The MR images were reviewed and a grading system was defined based on conduit appearance. An abnor­mal signal was felt to represent thrombosis and/or slowly moving blood within the graft or between the graft and the surrounding native aorta.

If no abnormal signal was identified a grade 1 was given and felt to be representative of normal conduit structure (Fig 2b). If an abnormal signal was present but without compromise of the graft lumen, a grade 2 was given (Fig 3). The presence of abnormal signal at the operative site associated with narrowing or defor­mity of the conduit lumen was assigned a grade of 3 (Fig 4; Table 3).

Both parametric and nonparametric statistics were analyzed in an attempt to quantify significant relation­ships between each independent clinical variable and the dependent variable of MR appearance (consultant statistician: Bruce Dworkin, Ph.D.). generic cialis 20mg

Table 3—Grading System of Aortic Valve Conduits by MR Imaging

Grade
1-

Normal

Grade
2-

Periluminal

signal
without

lumen compromise

Grade
3—

Periluminal

signal
with

lumen compromise

Of the ten patients studied, there were two patients classified as grade 3, four patients as grade 2 and the remaining four patients were classified as grade 1. No significant relationship was found when comparing the preoperative diagnosis (seven ascending aortic dissec­tions and three ascending aortic aneurysms) with the postoperative MR grade. Additionally, the time be­tween the original operative repair and the MR examination was not significantly related to the MR grade. Early postoperative bleeding requiring surgical reexploration to control hemorrhage did not correlate with increased periluminal signal or luminal narrow­ing. Increased signal was observed in six patients, with three of these demonstrating even echo rephasing. The presence of slowly flowing blood and/or thrombus was not predictive of narrowing of the graft lumen.

FIGURE 2. Top, Coronal images

FIGURE 2. Top, Coronal images. Bottom, transverse images. Both demonstrate normal grade 1 appearance of ascending aorta. Signal in descending aorta is flow-related artifact. AA, ascending aortic- conduit; DA, descending aorta; PA, pulmonary artery; SVC, superior vena cava.

In the aorta distal to the operative repair, five patients had MR evidence of dissection in the arch and/or descending aorta. The five other patients had no distal aortic dissection or aneurysm and were judged to be normal. The status of the thoracic aorta distal to the operative repair was not predictive of the MR grade.
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Figure 3. Top trans

FIGURE 3. Top, Transverse images. Bottom, sagittal-oblique images. Both demonstrate signal surrounding ascending aorta (armw) but without luminal compromise —a grade 2 abnormality. AA, ascending aorta conduit; DA, descending aorta; RPA, right pulmonary artery; SVC, superior vena cava.

FicullE 4. Top, Transverse

Figure 4. Top, Transverse images. Bottom, Coronal images. Both at same level as Figure 2. Demonstrates grade 3 changes —periluminal signal with narrowing of conduit (arrow). AA, ascending aortic conduit; DA, descending aorta with dissection and slow How in false lumen; PA, pulmonary artery.