Impact of various iodine concentrations of iohexol and iodixanol contrast media on image reconstruction techniques in a vascular-specific contrast media phantom: quantitative and qualitative image quality assessment.

PURPOSE: The aim of our study is to investigate the impact of iodine quantification on image reconstruction when employing a vascular-specific contrast media phantom with varying iodine concentrations. MATERIALS AND METHODS: A 30-cm phantom simulating arterial and venous blood vessel diameters was manufactured. Small (9 mm) and medium (12 mm) cylinders contained iodine concentrations from 10 to 100% while large (21 mm) cylinders were in quartiles from 25 to 100% diluted in blood equivalent medium. Each phantom was filled with either iohexol 350 mgI/mL (Group A) or iodixanol 320 mgI/mL (Group B) and then scanned separately. For each group, tube potential (80-140 kVp) and current (50-400 mAs) were changed and all image series were reconstructed with filtered back projection (FBP), hybrid-based iterative reconstruction (HBIR) and model-based iterative reconstruction (MBIR). Mean opacification was measured in all groups. All data were compared employing an independent t test and Pearson's correlation. Visual grading characteristic (VGC) and Cohens' kappa analyses were performed. RESULTS: At 80 kVp, mean opacification using HBIR was significantly higher in Group B (2165 ± 1108 HU) than in Group A (2040 ± 1036 HU) (p < 0.009). At 140 kVp, MBIR and HBIR were greater in Group A (1704 ± 1033 HU and 1685 ± 1023 HU) versus Group B (1567 ± 1036 HU and 1567 ± 1034 HU) (p < 0.022). CNR using FBP, HBIR and MBIR was higher in Group B (46 ± 42 HU, 70 ± 163 HU and 83 ± 74 HU, respectively) than in Group A (43 ± 39 HU, 174 ± 130 HU and 80 ± 65 HU, respectively) (p < 0.0001-0.035). Qualitative image analysis demonstrated no difference in Cohen's kappa analysis. VGC was higher in Group A at all image reconstruction groups. CONCLUSION: Iohexol outperforms iodixanol in observer performance when assessing image reconstruction techniques and iodine concentrations in a vascular-specific contrast media phantom.

Membrane protein structure determination by SAD, SIR, or SIRAS phasing in serial femtosecond crystallography using an iododetergent.

The 3D structure determination of biological macromolecules by X-ray crystallography suffers from a phase problem: to perform Fourier transformation to calculate real space density maps, both intensities and phases of structure factors are necessary; however, measured diffraction patterns give only intensities. Although serial femtosecond crystallography (SFX) using X-ray free electron lasers (XFELs) has been steadily developed since 2009, experimental phasing still remains challenging. Here, using 7.0-keV (1.771 Å) X-ray pulses from the SPring-8 Angstrom Compact Free Electron Laser (SACLA), iodine single-wavelength anomalous diffraction (SAD), single isomorphous replacement (SIR), and single isomorphous replacement with anomalous scattering (SIRAS) phasing were performed in an SFX regime for a model membrane protein bacteriorhodopsin (bR). The crystals grown in bicelles were derivatized with an iodine-labeled detergent heavy-atom additive 13a (HAD13a), which contains the magic triangle, I3C head group with three iodine atoms. The alkyl tail was essential for binding of the detergent to the surface of bR. Strong anomalous and isomorphous difference signals from HAD13a enabled successful phasing using reflections up to 2.1-Å resolution from only 3,000 and 4,000 indexed images from native and derivative crystals, respectively. When more images were merged, structure solution was possible with data truncated at 3.3-Å resolution, which is the lowest resolution among the reported cases of SFX phasing. Moreover, preliminary SFX experiment showed that HAD13a successfully derivatized the G protein-coupled A2a adenosine receptor crystallized in lipidic cubic phases. These results pave the way for de novo structure determination of membrane proteins, which often diffract poorly, even with the brightest XFEL beams.

Extracellular Vesicles Isolated from the Leaf Apoplast Carry Stress-Response Proteins.

Exosomes are extracellular vesicles (EVs) that play a central role in intercellular signaling in mammals by transporting proteins and small RNAs. Plants are also known to produce EVs, particularly in response to pathogen infection. The contents of plant EVs have not been analyzed, however, and their function is unknown. Here, we describe a method for purifying EVs from the apoplastic fluids of Arabidopsis (Arabidopsis thaliana) leaves. Proteomic analyses of these EVs revealed that they are highly enriched in proteins involved in biotic and abiotic stress responses. Consistent with this finding, EV secretion was enhanced in plants infected with Pseudomonas syringae and in response to treatment with salicylic acid. These findings suggest that EVs may represent an important component of plant immune responses.

The Influence of Contrast Agent's Osmolarity on Iodine Delivery Protocol in Coronary Computed Tomography Angiography: Comparison Between Iso-Osmolar Iodixanol-320 and Low-Osmolar Iomeprol-370.

OBJECTIVES: This study aims to assess whether iodine-contained contrast agents with different osmolarity affect iodine delivery protocol during coronary computed tomography angiography (CCTA). METHODS: Patients who underwent CCTA were randomized to receive contrast media either iodixanol-320 (iso-osmolar group) or iopromide-370 (low-osmolar group). Contrast protocols were recorded. Tube voltage of 100 kV was chosen for patients with body mass index of less than or equal to 25 (n = 224) and tube voltage of 120 kV for patients with body mass index of greater than 25 (n = 165). Both groups applied automatic current modulation technique. Mean contrast enhancement of the ascending aorta, left main coronary artery, and descending aorta was calculated. Simulated contrast flow rate and iodine delivery rate (IDR) to reach a mean contrast enhancement level of 350 HU were calculated. RESULTS: A total of the 389 patients were enrolled in the study. To achieve the same contrast enhancement of 350 HU, iso-osmolar group required higher simulated contrast flow rate (3.90 vs 3.62 mL/s, P = 0.017) but lower simulated IDR (1.34 vs 1.25 g/s, P = 0.024) compared with low-osmolar group. CONCLUSIONS: To maintain a similar level of contrast enhancement during CCTA, iodixanol-320 needs larger contrast flow rate with lower IDR compared with low-osmolar iopromide-370.

Application of BOLD MRI and DTI for the evaluation of renal effect related to viscosity of iodinated contrast agent in a rat model.

PURPOSE: To evaluate the effects of viscosity of contrast agent (CA) on intrarenal oxygenation and diffusion as measured by blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) in a rat model. MATERIALS AND METHODS: Radiocontrast iodixanol formulated in three viscosities were designated 270, 320, and 350 (mg iodine/mL). Sixty-three male Wistar rats were divided into four groups. Saline and iodixanol (4 g iodine/kg) were administered. MR images were acquired on a 3.0T scanner at baseline and at 1 hour, 24 hours, 48 hours, and 72 hours postinjection of solutions. BOLD-MRI was performed with a multiple gradient-recalled-echo sequence. The changes in R2*, apparent diffusion coefficient (ADC), fractional anisotropy (FA), histology, and hypoxia-inducible factor-1α (HIF-1α) immunoexpression were evaluated. The R2*, ADC, and FA values were normalized to baseline to calculate ΔR2*, ΔADC, and ΔFA. RESULTS: Compared with baseline levels, distinct elevation of ΔR2* (P < 0.05) and obvious decrease in ΔADC (P < 0.01) and ΔFA (P < 0.05) were observed in all the anatomical compartments at 1 hour after administration of CA. The absolute values in ΔR2*, ΔADC, and ΔFA increased with increases in CA viscosity, and differed significantly between the CA groups in renal cortex (CO), outer stripe of outer medulla (OSOM), and inner stripe of outer medulla (ISOM) (all P < 0.05). A significant positive correlation was observed between ΔR2* and HIF-1α expression (P < 0.001, r = 0.75). Significant negative correlations were observed between ΔADC, ΔFA, and pathologies in CO, OSOM, ISOM (all P < 0.001, r = -0.68-0.87; all P < 0.001, r = -0.60-0.66). CONCLUSION: The effect of CA viscosity on intrarenal oxygenation and diffusion was viscosity-dependent, and was identified using BOLD-MRI and DTI. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1320-1331.

Acute kidney damage induced by low- and iso-osmolar contrast media in rats: Comparison study with physiologic MRI and histologic-gene examination.

PURPOSE: To investigate the physiopathological effects of low- and iso-osmolar contrast media (CM) on renal function with physiologic MRI and histologic-gene examination. MATERIALS AND METHODS: Forty-eight rats underwent time-course DWI and DCE-MRI at 3.0 Tesla (T) before and 5-15 min after exposure of CM or saline (Iop.370: 370 mgI/mL iopromide; Iod.320: 320 mgI/mL iodixanol; Iod.270: 270 mgI/mL iodixanol; 4 gI/kg body weight). Intrarenal viscosity was reflected by apparent diffusion coefficient (ADC). Renal physiologies were evaluated by DCE-derived glomerular filtration rate (GFR), renal blood flow (RBF), and renal blood volume (RBV). Potential acute kidney injury (AKI) was determined by histology and the expression of kidney injury molecule 1 (Kim-1). RESULTS: Iop.370 mainly increased ADC in inner-medulla (△ADCIM : 12.3 ± 11.1%; P < 0.001). Iod.320 and Iod.270 mainly decreased ADC in outer-medulla (△ADCIM ; Iod.320: 16.8 ± 7.5%; Iod.270: 18.1 ± 9.5%; P < 0.001) and inner-medulla (△ADCIM ; Iod.320: 28.4 ± 9.3%; Iod.270: 30.3 ± 6.3%; P < 0.001). GFR, RBF and RBV were significantly decreased by Iod.320 (△GFR: 45.5 ± 24.1%; △RBF: 44.6 ± 19.0%; △RBV: 35.2 ± 10.1%; P < 0.001) and Iod.270 (33.2 ± 19.0%; 38.1 ± 15.6%; 30.1 ± 10.1%; P < 0.001), while rarely changed by Iop.370 and saline. Formation of vacuoles and increase in Kim-1 expression was prominently detected in group of Iod.320, while rarely in Iod.270 and Iop.370. CONCLUSION: Iso-osmolar iodixanol, given at high-dose, produced prominent AKI in nonhydrated rats. This renal dysfunction could be assessed noninvasively by physiologic MRI. LEVEL OF EVIDENCE: 1 J. Magn. Reson. Imaging 2017;45:291-302.

Size Determination of a Liposomal Drug by Small-Angle X-ray Scattering Using Continuous Contrast Variation.

The continuously growing complexity of nanodrugs urges for complementary characterization techniques which can elude the current limitations. In this paper, the applicability of continuous contrast variation in small-angle X-ray scattering (SAXS) for the accurate size determination of a complex nanocarrier is demonstrated on the example of PEGylated liposomal doxorubicin (Caelyx). The mean size and average electron density of Caelyx was determined by SAXS using a gradient of aqueous iodixanol (Optiprep), an iso-osmolar suspending medium. The study is focused on the isoscattering point position and the analysis of the Guinier region of the scattering curves recorded at different solvent densities. An average diameter of (69 ± 5) nm and electron density of (346.2 ± 1.2) nm(-3) were determined for the liposomal formulation of doxorubicin. The response of the liposomal nanocarrier to increasing solvent osmolality and the structure of the liposome-encapsulated doxorubicin after the osmotic shrinkage of the liposome are evaluated with sucrose contrast variation in SAXS and wide-angle X-ray scattering (WAXS). In the case of using sucrose as contrast agent, a clear osmolality threshold at 670 mOsm kg(-1) was observed, above which the liposomal drug carriers start to shrink, though preserving the intraliposomal doxorubicin structure. The average size obtained by this technique is smaller than the value measured by dynamic light scattering (DLS), though this difference is expected due to the hydrodynamic size of the PEG moieties attached to the liposomal surface, which are not probed with solvent contrast variation in SAXS. The advantages and drawbacks of the proposed technique are discussed in comparison to DLS, the most frequently used sizing method in nanomedicine.

Synthesis and characterization of image-able polyvinyl alcohol microspheres for image-guided chemoembolization.

Therapeutic embolization of blood vessels is a minimally invasive, catheter-based procedure performed with solid or liquid emboli to treat bleeding, vascular malformations, and vascular tumors. Hepatocellular carcinoma (HCC) affects about half a million people per year. When unresectable, HCC is treated with embolization and local drug therapy by transarterial chemoembolization (TACE). For TACE, drug eluting beads (DC Bead(®)) may be used to occlude or reduce arterial blood supply and deliver chemotherapeutics locally to the tumor. Although this treatment has been shown to be safe and to improve patient survival, the procedure lacks imaging feedback regarding the location of embolic agent and drug coverage. To address this shortcoming, herein we report the synthesis and characterization of image-able drug eluting beads (iBeads) from the commercial DC Bead(®) product. Two different radiopaque beads were synthesized. In one approach, embolic beads were conjugated with 2,3,5-triiodobenzyl alcohol in the presence of 1,1'-carbonyldiimidazol to give iBead I. iBead II was synthesized with a similar approach but instead using a trimethylenediamine spacer and 2,3,5-triiodobenzoic acid. Doxorubicin was loaded into the iBeads II using a previously reported method. Size and shape of iBeads were evaluated using an upright microscope and their conspicuity assessed using a clinical CT and micro-CT. Bland and Dox-loaded iBeads II visualized with both clinical CT and microCT. Under microCT, individual bland and Dox loaded beads had a mean attenuation of 7904 ± 804 and 11,873.96 ± 706.12 HU, respectively. These iBeads have the potential to enhance image-guided TACE procedures by providing localization of embolic-particle and drug.

[Applied research of CT angiography of lower extremities by using 100 kVp and iodixanol(270 mg I/ml) combined with iDose(4) iterative reconstruction technique].

OBJECTIVE: To evaluate the feasibility of CT angiography of lower extremities by using 100 kVp as tube voltage and Iodixanol(270 mg I/ml) as contrast medium combined with iDose(4) iterative reconstruction technique. METHODS: A total of 52 continuous patients with clinically suspected lesions of lower extremity arteries underwent CT angiography of lower extremities, divided into 2 groups, and different scan protocols were adopted. "double low" group included 26 patients using 100 kVp, Iodixanol (270 mg I/ml) and iDose(4) -4 iterative reconstruction algorithm; routine group included 26 patients using 120 kVp, Iopromide(370 mg I/ml) and filtered back projection reconstruction algorithm. The total amount of contrast medium in both groups was 95 ml. Artery CT value and background noise at the level of L4 vertebral, hip, knee and ankle were measured, signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated, and the quality of images was evaluated subjectively. Scan length (L), volume CT dose index (CTDI(VOL)) and dose length product(DLP) were recorded, and the effective dose (ED) was calculated. The measurement results and subjective evaluation were analyzed statistically. CTA results were analyzed with the digital subtraction angiography (DSA) as the "gold standard". RESULTS: (1) No significant difference was existed in gender, age, height, weight and body mass index (BMI) of these two groups (P > 0.05). (2) No significant difference was existed in artery CT value, SNR and CNR at the level of L4 vertebral, hip, knee and ankle of the two groups (P > 0.05). Compared with routine group, background noise of "double low" group at the level of hip and knee increased by 16.6% and 13.8%, respectively (P < 0.05). (3) The image quality of the two groups met the requirement of diagnosis, no significant statistical difference was existed in subjective evaluation (P > 0.05). (4) The CTDI(VOL), DLP, ED of "double low" group were lower than that of routine group, with significant statistical difference (P < 0.05). The total amount of iodine in "double group" was lower than that of routine group (25.6 g vs 35.2 g). (5) A total of 7 cases from "double low" group underwent DSA examination, and 18 pathological changes (stenosis and occlusion) were found totally, in which 16 matched CTA; 6 cases from routine group underwent DSA examination, and 15 pathological changes (stenosis and occlusion) were found totally, in which 13 matched. CTA. No significant statistical difference was existed between the two groups in diagnostic efficacy (P = 0.626). CONCLUSIONS: Using 100 kVp and Iodixanol (270 mg I/ml) combined with iDose(4) -4 iterative reconstruction technique for CT angiography of lower extremities, the image quality could meet the requirement for clinical diagnosis, the radiation dose and the volume of contrast medium could be lowered.

A Streamlined and Standardized Procedure for Generating High-Titer, High-Quality Adeno-Associated Virus Vectors Utilizing a Cell Factory Platform.

Preclinical gene therapy research, particularly in rodent and large animal models, necessitates the production of AAV vectors with high yield and purity. Traditional approaches in research laboratories often involve extensive use of cell culture dishes to cultivate HEK293T cells, a process that can be both laborious and problematic. Here, a unique in-house method is presented, which simplifies this process with a specific cell factory (or cell stacks, CF10) platform. An integration of polyethylene glycol/aqueous two-phase partitioning with iodixanol gradient ultracentrifugation improves both the yield and purity of the generated AAV vectors. The purity of the AAV vectors is verified through SDS-PAGE and silver staining, while the ratio of full to empty particles is determined using transmission electron microscopy (TEM). This approach offers an efficient cell factory platform for the production of AAV vectors at high yields, coupled with an improved purification method to meet the quality demands for in vivo studies.

Effect of iodixanol and propylene glycol as clearing agents in extensor digitorum longus and soleus muscles: mechanical and morphological characterization using the optical coherence tomography technique.

Soft tissue engineering and regenerative medicine aim to address the intricate relationship between tissue architecture and biomechanical performance. The traditional technique used to analyze muscular architectures is histology. However, optical coherence tomography is a novel non-destructive, non-invasive imaging tool that provides real-time, high-resolution visualization of tissue microstructure, making it applicable to soft tissues. High-quality images, minimized light scattering, and different clearing agents, such as propylene glycol and iodixanol, have been employed. A stress-relaxation test was performed to characterize the effects of clearing agents on rat extensor digitorum longus and soleus muscles. Additionally, muscle fiber structure images obtained using optical correlation tomography were compared with histological images to corroborate the high precision of the optical method. The results showed that iodixanol is a promising clearing agent for characterizing muscles as it provides good quality images and a satisfactory reversibility process with no permanent damage to the extracellular matrix or muscle fiber structure of the tissue.

Separation of the principal HDL subclasses by iodixanol ultracentrifugation.

HDL subclasses detection, in cardiovascular risk, has been limited due to the time-consuming nature of current techniques. We have developed a time-saving and reliable separation of the principal HDL subclasses employing iodixanol density gradient ultracentrifugation (IxDGUC) combined with digital photography. HDL subclasses were separated in 2.5 h from prestained plasma on a three-step iodixanol gradient. HDL subclass profiles were generated by digital photography and gel scan software. Plasma samples (n = 46) were used to optimize the gradient for the resolution of HDL heterogeneity and to compare profiles generated by IxDGUC with gradient gel electrophoresis (GGE); further characterization from participants (n = 548) with a range of lipid profiles was also performed. HDL subclass profiles generated by IxDGUC were comparable to those separated by GGE as indicated by a significant association between areas under the curve for both HDL2 and HDL3 (HDL2, r = 0.896, P < 0.01; HDL3, r = 0.894, P < 0.01). The method was highly reproducible, with intra- and interassay coefficient of variation percentage < 5 for percentage area under the curve HDL2 and HDL3, and < 1% for peak Rf and peak density. The method provides time-saving and cost-effective detection and preparation of the principal HDL subclasses.

Purification of white spot syndrome virus by iodixanol density gradient centrifugation.

Up to now, only a few brief procedures for purifying white spot syndrome virus (WSSV) have been described. They were mainly based on sucrose, NaBr and CsCl density gradient centrifugation. This work describes for the first time the purification of WSSV through iodixanol density gradients, using virus isolated from infected tissues and haemolymph of Penaeus vannamei (Boone). The purification from tissues included a concentration step by centrifugation (2.5 h at 60,000 g) onto a 50% iodixanol cushion and a purification step by centrifugation (3 h at 80,000 g) through a discontinuous iodixanol gradient (phosphate-buffered saline, 5%, 10%, 15% and 20%). The purification from infected haemolymph enclosed a dialysis step with a membrane of 1,000 kDa (18 h) and a purification step through the earlier iodixanol gradient. The gradients were collected in fractions and analysed. The number of particles, infectivity titre (in vivo), total protein and viral protein content were evaluated. The purification from infected tissues gave WSSV suspensions with a very high infectivity and an acceptable purity, while virus purified from haemolymph had a high infectivity and a very high purity. Additionally, it was observed that WSSV has an unusually low buoyant density and that it is very sensitive to high external pressures.

Intrarenal oxygenation by blood oxygenation level-dependent MRI in contrast nephropathy model: effect of the viscosity and dose.

PURPOSE: To compare the effects of osmolality versus viscosity of radio-contrast media on intra-renal oxygenation as determined by blood oxygenation level-dependent (BOLD) MRI in a model of contrast induced nephropathy (CIN). MATERIALS AND METHODS: Twenty-four Sprague-Dawley rats were divided into five groups. Nitric oxide synthase inhibitor L-NAME (10 mg/kg), cyclooxygenase inhibitor indomethacin (10 mg/kg), or saline, and radio-contrast iodixanol (high viscosity, 784 or 1600 mg I/kg) or iothalamate (high osmolality, 1600 mg I/kg) were administered. BOLD MRI images were acquired on Siemens 3 Tesla (T) scanner using a multiple gradient recalled echo sequence at baseline, following L-NAME (or saline), indomethacin (or saline), and radio-contrast agents. R2* (=1/T2*) was used as the BOLD MRI parameter in renal medulla and cortex. Mixed-effects models with first order auto-regressive variance-covariance models were used to analyze the data. RESULTS: The magnitude of change in medullary R2* (MR2*) with same dose of iodine was larger with iodixanol compared with iothalalmate both in pretreated groups (303% versus 225.6%, < 0.01) and the control group (191.6% versus -1.8%, P < 0.01). The MR2* change in high dose iodixanol was approximately twice compared with the low dose (303% versus 133%, P < 0.01). CONCLUSION: The viscosity of radio-contrast seems to play a more significant role than osmolality in terms of renal oxygenation changes as evaluated by BOLD MRI. Additionally, iodixanol induced a dose-dependent increase in renal medullary hypoxia.

Varicocele retrograde embolization with boiling contrast medium and gelatin sponges in adolescent subjects: a clinically effective therapeutic alternative.

PURPOSE: Varicoceles occur in approximately 15% of adolescent male subjects and may impair future fertility. The present study describes a varicocele treatment technique involving percutaneous retrograde embolization with boiling hot contrast medium and gelatin sponge pledgets. MATERIALS AND METHODS: A retrospective review of medical records and imaging of all patients who underwent percutaneous retrograde varicocele embolization from 2005 to 2010 was performed. Pre- and postembolization symptoms, physical findings, and ultrasound findings were documented. Fifteen patients (16 embolizations) were identified, with an average age of 15.9 years (range, 12-18 y). Nine were referred because of persistent varicocele after surgical ligation. Three had grade 2 and nine had grade 3 varicoceles. Two had grade 1 varicoceles; one was painful and one was associated with poor semen quality. One varicocele was not clinically evident, but was associated with persistently decreased testicular size. Nine patients had pain or discomfort, and six had no discomfort. Clinical resolution was defined by a combination of symptom resolution and a lack of physical examination findings of varicocele or findings of treated varicocele. RESULTS: Fifteen of the 16 embolizations (94%) were technically successful. Clinical resolution was documented in 14 of 15 patients (95%); one patient experienced a recurrence at 30 months, which was successfully reembolized. One patient experienced temporary paresthesia of the left thigh. There were no major postprocedural complications. Mean follow-up duration was 11 months. CONCLUSIONS: Retrograde embolization of varicoceles in adolescent subjects with the use of boiling hot contrast medium and gelatin sponges is a promising technique that appears effective.

Experimental first-pass method for testing and comparing sorbent polymers used in the clearance of iodine contrast materials.

BACKGROUND: Sorbents have been shown to adsorb iodinated radiocontrast media. OBJECTIVE: In this study we describe a simple method to compare various sorbents in terms of capacity to adsorb radiocontrast media. METHODS: Iodixanol solution was injected into columns filled with three types of sorbent at filtration velocities of increasing magnitude. Two variables of interest - contrast removal rate and matched iodine retention (MIR) - were calculated to measure the adsorption efficiency and the mass of contrast iodine adsorbed versus sorbent used, respectively. RESULTS: The highest contrast removal and MIR for Porapak Q, CST 401 and Amberlite XAD4 were 41, 38 and 16% (p = 0.22 and 0.0005 for comparisons between Porapak Q-CST 401 and CST 401-Amberlite XAD4) and 0.060, 0.055 and 0.024, respectively (p = 0.18 and 0.0008). Extrapolation to a clinical scenario may suggest that removal of 8 ml iodixanol could be achieved by masses of sorbents of 43, 47 and 107 g, respectively. CONCLUSION: In this study we set a benchmark for comparing the radiocontrast-adsorbing efficiency of polymer sorbents during first-pass experiments, using a readily available methodology.

Development and application of a multimodal contrast agent for SPECT/CT hybrid imaging.

Hybrid or multimodality imaging is often applied in order to take advantage of the unique and complementary strengths of individual imaging modalities. This hybrid noninvasive imaging approach can provide critical information about anatomical structure in combination with physiological function or targeted molecular signals. While recent advances in software image fusion techniques and hybrid imaging systems have enabled efficient multimodal imaging, accessing the full potential of this technique requires development of a new toolbox of multimodal contrast agents that enhance the imaging process. Toward that goal, we report the development of a hybrid probe for both single photon emission computed tomography (SPECT) and X-ray computed tomography (CT) imaging that facilitates high-sensitivity SPECT and high spatial resolution CT imaging. In this work, we report the synthesis and evaluation of a novel intravascular, multimodal dendrimer-based contrast agent for use in preclinical SPECT/CT hybrid imaging systems. This multimodal agent offers a long intravascular residence time (t(1/2) = 43 min) and sufficient contrast-to-noise for effective serial intravascular and blood pool imaging with both SPECT and CT. The colocalization of the dendritic nuclear and X-ray contrasts offers the potential to facilitate image analysis and quantification by enabling correction for SPECT attenuation and partial volume errors at specified times with the higher resolution anatomic information provided by the circulating CT contrast. This may allow absolute quantification of intramyocardial blood volume and blood flow and may enable the ability to visualize active molecular targeting following clearance from the blood.

Derivatization of Protein Crystals with I3C using Random Microseed Matrix Screening.

Protein structure elucidation using X-ray crystallography requires both high quality diffracting crystals and computational solution of the diffraction phase problem. Novel structures that lack a suitable homology model are often derivatized with heavy atoms to provide experimental phase information. The presented protocol efficiently generates derivatized protein crystals by combining random microseeding matrix screening with derivatization with a heavy atom molecule I3C (5-amino-2,4,6-triiodoisophthalic acid). By incorporating I3C into the crystal lattice, the diffraction phase problem can be efficiently solved using single wavelength anomalous dispersion (SAD) phasing. The equilateral triangle arrangement of iodine atoms in I3C allows for rapid validation of a correct anomalous substructure. This protocol will be useful to structural biologists who solve macromolecular structures using crystallography-based techniques with interest in experimental phasing.