Statistical parametric mapping demonstrates asymmetric uptake with Tc-99m ECD and Tc-99m HMPAO SPECT in normal brain.
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ABSTRACT:
SUBMITTER: Brinkmann BH
PROVIDER: S-EPMC3323300 | biostudies-other | 2012 Jan
REPOSITORIES: biostudies-other
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Project description:To prevent and treat Parkinson's disease in its early stages, it is essential to be able to detect the degree of early dopaminergic neuron degeneration. Dopamine transporters (DAT) in the striatum regulate synaptic dopamine levels, and striatal 99mTc-TRODAT-1 single-photon emission computed tomography (-SPECT) imaging is a marker for presynaptic neuronal degeneration. However, the association between the degree of dopaminergic degeneration and in vivo 99mTc-TRODAT-1 SPECT imaging is unknown. Therefore, this study investigated the association between the degree of 6-hydroxydopamine (6-OHDA)-induced dopaminergic degeneration and DAT imaging using 99mTc-TRODAT-1 SPECT in rats. Different degrees of nigrostriatal dopamine depletion were generated by injecting different doses of 6-OHDA (2, 4, and 8 μg) into the right medial forebrain bundle. The degree of nigrostriatal dopaminergic neuron degeneration was assessed by rotational behavior and immunohistochemical staining. The results showed that striatal 99mTc-TRODAT-1 binding was significantly diminished both in the ipsilateral and the contralateral sides in the 4 and 8 μg 6-OHDA groups, and that DAT 99mTc-TRODAT-1 binding in the ipsilateral striatum showed a high correlation to apomorphine-induced rotations at 8 weeks post-lesion (r = -0.887, P < 0.01). There were significant correlations between DAT 99mTc-TRODAT-1 binding in the ipsilateral striatum and the amount of tyrosine hydroxylase immunoreactive neurons in the ipsilateral substantia nigra in the 2, 4, and 8 μg 6-OHDA groups at 8 weeks post-lesion (r = 0.899, P < 0.01). These findings indicate that striatal DAT imaging using 99mTc-TRODAT-1 is a useful technique for evaluating the severity of dopaminergic degeneration.
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Project description:PurposeInvestigate the impact of acquisition time and reconstruction parameters on single-photon emission computed tomography/computed tomography (SPECT/CT) image quality with the ultimate aim of finding the shortest possible acquisition time for clinical whole-body SPECT/CT (WB-SPECT/CT) while maintaining image quality METHODS: The National Electrical Manufacturers Association (NEMA) image quality measurements were performed on a SPECT/CT imaging system using a NEMA International Electrotechnical Commission (IEC) phantom with spherical inserts of varying diameter (10-37 mm), filled with 99m Tc in activity sphere-to-background concentration ratio of 8.5:1. A gated acquisition was acquired and binned data were summed to simulate acquisitions of 15, 8, and 3 s per projection angle. Images were reconstructed on a Hermes (HERMES Medical Solutions AB, Stockholm, Sweden) workstation using eight subsets and between 4 and 24 iterations of the three-dimensional (3D) ordered subset expectation maximization (OSEM) algorithm. Reconstructed images were post-smoothed with 3D Gaussian filter ranging from 0 to 12 mm full-width at half maximum (FWHM). Contrast recovery, background variability, and contrast-to-noise ratio were evaluated RESULTS: As expected, the spheres were more clearly defined as acquisition time and count statistics improved. The optimal iteration number and Gaussian filter were determined from the contrast recovery convergence and level of noise. Convergence of contrast recovery was observed at eight iterations while 12 iterations yielded stabilized values at all acquisition times. In addition, it was observed that applying 3D Gaussian filter of 8-12 mm FWHM suppressed the noise and mitigated Gibbs artifacts. Background variability was larger for small spheres than larger spheres and the noise decreased when acquisition time became longer. A contrast-to-noise ratio >5 was reached for the two smallest spheres of 10 and 13 mm at acquisition times of 8 s CONCLUSION: Optimized reconstruction parameters preserved image quality with reduce acquisition time in present study. This study suggests an optimal protocol for clinical 99m Tc SPECT/CT can be reached at 8 s per projection angle, with data reconstructed using 12 iterations and eight subset of the 3D OSEM algorithm and 8 mm Gaussian post-filter.
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Project description:Extradomain-B fibronectin (EDB-FN), an oncofetal isoform of FN, is a promising diagnostic and therapeutic target of tumors, including breast cancer. Many EDB-FN-targeted drugs have been developed and have shown therapeutic effects in clinical trials. Molecular imaging to visualize EDB-FN-positive cancers may help select the right patients who will be benefit from EDB-FN-targeted therapy. Although a few EDB-FN-targeted imaging probes have been developed, the complicated manufacturing procedure and expensive material and equipment required limit their application for large-scale screening of EDB-FN-positive cancer patients. Thus, more simple and economic EDB-FN-targeted imaging probes are still urgently needed. Previously, we have identified a breast cancer-targeted peptide, CTVRTSADC. Coincidently, it was later identified as an EDB-FN-targeted peptide and named ZD2. In this study, we found a positive correlation between the binding activity of the ZD2 phage and the expression level of EDB-FN in breast cancer cells. Moreover, we observed the colocalization of the ZD2 peptide with EDB-FN in breast cancer cells. Furthermore, in vivo tumor targeting of the ZD2 phage, near-infrared fluorescence imaging, and flow cytometry showed tumor-specific homing of the ZD2 peptide in mice bearing EDB-FN-positive breast cancers. Importantly, on the basis of this EDB-FN-targeted ZD2 peptide, we developed a kit-formulated probe, 99mTc-HYNIC-ZD2, for single-photon-emission computed tomography (SPECT) imaging of breast cancer. The high tumor uptake of 99mTc-HYNIC-ZD2 demonstrated its feasibility for use in visualizing EDB-FN-positive breast cancers in vivo. This kit-formulated EDB-FN-targeted SPECT probe has potential clinical applications for precision screening of EDB-FN-positive cancer patients who may benefit from EDB-FN-targeted therapy.
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Project description:BackgroundIn [99mTc]Tc-DPD scintigraphy for myocardial ATTR amyloidosis, planar images 3 hour p.i. and SPECT/CT acquisition in L-mode are recommended. This study investigated if earlier planar images (1 hour p.i.) are beneficial and if SPECT/CT acquisition should be preferred in H-mode (180° detector angle) or L-mode (90°).MethodsIn SPECT/CT phantom measurements (NaI cameras, N = 2; CZT, N = 1), peak contrast recovery (CRpeak) was derived from sphere inserts or myocardial insert (cardiac phantom; signal-to-background ratio [SBR], 10:1 or 5:1). In 25 positive and 38 negative patients (reference: endomyocardial biopsy or clinical diagnosis), Perugini scores and heart-to-contralateral (H/CL) count ratios were derived from planar images 1 hour and 3 hour p.i.ResultsIn phantom measurements, accuracy of myocardial CRpeak at SBR 10:1 (H-mode, 0.95-0.99) and reproducibility at 5:1 (H-mode, 1.02-1.14) was comparable for H-mode and L-mode. However, L-mode showed higher variability of background counts and sphere CRpeak throughout the field of view than H-mode. In patients, sensitivity/specificity were ≥ 95% for H/CL ratios at both time points and visual scoring 3 hour. At 1 hour, visual scores showed specificity of 89% and reduced reader's confidence.ConclusionsEarly DPD images provided no additional value for visual scoring or H/CL ratios. In SPECT/CT, H-mode is preferred over L-mode, especially if quantification is applied apart from the myocardium.
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