Concerning a recent publication on the accuracy of MDCT 64
Sofiane Hadjadj, MD, Montreal, has sent the following question:
concerning a recent publication on accuracy of the MDCT 64:
according to the study published in the NEJM Volume 359:2324-2336 \”The patient-based diagnostic accuracy of quantitative CT angiography for detecting or ruling out stenoses of 50% or more according to conventional angiography revealed an AUC of 0.93 (95% confidence interval [CI], 0.90 to 0.96), with a sensitivity of 85% (95% CI, 79 to 90), a specificity of 90% (95% CI, 83 to 94), a positive predictive value of 91% (95% CI, 86 to 95), and a negative predictive value of 83% (95% CI, 75 to 89\”, what have the opinion of the DSCT expert.
thank you
Pal Suranyi, MD, PhD:
Dear Dr Hadjadj,
Thank you for contacting our website. The referenced article is very intriguing, well written and, indeed, is worth discussing.
If one asked me based on that paper, why I would still prefer a Dual Source scanner, when 64-slice scanners can already perform in the 80s and 90s in terms of specificity and sensitivity, NPV and NNP, my argument would probably include the following two very important points:
- Temporal resolution is crucial in cardiac imaging, and the Dual Source scanner gives you twice the speed with which you can freeze cardiac motion. Therefore, it stands to reason that images should be crisper and more accurate.
- The improved temporal resolution also gives us the ability to scan patients without beta blockers, which is an enormous logistic advantage in our everyday practice here at the Medical University of South Carolina. I also happen to know many private practices around the USA who have chosen the Dual Source for this same reason.
At present, at least in the United States, one of the primary indications for coronary CTA is intermediate probability of CAD, i.e. trying to rule out significant coronary disease and “save” patients from an unnecessary catheterization. In this context, a NPV of 83% as reported in the referenced NEJM article by Miller et al. would mean that almost 2 out of 10 patients with significant coronary artery disease would be erroneously sent home based on the results from a 64 slice scanner. A PPV of 91%, on the other hand, means that 1 out of 10 patients would be catheterized unnecessarily.
The more effective we are at reducing artifacts from heart motion, the better we will be able to visualize arteries and diagnose vessels correctly.
In agreement with the article’s authors, until sufficient evidence is gathered, we can only complement coronary artery catheterization, and judicious patient selection should be exercised when indicating a cardiac CTA.
I am not entirely sure if my response will be satisfactory for you, but if we can be of further assistance, or you have a specific question, we would be more than glad to continue the discussion.
Best regards,
Pal Suranyi , MD, PhD
See another answer to this question
I agree with you Dr Suranyi, but I think with a minimal dose of the new technology and the quality of the images like aquired by the DSCT, there are enough evidence to replace the MIBI with the CTA, and even the core 64 study was negative because of the high threshold of the level of the stenosis(more than 50%), it showed that the cta may point the finger at the target vessel to treat,
on the other hand the ACCURACY trial had better result and was multi vendor study.
Dear Dr. Hadjadj,
Thank you for your reply to my earlier comment.
While I am similarly convinced that cardiac CT will (and should) be utilized more and more, it is important to bear in mind that even if we were able to perfectly visualize all coronary arteries and all segments, with the conventional CT methods we would still not be able to reliably quantify tissue perfusion.
For the assessment of myocardial perfusion, nuclear cardiac scans are considered the gold standard (even though some would argue they are more the “old standard”), and MRI is emerging to compete for becoming the modality of choice.
Newer methodologies, such as dual-energy cardiac CT, which was pioneered here at MUSC, attempting to assess the iodine content of the myocardium, and other efforts aimed at studying myocardial perfusion with CT even during adenosine stress may provide us with the technology in the future that allows us to reliably assess the severity of the coronary artery disease at the tissue level.
On the other hand, CT angiography has another important advantage over conventional angiography, which is the ability to visualize coronary artery plaques. To identify lesions with a high potential of becoming culprit lesions in acute coronary syndromes, it is crucial to differentiate calcified plaques from noncalcified (fibrous and lipid rich) plaques. This is definitely one strength of coronary CTA, with which none of the other modalities can compete with.
Thank you for your continued interest in our website and in promoting cardiac CT. We are looking forward to hearing from you again.
Best regards,
Pal Suranyi , MD, PhD