This is a 62-years old patient with occasional breathlessness and chest pain, who could not participate properly in a stress test due to osteoarthritis of the knees. His calcium score was 350
The CT shows a severely stenotic lesion in the mid-RCA (Fig. 1), distal to a dense calcific plaque, which completely obscures the lumen. The mid-LAD (Figs. 2, 3) also shows dense calcification preventing adequate lumen visualization, but with a sense that the LAD is significantly abnormal. The catheter angiography shows a severe RCA lesion (Fig. 4), which also involves the lumen not seen due to the calcified plaque on the CT, but shows that the mid-LAD area is essentially normal (Fig. 5).
This case illustrates the problems with calcium. Our growing experience is that with calcification, unless it is on the surface and the lumen is well visualized eccentrically on a high-resolution filter (B46 for Siemens), it is very difficult to comment on the lumen through dense calcification. We both miss and overdiagnosis lesions, as seen in the RCA and LAD, in this case and the more we include patients with high calcium scores in our practice, the more it is likely that we will make mistakes. This has been very well illustrated in a new article, on 149 unselected patients, published recently in the European Heart Journal, reviewed in our accompanying literature blog, as well as in an older article by Achenbach's group last year, in a smaller series of 33 patients.
The pattern of calcification also makes a difference. Often on a calcium score, we do get a sense of whether the calcification will be on the surface or whether it is dense and may obscure lumen, and we have now started taking a call, not just on the basis of the calcium score, where we routinely don't scan patients with scores above 800, but also on the basis of the pattern of calcification. Even if the calcium score is below 800, in the presence of what seems like, lumen-obscuring dense calcifciation, unless the patient specifically requests us to continue, we do not proceed with the study.
The previous case and the case that will be put up next Tuesday, show how well 64-slice CT does with non-calcified lesions, but this and a similar case to be put up next week show how calcification can really make things difficult for us.