Ultrasound wrist mapping to develop a noninvasive radiation detector for dynamic positron emission tomography

Quantitative PET studies require a measurement of the arterial input function (AIF), the time-dependent radiotracer concentration in arterial blood plasma. Several groups are developing non-invasive detectors to measure the AIF from the radial artery. This study quantifies the depth and cross-sectional area of the radial artery and accompanying veins at different wrist positions using ultrasound. These anatomical data will guide the design of a non-invasive, wrist-worn detector for AIF acquisition—a practical, patient-friendly alternative to invasive blood sampling. Ultrasound imaging of the wrist was performed on 154 healthy individuals at specified distances from the distal wrist crease (2 cm , 4 cm , and 6 cm ). The depths of the radial artery at distances of 2 cm , 4 cm , and 6 cm from the distal wrist crease are 3.36 (1.25) mm , 4.08 (1.81) mm , and 4.66 (2.23) mm , respectively (mean (SD)). Similarly, the cross-sectional areas of the radial artery at these distances are 4.23 (1.75) mm ² , 3.92 (1.71) mm ² , and 3.90 (1.88) mm ² , respectively. The radial artery becomes larger and more superficial near the wrist, suggesting a radiation detector be placed 2 cm from the distal wrist crease on the left arm, where it is generally more superficial than on the right.