Integration of ⁶⁸Ga-DOTA-TOC PET/CT into radiotherapy planning for intracranial meningiomas: A precision-imaging approach to tumor delineation.
Integrating 68Ga-DOTA-TOC PET/CT with conventional imaging may improve target delineation in radiotherapy planning for intracranial meningiomas, but further validation is needed.
Where it sits
this study against the rest of the octreotide corpusSummary and findings
This study evaluated the impact of integrating 68Ga-DOTA-TOC PET/CT with conventional imaging in radiotherapy planning for 25 patients with intracranial meningiomas. The integration aimed to improve target delineation, particularly in complex anatomical regions. Significant differences in gross tumor volumes were observed between imaging modalities.
Abstract
<h4>Background</h4>Accurate target delineation is critical for radiotherapy (RT) planning in intracranial meningiomas, particularly in complex anatomical regions such as the skull base or in postoperative settings. Meningiomas characteristically overexpress somatostatin receptor subtype-2 (SSTR2), allowing high-contrast molecular imaging with ⁶⁸Ga-DOTA-TOC PET/CT. This study evaluated the impact of integrating SSTR-PET with conventional imaging on RT target delineation in patients with intracranial meningiomas.<h4>Methods</h4>In this single-center observational study, 25 consecutive patients with intracranial meningioma undergoing radiotherapy planning underwent MRI and ⁶⁸Ga-DOTA-TOC PET/CT. Gross tumor volumes were delineated using MRI alone and PET-fused CT images. PET-derived biological tumor volume (BTV) was generated using a 40% SUVmax threshold. Semiquantitative PET parameters, SUVmax and tumor-to-background ratio (TBR), were recorded. Changes in GTV delineation following PET integration were analyzed.<h4>Results</h4>⁶⁸Ga-DOTA-TOC PET demonstrated intense SSTR expression (SUVmax 14.19 ± 10.88; TBRmax 83.48 ± 76.18) and precisely delineated tumor margins. PET identified osseous involvement in 40% of patients compared with 16% detected on MRI alone and revealed additional nonadjacent disease sites in 28% of cases. PET-based GTVs were significantly smaller than MRI-based volumes (12.01 ± 12.77 cm³ vs. 20.02 ± 18.71 cm³, p = 0.012). Integration of PET resulted in clinically relevant contour modification (> 5%) in 17 of 20 evaluable patients, including bone-specific adjustments in 12.<h4>Conclusion</h4>⁶⁸Ga-DOTA-TOC PET/CT demonstrated complementary value in radiotherapy planning for intracranial meningiomas, producing systematic geometric modifications in target volumes, with more frequent osseous involvement detection compared to MRI alone. These hypothesis-generating findings require validation in larger prospective multicenter studies with long-term clinical outcome endpoints before routine clinical adoption.
Background
Accurate target delineation is critical for radiotherapy planning in intracranial meningiomas, especially in complex anatomical regions. Meningiomas often overexpress somatostatin receptor subtype-2 (SSTR2), making them suitable for high-contrast imaging with 68Ga-DOTA-TOC PET/CT. This study investigates whether integrating SSTR-PET with conventional MRI improves the delineation of tumor targets in patients undergoing radiotherapy.
Methods
This was a single-center observational study involving 25 consecutive patients with intracranial meningiomas who were undergoing radiotherapy planning. Each patient underwent both MRI and 68Ga-DOTA-TOC PET/CT. Gross tumor volumes (GTV) were delineated using MRI alone and PET-fused CT images, with PET-derived biological tumor volume generated using a 40% SUVmax threshold.
Results
68Ga-DOTA-TOC PET demonstrated intense SSTR expression with an SUVmax of 14.19 ± 10.88. The integration of PET identified osseous involvement in 40% of patients, compared to 16% with MRI alone, and revealed additional nonadjacent disease sites in 28% of cases. PET-based GTVs were significantly smaller than MRI-based volumes, measuring 12.01 ± 12.77 cm³ versus 20.02 ± 18.71 cm³, with a p-value of 0.012.
Interpretation
The findings suggest that integrating PET imaging provides additional value in delineating tumor margins and detecting osseous involvement compared to MRI alone. While the statistical significance of the volume differences is noted, the clinical significance may be limited by the small sample size and the need for further validation in larger studies. The results imply that PET integration could enhance radiotherapy planning but should be approached cautiously until confirmed by more extensive research.
Key findings
- SUVmax 14.19 ± 10.88 for 68Ga-DOTA-TOC PET.
- TBRmax 83.48 ± 76.18.
- PET identified osseous involvement in 40% of patients compared with 16% detected on MRI alone.
- PET-based GTVs were significantly smaller than MRI-based volumes (12.01 ± 12.77 cm³ vs. 20.02 ± 18.71 cm³, p = 0.012).
- Integration of PET resulted in clinically relevant contour modification (> 5%) in 17 of 20 evaluable patients.
Limitations
- single-center study
- small sample size n=25
- observational design
- no long-term clinical outcome data