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Background: Gadolinium-based contrast agents (GBCA) are commonly used in MRI. GBCA have been linked to signal changes in dentate nucleus and globus pallidus. Purpose: To assess the degree of gadolinium accumulation in brain structures among patients with GBCA administrations. Materials and methods: Retrospective study included 224 patients: 197 patients who underwent more than two MRI with linear-type GBCA and 27 patients from control group who underwent at least two MRI without GBCA. Results: Statistical analysis of the main group revealed positive correlation between difference in signal intensity of GP/thalamus ratio to the number of previous MRI with GBCA (r=0.145, p=0.042), with a time interval between first and last MRI (r=0,221, p=0,002), as well as to patients age (r=0.145, p=0.042). For difference in ND/ pons ratio positive correlation was found only with the number of previous studies with GBCA (r=0.172, p=0.016). Statistical analysis of patients who received GBCA of the same type (gadodiamide or gadopentetic acid) revealed the following correlations: in patients who were administered gadodiamide, a positive correlation was found between ND/pons ratio and the number of previous studies with GBCA (r=0,280, p

OBJECTIVES Reports on gadolinium (Gd) retention in soft tissues after administration of Gd-based contrast agents (GBCAs) raise concerns about Gd-induced changes in the biophysical properties of cells and tissues. Here, we investigate if clinical GBCAs of both classes of linear and macrocyclic structure cause changes in the mechanical properties of leukocytes in human blood samples. MATERIAL AND METHODS Real-time deformability cytometry was applied to human blood samples from 6 donors. The samples were treated with 1 mM gadoteric acid (Dotarem), gadopentetic acid (Magnevist), gadobutrol (Gadovist), or Gd trichloride at 37°C for 1 hour to mimic clinical doses of GBCAs and exposure times. Leukocyte subtypes-lymphocytes, monocytes, and neutrophils-were identified based on their size and brightness and analyzed for deformability, which is inversely correlated with cellular stiffness. RESULTS We observed significant stiffening (3%-13%, P < 0.01) of all investigated leukocyte subtypes, which was most pronounced for lymphocytes, followed by neutrophils and monocytes, and the effects were independent of the charge and steric structure of the GBCA applied. In contrast, no changes in cell size and brightness were observed, suggesting that deformability and cell stiffness measured by real-time deformability cytometry are sensitive to changes in the physical phenotypes of leukocytes after GBCA exposure. CONCLUSIONS Real-time deformability cytometry might provide a quantitative blood marker for critical changes in the physical properties of blood cells in patients undergoing GBCA-enhanced magnetic resonance imaging.

Purpose Through analysis of T1-weighted (T1w) images this study investigated gadolinium (Gd) deposition in the brain after administration of a linear (gadopentetic acid) and a cyclic (gadoteric acid) gadolinium-based contrast agent (GBCA) in patients with multiple sclerosis (MS), a disorder frequently requiring magnetic resonance imaging (MRI) scans over years. Methods A total of 3233 T1w images (unenhanced with respect to the same scanning session) of 881 MS patients were retrospectively analyzed. After spatial normalization and intensity scaling using a sphere within the pons, differences of all pairs of subsequent scans were calculated and attributed to either linear (n = 2718) or cyclic (n = 385) or no GBCA (n = 130) according to the first scan. Regional analyses were performed, focusing on the dentate nucleus, and whole brain analyses. By 1‑sample t‑tests, signal intensity increases within conditions were searched for; conditions were compared by 2‑sample t‑tests. Furthermore, recent hypotheses on the reversibility of GBCA deposition were tested. Results In the dentate nucleus, a significant increase was observed only after administration of linear GBCA even after a single GBCA administration. This increase differed significantly (p Conclusion The data point towards Gd deposition in the brain after administration of linear GBCA even after a single administration.

Objectives To assess the applicability of a novel hybrid dextran-gadolinium nanoparticles (NPs) as high-relaxivity T1 magnetic resonance imaging (MRI) contrast agent for mapping the sentinel lymph node (SLN). Methods Dextran-bis-acrylamide-polyacrylic acid (Dex-MBA-PAA) NPs were synthesized through a self-assembly assisted approach and complexed with multiple chelated gadolinium (Gd) (III) ions. After their characterization was validated, they were used to mapping SLNs by MRI in Wistar rats, and their biosafety was evaluated. Results Dextran-MBA-polyacrylic acid-Gd NPs have suitable particle size and much higher longitudinal relaxivity (r1) than that of commonly used clinical MRI contrast agents (eg, gadopentetic acid dimeglumine salt injection). The in vivo T1-weighted MRI results revealed their effectiveness at mapping SLNs. And their biological safety was also verified. Conclusions Dextran-MBA-polyacrylic acid-Gd NPs were synthesized and validated by in vitro and in vivo experiments for their ability to visualize SLNs by MRI with accurate positioning and excellent biosafety, and they have great potential for clinical SLN mapping.

Purpose Phosphorous MR spectroscopy (31P‐MRS) forms a powerful, non‐invasive research tool to quantify the energetics of the heart in diverse patient populations. 31P‐MRS is frequently applied alongside other radiological examinations, many of which use various contrast agents that shorten relaxation times of water in conventional proton MR, for a better characterisation of cardiac function, or following prior computed tomography (CT). It is, however, unknown whether these agents confound 31P‐MRS signals, for example, 2,3‐diphosphoglycerate (2,3‐DPG). Methods In this work, we quantitatively assess the impact of non‐ionic, low osmolar iodinated CT contrast agent (iopamidol/Niopam), gadolinium chelates (linear gadopentetic acid dimeglumine/Magnevist and macrocyclic gadoterate meglumine/Dotarem) and superparamagnetic iron oxide nanoparticles (ferumoxytol/Feraheme) on the nuclear T1 and T2 of 31P metabolites (ie, 2,3‐DPG), and 1H in water in live human blood and saline phantoms at 11.7 T. Results Addition of all contrast agents led to significant shortening of all relaxation times in both 1H and 31P saline phantoms. On the contrary, the T1 relaxation time of 2,3‐DPG in blood was significantly shortened only by Magnevist (P = .03). Similarly, the only contrast agent that influenced the T2 relaxation times of 2,3‐DPG in blood samples was ferumoxytol (P = .02). Conclusion Our results show that, unlike conventional proton MR, phosphorus MRS is unconfounded in patients who have had prior CT with contrast, not all gadolinium‐based contrast agents influence 31P‐MRS data in vivo, and that ferumoxytol is a promising contrast agent for the reduction in 31P‐MRS blood‐pool signal.

The goal of this work was to develop a shape memory polymer (SMP) foam with visibility under both X-ray and magnetic resonance imaging (MRI) modalities. A porous polymeric material with these properties is desirable in medical device development for applications requiring thermoresponsive tissue scaffolds with clinical imaging capabilities. Dual modality visibility was achieved by chemically incorporating monomers with X-ray visible iodine-motifs and MRI visible monomers with gadolinium content. Physical and thermomechanical characterization showed the effect of increased gadopentetic acid (GPA) on shape memory behavior. Multiple compositions showed brightening effects in pilot, T1-weighted MR imaging. There was a correlation between the polymeric density and X-ray visibility on expanded and compressed SMP foams. Additionally, extractions and indirect cytocompatibility studies were performed to address toxicity concerns of gadolinium-based contrast agents (GBCAs). This material platform has the potential to be used in a variety of medical devices.

Hypothesis Furosemide alters the permeability of the intrastrial fluid-blood barrier. Background The cochlear sensory cells are protected by the blood-perilymph and intrastrial fluid-blood barriers, which hinder substances, including gadolinium-based contrast agents (GdCAs), to enter the endolymphatic space. High-dose furosemide causes transient shift of hearing thresholds and morphological changes in stria vascularis. Furosemide is also known to enhance drug-induced ototoxicity. Methods Furosemide (400 mg/kg b.w.) was injected i.v. in Balb/C mice (n = 20). Twenty minutes later, the GdCA gadobutrol, gadopentetic acid, or gadoteric acid was injected i.v. The distribution of GdCA to the perilymphatic and endolymphatic spaces was studied with MRI (9.4 T) for 250 minutes. Results The perilymphatic and endolymphatic spaces were signal-enhanced in all animals. Gadopentetic acid and gadoteric acid yielded similar signal enhancement in all three scalae, while gadobutrol yielded significantly higher enhancement in scala tympani than scala media (p = 0.043) and scala vestibuli (p = 0.043). The signal enhancement reached a plateau but did not decrease during the time of observation. Conclusion Treatment with a high dose of furosemide before injection of a GdCA resulted in enhancement of the MRI signal in the endolymphatic space as well as the perilymphatic space, which supports our hypothesis that furosemide alters the permeability of the intrastrial fluid-blood barrier.

Combination therapy based on nanomedicine has gained momentum in oncology in recent years, offering superior safety and efficacy over monotherapies. It is critical to design theranostics that are composed of imaging and therapeutic agents already approved. Herein, gadolinium (Gd)-rose bengal coordination polymer nanodots (GRDs) are reported. The GRDs exhibit a unique absorption property and 7.7-fold luminescence enhancement, as well as a 1.9-fold increase in singlet oxygen generation efficiency over free rose bengal. Meanwhile, GRDs exhibit a twofold increase in r1 relaxivity over gadopentetic acid (Gd-DTPA) and have better X-ray absorption ability than rose bengal alone. These excellent properties of the GRDs are verified both in vitro and in vivo. The combination of photodynamic therapy (PDT) and radiation therapy (RT) more significantly inhibits tumor growth than monotherapies (i.e., PDT or RT). This work offers a new route to designing and synthesizing Gd-based nanotheranostics for image-guided cancer therapy.

Purpose Tο fabricate a tissue-mimicking phantom simulating the MR relaxation times of neonatal gray and white matter at 1.5 T, for the optimization of clinical Τ1 weighted (T1w) and T2 weighted (T2w) sequences. Methods Numerous agarose gel solutions, doped with paramagnetic Gadopentetic acid (Gd-DTPA) ions, underwent quantitative relaxometry with a Turbo-Inversion-Recovery Spin-Echo (TIRSE) sequence and a Car-Purcell-Meiboom-Gill (CPMG) sequence for T1 and T2 measurements, respectively. Twenty samples which simulated the spectrum of relaxation times of neonatal brain parenchyma were selected. Reproducibility was tested by refabrication and relaxometry of the relevant samples while stability was tested by six sets of quantitative relaxometry scans during a 12-month period. Results “Neonatal gray matter equivalent”(0.6%w/v agarose-0.10 mM Gd-DTPA), accurately mimicked relaxation times of neonatal gray matter: T1 = (1134 ± 7)ms, T2 = (200 ± 7)ms. “Neonatal white matter equivalent”(0.3%w/v agarose-0.03 mM Gd-DTPA), accurately mimicked relaxation times of neonatal white matter: T1 = (1654 ± 9)ms, T2 = (376 ± 4)ms. Coefficient of variation of T1 and T2 relaxation times measurements remained less than 5% during 12 months. Sequences were modified according to maximum relative contrast (RC) between neonatal gray and white matter equivalents. Optimized T2wTSE and T1wTSE parameters were TR/TE = 9500 ms/280 ms and TR/TE = 1200 ms/10 ms, respectively for a MAGNETOM Vision/Sonata Hybrid 1.5 T system. Quantitative relaxometry at different 1.5 T MR systems resulted in inter-system T1, T2 measurement deviations of 12% and 3%, respectively. Conclusion A precise, stable and reproducible phantom for the neonatal brain was fabricated. Subsequent optimization of clinical T1w and T2w sequences based on maximum RC between neonatal gray and white matter equivalents was scientifically supported with robust relaxometry. The procedure was applicable in different 1.5 T systems. Highlight TR & TE optimization of neonatal brain at 1.5 T was based on relaxometry of a stable, reproducible phantom.

Multifunctional nanoagents, in particular those that combine diverse diagnostic and therapeutic functions, have attracted great enthusiasm in oncotherapy. In this work, a triangular gold nanoprism decorated with gadopentetic acid (Gd–DTPA) (TGP–PEG–Gd) was constructed for use in cancer theranostics. TGP–PEG–Gd exhibits uniform morphology, excellent monodispersity and near infrared absorbance properties. The magnetic properties of gadolinium, together with the X-ray attenuation of gold, enable TGP–PEG–Gd to be employed for T1-weighted MR/CT dual-modality imaging. The longitudinal relaxivity (r1) of TGP–PEG–Gd was calculated to be 23.1 mM−1 s−1, and its X-ray absorption coefficient was 959.3 HU L g−1. In addition, TGP–PEG–Gd possesses effective photothermal conversion ability, which was utilized for successful photothermal therapy. Moreover, the excellent biocompatibility of TGP–PEG–Gd was proved both in vitro and in vivo. Biocompatible TGP–PEG–Gd may hold promise for the photothermal therapy of cancers guided by MR/CT dual-modality imaging.

Purpose: T1-Cube (GE HealthCare) is a relatively new 3-dimensional (3D) fast spin-echo (FSE)-based magnetic resonance (MR) imaging sequence that uses a variable flip angle to acquire gap-free volume scans. We compared the gadolinium enhancement characteristics of a heterogeneous population of brain tumors imaged by T1-Cube and then 3D fast spoiled gradient recall acquisition in steady state (3D FSPGR) 3-tesla MR imaging to identify the superior modality for specific diagnostic purposes. Methods: We examined 61 lesions from 32 patients using the 2 sequences after administration of gadopentetic acid (Gd-DTPA; 0.1 mmol/kg). Two neuroradiologists independently measured each lesion twice using a region-of-interest (ROI) method. We measured the contrast-to-noise ratio (CNR), the difference in signal intensity (SI) between the tumor and normal white matter relative to the standard deviation (SD) of the SI within the lesion, for both post-contrast 3D FSPGR and post-contrast T1-Cube images of the same tumor and compared modality-specific CNRs for all tumors and in subgroups defined by tumor size, enhancement ratio, and histopathology. Results: The mean CNR was significantly higher on T1-Cube images than 3D FSPGR images for the total tumor population (1.85 ± 0.97 versus 1.12 ± 1.05, P < 0.01) and the histologic types, i.e., metastasis (P < 0.01) and lymphoma (P < 0.05). The difference in CNR was even larger for smaller tumors in the metastatic group (4.95 to 23.5 mm2) (P < 0.01). In contrast, mean CNRs did not differ between modalities for high grade glioma and meningioma. Conclusions: Gadolinium enhancement of brain tumors was generally higher when imaged by T1-Cube than 3D FSPGR, and T1-Cube with Gd enhancement may be superior to 3D FSPGR for detecting smaller metastatic tumors.

Currently, the development of polysaccharide, especially chitosan (CS), based drug delivery system to afford magnetic resonance imaging (MRI) guided theranostic cancer therapy remains largely unexplored. Herein, we successfully developed a CS derived polymer (Gd-CS-OA) through chemical conjugation of CS, octadecanoic acid (OA) and gadopentetic acid (GA). After self-assemble into glycolipid nanoparticles to loaded chlorin e6 (Ce6), the resulted Gd-CS-OA/Ce6 was able to realize MRI guided photodynamic therapy (PDT) of cancer. Our results revealed that Gd-CS-OA was able to increase the MRI sensitivity as compared to Gd-DTPA with decent residence time and preferable excretion behavior in vivo. Moreover, the Gd-CS-OA/Ce6 showed negligible hemolysis, satisfactory ROS generation and stability in physiological environments with preferable cellular uptake and enhanced in vitro cytotoxicity (through elevated ROS generation) on 4T1 cells. Most importantly, Gd-CS-OA/Ce6 demonstrated promising in vivo tumor targetability (enhanced penetration and retention effect) and powerful MRI guided tumor ablation through PDT on in situ 4T1 tumor model.

The early diagnosis of prostate cancer (PCa) is particularly important for reducing its high mortality rate. With the development of molecular magnetic resonance imaging (MRI), early diagnosis via non-invasive imaging has become possible. In this study, gadopentetic acid (GA)-doped silica (Gd@SiO2) was first synthesized by a reverse microemulsion method, and amino and carboxyl groups were then successively introduced onto the surface of this Gd@SiO2. After these steps, a monoclonal antibody (YPSMA-1) to prostate-specific membrane antigen (PSMA) was conjugated with carboxyl-modified Gd@SiO2 (Gd@SiO2-COOH) nanoparticles (NPs) by the carbodiimide method. Gd@SiO2-Ab NPs were thus obtained as specific MR contrast agents for PCa-targeted imaging. Transmission electron microscopy showed that the Gd@SiO2-Ab NPs exhibited a dispersed spherical morphology with a relatively uniform size distribution. The Gd@SiO2-Ab NPs showed high stability and high the longitudinal relaxation rate (r1). Cell-targeting experiments in vitro demonstrated the high potential of the synthesized NPs to target PSMA receptor-positive PCa cells. In vitro cytotoxicity assays showed that the Gd@SiO2-Ab NPs exhibited good biological safety. These results suggest that the synthesized Gd@SiO2-Ab NPs have great potential as specific MR contrast agents for PSMA receptor-positive PCa cells.

WOS: 000405006500003 PubMed ID: 28651625 Background: Magnetic resonance arthrography, a procedure through which contrast agents containing gadolinium and/or iopromide are administered intra-articularly, has become a useful tool in musculoskeletal diagnosis. Nevertheless, despite being considered safe for systemic use, certain tissue toxicities have been identified for both drugs. In this study, the effects of short-term exposure of human primary chondrocyte cell cultures to gadolinium and/or iopromide contrast agents were examined by assaying for stage-specific embryonic antigen-1 (SSEA-1) protein expression (a chondrogenic differentiation marker), cell viability, toxicity, and proliferation. Methods: Human articular chondrocytes were grown in monolayer culture and were exposed to iopromide and/or gadolinium diethylenetriamine-pentaacetate (Gd-DPT) for 2 and 6 h. Cell cultures with no drug exposure were used as the control group. Cell differentiation status was assessed according to SSEA-1 protein expression. Contrast agent effects on cell viability and proliferation were analyzed using MTT analysis. Further, changes in cell morphology in relation to the control group were evaluated using inverted light microscopy, environmental scanning electron microscopy (ESEM), and 3-tesla magnetic resonance imaging. The obtained data were statistically compared. Results: When compared with the control group, both SSEA-1 protein expression and cell proliferation were lowest in the Gd-DPT group (P = 0.000). There was a statistically significant correlation between SSEA-1 expression and MTT results (rho = 0.351; P = 0.003). Conclusions: Nevertheless, the data obtained from in vitro experiments may not directly correspond to clinical applications. However, the mere fact that a drug used solely for diagnostic purposes may repress chondrocyte cell proliferation should be carefully considered by clinicians.

Strategic design of gadofullerene derivatives is critical to integrate multifunctionality into one entity. Herein, an easy method was developed to fabricate a new type of magnetic resonance imaging/fluorescent integrative molecular imaging probe based on Gd@C82. The functionalized gadofulleride Gd@C82O∼14(OH)∼14(NH2)∼6 not only exhibits an order of magnitude larger relaxivity (47.0 ± 0.8 mM−1 s−1 at 0.5 T) than commercially used gadopentetic acid (4.5 ± 0.1 mM−1 s−1) under the same condition and multi-wavelength emission features derived from the multi-wavelength excitation for dual-modality diagnosis, but also highly efficient scavenging capability toward hydroxyl radicals.

Contrast-enhanced magnetic resonance imaging has become a routine diagnostic procedure. One of the most common contrast agents used for MRI is gadopentetic acid (Gd-DTPA, marketed as Magnevist). In this work, we studied the relaxivity of Gd-DTPA covalently bonded to β-cyclodextrin and compared enhancement properties of this compound and Magnevist. Our work demonstrated high relaxivity of Gd-DTPA complex containing 80 % of Gd-DTPA-modified β-cyclodextrin mono-derivative, 10 % of Gd-DTPA-modified β-cyclodextrin di-derivative and 10 % of Gd-DTPA-modified β-cyclodextrin tri-derivative. Gd-DTPA residues were linked to β-cyclodextrin by an ester bond, in which a COOH group belongs to DTPA and OH is a β-cyclodextrin surface hydroxyl group. It was proved experimentally that the studied compound is not toxic in concentrations necessary for diagnostic procedures. Compared to Magnevist, it can provide similar enhancement when used in just half of the equivalent amount., В настоящее время широко используют диагностическую процедуру на основе магнитно-резонансной томографии с применением контрастных средств, из которых наиболее часто применяют гадопентетовую кислоту (Gd-ДТПА, лекарственная форма — препарат «Магневист»). Данная работа посвящена изучению релаксирующей способности Gd-ДТПА, ковалентно соединенного с β-циклодекстрином, и сравнительной оценке визуализирующей способности изучаемого соединения и «Магневиста». Показано, что высокой релаксирующей способностью обладает комплекс Gd-ДТПА, состоящий из 80 % монопроизводного Gd-ДТПА-β-циклодекстрина и содержащий по 10 % дии трипроизводного Gd-ДТПА циклического углевода. Остатки Gd-ДТПА соединены с β-циклодекстрином сложноэфирной связью, где –СООН относится к ДТПА, а ОН — поверхностные гидроксилы β-циклодекстрина. Экспериментально доказано, что изучаемое соединение не обладает токсичностью в диагностических концетрациях. Визуализирующая способность аналогичная «Магневисту» может быть достигнута введением меньшего, до 50 %, количества препарата.

Controlled self-assembly of organic/inorganic magnetic hybrid materials have important applications in magnetic resonance imaging (MRI). In this study, a widely used polycation polyethylenimine was conjugated with gadopentetic acid (Gd-DTPA) as a gadolinium bearing polyelectrolyte (Gd-DTPA-PEI). Next, multilayers of Gd-DTPA-PEI were coated on silica nanoparticles through layer-by-layer (LbL) self-assembly with polyanions as monitored by dynamic light scattering, zeta-potential, and scanning electron microscopy. The thickness of the multilayer film was estimated from quartz crystal microbalance based on counting frequency change of each adsorbed layer. The magnetic relaxation of SiO2/(Gd-DTPA-PEl/polyanion), core-shell nanocomposite was tested at 1.5 T magnetic field in a clinical MRI scanner, and a 3-fold increase in T1 relaxivity to 15.1 Gd mM(-1)s(-1) was noticed comparing to Gd-DTPA small molecules. Dextran sulfate was coated as the outermost layer on the nanocomposite for better biocompatibility as verified by in vitro cytotoxicity studies. This formulation provides good signal intensity enhancement of mouse liver in vivo with only 1/25 dose of clinical standard at 30 and 60 minutes after intravenous injection. This sensitive imaging probe with unique core-shell structures may find broad applications in cellular and molecular imaging.

Purpose Primary pulmonary artery sarcomas are very rare tumors. Their diagnosis is difficult due to their unspecific symptoms. Still, an early preoperative diagnosis is the only possibility for a potential therapy. Patients and methods 4 pre- and 5 postoperative CT- and three pre- and one postoperative MRT-examination(s) have been evaluated with respect to surgical and histological findings. Results The presence of a convex intraluminal bulging mass spreading mostly from the pulmonary trunc continuously into the peripheral pulmonary artery branches the filling and dilatation of the vessels, the tumor's inhomogeneity indicating hemorrhages and necrosis and the appearance of intrapulmonary nodules are found in both CT and MRI. Recurrent pulmonary artery sarcoma features an extravascular growth and is similar to lung cancer affecting the vessels. It shows contrast enhancement both in CT and MRI while the primary tumor shows a distinct contrast enhancement only of Gadopentetate dimeglumine but none or little enhancement in CT. Conclusion The criteria presented in knowledge of CT and MRI serve to increase the probability for a correct preoperative diagnosis and thus allow adequate surgical planning.

PURPOSE Pulsed arterial spin labeling (PASL) is a magnetic resonance (MR) method for measuring cerebral blood flow. Although several validation studies for PASL in animals and humans have been reported, no reports have detailed the fundamental study of PASL using a flow phantom. We compared the true and theoretical flow rates in a flow phantom to confirm the analytical validity of quantitative perfusion imaging with Q2TIPS sequence. METHODS We built a flow phantom consisting of a 40-mm diameter plastic syringe filled with plastic beads and small plastic tubes 4 mm in diameter. Gd-DTPA-doped 8L water solution (0.1 mM) was circulated between the syringe and a tank through a plastic tube by a constant flow pump while the flow rate was adjusted between 0 and 2.61 cm/s. Q2TIPS sequence parameters were TI(1)=50 ms and TI(2)=1400 ms. Five imaging slices of 50 subtraction images were acquired sequentially in a distal-to-proximal direction using a single-shot echo planar imaging (EPI) technique. The theoretical flow rate calculated based upon the previously reported kinetic model for Q2TIPS was compared with the true flow rate. RESULTS A good linear relationship was observed between the theoretical, F', and true flow rates, F, in a flow rate range of 1.43 to 1.95 cm/s (F'=1.024*F-1.915, R(2)=0.902). The ratio of theoretical to true flow rate was 92 (+/-) 4%. CONCLUSION Flow rate was quantified with reasonable accuracy when the entire amount of labeled bolus within the phantom could be recovered. Our experiment confirmed the analytical validity of Q2TIPS and suggested that blood flow measurement may be feasible using the Q2TIPS pulse sequence and kinetic model of the PASL equation.

The Side Effects of Drugs: Annual is a series of volumes in which the adverse effects of drugs and adverse reactions to them are surveyed. The series supplements the contents of Meyler's Side Effects of Drugs: the International Encyclopedia of Adverse Drug Reactions and Interactions. This review of the 2014 publications on radiological contrast agents and radiopharmaceuticals covers adverse events reported in case studies surrounding iodinated water-soluble contrast media, gadolinium salts, superparamagnetic iron oxide (SPIO) MRI contrast agents, and ultrasound contrast agents. It includes a special review on iodinated radiocontrast-induced nephropathy.

Brain metastases are an important clinical problem. Few animal models exist for melanoma brain metastases; many of which are not clinically relevant. Longitudinal MRI was implemented to examine the development of tumors in a clinically relevant mouse model of melanoma brain metastases. Fifty thousand human metastatic melanoma (A2058) cells were injected intracardially into nude mice. Three Tesla MRI was performed using a custom-built gradient insert coil and a mouse solenoid head coil. Imaging was performed on consecutive days at four time points. Tumor burden and volumes of metastases were measured from balanced steady-state free precession image data. Metastases with a disrupted blood-tumor barrier were identified from T1-weighted spin echo images acquired after administration of gadopentetic acid (Gd-DTPA). Metastases permeable to Gd-DTPA showed signal enhancement. The number of enhancing metastases was determined by comparing balanced steady-state free precession images with T1-weighted spin echo images. After the final imaging session, ex-vivo permeability and histological analyses were carried out. Imaging showed that both enhancing and nonenhancing brain metastases coexist in the brain, and that most metastases switched from the nonenhancing to the enhancing phenotype. Small numbers of brain metastases were enhancing when first detected by MRI and remained enhancing, whereas other metastases remained nonenhancing to Gd-DTPA throughout the experiment. No clear relationship existed between the permeability of brain metastases and size, brain location and age. Longitudinal in-vivo MRI is key to studying the complex and dynamic processes of metastasis and changes in the blood-tumor barrier permeability, which may lead to a better understanding of the variable responses of brain metastases to treatments.

To compare the kinetic physiologic properties of a clinical contrast agent, gadopentetate dimeglumine, with those of ultrasmall superparamagnetic iron oxide (USPIO) particles for dynamic contrast material-enhanced magnetic resonance (MR) imaging of tumor angiogenesis in human colon carcinoma in mice with a clinical MR imaging unit.Thirty-two mice with human colon carcinoma were injected with either gadopentetate dimeglumine (n = 16) or USPIO (n = 16) for dynamic contrast-enhanced MR imaging and pre- and postcontrast T2 and T2* measurements. Dynamic contrast-enhanced MR imaging measurements were analyzed by using a two-compartment model to calculate the endothelial transfer coefficient surface area product (KPS) for the tumor microvasculature, the reflux coefficient (k), and the fractional plasma volume (fPV). KPS, k, and fPV maps were compared with histologic microvessel density (MVD) and used to observe differences between core and rim regions of tumor.Results in 30 mice (15 in the gadopentetate dimeglumine group and 15 in the USPIO group) could be used. KPS values measured with both agents correlated well with MVD in hot spots (gadopentetate dimeglumine: r = 0.6, P =.02; USPIO: r = 0.6, P =.01). No significant difference (P =.4) in correlation was found between the two agents. Both USPIO and gadopentetate dimeglumine demonstrated higher MVD and KPS values in tumor rim than in tumor core (P.01). Tumor k values correlated poorly with whole-tumor MVD for both gadopentetate dimeglumine (r = 0.3, P =.4) and USPIO (r = 0.2, P =.6), while fPV values correlated well with whole-tumor MVD for USPIO (r = 0.6, P =.02) but not gadopentetate dimeglumine (r = -0.01, P =.98). T2 and T2* measurements showed small differences between areas of high and low angiogenic activity with both agents.The kinetic physiologic properties of gadopentetate dimeglumine are as good as those of USPIO for dynamic contrast-enhanced MR imaging for calculating KPS as a measurement of angiogenesis in human colon carcinoma. Further studies with patients may reveal whether gadopentetate dimeglumine might be used for this purpose in clinical practice.

To compare the magnetic resonance (MR) imaging enhancement patterns of a blood pool contrast agent, SH L 643A, with those of gadopentetate dimeglumine in postoperative scars and VX2 carcinomas in rabbits and to compare these enhancement patterns with microvessel density in pathologic specimens.Eighteen rabbits with experimentally induced postoperative scars (n = 12) or VX2 carcinoma (n = 6) in the thighs underwent sequential MR imaging first with gadopentetate dimeglumine and then, 24 hours later, with SH L 643A. The enhancement ratios (ie, the ratios of postcontrast to precontrast signal intensity) and the microvessel densities of postoperative scars and VX2 carcinomas were assessed. Differences were tested for by using the Mann-Whitney U and Wilcoxon signed rank tests.In postoperative scars, enhancement ratios were consistently lower with injection of SH L 643A than with injection of gadopentetate dimeglumine for up to 30 minutes (P.05). In postoperative scars, mean peak enhancement ratios were 1.29 +/- 0.15 (SD) with injection of SH L 643A and 1.61 +/- 0.31 with injection of gadopentetate dimeglumine (P.01). In VX2 carcinomas, the enhancement ratios were not significantly different with injection of SH L 643A than with injection of gadopentetate dimeglumine at all time points. The mean difference between the enhancement ratios of the VX2 carcinomas and postoperative scars was 0.64 +/- 0.10 (range, 0.50-0.77) with SH L 643A and 0.36 +/- 0.16 (range, 0.17-0.66) with gadopentetate dimeglumine (P.01). The mean microvessel density (in terms of vessels per field of view) was 10.7 +/- 5.5 for postoperative scars and 30.0 +/- 7.7 for VX2 carcinoma (P.001).The difference between the enhancement ratios of postoperative scars and VX2 carcinomas with SH L 643A was greater than that with gadopentetate dimeglumine. Enhancement ratios at SH L 643A-enhanced MR imaging corresponded well with microvessel density in postoperative scars and VX2 carcinomas.

The feasibility of a method of magnetic resonance (MR)-guided sclerotherapy for hemangioma was evaluated. The distribution of a test injection and a contiguous sclerosant injection was monitored clearly with MR fluoroscopy. Postsclerotherapy T2-weighted MR images depicted areas with and those without effective sclerosant concentration, which enabled performance of selective supplemental sclerotherapy. This method of MR-guided sclerotherapy seems feasible for clinical application.

Axillary lymph node status is the most important prognostic factor in breast cancer patients and is currently determined by surgical dissection. This study was performed to assess whether dynamic gadopentetate dimeglumine (Gd) enhanced MRI is an accurate method for non-invasive staging of the axilla. 47 women with a new primary breast cancer underwent pre-operative dynamic Gd enhanced MRI of the ipsilateral axilla. Lymph node enhancement was quantitatively analysed using a region of interest method. Enhancement indices and nodal area were compared with histopathology of excised nodes using a receiver operating characteristic (ROC) curve approach. 10 patients had axillary metastases pathologically and all hador =1 lymph node with an enhancement index of21% and a nodal area of0.4 cm(2). 37 patients had negative axillary nodes pathologically. 20 of these had enhancement indices21% and nodal areas0.4 cm(2). Using this method, a sensitivity of 100%, a specificity of 56%, a positive predictive value of 38% and a negative predictive value of 100% could be achieved. Using this method of quantitative assessment, dynamic Gd enhanced MRI may be a reliable method of predicting absence of axillary nodal metastases in women with breast cancer, thereby avoiding axillary surgery in women with a negative MRI study.

The accumulation of gadolinium loaded as gadopentetic acid (Gd-DTPA) in chitosan nanoparticles (Gd-nanoCPs), which were designed for gadolinium neutron-capture therapy (Gd-NCT) for cancer, was evaluated in vitro in cultured cells. Using L929 fibroblast cells, the Gd accumulation for 12 h at 37 degrees C was investigated at Gd concentrations lower than 40 ppm. The accumulation leveled above 20 ppm and reached 18.0+/-2.7 (mean+/-S.D.) microg Gd/10(6) cells at 40 ppm. Furthermore, the corresponding accumulations in B16F10 melanoma cells and SCC-VII squamous cell carcinoma, which were used in the previous Gd-NCT trials in vivo, were 27.1+/-2.9 and 59.8+/-9.8 microg Gd/10(6) cells, respectively, hence explaining the superior growth-suppression in the in vivo trials using SCC-VII cells. The accumulation of Gd-nanoCPs in these cells was 100-200 times higher in comparison to dimeglumine gadopentetate aqueous solution (Magnevist), a magnetic resonance imaging contrast agent. The endocytic uptake of Gd-nanoCPs, strongly holding Gd-DTPA, was suggested from transmission electron microscopy and comparative studies at 4 degrees C and with the solution system. These findings indicated that Gd-nanoCPs had a high affinity to the cells, probably contributing to the long retention of Gd in tumor tissue and leading to the significant suppression of tumor growth in the in vivo studies that were previously reported.

The effect of Gd-DTPA on T-1-weighted choline signal in human brain tumours. The influence of Gd-DTPA on T-1-weighted (T1W) proton MR spectra has been investigated in 19 patients with histologically verified low (n = 13) or high-grade (n = 6) gliomas. Repeat measurements were performed on 9 patients (7 low-grade and 2 high-grade), with 28 examinations performed in total. Comparison of spectra obtained before and after 0.2 mmol/kg Gd-DTPA showed contrast agent induced broadening of the choline signal without significant signal area change. Lack of enhancement of the choline signal with the T-1-weighted acquisitions implies that the contrast agent and the trimethylamine-containing species do not undergo significant direct interaction. Contrast agent induced changes in the choline signal observed in this and previous studies may, therefore, be attributable to T2*/susceptibility-based effects.

To investigate whether time-resolved imaging with interleaved stochastic trajectories (TWIST)-volumetric interpolated breath-hold examination (VIBE) hepatic arterial phase imaging technique improves image quality in patients experiencing transient severe motion (TSM) during abdominal magnetic resonance imaging (MRI) with gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA).This retrospective study compares TSM in MRI images from 28 patients with focal liver lesions imaged with gadopentetic acid (Gd-DTPA) and 28 patients with focal liver lesions imaged with Gd-EOB-DTPA. Images were taken during the precontrast phase, five hepatic arterial phases acquired with a single breath-hold, portal venous phase, and late dynamic phase.There was a significant difference in the mean motion scores for the arterial phase in Gd-EOB-DTPA cohort before, and after, enhancement (p0.001); however, there was no significant difference in the Gd-DTPA cohort for the same (p0.05). The mean motion scores in the five hepatic arterial phases in the Gd-EOB-DTPA cohort after enhancement were significantly higher than that in the Gd-DTPA cohort (p0.001). TSM occurred significantly more frequently in the Gd-EOB-DTPA cohort (64.2%) than in the Gd-DTPA cohort (3.5%, p0.001). The highest motion score in Gd-EOB-DTPA cohort occurred during the fourth arterial phase, which was significantly higher than the other four arterial phases after enhancement (p0.001). Moderate and severe TSM (motion score ≥3) occurred mainly in the mid and mid-late arterial phase. All patients with arterial phase images affected by TSM (motion scores ≥3) had at least one arterial phase image with TSM score3, which was of adequate image quality for diagnostic purposes.The TWIST-VIBE hepatic arterial phase imaging technique can be used to acquire arterial images at abdominal MRI with Gd-EOB-DTPA, and these images have adequate quality for diagnosis in patients who are affected by TSM.

Magnetic resonance imaging (MRI) is used extensively for clinical diagnoses. It is critical to design and develop highly efficient MR contrast agents with simple preparation procedure, low toxicity, and high biocompatibility. Here, we report a carbon quantum dots (CQDs)-stabilized gadolinium hybrid nanoprobe (Gd-CQDs) prepared via a one-pot hydrothermal treatment of the mixture of citrate acid, ethanediamine, and GdCl3 at 200 degrees C for 4 h. In vitro and in vivo tests confirmed their low toxicity and high biocompatibility. Gd-CQDs were observed to have a higher MR response than gadopentetic acid dimeglumine (Gd-DTPA) because of their high Gd content and hydrophilicity. Moreover, the fluorescence of CQDs was remained in Gd-CQDs. The in vivo MR and fluorescence dual-modality imaging of Gd-CQDs was confirmed with zebrafish embryo and mice as models. The modification of Gd-CQDs with arginine-glycine-aspartic acid (RGD) tripeptide provided a high affinity to U87 cancer cells for targeted imaging. Whereas the MR response showed a depth penetration and spatial visualization, fluorescence revealed the fine distribution of Gd-CQDs in tissues because of its high resolution and sensitivity. We found that Gd-CQDs distributed in the tissues in a heterogeneous mode: they entered into the tissue cells but were observed less in the extracellular matrix. The MR and fluorescence dual-modality imaging of Gd-CQDs makes them a potential contrast agent for clinic applications because of their simple preparation procedure, ease of functionalization, high contrast efficiency, low toxicity, and high biocompatibility.

The purpose of this study was to compare aerosolized gadoteridol and gadopentetate dimeglumine in regard to homogeneity of aerosol distribution and relative pulmonary signal intensity (SI) changes after a 10-min mechanical ventilation period. Twenty experimental procedures were performed in 10 intubated domestic pigs that were mechanically aerosolized with the nebulized contrast medium. Images were obtained by using a respiratory-gated T1-weighted TSE sequence. Pulmonary SI increase for the right and left lung was 26% ± 25% and 25% ± 12%, respectively, for gadopentetate dimeglumine, and 45% ± 12% and 43% ± 10%, respectively, for gadoteridol. Aerosol distribution was rated homogeneous in all cases by two readers. It is concluded that both contrast agents in aerosolized form are capable of depicting pulmonary ventilation in healthy animals with lung capacities comparable to those of humans. SI differences between gadoteridol and gadopentetate dimeglumine are explained by their considerable difference in viscosity. Magn Reson Med 46:803–806, 2001. © 2001 Wiley-Liss, Inc.

To evaluate whether the vascular system resulting from an arterial lesion shows differences in permeability to a tracer with respect to the normal vascular system and whether eventual differences are maintained for long periods.Permanent ischemia was induced in rats with femoral arterial removal, and magnetic resonance (MR) imaging was performed after 1, 7, 14, and 90 days. Gadopentetate dimeglumine was injected, and the kinetics of its penetration in the leg were studied. Phosphorus 31 spectroscopy was performed to determine the bioenergetic characteristics of the gastrocnemius muscle at rest and stimulation. Ischemic muscles were then processed for electron microscopy.After ischemia induction, a hyperintense area that progressively decreased was present on T2-weighted images. Gadopentetate dimeglumine improved the signal intensity of the area. Three months after arterial occlusion, the contrast-enhanced images still showed microvessels highly permeable to the tracers. Spectroscopic data revealed that 3 months after arterial removal, the bioenergetic reserve of the gastrocnemius muscle was reduced, suggesting that the contrast-enhanced MR imaging-visible area is functionally relevant. Ultrastructural examination revealed persistent muscle damage and signs of chronic microangiopathy.After ischemia induction, the restitutio ad integrum is not complete, and delayed muscle injuries can result from arterial insufficiency.

Purpose: To increase specificity of MR-mammography by using dynamic T 2 * sequences. Methods: 23 patients with suspicious lesions of the breast underwent conventional dynamic T 1 -weighted (T 1 -dynamic) breast MRI and, subsequently, dynamic T 2 * -weighted (T 2 * -dynamic) perfusion studies. To assess the T 1 -dynamic, signal enhancement during the first minute (E 1 ) was calculated. To evaluate the T 2 * -dynamic, relative signal intensity loss after administration of contrast medium was determined. Results: After administration of contrast medium, 6 of 13 malignant lesions did not show a signal decrease during the T 2 * -dynamic. Two of them exhibited an atypical signal enhancement in the T 1 -dynamic, with E 1 100%), which is more typical for malignant lesions. Discussion: The use of dynamic T 2 * sequences, following dynamic T 1 -weighted breast MRI and administration of contrast medium, does not sufficiently increase diagnostic sensitivity. Thus, this study does not support the potential advantage of susceptibility MR imaging for a further characterization of breast lesions.

Purpose: To study the incidence of adverse events after i.v. injection of MR contrast agents in a Chinese population. A comparison was made between an ionic contrast agent (dimeglumine gadopentetate, Magnevist) and a non-ionic contrast agent (gadodiamide, Omniscan). Material and Methods: During a 24-month period, 2,049 Chinese patients who randomly received an i.v. bolus injection of either Magnevist or Omniscan were investigated. All patients were questioned for the presence of any generalized or localized adverse reaction on the following day after the MR examination according to a standardized questionnaire. Results: Three hundred and nine out of 2,049 patients (15%) reported an adverse event. There was a higher incidence of adverse events in patients receiving Magnevist as compared to those receiving Omniscan injection. All reported adverse events were clinically mild and required neither treatment nor hospitalization. Conclusion: There was a higher incidence of adverse reaction in patients receiving Magnevist than in those receiving Omniscan.

Objective: To evaluate the usefulness of sequential T2-weighted spin-echo type multishot echo-planar (T2-EP) imaging with gadopentetate dimeglumine for the detection of hypovascular metastatic liver tumors. Material and Methods: Fifteen consecutive patients with 56 proven hypovascular metastatic liver tumors were included in the study. Three observers blindly and independently read the whole-liver images obtained with T2-weighted spin-echo, T2-weighted single-shot fast spin-echo, T1-weighted fast multiplanar spoiled GRASS and T2-EP images obtained before and 25, 60, 90 and 120 s after injection of 0.2 mmol/kg b.w. of gadopentetate dimeglumine. The diagnostic accuracy was estimated by calculating the area under the observer-specific binomial receiver operating characteristics curves (Az). Results: T2-EP images obtained 60 s after contrast injection showed significantly higher contrast-to-noise (C/N) ratios than the other imaging techniques. A combination of all phases of the T2-EP images produced the highest sensitivity and specificity. In terms of the Az value, the diagnostic accuracy for tumor detection achieved with a combination of all phases of the T2-EP images was significantly higher than that with T1-SPGR and T2-SSFSE images ( p Conclusion: Our preliminary study revealed that sequential imaging with enhanced T2-EP images was useful for the detection of hypovascular metastatic liver tumors because of its superior C/N ratio and sensitivity.

Biodegradable gadopentetic acid (Gd-DTPA)-loaded chitosan microparticles (Gd-microCPs) were prepared as a device for gadolinium neutron-capture therapy (Gd-NCT) by a novel emulsion-droplet coalescence technique: a water-in-oil (w/o) emulsion A containing chitosan and Gd-DTPA in droplets and a w/o emulsion B containing NaOH in droplets were mixed and stirred to solidify chitosan as a result of collision and coalescence between droplets of each emulsion. Gd-microCPs prepared by using 100% deacetylated chitosan in 25% Gd-DTPA solution were 4.1 microns (non-lyophilized) and 3.3 microns (lyophilized) in mass median diameter, and were 3.4% in gadolinium content, corresponding to 11.7% as Gd-DTPA. The particle size and gadolinium content of Gd-microCPs were not affected by Gd-DTPA concentration in the chitosan medium. However, the deacetylation degree of chitosan influenced the particle size; as the deacetylation degree of chitosan decreased, the particle size increased. The incorporated Gd-DTPA was not released entirely from Gd-microCPs in an isotonic phosphate buffered saline solution despite the high water-solubility of Gd-DTPA (less than 0.8% with every type of Gd-microCPs). These results indicated that ion-complex formation might be contributable to incorporation of Gd-DTPA. As a preliminary study, it was confirmed that the loss of gamma-ray emission by gadolinium-loading in microparticle was negligible in the thermal neutron irradiation test in vitro. These results suggested that Gd-microCPs could be a useful device for intratumoral injection into solid tumor on Gd-NCT.

Purpose. The gadopentetic acid (Gd-DTPA)-loaded chitosan nanoparticles (Gd-nanoCPs) were prepared for gadolinium neutron-capture therapy (Gd-NCT) and characterized and evaluated as a device for intratumoral (i.t.) injection.

Gadolinium (Gd)-containing lecithin microcapsules were composed of a lactose core (75-90 μm) coated with polyvinylpyrrolidone (PVP), a drug layer of Gd compound and PVP, and a membrane consisting of soybean lecithin, cholesterol, stearic acid and PVP. As Gd compounds, gadopentetate dimeglumin (Gd-DTPA-DM, MC-1), gadopentetic acid (Gd-DTPA, MC-2) and a stearylamide derivative of Gd-DTPA (Gd-DTPA-SAm, MC-3) were used. The microcapsules were prepared with a high coating efficiency and a narrow size distribution, 149-177 μm. The release Gd-DTPA-DM and Gd-DTPA from MC-1 and MC-2, respectively, in a 0.9% saline solution was similar in spite of their difference in water solubility; it was delayed with a short lag time of about 10 min, followed by a rapid release and finally sustained; on the other hand, the release was remarkedly delayed and prolonged without the initial rapid release in the dextran solution. The release of water-insoluble Gd-DTPA-SAm was almost completely suppressed until 120 min in both aqueous solutions (MC-3). In the saline solution, all types of Gd-containing microcapsules were bursting devices at the initial stage, accompanying the delayed but high particle swelling, and thereafter diffusion-controlled drug-release devices. In the viscous dextran solution, they remained diffusion-controlled drug-release devices due to poor water uptake and poor swelling. These results suggested the possibility for using Gd-containing lecithin microcapsules in Gd neutron-capture therapy.

STUDY DESIGN A comparison of contrast enhancement in the intervertebral disc from two magnetic resonance imaging contrast media in experimental animals. OBJECTIVES To test the effect of molecular weight on the diffusion of ionic contrast media into the intervertebral disc. SUMMARY OF BACKGROUND DATA Intravenously administered gadopentetate diffuses similarly into the fibrocartilage of intervertebral discs and herniated disc fragments. Differentiation between recurrent disc fragments and scar tissue via magnetic resonance imaging is optimized by using contrast media, which result in different contrast enhancement of these two tissues. Contrast media of higher molecular weight diffuse more slowly into cartilage; hypothetically, therefore, such media will produce better contrast between scar tissue and recurrent disc fragments. METHODS Gadopentetate (molecular weight 546) or gadolinium-polylysine (molecular weight 40,000) was injected intravenously into rabbits. The signal intensities of intervertebral disc and muscle tissue were recorded by magnetic resonance imaging at baseline and at pre-determined intervals for 2 hours after injection of the contrast medium. Contrast enhancement in these tissues was calculated in each animal for each contrast medium, and differences in enhancement were tested for significance by a growth-curve model. RESULTS Contrast enhancement in the intervertebral disc was significantly less with gadolinium-polylysine than with gadopentetate. In muscle, no significant difference between the two media was observed. CONCLUSIONS Molecular weight affects the diffusion of paramagnetic contrast media into the intervertebral disc. Contrast media of a high molecular weight may produce better contrast between recurrent herniated disc fragments and scar tissue than contrast media of lower molecular weight. This possibility should be rested in further studies.

Purpose Our goal was to determine the normal MR arthrographic appearance of the elbow and to identify the potential diagnostic pitfalls of this technique. Method MRI with intra-articularly administered gadopentetate dimeglumine was performed in seven elbow joints derived from cadavers. Coronal, sagittal, and axial SE T1-weighted images with fat suppression and coronal 3D SPGR images with fat suppression were obtained in each elbow. The elbows were then sectioned. Results This technique allowed depiction of the cartilaginous surfaces of the elbow joint as well as clear delineation of the inner surface of the collateral ligaments. Potential diagnostic pitfalls included fat pads projecting into the joint, synovial folds, and cartilaginous pseudoerosions. Conclusion MR arthrography allows clear delineation of the intraarticular structures of the elbow. However, diagnostic pitfalls exist that increase the difficulty of interpreting MR arthrographic images.

Purpose: To study the usefulness of dynamic magnetic resonance imaging in the evaluation of head and neck cancers treated with radiation therapy. Methods and Materials: Seventy-six patients (58 males and 18 females; ages 20-82) with head and neck cancers (10 nasopharyngeal carcinomas, 22 mesopharyngeal carcinomas, 10 hypopharyngeal carcinomas, 16 oral cavity carcinomas, 11 lingual carcinomas, and 7 laryngeal carcinomas) were treated by radiation therapy combined with concomitant low-dose cisplatinum. Magnetic resonance imaging (MRI) was performed before and 2 weeks after the irradiation in all cases. After bolus administration of gadopentetate dimeglumine (Gd-DTPA) (0.1 mmol/ kg), images were obtained every 30 s (repetition time 200 ms, echo time 16 ms) using a 1.5 or 0.5-T superconductive unit. Biopsy or surgery was performed after radiation therapy and the histologic findings were correlated with the MRI findings (T 1 , T 2 , dynamic, and enhanced T,). Results: Complete remission, partial response, and no response were obtained in 18, 36, and 7 cases, respectively. Dynamic MRI correctly diagnosed 17 of the 18 complete remission cases, 33 of the 36 partial response cases, and all of the 7 no-response cases. The accuracy of dynamic MRI, T 1 -weighted image, T 2 -weighted image, and Gd-enhanced T 1 -weighted image was 94.4%, 68%, 82%, and 86%, respectively. Conclusion: Dynamic MRI proved to be useful in the evaluation of the radiation therapy of head and neck cancers.

Background Cerebral sparganosis in children is an extremely rare disease of central nervous system, and caused by a tapeworm larva from the genus of Spirometra. In this study, we discussed and summarized epidemiological, clinical and MR imaging characteristics of eighteen children with cerebral sparganosis for a better diagnosis and treatment of the disease. Methods Eighteen children with cerebral sparganosis verified by pathology, serological tests and MR presentations were retrospectively investigated, and the epidemiologic and clinical characteristics of the disease were studied. Results Twenty-seven lesions were found in the eighteen children. Twelve lesions in twelve patients were solitary while the lesions in the rest six patients were multiple and asymmetrical. The positions of the lesions were: seven in frontal, eleven in parietal, four in temporal and two in occipital lobes, one in basal ganglia, one in cerebella hemisphere and one in pons. The lesions were presented as slight hypointensity on T1-weighted images but moderate hyperintensity on T2-weighted images with perilesional brain parenchyma edema. Enhanced MR scans by using Gadopentetic Acid Dimeglumine Salt were performed in the patients, and the images demonstrated abnormal enhancements with the patterns of a peripheral ring, or a tortuous beaded, or a serpiginous tubular shape. Follow-up MR scans were preformed for eight patients, and three out of the eight cases exposed migrations and changes in shapes of the lesion areas. Conclusions The MR presentations in our study in general were similar to those in previous studies. However serpiginous tubular and comma-shaped enhancements of lesions have not been previously reported. The enhanced MR imaging and follow-up MR scans with the positive results from serological tests are the most important methods for the clinical diagnosis of cerebral sparganosis in children.