Corroboration of Spiral CT angiography with D-dimer Assays in the accurate diagnosis of Pulmonary Embolism with assessment of its Image quality
(i)To determine the prevalence of PE in a group of patients with clinical suspicion of PE & to evaluate the utility of CT pulmonary angiography using Spiral CT systems.
(ii) To assess the image quality of single source CT in diagnosis of PE.
(iii) Assessing the reliability of D-dimer Test in ruling out PE.
Materials and Methods:
(i) 50 patients clinically suspected of having PE were examined with contrast-enhanced spiral CT in the CT department of the 1st Affiliated hospital of Zhengzhou University from August 2014 to December 2015.
(ii) The 50 patients enrolled in the study who underwent spiral CT scan, were then assessed for the image quality, including analyzing the attenuation in the pulmonary trunk and its branches and comparing it with the background noise (SD). Using RIS/PACS workstation (Centricity 4.1, General Electric Healthcare, Darmstadt, Germany) using a circle tool. Mean attenuation values and standard deviation were recorded and displayed in Hounsfield Units (HU).
The CT values, SD values and Signal-Noise Ratio (SNR) obtained were then statistically analyzed using SPSS 17.0
(iii) D-dimer Test was done for all 50 patients and a reference range of 0 – 0.3 µg/l was considered as normal.
- Spiral CT was a valuable method for identifying 20 patients with PE (sensitivity, 100%). In 10 of the 20 patients devoid of PE, Spiral CT provided the alternate clinical diagnosis. In the remaining 10 patients, spiral CT scans were
- The statistical analysis of the CT values, SD (background noise) and SNR of the pulmonary trunk and pulmonary artery (without right or left predilection) showed a p-value > 0.05.
(iii) D-dimer Test showed elevated levels in 18 patients who were diagnosed PE on Spiral CT scans. In 8 patients without PE on Spiral CT scans also showed elevated D-dimer levels. The remaining 22 patients had normal D-dimer levels.
- Spiral CT has a good sensitivity and specificity for the diagnosis of PE. In the majority of patients who do not have PE, it also provides important ancillary information for the final diagnosis.
- The CT values , SD values and SNR of the pulmonary trunk and arteries (right or left) have a p-value > 0.05; it illustrates that the quality of the images is good enough to diagnose PE.
- D-dimer test showed a high sensitivity (90%) but low specificity (73%), indicating it’s a good investigation to rule out PE in patients but bad indicator of PE in an undiagnosed patient.
Therefore, by combining Spiral CT scan with a D-dimer Test can help diagnose PE successfully, thereby saving lives without any error.
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