A novel research has showed that an enhanced identification of pulmonary embolism is possible when two magnetic resonance imaging (MRI) sequences are added to the common MR angiography method.
Pulmonary embolism is a dangerous condition that occurs when a blood clot mostly from the leg reaches the lungs and creates pulmonary arterial blockage. Usually, pulmonary embolism is detected using computed tomography (CT).The iodinated contrast agent and ionizing radiation from CT angiography may cause damage to the kidney and anaphylactic reactions in certain patients.
MRI has been performed on patients prone to kidney damage by iodinated contrast agents in CT angiography and pregnant women. Nevertheless, a multicenter trial, prospective investigation of pulmonary embolism diagnosis III (PIOPED III) study, showed that good quality MR pulmonary angiography (MRPA) were not available in all centers. The study concluded that MRPA must be done in well equipped and high-performance centers and must be performed only to patients who develop contraindications through routine tests.
Dr. Diego R. Martin, heading the Department of Radiology, College of Medicine, University of Arizona at Tucson stated that MRI is fast developing when compared to CT. He added that the quality of images has improved this year and techniques based on non-radiation will replace CT, in future, for pulmonary embolism diagnosis.
In this project, the effect of two additional sequences of MRI on the precision of MRPA was examined. Dr. Martin said that contrast-enhanced volumetric interpolated breath-hold examination (VIBE) and non-contrast true fast imaging with steady-state precession (true FISP) methods can be used with MRPA.
With VIBE, a gray scale is produced that differentiates a thrombus or clot and lungs clearly, whereas, it appears dark on MRPA alone. According to Dr. Martin VIBE is insensitive to time and even if the patient coughs, the test can be repeated which is impossible in MRPA.
Usually, the patients hold their breath for acquiring MRPA images, however, with true FISP, breath hold or contrast agent is not required. A sensitivity of 73%, 67% and 55% was found with VIBE, true FISP and MRPA methods respectively. MRPA alone showed one false positive result.
Dr. Martin expects that PIOPED study to be remodeled based on his new study. The paper has been published online in the journal Radiology.
Source: http://www.rsna.org/