RT Journal Article SR Electronic T1 68Ga-DOTATOC PET/CT of Neuroendocrine Tumors: Spotlight on the CT Phases of a Triple-Phase Protocol JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 697 OP 704 DO 10.2967/jnumed.110.083741 VO 52 IS 5 A1 Juri Ruf A1 Jan Schiefer A1 Christian Furth A1 Ortud Kosiek A1 Siegfried Kropf A1 Friederike Heuck A1 Timm Denecke A1 Marianne Pavel A1 Andreas Pascher A1 Bertram Wiedenmann A1 Holger Amthauer YR 2011 UL http://jnm.snmjournals.org/content/52/5/697.abstract AB The diagnostic value of neuroendocrine tumor (NET) imaging using PET with integrated CT is dependent on both components. This retrospective study assessed the value of the single CT phases of a triple-phase (early arterial, portal-venous inflow, and venous) CT protocol in comparison to 68Ga-DOTATOC PET in a masked reading. Methods: 68Ga-DOTATOC PET/CT examinations from 51 patients with known or suspected NET were included. Two readers assessed the data of PET and each of the 3 CT phases for NET lesions independently (using a 3-point score: 1 = benign, 2 = indeterminate, and 3 = malignant) and by consensus (using binary benign/malignant interpretation only). Only lesions within the field of the abdominal scan were evaluated. Clinical and imaging follow-up, histopathology (if available), and the decision of an interdisciplinary truth-panel served as a standard of reference. In addition to the calculation of standard statistical parameters (including general linear mixed models), interobserver reliability was estimated (Cohen's κ). Results: Of 510 abdominal lesions observed, 354 were classified as malignant. Sensitivity was 77.1% for combined triple-phase CT, 53.4% for arterial CT, 66.1% for portal-venous CT, 66.9% for venous CT, and 72.8% for PET. The respective specificities were 85.3%, 92.9%, 92.3%, 89.7%, and 97.4%, and the respective accuracies were 79.6%, 65.5%, 74.1%, 73.9%, and 80.4%. Although arterial CT was found to be inferior to PET, portal-venous CT, and venous CT (P < 0.001), the differences between the other scans were not significant. Detection was exclusively by PET for 16.1% of lesions, by triple-phase CT for 20.3%, by arterial CT for 0.5%, by portal-venous CT for 3.9%, and by venous CT for 3.9%. Regarding interobserver reliability, the κ-value was 0.768 for PET, 0.391 for triple-phase CT, 0.577 for arterial CT, 0.583 for portal-venous CT, and 0.482 for venous CT. Conclusion: No CT phase can be omitted in NET imaging, and the triple-phase protocol continues to be strongly recommended also for PET/CT.