language function was seen in 16 patients (84%) but resolved within 1 week in 14 of them. In 13 of the patients with targeted resection histology proved malignant transformation and therefore these patients underwent adjuvant treatment.
Conclusions: Multimodal preoperative MR- imaging is helpful to detect focal malignant tumour transformation missed in standard diagnostic MRI in patients with presumed low grade gliomas. In patients in which complete resection is precluded due to infiltration of functional language areas a targeted resection of the dedifferentiated tumour part(s) is a prerequisite for adequate histological diagnosis. However, long-term follow-up assessment is necessary to show, whether or not targeted resection of malignant tumour parts and adjuvant treatment prolongs survival in these patients.