All PET detectors require cabling to supply power and transmit data, whether in analog or digital form. In this work we examine using High-Definition Multimedia Interface (HDMI®) cables as a single cable solution to both supply power and transmit analog signals for a SiPM based PET detector that will be used in a hybrid PET/MRI imaging system. HDMI cables are designed for digital audio/video transmission, with each cable having four pairs of shielded 100 ohm differential signal lines, each rated for 3.4 Gbit/s, along with 7 additional signal lines and a braided shield around the entire cable. While designed as a digital signal cable, the lines are rated for 40V DC and 0.5A current. To test using HDMI® cables for application in PET, a silicon photomultiplier (SiPM) PET detector module with a single HDMI® Type C ('mini) receptacle was built using a SensL SPMArray4 coupled to a dual-layer offset LYSO crystal array 1.67 mm crystal pitch. The 16 detector outputs were multiplexed to four signals using a simple resistor charge division network and driven using Analog Devices AD8132 op-amps. Detector bias of 30.2V and +/− 5V power for the op-amps was supplied through a 25′ length HDMI® cable connected through a custom receiver card. The signals were processed using NIM electronics and digitized with a PC based analog to digital converter (ADC) card. The PET detector had an average energy resolution of 14.3% full-width at half-maximum (FWHM) and an average timing resolution of 2.50 ns. The performance of the PET detector was unaffected when operated inside a 7T MRI system. The MR images showed degradation in signal to noise ratio (SNR) of between 7 and 23%, which is believe to be due to coupling between the RF coil and the PET detector shielding. The results of this work suggest that HDMI® cables with the Type C connector are a viable, cost effective and robust single cable solution for both analog signal and power/bias transmission for an MRI compatible PET insert system.
