What are the expected benefits of SR-DLR in cardiac CT?
1/ An increased perceived Image Quality
In cardiac CT – including coronary CTA, valve CT and myocardium analysis, perceived image quality is higher with SR-DLR when compared to DLR and Hybrid IR. This increased image quality appears to be the resultant of a combination of factors.
A/ Significant noise reduction (Figure 4)
- Even compared with DLR, with about an additional 20% reduction
- This reduction is present in the whole CT slice – even outside the heart.
B/ Increased sharpness (Figure 5)
- Conspicuity of structures and contours is better seen; even on subtle lesions
- This is better seen on curved MRPs (Figure 6).
C/ Better delineation of small structures (Figure 7)
- Such as small arterial branches.
D/ Increased conspicuity of calcifications (Figure 8)
- Mostly perceived on faint/low density calcifications.
2/ A better evaluation of highly calcified vessels and stents
All the above contributes to a better luminal depiction and analysis in calcified vessels and stents.
We have shown (ECR 2023) that potential CAD-RADS 3 lesions are differently evaluated when using SR-DLR, with a significant rate of downstaging (up to 35%).
3/ A better detection of minimal atherosclerosis
All the above, and particularly the increased conspicuity of calcifications, can also enhance the detection of minimal parietal lesions.
We have shown (ECR 2022 – Figure 9) that in patients with no to minimal coronary artery disease on conventional CT (whether IR or DLR), the use of SR-DLR will significantly increase the total number of detected abnormal segments. This could be indicative of a better depiction of early atherosclerotic lesions when using SR-DLR.
What are the drawbacks of SR-DLR in cardiac CT?
1/ Blooming artifacts can be moderately increased in case of nodular or extremely dense calcifications (Figure 10).
2/ SR-DLR is currently limited to one vendor and only one type of machine (4th generation wide-area detector CT).
What are the expected evolutions of SR-DLR in the coming months/years?
1/ 1024 matrix size
- Currently, SR-DLR produces images only with a 512x512 matrix, thus limiting the theoretically increased spatial resolution
- Future updates will allow to produce images with a 1024x1024 matrix size, with promising results on image quality and particularly sharpness of arterial wall and plaque (Figures 11 and 12).
2/ Other anatomy
- SR-DLR is currently limited (trained) to cardiac CT. As for DLR, the technology could be developed for any anatomy and could also be extended to MR image reconstruction.