Aiming to obtain hybrid magneto-plasmonic nanostructures, we have developed multisegmented and core/shell structured Fe-Au nanorods using template assisted electrochemical deposition. A facile method of tuning the growth pattern of multisegmented nanorods into core/shell structured is demonstrated. With a precise control of current density and deposition time, a brick-stacked wire like growth led to the formation of hollow nanotubes that could be further tuned to multilayered hollow nanotubes and core/shell structured nanorods. TEM imaging and STEM-EELS technique were used to explore the morphology, microstructure and the distribution of Au and Fe in the nanorods. The easy magnetization direction was found to be perpendicular to the nanorods' growth direction in the segmented nanorods. On the other hand, core/shell nanorods exhibited isotropic behavior. Our findings provide deeper insights into the fabrication of hybrid nanorods and the opportunity to tune the fabrication method to vary their morphology accordingly. Such studies will benefit design of hybrid nanorods with specific morphologies and physical properties and hence their integration into sensing, spintronics and other potential biomedical and technological applications.

The results of studies of the properties of co-deposition of magnetic nanoparticles (MNPs) of Co1-xZnxFe2O4 spinel ferrites synthesized (at x=0.0; 0.1; 0.2; 0.4; 0.6) in order to create magnetic particles for biomedicine. X-ray diffraction (RD), raman scattering of light, magnetic measurements and Mossbauer spectroscopy (MS) were used to study the obtained Co1-xZnxFe2O4 MNPs. It was found that the synthesized MNCs CoxZn1-xFe2O4 are single-phase. According to the results of RD measurements, it was found that the average sizes of crystallites are 13 nm for CoFe2O4 (x=0) and, with an increase in the Zn concentration, they decrease to 7 nm for Co1-xZnxFe2O4 (x=0.6), which is consistent with the Mössbauer data, which showed that the sizes of crystallites vary from 14 to 8 nm. In the raman spectra of the Co1-xZnxFe2O4 MNF in the region of ~620 cm-1, splitting of the A1g line is observed, indicating that the studied particles have an inverse spinel structure. Changing the ratio of peak intensities A1g

Cobalt oxide, nickel oxide and cobalt/nickel binary oxides were synthesised by electrodeposition. To fine tune composition of CoNi alloys, growth parameters including voltage, electrolyte pH/concentration and deposition time were varied. These produced nanomaterials were used as binder free electrodes in supercapacitor cells and tested using three electrode setup in 2 MKOH aqueous electrolyte. Cyclic voltammetry and galvanostatic charge/discharge were used at different scan rates (5–100 mV/s) and current densities (1–10 A/g) respectively to investigate the capacitive behaviour and measure the capacitance of active material. Electrochemical impedance spectroscopy was used to analyse the resistive/conductive behaviours of these electrodes in frequency range of 100 kHz to 0.01 Hz at applied voltage of 10 mV. Binary oxide electrode displayed superior electrochemical performance with the specific capacitance of 176 F/g at current density of 1 A/g. This hybrid electrode also displayed capacitance retention of over 83% after 5000 charge/discharge cycles. Cell displayed low solution resistance of 0.35 Ω along with good conductivity. The proposed facile approach to synthesise binder free blended metal electrodes can result in enhanced redox activity of pseudocapacitive materials. Consequently, fine tuning of these materials by controlling the cobalt and nickel contents can assist in broadening their applications in electrochemical energy storage in general and in supercapacitors in particular.

The results of studies of the properties of co-deposition of magnetic nanoparticles (MNPs) of Co 1-x Zn x Fe 2 O 4 spinel ferrites synthesized (at x=0.0; 0.1; 0.2; 0.4; 0.6) in order to synthesize magnetic particles for biomedical applications. X-ray diffraction (XRD), raman spectra, magnetic measurements and Mossbauer spectroscopy (MS) were used to study the Co 1-x Zn x Fe 2 O 4 MNPs. It was found that the synthesized MNPs Co x Zn 1-x Fe 2 O 4 are single-phase. According to the results of XRD measurements, it was found that the average sizes of crystallites are 13 nm for CoFe 2 O 4 (x=0) and, with an increase in the Zn concentration, they decrease to 7 nm for Co 1-x Zn x Fe 2 O 4 (x=0.6), which is consistent with the Mossbauer data, which showed that the sizes of crystallites vary from 14 to 8 nm. In the raman spectra of the Co 1-x Zn x Fe 2 O 4 MNPs in the region of ~620 cm -1 , splitting of the A 1g , line is observed, indicating that the studied particles have an inverse spinel structure. The change in the ratio between intensities of A 1g (1) and A 1g (2) peaks is indicative of a significant redistribution of Co 2+ and Fe 3+ cations between tetrahedral andoctahedral positions in Co 1-x Zn x Fe 2 O 4 MNPs as the quantity of Zn increases, which is confirmed by the Mossbauer data. It is found that small sizes of MNPs result in a strengthening of the effects of size and an effect of surface on the magnetic structure of the surface layer. The MS analysis has shown that there is a layer on the MNP surface, the magnetic structure of which is different from from the structure of the crystallite volume. With increase in the quantity of Zn ions thickness of this layer increases and at x=0.6 the particle becomes completely paramagnetic. Mossbauer studies have shown that Co 0.8 Zn 0.2 Fe 2 O 4 (x=0.2) particles are inthe superparamagnetic state and theirmagnetic blocking temperature is ~315 K, which is the most acceptable for the treatment of cancer by the magnetic hyperthermia method. Keywords: Co x Mn 1-x Fe 2 O 4 , spinel ferrites, magnetic structure, superparamagnetism, Mossbauer spectroscopy, materials for biomedicine.

Magnetic nanoparticles (NP) of ferrite Co0.8-xMnxZn0.2Fe2O4 (x=0.6, 0.4 and 0.2) were synthesized by co-deposition. The structural, microstructural, magnetic and ultrathin properties of the obtained particles were investigated by X-ray diffraction and Mössbauer spectroscopy. The nanoparticle sizes calculated from radiographs at x=0.6, 0.4 and 0.2 are 15.2, 10.2 and 10.3 nm, respectively. The influence of the amount of Mn ions introduced on the properties of synthesized particles has been studied. The analysis of experimental Mossbauer spectra showed that the small size of the LF leads to a significant increase in the effects of dimensionality and the influence of the surface on the magnetic structure of the surface layer. The Mossbauer studies, for the first time without the use of external magnetic fields, on the example of MNCH spinel ferrites Co0.8-xMnxZn0.2Fe2O4, found that inside the particle the magnetic moments are ordered collinearly, whereas in the surface layer the moments are oriented at an angle to each other (beveled structure).

Изучены свойства магнитных наночастиц (МНЧ) ферритов-шпинелей CoxMn1-xFe2O4 (при x=0.0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1.0), синтезированых методом химического соосаждения. Исследования синтезированных МНЧ CoxMn1-xFe2O4 проведены с использованием рентгеновской дифракции (РД), комбинационного рассеяния света и мёссбауэровская спектроскопия. Результаты РД, рамановских и мёссбауэровских исследований указывают, что полученные МНЧ CoxMn1-xFe2O4 являются однофазным. Из РД измерений установлено, что средние размеры кристаллитов CoxMn1-xFe2O4 составляют 34.86 nm для MnFe2O4 (x=0) и при повышении концентрации Co уменьшаются до 14.99 nm для CoFe2O4 (x=1.0). Анализ мессбауровских спектров показал, что средние размеры кристаллитов меняются от 25 nm для MnFe2O4 (x=0) до 12 nm для CoFe2O4 (x=1.0). На спектрах комбинационного рассеяния МНЧ CoxMn1-xFe2O4, в области ~620 cm-1 наблюдается расщепление линии A1g, это означает, что исследуемые МНЧ обладают структурой обратной шпинели. Соотношение интенсивностей пиков A1g (1) и A1g (2) указывает на значительное перераспределение катионов Co2+ и Fe3+ между тетра- и октаэдрическими позициями в МНЧ феррита CoxMn1-xFe2O4, что подтверждается мессбауэровскими данными. Данные мёссбауровсой спектроскопии указывают, что синтезированные МНЧ CoxMn1-xFe2O4 состоят из крупных частиц, обладающих магнитным упорядочением, и мелких частиц находящихся в парамагнитной фазе. С повышением концентрации ионов Mn доля мелких частиц возрастает, что приводит к понижению температуры магнитного блокироввания. Намагниченность насыщения МНЧ при x=0.2 (Co0.2Mn0.8Fe2O4) составляет 57.41 emu/g и этот образец, как было установлено в [V. Narayanaswamy, I.A. Al-Omari, A.S. Kamzin, B. Issa, H.O. Tekin, H. Khourshid, H. Kumar, A. Mallya, S. Sambasivam, I.M. Obaidat. Nanomaterials 11, 1231 (2021)] имеет наибольшее значение удельной скорости поглощения. Как показали мессбауэровские исследования, это связано с тем, что эти частицы находятся в суперпарамагнитном состоянии и температура магнитной блокировки этих МНЧ находится в области ~315 K, наиболее приемлемой для лечения злокачественных опухолей методом магнитной гипертермии. Таким образом, синтезированные МНЧ CoxMn1-xFe2O4 являются перспективными для биомедицинских применений. Ключевые слова: ферриты-шпинели CoxMn1-xFe2O4, магнитная структура, суперпарамагнетимз, мёссбауэровская спектроскопия, материалы для биомедицины.

The properties of magnetic nanoparticles (MNPs) of spinel ferrites CoxMn1-xFe2O4 (at x=0.0; 0.2; 0.3; 0.4; 0.5; 0.6; 0.8; 1.0) synthesized by chemical co-precipitation method have been studied. The studies of the synthesized CoxMn1-xFe2O4 MNPs were carried out using X-ray diffraction (XRD), Raman scattering and Mossbauer spectroscopy. The results of XRD, Raman and Mossbaur studies indicate that the obtained CoxMn1-xFe2O4 MNPs are single-phase. It was established from XRD measurements that the average size of CoxMn1-xFe2O4 crystallites is 34.86 nm for MnFe2O4 (x=0) and decreases to 14.99 nm for CoFe2O4 (x=1.0) with increasing Co ions concentration. An analysis of the Mossbaur spectra showed that the average crystallite size varies from 25 nm for MnFe2O4 (x=0) to 12 nm for CoFe2O4 (x=1.0). On the Raman spectra of CoxMn1-xFe2O4 MNPs, in the region of ~620 cm-1, splitting of the A1g line is observed, which means that the studied MNPs have a reverse spinel structure. The intensity ratio of the A1g (1) and A1g (2) peaks indicates a significant redistribution of the Co2+ and Fe3+ cations between tetra- and octahedralpositions in MNPs of the CoxMn1-xFe2O4 ferrite, which is confirmed by Mossbauer data. Mossbaur spectroscopy data indicate that the synthesized CoxMn1-xFe2O4 MNPs consist of large particles with magnetic ordering and small particles in the paramagnetic phase. With an increase in the concentration of Mn ions, the proportion of fine particles increases, which leads to a decrease in the magnetic blocking temperature. The saturation magnetization of MNPs at x=0.2 (Co0.2Mn0.8Fe2O4) is 57.41 emu/g and this sample, as was found in [V. Narayanaswamy, I.A. Al-Omari, A.S. Kamzin, B. Issa, H.O. Tekin, H. Khourshid, H. Kumar, A. Mallya, S. Sambasivam, I.M. Obaidat. Nanomaterials 11, 1231 (2021)] has the highest specific absorption rate. As shown by Mossbauer studies, this is due to the fact that these particles are in a superparamagnetic state and the magnetic blocking temperature of these MNPs is in the region of ~315 K, which is most suitable for the treatment of malignant tumors by magnetic hyperthermia. Thus, the synthesized CoxMn1-xFe2O4 MNPs are promising for biomedical applications. Keywords: spinel ferrites CoxMn1-xFe2O4, magnetic structure, superparamagnetism, Mossbauer spectroscopy, materials for biomedicine.

Cobalt nanowires have been synthesized by electrochemical deposition using track-etched anodized aluminum oxide (AAO) templates. Nanowires with varying spacing-to-diameter ratios were prepared, and their magnetic properties were investigated. It is found that the nanowires’ easy magnetization direction switches from parallel to perpendicular to the nanowire growth direction when the nanowire’s spacing-to-diameter ratio is reduced below 0.7, or when the nanowires’ packing density is increased above 5%. Upon further reduction in the spacing-to-diameter ratio, nanowires’ magnetic properties exhibit an isotropic behavior. Apart from shape anisotropy, strong dipolar interactions among nanowires facilitate additional uniaxial anisotropy, favoring an easy magnetization direction perpendicular to their growth direction. The magnetic interactions among the nanowires were studied using the standard method of remanence curves. The demagnetization curves and Delta m (Δm) plots showed that the nanowires interact via dipolar interactions that act as an additional uniaxial anisotropy favoring an easy magnetization direction perpendicular to the nanowire growth direction. The broadening of the dipolar component of Δm plots indicate an increase in the switching field distribution with the increase in the nanowires’ diameter. Our findings provide an important insight into the magnetic behavior of cobalt nanowires, meaning that it is crucial to design them according to the specific requirements for the application purposes.

INTRODUCTION:This study aimed to investigate the response of the radiology workforce to the impact of the coronavirus disease 2019 (COVID-19) pandemic on professional practice in India and eight other Middle Eastern and North African countries. It further investigated the levels of fear and anxiety among this workforce during the pandemic.METHODS:A quantitative cross-sectional study was conducted using an online survey from 22 May-2 June 2020 among radiology workers employed during the COVID-19 pandemic. The survey collected information related to the following themes: (1) demographic characteristics, (2) the impact of COVID-19 on radiology practice, and (3) fear and (4) anxiety emanating from the global pandemic.RESULTS:We received 903 responses. Fifty-eight percent had completed training on infection control required for handling COVID-19 patients. A large proportion (79.5%) of the respondents strongly agreed or agreed that personal protective equipment (PPE) was adequately available at work during the pandemic. The respondents reported experiences of work-related stress (42.9%), high COVID-19 fear score (83.3%) and anxiety (10%) during the study period.CONCLUSION:There was a perceived workload increase in general x-ray and Computed Tomography imaging procedures because they were the key modalities for the initial and follow-up investigations of COVID-19. However, there was adequate availability of PPE during the study period. Most radiology workers were afraid of being infected with the virus. Fear was predominant among workers younger than 30 years of age and also in temporary staff. Anxiety occurred completely independent of gender, age, experience, country, place of work, and work status.IMPLICATIONS FOR PRACTICE:It is important to provide training and regular mental health support and evaluations for healthcare professionals, including radiology workers, during similar future pandemics.

In this paper, we report a one-pot chemical synthesis technique for the preparation of iron and iron-carbide nanoparticles. Mössbauer spectroscopy, X-ray diffraction and magnetometry were used as the main tools to identify the different phases of Fe-C present. The influence of experimental parameters on the structural and compositional properties of nanoparticles was investigated in detail. These particles show ferromagnetic behavior with room temperature coercivity higher than 300 Oe. The X-ray diffraction was complemented by Mössbauer spectroscopy and thermo-magnetic analysis. Remarkably, the carbon content in iron-carbide nanoparticles (carbon rich or carbon poor iron-carbides) can be modulated simply by varying the experimental conditions, like the reaction time, temperature and iron precursor concentration. Magnetic properties can be tailored based upon crystallographic structure and particles composition.

Blocking temperatures of aggregates of Mn0.5Zn0.5GdxFe(2-x)O4 ferrite nanoparticles, with x = 0.02, 0.05, 0.11, 0.15, and 0.2, were obtained from the zero-field-cooled (ZFC) magnetization measurements. We found a nonmontonic behavior of the blocking temperature with increasing size of the particles. The effective magnetic anisotropy was calculated and found to have two distinct rates of increase with decreasing the size of the particles. These results were attributed to the strong inter-particle interactions in the aggregated nanoparticles and to the enhanced role of surface anisotropy with the decrease of the size of the particles. In three samples, the ZFC magnetization was found to exhibit a significant negative magnetization in a considerable part of the low temperature region. To our knowledge, this is the first time that negative magnetization is reported in such nanoparticles. These peculiar results are discussed and are currently under investigation.

The influence of temperature on coercivity, Hc and saturation magnetization, Ms were investigated experimentally in Mn0.5Zn0.5Gd0.02Fe1.98O4 ferrite nanoparticles (average size 35 nm). Isothermal magnetization curves M (H) were obtained in the field range from -5 kOe to +5 kOe at different temperatures after the zero field cooling (ZFC) process. The temperature dependence of the coercivity, Hc(T) deviated slightly from the classical Kneller's law. The temperature dependence of saturation magnetization, Ms(T) was found to have an excellent agreement with the Bloch's law. These results are discussed in terms of several factors such as the size and size distribution of the particles, inter-particle interactions and the surface spin.

We have studied the magnetic properties of aggregates of Mn0.5Zn0.5Gd(x)Fe(2-x)O4 ferrite nanoparticles, with x = 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.18, 0.20. The scanning electron microscopy micrographs show significant aggregation of the nanoparticles in all samples. Zero field cooled and field cooled magnetization measurements were conducted on all samples from 400 K down to 5 K. Most zero field cooled curves were found to exhibit the usual behavior but with wide peaked regions. For some x values, the field cooled magnetization was found to increase slowly with decreasing temperature, and becomes nearly constant at low temperatures. The measurements of magnetization versus applied magnetic field were conducted on all samples at 5 K and 305 K in the field range from -15000 to 15000 Oe. At 305 K the magnetization for all samples was observed to saturate, while at 5 K the magnetization did not reach saturation for some values of x. The saturation magnetization values were suggested to be proportional to the size of particles. These results were discussed and suggested to be due to the inter-particle dipolar and exchange interactions between the particles in the aggregates, the large particle size distribution and the surface magnetization effects.

Introduction: Recent technical advances have made available magnetic nanoparticles (MNPs) of different compositions, coating, sizes, and size distributions leading to different chemical and physical properties and a range of applications (e.g. molecular imaging). We studied the 1/T1 and 1/T2 behaviour with MNP concentration and also explored the effect of the coating for a new class of MNPs composed of elements Zn, Mn, Gd and iron oxides. These particles have already been used as hyperthermia agents and are being considered as MRI contrast agents. Material & Methods: Nanoparticles Synthesis: Various samples of Gd substituted Mn-Zn Ferrite nanoparticles were synthesized using a chemical coprecipitation method and ferritization. In this method a 0.1 M solution of the metal salts MnCl2, FeCl3, FeSO4, ZnSO4 and GdCl3 was added to an 8 M solution of NaOH. The mixture was stirred vigorously at 90oC for 40 minutes followed by filtration, washing, and drying. Samples made were of the form Mn0.5Zn0.5GdxFe(2-x)O4 with x = 0.02. MNPs were dispersed in viscous solution (agarose gel) followed by ultrasonication to ensure homogeneous distribution. A range of concentrations C (in mM of MNPs) was prepared from C = 0.0 to 0.3 mM for both naked and PEG-coated MNPs. MR Relaxometry: Measurement of T1 and T2 was performed (at 1.5 T) using a GE SIGNA MR Scanner (Twin Gradient Echo Speed, General Electric, Milwaukee, WI, USA). A fast spin-echo (FSE) imaging sequence was used with the following parameters: FOV 20 cm, 256 x 256, NEX = 1, slice = 5 mm, Echo Train Length = 16, BW = 15.63 kHz, flip = 90. For the T1 measurement an inversion recovery FSE sequence was used with TE = 15 ms and TR = 6s, and eight values for the inversion time: 50 4000 ms. T2-weighted images were generated using seven values of TE: 12 152 ms. Mean signal values were then fitted to a single exponential curve. Results: The magnetic moment (μ) was measured to be 13.07 EMU/g at 27C. ICP measurements gave the following concentrations (μg/mL): Gd 60, Mn 810, Fe 1874, and Zn 511. Figure 1 below shows SEM images of uncoated MNPs. The average diameter for the uncoated and coated MNPs were 36 and 63 nm, respectively, as determined automatically by image processing software. The coating affects not only the particle size and size distribution, but also agglomeration properties of the particles. 1/T1 and 1/T2 are plotted as a function of concentration in Figure 2. The 1/T2 relaxation mechanism is the classical outer-sphere relaxation enhancement by diffusion through field gradients created by MNPs [1,2]. The increase of R1 and R2 with MNPs concentration is larger for the uncoated particles than for the coated ones. This can be explained by the larger distance separating the gel protons from the nanoparticles in the coated case. Any disagreement between theoretical (1/T2=16 ν Δω τD/45; ν is the volume fraction occupied by the MNPs, Δω is the angular frequency at the equatorial line of the MNP, τD is the time taken by protons to diffuse a distance similar to MNP radius) and experimental results can be due to the agglomeration of the particles, which effectively increases the particle size, and the distribution of sizes. For the PEG-coated particles we have also calculated the theoretical 1/T2 using a reduced radius since water molecules diffuse through the PEG layer. The dotted line shows a better agreement between theoretical and experimental results when the effective radius is reduced to 80% of the true radius.

In this study, the magnetic properties of Mn0.5Zn0.5GdxFe(2-x)O4 nanoparticles, with x = 0, 0.2, 0.5, 1.0, 1.5 were studied. The magnetization was found to increase with the initial increase of the size of the particles followed by a sharp decrease with further increase of the size of the particles. The magnetization of the particles was found to remain nearly constant at temperatures below 50 K above which, the magnetization was found to exhibit peaked region. The existence of such peaked regions was considered to be a signature of surface spin-glass structures. At high temperatures, the magnetization was found to decrease sharply. For some x values, the magnetization displayed a small and smooth decrease below 50 K.

Due to recent fast technical developments and the ever increasing demands for better health services and living standards, increasing demands are witnessed for a larger number of better qualified medical physicists. Pressures are mounting on educational institutes to come up with the appropriate balance among background teaching material, skills, and practical training. The widening spectrum of new teaching courses possible for addition to the university curriculum presents a non-trivial program structure problem. In addition to more financial and hardware demands, it requires careful tailoring of the educational process (teaching material and skills, timing and delivery methods, program structure) according to the particular goals of the program and the professional needs of the geographic location. We highlight some of the difficulties experienced locally in both medical physics (MP) education and profession and compare them with various regions of the globe. Finally, we propose some suggestions to alleviate them. In particular we emphasize the importance of acquiring programming skills at an early stage of the educational process. This is so not only because it is a skill, but also because it can be developed into a teaching tool itself through the solving of many MP problems by modeling and simulation.

Room-temperature magnetization hysterisis measurements were conducted on Mn0.5Zn0.5Gd Fe(2-x)O4 ferrite nanoparticles, with x = 0, 0.5, 1.0, 1.5. The structure of this ferrite is normal spinel where the added of Gd3+ ions occupied the octahedral sites and replaces Fe3+ ions. The saturation magnetization was found to increase with the initial addition of the Gd3+ ions followed by a sharp decrease with further addition of Gd3+ ions. The Curie temperature was found to increase up to Gd3+ concentration of x = 1.0, and then decreases at x = 1.5. These results were attributed to the surface sTins. Because the size of Gd3+ ions is larger than that of Fe3+ ions, the substitution of Fe ions with the Gd3+ ions results in surface disorder which results in surface spins. A core-shell magnetization model was introduced where several factors were combined to explain our results. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhem

It is known now that an increase in tumor temperature decreases the tumor resistance to chemo‐ and radiation therapies. Hyperthermia treatment of the tumor cells where damage to the healthy cells can be avoided is viable by using magnetic nanoparticles with controlled Curie temperatures. Nickel‐Chromium (Ni1‐x Crx) particles with varying compositions have been investigated as thermoseeds for use in localized self controlled hyperthermia treatment of cancer. A series of Ni1‐x Crx alloys, have been prepared to find the specific composition which has Curie temperature around 316‐317 K. The samples were cast by arc melting technique, and were annealed at 850 oC for 5 hours in sealed quartz tubes. Magnetic properties of the samples were investigated, including Curie temperature, saturation magnetization and hysterisis using Superconducting Quantum Interference Device (SQUID) and Vibrating Sample Magnetometer (VSM). The Curie temperatures of the alloys were found to decrease almost linearly from 401 K to 289 K as the Cr concentration was increased from x = 4.54 wt% to x = 5.90 wt%. The results showed that Ni1‐x Crx alloys might be good candidates for self regulating magnetic hyperthermia applications. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Purpose: To evaluate and compare the reproducibility of the preferred phenomenological parameter IAUC(60) (initial area under the time-concentration curve [IAUC] defined over the first 60 seconds postenhancement) with the preferred modeling parameter as derived using two simple models, in abdominal and cerebral data collected in typical Phase I clinical trial conditions.Materials and Methods: Dynamic contrast enhanced MRI (DCE-MRI) time series were acquired at two imaging centers from a group of patients with abdominal tumors and a group with gliomas. At both imaging centers, precontrast T-1 was calculated using a variable flip angle three-dimensional spoiled gradient echo acquisition that was used to quantify tissue contrast agent concentration. allowing voxelwise definition of summary DCE-MRI parameters.Results: A comparison of reproducibility showed that there was no statistically significant difference in reproducibility between IAUC(60) and K-trans, although there was a trend towards better reproducibility for W,an, (p = 0.0782). The 95% confidence intervals (CIs) for individual changes showed that for IAUC(60) and K-trans, changes in excess of 47% and 31%, respectively. are outside the range of normal variability.Conclusion: Although modeling is more complex and more computationally intensive than an IAUC parameterization, our data suggest this approach to be preferable to a model-free approach since it provides greater physiological insight without a reduction in statistical power for Phase I/II clinical drug trials.