The effect of single-detector CT versus MDCT on clinical outcomes in patients with suspected acute pulmonary embolism and negative results on CT pulmonary angiography

AJR Am J Roentgenol. 2005 Apr;184(4):1231-5. doi: 10.2214/ajr.184.4.01841231.


Objective: We sought to compare the clinical outcomes of patients in whom pulmonary embolism (PE) has been ruled out with single-detector CT versus MDCT, given the improved visualization of subsegmental clots with the latter and the recent increase in use of CT for evaluation of PE.

Subjects and methods: Two cohorts of patients undergoing CT for suspected PE with either single-detector CT (3-mm collimation and pitch of 1.7) or MDCT (2-mm collimation and pitch of 1) scanners were prospectively observed and compared using predefined criteria for evidence of subsequent thromboembolic disease during the 6 months after the acquisition of their initial scan.

Results: Ninety-eight patients were scanned using a single-detector CT scanner. Of these, none had evidence of subsequent PE or deep venous thrombosis (DVT), and six (6.1%) died of unrelated causes. Of the 100 patients scanned using an MDCT scanner, one (1.0%) had a subsequent nonfatal PE 2 months after the initial scanning, one (1.0%) had DVT 1 month after the initial scanning, and eight (8.0%) died of unrelated causes. No significant difference was found in either the probability of subsequent thromboembolic events (chi(2) = 0.3183, degrees of freedom [df] = 1, p = 1) or frequency of unrelated deaths (chi(2) = 0.2655, df = 1, p = 0.7829) between patients scanned using single-detector CT or MDCT protocols.

Conclusion: Our results show that patients with suspected acute PE and negative CT results have acceptable clinical outcomes in the absence of anticoagulation treatment up to 6 months after acquisition of their initial scan. Furthermore, we found that the increased visualization of smaller, more peripheral arteries afforded by multislice technology did not affect clinical outcome.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Angiography
  • Anticoagulants / therapeutic use
  • Chi-Square Distribution
  • Contrast Media
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Imaging, Three-Dimensional
  • Iohexol
  • Male
  • Middle Aged
  • Prospective Studies
  • Pulmonary Embolism / diagnostic imaging*
  • Pulmonary Embolism / drug therapy
  • Tomography, X-Ray Computed / methods*
  • Treatment Outcome


  • Anticoagulants
  • Contrast Media
  • Iohexol