Intraoperative cerebral ultrasound for third ventricle colloid cyst removal: case report

"Dark corridors" in 5-ALA resection of high-grade gliomas: combining fluorescence-guided surgery and contrast-enhanced ultrasonography to better explore the surgical field

BACKGROUND

Increasing the extent of resection (EOR) is considered a main goal in high grade glioma (HGG) surgery. Significant advancements have been recently made to assist surgery: namely the use of 5-aminolevulinic acid (5ALA) and the application of contrast-enhanced ultrasound (CEUS) embody two of the most recently introduced tools in the neuro-oncology field. A combined approach including the two techniques has been suggested in literature. Our primary aim is to identify in which conditions CEUS final survey has a real impact in a 5-ALA guided context and assess which preoperative tumor characteristics, with specific attention to working corridors can predict strains of the fluorescence guided procedure and hence recommend the use of the combined technique.

METHODS

Forty-nine HGG glioma surgeries were performed at our institution with the abovementioned protocol between January 2016 and June 2016. Based on preoperative MRI, we stratified glioma characteristics according to three determinants: localization (deep versus superficial), size (<3.5 versus >3.5 cm) and shape (regular versus irregular).

RESULTS

CEUS modified 5-ALA guided resection in 11 cases (22.45%): this appeared to be associated with statistically significance to deep tumor localization (P=0.04) and irregular/multi-lobulated margins (P=0.003). On the other hand, tumor size alone did not appear as a statistically significant determinant.

CONCLUSIONS

When dark corridors are presents or when overlying brain parenchyma hinders illumination, drawbacks to the 5-ALA assistance can be expected, hence CEUS final survey has a crucial role of 'refinement'. In those selected cases, an integrated 5ALA+CEUS protocol was shown as advisable in EOR improvement.

5-Aminolevulinic Acid and Contrast-Enhanced Ultrasound: The Combination of the Two Techniques to Optimize the Extent of Resection in Glioblastoma Surgery

BACKGROUND

The survival benefit in maximizing resection in glioblastomas (GBMs) has been demonstrated by numerous studies. The true limit of infiltration of GBMs has been an overwhelming obstacle, and several technological advances have been introduced to improve the identification of residual tumors.

OBJECTIVE

To evaluate whether the integration of 5-aminolevulinic acid (5-ALA) with microbubble contrast-enhanced ultrasound (CEUS) improves residual tumor identification and has an impact on the extent of resection (EOR), overall survival (OS), and progression-free survival (PFS).

METHODS

A total of 230 GBM procedures were retrospectively studied. Cases were stratified according to the surgical procedure into 4 groups: 5-ALA- and CEUS-guided surgeries, 5-ALA-guided surgeries, CEUS-guided surgeries, and conventional microsurgical procedures.

RESULTS

Patients undergoing conventional microsurgical procedures showed the worst EORs compared to the assisted techniques (5-ALA and CEUS procedures). Both 5-ALA and CEUS techniques improved the EOR compared to conventional microsurgical procedures. However, their combination gave the best results in terms of the EOR (P = .0003). The median EOR% and the number of supramarginal resections are hence superior in the 5-ALA + CEUS + group compared to the others; this observation had consequences on PFS and OS in our series.

CONCLUSION

In terms of the EOR, the best results can be achieved through a combination of both techniques, where the 5-ALA-guided procedure is followed by a final survey with CEUS. Compared with other intraoperative imaging techniques, CEUS is a real-time, readily repeatable, safe, and inexpensive technique that provides valuable information to the surgeon before, during, and after resection.