Yutaka Tanami MD, Presenter: Nothing to Disclose

Masahiro Jinzaki MD, Abstract Co-Author: Nothing to Disclose

Kiyotaka Nakajima, Abstract Co-Author: Nothing to Disclose

Akihisa Yamazaki RT, Abstract Co-Author: Nothing to Disclose

Koichi Sugisawa RT, Abstract Co-Author: Nothing to Disclose

Sachio Kuribayashi MD, Abstract Co-Author: Research grant, General Electric Company

Yasuhiro Imai MS, Abstract Co-Author: Employee, General Electric Company

Kosuke Sasaki MS, Abstract Co-Author: Employee, General Electric Company

Kazuhiro Matsumoto MD, Abstract Co-Author: Nothing to Disclose

Minoru Yamada MS, Abstract Co-Author: Nothing to Disclose

The loss of intra-vertebral fat is important for diagnosis of bone metastasis in T1 weighted image using MRI, although it is difficult to evaluate intra-vertebral fat using conventional CT. A spectral imaging with fast kVp switching CT could potentially differentiate between bone minerals and the intra-vertebral fat. Moreover, fat/bone material decomposition images (fat equivalent images) could be reconstructed using spectral imaging. Our purpose is to evaluate the feasibility of “fat equivalent image“ for the diagnosis of bone metastasis.

Thirty patients with the history of malignancy (breast ca.: 18, lung ca.: 5, prostate ca.: 4, colorectal ca.: 3), underwent CT utilizing a 64-row CT (Discovery CT750 HD: GE Healthcare WI) scanner and nuclear study with 99mTc-MDP within one month. CT scan was performed with fast kVp switching by 80kVp and 140kVp. Fat equivalent images were reconstructed by spectral imaging. In patients without bone metastasis, regions of interest (ROI) were placed in the vertebral bodies of Th-1, 3, 5, 7, 9, 11, L-1, 3, 5. In patients with bone metastases, ROIs were placed in the metastatic part of vertebra with the reference of nuclear studies. For statistical analysis, unpaired t-test was used.

The representative fat equivalent image was shown as figure. Nuclear studies revealed that 10 patients had 34 vertebral bone metastases. At normal vertebra, the average pixel value of fat equivalent images were 987±67, 961±30, 960 ±27, 964±25 , 964±26, 962±27, 957±35, 954±35, 952 ±41 at Th-1,3,5,7,9,11,L-1,3,5, respectively. The average pixel value at bone metastases was 1032±60. The pixel value of the bone metastases was significantly higher than that of normal vertebra(P<0.05). CTDIvol was 12.72mGy.

Fat equivalent image is feasible for the detection of bone metastasis by spectral imaging with fast kV switching CT.

Fat equivalent image by spectral imaging has a potential to make a diagnosis of bone metastasis.

Tanami, Y, Jinzaki, M, Nakajima, K, Yamazaki, A, Sugisawa, K, Kuribayashi, S, Imai, Y, Sasaki, K, Matsumoto, K, Yamada, M, Feasibility of Fat Equivalent Image Using Spectral Imaging with Fast kVp Switching Computed Tomography in the Diagnosis of Bone Metastasis.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9003061.html