Fractures of the thoracic spine in patients with minor trauma: Comparison of diagnostic accuracy and dose of biplane radiography and MDCT

Abstract

Objectives

To investigate the accuracy of biplane radiography in the detection of fractures of the thoracic spine in patients with minor trauma using multidetector computed tomography (MDCT) as the reference and to compare the dose of both techniques.

Methods

107 consecutive trauma patients with suspected fractures of the thoracic spine on physical examination were included. All had undergone biplane radiography first, followed by a MDCT scan between October 2008 and October 2012. A fourfold table was used for the classification of the screening test results. Both the Chi-square test (χ²) and the mean dose-length product (DLP) were used to compare the diagnostic methods.

Results

MDCT revealed 77 fractures in 65/107 patients (60.7%). Biplane radiography was true positive in 32/107 patients (29.9%), false positive in 19/107 patients (17.8%), true negative in 23/107 (21.5%) and false negative in 33/107 patients (30.8%), showing a sensitivity of 49.2%, a specificity of 54.7%, a positive predictive value (PPV) of 62.7%, a negative predictive value (NPV) of 41.1%, and an accuracy of 51.4%. The presence of a fracture on biplane radiography was highly statistical significant, if this was simultaneously proven by MDCT (χ² = 7.6; p = 0.01). None of the fractures missed on biplane radiography was unstable. The mean DLP on biplane radiography was 14.5 mGy cm (range 1.9–97.8) and on MDCT 374.6 mGy cm (range 80.2–871).

Conclusions

The sensitivity and the specificity of biplane radiography in the diagnosis of fractures of the thoracic spine in patients with minor trauma are low. Considering the wide availability of MDCT that is usually necessary for taking significant therapeutic steps, the indication for biplane radiography should be very restrictive.

Introduction

The immediate detection of traumatic fractures of the thoracic spine is important for further therapy and clinical outcome. Distribution is most common at the thoracolumbar junction with 4000 traumatic fractures each year in the US [1], [2]. The screening criteria for fractures of the thoracic spine among trauma centers are a controversial issue. Current recommendations are that there is no need to acquire biplane radiographs if major trauma patients undergo a MDCT (multidetector computed tomography) scan. MDCT is superior to biplane radiography and much faster [3], [4], [5], [6], [7], provides a sensitivity and a specificity of nearly 100% [3], detects even the tiniest fractures revealing potentially unstable lesions [8], and the patient has to be tabled only once. MDCT can often distinguish between acute and old fractures and other pathologies of the chest and the abdomen can be excluded.

But still the combination of biplane radiography (anteroposterior/lateral) and physical examination [3], [9], [10], [11] is widely used in the detection of fractures of the thoracic spine especially in minor trauma patients. While the mean dose of biplane radiography is lower than MDCT, the diagnostic quality of the radiographs is limited due to overlying arms and ribs especially in obese patients, showing a sensitivity and a specificity of 60–90% [3], [11]. Moreover, the reposition of the anguished patient is done twice on the table bucky.

In a recent study 222 patients with suspected fractures of the thoracic spine on physical examination were evaluated with both biplane radiography and MDCT [3]. 36/222 patients (17%) were found to have fractures, which were all detected by MDCT. The accuracy of biplane radiography was 87% using MDCT as the reference.

The purpose of our study was to investigate the accuracy of biplane radiography in the detection of fractures of the thoracic spine in patients with minor trauma using MDCT as the reference and to compare the dose of both techniques.