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Non-gated high-pitch computed tomography aortic angiography: Myocardial perfusion defects in patients with suspected
Li-Ting Huang1, Shih-Hung Chan2, Chia-Chang Chuang3
1Department of Diagnostic Radiology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No.138, Sheng Li Road, Tainan, 704, Taiwan ROC.
Insights
Myocardial perfusion defects on non-gated computed tomography angiography (CTA) show high specificity for identifying acute myocardial infarction (AMI) in emergency patients. However, sensitivity is low, meaning this method is better at ruling out AMI than confirming it.
Area of Science:
- Cardiology
- Radiology
- Emergency Medicine
Background:
- Acute myocardial infarction (AMI) is a critical diagnosis in emergency departments.
- Computed tomography angiography (CTA) is increasingly used for diagnosing aortic dissection.
- Non-gated high-pitch CTA may offer insights into myocardial perfusion.
Purpose of the Study:
- To evaluate the diagnostic utility of myocardial perfusion defects detected on non-gated high-pitch CTA for identifying AMI.
- To assess the sensitivity, specificity, and predictive values of these perfusion defects.
Main Methods:
- 174 emergency department patients with suspected aortic dissection underwent high-pitch CTA.
- Patients were classified into diseased (AMI) and control groups based on clinical criteria.
- Myocardial perfusion defects were assessed qualitatively and quantitatively on late arterial phase images.
Main Results:
- 12 out of 22 patients with AMI showed visually identifiable perfusion defects.
- Sensitivity for detecting AMI was 54.6%, specificity was 94.7%.
- Quantitative analysis revealed significantly lower CT attenuation in perfusion defects (67.6 HU) compared to normal myocardium (92.2 HU).
Conclusions:
- Myocardial perfusion defects on non-gated high-pitch CTA can identify patients with AMI with high specificity.
- The low sensitivity indicates this finding is not a definitive rule-in for AMI.
- This imaging finding is useful for ruling out AMI in the emergency setting.
Objectives:
To investigate the diagnostic value of first-pass myocardial perfusion defects visualised in non-gated high-pitch computed tomography angiography (CTA) in patients admitted to the emergency department (ED) for suspected aortic dissection.
Methods:
We recruited 174 ED patients who underwent high-pitch CTA of the aorta because of suspected aortic dissection. We divided these patients into two groups (diseased and control groups) based on whether their clinical data fulfilled the third universal definition of acute myocardial infarction (AMI), specifically an increase in cardiac troponin (cTn) with at least one of the following: (a) symptoms of ischemia; (b) new ST-segment-T wave (ST-T) changes or new left bundle branch block (LBBB); (c) development of pathological Q wave; (d) new loss of viable myocardium or new regional wall motion abnormality; or (e) identification of an intracoronary thrombus by angiography or autopsy. Twenty-two patients with a clinical diagnosis of AMI were placed in the diseased group. Myocardial perfusion defects were evaluated qualitatively and quantitatively on the late arterial phase obtained 50 s post-threshold.
Results:
Of the 22 patients with a final diagnosis of AMI, visually identifiable perfusion defects were observed in 12 patients. The sensitivity, specificity, negative predictive value, and positive predictive value of any perfusion defect for predicting AMI were 54.6%, 94.7%, 93.5%, and 60.0%, respectively. Quantitative analysis indicated that CT attenuation was significantly lower within perfusion defects than within the normal myocardium (67.6 ± 29.5 HU vs. 92.2 ± 19.7 HU; p < 0.001).
Conclusions:
In patients with acute chest pain, the presence of myocardial perfusion defect observed on nongated high-pitch CTA of the aorta can be used to identify individuals with AMI with high specificity, but low sensitivity.