Fig. 1

The four typical angiographic images by the “Direct tip Injection in Occlusive Lesions (DIOL)” fashion. A Intimal injection: microchannels which are tiny and relatively straight route without contrast stain (yellow arrow), the branch which is connected with microchannels created by an intimal injection (orange arrow), and a “tubular” dissection which is a subintimal space connected with microchannels (red arrow). B Subintimal injection: a “tubular” dissection (red arrow). A vasa vasorum (white arrow), a venous vasa vasorum, and veins (blue arrow), which are connected among them, are occasionally seen by a forceful injection in subintima. C Intramedial injection: a “river” dissection (green arrow), and the branch which is connected with intramedial space created by an intramedial injection (orange arrow). D Periadventitial injection: a “cloudy” contrast stain as an extravasation (black arrow)