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An effective MRI perfusion threshold based workflow to triage additional 18F-FET PET in posttreatment high grade
Krishna Ranjith Kadali1,2, Nathalie Nierobisch2, Fabienne Maibach2
1University of Zurich, Zurich, Switzerland.
Abstract:
MRI is the preferred method for follow-up imaging of post-treatment WHO grade 3 or 4 gliomas. While positron emission tomography with O-(2-[18F]fluoroethyl)-L-tyrosine) (18F-FET PET) offers higher diagnostic accuracy, its use is limited due to low availability. We propose a sequential, threshold-based workflow to triage patients for additional 18F-FET PET scans based on MRI dynamic susceptibility contrast (DSC) perfusion-derived rCBV values, to optimize 18F-FET PET resource allocation. Patients with high-grade gliomas who had undergone standard-of-care treatment and developed new or enlarging contrast-enhancing post-treatment lesions on MRI were included, with a 18F-FET PET study performed within 4 months of the MRI. Patients were excluded if there were significant changes in lesion size or treatment between the MRI and 18F-FET PET scan. An rCBV threshold was determined and the performance of a threshold-based imaging workflow was evaluated compared to the gold standard defined here as surgical verification or long-term imaging follow-up without further intervention. Forty-one patients with a total of 49 lesions were included (tumor progression n = 40, treatment-related changes n = 9). Above the rCBV threshold of 2.4, MRI was 100% accurate (21/21 patients) in diagnosing tumor progression. Below the threshold, MRI identified 9 true negatives but produced 19 false negatives. 18F-FET PET reclassified 18/19 (95%) false negatives resulting in an overall accuracy of 48/49 (98%) for the workflow. Our MRI DSC perfusion rCBV-based threshold workflow for triaging patients for additional 18F-FET PET imaging in post-treatment high grade glioma has the potential to optimize 18F-FET PET resource allocation.
Insights
A new MRI perfusion workflow accurately identifies high-grade glioma progression. This method uses a relative cerebral blood volume (rCBV) threshold to triage patients for 18F-FET PET scans, optimizing resource use.
Area of Science:
- Neuro-oncology
- Radiology
- Nuclear Medicine
Background:
- Magnetic Resonance Imaging (MRI) is standard for post-treatment high-grade glioma follow-up.
- 18F-FET PET offers superior diagnostic accuracy but faces availability limitations.
- Optimizing 18F-FET PET resource allocation is crucial for patient management.
Purpose of the Study:
- To develop and evaluate a sequential, threshold-based workflow for triaging patients for 18F-FET PET.
- To utilize MRI dynamic susceptibility contrast (DSC) perfusion-derived relative Cerebral Blood Volume (rCBV) values for triage.
- To enhance the efficiency of 18F-FET PET utilization in post-treatment glioma assessment.
Main Methods:
- Included patients with high-grade gliomas and contrast-enhancing lesions post-treatment.
- Assessed MRI DSC perfusion rCBV values against a determined threshold (2.4).
- Compared workflow accuracy against surgical verification or long-term imaging follow-up (gold standard).
Main Results:
- Above the rCBV threshold of 2.4, MRI accurately diagnosed tumor progression in 100% of cases (21/21).
- Below the threshold, MRI had 19 false negatives; 18F-FET PET reclassified 95% (18/19) of these.
- The proposed workflow achieved an overall accuracy of 98% (48/49 lesions).
Conclusions:
- An MRI DSC perfusion rCBV-based threshold workflow effectively triages patients for 18F-FET PET.
- This approach has the potential to significantly optimize 18F-FET PET resource allocation.
- Improved triage enhances diagnostic confidence in managing post-treatment high-grade gliomas.
