Pranav Bhagirath

33 Multimodality imaging for patient evaluation and guidance of catheter ablation for atrial fibrillation centers with high volume practices, necessitating an optimization of the existing work- up. Moreover, on-going technological developments have increased the capability of the individual techniques and permit a single modality approach that can supply consistent and uniform imaging data, applicable during the workup, guidance and evaluation of ablation procedures. A general problem for echocardiography is reproducibility. Varying anatomic planes during follow up exam may cause low inter-observer agreement. In addition TTE significantly underestimates atrial volumes and depends upon operator expertise and acoustic windows for image quality. TEE places a burden on the patient due to involvement of an invasive probe and usage of a sedative/anesthetic prior to the examination. CT has the highest spatial resolution amongst the imaging techniques and is the fastest modality to perform. However, its use is largely limited by radiation exposure, which prohibits its use in routine follow-up. The efforts towards reducing this dosage over the last decade have caused a steep decline but still remain a significant load for the patient ( figure 5 ) (50) . Tissue characterization serves an increasingly important role for ablation and although there is improvement, the current prospects of CT are extremely restricted. Figure 5. The evolution of CT: decreasing radiation dosage. The radiation dosage is significantly reduced when using a 128 slice high pitch technique in comparison with a conventional 64 slice scan. This reduction is more prominent for patients suffering from an arrhythmia during the scan. (Adapted from Thai et al 47 )