Kazuyoshi Suga MD, Presenter: Nothing to Disclose

Yasuhiko Kawakamii, Abstract Co-Author: Nothing to Disclose

Naofumii Matunaga MD, Abstract Co-Author: Nothing to Disclose

Hideeyuki Iwanaga MD,PHD, Abstract Co-Author: Nothing to Disclose

Actual effects of intravascular clots on peripheral lung perfusion/CT attenuation in pulmonary thromboembolism (PTE) was assessed using deep-inspiratory breath-hold (DIBrH) SPECT-CT fusion images.

Subjects were 14 acute and 9 chronic PTE patients (pts) and 13 control subjects, who successfully underwent DIBrH perfusion SPECT using a dual-headed SPECT system and a respiratory tracking device. DIBrH SPECT was three-dimensionally co-registered with unenhanced and angiographic CT, and regional perfusion, CT attenuation and intravascular clots were correlated on these fusion images.

Fusion images visualized hypo-attenuation areas in 8 (57%) acute and 8 (88%) chronic PTE pts, which preferentially occurred at extensively- and severely- decreased perfusion areas. Although there were no significant differences in lung CT attenuation between the symmetrical right and left lung portions in the normal controls, CT attenuations at 35 large perfusion defects of acute PTE and at 18 large defects of chronic PTE were significantly decreased compared with that of the contralateral normal lungs (-851 HU ± 43 vs -838 HU ± 49; P < 0.001, and -862 HU ± 27 vs –831 HU ± 23; P < 0.0001, respectively). Fusion images also revealed variable relationships of clots and regional perfusion/attenuation in the distal lungs of each central clot. All the perfusion defects with hypo-attenuation areas had various size intravascular clots within corresponding proximal pulmonary arteries. However, no defect or only small, subsegmental defects were seen without attenuation abnormality regardless of the presence of those centrally-located clots in 2 (14%) acute and 2 (22%) chronic PTE pts, and a total of 18 subsegmental/segmental defects were seen without noticeable central or segmental branch’s clots in 3 (21%) acute and 4 (44%) chronic PTE pts.

Fusion images provide important information of actual effects of intravascular clots on peripheral perfusion/CT attenuation, and indicate that CT attenuation can be decreased at perfusion defects even in acute PTE.

Fusion images provide actual effects of intravascular clots on peripheral perfusion/CT attenuation.

Suga, K, Kawakamii, Y, Matunaga, N, Iwanaga, H, Actual Effects of Intravascular Clots on Peripheral Lung Perfusion/CT Attenuation in Pulmonary Thromboembolism: Assessment with Breath-hold SPECT-CT Fusion Images.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4442098.html