In 21 patients with chronic aortic dissections and proven patent false lumens, the flow volume and flow patterns in the patent false lumens was evaluated using velocity-encoded cine magnetic resonance imaging (VENC-MRI) and the relationship between the flow characteristics and aortic enlargement was retrospectively examined. Flow patterns in the false lumen were divided into 3 groups: pattern A with primarily antegrade flow (n=6), pattern R with primarily retrograde flow (n=3), and pattern B with bidirectional flow (n=12). In group A, the rate of flow volume in the false lumen compared to the total flow volume in true and false lumens (%TFV) and the average rate of enlargement of the maximum diameter of the dissected aorta per year (deltaD) were significantly greater than in groups R and B (%TFV: 74.1+/-0.07 vs 15.2+/-0.03 vs 11.8+/-0.04, p<0.01; deltaD: 3.62+/-0.82 vs 0 vs 0.58+/-0.15 mm/year, p<0.05, respectively). There was a significant correlation between %TFV and deltaD (r=0.79, p<0.0001). Evaluation of flow volume and flow patterns in the patent false lumen using VENC-MRI may be useful for predicting enlargement of the dissected aorta.

therosclerosis of the carotid artery is the primary cause of stroke, and cerebral infarction is the major cause of death. Infarction occurs secondary to plaque ulceration, thrombosis, and intraplaque hemorrhage. [1][2][3] The stability of atheroma has been investigated by angiography, ultrasound, and magnetic resonance angiography (MRA) and of these, angiography is the standard imaging technique for diagnosing arterial stenosis. However, not only the extent of stenosis but also the features of the atheroma are important in determining the risk of clinical events. Some atheromatous plaques are stable, whereas others are fragile. Because emboli from atheroma are involved in the pathogenesis of transient ischemic attacks, changes in the components of atheroma are also important. The gold standard for determining these features of atheroma is still histological examination.We have been investigating noninvasive techniques for the detection of atheroma and MRA is a noninvasive alternative to conventional angiography. 4,5 With respect to magnetic resonance imaging (MRI), it has been reported that intraluminal lesions appear as a signal void within the high signal intensity blood on 2-dimensional time-of-flight (2D-TOF) images, 6 whereas the components of the atheroma can be detected on spin-echo (SE) images. [7][8][9] In the present study, we attempted to detect atheroma of the carotid arteries by 2D-TOF and investigated whether the features of atheroma had any relation to cardiovascular risk factors. Japanese Circulation Journal Vol.65, March 2001 Methods SubjectsThirty-seven subjects with hyperlipidemia (HL), hypertension (HT), and/or diabetes mellitus (DM) were studied by MRI (19 men with a mean age of 62.9±10.0 years; 18 women aged 62.9±10.6 years). Each gave informed consent. Hyperlipidemia, defined as a serum total cholesterol level >220 mg/dl was present in 30 subjects (15 men), HT in 28 cases (14 men), and DM in 14 cases (10 men) ( Table 1). Two patients had cerebral infarction associated with carotid stenosis. MRIMRI (Signa Horizon 1.5 T ver 5.7, GE Yokokawa Medical Co, Tokyo, Japan) was performed with the following pulse sequences: 2D-TOF images: repetition time (TR): 20 ms, echo time (TE): 5 ms, flip angle: 60°, slice thickness: 3 mm, field of view (FOV): 20×20 cm, cardiac gating; T1-weighted SE images: TR: gating (800-1,200 ms), TE: 23 ms, slice thickness: 3 mm, FOV: 12×12 cm, matrix: 256×192, cardiac gating; T2-weighted SE images: TR: gating (2,100-3,800 ms), TE: 80 ms, slice thickness: 3 mm, FOV: 12×12 cm, matrix: 256×192, cardiac gating; proton density (PD) SE images: TR: gating (2,100-3,800 ms), TE: 23 ms, slice thickness: 3 mm, FOV: 12×12 cm, matrix: 256×192. Atheroma appears as a very low signal intensity area on 2-dimensional time-of-flight (TOF) magnetic resonance (MR) images, and its components have various signal intensities on spin-echo (SE) images. The present study investigated atheroma of the carotid arteries in 37 subjects with risk factors (63±10 years of age; 19 men) by magnetic resonance ...