At the Clinical Trials on Alzheimer’s Disease (CTAD) conference, Miguel Rosa-Grilo from University College London presented a novel approach to MRI scanning that significantly reduces scan times without sacrificing image quality. The new method, leveraging Wave-Controlled Aliasing in Parallel Imaging (Wave-CAIPI), could alleviate bottlenecks in Alzheimer’s diagnosis and monitoring, particularly with the increasing demand for scans due to new Alzheimer's treatments.
Tripling Scan Speed with Wave-CAIPI
Rosa-Grilo's team integrated Wave-CAIPI into the standard diagnostic MRI protocol used at UCL's memory clinic. This protocol includes T1-weighted 3D, T2-weighted 2D, T2-weighted 3D, and 3D FLAIR imaging. By incorporating Wave-CAIPI, the total scan time was reduced from nearly 18 minutes to just 6.5 minutes.
Wave-CAIPI, developed in 2015 at Massachusetts General Hospital, uses multiple coils around the patient's head to perform parallel imaging in three dimensions, accelerating image acquisition. This technique allows for faster scans, which are crucial for both diagnosis and monitoring the adverse effects of amyloid immunotherapy, such as ARIA (Amyloid-Related Imaging Abnormalities).
Comparable Image Quality
To assess the reliability of the faster imaging, the researchers recruited 90 patients undergoing diagnostic scanning. Each patient was scanned using both the standard and the new protocols during the same session. The patient group included individuals with Alzheimer’s disease (21%), other pathologies (38%), and no pathology (41%). Three neuroradiologists independently evaluated the scans in a blinded manner.
The radiologists found the fast and standard scans nearly indistinguishable across multiple measures, including the detection of medial temporal lobe atrophy, posterior cortical atrophy, microbleeds, and white-matter hyperintensities. The type of scan did not influence the likelihood of clearing Alzheimer’s patients for amyloid immunotherapy. Rosa-Grilo concluded that the variability introduced by using the fast scan was less than the variability between different raters assessing the same scans, indicating that fast scans are no worse than standard ones.
Impact on Clinical Practice
Clifford Jack of the Mayo Clinic noted the necessity of such advancements to accommodate the increasing number of patients undergoing Alzheimer’s treatment. Faster MRI exams will be essential to manage the growing demands on radiology departments.
Jonathan Schott of Queen Square Institute of Neurology, London, estimates that the new technology could reduce the time slots currently scheduled for diagnostic scans from 30 minutes to 15 minutes. This efficiency gain is particularly valuable given the challenges some patients face with the claustrophobia of the MRI machine or the need to remain still for extended periods.
Schott also highlighted that the rapid scanning allows for quick repetition of sequences if a patient moves during the procedure, ensuring better data capture. While the study did not specifically evaluate ARIA monitoring, the protocol includes FLAIR and gradient echo sequences, which are expected to be useful for ARIA detection. Rosa-Grilo is currently conducting further tests to confirm this.
