2023 Volume 83 Issue 6 Pages 363-372
Magnetic resonance imaging （MRI） is a noninvasive imaging modality that offers excellent detection accuracy up to the regional pulmonary artery branch, in addition to being able to depict the thrombus itself with a high signal, in order to depict the thrombosis in the pulmonary artery using diffusion weighted imaging （DWI）, resulting in a better contrast than CT. Therefore, We conducted a basic study using imaging phantoms to see if pulmonary artery thrombosis can be depicted by noncontrast MRI. We processed sealed blood samples using DWI over time to determine the signal value for thrombosed blood to calculate the apparent diffusion coefficient （ADC）. Additionally, the DWI signal value and ADC for thrombus formation were measured from a patient with cerebral hemorrhage during thrombus formation. We evaluated the appropriate conditions for detecting thrombosis by changing the echo time （TE） and b-value. The signal-to-noise ratio （SNR） and contrast-to-noise ratio （CNR） were computed and examined as a visual evaluation of the obtained image. The mean DWI signal and ADC values for the thrombus were 210±42 and 470±83mm2/sec, respectively, which concurred with those reported in previous studies. Furthermore, shorter TE was associated with a higher simulated thrombus signal value, SNR, and CNR. Although a higher b-value was associated with a lower SNR for the thrombus, the CNR value reached a peak at a b-value of 1,000s/mm2; it was not significantly change in evaluation score from 800 to 2,000s/mm2. Therefore, pulmonary artery thrombosis can be effectively depicted using noncontrast MRI via DWI by setting a shorter TE and at a b-value of 1,000.
