History
A 70-year-old woman complained about dyspnea and chest discomfort on exertion. The symptoms gradually worsened and she was referred to our center with suspicion of acute coronary syndrome. An ECG was almost normal, but laboratory test results showed mild, increased fibrinogen, and Ultrasound Cardiography (UCG) showed right ventricle dilatation and tricuspid regurgitation. From these results, we suspected pulmonary thromboembolism and ordered a Dual Energy CT scan.
Diagnosis
The first Dual Source CT examination in the Dual Energy mode was taken at 11:30. The mixed images revealed thrombi in both pulmonary artery trunks reaching into the branches and the patient was diagnosed with pulmonary embolism. Dual Energy lung perfused blood volume (PBV) images showed perfusion defects in the right lung and the left lingular and lower lobe corresponding to the location of the thrombus. Heparin therapy was started. Thrombolytic therapy was planned, and then an Inferior Vena Cava (IVC) filter was placed. The patient felt instant relief from dyspnea and therefore a follow-up Dual Energy CT scan was performed at 16:30.
The mixed CT images revealed that the thrombus was unchanged compared to five hours earlier. Yet, the Dual Energy lung PBV images showed that the patient’s lung perfusion had improved.
Considering the patient’s age and physical condition, a wait-and-see approach was decided and anti-coagulation with heparin and warfarin were continued. The patient’s symptoms gradually improved. One week later we confirmed on Dual Energy Lung PBV images that perfusion had improved in large parts, but slightly decreased perfusion was still seen in the mid-right lobe and upper left and left lingular segments. The thrombus had disappeared on the mixed CT images. Two weeks later, the patient underwent perfusion and ventilation scintigraphy. Now, only a small mismatch between the images was seen at the periphery of the middle lobe of the right lung and the lingular segment of the left lung.
The mixed CT images revealed that the thrombus was unchanged compared to five hours earlier. Yet, the Dual Energy lung PBV images showed that the patient’s lung perfusion had improved.
Considering the patient’s age and physical condition, a wait-and-see approach was decided and anti-coagulation with heparin and warfarin were continued. The patient’s symptoms gradually improved. One week later we confirmed on Dual Energy Lung PBV images that perfusion had improved in large parts, but slightly decreased perfusion was still seen in the mid-right lobe and upper left and left lingular segments. The thrombus had disappeared on the mixed CT images. Two weeks later, the patient underwent perfusion and ventilation scintigraphy. Now, only a small mismatch between the images was seen at the periphery of the middle lobe of the right lung and the lingular segment of the left lung.
Comments
In the past, scintigraphy was used for PE diagnosis. In recent years however MDCT has replaced scintigraphy for PE diagnosis. The diagnosis can be done by confirming clots in vessels with CT. In the case of this patient, PE could be diagnosed on single Energy CT, but the reason for the improvement of clinical symptoms could not be confirmed. Only with PBV images acquired by Dual Energy CT could we presume that pulmonary perfusion improvement was the cause for the relief of the symptoms. Perhaps this was the result of an increased blood flow around the thrombus, which was too small to be seen from the state of the thrombus itself. Only functional images (meaning perfusion images) could reveal it. We were able to see this small change with only one Dual Energy CT scan. Dual Energy Lung PBV was extremely helpful in this case.
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