El-Ghussein Fadi, Jiang Shudong, Pogue Brian W, Paulsen Keith D
J Biomed Opt. 2014;19(7):070502. doi: 10.1117/1.JBO.19.7.070502.
Tissue spectroscopy inside the magnetic resonance imaging (MRI) system adds a significant value by measuring fast vascular hemoglobin responses or completing spectroscopic identification of diagnostically relevant molecules. Advances in this type of spectroscopy instrumentation have largely focused on fiber coupling into and out of the MRI; however, nonmagnetic detectors can now be placed inside the scanner with signal amplification performed remotely to the high field environment for optimized light detection. In this study, the two possible detector options, such as silicon photodiodes (PD) and silicon photomultipliers (SiPM), were systematically examined for dynamic range and wavelength performance. Results show that PDs offer 10⁸(160 dB) dynamic range with sensitivity down to 1 pW, whereas SiPMs have 10⁷(140 dB) dynamic range and sensitivity down to 10 pW. A second major difference is the spectral sensitivity of the two detectors. Here, wavelengths in the 940 nm range are efficiently captured by PDs (but not SiPMs), likely making them the superior choice for broadband spectroscopy guided by MRI.
磁共振成像（MRI）系统内的组织光谱学通过测量快速血管血红蛋白反应或完成诊断相关分子的光谱鉴定增加了显著价值。这种光谱仪器的进展主要集中在光纤与MRI的进出耦合；然而，现在非磁性探测器可以放置在扫描仪内部，信号放大在远离高场环境的地方进行，以优化光检测。在本研究中，系统地研究了两种可能的探测器选项，如硅光电二极管（PD）和硅光电倍增管（SiPM）的动态范围和波长性能。结果表明，PD具有10⁸（160 dB）的动态范围，灵敏度低至1 pW，而SiPM具有10⁷（140 dB）的动态范围，灵敏度低至10 pW。第二个主要区别是两种探测器的光谱灵敏度。在此，940 nm范围内的波长能被PD有效捕获（但SiPM不能），这可能使它们成为MRI引导的宽带光谱学的更佳选择。
