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Concept of an upright wearable positron emission tomography imager in humans

View Article: PubMed Central - PubMed

ABSTRACT

Background: Positron Emission Tomography (PET) is traditionally used to image patients in restrictive positions, with few devices allowing for upright, brain‐dedicated imaging. Our team has explored the concept of wearable PET imagers which could provide functional brain imaging of freely moving subjects. To test feasibility and determine future considerations for development, we built a rudimentary proof‐of‐concept prototype (Helmet_PET) and conducted tests in phantoms and four human volunteers.

Methods: Twelve Silicon Photomultiplier‐based detectors were assembled in a ring with exterior weight support and an interior mechanism that could be adjustably fitted to the head. We conducted brain phantom tests as well as scanned four patients scheduled for diagnostic F18‐FDG PET/CT imaging. For human subjects the imager was angled such that field of view included basal ganglia and visual cortex to test for typical resting‐state pattern. Imaging in two subjects was performed ~4 hr after PET/CT imaging to simulate lower injected F18‐FDG dose by taking advantage of the natural radioactive decay of the tracer (F18 half‐life of 110 min), with an estimated imaging dosage of 25% of the standard.

Results: We found that imaging with a simple lightweight ring of detectors was feasible using a fraction of the standard radioligand dose. Activity levels in the human participants were quantitatively similar to standard PET in a set of anatomical ROIs. Typical resting‐state brain pattern activation was demonstrated even in a 1 min scan of active head rotation.

Conclusion: To our knowledge, this is the first demonstration of imaging a human subject with a novel wearable PET imager that moves with robust head movements. We discuss potential research and clinical applications that will drive the design of a fully functional device. Designs will need to consider trade‐offs between a low weight device with high mobility and a heavier device with greater sensitivity and larger field of view.

No MeSH data available.


(Left) Toward the concept of a fully ambulatory imager within the laboratory environment; example: a running subject on a treadmill. Ultimately, this type of imager is what we hope is achieved. (Center Frames) Helmet_PET mounted on the head of a seated researcher and demonstrating freedom of rotational head movement by wide angles (J.B‐L.). This pilot imager was built to demonstrate the feasibility of a wearable PET imager (like the one illustrated on the left) using a single ring of detectors. (Right) Close up view of Helmet_PET showing the wearable and comfortable nature of this prototype (demonstrated by PM)
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brb3530-fig-0002: (Left) Toward the concept of a fully ambulatory imager within the laboratory environment; example: a running subject on a treadmill. Ultimately, this type of imager is what we hope is achieved. (Center Frames) Helmet_PET mounted on the head of a seated researcher and demonstrating freedom of rotational head movement by wide angles (J.B‐L.). This pilot imager was built to demonstrate the feasibility of a wearable PET imager (like the one illustrated on the left) using a single ring of detectors. (Right) Close up view of Helmet_PET showing the wearable and comfortable nature of this prototype (demonstrated by PM)

Mentions: The ring of 12 detector modules suspended from above using a flexible mechanical mount with an overhead cable and rotating pulley system (Figs 2, S1). The ring could be adjusted vertically on the subject's head to image the desired section of the human brain (a fully developed model with more detectors would cover the whole brain). We were able to attach the imager to the patient's head using the adjustable plastic frame and a chin strap from a standard safety helmet. Helmet_PET is currently about 3 kg in weight, and this weight was supported by the overhead flexible cable and not perceived by the patient, allowing for limited movement.


Concept of an upright wearable positron emission tomography imager in humans
(Left) Toward the concept of a fully ambulatory imager within the laboratory environment; example: a running subject on a treadmill. Ultimately, this type of imager is what we hope is achieved. (Center Frames) Helmet_PET mounted on the head of a seated researcher and demonstrating freedom of rotational head movement by wide angles (J.B‐L.). This pilot imager was built to demonstrate the feasibility of a wearable PET imager (like the one illustrated on the left) using a single ring of detectors. (Right) Close up view of Helmet_PET showing the wearable and comfortable nature of this prototype (demonstrated by PM)
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5036439&req=5

brb3530-fig-0002: (Left) Toward the concept of a fully ambulatory imager within the laboratory environment; example: a running subject on a treadmill. Ultimately, this type of imager is what we hope is achieved. (Center Frames) Helmet_PET mounted on the head of a seated researcher and demonstrating freedom of rotational head movement by wide angles (J.B‐L.). This pilot imager was built to demonstrate the feasibility of a wearable PET imager (like the one illustrated on the left) using a single ring of detectors. (Right) Close up view of Helmet_PET showing the wearable and comfortable nature of this prototype (demonstrated by PM)
Mentions: The ring of 12 detector modules suspended from above using a flexible mechanical mount with an overhead cable and rotating pulley system (Figs 2, S1). The ring could be adjusted vertically on the subject's head to image the desired section of the human brain (a fully developed model with more detectors would cover the whole brain). We were able to attach the imager to the patient's head using the adjustable plastic frame and a chin strap from a standard safety helmet. Helmet_PET is currently about 3 kg in weight, and this weight was supported by the overhead flexible cable and not perceived by the patient, allowing for limited movement.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Positron Emission Tomography (PET) is traditionally used to image patients in restrictive positions, with few devices allowing for upright, brain‐dedicated imaging. Our team has explored the concept of wearable PET imagers which could provide functional brain imaging of freely moving subjects. To test feasibility and determine future considerations for development, we built a rudimentary proof‐of‐concept prototype (Helmet_PET) and conducted tests in phantoms and four human volunteers.

Methods: Twelve Silicon Photomultiplier‐based detectors were assembled in a ring with exterior weight support and an interior mechanism that could be adjustably fitted to the head. We conducted brain phantom tests as well as scanned four patients scheduled for diagnostic F18‐FDG PET/CT imaging. For human subjects the imager was angled such that field of view included basal ganglia and visual cortex to test for typical resting‐state pattern. Imaging in two subjects was performed ~4 hr after PET/CT imaging to simulate lower injected F18‐FDG dose by taking advantage of the natural radioactive decay of the tracer (F18 half‐life of 110 min), with an estimated imaging dosage of 25% of the standard.

Results: We found that imaging with a simple lightweight ring of detectors was feasible using a fraction of the standard radioligand dose. Activity levels in the human participants were quantitatively similar to standard PET in a set of anatomical ROIs. Typical resting‐state brain pattern activation was demonstrated even in a 1 min scan of active head rotation.

Conclusion: To our knowledge, this is the first demonstration of imaging a human subject with a novel wearable PET imager that moves with robust head movements. We discuss potential research and clinical applications that will drive the design of a fully functional device. Designs will need to consider trade‐offs between a low weight device with high mobility and a heavier device with greater sensitivity and larger field of view.

No MeSH data available.