Respiratory-synchronized digital subtraction angiography based on a respiratory phase matching method

Catheter-based therapy is typically performed under fluoroscopic image observation. However, the vessel structure cannot be visualized on fluoroscopic images. To overcome this limitation, angiographic images are captured with a contrast agent, and digital subtraction angiography (DSA) images are acquired during the intervention. In thoracoabdominal DSA, patients have to hold their breath to match the respiratory phase during DSA acquisition. However, breath holding is difficult for some patients, including the elderly. If the organs move during DSA acquisition, artifacts can occur on DSA images, and the DSA acquisition must be performed again. In the present study, we describe and characterize a new respiratory phase matching method for respiratory-synchronized DSA acquisition under natural respiration. Preoperative angiographic and intra-operative fluoroscopic images were collected under natural respiration during the operation. For each fluoroscopic image, we used a pattern matching to select an angiographic image in the most similar respiratory phase. We then examined whether the method could be applied to both the free breathing DSA and the respiratory-synchronized roadmap. We found that our proposed respiratory phase matching method produced acceptable DSA images without breath holding, and that the processing could be performed in real time.