Concept of an upright wearable positron emission tomography imager in humans.

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 F(18-) 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 F(18-) FDG dose by taking advantage of the natural radioactive decay of the tracer (F(18) 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.

Non-invasive serial casting to treat idiopathic toe walking in an 18-month old child.

BACKGROUND: Idiopathic toe walking is characterized by persistent toe walking in the absence of clinically diagnosed neuromuscular disease. Treatment options in children diagnosed with idiopathic toe walking include: observation, physical therapy, serial casting, or Achilles tendon (heel cord) lengthening surgery. OBJECTIVE: In this case report, we present a non-invasive serial casting protocol to treat severe and persistent toe walking in an 18-month old child, diagnosed as an idiopathic toe walker following neurological examination. METHODS: A series of below knee casts was used to provide a consistent stretch to the plantar flexor muscles. Upon removal of each set of casts, passive range of motion at the ankles was measured with a goniometer. RESULTS: Four sets of casts, each lasting approximately one week, increased passive ankle dorsiflexion to 10° of neutral and established a heel-toe walking gait. Improvements in ankle range of motion and gait were maintained upon repeated examinations at 3, 7, and 12 months post-casting. CONCLUSIONS: These results demonstrate that non-invasive procedures, such as serial casting, can be successful in very young children diagnosed as idiopathic toe walkers. Early identification and intervention for this diagnosis may eliminate the need for invasive surgeries and associated risks in this population.