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Preferential location of acute pulmonary thromboembolism induced consolidative opacities: assessment with respiratory gated perfusion SPECT–CT fusion images

Zaki, Mohammed; Suga, Kazuyoshi; Kawakami, Yasuhiko; Yamashita, Tomio; Shimizu, Kensaku; Seto, Aska; Matsunaga, Naofumi

Nuclear Medicine Communications: May 2005 - Volume 26 - Issue 5 - p 465-474
ORIGINAL ARTICLES
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Purpose Preferential location of acute pulmonary thromboembolism (PTE) induced consolidative opacities (infarction/atelectasis) was determined on respiratory gated perfusion SPECT–CT fusion images.

Method Gated end-inspiratory perfusion SPECT images were obtained in 21 patients with acute PTE and 17 patients with inflammatory diseases, using a triple-headed SPECT system and a respiratory tracking device. Anatomical relationships of consolidative opacities and perfusion defects were assessed on gated SPECT–rest inspiratory CT fusion images. The size and radioactivity of perfusion defects with acute PTE consolidative opacities were compared with those of defects without these opacities. The contribution of fusion images for differential diagnosis of acute PTE induced and inflammatory disease induced lesions was evaluated by receiver operating characteristic (ROC) curve analysis.

Results Of the total 56 acute PTE induced consolidative opacities, 42 (75%) were located at the peripheral interface between the severely decreased and adjacent relatively preserved perfusion areas within wedge shaped perfusion defects on fusion images. These defects with consolidative opacities were significantly larger and had taken up less radioactivity compared with those in the 86 defects without these lesions (P<0.0001). In contrast, of the 29 inflammatory disease induced opacities, 14 (48.2%) had the matched defects and 13 (44.8%) were located at the proximal portion of defects. These preferential locations of acute PTE induced and inflammation induced lesions were significantly different (P<0.01). In ROC curves, the combined reading of fusion images showed a significantly higher differential diagnostic accuracy compared with the reading of CT and SPECT images alone (P<0.01).

Conclusions Acute PTE induced consolidative opacities preferentially occur at the peripheral lung interface between severely decreased and adjacent relatively preserved perfusion areas within relatively large and severely decreased perfusion defects. The fusion images, which provide an accurate assessment of the morphological–perfusion defect relationship could, potentially, provide a differential diagnosis between acute PTE induced and inflammatory disease induced lesions.

Department of Radiology, Yamaguchi University School of Medicine, Japan

Sponsorship: This study was supported in part by a research grant for scientific research (08671033) from the Japanese Ministry of Education.

Correspondence to Dr Kazuyoshi Suga, Department of Radiology, Yamaguchi University School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8505, Japan

Tel: +81 836 22 2283; fax: +81 836 22 2285;

e-mail: sugar@po.cc.yamaguchi-u.ac.jp

Received 1 October 2004 Accepted 25 January 2005

Part of this study was presented at the SNM 51st Annual Meeting (No. 990), Philadelphia, USA.

© 2005 Lippincott Williams & Wilkins, Inc.