Non-Invasive Diagnostic Imaging of Peripheral Arterial Disease

CTA could be improved by reducing the impact of vessel wall calcifications on image interpretation. With a 16-slice or recently introduced 64-slice MDCT scanner a higher resolution can be obtained compared to a 4-slice MDCT. This may result in less blooming of calcifications, which will improve image interpretation. However, the potential for radiation dose reduction with the 16- and 64-slice MDCT scanners, due to the differences in gantry geometry compared to a 4-slice MDCT, is lost when we obtain higher resolution images using thinner slices and lower pitch. Subtraction CTA is another approach to minimize the burden of vessel wall calcifications on image interpretation (55). However, this technique requires a high level of patient collaboration, is not feasible in 20% of the patients in spite of good collaboration, generates two times more images, and increases the radiation exposure. The possible solution for the calcification problem may be found in post-processing software or more likely in hardware improvements. A complete different solution lies not in the technique, but in selecting patients for whom CTA is contra-indicated due to extensive vessel wall calcifications. In this thesis we performed an initial evaluation of clinical predictors of vessel wall calcifications on CTA. A future study is needed to develop and validate a clinical prediction rule for this problem. The results from our study can help design such a future study and restrict the data collection to the most relevant variables. In summary, CTA is the optimal non-invasive imaging test for the initial evaluation of patients with PAD. In elderly patients, patients with diabetes mellitus, and those with cardiac disease a CTA is contra-indicated due to decreased clinical utility. In these patients a MRA should be considered as initial imaging test. With the current knowledge of the DIPAD trial it is not useful to perform another study on the costs and effects of non-invasive imaging test for PAD.