Differences in gross tumor volumes for pancreatic cancer: a comparison of ungated positron emission tomography and contrast-enhanced four-dimensional computed tomography

• Published in: Japanese journal of radiology Vol. 37; no. 4; pp. 336 - 340
• Main Authors: Takahashi, Shigeo, Anada, Masahide, Kinoshita, Toshifumi, Nishide, Takamasa, Shibata, Toru
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.04.2019; Springer Nature B.V
• Subjects: Cancer; Computation; Computed tomography; Emission analysis; Imaging; Medical imaging; Medicine; Medicine & Public Health; Nuclear Medicine; Observers; Original Article; Pancreatic cancer; Positron emission; Positron emission tomography; Radiology; Radiotherapy; Tomography; Tumors; Contouring; Ungated; 3D-PET; 4D-CT; Delineation
• ISSN: 1867-1071; 1867-108X
• DOI: 10.1007/s11604-019-00812-8

Purpose We assessed differences in gross tumor volumes (GTVs) for pancreatic cancer between respiratory-ungated positron emission tomography (3D-PET) and contrast-enhanced four-dimensional computed tomography (CE-4DCT). Materials and methods We evaluated the GTVs in 21 patients. The sum of the GTVs, which was individually delineated by observers 1 and 2 on the CE-4DCT images from all respiratory phases, was used as GTV-4DCT. The GTVs on the 3D-PET images were extracted with three thresholds: 20%, 30%, and 40% of maximum activity concentration (GTV- n %). We selected one of the GTV- n %, which mostly resembled GTV-4DCT in size, as GTV-PET. Differences in the GTVs were analyzed. Results Median values of GTV-4DCT for observers 1, 2, and GTV-PET were 55.0 mL, 45.7 mL, and 14.6 mL, respectively. GTV-PET was smaller than GTV-4DCT for observers 1 and 2 ( p  < 0.01 each). Differences of median values of maximum diameters between GTV-4DCT and GTV-PET were 1.7–1.8 cm, 1.4–1.6 cm, and 1.9–2.1 cm in the left–right, anterior–posterior, and craniocaudal directions, respectively. Conclusion GTV-PET based on 3D-PET images was smaller than GTV-4DCT for pancreatic cancer. When we refer to 3D-PET images without CE-4DCT images, we need to pay attention to the above-mentioned finding to contour the GTV.