Dynamic digital radiography: a novel quantitative modality to assess the pulmonary blood flow.

Abstract

A 17-year-old girl with congenital unilateral absence of the pulmonary artery underwent surgical reconstruction of the right pulmonary artery (RPA) with a 6 mm polytetrafluoroethylene vascular graft 15 years ago. She had received stent implantation (S.M.A.R.T® 7.0 × 60 mm) to control the graft stenosis at 10-years-old. Nevertheless, regular hemodynamic assessment with balloon angioplasty was required because of the recurrence of graft stenosis. The current cardiac catheterization demonstrated RPA graft stenosis with a pressure gradient of 34 mmHg (Panel A). Tecnethium-99m-macroaggregated albumin lung perfusion scintigraphy showed decreased perfusion in the right lung (right/left: 20.1%/79.9%) (Panel B). A similar result was achieved in dynamic digital radiography (DDR) captured by a flat panel detector (Aero DR fine®, KONICAMINOLTA, Japan) and a conventional X-ray system (RAD speed Pro®, SHIMADZU, Japan), using a prototype workstation (KONICAMINOLTA, Japan) (right/left: 17.4%/82.6%). (Panel C, and Supplementary data online, Video) Lung perfusion scintigraphy has been a golden standard modality for the quantitative assessment of pulmonary blood flow laterality and is inevitably accompanied by radiation exposure. DDR is a new imaging to visualize small changes in pixel value representing the pulmonary circulation without contrast media.1,2 This imaging system can facilitate both qualitative and quantitative evaluations of the dynamic pulmonary circulation with a low cost, short examination time, and reduced radiation exposure. This convenient and non-invasive method will be an effective and alternative approach to assessing lung perfusion in patients with pulmonary artery stenosis.