Post traumatic brain perfusion SPECT analysis using reconstructed ROI maps of radioactive microsphere derived cerebral blood flow and statistical parametric mapping

<p>Abstract</p> <p>Background</p> <p>Assessment of cerebral blood flow (CBF) by SPECT could be important in the management of patients with severe traumatic brain injury (TBI) because changes in regional CBF can affect outcome by promoting edema formation and intracranial pressure elevation (with cerebral hyperemia), or by causing secondary ischemic injury including post-traumatic stroke. The purpose of this study was to establish an improved method for evaluating regional CBF changes after TBI in piglets.</p> <p>Methods</p> <p>The focal effects of moderate traumatic brain injury (TBI) on cerebral blood flow (CBF) by SPECT cerebral blood perfusion (CBP) imaging in an animal model were investigated by parallelized statistical techniques. Regional CBF was measured by radioactive microspheres and by SPECT 2 hours after injury in sham-operated piglets versus those receiving severe TBI by fluid-percussion injury to the left parietal lobe. Qualitative SPECT CBP accuracy was assessed against reference radioactive microsphere regional CBF measurements by map reconstruction, registration and smoothing. Cerebral hypoperfusion in the test group was identified at the voxel level using statistical parametric mapping (SPM).</p> <p>Results</p> <p>A significant area of hypoperfusion (P < 0.01) was found as a response to the TBI. Statistical mapping of the reference microsphere CBF data confirms a focal decrease found with SPECT and SPM.</p> <p>Conclusion</p> <p>The suitability of SPM for application to the experimental model and ability to provide insight into CBF changes in response to traumatic injury was validated by the SPECT SPM result of a decrease in CBP at the left parietal region injury area of the test group. Further study and correlation of this characteristic lesion with long-term outcomes and auxiliary diagnostic modalities is critical to developing more effective critical care treatment guidelines and automated medical imaging processing techniques.</p

Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study

A41 Use of SMS texts for facilitating access to online alcohol interventions: a feasibility study In: Addiction Science & Clinical Practice 2017, 12(Suppl 1): A4

An algorithm for PET tumor volume and activity quantification: Without specifying camera's point spread function (PSF)

Purpose: The authors have developed an algorithm for segmentation and removal of the partial volume effect (PVE) of tumors in positron emission tomography (PET) images. The algorithm accurately measures functional volume (FV) and activity concentration (AC) of tumors independent of the camera's full width half maximum (FWHM). Methods: A novel iterative histogram thresholding (HT) algorithm is developed to segment the tumors in PET images, which have low resolution and suffer from inherent noise in the image. The algorithm is initiated by manually drawing a region of interest (ROI). The segmented tumors are subjected to the iterative deconvolution thresholding segmentation (IDTS) algorithm, where the Van-Cittert's method of deconvolution is used for correcting PVE. The IDTS algorithm is fully automated and accurately measures the FV and AC, and stops once it reaches convergence. The convergence criteria or stopping conditions are developed in such a way that the algorithm does not rely on estimating the FWHM of the point spread function (PSF) to perform the deconvolution process. The algorithm described here was tested in phantom studies, where hollow spheres (0.5–16 ml) were used to represent tumors with a homogeneous activity distribution, and an irregular shaped volume was used to represent a tumor with a heterogeneous activity distribution. The phantom studies were performed with different signal to background ratios (SBR) and with different acquisition times (1 min, 3 min, and 5 min). The parameters in the algorithm were also changed (FWHM and matrix size of the Gaussian function) to check the accuracy of the algorithm. Simulated data were also used to test the algorithm with tumors having heterogeneous activity distribution. Results: The results show that changing the size and shape of the ROI during initiation of the algorithm had no significant impact on the FV. An average FV overestimation of 30% and an average AC underestimation of 35% were observed for the smallest tumor (0.5 ml) over the entire range of noise and SBR level. The difference in average FV and AC estimations from the actual volumes were less than 5% as the tumor size increased to 16 ml. For tumors with heterogeneous activity profile, the overall volume error was less than 10%. The average overestimation of FV was less than 10% and classification error was around 11%. Conclusions: The algorithm developed herein was extensively tested and is not dependent on accurately quantifying the camera's PSF. This feature demonstrates the robustness of the algorithm and enables it to be applied on a wide range of noise and SBR within an image. The ultimate goal of the algorithm is to be able to be operated independent of the camera type used and the reconstruction algorithm deployed

Chemotherapy-induced changes in cardiac capillary permeability measured by fluorescent multiple indicator dilution.

Anthracyclines cause severe irreversible cardiac toxicity. The study of changes in cardiac permeability with chemotherapy could enhance the understanding of mechanisms behind cardiac damage, and provide useful information to evaluate anthracycline cardiotoxicity. Thirty-six rats (12 Sprague-Dawley, 12 Wistar, 12 Fischer-344) were randomly assigned to control (n = 21) or doxorubicin (n = 15), and injected i.p. with a cumulative dose of 18 mg/kg doxorubicin in saline (vehicle) or vehicle alone over 12 days. Echocardiography was performed at baseline and on day 11. An isolated heart experiment was done on day 12 to obtain perfused heart pressure values, and to measure cardiac capillary permeability using a Texas Red/sodium fluorescein multiple indicator dilution method. Control animals had significantly lower average permeability-surface-area-products (0.035 ± 0.013 cm(3)/s) than doxorubicin animals (0.066 ± 0.023 cm(3)/s), PSP ± SD, p \u3c 0.001. These permeability changes correlated with significant functional changes. There was a significant decline in cardiac function with a deleterious effect of chemotherapy on fractional shortening (p \u3c 0.001), left ventricular developed pressure (p \u3c 0.001), contractility (p \u3c 0.001), and relaxation (p = 0.02). Based on our results, cardiac capillary permeability changes can be detected after in vivo chemotherapy treatment using our fluorescent multiple indicator dilution technique, and may provide valuable information in evaluating cardiotoxicity of novel drugs