Vibrational Photoacoustic Tomography (VPAT) is an emerging imaging modality that utilizes pulsed laser light to induce acoustic waves and obtain tissue specific compositional information. When used in combination with ultrasound, VPAT has the potential to identify the location, size, and distribution of lipids
in vivo
. In our study, we hypothesized that VPAT can be used to distinguish perivascular aortic fat accumulation between apolipoprotein E-deficient (apoE
-/-
) and wild-type (WT) mice. A 40 MHz central frequency transducer (Vevo2100, VisualSonics) and a ND:YAG pulsed laser (NT352C, Ekspla) were used to simultaneously obtain both long axis
in vivo
B-mode and VPAT images of the infrarenal aorta in three apoE
-/-
(8.7±0 months old) and WT controls (2.9±0 months old) mice. Pulsed laser light was specifically tuned to 1100nm and 1210nm to image blood and lipid, respectively. We then measure perivascular lipid thickness in three distinct locations along the anterior wall of the aorta. These measurements were then averaged to obtain a final perivascular fat thickness score for both the apoE
-\-
and WT groups. We observed greater 1210 nm signal in apoE
-/-
(0.47±0.14 mm) mice versus WT mice (0.32±0.11 mm; p<0.05), suggesting that apoE
-/-
mice have greater perivascular lipid accumulation than WT controls. These findings are significant as they show that VPAT can be used to image and track lipid accumulation
in vivo
. Future work will focus on monitoring luminal plaque progression in atherosclerotic murine models, including hypercholesterolemic mice on a high fat diet or rodent models of severe carotid stenosis. If successful, VPAT has the potential to be used in the clinic to 1) study atherosclerosis plaque development, 2) evaluate the effectiveness of prospective therapeutics, and 3) improve the diagnosis of atherosclerosis or related vascular diseases.
In vivo evaluation of cerebral venous sinus morphology using pulsed-laser-diode-based desktop photoacoustic tomography system
