Accuracy of amplitude-based respiratory gating for PET/CT in irregular respirations
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ORIGINAL ARTICLE
Accuracy of amplitude-based respiratory gating for PET/CT in irregular respirations Yuji Tsutsui • Daisuke Kidera • Takafumi Taniguchi • Go Akamatsu • Isao Komiya • Yoshiyuki Umezu • Yoshiyuki Kitamura • Shingo Baba • Masayuki Sasaki
Received: 6 February 2014 / Accepted: 9 June 2014 Ó The Japanese Society of Nuclear Medicine 2014
Abstract Objective We evaluated the accuracy of amplitude gating PET (AG-PET) compared with phase gating PET (PGPET) in relation to respiratory motion patterns based on a phantom analysis. Method We used a NEMA IEC body phantom filled with an 18F solution with a 4:1 sphere-to-background radioactivity ratio (12.6 and 2.97 kBq/mL). PET/CT scans were acquired in a motionless and moving state on a Biograph mCT. The respiratory movements were simulated by four different waveform patterns consisting of ideal breathing, breathing with a pause period, breathing with a variable amplitude and breathing with a changing baseline. AG-PET selects the narrow bandwidth containing 20 % of the respiratory cycle. PG-PET was reconstructed with five gates. The image quality was physically assessed using the percent contrast (QH,10mm), background variability (N10mm) recovery coefficient (RC), and sphere volumes. Result In regular motion patterns with ideal breathing and breathing with a pause period, the QH,10mm, RC and sphere
volumes were not different between AG-PET and PG-PET. In the variable amplitude pattern, the QH,10mm of AG-PET was higher than that of PG-PET (35.8 vs 28.2 %), the RC of AG-PET was higher than that of PG-PET and sphere volume of AG-PET was smaller than that of PG-PET (6.4 vs 8.6 mL). In the changing baseline pattern, the QH,10mm of AG-PET was higher than that of PG-PET (42.4 vs 16.7 %), the RC of AG-PET was higher than that of PGPET and sphere volume of AG-PET was smaller than that of PG-PET (6.2 vs 9.8 mL). The N10mm did not differ between AG-PET and PG-PET, irrespective of the motion pattern. Conclusion Amplitude gating PET is considered to be more accurate than phase gating PET for examining unstable respiratory motion patterns, such as those involving a variable amplitude or changing baseline. Keywords Respiratory gating PET/CT Amplitude-based gating Phase-based gating
Introduction Y. Tsutsui I. Komiya Y. Umezu Division of Radiology, Department of Medical Technology, Kyushu University Hospital, Fukuoka, Japan e-mail: [email protected] D. Kidera T. Taniguchi G. Akamatsu M. Sasaki (&) Division of Radiological Science, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan e-mail: [email protected] Y. Kitamura S. Baba Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
PET/CT has been used to make the differential diagnosis, determine staging, evaluate the response to therapy and predict prognosis of lung cancer [1–5]. In particular, accurate imaging of lung cancer is required for radiothera
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