Aortic Diameter, True Lumen, and False Lumen Growth Rates in Chronic Type B Aortic Dissection

OBJECTIVE. The objective of this study was to evaluate growth rates of the aorta, true lumen, and false lumen in chronic type B aortic dissections. MATERIALS AND METHODS. Nineteen consecutive patients with acute type B aortic dissection treated medically between 2000 and 2006 were followed with serial MDCT angiography and MR angiography scans during the chronic phase (mean, 5.3 scans per patient; mean follow-up, 17.9 months). Aortic diameter, true lumen diameter, true lumen area, false lumen diameter, and false lumen area were measured at baseline and at each subsequent follow-up study using 3D workstations. Growth rates were assessed with linear regression analyses. RESULTS. One hundred scans were analyzed. The maximum aortic diameter increased significantly over time at a mean rate of 7.1 mm/y (p = 0.004). False lumen diameter (mean, 6.5 mm/y; p = 0.011), false lumen area (5.35 cm(2)/y, p = 0.013), true lumen diameter (0.79 mm/y, p = 0.01), and logarithm true lumen area (0.13 cm(2)/y, p = 0.02) all increased significantly over time, with greater increases in the size of the false lumen than the true lumen. The overall aortic diameter growth rate was significantly higher in patients who ultimately underwent aortic repair or died (15.4 mm/y) than in patients who did not undergo an intervention (1.8 mm/y, p = 0.008). CONCLUSION. Maximum aortic diameter in type B dissections increases significantly over time, primarily because of the increasing size of the false lumen. Patients with high aortic diameter growth rates are more likely to require endovascular or open surgical aortic repair during the chronic phase.