Axel Van Der Gucht, Presenter: Nothing to Disclose

Benjamin Serrano, Abstract Co-Author: Nothing to Disclose

Florent Hugonnet, Abstract Co-Author: Nothing to Disclose

Benoit Paulmier, Abstract Co-Author: Nothing to Disclose

Nicolas Garnier, Abstract Co-Author: Nothing to Disclose

Marc Faraggi, Abstract Co-Author: Consultant, Siemens AG

PET acquisition requires several minutes which can lead to respiratory motion blurring, partial volume effect and SUV under-estimation. To avoid these artifacts, conventional 10-minute Phase-Based Respiratory Gating (PBRG) can be performed but is time-consuming and difficult with a non-compliant patient. HD-Chest is an amplitude-based gating method which keeps 35% of the counts at the end of expiration to minimize respiratory motion. We estimated the impact of HD-Chest on subdiaphramagtic lesion detectability and quantification.

Our study consisted of 30 patients for a total of 76 hepatic and 26 perihepatic lesions. Each patient underwent 3 acquisitions on a Siemens Biograph mCT (4 rings and time-of-flight): a Standard free breathing Whole Body (SWB, 5 to 7 steps / 2.5 min per step, 3.3 ± 0.4 MBq/Kq of 18F-FDG), a 10-min PBRG with six bins and a 5-min HD-Chest. All gated acquisitions were performed with an ANZAI respiratory gating system. SUVmax and Target to Background Ratio (TBR, expressed as SUVmax of lesions / SUVmean in healthy liver) were compared.

All 93 lesions in SWB images were detected in the gated images. PBRG and HD-Chest respectively revealed 5 and 9 new lesions and relocated 7 and 8 lesions. Localization remained uncertain for 2 lesions in both gated methods. Four lesions revealed by HD-Chest were missed by PBRG in 3 non-compliant patients. Compared to SWB, TBR but not SUVmax increased significantly with PBRG (respectively 40 ± 62%, p<0.05 and 10 ± 43%, p = 0.4) and with HD-Chest (respectively 70 ± 79%, p<0.05 and 23 ± 48%, p = 0.16).

A better detection rate, a better coregistration, a higher contrast, a reduction of the acquisition time by up to 50% compared to PBRG make of HD-Chest the first choice respiratory-gated PET protocole in the evaluation of subdiaphragmatic lesions.

Compared to phase-based respiratory gating, HD-Chest enhances detectability, image quality and reduces acquisition time without compromising quantification in evaluation of subdiaphragmatic lesions.

Van Der Gucht, A, Serrano, B, Hugonnet, F, Paulmier, B, Garnier, N, Faraggi, M, Impact of a New Respiratory Amplitude-based Gating Technique (HD-Chest) in Evaluation of Subdiaphragmatic PET Lesions.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13012180.html