PET holds promise for carotid plaque assessments
Positron emission tomography (PET) nuclear imaging has seen rapid growth in cardiology and oncology due to its improved accuracy over SPECT and its ability to expand into new areas of cardiovascular imaging. A new review in Stroke examines another possible use of PET: assessing carotid artery atherosclerosis for stroke prevention.[1]
"PET imaging of carotid plaques can accurately characterize pathophysiological processes and may be harnessed to develop our understanding of plaque physiology and evaluate the impact of novel therapeutic agents in modifying plaque characteristic. For clinical practice, carotid PET has potential future applications in improving recognition of symptomatic plaques, and personalized risk-stratification in stroke," the authors wrote.
They outlined the principles of carotid PET imaging and detailed how it could be implemented for clinical evaluations and in drug studies, since PET/CT can offer both anatomical and physiological assessments of plaque. Up to 37% of all ischemic strokes are related to large artery atherosclerosis, generally in the carotids, and this is also associated with early stroke recurrence. Monitoring this atherosclerosis via imaging can be useful. PET plaque pathophysiology assessments can show key processes of inflammation and microcalcifications.
The authors also think PET is well-suited for use in clinical trials because of its ability to offer detailed assessments of changes in plaque. They suggested that PET-based endpoints for early phase studies may improve research efficiency by enabling earlier rejection of candidate medications with limited changes with serial PET, and enabling successful agents to move more rapidly to phase III studies. PET may also be used to show the efficacy of targeted drugs binding with plaques by using radiolabeling of the drug.
PET may have value in translational research using surrogate imaging endpoints to show efficacy of therapeutic agents visually over shorter timescales. The authors also said PET's high sensitivity and inter-reader reliability makes it ideal for early phase trials, allowing for small sample sizes and shorter follow-up.
However, the authors also outlined some limitations of PET, including technical factors, issues with integrating the modality into workflows and standardizing outputs.
"Plaque imaging may be susceptible to artifact due to spillover and partial volume effects, and may also be affected by attenuation artifact (and artifact in the co-registered image) due to metallic implants. Movement between acquisition of attenuation maps and PET data may decrease accuracy of attenuation correction and anatomic co-registration, hindering interpretation," the authors wrote.
Logistical concerns of having the patient, radiotracer and scanner all available at specific times would need to be worked out. There is also a need for protocols to be standardized for imaging acquisition and interpretation.
Dave Fornell has covered healthcare for more than 17 years, with a focus in cardiology and radiology. Fornell is a 5-time winner of a Jesse H. Neal Award, the most prestigious editorial honors in the field of specialized journalism. The wins included best technical content, best use of social media and best COVID-19 coverage. Fornell was also a three-time Neal finalist for best range of work by a single author. He produces more than 100 editorial videos each year, most of them interviews with key opinion leaders in medicine. He also writes technical articles, covers key trends, conducts video hospital site visits, and is very involved with social media. E-mail: [email protected]