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Improving Diagnostic Robustness of Perfusion MRI in Brain Metastases: A Focus on 3D ROI Techniques and Automatic
Stéphanie Rudzinska-Mistarz1, Brieg Dissaux1,2, Laurie Marchi1
1Radiology Department, University Hospital, 29200 Brest, France.
Abstract:
Background: Distinguishing tumor recurrence from radiation necrosis after radiotherapy for brain metastases remains a major diagnostic challenge. Perfusion MRI, particularly the measurement of relative cerebral blood volume (rCBV), is a commonly used technique to differentiate between these two entities. However, variations in the placement of regions of interest (ROIs) affect diagnostic accuracy. This study compares the diagnostic performance of different cerebral perfusion methods, including a novel volumetric 3D ROI method and automatic thresholding, to differentiate tumor recurrence from radiation necrosis. Methods: We retrospectively analyzed data from 23 patients, including 25 brain metastases treated with stereotactic radiotherapy, who were suspected of local recurrence and had histological confirmation via biopsy or surgical resection. Each patient underwent perfusion MRI before surgery. The diagnostic performance of the different ROI methods (manual and 3D) was evaluated using the area under the ROC curve (AUC), as well as sensitivity and specificity measures. An automatic thresholding method was also applied, generating tumor sub-volumes with predefined cut-off values to determine the rCBV threshold most specific for differentiating relapse from necrosis. Results: The 3D ROI method, considering the whole lesion and a healthy ROI in the head of the caudate nucleus, demonstrated superior diagnostic performance (AUC = 0.65), outperforming manual methods (AUC = 0.53). Robustness was moderate, with an intraclass correlation coefficient of 0.60 between Syngo.via and IntelliSpace. Conclusions: The 3D ROI method shows promise in improving diagnostic accuracy in distinguishing tumor recurrence from radiation necrosis. Further studies with standardized protocols and larger populations are needed to validate these results.
Insights
A novel 3D region of interest (ROI) method for perfusion MRI shows improved accuracy in distinguishing brain tumor recurrence from radiation necrosis, outperforming traditional manual ROI techniques.
Area of Science:
- Neuro-oncology
- Radiology
- Medical Imaging
Background:
- Differentiating tumor recurrence from radiation necrosis post-radiotherapy for brain metastases is diagnostically challenging.
- Perfusion MRI, specifically relative cerebral blood volume (rCBV) measurement, is utilized but sensitive to region of interest (ROI) placement variability.
- Accurate differentiation is crucial for appropriate patient management and treatment planning.
Purpose of the Study:
- To compare the diagnostic performance of different cerebral perfusion MRI methods, including a novel volumetric 3D ROI approach and automatic thresholding.
- To evaluate the effectiveness of these methods in distinguishing between tumor recurrence and radiation necrosis.
- To identify an optimal rCBV threshold for differentiating relapse from necrosis.
Main Methods:
- Retrospective analysis of 23 patients with 25 brain metastases treated with stereotactic radiotherapy.
- Perfusion MRI was performed before biopsy or surgical resection for histological confirmation.
- Diagnostic performance was assessed using area under the ROC curve (AUC), sensitivity, and specificity for manual and 3D ROI methods, alongside an automatic thresholding technique.
Main Results:
- The 3D ROI method, incorporating the entire lesion and a healthy caudate nucleus ROI, achieved superior diagnostic performance with an AUC of 0.65 compared to manual methods (AUC = 0.53).
- Moderate robustness was observed, with an intraclass correlation coefficient of 0.60 between different software platforms.
- Automatic thresholding generated tumor sub-volumes to identify specific rCBV cut-off values.
Conclusions:
- The volumetric 3D ROI method demonstrates potential for enhancing diagnostic accuracy in differentiating tumor recurrence from radiation necrosis.
- Further validation with standardized protocols and larger patient cohorts is recommended.
- This technique may offer a more reliable approach to perfusion MRI analysis in neuro-oncology.
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