Influences of point-spread function and time-of-flight reconstructions on standardized uptake value of lymph node metastases in FDG-PET

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• 作者：Go Akamatsu ; Katsuhiko Mitsumoto ; Takafumi Taniguchi ; Yuji Tsutsui ; Shingo Baba ; Masayuki Sasaki
• 关键词：Standardized uptake value ; Lymph node metastasis ; Point-spread function ; Time-of-flight ; FDG-PET
• 刊名：European Journal of Radiology
• 出版年：January, 2014
• 年：2014
• 卷：83
• 期：1
• 页码：226-230
• 全文大小：628 K

文摘

Purpose

The purpose of this study was to investigate the effects of point-spread function (PSF) and time-of-flight (TOF) on the standardized uptake value (SUV) of lymph node metastasis in FDG-PET/CT.

Materials and methods

This study evaluated 41 lymph node metastases in 15 patients who had undergone ¹⁸F-FDG PET/CT. The lesion diameters were 2.5 cm or less. The mean short-axis diameter of the lymph nodes was 10.5 卤 3.7 mm (range 4.6-22.8 mm). The PET data were reconstructed with baseline OSEM algorithm, with OSEM + PSF, with OSEM + TOF and with OSEM + PSF + TOF. A semi-quantitative analysis was performed using the maximum and mean SUV of lymph node metastases (SUV_max and SUV_mean) and mean SUV of normal lung tissue (SUV_lung). We also evaluated image quality using the signal-to-noise ratio in the liver (SNR_liver).

Results

Both PSF and TOF increased the SUV of lymph node metastases. The combination of PSF and TOF increased the SUV_max by 43.3% and the SUV_mean by 31.6% compared with conventional OSEM. By contrast, the SUV_lung was not influenced by PSF and TOF. TOF significantly improved the SNR_liver.

Conclusion

PSF and TOF both increased the SUV of lymph node metastases. Although PSF and TOF are considered to improve small-lesion detectability, it is important to be aware that PSF and TOF influence the accuracy of quantitative measurements.