American Journal of Neuroradiology 2009;30:1107.
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American Journal of Neuroradiology
DOI 10.3174/ajnr.A1540
HEAD & NECK
Intra- and Interobserver Agreement and Impact of Arterial Input Selection in Perfusion CT Measurements Performed in Squamous Cell Carcinoma of the Upper Aerodigestive Tract
From the Departments of Radiology (G.P., L.P., P.S., M.B.), Epidemiology and Biostatistics (S.R.), and Head and Neck Surgery (G.G., F.C.), European Institute of Oncology, Milan, Italy; and School of Medicine (G.D'A., M.B.), University of Milan, Milan, Italy.
Please address correspondence to Giuseppe Petralia, MD, Department of Radiology, European Institute of Oncology, 435 Via Ripamonti, 20141 Milan Italy; e-mail: giuseppe.petralia{at}ieo.it
BACKGROUND AND PURPOSE: CT Perfusion (CTP) has shown potential for assessing head and neck tumors. Our purposes were to assess the inter- and intraobserver agreement of CTP measurements and to investigate whether the selection of arterial input, ipsilateral versus contralateral to the tumor or left-versus-right external carotid artery (ECA), may affect CTP measurements in patients with squamous cell carcinoma (SCCA) of the upper aerodigestive tract.
MATERIALS AND METHODS: Twenty-six patients with SCCA were enrolled in this prospective study and underwent CTP. Data were analyzed by 2 expert readers and by an inexperienced reader for interobserver agreement and by the 2 expert readers for intraobserver agreement assessment, by using the ECA ipsilateral to tumor site as arterial input. All 3 readers repeated their analysis by using the ECA contralateral to tumor site as arterial input. Inter- and intraobserver agreement was assessed by using the Bland-Altman approach; CTP measurements by using ipsilateral-versus-contralateral or left-versus-right ECA were compared by using the Wilcoxon signed rank test.
RESULTS: The geometric mean of the ratios (95% limits of agreement) for inter- and intraobserver agreement ranged from 0.96 (0.75–1.23) to 1.00 (0.92–1.10) for blood flow (BF), from 0.88 (0.63–1.21) to 1.00 (0.88–1.14) for blood volume (BV), from 0.96 (0.64–1.44) to 0.98 (0.76–1.27) for mean transit time (MTT), and from 0.85 (0.41–1.76) to 1.14 (0.70–1.86) for permeability surface area product (PS). Significantly higher tumor PS and MTT for 2 readers and lower tumor BF for 1 of 3 readers were observed when the arterial input was placed in the left ECA.
CONCLUSIONS: BF, BV, and MTT demonstrated higher inter- and intraobserver agreement than PS. The selection of arterial input, right-versus-left ECA, may determine changes in CTP measurements in patients with SCCA of the upper aerodigestive tract.