Characterization of lipid-rich aortic plaques by intravascular photoacoustic tomography: ex vivo and in vivo validation in a rabbit atherosclerosis model with histologic correlation.

Characterization of lipid-rich aortic plaques by intravascular photoacoustic tomography: ex vivo and in vivo validation in a rabbit atherosclerosis model with histologic correlation.

Zhang J, Yang S, Ji X, Zhou Q, Xing D.

J Am Coll Cardiol. 2014 Jul 29;64(4):385-90



Histologic studies have demonstrated that lipid content and its spatial distribution is related to plaque vulnerability. However, in vivo imaging is still limited. Photoacoustic imaging may provide novel in vivo insights into these lipid-rich plaques.


This study sought to examine whether intravascular photoacoustic tomography (IVPAT) allows localization and quantification of lipid content in atherosclerotic plaques.


Rabbits fed with a high-fat/high-cholesterol diet served as the atherosclerotic model. Catheter-based IVPAT was used to evaluate pixel-based lipid relative concentration (LRC) of the vessel wall. The aorta of 4 groups of rabbits (n = 12) were examined ex vivo with IVPAT after 0, 5, 10, and 15 weeks of a high-fat diet, respectively. Six rabbits underwent 3-dimensional (3D) IVPAT after 20 weeks of the high-fat diet. Three rabbits were examined in vivo using IVPAT without interruption of blood flow. Concentration-based lipid map and quantitative index were calculated. For subsequent histologic correlation, all specimens were evaluated with Oil Red O staining.


Cross-sectional LRC maps allowed visualization of concentration and depth information of lipid content in the atherosclerotic plaques. Lipid accumulation within plaque, assessed by the maximum LRC, mean LRC, and high lipid content area correlated to duration of a high-fat diet. Three-dimensional LRC maps enabled overall evaluation of focal plaques in an intact explanted aorta including spatial and structural features. In vivo-obtained LRC maps accurately showed the structure of lipid core with high contrast. Ex vivo and in vivo IVPAT results were highly consistent with histological results.


In an animal model, IVPAT allowed characterization of spatial and quantitative features of lipid-rich plaques.


Aggregate plaque volume by coronary computed tomography angiography is superior and incremental to luminal narrowing for diagnosis of ischemic lesions of intermediate stenosis severity.

Aggregate plaque volume by coronary computed tomography angiography is superior and incremental to luminal narrowing for diagnosis of ischemic lesions of intermediate stenosis severity.
Nakazato R, Shalev A, Doh JH, Koo BK, Gransar H, Gomez MJ, Leipsic J, Park HB, Berman DS, Min JK.
J Am Coll Cardiol. 2013 Jul 30;62(5):460-7.

Intravascular Photoacoustic Tomography

JACC Original Investigation July 2014

Characterization of Lipid-Rich Aortic Plaques by Intravascular Photoacoustic Tomography
Ex Vivo and In Vivo Validation in a Rabbit Atherosclerosis Model With Histologic Correlation

Jian Zhang, PhD∗; Sihua Yang, PhD∗; Xuanrong Ji, PhD∗; Quan Zhou, MD†; Da Xing, PhD∗

Effect of reduced radiation exposure and iterative reconstruction on detection of low-contrast low-attenuation lesions in an anthropomorphic liver phantom: an 18-reader study.

Radiology. 2014 Jul;272(1):154-63. doi: 10.1148/radiol.14131928. Epub 2014 Mar 10.

Effect of reduced radiation exposure and iterative reconstruction on detection of low-contrast low-attenuation lesions in an anthropomorphic liver phantom: an 18-reader study.

Goenka AH1, Herts BR, Obuchowski NA, Primak AN, Dong F, Karim W, Baker ME.

Author information


Purpose To measure the effect of reduced radiation exposure on low-contrast low-attenuation liver lesion detection in an anthropomorphic abdominal phantom by using filtered back projection (FBP) and sinogram-affirmed iterative reconstruction. Materials and Methods Eighteen radiologists blinded to phantom and study design interpreted randomized image data sets that contained 36 spherical simulated liver lesions of three sizes and three attenuation differences (5-mm diameter: 12, 18, and 24 HU less than the 90-HU background attenuation of the simulated liver insert; 10- and 15-mm diameter: 6, 12, and 18 HU less than the 90-HU background attenuation) scanned with four discrete exposure settings and reconstructed by using FBP and sinogram-affirmed iterative reconstruction. Response assessment included region-level lesion presence or absence on a five-point diagnostic confidence scale. Statistical evaluation included multireader multicase receiver operating characteristic curve analysis, with nonparametric methods and noninferiority analysis at a margin of -0.10. Results Pooled accuracy at 75% exposure for both FBP and sinogram-affirmed iterative reconstruction was noninferior to 100% exposure (P = .002 and P < .001, respectively). Subsequent exposure reductions resulted in a significant decrease in accuracy. When the smallest (5-mm-diameter) lesions were excluded from analysis, sinogram-affirmed iterative reconstruction was superior to FBP at 100% exposure (P = .011), and sinogram-affirmed iterative reconstruction at 25% and 50% exposure reduction was noninferior to FBP at 100% exposure (P ≤ .013). Reader confidence was greater with sinogram-affirmed iterative reconstruction than with FBP for 10- and 15-mm lesions (2.94 vs 2.76 and 3.62 vs 3.52, respectively). Conclusion In this low-contrast low-attenuation liver lesion model, a 25% exposure reduction maintained noninferior diagnostic accuracy. However, detection was inferior with each subsequent exposure reduction, regardless of reconstruction method. Sinogram-affirmed iterative reconstruction and FBP performed equally well at modest exposure reduction (25%-50%). Readers had higher confidence levels with sinogram-affirmed iterative reconstruction for the 10- and 15-mm lesions. © RSNA, 2014 Online supplemental material is available for this article.

Cardiac telemedicine brings hope in Cameroon

Cardiac telemedicine brings hope in Cameroon


The incidence of heart disease is rising in many low- and middle-income countries around the world due to wealthier lifestyles and greater longevity. Cameroon is no exception. According to Cameroon’s Society of Cardiologists, some 30 per cent of the country’s 22 million people suffer from high blood pressure, which is one of the key contributing factors to heart disease. Yet there are fewer than 50 heart specialists, most of whom are based in the cities of Douala and Yaoundé, leaving rural areas with virtually no cardiac care.

Zang’s patented touchscreen Cardio Pad could change that. He has invented what is believed to be Africa’s first medical tablet, which will allow health-care workers in rural areas to send the results of cardiac tests to heart specialists via a mobile-phone connection.
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