Silvana Faria MD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: Functional CT (fCT) parameters, including blood flow (BF), blood volume (BV), mean transit time (MT) and permeability surface area product (PS), have the potential to improve our understanding of tumor biology and of the effects of oncologic treatments, in particular anti-angiogenic therapy. Reproducibility of measurements is an important prerequisite for its utility. The aim of our study was to assess the inter-observer variability of the measurement of fCT parameters, using commercially available CT perfusion software, in patients with liver metastases. Methods and Materials: Four observers independently measured the fCT parameters (BF, BV, MT, PS) from the raw CT cine data acquired from 30 CT perfusion studies. The studies were obtained from 15 patients with liver metastases receiving anti-angiogenic therapy in a variety of phase I clinical trials (7 renal cell carcinoma, 6 colon cancer, 1 gastriointestinal stromal tumor, 1 carcinoid tumor; 10 patients with followup studies). CT cine data was acquired utilizing a multislice scanner (4x5 mm axial slab, 1 second rotation, single 30 second breath-hold), and intravenous injection of non-ionic contrast media (40 mls, 7 ml/sec). The four observers independently prescribed ROIs for the aorta (as input function), and index liver lesions at a pre-defined axial level. Functional maps and fCT parameters were thus computed independently (Advantage Workstation, CT perfusion 3 software, GE Medical Systems). Inter-observer variability was assessed using Pearson correlation coefficients and the Wilks' statistic. Results: The independently calculated means (± standard deviations) of the CT perfusion parameters for the four observers were: blood flow 81.9 ± 73.3, 79.1 ± 68.0, 73.9 ± 66.0, 80.5 ± 71.1 ml/min/100gm tissue; blood volume 8.8 ± 5.6, 8.6 ± 5.3, 8.3 ± 5.5, 9.0 ± 5.6 ml/100gm; mean transit time 11.8 ± 4.0, 11.8 ± 4.0, 11.9 ± 4.1, 12.3 ± 4.1 seconds; permeability surface area product 18.3 ± 7.4, 18.8 ± 7.8, 18.0 ± 9.1, 19.1 ± 8.1 ml/min/100gm. There were highly significant correlations between individual observers for all measurements (p<0.0001), and no significant inter-observer variability was detected in any of the measured functional parameters (p=0.20, p=0.32, p=0.34, p=0.36, respectively). Conclusion: The measurement of functional CT parameters can be undertaken with high reproducibility, which supports its potential utility. (T.L. received a grant from GE Medical Systems.)       Questions about this event email: cng@mdanderson.org

Faria MD, S, Inter-Observer Variability in the Measurement of Functional CT Parameters in Patients with Hepatic Metastases.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3102994.html