Hypointense boundary layer between slow flow and mural thrombus on spin-echo MR

Diagnosis of Thrombus and Blood Flow in Aortic Aneurysm Using Tagging Cine Magnetic Resonance Imaging

In order to diagnose thrombus and to evaluate blood flow in aortic diseases, we investigated the usefulness of tagging cine magnetic resonance imaging (MRI) in patients with aortic aneurysm and aortic dissection. Six abdominal aortic aneurysms (AAA), two aortic arch aneurysms, and three aortic dissections were examined using tagging cine MRI. Linear tagging bands were 3 or 5 mm wide and established to the long and short axial images of the aortic lesions. Tagging bands were confirmed as the low-intensity signal bands in all patients. The parts of tagging bands of the intraaortic thrombus did not move, whereas the parts of tagging bands of the intraaortic blood flow moved and faded as time passed. Intraaortic thrombi were diagnosed in eight patients (six AAA, one aortic arch aneurysm, and one aortic dissection) in accordance with the stain of the parts of tagging bands. In patients with aortic dissection, the parts of tagging bands in the false lumen moved slowly, whereas the parts of tagging bands in the true lumen moved quickly. Tagging cine MRI has been shown to be useful in the diagnosis of thrombus and blood flow in aortic diseases.

Magnetic resonance images lipid, fibrous, calcified, hemorrhagic, and thrombotic components of human atherosclerosis in vivo

BACKGROUND

Although MRI can discriminate the lipid core from the collagenous cap of atherosclerotic lesions in vitro with T2 contrast, it has not yet produced detailed in vivo images of these human plaque components.

METHODS AND RESULTS

We imaged seven lesions from six patients who required surgical carotid endarterectomy and calculated T2 in vivo before surgery in various plaque regions. Using the same acquisition parameters, we repeated these measurements in vitro on the resected fragment and compared MR images with histology. T2 values calculated in vivo correlate with in vitro measurements for each plaque component; the in vitro discrimination we demonstrated previously with T2 contrast can therefore be performed similarly in vivo.

CONCLUSIONS

MRI is the first noninvasive imaging technique that allows the discrimination of lipid cores, fibrous caps, calcifications, normal media, and adventitia in human atheromatous plaques in vivo. This technique also characterizes intraplaque hemorrhage and acute thrombosis. This result may support further investigations that include MRI of plaque progression, stabilization, and rupture in human atherosclerosis.

Usefulness of turbo-FLASH dynamic MR imaging of dissecting aneurysms of the thoracic aorta

PURPOSE

We attempted to determine whether Turbo-FLASH dynamic magnetic resonance imaging is clinically useful for the diagnosis of dissecting aneurysm of the thoracic aorta by differentiating slow flow from thrombus in the false lumen.

METHODS

Magnetic resonance imaging (MRI) was performed in ten patients using three different pulse sequences (spin echo, cine and turbo-FLASH dynamic MRI). The three imaging techniques were compared for their ability to demonstrate anatomical and hemodynamic abnormalities by visual assessment.

RESULTS

In all patients with thrombus in the false lumen, the thrombus was accurately differentiated from slow flow on contrast enhanced turbo-FLASH dynamic MRI, but only with difficulty on spin echo and cine MRI. Dynamic MRI was also useful for the evaluation of flow dynamics in the false lumen.

CONCLUSION

Turbo-FLASH dynamic MRI is recommended for patients with dissecting aneurysm of the thoracic aorta, not definitely diagnosed by spin echo and cine MRI.