Molecular Imaging最新文献

Spinal cord injury (SCI) leads to severe dysfunction below injured segment and poses a great pressure to the individual and society. In this study, we applied ¹⁸F-alfatide II positron emission tomography/computed tomography (PET/CT) to monitor angiogenesis in an SCI model after estrogen (E2) treatment, as well as to evaluate the prognosis in a noninvasive manner. The SCI model was established with male rats and the rats were randomly divided into E2-treated group (SCI + E2) and E2-untreated group (SCI). Sham group was also used as control (Sham). The angiogenesis after SCI was monitored by ¹⁸F-alfatide II PET/CT and verified by immunofluorescence of CD31 and CD61. We also evaluated the level of E2 and growth-associated protein 43 (GAP43) by enzyme-linked immunosorbent assay. Finally, Basso, Beattie, and Bresnahan (BBB) scores were determined to evaluate the exercise capacity of the rats in all 3 groups. Our results showed that the BBB score of SCI + E2 group was significantly different from that of SCI group (P < .05) and Sham group (P < .01). The uptake of ¹⁸F-alfatide II was positively correlated with the expression level of GAP43, both of which reached the peak at day 7 after injury. CD31 and CD61 immunostaining further verified increased angiogenesis in E2-treated SCI lesions. We concluded that ¹⁸F-alfatide II PET/CT can monitor the angiogenesis status after SCI in vivo and it may help clinician predict the progression of patients with SCI. This may benefit the study of vascular repair after SCI and provide a tool for evaluation of SCI treatment in clinical practices.

Purpose: Imaging is limited in the evaluation of bacterial infection. Direct imaging of in situ bacteria holds promise for noninvasive diagnosis. We investigated the ability of a bacterial thymidine kinase inhibitor ([¹²⁴I]FIAU) to image pulmonary and musculoskeletal infections.

Methods: Thirty-three patients were prospectively accrued: 16 with suspected musculoskeletal infection, 14 with suspected pulmonary infection, and 3 with known rheumatoid arthritis without infection. Thirty-one patients were imaged with [¹²⁴I]FIAU PET/CT and 28 with [¹⁸F]FDG PET/CT. Patient histories were reviewed by an experienced clinician with subspecialty training in infectious diseases and were determined to be positive, equivocal, or negative for infection.

Results: Sensitivity, specificity, positive-predictive value, negative-predictive value, and accuracy of [¹²⁴I]FIAU PET/CT for diagnosing infection were estimated as 7.7% to 25.0%, 0.0%, 50%, 0.0%, and 20.0% to 71.4% for musculoskeletal infections and incalculable-100.0%, 51.7% to 72.7%, 0.0% to 50.0%, 100.0%, and 57.1% to 78.6% for pulmonary infections, respectively. The parameters for [¹⁸F]FDG PET/CT were 75.0% to 92.3%, 0.0%, 23.1% to 92.3%, 0.0%, and 21.4% to 85.7%, respectively, for musculoskeletal infections and incalculable to 100.0%, 0.0%, 0.0% to 18.2%, incalculable, and 0.0% to 18.2% for pulmonary infections, respectively.

Conclusions: The high number of patients with equivocal clinical findings prevented definitive conclusions from being made regarding the diagnostic efficacy of [¹²⁴I]FIAU. Future studies using microbiology to rigorously define infection in patients and PET radiotracers optimized for image quality are needed.

Purinergic receptors play important roles in central nervous system (CNS). These receptors are involved in cellular neuroinflammatory responses that regulate functions of neurons, microglial and astrocytes. Based on their endogenous ligands, purinergic receptors are classified into P1 or adenosine, P2X and P2Y receptors. During brain injury or under pathological conditions, rapid diffusion of extracellular adenosine triphosphate (ATP) or uridine triphosphate (UTP) from the damaged cells, promote microglial activation that result in the changes in expression of several of these receptors in the brain. Imaging of the purinergic receptors with selective Positron Emission Tomography (PET) radioligands has advanced our understanding of the functional roles of some of these receptors in healthy and diseased brains. In this review, we have accumulated a list of currently available PET radioligands of the purinergic receptors that are used to elucidate the receptor functions and participations in CNS disorders. We have also reviewed receptors lacking radiotracer, laying the foundation for future discoveries of novel PET radioligands to reveal these receptors roles in CNS disorders.

Background: Near-infrared photoimmunotherapy (NIR-PIT) is a cancer therapy that causes an increase in tumor perfusion, a phenomenon termed the super-enhanced permeability and retention effect. Currently, in vivo treatment efficacy of NIR-PIT is observable days after treatment, but monitoring would be improved by more acute detection of intratumor change. Fluorescence imaging may detect increased tumor perfusion immediately after treatment.

Methods: In the first experiment, athymic nude mouse models bearing unilateral subcutaneous flank tumors were treated with either NIR-PIT or laser therapy only. In the second experiment, mice bearing bilateral flank tumors were treated with NIR-PIT only on the left-sided tumor. In both groups, immediately after treatment, indocyanine green was injected at different doses intravenously, and mice were monitored with the Shimadzu LIGHTVISION fluorescence imaging system for 1 hour.

Results: Tumor-to-background ratio of fluorescence intensity increased over the 60 minutes of monitoring in treated mice but did not vary significantly in control mice. Tumor-to-background ratio was highest in the 1 mg kg^-1 and 0.3 mg kg^-1 doses. In mice with bilateral tumors, tumor-to-untreated tumor ratio increased similarly.

Conclusions: Acute changes in tumor perfusion after NIR-PIT can be detected by real-time fluorescence imaging.