Should a whole body PET CT or a PET CT of the head and neck be ordered for a patient with a recent subclavian artery stent placement on prasugrel therapy?

From the Guidelines

For a patient with a recent subclavian artery stent placement on prasugrel therapy, a whole body PET CT is the preferred choice if a PET CT is deemed necessary, as it allows for the evaluation of the body from the top of the head to at least mid-thigh, preferably to below the knees, as recommended by the EULAR guidelines for imaging in large vessel vasculitis 1. The EULAR guidelines suggest that the position of the patient should be supine, with the arms down, and blood glucose levels should be preferred to be less than 7 mmol/L (126 mg/dL), with less than 10 mmol/L (180 mg/dL) being acceptable 1. However, it's crucial to note that PET CT scans are not typically indicated for routine follow-up care of vascular stents, and other imaging modalities like duplex ultrasound, CT angiography (CTA), or conventional angiography are more appropriate for monitoring stent patency. The patient should continue prasugrel therapy as prescribed, usually 10mg daily, for at least 6-12 months following stent placement, and regular clinical follow-up appointments are necessary to monitor for symptoms of restenosis or thrombosis. In the context of large vessel vasculitis, FDG-PET can be useful for evaluating the cranial arteries, and a whole body PET CT would be more comprehensive than a PET CT of the head and neck alone, considering the recommendations for imaging from the top of the head to at least mid-thigh 1. It's also important to consider the interval between FDG infusion and image acquisition, which should be at least 60 min, preferably 90–120 min, as per the EULAR guidelines 1. Ultimately, the decision to use a whole body PET CT or another imaging modality should be based on the individual clinical circumstances and the specific needs of the patient.

From the Research

PET CT Scan Options

When considering a PET CT scan for a patient with a recent subclavian artery stent placement on prasugrel therapy, there are two main options: a whole body PET CT or a PET CT of the head and neck.

• The patient's recent subclavian artery stent placement may indicate a need to monitor for large vessel vasculitis (LVV), which can be detected using 18F-FDG PET/CT scans 2, 3, 4, 5, 6.
• A whole body PET CT scan may be more comprehensive in detecting LVV, as it can identify large vessel wall inflammation in various parts of the body, not just the head and neck 2, 5.
• On the other hand, a PET CT of the head and neck may be more focused on detecting inflammation in the subclavian artery and surrounding areas, which could be relevant given the patient's recent stent placement.

Considerations for PET CT Scans

When deciding between a whole body PET CT and a PET CT of the head and neck, consider the following:

• The sensitivity and specificity of 18F-FDG PET/CT scans in detecting LVV, which can range from 77% to 92% and 89% to 100%, respectively 6.
• The potential for false positive results, particularly in elderly patients with atherosclerotic vessels 6.
• The ability of PET/CT scans to monitor response to therapy and detect persistent activity, which can indicate non-responders to therapy 4, 6.

Disease Activity Assessment

PET/CT scans can also be used to assess disease activity in patients with LVV, with 18 FDG vascular uptake showing moderate correlation with clinical indices, laboratory markers, and signs of arterial involvement at morphological imaging 4.

• However, the role of PET/CT in evaluating disease activity is less clear-cut, and a comprehensive assessment, including clinical, laboratory, and morphological imaging, is still required to monitor patients with LVV over time 4.