Current Molecular Imaging (Discontinued) - Volume 3, Issue 1, 2014

Background: Limited data are available in the literature comparing brain SPECT, PET and volumetric MRI in the same cohort of patients with Alzheimer’s disease. Objectives: The main goal was to show a correlation between two different functional imaging substrates, as determined by FDG-PET and SPECT, with structural MRI findings as defined by voxel-based volumetric measurements (VBM), in the same cohort of patients with AD. Methods: 20 patients (9 male) with confirmed clinical diagnosis of Alzheimer’s disease (AD) and mild dementia according to NINCDS/ADRDA and DSM-III-R criteria were selected to be included in the present study. Twenty normal elderly volunteers constituted the Control Group. The two groups were paired for age, sex and educational level (p>0.05). The same clinical protocol was applied in patients and controls. Brain SPECT, PET and MR were performed with an interval among them shorter than 4 weeks. Results: Reduced brain glucose metabolism (MRglc) by PET occurred predominantly in the posterior cingulum and precuneus, followed by bilateral posterior parietal, lower temporal and frontal cortices (p<0.001). Similar findings were shown on SPECT, albeit with lesser statistical significance compared to FDG-PET (Z score of 3.89 vs. 5.32). SPECT depicted subtle blood flow reduction in mesial temporal lobes on SPM, a finding not reproduced by PET. MRI showed significant atrophy in hippocampus and superior temporal cortex, bilaterally, but not in the posterior cingulate gyrus, parietal or frontal lobes. Conclusion: A not perfect correlation was seen among the findings seen on SPECT, PET and MRI in the same cohort of patients with AD, suggesting that structural and functional methods reveal distinct substrates of the disease.

Purpose: To investigate the association between changes on [18F] fluorodeoxyglucose positron emission tomography (FDG-PET) and clinical deterioration in patients with moderate Alzheimer’s disease (AD), findings of FDG-PET in the first and follow-up stages were compared using stereotactic extraction estimation (SEE) and three-dimensional stereotactic surface projection (3D-SSP). Methods and patients: Thirty consecutive patients with AD examined twice by FDG-PET were divided into two groups with improved or stable mini-mental state examination (MMSE) (SI group, 14 patients) and deteriorated MMSE (D group, 16 patients). Statistical analysis using SEE in 3D-SSP was used to investigate the changes in Z-score in the frontal, parietal, temporal, and occipital lobes, precuneus, and posterior cingulate cortex (PCC). Results: Changes in Z-scores in the PCC (p=0.0006) and temporal lobe (p=0.021) were significantly higher in the D group than in the SI group. Z-score was significantly higher in the left PCC compared to the right PCC (p=0.0097). Conclusions: SEE in 3D-SSP is the helpful method to detect the regional differences. Metabolic reduction on FDG-PET in the left PCC detected by SEE and 3D-SSP is associated with clinical deterioration in patients with moderate AD.

Both neuropsychiatric disorders and malignancies of central nervous system (CNS) represent a significant health burden and life-threatening diseases worldwide. Radiotracer-based neuroimaging is an attractive tool that permits the in vivo detection and characterization of metabolic and molecular processes which are fundamental elements for brain function, and improves the theranostics of brain diseases and disorders. In this review, we outlined the new development of molecular imaging probes for dopamine and serotonin systems in neuropsychiatry and boron neutron capture therapy (BNCT) for brain tumors in neuro-oncology with positron emission tomography (PET) and single-photon emission computed tomography (SPECT).

Vascular thrombosis is a crucial event and still cause of significant morbidity and mortality worldwide. Deep vein thrombosis with subsequent pulmonary embolism constitutes a frequent clinical event, while reliable detection, especially of small or old thrombi, still remains clinically challenging. Occlusion or thromboembolism in an arterial vessel may result in myocardial infarction or stroke, and early detection would be of enormous clinical interest. Noninvasive molecular imaging techniques, particularly targeting key structures of developing or established thrombosis, have demonstrated its ability to detect this pathology in different models of disease, and current research is heading towards clinical translation. In this article, recent developments and challenges of molecular imaging of vascular thrombosis involving magnetic resonance imaging, ultrasound and nuclear imaging techniques are reviewed.

The infection of a vascular prosthesis (VGI) is the most serious complication in prosthetic vascular reconstructive surgery, burdened by a high rate of mortality and morbidity. The treatment of a VGI, in most cases, consists of its surgical removal, and therefore an accurate diagnosis of the infection, is of paramount importance in clinical practice since false-positive results may lead to unnecessary major surgery whereas false-negative results are related with high-risk morbidity. Furthermore, early diagnosis of infection permits a wider range of therapeutic options and a less aggressive surgical approach. On the basis of the documents and abstracts published in the last 25 years, the authors analyze and discuss the contribution of nuclear medicine in the management of these infections, evaluating the reliability of scintigraphy with labeled leukocytes, other gamma-emitting radiopharmaceuticals, PET and PET / CT with 18F-Fluorodeoxiglucose.

Purpose: Cell surface antigens as biomarkers suggest high potential for early diagnosis in cancers. The scope of this study is to synthesize Gd3+ based silica nanoparticles that conjugate on monoclonal antibody C595 by a facile method in order to detect human prostate cancer cells. Method: In this study, monoclonal antibody C595, anti-MUC-1, was conjugated on Gd3+-based mesoporous silica nanospheres (MSN-Gd3+-C595) (71.1 nm) by utilizing N-5-Azido-2-nitrobenzoyloxy succinimide (ANB-NOS) cross linkers. This contrast agent was characterized using techniques such as nitrogen physisorption, thermogravimetric analysis, scanning and transmission electron microscopy, inductively coupled plasma atomic emission spectrometry (ICP-AES) and Dynamic Light Scattering (DLS). The relaxivities were determined using a 3 Tesla MRI scanner. The accurate and easily available in vitro assay based on MSN-Gd3+-C595 was applied to identify the cell surface antigen expression in the case of prostate cancer cells and the quantitative data were analyzed. Results: Results showed that N-5-Azido-2-nitrobenzoyloxysuccinimide cross-linkers were suitable for conjugation of C595 on the surface of mesoporous silica nanospheres. Protein measurement assay indicated that 8% antibodies were attached on the surface of mesoporous silica nanospheres and TGA and ICP-AES results demonstrated that 19 wt% Gd3+-DTTA were loaded into C595-MSN-Gd3+. Furthermore, the obtained data showed a powerful relaxations as well as selective MUC-1 antigen binding to the cell. Conclusion: Based on the results of the present study, MSN-Gd3+-C595 nanoprobe may be a potential prostate molecular imaging and may provide critical guideline in selecting these nanoparticles as an appropriate contrast agent for nanomedicine applications.

Apoptosis or genetically programmed cell death is a universal phenomenon involving many pathophysiological conditions. Externalization of phosphatidylserine from the inner leaflet to the outer leaflet of the cell membrane is an early event in the apoptotic cascade occurring before membrane blebbing and DNA fragmentation. Annexin A5, a 36 kDa endogenous protein, specifically binds to phosphatidylserine with a nanomolar affinity in presence of calcium ions. In molecular imaging, phosphatidylserine has been used as a molecular target for the imaging of apoptosis with 99mTc-annexin A5 as a molecular probe. In clinical research, recombinant human 99mTc-annexin A5 has been successfully used in phase I, II, III and IV trials for the non-invasive assessment of apoptotic reserve in vivo. In academic centers, annexin A5 imaging has also been the subject of theses including doctoral theses, master theses and memoire. This review highlights the large body corpus of literature on the radiolabeled annexin A5 imaging including publications on clinical trials and academic dissertations.

Burn wounds become colonized with bacteria during the course of recovery. In addition, there are some burn patients whose wounds do not heal for months. In the present study, we attempted to determine: 1. If seeding of a burn wound with Staphylococcus aureus would affect wound healing: and 2. If knocking out IL-6 and TNF, two cytokines commonly associated with burn injury, would alter burn wound healing. Using bioluminescent Staphylococcus aureus, there appeared to be no difference in the rate of wound healing between the inoculated burn wounds and the uninoculated burn wounds in the wild type mice. However, burn wounds on the Il-6 or TNF knockout mice did not heal as quickly as the wild type (WT mice). These data support the hypothesis that Staphylococcus aureus that colonize the wound may not alter burn wound healing. However, the present data suggest that Il-6 and TNF may play a role in burn wound healing.