Double precardinal anastomoses with interconnecting venous plexus hypothesis in the embryogenesis of anomalous brachiocephalic veins: Computed tomography and magnetic resonance findings

Purpose: The aim of this study was to assess the hypothesis of double precardinal transverse anastomoses with an interconnecting venous plexus in the embryogenesis of anomalous brachiocephalic veins (ABCV) based on computed tomography (CT) and magnetic resonance (MR) findings. Materials and Methods: Between January 2000 and September 2009, of 25,940 thoracic CT or MR imaging studies, 27 patients with developmental ABCV were encountered in our institution. Among them, 15 pediatric patients underwent CT or MR studies due to suspected complex thoracic vascular anomalies that were not well defined on echocardiograms. In the other 12 adult patients, ABCVs were incidentally found during cancer workup or evaluation of mediastinal widening seen on the chest radiographs. The anatomic variations of ABCV demonstrated on CT or MR imaging were retrospectively reviewed, and the implications of ABCV variations in the embryogenesis of ABCV were assessed. Results: Five types of ABCV were revealed: supraaortic retrovascular left ABCV (n=1), left subaortic ABCV (n=6), double superior venae cavae with hypoplastic bridging ABVC (n=5), double superior venae cavae with absence of the brachiocephalic vein (BCV) (n=14), and double left BCV (n=1). The 5 types of ABCV could be explained by the persistence and regression of different parts of the double precardinal transverse anastomoses and interconnecting venous plexus. CT also demonstrated interconnecting veins to the BCV in 1 case and nipple-like remnants of interconnecting veins on the BCV in 2 cases, providing direct imaging evidence of the presence of the interconnecting veins. Conclusion: The hypothesis of double precardinal anastomoses with interconnecting veins offers a concise but comprehensive explanation of various kinds of ABCV.