Riccardo Iannaccone MD, Presenter: Nothing to Disclose

Carlo Catalano MD, Abstract Co-Author: Nothing to Disclose

Daniele Marin MD, Abstract Co-Author: Nothing to Disclose

Gianmaria De Filippis, Abstract Co-Author: Nothing to Disclose

Michele Di Martino, Abstract Co-Author: Nothing to Disclose

Roberto Passariello MD, Abstract Co-Author: Nothing to Disclose

To evaluate the diagnostic impact of different section thicknesses using 64-slice CT to detect hepatic colorectal metastases.

43 hepatic resection candidates with known colorectal metastases were prospectively examined. All patients underwent multiphasic CT performed with a 64-slice scanner (Sensation 64, Siemens). CT imaging parameters were: collimation 0.6 x 64 mm, pitch, 1.4; effective mAs, 160, and kVp, 120. All patients received nonionic contrast medium (400 mgI/mL; Iomeron 400, Bracco) at a rate of 5 mL/sec. A triple-phase CT protocol was performed with acquisition of hepatic arterial (delay time determined with bolus tracking technique), portal-venous (60 sec), and delayed (180 sec) phases. CT datasets were reconstructed with four different section thicknesses: 0.6 mm; 1 mm; 3 mm; and 5 mm. Each dataset was interpreted separately by three observers using a commercially available software (Vitrea 2, Vital Images). Four reading sessions were achieved with a time interval of 4 weeks. Sensitivity, positive predictive value (PPV), and area under the receiver operating characteristic curve (A(z)) were calculated. CT findings were correlated with surgery, intraoperative ultrasonography, and histopathologic studies in 28 patients and with consensus imaging follow-up in 15 patients.

The mean sensitivity and PPV for detection of hepatic colorectal metastases were 79% and 77% on 0.6-mm images, 78% and 77% on 1-mm images, 74% and 78% on 3-mm images, and 72% and 80% on 5-mm images, respectively. No significant difference in sensitivity and PPV among the images was detected. The mean A(z) values were 0.79, 0.78, 0.77, and 0.75 for 0.6-, 1-, 3-, and 5-mm images, respectively (no significant difference). However, with regard to small (1 cm in diameter or smaller) hepatic colorectal metastases, the mean sensitivities of 0.6- (72%) and 1-mm (71%) images was statistically significantly superior to those of 3- (63%) and 5-mm (60%) images (p < 0.05).

When using 64-slice CT, section thickness should be reduced to 0.6 or 1 mm to maximize identification of small (1 cm in diameter or smaller) hepatic colorectal metastases.

Iannaccone, R, Catalano, C, Marin, D, De Filippis, G, Di Martino, M, Passariello, R, Detection of Hepatic Colorectal Metastases: Diagnostic Impact of Different Section Thicknesses Using 64-slice CT.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4417207.html