Abstract:
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Purpose: To compare the diagnostic accuracy and interobserver agreement between 1.25 mm and 2.5 mm slice width contrast-enhanced CT scans in patients with suspected acute PE.
Methods and Materials: A repeated measures experimental design was performed in 114 patients with high clinical suspicion of acute PE. Each patient received a contrast-enhanced CT scan using 100-150 ml of non-ionic contrast media injected at 3-4 ml per second. Scans were acquired on an 8 slice CT scanner during suspended inspiration using 1.25-mm detector aperture, pitch 12, 120 kVp, 380 mA, 0.6 sec scan time. Two image sets were reconstructed using contiguous 1.25 mm and 2.5 mm sections and the standard algorithm. Two chest radiologists independently reviewed the 1.25 and 2.5 mm image sets in random order using a workstation. They recorded the location of pulmonary emboli using standard nomenclature. Their results were compared to a clinical gold standard, the prospective clinical assessment of the scan reached by consensus of three chest radiologists. This group had access to both the 1.25 and 2.5 mm image sets. The interpretation of the 1.25 and 2.5 mm slice width scans was compared to the clinical gold standard using the McNemar statistic.
Results: The consensus interpretation diagnosed acute PE in 33 of 114 patients (28.9%). Pooling the results of the two independent observers for the 2.5 and 1.25 mm slice width yielded sensitivity 74%, 91% and specificity 99%, 98% respectively. Compared to the 2.5 mm scans, the 1.25 mm images showed a 65% decrease in the false negative rate (17 to 6), but a tripling of the false positive rate (1 to 3). A significant difference (p<0.05) was observed between 1.25 and 2.5 mm slice width (McNemar test). The interobserver agreement was higher for the 1.25 mm (0.89) compared to the 2.5 mm (0.80) images (Kappa statistic).
Conclusion: The 1.25 mm section width significantly (p<0.05) improved diagnostic accuracy and showed higher interobserver agreement for acute PE.
(J. R. M. : General Electric Medical Systems, Grant (Self))
Questions about this event email: jmayo@vanhosp.bc.ca
Sheehan MD, R,
Comparison of 1.25 mm to 2.5 mm slice width in patients receiving contrast-enhanced CT for acute pulmonary embolism (PE). Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3105711.html
