Suboptimal CT pulmonary angiography in the emergency department: a retrospective analysis of outcomes in a large academic medical center

Abstract

Optimal CT pulmonary angiography (CTPA) is a prerequisite for accurate diagnosis and management of suspected venous thromboembolic disease (VTE) in the emergency department (ED). However, a certain proportion of CTPA studies are diagnostically limited or non-diagnostic due to various technical causes. In this study, we analyze the incidence and cause of suboptimal CTPA studies in the ED and assess the need for additional imaging. Reports of 1444 consecutive CTPAs performed in an ED on adult patients over a 25-month period beginning November 30, 2011, were reviewed. The observed suboptimal CTPA rate was 4.2 % (60/1444). The most common causes of limited or non-diagnostic CTPA in the ED were related to timing of contrast bolus or IV infiltration (26/60, 43.4 %), respiratory motion (16/60, 26.7 %), multifactorial causes (10/60, 16.7 %), and patient motion (8/60, 13.3 %). Of the 60 studies included, only 7 patients (11.7 %) underwent additional diagnostic imaging during the same hospital visit for VTE, while 3 patients (5.0 %) underwent additional imaging for suspected VTE over the next 2 months. A total of 2/60 (3.4 %) patients had documented acute PE on additional imaging performed either on the same hospital visit or within 2 months. Regardless of the factors contributing to suboptimal CTPA, only a very small proportion of patients receive additional imaging to evaluate for VTE, either on the same visit or during the next 2 months (16.7 %, 10/60 patients). A small number (3.4 %) of these patients have documented acute PE within 2 months when additional imaging tests were performed.

Rethinking Intravenous Catheter Size and Location for Computed Tomography Pulmonary Angiography

“…We found a fairly high rate of suboptimal CTPA, 19.3%. This number is substantially higher than the 4% found in a study by Bates et al that used a similar definition of “suboptimal.”9 The chart review methods in that study were not as rigorous as ours, and we suspect the true suboptimal rate is higher than 4%.…”

“…However, impressions stating inability to exclude subsegmental PE were not included as suboptimal, since subsegmental PEs may not need to be treated 8. Note that our definition of “suboptimal” is consistent with prior literature on this topic 9…”

“…Our initial choice of a sample size of 1500 was based on the size of a previously published study about suboptimal CTPAs9 and gestalt that this would be sufficiently large. Since no prior study has evaluated the relationship between IV size or location and suboptimal CTPAs, we initially did not have sufficient information to perform a formal power calculation.…”

Acute pulmonary embolism multimodality imaging prior to endovascular therapy

“…Attenuation along a vessel may be disturbed by beam hardening artifacts from contrast originating from abutting vasculature, wires, or medical devices [33]. Studies have found 0.5% to 12.1% of CTPA studies to be non-diagnostic [78,[100][101][102][103][104][105][106][107][108][109][110][111][112].…”

Imaging of suspected pulmonary embolism and deep venous thrombosis in obese patients

“…Motion artifact is a major cause of indeterminate CTPA examinations when using a 4 to 16-slice scanner, but this has been improved with a 64-slice scanner, in some reports in the literature. 9,34,46 In patients who cannot do inspiratory breath holding, shallow free breathing can be effective and does not cause motion artifact, when using dualsource high-pitch CTPA. 47 Lowering the pitch by using thicker collimation can also decrease photon starvation, and thus improve SNR 2,25 (Figure 4).…”