Rie Tanaka PhD, Presenter: Nothing to Disclose

Shigeru Sanada PhD, Abstract Co-Author: Stockholder, Hologic, Inc (R2 Technology, Inc), Sunnyvale, CA Research grant, Canon Inc, Tokyo, Japan

Masaki Fujimura MD, Abstract Co-Author: Nothing to Disclose

Nobuo Okazaki MD, Abstract Co-Author: Nothing to Disclose

Kazuya Nakayama PhD, Abstract Co-Author: Nothing to Disclose

Takeshi Matsui, Abstract Co-Author: Nothing to Disclose

Osamu Matsui MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Pulmonary and cardiac blood circulation is indicated by the changes in pixel values during cardiac pumping on dynamic chest radiographs. Thus, decreased blood flow is indicated as a reduction of changes in pixel values. This study was performed to investigate the feasibility of non-contrast enhanced perfusion imaging with a dynamic flat-panel detector (FPD) and determine the clinical usefulness in pulmonary diseases.

Dynamic chest radiographs of 10 subjects (ischemic heart disease, emphysema, and normal controls) were obtained at end expiration using an FPD system, in combination with electrocardiograms (ECG) monitoring. Changes in pixel values during cardiac pumping were measured, then visualized by inter-frame subtraction and color mapping technique. Changes in pixel value were correlated with those in blood volume using a water equivalent step phantom.

There was a strong correlation between cardiac cycle and changes in pixel value, shown as ±1.1% in the left ventricle, ±0.7% in other heart areas and from ±0.2 to 0.4% in the lung areas during heartbeat period. On color mapping images, decreased blood flow was indicated as a reduction of changes in pixel values due to decreased inter-frame differences. Phantom study indicated that ±1.0% in pixel value was equivalent to ±10 mm of water and that perfusion defect up to 4 mm in diameter could be detected. These findings supported the concept that changes in pixel value measured in clinical cases were caused by blood circulation.

Dynamic chest radiography using an FPD was capable of quantifying local blood flow. Changes were quantified and visualized as perfusion images by inter-frame subtraction and color mapping technique. These images would aid radiologists in interpreting pulmonary blood flow on dynamic chest radiographs. The present method is expected to provide rapid and simple perfusion imaging without contrast media.

The present method using inter-frame subtraction technique has potential as a simple perfusion imaging method as well as an optional function in cone beam CT or 4DCT.

Tanaka, R, Sanada, S, Fujimura, M, Okazaki, N, Nakayama, K, Matsui, T, Matsui, O, et al, , et al, , Computer-aided Perception of Circulatory Dynamics on Chest Cine X-ray Using Inter-frame Subtraction Technique.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5007328.html