Synthesis of water-soluble FeOOH nanospindles and their performance for magnetic resonance imaging

Water soluble FeOOH nanospindles with small size were synthesized by a simple hydrolysis method of inorganic salts and water bath treatment with different incubation time. The morphology, microstructure, magnetic resonance imaging (MRI) performance and cytotoxicity of the as-prepared FeOOH nanospindles were investigated, respectively. The results showed that the longitudinal length of FeOOH nanospindles was about 40-50 nm, and the incubation time had important effect for the morphology and production rate of FeOOH nanospindles. MRI test showed that the longitudinal and transverse relaxivities (r₁ and r₂ values) of FeOOH nanospindles were about 3.06 mM⁻¹ s⁻¹ and 5.06 mM⁻¹ s⁻¹, respectively. Furthermore, the experimental results of the Prussian Blue staining showed the clusters of FeOOH nanospindles in the cytoplasm of the labeled cells, and the cytotoxicity characterization indicated that FeOOH nanospindles have low cytotoxicity. Therefore, the as-prepared FeOOH nanospindles will have potential applications as T₁- and T₂-weighted MRI contrast agents.     

Assessment of renal fibrosis in a rat model of unilateral ureteral obstruction with diffusion kurtosis imaging: Comparison with α-SMA expression and 18F-FDG PET

PurposeTo investigate the utility of diffusion kurtosis imaging (DKI) MRI for evaluation of renal fibrosis in rats with unilateral ureteral obstruction (UUO).MethodsTwenty-five rats had UUO, and ten rats were subjected to sham operation as control. DKI was performed on a 3.0 T MRI scanner on days 1, 3, 5, and 7 after ligation. All rats then underwent ¹⁸F-FDG dynamic PET to evaluate unilateral renal function, followed by histological analysis to examine α-smooth muscle actin (α-SMA) expression. DKI metrics were assessed among the time points and between two sides, and compared with maximum standardized uptake value (SUV_max), serum levels of creatinine and urea, and fibrosis marker α-SMA.ResultsMean kurtosis (MK) on day 7, axial kurtosis (Ka) on days 3 and 7, mean diffusivity (MD) on days 1, 3, 5, and 7, and fractional anisotropy (FA) on days 3, 5, and 7 of cortex and medulla between the UUO and contralateral sides were significantly different (all p < 0.05). Over the course of UUO progression, there were significant changes in Ka, MD and FA of medulla (all p < 0.05). FA of medulla was positively correlated with SUV_max (r = 0.641, p < 0.001), and MD of cortex was negatively correlated with urea (r = −0.534, p = 0.001). MD of cortex was negatively correlated with α-SMA on UUO sides (r = −0.710, p < 0.001).ConclusionsDKI shows the potential for noninvasive assessment of renal fibrosis and unilateral renal function induced by UUO.     

Novel S-Gal analogs as H MRI reporters for in vivo detection of β-galactosidase

The quantitative assessment of gene expression and related enzyme activity in vivo could be important for the characterization of gene altering diseases and therapy. The development of imaging techniques, based on specific reporter molecules may enable routine non-invasive assessment of enzyme activity and gene expression in vivo. We recently reported the use of commercially available S-Gal^® as a β-galactosidase reporter for ¹H MRI, and the synthesis of several S-Gal^® analogs with enhanced response to β-galactosidase activity. We have now compared these analogs in vitro and have identified the optimal analog, C3-GD, based on strong T₁ and T₂ response to enzyme presence (ΔR₁ and ΔR₂ ~ 1.8 times S-Gal^®). Moreover, application is demonstrated in vivo in human breast tumor xenografts. MRI studies in MCF7-lacZ tumors implanted subcutaneously in athymic nude mice (n = 6), showed significant reduction in T₁ and T₂ values (each ~ 13%) 2 h after intra-tumoral injection of C3-GD, whereas the MCF7 (wild type) tumors showed slight increase. Thus, C3-GD successfully detects β-galactosidase activity in vivo and shows promise as a lacZ gene ¹H MR reporter molecule.     

Histopathologically confirmed focal nodular hyperplasia of the liver: Gadoxetic acid-enhanced MRI characteristics

Purpose

The purpose of this study was to evaluate enhancement characteristics of histopathologically confirmed focal nodular hyperplasia (FNHs) with gadoxetic acid-enhanced MRI.

Materials and Methods

Twenty-seven patients with all histopathologically proven FNHs were retrospectively identified. MRI consisted of T₁- and T₂-weighted (w) sequences with and without fat saturation (FS), multiphase dynamic T₁-w images, and FS T₁-w images during the hepatobiliary phase. Standard of reference was surgical resection (n = 24) or biopsy (n = 3). Images were analyzed for morphology and contrast behavior including signal intensity (SI) measurement on T₁-w images normalized to the pre-contrast base line.

Results

In total 36 FNHs were evaluated. All FNHs showed enhancement in the arterial phase, significant reduction contrast enhancement (“wash-out”) in the late dynamic phases was not present. In the hepatobiliary phase, all FNHs (100%) showed enhancement (overall SI increase, 118% (± 91%), P < 0.001) with at least partial hyperintensity to the liver. Upon visual comparison, 3 of 36 FNHs appeared with heterogeneous/partial enhancement (8%) and 7 (19%) showed rim-accentuated enhancement.

Conclusion

The typical enhancement pattern of FNH with gadoxetic acid consists of arterial hyperperfusion, no wash-out during the venous phase, and at least partial hyperintensity compared to the liver in the hepatobiliary phase. Partial hypointensity or rim-accentuated enhancement rarely occurs.     

Assessment of T1, T1ρ, and T2 values of the ulnocarpal disc in healthy subjects at 3 tesla

Objective

The purpose of this study was to implement clinically feasible imaging techniques for determination of T₁, T_1ρ, and T₂ values of the ulnocarpal disc and to assess those values in a cohort of asymptomatic subjects at 3 tesla. Resulting values were compared between different age groups, since former histological findings of the ulnocarpal disc indicated frequent early degenerative changes of this tissue starting in the third decade of life, even in asymptomatic subjects.

Materials and methods

Twenty-seven healthy subjects were included in this study. T₁ measurements were performed using 3D spoiled gradient-echo (GRE) sequence with variable flip angle. A series of T_1ρ and T₂-weighted images was acquired by a 3D GRE sequence after suitable magnetization preparation. T_1,T_1ρ, and T₂ maps of the ulnocarpal disc were calculated pixel-wise. Representative mean values from extended regions were analysed.

Results

Mean T₁ values of the ulnocarpal disc ranged from 722 ms in a 39 year-old subject to 1264 ms in a 65 year-old subject, T_1ρ ranged from 9.2 ms (26 year-old subject) to 25.9 ms (65 year-old subject). Calculated T₂ values showed a large range from 4.1 ms to 22.3 ms. T_1ρ and T₁ values tended to increase with age (p < 0.05), whereas T₂ did not.

Conclusions

MR relaxometry of the ulnocarpal disc is feasible, and T_1,T_1ρ, and T₂ values show modest variance in asymptomatic subjects. The potential of relaxation mapping to reveal relevant structural changes in patients has to be investigated in further studies.     

Functional MRI Using Spin Lock Editing Preparation Pulses

A novel approach for detecting blood oxygenation level-dependent (BOLD) signals in the brain is investigated using spin locking (SL) pulses to selectively edit the effects of extravascular diffusion in field gradients from different sized vascular structures. We show that BOLD effects from diffusion amongst susceptibility gradients will contribute significantly not only to transverse relaxation rates (R₂* and R₂) but also to R_1ρ, the rate of longitudinal relaxation in the rotating frame. Similar to the ability of 180-degree pulses to refocus static dephasing effects in a spin echo, moderately strong SL pulses can also reduce contributions of diffusion in large-scale gradients and the choice of SL amplitude can be used to selectively emphasize smaller scale inhomogeneities (such as microvasculature) and to drastically reduce the influence of larger structures (such as veins). Moreover, measurements over a range of locking fields can be used to derive estimates of the spatial scales of intrinsic gradients. The method was used to detect BOLD activation in human visual cortex. Eight healthy young adults were imaged at 3 T using a single-slice, SL-prepped turbo spin echo (TSE) sequence with spin-lock amplitudes ω₁ = 80 Hz and 400 Hz, along with conventional T₂*-weighted and T₂-prepped sequences. The BOLD signal varied from 1.1 ± 0.4 % (ω₁ = 80 Hz) to 0.7 ± 0.2 % (at 400 Hz), whereas the T₂-weighted sequence measured 1.3 ± 0.3 % and the T₂* sequence measured 1.9 ± 0.3 %. This new R_1ρ functional contrast can be made selectively sensitive to intrinsic gradients of different spatial scales, thereby increasing the spatial specificity of the evoked response.     

Magnetic,optical and relaxometric properties of organically coated gold–magnetite (Au–Fe3O4) hybrid nanoparticles for potential use in biomedical applications

We present the magnetic, optical and relaxometric properties of multifunctional Au–Fe₃O₄ hybrid nanoparticles (HNPs), as possible novel contrast agents (CAs) for magnetic resonance imaging (MRI). The HNPs have been synthesized by wet chemical methods in heterodimer and core–shell geometries and capped with oleylamine. Structural characterization of the samples have been made by X-ray diffraction and transmission electron microscopy, while magnetic properties have been investigated by means of Superconducting Quantum Interference Device-SQUID magnetometry experiments. As required for MRI applications using negative CAs, the samples resulted superparamagnetic at room temperature and well above their blocking temperatures. Optical properties have been investigated by analyzing the optical absorbtion spectra collected in UV–visible region. Relaxometric measurements have been performed on organic suspensions of HNPs and Nuclear Magnetic Resonance (NMR) dispersion curves have been obtained by measuring the longitudinal 1/T₁ and transverse 1/T₂ relaxation rates of solvent protons in the range 10 kHz/300 MHz at room temperature. NMR relaxivities r₁ and r₂ have been compared with ENDOREM^®, one of the commercial superparamagnetic iron oxide based MRI contrast agents. MRI contrast enhancement efficiencies have been investigated also by examining T₂-weighted MR images of suspensions. The experimental results suggest that the nanoparticles' suspensions are good candidates as negative CAs.     

Manganese-enhanced magnetic resonance imaging investigation of the interferon-α model of depression in rats

Therapeutic effects of interferon-α (IFN-α) are known to be associated with CNS toxicity in humans, and in particular with depression symptoms. Animal models of IFN-α-induced depression (sickness behaviour) have been developed in rodents using various preparations, dosing schedules or routes of administrations. In this work, Manganese Enhanced MRI (MEMRI) has been applied to investigate an experimental model of sickness behaviour induced by administration of IFN-α in rats. IFN-α (3.10⁵ U/kg), or vehicle, was daily administered i.p., for 7 days in rats (n = 20 IFN-α treated and n = 20 controls). After treatment, animals were assigned to behavioural (n = 10 treated, n = 10 control) or MRI (n = 10 treated and n = 10 control) studies. Animals assigned to the MRI study received two repeated i.p. injections of MnCl₂, before image acquisition. Images were acquired at 4.7 T using T₁ mapping for determination of Mn concentration in brain. After co-registration of T₁ maps to a digital brain atlas, differences between brains of treated and untreated animals were assessed pixel-to-pixel by statistical analysis.     

MR T1ρ quantification of cartilage focal lesions in acutely injured knees: correlation with arthroscopic evaluation

Objective

Quantitative T₁ρ MRI has been suggested as a promising tool to detect changes in cartilage composition that are characteristic of cartilage damage and degeneration. The objective of this study was to evaluate the capability of MR T₁ρ to detect cartilage lesions as evaluated by arthroscopy in acutely ACL-injured knees and to compare with the Whole-Organ Magnetic Resonance Imaging Score (WORMS) using clinical standard MRI.

Method

Ten healthy controls (mean age 35) with no ACL injury or history of osteoarthritis (OA) and 10 patients with acute ACL injuries (mean age 39) were scanned at 3 Tesla (3 T). ACL patients underwent ACL reconstruction, where focal lesions were graded according to an Outerbridge grading system during arthroscopic evaluation. Normalized MR T₁ρ values (T₁ρ z-scores normalized to control values in matched regions) in full thickness, and superficial and deep layers of cartilage were compared between defined sub-compartments with and without focal lesions. Intraclass (ICC) correlation and the root mean square coefficient of variation (RMS-CV) were performed to evaluate the inter-observer reproducibility of T₁ρ quantification. Sub-compartments of cartilage were also evaluated using WORMS scoring and compared to their Outerbridge score respectively.

Results

The inter-observer ICC and the RMS-CV of the sub-compartment T₁ρ quantification were 0.961 and 3.9%, respectively. The average T₁ρ z-scores were significantly increased in sub-compartments with focal lesions compared to those without focal lesions and to the control cohort (p < 0.05).

Conclusion

Our results indicate that T₁ρ provided a better diagnostic capability than clinical standard MRI grading in detecting focal cartilage abnormalities after acute injuries. Quantitative MRI may have great potential in detecting cartilage abnormalities and degeneration non-invasively, which are occult with standard morphological MRI.     

MRI rotating frame relaxation measurements for articular cartilage assessment

In the present work we introduced two MRI rotating frame relaxation methods, namely adiabatic T_1ρ and Relaxation Along a Fictitious Field (RAFF), along with an inversion-prepared Magnetization Transfer (MT) protocol for assessment of articular cartilage. Given the inherent sensitivity of rotating frame relaxation methods to slow molecular motions that are relevant in cartilage, we hypothesized that adiabatic T_1ρ and RAFF would have higher sensitivity to articular cartilage degradation as compared to laboratory frame T₂ and MT. To test this hypothesis, a proteoglycan depletion model was used. Relaxation time measurements were performed at 0 and 48 h in 10 bovine patellar specimens, 5 of which were treated with trypsin and 5 untreated controls were stored under identical conditions in isotonic saline for 48 h. Relaxation times measured at 48 h were longer than those measured at 0 h in both groups. The changes in T₂ and MT relaxation times after 48 h were approximately 3 times larger in the trypsin treated specimens as compared to the untreated group, whereas increases of adiabatic T_1ρ and RAFF were 4 to 5 fold larger. Overall, these findings demonstrate a higher sensitivity of adiabatic T_1ρ and RAFF to the trypsin-induced changes in bovine patellar cartilage as compared to the commonly used T₂ and MT. Since adiabatic T_1ρ and RAFF are advantageous for human applications as compared to standard continuous-wave T_1ρ methods, adiabatic T_1ρ and RAFF are promising tools for assessing cartilage degradation in clinical settings.     

Blood oxygen level-dependent and perfusion magnetic resonance imaging: detecting differences in oxygen bioavailability and blood flow in transplanted kidneys

Functional magnetic resonance imaging (fMRI) is a powerful tool for examining kidney function, including organ blood flow and oxygen bioavailability. We have used contrast enhanced perfusion and blood oxygen level-dependent (BOLD) MRI to assess kidney transplants with normal function, acute tubular necrosis (ATN) and acute rejection. BOLD and MR-perfusion imaging were performed on 17 subjects with recently transplanted kidneys. There was a significant difference between medullary R2? values in the group with acute rejection (R2?=16.2/s) compared to allografts with ATN (R2?=19.8/s; P=.047) and normal-functioning allografts (R2?=24.3/s;P=.0003). There was a significant difference between medullary perfusion measurements in the group with acute rejection (124.4±41.1 ml/100 g per minute) compared to those in patients with ATN (246.9±123.5 ml/100 g per minute; P=.02) and normal-functioning allografts (220.8±95.8 ml/100 g per minute; P=.02). This study highlights the utility of combining perfusion and BOLD MRI to assess renal function. We have demonstrated a decrease in medullary R2? (decrease deoxyhemoglobin) on BOLD MRI and a decrease in medullary blood flow by MR perfusion imaging in those allografts with acute rejection, which indicates an increase in medullary oxygen bioavailability in allografts with rejection, despite a decrease in blood flow.     

Influence of the hepatobiliary contrast agent mangafodipir trisodium (Mn-DPDP) on the imaging properties of abdominal organs

To assess the influence of Mangafodipir Trisodium on the imaging properties of abdominal organs when using T₁-weighted gradient-echo (GE) and T₂-weighted turbo spin-echo (TSE) sequences, thirty patients with focal lesions in the liver were examined at a field strength of 1.5 T before and after intravenous administration of Mangafodipir Trisodium (dose: 5 μmol/kg of body weight).Administration of Mangafodipir Trisodium led to a significant increase in the signal intensity of the liver tissue (p < 0.001), the spleen (p < 0.01), the pancreas (p < 0.001), and the kidneys (p < 0.001) in the T₁-weighted GE sequence, while there was no relevant enhancement in fatty tissue and the musculature. In the T₂-weighted turbo spin-echo sequence, there was no relevant change in the signal following administration of a contrast agent. The contrast-to-noise ratio (C/N) between the lesions and the liver tissue increased significantly in the post-contrast T₁-weighted GE sequence (p < 0.001), while there was no change in the contrast-to-noise ratio in the post-contrast T₂-weighted turbo spin-echo sequence. The contrast-to-noise ratio of the plain T₂-weighted TSE sequence was significantly higher than that in the post-contrast T₁-weighted GE sequence (p < 0.001). Although Mangafodipir Trisodium was primarily developed as a hepatobiliary contrast agent for demonstration and differentiation of liver lesions, it also affects the signal levels in the pancreas, spleen, and kidneys in the T₁-weighted image. Awareness of this effect on the extrahepatic tissue makes it easier to interpret pathological findings in magnetic resonance imaging (MRI) of the abdomen.     

Neurofibrillary tangles and plaques are not accompanied by white matter pathology in aged triple transgenic-Alzheimer disease mice

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is the most common cause of dementia in aging populations. Although senile plaques and neurofibrillary tangles are well-established hallmarks of AD, changes in cerebral white matter correlate with cognitive decline and may increase the risk of the development of dementia. We used the triple transgenic (3xTg)-AD mouse model of AD, previously used to show that white matter changes precede plaque formation, to test the hypothesis that MRI detectable changes occur in the corpus callosum, external capsule and the fornix. T₂-weighted and diffusion tensor magnetic resonance imaging and histological stains were employed to assess white matter in older (11–17 months) 3xTg-AD mice and controls. We found no statistically significant changes in white matter between 3xTg-AD mice and controls, despite well-developed neurofibrillary tangles and beta amyloid immunoreactive plaques. Myelin staining was normal in affected mice. These data suggest that the 3xTg-AD mouse model does not develop MRI detectable white matter changes at the ages we examined.     

Regional variations in MR relaxation of hip joint cartilage in subjects with and without femoralacetabular impingement

The objective of this study was to analyze regional variations of magnetic resonance (MR) relaxation times (T_1ρ and T₂) in hip joint cartilage of healthy volunteers and subjects with femoral acetabular impingement (FAI). Morphological and quantitative images of the hip joints of 12 healthy volunteers and 9 FAI patients were obtained using a 3 T MR scanner. Both femoral and acetabular cartilage layers in each joint were semi-automatically segmented on sagittal 3D high-resolution spoiled gradient echo (SPGR) images. These segmented regions of interest (ROIs) were automatically divided radially into twelve equal sub-regions (30⁰ intervals) based on the fitted center of the femur head. The mean value of T_1ρ/T₂ was calculated in each sub-region after superimposing the divided cartilage contours on the MR relaxation (T_1ρ/T₂) maps to quantify the relaxation times. T_1ρ and T₂ relaxation times of the femoral cartilage were significantly higher in FAI subjects compared to healthy controls (39.9 ± 3.3 msec in FAI vs. 35.4 ± 2.3 msec in controls for T_1ρ (P = 0.0020); 33.9 ± 3.1 msec in FAI vs. 31.1 ± 1.7 msec in controls for T₂ (P = 0.0160)). Sub-regional analysis showed significantly different T_1ρ and T₂ relaxation times in the anterior-superior region (R9) of the hip joint cartilage between subjects with FAI and healthy subjects, suggesting possible regional differences in cartilage matrix composition between these two groups. Receiver operating characteristic (ROC) analysis showed that sub-regional analysis in femoral cartilage was more sensitive in discriminating FAI joint cartilage from that of healthy joints than global analysis of the whole region (T_1ρ: area under the curve (AUC) = 0.981, P = 0.0001 for R9 sub-region; AUC = 0.901, P = 0.002 for whole region; T₂: AUC = 0.976, P = 0.0005 for R9 sub-region; AUC = 0.808, P = 0.0124 for whole region). The results of this study demonstrated regional variations in hip cartilage composition using MR relaxation times (T_1ρ and T₂) and suggested that analysis based on local regions was more sensitive than global measures in subjects with and without FAI.     

Recovery of accurate T2 from historical 1.5 tesla proton density and T2-weighted images: Application to 7-year T2 changes in multiple sclerosis brain

ObjectiveTo determine accurate quantitative transverse relaxation times (T₂) using retrospective clinical images and apply it to examine 7-year changes in multiple sclerosis (MS) brain.MethodsA method for T₂ mapping from retrospective proton density (PD) and T₂-weighted fast spin echo images was recently introduced, but requires measurement of flip angles. We examined whether 1.5 T flip angle variation in brain can be predicted, thus enabling T₂ analysis of historical PD and T₂-weighted images without a concurrent flip angle map. After method validation in healthy volunteers, retrospective longitudinal T₂ analysis was performed in 14 MS subjects over seven years. Changes in patient T₂ values were compared with brain atrophy, T₂ lesion load and disability score in MS.ResultsSimilar flip angle maps across volunteers enabled retrospective T₂ from PD and T₂-weighted images even when different refocusing angles were used. Over seven years, significant T₂ changes of 2–4% were observed when using T₂ modelling and the 7-year effect size for globus pallidus T₂ was 0.56, which was more significant than brain atrophy. No significant T₂ results were found when using exponential fit, which cannot account for refocusing angle variation. Moreover, change is T₂ in globus pallidus and internal capsule correlated with MS disability score over time when using T₂ modelling.ConclusionsAccurate quantitative T₂ can be extracted from standard clinical 1.5 T MRI exams that include PD and T₂-weighted imaging even when no flip angle map is available. This method was applied retrospectively to examine seven year changes in MS.     

Large reversible magnetocaloric effect in spinel MnV2O4 with minimal Al substitution

Magnetocaloric effect of MnV_1.95Al_0.05O₄ was studied by the magnetization and heat capacity measurements. MnV_1.95Al_0.05O₄ is a cubic spinel structure with ferromagnetism of second order in nature and performs reversible magnetic entropy around the magnetic transition temperature. The large magnetic entropy changes −ΔS_M∼5.2 and 8.2 J/kg K and the adiabatic temperature changes ΔT_ad∼1.5 and 2.6 K are revealed for the magnetic field changes of 2 and 4 T near the Curie temperature (T_C) of 59.6 K, respectively. The relative cooling power (RCP) are about 82.2 and 177.2 J/kg K for magnetic field changes 2 and 4 T, respectively. Compared with the parent compound, although the −ΔS_M and ΔT_ad become smaller, the refrigeration working temperature span and the RCP have been improved.     

Effect of substrate temperature on structure and electrical resistivity of laser-ablated IrO2 thin films

IrO₂ thin films were prepared on Si(1 0 0) substrates by laser ablation. The effect of substrate temperature (T_sub) on the structure (crystal orientation and surface morphology) and property (electrical resistivity) of the laser-ablated IrO₂ thin films was investigated. Well crystallized and single-phase IrO₂ thin films were obtained at T_sub = 573-773 K in an oxygen partial pressure of 20 Pa. The preferred orientation of the laser-ablated IrO₂ thin films changed from (2 0 0) to (1 1 0) and (1 0 1) depending on T_sub. With the increasing of T_sub, both the surface roughness and crystallite size increased. The room-temperature electrical resistivity of IrO₂ thin films decreased with increasing T_sub, showing a low value of (42 ± 6) × 10⁻⁸ Ω m at T_sub = 773 K.     

Iron isotope effect on Tc in optimally-doped (Ba,K)Fe2As2 (Tc = 38 K) and SmFeAsO1−y (Tc = 54 K) superconductors

We report the iron isotope effect on a transition temperature (T_c) in an optimally-doped (Ba,K)Fe₂As₂ (T_c = 38 K) and SmFeAsO_1−y (T_c = 54 K) superconductors. In order to obtain the reliable isotope shift in T_c, twin samples with different iron isotope mass are synthesized in the same conditions (simultaneously) under high-pressure. We have found that (Ba,K)Fe₂As₂ shows an inverse iron isotope effect α_Fe = −0.18 ± 0.03 while SmFeAsO_1−y shows a small iron isotope effect α_Fe = −0.02 ± 0.01, where the isotope exponent α is defined by T_c ∼ M^−α (M is the isotopic mass). The results show that α_Fe changes in the iron-based superconductors depending on the system. The distinct iron isotope effects imply the exotic coupling mechanism in the iron-based superconductors.     

Semiquantitative perfusion combined with diffusion-weighted MR imaging in pre-operative evaluation of endometrial carcinoma: Results in a group of 57 patients

Purpose

To evaluate the semiquantitative DCE and quantitative DWI parameters in endometrial cancer, in order to assess the presence of neoplastic tissue and normal myometrium and to ascertain a potential relationship with tumor grade.

Methods and materials

A total of 57 patients with biopsy-proven endometrial adenocarcinoma who underwent MR imaging examination for staging purposes were retrospectively evaluated. Imaging protocol included multiplanar T₁- and T₂-weighted TSE, DCE T₁-weighted (THRIVE; 0, 30, 90 and 120 seconds after intravenous injection of gadolinium) and DWIBS sequences (b values = 0 and 1000 mm²/s). Color perfusion and ADC maps were automatically generated on dedicated software. Relative enhancement (RE, %), maximum enhancement (ME, %), maximum relative enhancement (MRE, %), time to peak (TTP, s) and mean apparent diffusion coefficient (ADC) were calculated by manually drawing a region of interest (ROI) both on the neoplastic tissue and the normal myometrium. Histopathology was used as reference standard.

Results

Histopathological analysis confirmed the presence of endometrial carcinoma in all patients. Neoplastic tissue demonstrated significantly lower (P < 0.001) values of RE (%) 63.92 ± 35.68; ME (%) 864.91 ± 429.54 and MRE (%) 75.97 ± 38.26 as compared to normal myometrium (RE (%) 151.43 ± 55.99; ME (%) 1800.73 ± 721.32; MRE (%) 158.28 ± 54.05). TTP was significantly higher (P < 0.05) in tumor lesion (385.51 ± 1630.27 vs 195.44 ± 78.69). Mean ADC value of neoplastic tissue (775.09 ± ?220.73 × 10^− 3 mm²/s) was significantly lower (P < 0.05) than in myometrium (1602.37 ± 378.54 × 10^− 3 mm²/s). The analysis of perfusion and diffusion parameters classified according to tumor grades, showed a statistically significant difference only for RE (P = 0.043) and ME (P = 0.007).

Conclusions

Perfusion parameters and mean ADC differ significantly between endometrial cancer and normal myometrium, potentially reflecting the different microscopical features of cellularity and vascularity; however a significant relationship with tumor grade was not found in our series.     

MR imaging of non-cancerous hepatic lesions in Long-Evans Cinnamon rats

We measured MR images of the liver of Long-Evans Cinnamon (LEC) rats with pathologic correlation and assessed the effectiveness of MR imaging (MRI) for diagnosis of noncancerous hepatic lesions. T₁- and T₂-weighted images of their livers were obtained, and the dynamic and delayed studies after intravenous gadolinium injection were also performed. Cholangiofibrosis showed low signal intensity on T₁-weighted images and high signal intensity on T₂-weighted images. The T₂ relaxation time of cholangiofibrosis was significantly prolonged (p < .01), and the signal intensity ratio of this lesion to muscle on T₁-weighted images was significantly lower than that of normal liver parenchyma to muscle (p < .01). The lesion was enhanced immediately after gadolinium injection and the enhancement was prolonged. Among three cases of peliosis hepatis identified, one showed heterogeneous intensities on both T₁- and T₂-weighted images and the other two showed similar intensity pattern to cholangiofibrosis. The characteristic MR appearance of cholangiofibrosis may be useful to distinguish it from hepatocellular carcinoma (HCC).