ABSTRACT
Pulmonary embolism (PEs) is a common and potentially fatal condition associated with signicant morbidity and mortality in untreated patients. Prompt and accurate diagnosis of PEs has been shown to greatly inuence patient outcome (Dalen and Alpert 1975; Price 1976). Computed tomographic pulmonary angiography (CTPA) has been reported to be an eective means for the clinical diagnosis of PEs (Remy-Jardin et al. 1992; Din et al. 1998; Rubin et al. 1998; McCollough and Zink 1999; Stein 1999; Ghaye 2001; Raptopoulos and Boiselle 2001; Schoepf et al. 2002a). CT has advantages over conventional pulmonary angiograms and ventilation/perfusion (V/Q) scan because of its direct imaging of the blood clot, better interobserver agreement, greater accuracy, and possibility to explain patient’s sign and symptoms (RemyJardin et al. 1992; Rubin et al. 1998; McCollough and Zink 1999; Stein et al. 2006). e main limitation of single-detector spiral CT has been the detection of small peripheral emboli (Goodman et al. 1995; Drucker et al. 1998; Perrier et al. 2001; Schoepf et al. 2004; Schoepf and Costello 2004) and the isolated subsegmental emboli (Stein 1999). e main reason for inadequate detection of PEs in these small vessels is partial
volume eects and cardiac and respiratory motions (Ghaye 2001). Although the clinical signicance of small PEs has not been established, small PEs may produce signicant morbidity in patients with underlying cardiorespiratory disease (Din et al. 1998) and may indicate a risk for the recurrence of more signicant emboli among stable patients. Studies (Hull et al. 1994; Oser et al. 1996; Patriquin et al. 1998) also indicated that the presence of peripheral PEs may be an indicator for current deep vein thrombosis, thus potentially heralding more severe embolic events. In addition, it is important to estimate the total burden of pulmonary vascular clots in patients with acute PEs to determine proper therapy and to improve patient outcome (Bankier et al. 1997; Qanadli et al. 2001; Wood et al. 2002; Mastora et al. 2003; Araoz et al. 2003; Wu et al. 2004). Figure 16.1 shows examples of PEs visualized on CTPA images.
