Accurate characterization of carotid plaque composition is essential to identify vulnerable plaque that often leads to stroke. Photoacoustic imaging, which combines optical absorption contrast with ultrasonic imaging depth, shows promise for quantitative examination of carotid plaque. However, unknown light fluence in the tissue makes quantitative photoacoustic imaging challenging. We propose utilizing a known chromophore as a light fluence marker. The feasibility of the approach was tested using simulations on digital phantoms and experiments using tissue-mimicking phantoms. The results show agreement with the actual concentrations, supporting our hypothesis. We intend to extend the approach to ex vivo plaque imaging.
Absolute myocardial perfusion imaging (MPI) can be beneficial in the diagnosis and prognosis of patients with coronary artery disease. However, validation and standardization of perfusion estimates across centers is needed to ensure safe and adequate integration into clinical routine. MPI phantoms can contribute to this clinical need as these models can provide ground truth evaluation of absolute MPI in a simplified, though controlled setup. This work presents verification of phantom design choices, including the justification for using sorbents in mimicking contrast kinetics (i.e., tracer uptake and retention). Moreover, we compare preliminary phantom results obtained with SPECT-MPI with a patient example. Finally, we applied a general two-tissue compartment model to describe the obtained phantom time activity curve data. These evaluation steps support shaping of a suitable verification and validation strategy for the multimodal myocardial perfusion phantom design and realization.
Institutional diagnostic workflows regarding coronary artery disease (CAD) may differ greatly. Myocardial perfusion imaging (MPI) is a commonly used diagnostic method in CAD, whereby multiple modalities are deployed to assess relative or absolute myocardial blood flow (MBF) (e.g. with SPECT, PET, MR, CT, or combinations). In line with proper clinical decision-making, it is essential to assess institutional MPI test validity by confronting MBF assessment to a ground truth. Our research focuses on developing such validation instrument/method for MPI by means of simulating controlled myocardial perfusion in a phantom flow setup. A first step was made in the process of method development and validation by specifying basic requirements for the phantom flow setup. First tests in CT-MPI were aimed to gain experience in clinical testing, to verify to which extent the set requirements are met, and to evaluate the steps needed to further improve accuracy and reproducibility of measurements. The myocardium was simulated as a static cylinder and placed in a controllable pulsatile flow circuit whereby using flow sensors as reference. First flow experiments were performed for different stroke volumes (20-35 mL/stroke). After contrast injection, dynamic MPI-CT scans (SOMATOM Force, Siemens) were obtained to investigate the relation between first-pass measured and computed flow. We observed a moderate correlation; hence, the required accuracy and reproducibility levels were not met. However, we have gained new insights in factors regarding the measurement setup and MBF computation process that might affect instrument validation, which we will incorporate in future flow setup design and testing.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.