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Impact of 18F-Choline PET scan acquisition time on delineation of GTV in prostate cancer [Poster Abstract]

Parkinson, Craig ORCID:, Chan, Joachim, Syndikus, Isabel, Marshall, Christopher ORCID:, Staffurth, John and Spezi, Emiliano ORCID: 2017. Impact of 18F-Choline PET scan acquisition time on delineation of GTV in prostate cancer [Poster Abstract]. Radiotherapy and Oncology 123 (S1) , S714-S715. 10.1016/S0167-8140(17)31768-1

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Background: Dose painting radiotherapy requires accurate outlining of primary tumour volumes in the prostate. T2-Weighted (T2W) Magnetic Resonance Imaging (MRI) is the best imaging method for defining the gross tumour volume (GTV). Choline positron emission tomography (PET) is currently a controversial tracer. The image acquisition differs significantly in published studies. Many used early static imaging. One study found that 18F-choline PET/CT with late image acquisition has superior accuracy to T2W MR and functional MR alone1. We investigate whether increasing 18F-Choline PET scan acquisition time from 60 (PET-60) to 90 (PET-90) minutes improves GTV TVD. Methods. Analysis was performed on 9 18F-Choline PET scans. Patients were injected with 370MBq of activity. Three clinicians (C1, C2 and C3) independently and without reference to each other contoured GTVs on each of the T2W-MRI, PET-60 and PET-90 scans at differing times. Scans were registered by a clinician using rigid co-registration. The treating clinicians MRI contour was used as a reference contour. The resulting PET and MRI GTVs were transferred to the PET-60 and PET-90 scans after image registration. The Dice Similarity Coefficient (DSC), Specificity (Sp) and Sensitivity (S) were calculated from contour mask voxel analysis. Results. Table 1 shows the mean and range DSC, S and Sp scores on MRI, PET-60 and PET-90 for C1, C2 and C3 in comparison to the treating clinicians contour on MRI (C1). A 2 sampled T-test (P < 0.01) showed, no significant difference in the Sp, S and DSC between GTVs on PET-60 and PET-90 scans. Further to this, as shown in Figure 1, variability in GTV delineation is significant between observers in a singular case as well as across imaging modalities. Conclusion. Compared to MRI delineated GTVs, 18F-Choline PET GTVs are significantly different. This study found however that increasing the PET scan acquisition time from 60 to 90 minutes did not improve the performance of GTV TVD in comparison to MRI delineated GTV.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Subjects: Q Science > Q Science (General)
Publisher: Elsevier
ISSN: 0167-8140
Funders: Velindre Cancer Centre, Engineering and Physical Sciences Research Council
Date of First Compliant Deposit: 14 December 2017
Last Modified: 04 May 2023 11:52

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