Maiko Takahashi MD, Presenter: Nothing to Disclose

Nobusada Funabashi MD, PhD, Abstract Co-Author: Nothing to Disclose

Masae Uehara MD, Abstract Co-Author: Nothing to Disclose

Nobuhiro Tanabe, Abstract Co-Author: Nothing to Disclose

Koichiro Tatsumi, Abstract Co-Author: Nothing to Disclose

Issei Komuro MD, Abstract Co-Author: Nothing to Disclose

Hiroyuki Takaoka MD, Abstract Co-Author: Nothing to Disclose

Toshihiko Suhiura, Abstract Co-Author: Nothing to Disclose

To reduce the redundant acquisition range and total radiation dose for planning appropriate “Triple rule out” CT angiography (CTA) for acute chest pain, we evaluated the detailed distribution of pulmonary thromboemboli (PTE) in subjects with acute PTE.

Retrospective review of CT pulmonary angiography (CTPA) (Light speed ultra 16, GE) in 75 subjects (48 female, 57±16 years) with proven acute PTE was performed to determine whether PTE existed solely above the top of the aortic arch or below the undersurface of the heart.

All 75 subjects (100%) demonstrated PTE in CT: 58 (77%) had PTE in the right upper lobe but none were solely located higher than the top of the aortic arch; 57 (76%) had PTE in the right middle lobe; 65 (87%) had PTE in the right lower lobe, of which 1 (1%) was solely located lower than the undersurface of the heart, but this subject also had PTE in the right upper lobe; 62 (83%) had PTE in the left upper lobe of whom 2 (3%) who had PTE solely located higher than the top of the aortic arch; 57 (76%) had PTE in the left lower lobe, of whom 2 (3%) had PTE solely located lower than the undersurface of the heart; both of these subjects had PTE in the right upper, middle, and lower and left upper lobe. As the acquisition length in limited CTPA in this population was reduced on average 21.9% in comparison with full CTPA, the dose-length product for each examination, from which effective doses were then estimated, would be reduced in the limited CTPA to the same degree (21.9%) in comparison with full CTPA.

In subjects with acute PTE, there were none whose PTE existed solely in the upper lobes which were higher than the top of the arch, nor solely in the lower lobes which were lower than the undersurface of the heart. A limited range CTA protocol for evaluation of PTE only between the top of the arch and the undersurface of the heart could reduce effective doses approximately 22% relative to full chest CTA. A limited range triple rule-out CTA protocol for evaluation of PTE, aortic dissection, and coronary disease would decrease effective doses of CTA and the physician might not miss any PE.

A limited range triple rule-out CT angiography protocol for evaluation of pulmonary thromboemboli aortic dissection, and coronary disease would decrease effective doses of CT angiography.

Takahashi, M, Funabashi, N, Uehara, M, Tanabe, N, Tatsumi, K, Komuro, I, Takaoka, H, Suhiura, T, Detailed Distribution of Acute Pulmonary Thromboemboli: Direct Evidence to Reduce Acquisition Length and Radiation Dose for Triple Rule-Out CT Angiography.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8013928.html