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Idiopathic pulmonary fibrosis is a progressive disease with unsatisfactory systemic treatments. Aerosol drug delivery to the lungs is expected to be an interesting route of administration. However, due to the alterations of lung compliance caused by fibrosis, local delivery remains challenging. This work aimed to develop a practical, relevant and ethically less restricted ex vivo respiratory model of fibrotic lung for regional aerosol deposition studies. This model is composed of an Ear-Nose-Throat replica connected to a sealed enclosure containing an ex vivo porcine respiratory tract, which was modified to mimic the mechanical properties of fibrotic lung parenchyma - i.e. reduced compliance. Passive respiratory mechanics were measured. 81m Kr scintigraphies were used to assess the homogeneity of gas-ventilation, while regional aerosol deposition was assessed with 99m Tc-DTPA scintigraphies. We validated the procedure to induce modifications of lung parenchyma to obtain aimed variation of compliance. Compared to the healthy model, lung respiratory mechanics were modified to the same extent as IPF-suffering patients. 81m Kr gas-ventilation and 99m Tc-DTPA regional aerosol deposition showed results comparable to clinical studies, qualitatively. This ex vivo respiratory model could simulate lung fibrosis for aerosol regional deposition studies giving an interesting alternative to animal experiments, accelerating and facilitating preclinical studies before clinical trials.

Introduction: The evaluation of the measured Glomerular Filtration Rate (mGFR) or estimated Glomerular Filtration Rate (eGFR) is key in the proper assessment of the renal function of potential kidney donors. We aim to study the correlation between glomerular filtration rate estimation equations and the measured methods for determining renal function., Material and Methods: We analysed the relationship between baseline GFR values measured by Tc- 99 m-DTPA (diethylene-triamine-pentaacetate) and those estimated by the four-variable Modification of Diet in Renal Disease (MDRD4) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations in a series of living donors at our institution., Results: We included 64 donors (70.6% females; mean age 48.3±11 years). Baseline creatinine was 0.8±0.1 mg/dl and it was 1.1±0.2 mg/dl one year after donation. The equations underestimated GFR when measured by Tc 99 m-DTPA (MDRD4-9.4 ± 25ml/min, P<.05, and CKD-EPI-4.4 ± 21ml/min). The correlation between estimation equations and the measured method was superior for CKD-EPI (r=.41; P<.004) than for MDRD4 (r=.27; P<.05). eGFR decreased to 59.6±11 (MDRD4) and 66.2±14ml/min (CKD-EPI) one year after donation. This means a mean eGFR reduction of 28.2±16.7 ml/min (MDRD4) and 27.31±14.4 ml/min (CKD-EPI) at one year., Conclusions: In our experience, CKD-EPI is the equation that better correlates with mGFR-Tc 99 m-DTPA when assessing renal function for donor screening purposes., (Copyright © 2017 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.)

(99m)Tc-DTPA has been used as a conservative tracer to quantify water transport through porous media. However, more information on the reactivity of this (99m)Tc compound under varying geochemical conditions is desirable to better understand its potential uses. We measured the speciation of Tc following amendment of (99m)Tc-DTPA to batch systems spanning a range of controlled biogeochemical conditions. Our results suggest that (99m)Tc-DTPA is stable under the reducing conditions tested. However, freshly precipitated Al-ferrihydrite may displace Tc(IV) from DTPA in the absence of Fe(III)-reducing conditions., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The optical properties of a receptor-targeted probe designed for dual-modality mapping of the sentinel lymph node (SLN) was optimized. Specific fluorescence brightness was used as the design criterion, which was defined as the fluorescence brightness per mole of the contrast agent. Adjusting the molar ratio of the coupling reactants, IRDye 800CW-NHS-ester and tilmanocept, enabled us to control the number of fluorescent molecules attached to each tilmanocept, which was quantified by H1 nuclear magnetic resonance spectroscopy. Quantum yields and molar absorptivities were measured for unconjugated IRDye 800CW and IRDye 800CW-tilmanocept (800CW-tilmanocept) preparations at 0.7, 1.5, 2.3, 2.9, and 3.8 dyes per tilmanocept. Specific fluorescence brightness was calculated by multiplication of the quantum yield by the molar absorptivity and the number of dyes per tilmanocept. It predicted that the preparation with 2.3 dyes per tilmanocept would exhibit the brightest signal, which was confirmed by fluorescence intensity measurements using three optical imaging systems. When radiolabeled with Ga68 and injected into the footpads of mice, the probe identified SLNs by both fluorescence and positron emission tomography (PET) while maintaining high percent extraction by the SLN. These studies demonstrated the feasibility of 800CW-tilmanocept for multimodal SLN mapping via fluorescence and PET-computed tomography imaging.

We demonstrate the utility of nuclear medical imaging technologies and a readily available radiotracer, [(99m)Tc]TcO(4)(-), for the noninvasive monitoring of Fe(II) production in acetate-stimulated sediments from Old Rifle, CO, USA. Microcosms consisting of sediment in artificial groundwater media amended with acetate were probed by repeated injection of radiotracer over three weeks. Gamma camera imaging was used to noninvasively quantify the rate and extent of [(99m)Tc]TcO(4)(-) partitioning from solution to sediment. Aqueous Fe(II) and sediment-associated Fe(II) were also measured and correlated with the observed tracer behavior. For each injection of tracer, curves of (99m)Tc concentration in solution vs time were fitted to an analytic function that accounts for both the observed rate of sedimentation as well as the rate of (99m)Tc association with the sediment. The rate and extent of (99m)Tc association with the biostimulated sediment correlated well with the production of Fe(II), and a mechanism of [(99m)Tc]TcO(4)(-) reduction via reaction with surface-bound Fe(II) to form an immobile Tc(IV) species was inferred. After three weeks of bioreduction, a subset of microcosms was aerated in order to reoxidize the Fe(II) to Fe(III), which also destroyed the affinity of the [(99m)Tc]TcO(4)(-) for the sediments. However, within 3 days postoxidation, the rate of Tc(VII) reduction was faster than immediately before oxidation implying a rapid return to more extensive bioreduction. Furthermore, aeration soon after a tracer injection showed that sediment-bound Tc(IV) is rapidly resolubilized to Tc(VII). In contrast to the [(99m)Tc]TcO(4)(-), a second commercially available tracer, (99m)Tc-DTPA (diethylenetriaminepentaacetic acid), had minimal association with sediment in both controls and biostimulated sediments. These experiments show the promise of [(99m)Tc]TcO(4)(-) and (99m)Tc-DTPA as noninvasive imaging probes for a redox-sensitive radiotracer and a conservative flow tracer, respectively.

Air sampling performed during 190 Tc-labeled DTPA aerosol lung ventilation studies indicated that the maximum airborne concentration to which the nuclear medicine technologists might be exposed was 7.1 x 10(-1) Bq mL(-1) (1.9 x 10(-5) microCi mL(-1)). If a single technologist performed ALL the aerosol studies, at this maximum airborne concentration, based on the Annual Limit on Intake (ALI), the resulting dose equivalents could be either 1 mSv (100 mrem) to the lungs or 0.1 mSv (10 mrem) to the total body. However, the procedures are shared by the technical staff, the times of exposure are represented by only a fraction of the overall procedure time, and the average airborne concentrations were found to be more than an order of magnitude lower than the maximum. This resulted in a projected average annual dose equivalent of 7.0 x 10(-3) mSv (0.7 mrem) to the lungs or 7.0 x 10(-4) mSv (0.07 mrem) to the whole body from the performance of these procedures.

The aim of this study was to reduce airborne contamination resulting from the use of aerosols in lung ventilation scintigraphy. Lung ventilation imaging is frequently performed with 99mTc-diethylenetriaminepentaacetate aerosol (DTPA), derived from a commercial nebuliser. Airborne contamination is a significant problem with this procedure; it results in exposure of staff to radiation and can reduce gamma camera performance when the ventilation is performed in the camera room. We examined the level of airborne contamination resulting from the standard technique with one of the most popular nebuliser kits and tested a modification which significantly reduced airborne contamination. Air contamination was measured while ventilating 122 patients. The modified technique reduced air contamination by a mean value of 64% (p = 0.028) compared with the standard control technique. Additionally, differences in contamination were examined when a mask or mouthpiece was used as well as differences between operators. A simplified method of monitoring air contamination is presented using a commonly available surface contamination monitor. The index so derived was proportional to air contamination (r = 0.88). The problems and regulations associated with airborne contamination are discussed.

Unlabelled: Contamination of working areas by 99mTc DTPA aerosol is of concern to nuclear medicine technologists. This study sought to determine the extent of 99mTc DTPA contamination to technologists, and to localize sources of aerosol leakage so that methods could be identified that would minimize contamination., Methods: Fifty to eighty millicuries 99mTc DTPA, diluted to a volume of 4-5 ml with normal saline, were injected into the nebulizing chamber of two commercially available inhalation aerosol systems. The patient's nostrils were clamped and a damp washcloth was wrapped around the patient's mouth. An alcohol swab was placed in the exit port of the exhaust filter in each delivery system, and the technologist involved wore a face mask during the inhalation phase. The patient breathed DTPA-labeled aerosol by mouth until the counting rate in the lungs was four times greater than the counting rate from the pulmonary perfusion phase. Connecting joints of the delivery system were then wipe tested. Last, a Geiger-Mueller detector (pancake probe) was used to survey all device components. Readings above 0.05 mR/hr were considered contaminated., Results: The patient was the greatest source of leakage as determined by the damp washcloth, followed by the joints of the tubes of the delivery system and, finally, the system's exhaust filter. Contamination readings from face masks worn by technical personnel during the lung ventilation studies were slightly greater than 0.05 mR/hr., Conclusion: The findings support trace levels of contamination to both the technologist and room while performing 99mTc DTPA aerosol ventilation studies. Comparative data using the two delivery systems revealed little difference in sources of leakage and little variation in contamination measurements.

To determine the percentage of liquid gastric contents experimentally removable by available orogastric lavage systems, five healthy young volunteers were asked to ingest 1 mCi of liquid technicium-99m diethylenetriaminepentaacetic acid (Tc99m-DTPA) mixed with 50 ml tap water. Five minutes afterwards, the radionuclide was lavaged using one of three different techniques-a single syringe method, a closed gravity drainage system, and a closed double syringe method--while continuous radioisotope camera images were taken. Control images, with no lavage performed, were also taken. All of the orogastric lavage methods removed a mean of between 80% and 85% of the stomach contents. The double syringe method was the quickest, while the single syringe method was least tolerated. When compared with control, none of the lavage techniques pushed gastric contents into the duodenum. Thus, in terms of amount of liquid gastric contents removed, there was no one method that removed more than the others. Caution should be exercised in assuming that 80-85% of a liquid gastric ingestion can be removed by lavage in the uncontrolled clinical setting. The use of any orogastric lavage for ingestion evacuation should be undertaken knowing that it is a morbid procedure and usually not necessary.

1. The radioaerosol 99mTc-DTPA produced by jet and ultrasonic nebulizers was characterized by measuring the median mass diameter (MMD) and geometric standard deviation (sigma g) and these characteristics were interpreted in terms of the aerodynamic principles of inertial impactation. 2. Jet nebulizers of the same model, with different outflows (NSA = 0.14 ml/min; NSB = 0.24 ml/min and NSC = 0.40 ml/min) showed different radioaerosol mass distribution, with MMD (NSC) > MMD (NSA). The ultrasonic nebulizer US-1000 from Narcosul, which is operated with an air flow of 2 l/min and frequency of 1.6 MHz, generated radioaerosol with MMD = 2.40 microns, higher than that obtained with most of the jet nebulizers evaluated (NSA = 1.50 microns; NSB1V = 1.40 microns; NSB2V = 1.20 microns and PITT#1 - 0.80 microns), and the ultrasonic nebulizer presented the highest outflow of the nebulized solution (1.15 ml/min). 3. Connecting one or two impactation reservoirs to the NSB jet nebulizer modified the mass distribution, which became significantly narrower for NSB2V when compared to the other two nebulizers. NSB2V presented a mass percentage with a diameter of 3 microns or less and a sufficient outflow for use in ventilation and pulmonary permeability studies. 4. Comparison of the mass collected in the cascade impactor and the total mass generated by the NSB, NSB1V and NSB2V nebulizers showed, on average, 4.5% efficiency in radioaerosol generation with a diameter of less than 16 microns and 3.2% efficiency for a diameter of 3 microns or less.