Preliminary Imaging Research Articles

3D Ultrasound Imaging of Residual Limbs With Camera-Based Motion Compensation.

Ultrasound is a cost-effective, readily available, and non-ionizing modality for musculoskeletal imaging. Though some research groups have pursued methods that involve submerging the transducer and imaged body segment into a water bath, many limitations remain in regards to acquiring an unloaded volumetric image of an entire human limb in a fast, safe, and adequately accurate manner. A 3D dataset of a limb is useful in several rehabilitative applications including biomechanical modeling of soft tissue, prosthetic socket design, monitoring muscle condition and disease progression, bone health, and orthopedic surgery. This paper builds on previous work from our group and presents the design, prototyping, and preliminary testing of a novel multi-modal imaging system for rapidly acquiring volumetric ultrasound imagery of human limbs, with a particular focus on residual limbs for improved prosthesis design. Our system employs a mechanized water tank setup to scan a limb with a clinical ultrasound transducer and 3D optical imagery to track motion during a scan. The iterative closest point algorithm is utilized to compensate for motion and stitch the images into a final dataset. The results show preliminary 2D and 3D imaging of both a tissue-mimicking phantom and residual limbs. A volumetric error compares the ultrasound image data obtained to a previous MRI method. The results indicate potential for future clinical implementation. Concepts presented in this paper could reasonably transfer to other imaging applications such as acoustic tomography, where motion artifact may distort image reconstruction.

CMKLR1-targeting peptide tracers for PET/MR imaging of breast cancer.

Background: Molecular targeting remains to be a promising approach in oncology. Overexpression of G protein-coupled receptors (GPCRs) in human cancer is offering a powerful opportunity for tumor-selective imaging and treatment employing nuclear medicine. We utilized novel chemerin-based peptide conjugates for chemokine-like receptor 1 (CMKLR1) targeting in a breast cancer xenograft model.Methods: By conjugation with the chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), we obtained a family of five highly specific, high-affinity tracers for hybrid positron emission tomography/magnetic resonance (PET/MR) imaging. A xenograft model with target-positive DU4475 and negative A549 tumors in immunodeficient nude mice enabled CMKLR1-specific imaging in vivo. We acquired small animal PET/MR images, assessed biodistribution by ex vivo measurements and investigated the tracer specificity by blocking experiments.Results: Five CMKLR1-targeting peptide tracers demonstrated high biological activity and affinity in vitro with EC50 and IC50 values below 2 nM. Our target-positive (DU4475) and target-negative (A549) xenograft model could be validated by ex vivo analysis of CMKLR1 expression and binding. After preliminary PET imaging, the three most promising tracers [68Ga]Ga-DOTA-AHX-CG34, [68Ga]Ga-DOTA-KCap-CG34 and [68Ga]Ga-DOTA-ADX-CG34 with best tumor uptake were further analyzed. Hybrid PET/MR imaging along with concomitant biodistribution studies revealed distinct CMKLR1-specific uptake (5.1% IA/g, 3.3% IA/g and 6.2% IA/g 1 h post-injection) of our targeted tracers in DU4475 tumor tissue. In addition, tumor uptake was blocked by excess of unlabeled peptide (6.4-fold, 5.5-fold and 3.4-fold 1 h post-injection), further confirming CMKLR1 specificity. Out of five tracers, we identified these three tracers with moderate, balanced hydrophilicity to be the most potent in receptor-mediated tumor targeting.Conclusion: We demonstrated the applicability of 68Ga-labeled peptide tracers by visualizing CMKLR1-positive breast cancer xenografts in PET/MR imaging, paving the way for developing them into theranostics for tumor treatment.

Synthesis and Initial In Vivo Evaluation of [11C]AZ683-A Novel PET Radiotracer for Colony Stimulating Factor 1 Receptor (CSF1R).

Positron emission tomography (PET) imaging of Colony Stimulating Factor 1 Receptor (CSF1R) is a new strategy for quantifying both neuroinflammation and inflammation in the periphery since CSF1R is expressed on microglia and macrophages. AZ683 has high affinity for CSF1R (Ki = 8 nM; IC50 = 6 nM) and >250-fold selectivity over 95 other kinases. In this paper, we report the radiosynthesis of [11C]AZ683 and initial evaluation of its use in CSF1R PET. [11C]AZ683 was synthesized by 11C-methylation of the desmethyl precursor with [11C]MeOTf in 3.0% non-corrected activity yield (based upon [11C]MeOTf), >99% radiochemical purity and high molar activity. Preliminary PET imaging with [11C]AZ683 revealed low brain uptake in rodents and nonhuman primates, suggesting that imaging neuroinflammation could be challenging but that the radiopharmaceutical could still be useful for peripheral imaging of inflammation.

Role of Abdominal Ultrasonography as a Preliminary Imaging Technique in the Assessment of Female Pelvic Pathologies

Role of Abdominal Ultrasonography as a Preliminary Imaging Technique in the Assessment of Female Pelvic Pathologies

Dissociation dynamics of the water dication following one-photon double ionization. I. Theory

The measurement of the triple differential cross section in the body frame for double photoionization of a molecule can be made in principle by detecting the ionic fragments and the two photoelectrons in coincidence---but only if the dynamics and geometry of dissociation of the doubly charged molecular ion are known. A classical trajectory study of the nine lowest states of the water dication is presented using high quality ab initio potential-energy surfaces. Sampling from a semiclassical initial distribution of positions and momenta is used to approximate ionization from the Frank-Condon region of the ground vibrational state of neutral ${\mathrm{H}}_{2}\mathrm{O}$. Excellent agreement in comparison with preliminary experimental momentum imaging measurements of double photoionization of water show that eight dication states can be unambiguously identified in the experiment with the aid of theory. The theoretical trajectory results allow body frame measurements of double photoionization to yield all eight states even though the usual assumption of direct dissociation, the ``axial recoil'' approximation, breaks down for three of the dication electronic states seen in the experiment.

Filling Tricompartmental Ligands with GdIII and ZnII Ions: Some Structural and MRI Studies

Here we report the synthesis and characterization of a mononuclear gadolinium complex (Gd) and two heteronuclear Zn-Gd complexes (ZnGd and Zn2Gd), which contain two similar three-armed ligands that display an external compartment suitable for lanthanoid ions, and two internal compartments adequate for zinc (II) ions [H3L′ = (2-(3-formyl-2-hydroxy-5-methyl phenyl)-1,3-bis[4 -(3-formyl-2-hydroxy-5-methylphenyl)-3-azabut-3-enyl]-1,3-imidazolidine; H3L = 2-(5-bromo-2-hydroxy-3-methoxyphenyl)-1,3-bis[4-(5-bromo-2-hydroxy-3-methoxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine]. The synthetic methods used were varied, but the use of a metalloligand, [Zn2(L)AcO], as starting material was the key factor to obtain the heterotrinuclear complex Zn2Gd. The structure of the precursor dinuclear zinc complex is mostly preserved in this complex, since it is based on a compact [Zn2Ln(L)(OH)(H2O)]3+ residue, with a µ3-OH bridge between the three metal centers, which are almost forming an isosceles triangle. The asymmetric spatial arrangement of other ancillary ligands leads to chirality, what contrasts with the totally symmetric mononuclear gadolinium complex Gd. These features were confirmed by the crystal structures of both complexes. Despite the presence of the bulky compartmental Schiff base ligand, the chiral heterotrinuclear complex forms an intricate network which is predominately expanded in two dimensions, through varied H-bonds that connect not only the ancillary ligands, but also the nitrate counterions and some solvated molecules. In addition, some preliminary magnetic resonance imaging (MRI) studies have been made to determine the relaxivities of the three gadolinium complexes, with apparently improved T1 and T2 relaxivities with increasing zinc nuclearity, since both transversal and longitudinal relaxivities appear to enhance in the sequence Gd < ZnGd < Zn2Gd.

Histologic validation of ICDAS-II and polarization sensitive optical coherence tomography to detect smooth surface early carious lesions.

This in vitro study aimed to histologically validate and compare the methods for detection of smooth surface early carious lesions (ECLs) that is, International caries detection and assessment system for the smooth surface (ICDAS-II-SSC), Polarization sensitive optical coherence tomography (PS-OCT), and radiography. PS-OCT images for scores 0-3 of ICDAS-II-SSC were standardized according to ECLs' depth. Preliminary PS-OCT images for ICDAS-II-SSC score-2 of pigmented ECLs showed reduced lesion depth and therefore were dichotomized into scores 2 and 2p for white and pigmented lesions (ICDAS-II-SSCm). ECLs on one hundred freshly extracted teeth were scored by three examiners for ICDAS-II-SSCm, PS-OCT, radiography, and histology. Compared to histology, ICDAS-II-SSCm showed a strong positive correlation followed by PS-OCT and radiographic evaluation. ICDAS-II-SSCm had a strong positive correlation with PS-OCT, while both variables had a weak positive correlation with radiography. PS-OCT detected the activity of ECLs by directly relating the image depth of ECLs to their mineral volume content. The current scope of ICDAS-II should be reviewed since the pigmentation can be misinterpreted as an active lesion. Till then, ICDAS-II-SSC is an effective visual method for early caries detection. PS-OCT has the potential to become a probe with the proper algorithm for diagnostic purposes.

Bimodal reflectance and fluorescence multispectral endoscopy based on spectrally resolving detector arrays.

.Emerging clinical interest in combining standard white light endoscopy with targeted near-infrared (NIR) fluorescent contrast agents for improved early cancer detection has created demand for multimodal imaging endoscopes. We used two spectrally resolving detector arrays (SRDAs) to realize a bimodal endoscope capable of simultaneous reflectance-based imaging in the visible spectral region and multiplexed fluorescence-based imaging in the NIR. The visible SRDA was composed of 16 spectral bands, with peak wavelengths in the range of 463 to 648 nm and full-width at half-maximum (FWHM) between 9 and 26 nm. The NIR SRDA was composed of 25 spectral bands, with peak wavelengths in the range 659 to 891 nm and FWHM 7 to 15 nm. The spectral endoscope design was based on a “babyscope” model using a commercially available imaging fiber bundle. We developed a spectral transmission model to select optical components and provide reference endmembers for linear spectral unmixing of the recorded image data. The technical characterization of the spectral endoscope is presented, including evaluation of the angular field-of-view, barrel distortion, spatial resolution and spectral fidelity, which showed encouraging performance. An agarose phantom containing oxygenated and deoxygenated blood with three fluorescent dyes was then imaged. After spectral unmixing, the different chemical components of the phantom could be successfully identified via majority decision with high signal-to-background ratio (). Imaging performance was further assessed in an ex vivo porcine esophagus model. Our preliminary imaging results demonstrate the capability to simultaneously resolve multiple biological components using a compact spectral endoscopy system.

Radiosynthesis, biological evaluation and preliminary microPET study of 18F-labeled 5-resorcinolic triazolone derivative based on ganetespib targeting HSP90

Heat-shock protein 90 (HSP90) is a molecular chaperone that activates oncogenic transformation in several solid tumors, including lung and breast cancers. Ganetespib, a most promising candidate among several HSP90 inhibitors under clinical trials, has entered Phase III clinical trials for cancer therapy. Despite numerous evidences validating HSP90 as a target of anticancer, there are few studies on PET agents targeting oncogenic HSP90. In this study, we synthesized and biologically evaluated a novel 18F-labeled 5-resorcinolic triazolone derivative (1, [18F]PTP-Ganetespib) based on ganetespib. [18F]PTP-Ganetespib was labeled by click chemistry of Ganetespib-PEG-Alkyne (10) and [18F]PEG-N3 (11) with 37.3 ± 5.11% of radiochemical yield and 99.7 ± 0.09% of radiochemical purity. [18F]PTP-Ganetespib showed proper LogP (0.96 ± 0.06) and good stability in human serum over 97% for 2 h. [18F]PTP-Ganetespib showed high uptakes in breast cancer cells containing triple negative breast cancer (TNBC) MDA-MB-231 and Her2-negative MCF-7 cells, which are target breast cancer cell lines of HSP90 inhibitor, ganetespib, as an anticancer. Blocking of HSP90 by the pretreatment of ganetespib exhibited significantly decreased accumulation of [18F]PTP-Ganetespib in MDA-MB-231 and MCF-7 cells, indicating the specific binding of [18F]PTP-Ganetespib to MDA-MB-231 and MCF-7 cells with high HSP90 expression. In the biodistribution and microPET imaging studies, the initial uptake into tumor was weaker than in other thoracic and abdominal organs, but [18F]PTP-Ganetespib was retained relatively longer in the tumor than other organs. The uptake of [18F]PTP-Ganetespib in tumors was not sufficient for further development as a tumor-specific PET imaging agent by itself, but this preliminary PET imaging study of [18F]PTP-Ganetespib can be basis for developing new PET imaging agents based on HSP90 inhibitor, ganetespib.

Characterization and preliminary imaging evaluation of a clinical prototype stationary intraoral tomosynthesis system.

Technological advancements in dental radiography have improved oral care on many fronts, yet diagnostic efficacy for some of the most common oral conditions, such as caries, dental cracks and fractures, and periodontal disease, remains relatively low. Driven by the clinical need for a better diagnostic yield for these and other dental conditions, we initiated the development of a stationary intraoral tomosynthesis (s-IOT) imaging system using carbon nanotube (CNT) x-ray source array technology. Here, we report the system characterization and preliminary imaging evaluation of a clinical prototype s-IOT system approved for human use. The clinical prototype s-IOT system is comprised of a multibeam CNT x-ray source array, high voltage generator, control electronics, collimator cone, and dynamic digital intraoral detector. During a tomosynthesis scan, each x-ray source is operated sequentially at fixed, nominal tube current of 7mA and user-specified pulse width. Images are acquired by a digital intraoral detector and the reconstruction algorithm generates slice information in real time for operator review. In this study, the s-IOT system was characterized for tube output, dosimetry, and spatial resolution. Manufacturer specifications were validated, such as tube current, kVp, and pulse width. Tube current was measured with an oscilloscope on the analog output of the anode power supply. Pulse width, kVp, and peak skin dose were measured with a dosimeter with ion chamber and high voltage accessory. In-plane spatial resolution was evaluated via measurement of MTF and imaging of a line pair phantom. Spatial resolution in the depth direction was evaluated via artifact spread measurement. The size of the collimated radiation field was evaluated for compliance with FDA regulations. A dental phantom and human specimens of varying pathologies were imaged on a clinical 2D intraoral imaging system as well as s-IOT for comparison and to explore potential clinical applications. The measured tube current, kVp, and pulse width values were within 3% of the set values. A cumulative peak skin dose of 1.12mGy was measured for one complete tomosynthesis scan using a 50-ms pulse per projection view. Projection images and reconstruction slices revealed MTF values ranging from 8.1 to 9.3 cycles/mm. Line pair imaging verified this result. The radiation field was found to meet the FDA requirements for intraoral imaging devices. Tomosynthesis reconstruction slice images of the dental phantom and human specimens provided depth resolution, allowing visibility of anatomical features that cannot be seen in the 2D intraoral images. The clinical prototype s-IOT device was evaluated and found to meetall manufacturer specifications. Though the system capability is higher, initial investigations are targeting a low-dose range comparable to a single 2D radiograph. Preliminary studies indicated that s-IOT provides increased image quality and feature conspicuity at a dose comparable to a single 2D intraoral radiograph.

Management of a stable atlas fracture in a patient with comorbid schizophrenia and alcohol use disorder

To our knowledge, there are no existing case reports documenting how to treat a fracture of the high cervical spine in a nonadherent patient. In this case report, we present an adult male with longstanding diagnoses of schizophrenia and alcohol use disorder who originally presented with neck pain after a fall due to alcohol intoxication. He had already been placed in a cervical neck brace (C-collar) at presentation. Preliminary imaging revealed a fracture of the left lateral mass of C1 extending into the left transverse process of the odontoid, without significant widening of the joint, no involvement of the dens, and no vascular compromise. The C-collar remained in place and the patient was transferred to the intensive care unit (ICU) for monitoring of his fracture and alcohol withdrawal. The patient was admitted to the psychiatric unit nine days later through an involuntary hold to ensure proper initial care for the atlas fracture and address his primary psychotic disorder. The patient was ultimately lost to follow up. Because of the sensitive nature of the fracture, and the nonadherence of the patient due to his comorbid schizophrenia and alcohol use, orthopedic surgeons instituted a unique care plan to best suit this individual patient’s needs. In the management of stable high cervical fractures in patients with questionable adherence, conservative measures are more safe, plausible, and effective than surgical intervention.

Asymptomatic Transaminitis: A Case of Hepatic Sarcoidosis

Background: Sarcoidosis is a chronic inflammatory multisystem disease characterized by the presence of non-caseating granulomas. Pulmonary involvement is most common, however hepatic manifestations occur in up to 70% of cases.1 We present a patient with asymptomatic transaminitis who was found to have isolated hepatic sarcoidosis, a rare diagnosis. Case: A 47 year old female with a PMH of cholecystitis status post cholecystectomy, iron deficiency anemia and history of migraines presented for evaluation of abnormal liver enzymes. Labs were notable for AST 50-70s, ALT 60-80s, and ALP 122. She reported intermittent fevers, once a week, ranging from 99 - 101F, but denied chills or night sweats. Abdominal ultrasound and CT scan revealed peripancreatic and porta hepatis lymphadenopathy. PET scan showed increased uptake in corresponding regions. Inflammatory markers were elevated (CRP 21 and ESR 112). Hematologic work-up was unremarkable for malignancy or lymphoma. She underwent extensive serologic evaluation, which was unremarkable for autoimmune or infectious etiologies. Left lobe liver biopsy was performed after which patient started oral prednisone therapy. Biopsy results showed multiple non-caseating granulomas in portal and lobular distribution with mixed portal and periportal inflammation, as well as bile duct injury and lesions without evidence of fibrosis, steatosis, copper deposition, or stainable microorganisms. On follow-up, there was no significant improvement in transaminitis. ACE level elevated to 73. Steroids were discontinued and she is now being managed conservatively for hepatic sarcoidosis with close follow-up and discussion of long-term immunosuppressive therapy. Discussion: The etiology of sarcoidosis is still not well understood and presentations with only hepatic involvement are uncommon. This case demonstrates that isolated hepatic sarcoidosis, while a rare diagnosis, should be considered in asymptomatic patients with abnormalities in liver function tests whose preliminary laboratory and imaging work-up has been unrevealing. Serum ACE levels along with liver biopsy for histopathology provides a diagnostic clue. Management options include close medical observation, prednisone and/or ursodeoxycholic acid, as well as initiation of immunosuppressive agents.

An Atypical Case of Dysphagia: Left Atrial Enlargement

Background: Dysphagia in the elderly is often due to oropharyngeal or esophageal causes. Dysphagia due to cardiac etiology is an uncommon diagnosis.1 We present a case of dysphagia as a result of extrinsic esophageal compression secondary to left atrial enlargement. Case: A 93 year old male with a PMH of atrial fibrillation on Rivaroxaban and a remote history of throat cancer status post radiation twenty years prior presented with hypoxia and hypotension after an aspiration event. Medical history also included HFpEF (EF 55%), valvular heart disease (Aortic Stenosis and Mitral Regurgitation) and coronary artery disease status post coronary artery bypass grafting (CABG) in 1998. Initial Chest X-Ray showed multifocal airspace disease in right upper and bilateral lower lobes as well as cardiomegaly (Figure 1). He was initially admitted to the ICU for aspiration pneumonia and septic shock requiring pressor support, then transferred to the medical floors after stabilization. Modified Barium Swallow study showed no evidence of laryngeal penetration or aspiration, yet patient continued to have episodes of post-prandial emesis during hospitalization. Endoscopy revealed incidental Schatzki ring at the gastroesophageal junction but was otherwise normal. Full Barium Swallow study revealed marked esophageal dysmotility with evidence of extrinsic compression on the distal portion of esophagus, resulting in delayed emptying of the proximal esophagus. CT Chest revealed compression of the esophagus secondary to left atrial enlargement (Figure 2). Cardiology evaluated patient and transthoracic echocardiogram confirmed left atrial dilatation and elevated filling pressures. Patient noted to have some symptomatic improvement with gentle diuresis and options for PEG tube were discussed, though not pursued as this was not in line with patient's goals of care.1777_A Figure 1. Initial CXR showing cardiomegaly and multifocal airspace disease1777_B Figure 2. CT Chest revealing atrial compression of esophagusDiscussion: Initial evaluation and management of dysphagia in the elderly begins with a comprehensive history and physical exam. This case demonstrates that when preliminary laboratory and imaging workup is unrevealing, re-assessing the anatomic location of swallowing dysfunction can help to provide a diagnostic clue. While cardiovascular dysphagia is uncommon, it should be on the differential in patients with risk factors for left atrial enlargement.

Synthesis and biodistribution of novel dansyl derivative 11C-DSB

A novel 11C-labeled dansyl 1, 2-diphenylethene derivative for positron emission tomography (PET) imaging of β-amyloid (Aβ) plaques and apoptosis in the brain of Alzheimer’s disease (AD) was designed and synthesized. The 11C-labeled tracer, (E)-5-(dimethylamino)-N-(4-(4-11C-methoxystyryl)phenyl)-naphthalene-1-sulfonamide (11C-DSB), was synthesized. The decay-corrected radiochemistry yield was 20 ± 5% (n = 5) from 11C–CO2 within 20 min and the specific activity of 1.6 GBq/µmol. Moreover, in vivo biodistribution and preliminary PET imaging of normal mice were performed to show that 11C-DSB had moderate brain penetration and washout. But11C-DSB has high log P value, showing that its structure needs to be further improved to increase its water solubility. The results provide the basis for further research on PET and fluorescence dual-modality imaging of AD models.

Anatomical Structure Segmentation in Ultrasound Volumes Using Cross Frame Belief Propagating Iterative Random Walks.

Ultrasound (US) is widely used as a low-cost alternative to computed tomography or magnetic resonance and primarily for preliminary imaging. Since speckle intensity in US images is inherently stochastic, readers are often challenged in their ability to identify the pathological regions in a volume of a large number of images. This paper introduces a generalized approach for volumetric segmentation of structures in US images and volumes. We employ an iterative random walks (IRW) solver, a random forest learning model, and a gradient vector flow (GVF) based interframe belief propagation technique for achieving cross-frame volumetric segmentation. At the start, a weak estimate of the tissue structure is obtained using estimates of parameters of a statistical mechanics model of US tissue interaction. Ensemble learning of these parameters further using a random forest is used to initialize the segmentation pipeline. IRW is used for correcting the contour in various steps of the algorithm. Subsequently, a GVF-based interframe belief propagation is applied to adjacent frames based on the initialization of contour using information in the current frame to segment the complete volume by frame-wise processing. We have experimentally evaluated our approach using two different datasets. Intravascular ultrasound (IVUS) segmentation was evaluated using 10pullbacks acquired at 20MHz and thyroid US segmentation is evaluated on 16 volumes acquired at [Formula: see text]MHz. Our approach obtains a Jaccard score of [Formula: see text] for IVUS segmentation and [Formula: see text] for thyroid segmentation while processing each frame in [Formula: see text] for the IVUS and in [Formula: see text] for thyroid segmentation without the need of any computing accelerators such as GPUs.

Tetrahydro[5]helicene-based fluorescent probe for rapid and sensitive detection of bisulfite in living cells

A new fluorescent probe tetrahydro[5]helicene-malononitrile derivative was designed and synthesized for selective detection of bisulfite. This fluorescent probe exhibites high response speed and selectivity toward HSO3− in PBS solution over other coexisting species accompanied by a distinct fluorescence color change from yellow to blue, which can be visually identified. The probe shows excellent sensitivity to HSO3− and the detection limit is as low as 0.27 μM. Once reacted with HSO3−, the signal-to-background ratio of fluorescence intensity can reach a 45-folds enhancement and the quantum yield dramatically increases from 1.9% to 52.3%. The response mechanism proved to be a nucleophilic addition reaction of probe with HSO3−, which was confirmed by 1H NMR, Mass titration and theory calculation. Additionally, the preliminary cell imaging experiments demonstrated that the probe could be used for intracellular bisulfite detection.

Preclinical study of an 18F-labeled glutamine derivative for cancer imaging

IntroductionThe emerging evidence that demonstrated the extra-demand of glutamine for cancer surviving strongly called for the development of PET tracer for imaging glutamine uptake in cancer. In this work, [18F]Gln-BF3 as a natural glutamine derivative was synthesized to explore its potential application of imaging glutamine uptake for cancer diagnosis. Methods[18F]Gln-BF3 was prepared by deprotection of purified precursor trityl-Gln-BF3 (amide bond protected with triphenylmethyl group) using TFA and radiolabeled using 18F–19F isotope exchange protocol. PET imaging and biodistribution studies were conducted in Balb/c mice bearing 4T1 xenograft. ResultsGln-BF3 was identified with HRMS ([M-H]− = 169.0765). [18F]Gln-BF3 was radiolabeled in high radiochemical yield (RCY > 25%) and characterized with Radio-HPLC-MS. Preliminary PET imaging showed the radioactivity was fast cleared from muscle tissue and excreted mainly via the renal pathway. PET study demonstrated that uptake of [18F]Gln-BF3 in 4T1 xenografts was significant. The biodistribution results of [18F]Gln-BF3 in mice bearing 4T1 xenograft indicate a tumor-to-muscle ratio of 2.58 ± 0.64 (n = 4) and a 6.29 ± 0.42%ID/g (n = 4) uptake in tumor at 45 min post injection. Conclusion[18F]Gln-BF3 was radiolabeled in a “kit-like” manner and showed notable and tumor-selective uptake in tumor-bearing animal models, suggesting that this new strategy of radiolabeling amino acid provided a promising solution for the future development of glutamine-derived PET tracers.

Multichannel simultaneous dual-band fully polarimetric airborne synthetic aperture radar: system features and experimental results

This paper presents a frequency modulated continuous wave (FMCW) technology-based airborne synthetic aperture radar (SAR) system. This radar system operates on an eight-channel simultaneous dual band (X- and L-bands) in fully polarimetric mode. Compared with the traditional multiband airborne SAR, this radar system features a small size and low power consumption based on the FMCW technology. The antenna subsystem can be easily mounted behind the cargo door of a small aircraft platform without any modifications to the aircraft structure. A Cessna 208 is employed to mount this radar system in a left side looking installation. A single pass flight test is carried out in China, and preliminary imaging results are acquired and classified. The merged X–L band image provides the highest classification accuracy compared with the single X- and L-bands and optical images. The experimental results indicate that the proposed FMCW SAR is a powerful tool for terrain classification, especially for rural-urban region classification.

Jugular bulb and skull base pathologies: proposal for a novel classification system for jugular bulb positions and microsurgical implications.

OBJECTIVE There is no definitive or consensus classification system for the jugular bulb position that can be uniformly communicated between a radiologist, neurootologist, and neurosurgeon. A high-riding jugular bulb (HRJB) has been variably defined as a jugular bulb that rises to or above the level of the basal turn of the cochlea, within 2 mm of the internal auditory canal (IAC), or to the level of the superior tympanic annulus. Overall, there is a seeming lack of consensus, especially when MRI and/or CT are used for jugular bulb evaluation without a dedicated imaging study of the venous anatomy such as digital subtraction angiography or CT or MR venography. METHODS A PubMed analysis of "jugular bulb" comprised of 1264 relevant articles were selected and analyzed specifically for an HRJB. A novel classification system based on preliminary skull base imaging using CT is proposed by the authors for conveying the anatomical location of the jugular bulb. This new classification includes the following types: type 1, no bulb; type 2, below the inferior margin of the posterior semicircular canal (SCC), subclassified as type 2a (without dehiscence into the middle ear) or type 2b (with dehiscence into the middle ear); type 3, between the inferior margin of the posterior SCC and the inferior margin of the IAC, subclassified as type 3a (without dehiscence into the middle ear) and type 3b (with dehiscence into the middle ear); type 4, above the inferior margin of the IAC, subclassified as type 4a (without dehiscence into the IAC) and type 4b (with dehiscence into the IAC); and type 5, combination of dehiscences. Appropriate CT and MR images of the skull base were selected to validate the criteria and further demonstrated using 3D reconstruction of DICOM files. The microsurgical significance of the proposed classification is evaluated with reference to specific skull base/posterior fossa pathologies. RESULTS The authors validated the role of a novel classification of jugular bulb location that can help effective communication between providers treating skull base lesions. Effective utilization of the above grading system can help plan surgical procedures and anticipate complications. CONCLUSIONS The authors have proposed a novel anatomical/radiological classification system for jugular bulb location with respect to surgical implications. This classification can help surgeons in complication avoidance and management when addressing HRJBs.

Simulation Analysis and Performance Testing Investigation of Capacitive Micromachined Ultrasonic Transducer

In various applications of ultrasonic waves, the ultrasonic transducer is the key device of ultrasonic testing and ultrasonic imaging. Compared with the traditional piezoelectric transducer, the capacitive micromachined ultrasonic transducer (CMUT) has many striking advantages, such as low impedance, high bandwidth, easy integration and low cost, and it is expected to become a next generation of mainstream products. In this paper, a CMUT structure for underwater-imaging applications is designed, and the finite element model is established by using COMSOL software, then the modal analysis, harmonic response analysis, electromechanical coupling analysis and transient analysis are carried out. As a consequence, the key parameters of CMUT are obtained, namely resonance frequency, voltage collapse and electromechanical coupling coefficient. For the processed CMUT line array consisting of 16 elements, a test system is built and the emission performance, receiving performance, directivity, bandwidth and preliminary imaging of the designed transducer are tested and analyzed. The results show that the designed CMUT array can meet the requirements of underwater-imaging applications.