EVALUATION OF SMALL ANIMAL IMAGING UNDER DIFFERENT SCAN CONDITIONS

To evaluae small animal imaging with individual different high voltage, filter thickness and tube current, an animal X-ray micro-computed tomography （micro-CT） system based on panel detector is developed and a rat is scanned by using the system with individual high voltage, tube current, filter thickness, and exposure time. A model is presented based on the Monte Carlo code PENELOPE for generating the X-ray spectra of X-ray tube used in the micro-CT system. A platform developed based on Matlab allows for calculating beam quality parameters, including the average energy of X-ray beam, the change of transmition rate and the input X-ray fluence. The factors affecting the signal difference to noise ratio （SDNR） of micro-CT are investigated and the relationship between SDNR and scan combinations is analyzed. A series of tools and methods are developed for small animal imaging and imaging performance evaluation in the field of small animal imaging.

Recent developments of fluorescence imaging technology in the second near-infrared window

Background:Fluorescence bio-imaging in the second near-infrared window(NIR-II FL,1000-1700nm)has great potential in clinical theranostics,which is of great importance providing precise locations of lesions and molecular dynamic actions simultaneously in a single nanoprobe.Methods:T here has been an upsurge of multidisciplinary research focusing on developing functional types of inorganic and organic nanoprobes that can be used for NIR-II FL with the high spatiotemporal resolution,deep tissue penetration,and negligible auto-fluorescence.Results:In this mini-review,we summarize recent progress in inorganic/organic NIR-II FL nanoprobes.We introduce the design and properties of inorganic and organic nanoprobes,in the order of single-walled carbon nanotubes,quantum dots,rare-earth-doped nanoparticles,metal nanoclusters and organic fluorophores,expect to realize precise diagnosis and efficient image-guided therapy.Conclusion:Meanwhile,to elucidate the problems and perspectives,we aim to offer diverse biological applications of inorganic/organic NIR-II FL nanoprobes and accelerate the clinical transformation progress.

Rare monolocular intrahepatic biliary cystadenoma: A case report

BACKGROUND Intrahepatic biliary cystadenoma(IBC)is a rare benign hepatic tumor that is often misdiagnosed as other hepatic cystic diseases.Therefore,imaging examinations are required for preoperative diagnosis.Contrast-enhanced ultrasound(CEUS)has gained increasing popularity as an emerging imaging modality and it is considered the primary method for screening IBC because of its specificity of performance.We describe an unusual case of monolocular IBC and emphasize the performance of CEUS.CASE SUMMARY A 45-year-old man complained of epigastric pain lasting 1 wk.He had no medical history of hepatitis,liver cirrhosis or parasitization.Physical examination revealed a mass of approximately 6 cm in size in the upper abdomen below the subxiphoid process.Tumor marker tests found elevated CA19-9 levels(119.3 U/mL),but other laboratory tests were unremarkable.Ultrasound and computerized tomography revealed a round thick-walled mass measuring 83 mm×68 mm located in the left lateral lobe of the liver that lacked internal septations and manifested as a monolocular cystic structure.CEUS demonstrated that in the arterial phase,the anechoic area manifested as a peripheral ring with homogeneous enhancement.The central part presented with no enhancement.During the portal phase,the enhanced portion began to subside but was still above the surrounding liver tissue.The patient underwent left partial liver lobectomy and recovered well without tumor recurrence or metastasis.Eventually,the results of pathological examination confirmed IBC.CONCLUSION A few IBC cases present with monolocular characteristics,and the lack of intracystic septa in imaging performance cannot exclude IBC.

Performance assessment of Cs I(T1) screens on various substrates for X-ray imaging

Thallium-doped cesium iodide（Cs I（Tl）） screens are widely used in X-ray imaging devices because of the columnar structure of the Cs I（Tl） layer, but few reports focus on the optical role of the substrate in the screen system.In this paper, four substrates including fused silica（Si O2）, silver-film coated Si O2, graphite（C） and fiber optic plate（FOP） are used to fabricate Cs I（Tl） screens by thermal evaporation. Their imaging performance is evaluated by relative light output（RLO）, modulation transfer function（MTF）, normalized noise power spectrum（NNPS） and noise equivalent quanta（NEQ）. The results reveal that although Cs I（Tl） film on graphite plate yields images with the lowest light output, it presents relatively higher spatial resolution and better signal-to-noise characteristics.However, films on Si O2 plate obtain low MTF but high NNPS curves, whether they are coated with silver film or not.Furthermore, scintillation screens on FOP have bright images with low NNPS and high NEQ, but have the lowest MTF. By controlling the substrate optical features, Cs I（Tl） films can be tailored to suit a given application.

Performance analysis of ghost imaging lidar in background light environment

The effect of background light on the imaging quality of three typical ghost imaging(GI) lidar systems(namely narrow pulsed GI lidar, heterodyne GI lidar, and pulse-compression GI lidar via coherent detection) is investigated. By computing the signal-to-noise ratio(SNR) of fluctuation-correlation GI, our analytical results, which are backed up by numerical simulations, demonstrate that pulse-compression GI lidar via coherent detection has the strongest capacity against background light, whereas the reconstruction quality of narrow pulsed GI lidar is the most vulnerable to background light. The relationship between the peak SNR of the reconstruction image andσ(namely, the signal power to background power ratio) for the three GI lidar systems is also presented, and theresults accord with the curve of SNR-σ.

Near infrared molybdenum oxide quantum dots with high photoluminescence and photothermal performance

The synthesized near infrared molybdenum oxide quantum dots perform excellent red fluorescence imaging performance and photothermal performance,which have 600,650 and 700 nm three unique peaks excited at 540 nm,with a high quantum yield around 20%.Meanwhile,with 808 nm NIR laser excitation,10 mg/mL modified Molybdenum oxide quantum dots can increase temperature up to 72.2℃within 150 s and 77.7℃within 270 s,respectively.