الفهرس 
Established Imaging Modalities for Cardiac DiagnosisOnly 14 pages are availabe for public view
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Abstract
Coronary artery by pass graft (CABG) surgery is the standard therapy in the majority of diffuse coronary diseases or multivessel diseases. However, recurrent angina experienced by individuals who have previously undergone coronary artery bypass surgery is a common clinical problem with its further limitation of life quality;
At present, coronary angiography represents the gold standard technique for the evaluation of bypass conduits and diagnosis of coronary artery disease.
In this study, our aim was comparing the coronary 64-multislice spiral computed tomography (64-MSCT) to the conventional coronary angiography in patients with post CABG angina, a new and non-invasive cardiac imaging technique. The study included 45 patients scheduled for elective invasive coronary angiography for post CABG angina. Patients with arrhythmia, renal impairment, known contrast allergy or any cardiac instability were excluded from the study.
All patients had the MSCT conducted using a 64-slice Toshiba CT scanner with 64X0.6 mm collimation. The contrast was injected intravenously using a dual head power injector. All patients received non ionic, low osmolar contrast. The bolus tracking technique was used, the scan was automatically started when the contrast reached a peak concentration in the left side of the heart. All the scan were ECG gated. The ECG gating was used to retrospectively reconstruct the datasets at the mid to late diastolic phase of each cardiac cycle (75%). Few scans needed an additional systolic reconstruction to better visualize some non evaluated segments on diastolic reconstruction. Heart rate control was attempted in every patient. Patients with uncontrolled heart rates were excluded from the study.
All patients had their invasive coronary angiographies done within a 2weak interval from the MSCT. Both the MSCT and invasive coronary angiography data were evaluated by operators blinded to the results of the other test.
MSCT data were evaluated using the transaxial images, as well as other reconstruction modalities; multiplanar reconstructions, MIP and curved MPR. A 15-segment coronary tree model was used. Each segment was evaluated both with MSCT and coronary angiography. All grafts were divided into proximal mid and anastomotic site segments. By MSCT segments were labeled either with significant stenosis (≥70% luminal narrowing) or with no significant stenosis (< 70% luminal narrowing).
Non evaluable coronary segment were also recorded. Using invasive coronary angiography each coronary segment was labeled either normal or atherosclerotic with the degree of luminal stenosis recorded. Failure to cannulate or visualize the graft even after aortic root injection was considered to indicate an occluded graft.
A total number of 300 vessels were evaluated. They were divided into 180 native coronary vessels and 120 grafts. Of the 120 bypass grafts evaluated, 46 were arterial grafts and 74 were venous grafts (SVG).
For the native vessels, in a ’per segment’ analysis, MSCT could detect significant disease with a sensitivity and specificity of (90% and 94% respectively), with a very good overall positive predictive value of 90% and a negative predictive value of 94%. In a ’per vessel’ analysis, the sensitivity and specificity were (96% and 91% respectively), with a very good overall positive predictive value of 95% and a negative predictive value of 94%.
For the arterial grafts, in a ’per segment’ analysis, MSCT could detect significant disease with a sensitivity and specificity of 100% and 99%, with a PPV of 91% and NPV of 100% with a diagnostic accuracy of 99%. In a ’per graft analysis, MSCT could detect significant disease with a sensitivity and specificity of 100% and 97%, with a PPV of 91% and NPV of 100% with a diagnostic accuracy of 98%.
For the venous grafts, per segment analysis, we reported a sensitivity of 100% and specificity of 99%, PPV of 97% and NPV of 100% with a diagnostic accuracy of 99%. In a ’per graft analysis, MSCT could detect significant disease with a sensitivity and specificity of 100% and 97%, with a PPV of 97% and NPV of 100% with a diagnostic accuracy of 99%.