Related Experiment Video
Updated: Aug 5, 2025
Author Spotlight: Noninvasive Cerebral Blood Flow Determination in Human Functional Brain Region for Diagnosis of Neurological Disorders
Published on: May 31, 2024
Clinical utility of intraoperative arterial spin labeling for resection control in brain tumor surgery at 3 T
Marta Calvo-Imirizaldu1, Verónica Aramendía-Vidaurreta1,2, Carmen Sánchez-Albardíaz1
1Radiology Department, Clínica Universidad de Navarra, Pamplona, Spain.
Abstract:
Resection control in brain tumor surgery can be achieved in real time with intraoperative MRI (iMRI). Arterial spin labeling (ASL), a technique that measures cerebral blood flow (CBF) non-invasively without the use of intravenous contrast agents, can be performed intraoperatively, providing morpho-physiological information. This study aimed to evaluate the feasibility, image quality and potential to depict residual tumor of a pseudo-continuous ASL (PCASL) sequence at 3 T. Seventeen patients with brain tumors, primary (16) or metastatic (1), undergoing resection surgery with iMRI monitoring, were prospectively recruited (nine men, age 56 ± 16.6 years). A PCASL sequence with long labeling duration (3000 ms) and postlabeling delay (2000 ms) was added to the conventional protocol, which consisted of pre- and postcontrast 3D T1 -weighted (T1w) images, optional 3D-FLAIR, and diffusion. Three observers independently assessed the image quality (four-point scale) of PCASL-derived CBF maps. In those with diagnostic quality (Scores 2-4) they evaluated the presence of residual tumor using the conventional sequences first, and the CBF maps afterwards (three-point scale). Inter-observer agreement for image quality and the presence of residual tumor was assessed using Fleiss kappa statistics. The intraoperative CBF ratio of the surgical margins (i.e., perilesional CBF values normalized to contralateral gray matter CBF) was compared with preoperative CBF ratio within the tumor (Wilcoxon's test). Diagnostic ASL image quality was observed in 94.1% of patients (interobserver Fleiss κ = 0.76). PCASL showed additional foci suggestive of high-grade residual component in three patients, and a hyperperfused area extending outside the enhancing component in one patient. Interobserver agreement was almost perfect in the evaluation of residual tumor with the conventional sequences (Fleiss κ = 0.92) and substantial for PCASL (Fleiss κ = 0.80). No significant differences were found between pre and intraoperative CBF ratios (p = 0.578) in patients with residual tumor (n = 7). iMRI-PCASL perfusion is feasible at 3 T and is useful for the intraoperative assessment of residual tumor, providing in some cases additional information to the conventional sequences.
Insights
Intraoperative MRI with pseudo-continuous arterial spin labeling (PCASL) is feasible for brain tumor surgery. This technique provides valuable information on cerebral blood flow to help assess residual tumor during surgery.
Area of Science:
- Neurosurgery
- Radiology
- Medical Imaging
Background:
- Real-time resection control in brain tumor surgery is crucial and can be achieved with intraoperative MRI (iMRI).
- Arterial spin labeling (ASL) offers non-invasive, contrast-agent-free measurement of cerebral blood flow (CBF), providing vital morpho-physiological data.
- Intraoperative ASL can enhance surgical decision-making by visualizing tumor characteristics.
Purpose of the Study:
- To evaluate the feasibility, image quality, and residual tumor depiction capabilities of a pseudo-continuous ASL (PCASL) sequence at 3 Tesla during iMRI.
- To assess the utility of PCASL in identifying residual tumor components not evident with conventional iMRI sequences.
Main Methods:
- A prospective study involving 17 brain tumor patients undergoing iMRI-monitored resection.
- A PCASL sequence was integrated into the iMRI protocol, alongside standard T1-weighted and diffusion-weighted imaging.
- Independent observers assessed PCASL-derived CBF map quality and residual tumor presence, with inter-observer agreement analyzed using Fleiss kappa statistics.
Main Results:
- Diagnostic image quality for PCASL was achieved in 94.1% of patients, with substantial inter-observer agreement (κ=0.76).
- PCASL identified additional high-grade residual tumor foci in three patients and revealed a hyperperfused area beyond the enhancing tumor margin in one patient.
- Inter-observer agreement for residual tumor detection was almost perfect with conventional sequences (κ=0.92) and substantial with PCASL (κ=0.80).
Conclusions:
- Intraoperative MRI with PCASL perfusion at 3T is feasible and effective for assessing residual brain tumor during surgery.
- PCASL provides valuable perfusion information, offering supplementary data to conventional sequences for improved intraoperative decision-making.
- This technique enhances the ability to achieve complete tumor resection by visualizing critical vascularity.
