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  • Author or Editor: Georg Widhalm x
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Matthias Millesi, Barbara Kiesel, Mario Mischkulnig, Mauricio Martínez-Moreno, Adelheid Wöhrer, Stefan Wolfsberger, Engelbert Knosp and Georg Widhalm

OBJECTIVE

One of the most important causes for recurrence of intracranial meningiomas is residual tumor tissue that remains despite assumed complete resection. Recently, intraoperative visualization of meningioma tissue by 5-aminolevulinic acid (5-ALA)–induced protoporphyrin IX (PpIX) fluorescence was reported. The aim of this study was to investigate the possible surgical benefits of PpIX fluorescence for detection of meningioma tissue.

METHODS

5-ALA was administered preoperatively to 190 patients undergoing resection of 204 intracranial meningiomas. The meningiomas' PpIX fluorescence status, fluorescence quality (strong or vague), and intratumoral fluorescence homogeneity were investigated during surgery. Additionally, specific sites, including the dural tail, tumor-infiltrated bone flap, adjacent cortex, and potential satellite lesions, were analyzed for PpIX fluorescence in selected cases.

RESULTS

PpIX fluorescence was observed in 185 (91%) of 204 meningiomas. In the subgroup of sphenoorbital meningiomas (12 of 204 cases), the dural part showed visible PpIX fluorescence in 9 cases (75%), whereas the bony part did not show any PpIX fluorescence in 10 cases (83%). Of all fluorescing meningiomas, 168 (91%) showed strong PpIX fluorescence. Typically, most meningiomas demonstrated homogeneous fluorescence (75% of cases). No PpIX fluorescence was observed in any of the investigated 89 dural tails. In contrast, satellite lesions could be identified through PpIX fluorescence in 7 cases. Furthermore, tumor-infiltrated bone flaps could be visualized by PpIX fluorescence in all 13 cases. Notably, PpIX fluorescence was also present in the adjacent cortex in 20 (25%) of 80 analyzed cases.

CONCLUSIONS

The authors' data from this largest patient cohort to date indicate that PpIX fluorescence enables intraoperatively visualization of most intracranial meningiomas and allows identification of residual tumor tissue at specific sites. Thus, intraoperative detection of residual meningioma tissue by PpIX fluorescence might in future reduce the risk of recurrence.

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Matthias Millesi, Barbara Kiesel, Adelheid Woehrer, Johannes A. Hainfellner, Klaus Novak, Mauricio Martínez-Moreno, Stefan Wolfsberger, Engelbert Knosp and Georg Widhalm

Object

Subtotal resection (STR) of spinal tumors can result in tumor recurrence. Currently, no clinically reliable marker is available for intraoperative visualization of spinal tumor tissue. Protoporphyrin IX (PpIX) fluorescence induced by 5-aminolevulinic acid (5-ALA) is capable of visualizing malignant gliomas. Fluorescence-guided resections of malignant cerebral gliomas using 5-ALA have resulted in an increased rate of complete tumor removal. Recently, the application of 5-ALA has also been described in the first cases of spinal tumors. Therefore, the aim of this observational study was to systematically investigate 5-ALA–induced fluorescence characteristics in different spinal tumor entities.

Methods

Three hours before the induction of anesthesia, 5-ALA was administered to patients with different intra- and extradural spinal tumors. In all patients a neurosurgical resection or biopsy of the spinal tumor was performed under conventional white-light microscopy. During each surgery, the presence of PpIX fluorescence was additionally assessed using a modified neurosurgical microscope. At the end of an assumed gross-total resection (GTR) under white-light microscopy, a final inspection of the surgical cavity of fluorescing intramedullary tumors was performed to look for any remaining fluorescing foci. Histopathological tumor diagnosis was established according to the current WHO classification.

Results

Fifty-two patients with 55 spinal tumors were included in this study. Resection was performed in 50 of 55 cases, whereas 5 of 55 cases underwent biopsy. Gross-total resection was achieved in 37 cases, STR in 5, and partial resection in 8 cases. Protoporphyrin IX fluorescence was visible in 30 (55%) of 55 cases, but not in 25 (45%) of 55 cases. Positive PpIX fluorescence was mainly detected in ependymomas (12 of 12), meningiomas (12 of 12), hemangiopericytomas (3 of 3), and in drop metastases of primary CNS tumors (2 of 2). In contrast, none of the neurinomas (8 of 8), carcinoma metastases (5 of 5), and primary spinal gliomas (3 of 3; 1 pilocytic astrocytoma, 1 WHO Grade II astrocytoma, 1 WHO Grade III anaplastic oligoastrocytoma) revealed PpIX fluorescence. It is notable that residual fluorescing tumor foci were detected and subsequently resected in 4 of 8 intramedullary ependymomas despite assumed GTR under white-light microscopy.

Conclusions

In this study, 5-ALA–PpIX fluorescence was observed in spinal tumors, especially ependymomas, meningiomas, hemangiopericytomas, and drop metastases of primary CNS tumors. In cases of intramedullary tumors, 5-ALA–induced PpIX fluorescence is a useful tool for the detection of potential residual tumor foci.

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Barbara Kiesel, Matthias Millesi, Adelheid Woehrer, Julia Furtner, Anahita Bavand, Thomas Roetzer, Mario Mischkulnig, Stefan Wolfsberger, Matthias Preusser, Engelbert Knosp and Georg Widhalm

OBJECTIVE

Stereotactic needle biopsies are usually performed for histopathological confirmation of intracranial lymphomas to guide adequate treatment. During biopsy, intraoperative histopathology is an effective tool to avoid acquisition of nondiagnostic samples. In the last years, 5-aminolevulinic acid (5-ALA)–induced fluorescence has been increasingly used for visualization of diagnostic brain tumor tissue during stereotactic biopsies. Recently, visible fluorescence was reported in the first cases of intracranial lymphomas as well. The aim of this study is thus to investigate the technical and clinical utility of 5-ALA–induced fluorescence in a large series of stereotactic biopsies for intracranial lymphoma.

METHODS

This prospective study recruited adult patients who underwent frameless stereotactic needle biopsy for a radiologically suspected intracranial lymphoma after oral 5-ALA administration. During biopsy, samples from the tumor region were collected for histopathological analysis, and presence of fluorescence (strong, vague, or no fluorescence) was assessed with a modified neurosurgical microscope. In tumors with available biopsy samples from at least 2 different regions the intratumoral fluorescence homogeneity was additionally investigated. Furthermore, the influence of potential preoperative corticosteroid treatment or immunosuppression on fluorescence was analyzed. Histopathological tumor diagnosis was established and all collected biopsy samples were screened for diagnostic lymphoma tissue.

RESULTS

The final study cohort included 41 patients with intracranial lymphoma. Stereotactic biopsies with assistance of 5-ALA were technically feasible in all cases. Strong fluorescence was found as maximum level in 30 patients (75%), vague fluorescence in 2 patients (4%), and no visible fluorescence in 9 patients (21%). In 28 cases, samples were obtained from at least 2 different tumor regions; homogenous intratumoral fluorescence was found in 16 of those cases (57%) and inhomogeneous intratumoral fluorescence in 12 (43%). According to histopathological analysis, all samples with strong or vague fluorescence contained diagnostic lymphoma tissue, resulting in a positive predictive value of 100%. Analysis showed no influence of preoperative corticosteroids or immunosuppression on fluorescence.

CONCLUSIONS

The data obtained in this study demonstrate the technical and clinical utility of 5-ALA–induced fluorescence in stereotactic biopsies of intracranial lymphomas. Thus, 5-ALA can serve as a useful tool to select patients not requiring intraoperative histopathology, and its application should markedly reduce operation time and related costs in the future.

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Barbara Kiesel, Mario Mischkulnig, Adelheid Woehrer, Mauricio Martinez-Moreno, Matthias Millesi, Ammar Mallouhi, Thomas Czech, Matthias Preusser, Johannes A. Hainfellner, Stefan Wolfsberger, Engelbert Knosp and Georg Widhalm

OBJECTIVE

Glioblastoma (GBM) is characterized by distinct intratumoral histopathological heterogeneity with regard to variable tumor morphology, cell proliferation, and microvascularity. Maximum resection of a GBM results in an improved prognosis and thus represents the aim of surgery in the majority of cases. Fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA) is currently widely applied for improved intraoperative tumor visualization in patients with a GBM. Three intratumoral fluorescence levels (i.e., strong, vague, or no fluorescence) can usually be distinguished during surgery. So far, however, their exact histopathological correlates and their surgical relevance have not been clarified sufficiently. Thus, the aim of this study was to systematically analyze tissue samples from newly diagnosed GBMs with different fluorescence levels according to relevant histopathological parameters.

METHODS

This prospective study recruited patients who underwent 5-ALA fluorescence-guided resection of a newly diagnosed radiologically suspected GBM. Each patient received 5-ALA approximately 3 hours before surgery, and a modified neurosurgical microscope was applied for intraoperative visualization of 5-ALA–induced fluorescence. During surgery, tissue samples with strong, vague, or no fluorescence were collected. For each sample, the presence of tumor tissue, quality of tissue (compact, infiltrative, or no tumor), histopathological criteria of malignancy (cell density, nuclear pleomorphism, mitotic activity, and presence of microvascular proliferation/necrosis), proliferation rate (MIB-1 labeling index [LI]), and microvessel density (using CD34 staining) were investigated.

RESULTS

Altogether, 77 patients with a newly diagnosed, histopathologically confirmed GBM were included, and 131 samples with strong fluorescence, 69 samples with vague fluorescence, and 67 samples with no fluorescence were collected. Tumor tissue was detected in all 131 (100%) of the samples with strong fluorescence and in 65 (94%) of the 69 samples with vague fluorescence. However, mostly infiltrative tumor tissue was still found in 33 (49%) of 67 samples despite their lack of fluorescence. Strong fluorescence corresponded to compact tumors in 109 (83%) of 131 samples, whereas vague fluorescence was consistent with infiltrative tumors in 44 (64%) of 69 samples. In terms of the histopathological criteria of malignancy, a significant positive correlation of all analyzed parameters comprising cell density, nuclear pleomorphism, mitotic activity, microvascular proliferation, and necrosis with the 3 fluorescence levels was observed (p < 0.001). Furthermore, the proliferation rate significantly and positively correlated with strong (MIB-1 LI 28.3%), vague (MIB-1 LI 16.7%), and no (MIB-1 LI 8.8%) fluorescence (p < 0.001). Last, a significantly higher microvessel density was detected in samples with strong fluorescence (CD34 125.5 vessels/0.25 mm2) than in those with vague (CD34 82.8 vessels/0.25 mm2) or no (CD34 68.6 vessels/0.25 mm2) fluorescence (p < 0.001).

CONCLUSIONS

Strong and vague 5-ALA–induced fluorescence enables visualization of intratumoral areas with specific histopathological features and thus supports neurosurgeons in improving the extent of resection in patients with a newly diagnosed GBM. Despite the lack of fluorescence, tumor tissue was still observed in approximately half of the cases. To overcome this current limitation, the promising approach of complementary spectroscopic measurement of fluorescence should be investigated further.