Combining PET and MRI data may be key to differentiating new type of dementia
New research highlights the potential for a PET- and MRI-based imaging approach for differentiating a new type of dementia from Alzheimer’s disease.
Limbic-predominant age-related TDP-43 encephalopathy, also known as LATE, was recently recognized as a type of dementia that occurs in older adults, typically presenting as memory-related cognitive decline. Due to its impact on memory, it is often mistaken for AD.
However, both LATE and Alzheimer's present differently on imaging. While AD is identified due to the accumulation of amyloid and tau proteins on the brain, LATE involves clumps of the protein TDP-43 in the limbic system. It is important to differentiate between the two due to the differing treatment methods for each.
A new paper in the Journal of Nuclear Medicine describes how combining PET and MRI imaging data can help distinguish between the two in living patients.
“The distinction in the causes of these types of dementia is critical, especially in the era of anti-amyloid therapies,” Satoshi Minoshima, MD, PhD, professor of radiology and imaging sciences at the University of Utah, Salt Lake City, said in a news release. “Because LATE has a different underlying pathology and a seemingly different prognosis, it cannot be diagnosed or treated in the same way as Alzheimer’s disease.”
LATE currently has no clinical biomarker to help identify it. As such, physicians have turned to imaging to determine whether specific neurological signatures can help diagnose the condition. For this latest research, experts developed stereotactic surface projection (3D-SSP) PET templates from autopsy-confirmed imaging datasets of patients with LATE and Alzheimer’s neuropathologic changes. Using this data, Z score maps were created to generate Z score product indices for 944 different 18F-FDG PET cases that were referred from cognitive disorder clinics. Patients were grouped into probable LATE, probable LATE and Alzheimer’s disease or probable Alzheimer’s disease groups, with MRI volumetry data guiding comparisons between each cohort.
MRI data suggest that pure LATE cases most often impact the medial temporal lobe, while the orbitofrontal gyrus and lateral temporal lobe are more often implicated in mixed LATE and AD cases. The two did not occur independently, the group noted; typically the same hemisphere was involved in both LATE and AD cases, likely due to their similar pathogenic synergy.
“The imaging patterns identified on PET and MRI in this study provide clinicians with a practical tool to detect potential LATE pathology in patients with cognitive impairment and to inform clinical management and future investigations of LATE,” noted Minoshima. “These efforts will ultimately advance precision diagnostics and treatment stratification in molecular imaging and nuclear medicine.”
Read the full study here.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.