Prognostic significance of multidetector computed tomography in normotensive patients with pulmonary embolism: Rationale, methodology and reproducibility for the PROTECT study

The PROTECT study is designed to assess the prognostic significance of multidetector computed tomography (MDCT) findings in normotensive outpatients with pulmonary embolism (PE). MDCT assesses right ventricular dysfunction (RVD) by measuring the ratio of the rightto- left ventricular short axis diameters. The study uses 30-day all-cause mortality as the primary outcome. The study determined inter- and intraobserver reproducibility of CT findings of RVD. According to the local radiologists' measurements, 44 % of patients (42/96) showed RVD (defined as a ratio of the RV to the LV short axis greater than 0.9). The intraclass correlation was good (0.773, CI 95 %, 0.678-0.842). For interobserver reproducibility, the weighted kappa measurement was 0.730. Intraobserver reproducibility was very good (0.932, 95 % CI, 0.880- 0.962). The PROTECT study is designed to show the prognostic significance of MDCT for PE. Inter- and intraobserver agreement of interpretation of RVD were good.