Elsevier

Clinical Imaging

Volume 31, Issue 4, July–August 2007, Pages 253-258
Clinical Imaging

Original article
Benefit of CT venography for the diagnosis of thromboembolic disease

https://doi.org/10.1016/j.clinimag.2007.02.027Get rights and content

Abstract

Objective

The aim of this study was to determine the benefit of lower extremity CT venography (CTV) with pulmonary CT angiography (CTA) for diagnosing thromboembolic (TE) disease.

Subjects and Methods

Reports of all CTAs and CTVs over a 3-year interval (Group I) and CTAs, CTVs, and lower extremity Doppler ultrasounds (US) over a 1 1/2-year subset (Group II) were reviewed. Patient population was inpatients and emergency department patients who were assessed for pulmonary embolism (PE) and deep venous thrombosis (DVT) at a tertiary care hospital. Reported results for CTA or CTV were categorized as positive (CTAP, CTVP), negative (CTAN, CTVN), or indeterminate for PE or DVT. When CTV and US results were discrepant, medical records were reviewed for clinical management. Additional benefit of CTV was assessed by chi-square analysis.

Results

In Group I, 737 (81.1%) of 909 CTAs from combined CTA/CTV studies were negative. The diagnosis rate of TE disease increased from 13.0% to 17.3% with the addition of CTVPs (P=.01). Of the 119 cases in Group II undergoing combined CTA, CTV, and US, CTV and US were both positive in eight and both negative in 88. Of the seven discordant CTVs and USs with clinical follow-up, five CTVs were positive while USs were negative, three of which were treated clinically for TE disease, while two were considered falsely positive. As CTA also proved positive in one of the three, CTV therefore affected management in two of these five cases and increased the rate of thromboembolism diagnosis from 21.0% to 22.6%; however, this was not significant (P>.05). Two CTVNs were managed as false negatives.

Conclusions

The combined use of CTA and CTV significantly increases the rate of TE disease over CTA alone. In cases in which ultrasound is performed, however, there is no significant advantage to performing combined CTA/CTV studies.

Introduction

Deep venous thrombosis (DVT) is a risk factor for pulmonary embolism (PE). Both are treatable conditions that often remain undiagnosed because of their nonspecific signs and symptoms, resulting in significant morbidity and mortality. As the two entities are considered to be part of the same pathologic process [1], assessment for thromboembolic (TE) disease frequently entails investigation of both the pulmonary arterial system as well as the lower extremity deep venous system.

DVT is most often evaluated using either venous sonography or, more recently, computer-assisted tomography (CT) venography (CTV) [2], [3], [4], [5], [7], [8], [9], [10], [11]. CTV provides the additional ability to image DVT in pelvic veins as well as the lower extremity venous system immediately following CT angiography (CTA) of the pulmonary arterial system. Such a technique may provide diagnostic benefit over ultrasound (US) assessment in addition to expediting patient evaluation. As reported by Cham et al. in a large cohort of patients, CTV performed with contiguous, helically acquired, 10-mm sections, resulting in a 20% increase in the diagnosis of TE disease detection, compared with CTA alone [13]. Recently, the Prospective Investigation of Pulmonary Embolism Diagnosis II (PIOPED II) trial reported that the sensitivity of CTA for the diagnosis of pulmonary embolism was 83%, which increased to 90% with CTV in addition to CTA [14]. However, there are conflicting results regarding the role of CTV in the literature, given the option to perform ultrasound of the lower extremities instead of CTV and a concern of increasing radiation exposure to the pelvis [2], [3], [4], [15], [16]. Some reports conclude that CTV is a relatively accurate method for the diagnosis of DVT, compared with US [3], [7], [17], while others recommend that any isolated positive finding on CTV for DVT be confirmed with sonography [4].

Our objective was to assess the benefit of performing CTV with CTA for diagnosing TE disease in an acute tertiary care setting, with the specific intention of also identifying any advantage of combined CTA/CTV, as compared to CTA and duplex ultrasonography of the lower extremities.

Section snippets

Materials and methods

We reviewed reports in our radiology information system for all inpatients or patients who presented to the emergency department at one of the tertiary care hospitals at our medical center and were assessed by CTA and CTV between January 1, 2001, and November 30, 2003 (Group I). In addition, to assess the role of CTV in altering management in patients undergoing CTA and US, we searched the radiology information and noninvasive vascular laboratory databases for all patients who were referred for

Group 1: CTAs and CTVs performed concurrently during a 3-year period

Over a 3-year interval (Period I), 1716 CTAs were performed on 1618 patients (662 male, 956 female; mean, 57.7 years). There were 229 CTAPs (13.3%), 103 CTAIs (6.0%), and 1384 CTANs (80.6%).

Of the same 1716 studies, 909 CTVs were performed concurrently in 858 patients (360 male, 498 female; mean age, 59 years). There was no significant difference in terms of gender between the subset who had CTA/CTV and the 760 patients studied with CTA alone (chi-square=3.84, degrees of freedom (df)=l, P>.05).

Discussion

In our study, we demonstrated during a 3-year interval that 11.9% of our CTV studies were positive for DVT. This rate is slightly higher than, although not dissimilar to, some previous reports of large series. As reported by Cham et al. [18], for example, CTVs were positive in 8% in their 541 patients. Walsh and Redmond [8] reported 10.4% of their CTVs as positive involving 106 patients. Richman et al. [19] in 800 patients reported CTVs to be positive in 7%, and in a subsequent study of Cham et

Acknowledgments

The authors would like to thank Nanda Kirpekar of information technology in the department of Radiology at New York University for his assistance with database search. Amado Ross Sussman, M.D., is acknowledged for his assistance in data analysis.

References (21)

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