bluuebunny/crossref_metadata_2025 huggingface dataset:
Alteration of the insulin‐like growth factor axis during in vitro differentiation of the human osteosarcoma cell line HOS 58
Authors: Viereck Volker , Siggelkow Heide , Pannem Rajeswararao , Braulke Thomas , Scharf Jens‐Gerd , Kübler Bernd
Published: March 2007

The insulin‐like growth factors I and II (IGF‐I, IGF‐II), their receptors, and high affinity binding proteins (IGFBPs) represent a family of cellular modulators that play essential roles in the development and differentiation of cells and tissues including the skeleton. Recently, the human osteosarcoma cell line HOS 58 cells were used as an in vitro model of osteoblast differentiation characterized by (i) a rapid proliferation rate in low‐density cells that decreased continuously with time of culture and (ii) an increasing secretion of matrix proteins during their in vitro differentiation. In the present paper, HOS 58 cells with low cell density at early time points of the in vitro differentiation (i) displayed a low expression of IGF‐I and ‐II; (ii) synthesized low levels of IGFBP‐2, ‐3, ‐4, and ‐5, but (iii) showed high expression levels of both the type I and II IGF receptors. During the in vitro differentiation of HOS 58 cells, IGF‐I and ‐II expressions increased continuously in parallel with an upregulation of IGFBP‐2, ‐3, ‐4, and ‐5 whereas the IGF‐I receptor and IGF‐II/M6P receptor mRNA were downregulated. In conclusion, the high proliferative activity in low cell density HOS 58 cells was associated with high mRNA levels of the IGF‐IR, but low concentrations of IGFBP‐2. The rate of proliferation of HOS 58 cells continuously decreased during cultivation in parallel with a decline in IGF‐IR expression, but increase of mitoinhibitory IGFBP‐2. These data are indicative for a role of the IGF axis during the in vitro differentiation of HOS 58 cells. J. Cell. Biochem. 102: 28–40, 2007. © 2007 Wiley‐Liss, Inc.
An ROS generator, antimycin A, inhibits the growth of HeLa cells via apoptosis
Authors: Park Woo Hyun , Han Yong Whan , Kim Suhn Hee , Kim Sung Zoo
Published: March 2007

Antimycin A (AMA), an inhibitor of electron transport in mitochondria, has been used as a reactive oxygen species (ROS) generator in biological systems. Here, we investigated the in vitro effect of AMA on apoptosis in HeLa cells. AMA inhibited the growth of HeLa cells with an IC50 of about 50 µM. AMA efficiently induced apoptosis, as evidenced by flow cytometric detection of sub‐G1 DNA content, annexin V binding assay, and DAPI staining. This apoptotic process was accompanied by the loss of mitochondrial membrane potential (ΔΨm), Bcl‐2 down‐regulation, Bax up‐regulation, and PARP degradation. All caspase inhibitors used in this experiment, especially pan‐caspase inhibitor (Z‐VAD), could rescue some HeLa cells from AMA‐induced cell death. When we examined the changes of the ROS, H2O2 or O, in AMA‐treated cells, H2O2 and O were markedly increased. In addition, we detected the depletion of GSH content in AMA‐treated cells. Pan‐caspase inhibitor showing the efficient anti‐apoptotic effect significantly reduced GSH depletion by AMA. Superoxide dismutase (SOD) and catalase did not reduce intracellular ROS, but these could strongly rescue the cells from apoptosis. However, these anti‐apoptotic effects were not accompanied by the recovery of GSH depletion. Interestingly, catalase significantly decreased the CMF negative (GSH depletion) and propidium iodide (PI) positive cells, indicating that catalase strongly maintained the integrity of the cell membrane in CMF negative cells. Taken together, these results demonstrate that AMA potently generates ROS, induces the depletion of GSH content in HeLa cells, and strongly inhibits the growth of HeLa cells throughout apoptosis. J. Cell. Biochem. 102: 98–109, 2007. © 2007 Wiley‐Liss, Inc.
Akt2, but not Akt1 or Akt3 mediates pressure‐stimulated serum‐opsonized latex bead phagocytosis through activating mTOR and p70 S6 kinase
Authors: Shiratsuchi Hiroe , Basson Marc D.
Published: March 2007

Monocytes and macrophages play critical roles in innate host defense and are sensitive to mechanical stimuli. Tissue pressure is often altered in association with inflammation or infection. Low pressure (20 mmHg), equivalent to normal tissue pressure, increases phagocytosis by primary monocytes and PMA‐differentiated THP‐1 macrophages, in part by FAK and ERK inhibition and p38 activation. PI‐3K is required for macrophage phagocytosis, but whether PI‐3K mediates pressure‐stimulated phagocytosis is not known. Furthermore, little is known about the role played by the PI‐3K downstream Kinases, Akt, and p70 S6 kinase (p70S6K) in modulating macrophage phagocytosis. Thus, we studied the contribution of PI‐3K, Akt, and p70S6K to pressure‐increased serum‐opsonized bead phagocytosis. Pressure‐induced p85 PI‐3K translocation from cytosolic to membrane fractions and increased Akt activation by 36.1 ± 12.0% in THP‐1 macrophages. LY294002 or Akt inhibitor IV abrogated pressure‐stimulated but not basal phagocytosis. Basal Akt activation was inhibited 90% by LY294002 and 70% by Akt inhibitor IV. Each inhibitor prevented Akt activation by pressure. SiRNA targeted to Akt1, Akt2, or Akt3 reduced Akt1, Akt2, and Akt3 expression by 50%, 45%, and 40%, respectively. However, only Akt2SiRNA abrogated the pressure‐stimulated phagocytosis without affecting basal. Pressure also activated mTOR and p70S6K. mTORSiRNA and p70S6K inhibition by rapamycin or p70S6KSiRNA blocked pressure‐induced, but not basal, phagocytosis. Changes in tissue pressure during inflammation may regulate macrophage phagocytosis by activation of PI‐3K, which activates Akt2, mTOR, and p70S6K. J. Cell. Biochem. 102: 353–367, 2007. © 2007 Wiley‐Liss, Inc.
Androgen receptor stimulates bone sialoprotein (BSP) gene transcription via cAMP response element and activator protein 1/glucocorticoid response elements
Authors: Takai Hideki , Nakayama Youhei , Kim Dong‐Soon , Arai Masato , Araki Shouta , Mezawa Masaru , Nakajima Yu , Kato Naoko , Masunaga Hiroshi , Ogata Yorimasa
Published: March 2007

Bone sialoprotein (BSP) is an early marker of osteoblast differentiation. Androgens are steroid hormones that are essential for skeletal development. The androgen receptor (AR) is a transcription factor and a member of the steroid receptor superfamily that plays an important role in male sexual differentiation and prostate cell proliferation. To determine the molecular mechanism involved in the stimulation of bone formation, we have analyzed the effects of androgens and AR effects on BSP gene transcription. AR protein levels were increased after AR overexpression in ROS17/2.8 cells. BSP mRNA levels were increased by AR overexpression. However, the endogenous and overexpressed BSP mRNA levels were not changed by DHT (10−8 M, 24 h). Whereas luciferase (LUC) activities in all constructs, including a short construct (nts −116 to +60), were increased by AR overexpression, the basal and LUC activities enhanced by AR overexpression were not induced by DHT (10−8M, 24 h). The effect of AR overexpression was abrogated by 2 bp mutations in either the cAMP response element (CRE) or activator protein 1 (AP1)/glucocorticoid response element (GRE). Gel shift analyses showed that AR overexpression increased binding to the CRE and AP1/GRE elements. Notably, the CRE‐protein complexes were supershifted by phospho‐CREB antibody, and CREB, c‐Fos, c‐Jun, and AR antibodies disrupted the complexes formation. The AP1/GRE‐protein complexes were supershifted by c‐Fos antibody and c‐Jun, and AR antibodies disrupted the complexes formation. These studies demonstrate that AR stimulates BSP gene transcription by targeting the CRE and AP1/GRE elements in the promoter of the rat BSP gene. J. Cell. Biochem. 102: 240–251, 2007. © 2007 Wiley‐Liss, Inc.
Quantitative MR imaging of children with sickle cell disease: Striking T1 elevation in the thalamus
Authors: Steen R. Grant , Langston James W. , Reddick Wilburn E. , Ogg Robert , Chen Gang , Wang Winfred C.
Published: March 2007

Nineteen patients with sickle cell disease (SCD) were examined with conventional MR imaging (cMRI), including T1‐ and T2‐weighted sequences and MR angiography (MRA). qMRI mapping of T1 was also done using a precise and accurate inversion‐recovery (PAIR) technique optimized and validated previously. In addition, 21 healthy African‐American control subjects had the qMRI examination. Nonparametric Kruskal‐Wallis analysis of variance of control subjects, of SCD patients without stroke, and of SCD patients with stroke showed that T1 increased with disease severity in the thalamus, frontal white matter, genu, and occipital white matter. T1 was significantly longer in SCD patients without stroke (n=13) than in control subjects (n=21) in the thalamus and frontal white matter. In addition, T1 values were significantly longer in SCD patients with stroke than in patients without stroke in the genu and frontal white matter. Abnormality of the thalamus was identified by qMRI in a substantial fraction of patients read as normal by both cMRI and MRA, suggesting that it may be possible to use T1 elevation to identify a subset of patients with SCD who are at elevated risk for stroke.
Statistical error mapping for reliable quantitative T1 imaging
Authors: Reddick Wilburn E. , Ogg Robert J. , Steen R. Grant , Taylor June S.
Published: March 2007

We developed a statistically based error image for rapid appreciation of unreliable regions in quantitative water proton T1 images. The chi‐squared error and coefficient of variation of the fitted parameter were used to estimate uncertainties in the goodness‐of‐fit to monoexponential T1 relaxation and the reliability of the calculated T1, respectively, for each pixel. Errors exceeding a statistical threshold based on a .1 acceptance criterion were displayed as a color‐coded overlay on the T1 image. Error maps of quantitative T1 images from 31 healthy volunteers showed a characteristic error structure; few pixels within the parenchyma had excessive errors. Clinical cases with stroke and sickle cell disease showed deviations from the normal pattern in the spatial distribution and magnitude of chisquared errors. Disease states may deviate from monoexponential T1 relaxation more than normal brain does. The color‐coded error map is a valuable tool for investigators using quantitative MR imaging to determine tissue relaxation parameters.
Prospective comparison of helical CT and MR imaging in clinically suspected acute pulmonary embolism
Authors: Sostman H. Dirk , Layish Daniel T. , Tapson Victor F. , Spritzer Charles E. , Delong David M. , Trotter Priscilla , Macfall James R. , Patz Edward F. , Goodman Philip C. , Woodard Pamela K. , Foo Thomas K. F. , Farber Joshua L.
Published: March 2007

The purpose of this study is to compare sensitivity and specificity of helical CT and MR imaging for detecting acute pulmonary embolism (PE). Patients who were suspected clinically of having PE were randomly assigned to undergo either helical contrast‐enhanced CT or gradient‐echo MR (if one modality was contraindicated, the patient was assigned to the other). Patients were considered to have PE if they had: (1) high‐probability V‐Q scan and high clinical probability of PE; or (2) pulmonary angiogram positive for PE. Patients were considered not to have PE if they had either: (1) normal V‐Q scan; (2) low probability V‐Q scan and low clinical probability of PE; or (3) pulmonary angiogram negative for PE. The CT and MR images were read randomly and independently by five radiologists with varying levels of CT and MR experience. Twenty eight patients underwent CT and 25 MR. A total of 21 patients underwent pulmonary angiography (6 had PE, 15 did not have PE). Of the other 32 patients, 15 had high probability scan/high clinical probability and 17 had low probability scan/low clinical probability. For the five observers, the average sensitivity of CT was 75% and of MR 46%; the average specificity of CT was 89% and of MR 90%. Experience with vascular MR and enhanced CT influenced diagnostic accuracy. For the two vascular MR experts, average sensitivity and specificity of MR were 71% and 97%, and of CT 73% and 97%. In this pilot study, when CT and MR were interpreted with comparable expertise, they had similar accuracy for detecting pulmonary embolism.
Malignant lesions of the liver with high signal intensity on T1‐Weighted MR images
Authors: Kelekis Nikolaos L. , Semelka Richard C. , Woosley John T.
Published: March 2007

Our purpose was to identify the histologic types of malignant liver lesions with high signal intensity (SI) on T1‐weighted images and to describe the MR imaging features. Thirteen patients with malignant liver lesions high in SI on T1‐weighted images were studied with a 1.5‐T MR imager using pre‐ and serial postcontrast spoiled gradient‐echo (SGE) sequences (all patients), T2‐weighted fat‐suppressed spin‐echo sequences (all patients), precontrast T1‐weighted fat‐suppressed spin‐echo sequences (five studies in five patients), and precontrast out‐of‐phase SGE sequences (seven studies in six patients). Images were reviewed retrospectively to determine number of lesions; lesion size; SI of lesions on T1‐weighted, T2‐weighted, and fat‐attenuated T1‐weighted images; distribution of high SI in lesions on T1‐weighted images; and tumor enhancement pattern. Seven patients had multiple tumors high in SI on T1‐weighted images and six patients had solitary tumors. Seventy‐two lesions were less than 1.5 cm in diameter and 35 lesions were more than 1.5 cm in diameter. Nine patients had solid malignant lesions and four patients had cystic malignant lesions. All tumors more than 1.5 cm in diameter were heterogeneously high in SI on T1‐weighted images, and all tumors less than 1.5 cm were completely homogeneous or homogeneous with a small central hypointense focus. All tumors were more conspicuous on T1‐weighted fat‐attenuated images, both on excitation spoiled fat‐suppressed spin‐echo or on out‐of‐phase SGE images with the exception of one fat‐containing hepatocellular carcinoma (HCC). In one patient with melanoma metastases and one patient with multiple myeloma nodules, appreciably more lesions were detected on out‐of‐phase SGE images. Causes of hyperintensity were considered to be either fat, melanin, central hemorrhage, or high protein content, all of which may be seen in a variety of tumors. Fat‐attenuation techniques are helpful in the detection of these lesions.
Evaluation of the effects of intravascular MR contrast media (gadolinium dendrimer) on 3D time of flight magnetic resonance angiography of the body
Authors: Bourne Michael W. , Margerun Larry , Hylton Nola , Campion Brian , Lai Jan‐Ji , Derugin Nikita , Higgins Charles B.
Published: March 2007

The aims of this preliminary study were to establish the efficacy and minimum effective dose of TG5(FdDO3A)52 gadolinium dendrimer for contrast‐enhanced, three‐dimensional (3D) time of flight (TOF) magnetic resonance angiography (MRA) of the body. In a dose ranging study in eight rabbits (Group A), each of two animals received 0.03; 0.02; 0.01; or 0.005 mmol/kg of the agent for 3D‐TOF MRA of the pelvic circulation in the axial and coronal planes. An additional nine animals (Group B) received a dose of 0.02 mmol/kg for 3D‐TOF MRA of the mediastinum, abdomen or of the lower limbs. Quantitative and qualitative analyses of the images from Group A demonstrated a dose‐related reduction in saturation effects and improved visualization of vascular structures, with maximal augmentation of the contrast‐to‐noise ratio (CNR) at 0.03 mmol/kg. The dose of 0.02 mmol/kg was found to be the minimal effective dose at the three vascular regions.
Gamekeeper thumb: Diagnosis of ulnar collateral ligament injury using magnetic resonance imaging, magnetic resonance arthrography and stress radiography
Authors: Harper Michael T. , Chandnani Vijay P. , Spaeth Joseph , Santangelo James R. , Providence Bertram C. , Bagg Mark A.
Published: March 2007

Ulnar collateral ligament (UCL) tears may be nondisplaced or displaced relative to the adductor pollicis aponeurosis. Nondisplaced tears typically heal with immobilization whereas displaced tears require surgery. Nineteen patients with UCL injuries were evaluated using MR imaging (MRI), MR arthrography, and stress radiography (SR) to determine the efficacy of these techniques in differentiating nondisplaced from displaced UCL tears. Nineteen patients with UCL injuries were evaluated. MRI was utilized in 5 patients, and MR arthrography in 14, with 12 of these 14 undergoing SR. They were followed until resolution of symptoms; those without relief, and those with suspected displaced UCL tears were surgically explored. Surgery and imaging was correlated. Eight patients underwent surgical repair. SR was abnormal in six patients treated surgically, but was negative in four of six conservatively treated patients with MR findings of nondisplaced tears. All patients with MR or MR arthrographic findings interpreted as being normal or as having a nondisplaced tear improved after conservative treatment. Based on surgical findings and clinical follow‐up, MR arthrography accurately diagnosed 13 of 14 UCL injuries, with one false‐positive interpretation. SR is often falsely negative. MR imaging with or without intra‐articular contrast injection proved to be accurate in a small series of patients with UCL injuries.
Optimization of a dual echo in the steady state (DESS) free‐precession sequence for imaging cartilage
Authors: Hardy Peter A. , Recht Michael P. , Piraino David , Thomasson David
Published: March 2007

Three‐dimensional (3D) MR imaging of the knee is useful to detect cartilage abnormalities, although the tissue contrast in 3D gradient‐recalled echo (GRE) sequences such as gradient‐recalled acquisition in the steady state (GRASS) or fast low‐angle shot (FLASH) is poor. T2 contrast can be added to a GRASS sequence by combining the signals from the first and second gradient echoes, which form immediately after and immediately before each radiofrequency (RF) pulse in a 3D GRE sequence. We have optimized a 3D dual echo in the steady state (DESS) sequence, which produces one averaged image from the two echoes, for use in the detection of articular cartilage abnormalities. In the optimization process, we examined the imaging parameters of flip angle (α), repetition time (TR), echo time (TE), and bandwidth to maximize the contrast between cartilage and joint fluid. A theoretical simulation of the sequence was confirmed with experiments conducted on phantoms with known T1 and T2. On the basis of theoretical predictions and experiments using healthy volunteers, we determined that an optimized sequence with a bandwidth of 98 Hz per pixel, a TR of 30 msec, a TE of 7.1 msec, and an α of 60° produced the highest contrast between cartilage and fluid within a defined acquisition time of 6 minutes. Additional contrast was obtained by filtering the second‐echo image to eliminate noise before adding it to the first‐echo image.
Theoretical and experimental evaluation of phase‐dispersion effects caused by brain motion in diffusion and perfusion MR imaging
Authors: Wirestam Ronnie , Greitz Dan , Thomsen Carsten , Brockstedt Sara , Olsson Magnus B. E. , Ståhlberg Freddy
Published: March 2007

We investigated intravoxel phase dispersion caused by pulsatile brain motion in diffusion spin‐echo pulse sequences. Mathematical models were used to describe the spatial and temporal velocity distributions of human brain motion. The spatial distribution of brain‐tissue velocity introduces a phase spread over one voxel, leading to signal loss. This signal loss was estimated theoretically, and effects on observed diffusion coefficient and perfused capillary fraction were assessed. When parameters from a diffusion pulse sequence without motion compensation were used, and ECG triggering with inappropriate delay times was assumed, the maximal signal loss caused by brain‐motion‐induced phase dispersion was predicted to be 21%. This corresponds to a 95% overestimation of the diffusion coefficient, and the perfusion‐fraction error was small. Corresponding calculations for motion‐compensated pulse sequences predicted a 1% to 1.5% signal loss due to undesired phase dispersion, whereas experimental results indicated a signal loss related to brain motion of 4%.
Hepatocellular carcinoma exhibiting a concentric structure of different histologic grades: Evaluation by chondroitin sulfate iron colloid‐enhanced MR imaging
Authors: Kamba Masayuki , Suto Yuji , Kodama Fumiko , Ohta Yoshio , Kobayashi Junko , Horie Yutaka , Kawasaki Hironaka
Published: March 2007

A patient with hepatocellular carcinoma exhibiting a concentric structure of different histologic grades was examined with chondroitin sulfate iron colloid (CSIC)‐enhanced MR imaging. After CSIC injection, the advanced component was enhanced in comparison with the surrounding liver, and the well‐differentiated component was not enhanced. CSIC‐enhanced MR imaging was helpful in evaluating histologic grade on the basis of reticuloendothelial function.
Dynamic MRI of the gallbladder lesions: Differentiation of benign from malignant
Authors: Yoshimitsu Kengo , Honda Hiroshi , Kaneko Kuniyuki , Kuroiwa Toshiro , Irie Hiroyuki , Ueki Takashi , Chijiiwa Kazuo , Takenaka Kenji , Masuda Kouji
Published: March 2007

Forty‐nine pathologically proven gallbladder lesions were evaluated in 45 patients using dynamic MRI with a spoiled gradient pulse sequence (SPGR), to access the ability of this technique to differentiate benign from malignant gallbladder lesions. The studies were reviewed retrospectively. Signal intensity of the lesions were measured. Twenty‐one malignant and 28 benign lesions were classified into three categories: polypoid, diffuse wall thickening, and exophytic. Early and delayed enhancement patterns were evaluated. For the polypoid masses, malignant lesions (n = 9) demonstrated early and prolonged enhancements, whereas benign lesions (n = 14) had early enhancement with subsequent washout (P < .05). For diffuse gallbladder wall thickening, malignant lesions (n = 6) demonstrated early and prolonged enhancement and benign lesions (n = 14) showed relatively slow, prolonged enhancement (P < .05). The exophytic masses (n = 6) all were malignant and demonstrated early and prolonged enhancement. Dynamic MRI can help differentiate benign from malignant gallbladder lesions.
Analysis of magnetization transfer effects on T1‐weighted spin‐echo scans using a simple tissue phantom simulating gadolinium‐enhanced brain lesions
Authors: Finelli Daniel A. , Hurst Gregory C. , Frank Holly A. , Gullapali Rao P. , Apicella Anthony
Published: March 2007

The purpose of this study was to analyze the effect of several magnetization transfer (MT) pulse and T1‐weighted spin‐echo (SE) sequence parameters on lesion‐to‐background contrast, using a simple tissue phantom emulating the T1 relaxation and MT properties of gadolinium‐enhanced brain lesions. Eggbeaters (Nabisco Inc., East Hanover, NJ) liquid egg product was doped with gadolinium in six concentrations from .0 to 1.0 mmol and cooked. The gadolinium‐doped egg phantom and normal volunteer brains were studied using an SE sequence with TE = 20 msec and high power, pulsed, off‐resonance MT saturation. The effects of MT pulse frequency offset (1,000–6,000 Hz), sequence repetition time (TR = 500–1,000 msec, with MT power held constant), and slice‐select flip angle (60–120 degrees) on the magnetization transfer ratio (MTR) and the simulated lesion‐to‐background contrast were determined at the different “Intralesion” gadolinium concentrations. The MTR and lesion‐to‐background contrast of all materials were greatest at narrow MT pulse frequency offsets. There was an inverse relationship between gadolinium concentration and MTR and a positive correlation between the gadolinium concentration and lesion‐to‐background (L/B) contrast, a weak negative correlation between slice‐select flip angle and L/B, and a negative correlation between TR and L/B. The relaxation properties and MT behavior of the egg phantom are close to that expected for enhancing brain lesions, allowing a rigorous analysis of several variables affecting lesion‐to‐background contrast for high MT power, T1‐weighted SE sequences.
Progression of a focal ischemic lesion in rat brain during treatment with a novel glycine/nmda antagonist: An in vivo three‐dimensional diffusion‐weighted MR microscopy study
Authors: Qiu Hui , Hedlund Laurence W. , Gewalt Sally L. , Benveniste Helene , Bare Thomas M. , Johnson G. Allan
Published: March 2007

Stroke was induced in two groups of anesthetized rats by occlusion of the middle cerebral artery (MCA) and ipsilateral common carotid artery. Group 1 (control) received vehicle and group 2 received the glycine N‐methyl‐D‐aspartate (NMDA) antagonist ZD9379. Stroke volume was assessed by three‐dimensional diffusion‐weighted MR microscopy at 2.5 and 6 hours of MCA occlusion. At 2.5 hours, stroke volumes were identical in the two groups. At 6 hours, stroke volumes had increased by 15% in the control group; in contrast, the treated group showed a 40% reduced stroke volume. Conclusions from this in vivo study were as follows: (a) our technique allows more efficient and accurate measurement of stroke volume with an improvement in resolution over a previous method; (b) the ability to measure stroke volume at multiple time points shows volume change and assessment of time dependency of drug treatment; (c) at 6 hours, the glycine antagonist ZD9379 reduced stroke volume by 40%.
Paradoxic uptake of Gd‐EOB‐DTPA by hepatocellular carcinoma in mice: Quantitative image analysis
Authors: Fujita Makoto , Yamamoto Reiko , Takahashi Masaya , Tsuji Takashi , Yamanaka Tsuyoshi , Miyazawa Tomoaki , Fritz‐Zieroth Bernhard , Terada Nobuyuki , Kuroda Chikazumi
Published: March 2007

To determine whether paradoxic uptake of gadoliniumethoxybenzyl‐diethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA) occurs only with highly differentiated hepatocellular carcinomas, quantitative image analysis was performed in 37 mice with 133 hepatocellular carcinomas. The results of lesion/liver signal intensity measurement and relative enhancement calculation indicate that paradoxic positive enhancement occurs independently of cellular differentiation.
Adaptive correction of imaging plane position in segmented K‐space cine cardiac MRI
Authors: Chuang Michael L. , Chen Ming Hui , Khasgiwala Vaibhav C. , McConnell Michael V. , Edelman Robert R. , Manning Warren J.
Published: March 2007

Variability among breath‐holds frequently produces registration errors, a situation that may contribute to reproducibility error in anatomic indices. A navigator‐echo‐based method for real‐time prospective correction of imaging slice level was applied to breath‐hold cine cardiac imaging of 13 subjects. Repeat acquisitions with correction in the cardiac short‐axis orientation showed significantly improved reproducibility in fractional area change and endocardial centroid location as compared with conventional noncorrected methods.
Segmental hyperintensity on T1‐weighted MRI of the liver: Indication of segmental cholestasis
Authors: Gabata Toshifumi , Matsui Osamu , Kadoya Masumi , Yoshikawa Jun , Ueda Kazuhiko , Kawamori Yasuhiro , Takashima Tsutomu
Published: March 2007

The purpose of this study was to determine the relationship between segmental hyperintensity of the liver on T1‐weighted images and segmental cholestasis in patients with obstructive jaundice. T1‐weighted and T2‐weighted MR images were obtained of 73 patients with obstructive jaundice caused by various diseases. Fat‐suppressed T1‐weighted images were also obtained of 10 patients. Eleven patients with segmental intra‐hepatic bile duct dilatation (cholestasis) showed segmental hyperintensity on T1‐weighted images and/or fat‐suppressed T1‐weighted images and no signal intensity difference on T2‐weighted images. Sixty‐two patients with widespread intrahepatic bile duct dilatation showed no intensity difference on T1‐weighted and T2‐weighted images (P < .01). Segmental hyperintensity on T1‐weighted images was correlated with intrahepatic cholestasis.
Improvement of spiral MRI with the measured k‐space trajectory
Authors: Ding Xiaoping , Tkach Jean , Ruggieri Paul , Perl John , Masaryk Thomas
Published: March 2007

The k‐space trajectory of a spiral imaging sequence was measured with a self‐encoding technique. The image quality improved dramatically when reconstructed with the measured k‐space trajectory. There were substantial artifacts in images reconstructed with the derived k‐space trajectory under the assumption of gradient system linearity. The results indicated the non‐linearity of the gradient system and the effectiveness of the correction technique.
Multiresolution, model‐based segmentation of MR angiograms
Authors: Summers Paul E. , Bhalerao Abhir H. , Hawkes David J.
Published: March 2007

During the last decade, the quality of MR angiograms has risen substantially and their clinical utility has been demonstrated progressively. This acceptance has created a need for tools with which to summarize and display the information available. We have used a model‐based segmentation technique to extract vascular morphology and local flow parameters from phase contrast MR angiograms. A multiresolution data structure is used as the basis of recursive decision‐making to identify regions of blood flow. The resulting data representation allows more efficient data handling in subsequent processing and visualization and is directly applicable to the creation of a connected graph model of vascular regions. We describe this flow feature extraction algorithm and demonstrate the utility of the results.
Ultrasmall superparamagnetic iron oxide particles (AMI 227) as a blood pool contrast agent for MR angiography: Experimental study in rabbits
Authors: Loubeyre Pierre , Zhao Shihua , Canet Emmanuelle , Abidi Hassane , Benderbous Soraya , Revel Didier
Published: March 2007

The purpose of this study was to evaluate the contribution of an ultrasmall superparamagnetic iron oxide particles (USPIOs) based contrast agent (AMI 227), in a transverse three‐dimensional time‐of‐flight TONE MR angiography sequence of abdominal aorta in rabbits. The main goal was to assess improvement in the visualization of small arteries such as renal arteries, when using such a sequence. Imaging experiments were performed on a 1.5 T magnet, using a transverse 3D time‐of‐flight (TOF) tilted optimized nonsaturating excitation (TONE) sequence with magnetization transfer suppression. The contrast media used were composed of a USPIO core surrounded by a dextransurfactant (AMI 227). Different concentrations of AMI 227 were evaluated in 12 rabbits. Concentrations varied within the range 8.5–34 μmol Fe/kg‐bw: 8.5 μmol Fe/kg (three rabbits); 17 μmol Fe/kg (three rabbits); 25.5 μmol Fe/kg (three rabbits); 34 μmol Fe/kg (three rabbits). A visual analysis based on the improvement of visualization of small arteries (renal arteries) on MIP images and a quantitative analysis based on the percentage of contrast enhancement of the aorta plotted against distance in the slab from the top edge of the acquisition volume were obtained. A signal‐to‐noise ratio enhancement of the distal part of the aorta and only improvement in the delineation of the renal arteries were noted when using low concentrations of the contrast media. A loss of signal‐to‐noise ratio of the aorta and a decrease in arterial visualization were respectively noted with higher concentration of contrast media. In this experimental study, using a transverse three‐dimensional TOF TONE MR angiography sequence of renal arteries, in which sequence the saturation effect is minimized, the use of AMI 227 allows only improvement in the delineation.
MRI of pelvic masses: Efficacy of the rectal superparamagnetic contrast agent ferumoxsil
Authors: Scheidler Juergen , Heuck Andreas F. , Meier Werner , Reiser Maximilian F.
Published: March 2007

The purpose of this study was to determine the potential value of rectally administered Ferumoxsil for pelvic MRI. Twenty patients with suspected rectosigmoid and ovarian tumors were prospectively examined before and after rectal administration of 300 to 600 ml of the superparamagnetic contrast agent Ferumoxsil. Imaging parameters (1.5‐T system, phased‐array coil, transverse T1‐weighted spin echo (SE) and T2‐weighted turbo‐SE sequences, 6‐mm slice thickness, 350‐mm field of view [FOV], 512 × 512 matrix) were kept constant. Images were evaluated for tumor presence, lymphadenopathy, bowel involvement, and peritoneal implants. Precontrast and postcontrast studies were rated for bowel delineation, lesion/organ‐to‐bowel differentiation, presence of artifacts, and confidence of diagnosis. Delineation of rectum and sigmoid colon (P < .001) as well as separation of bowel and vagina, uterus/adnexa, dome of the urinary bladder, lymph nodes, and vessels improved significantly (P < .01) on both T1‐weighted and T2‐weighted postcontrast sequences. The rectal contrast agent did not increase the level of artifacts. Changes in diagnosis in 7 of 20 patients were mainly due to identification of colorectal tumors or bowel involvement on postcontrast images. The readers' diagnostic confidence was significantly higher on contrast‐enhanced than on unenhanced studies (93 ± 6.4% vs 68 ± 25.2%). Rectal application of Ferumoxsil improves lesion/organ‐to‐bowel delineation and overall diagnostic confidence in pelvic MRI.
Rapidly enhancing hepatic hemangiomas at MRI: Distinction from malignancies with T2‐weighted images
Authors: Outwater Eric K. , Ito Katsuyoshi , Siegelman Evan , Martin C. Edwin , Bhatia Manoj , Mitchell Donald G.
Published: March 2007

The purpose of this study is to describe a subset of atypical hepatic hemangiomas that enhance rapidly and diffusely and to determine whether heavily T2‐weighted images could distinguish between atypically enhancing liver hemangiomas and hypervascular malignancies. A retrospective search of MR records identified seven patients with liver hemangiomas that demonstrated diffuse early enhancement and 23 patients with biopsy‐proven malignant liver lesions that were hypervascular on dynamic gadolinium‐enhanced MR images. Quantitative analysis of signal intensity measurements was performed on the T2‐weighted images, heavily T2‐weighted (TE < 140), and dynamic gadolinium‐enhanced images. Blinded reader comparison of the T2‐weighted images and gadolinium‐enhanced images was performed. Hypervascular hemangiomas enhanced to a greater degree than hypervascular malignant liver lesions on the early phase gadolinium‐enhanced images. Perilesional parenchymal enhancement was demonstrated in five cases of rapidly enhancing hemangiomas. Signal intensity and contrast‐to‐noise ratios on the heavily T2‐weighted images of the hemangiomas were significantly greater than that of the hypervascular malignant lesions (P < .05). Hemangiomas were differentiated from the hypervascular malignant liver lesions with high accuracy (97–100%) by three blinded readers based on the T2‐weighted images. A subset of hemangiomas have atypical rapid diffuse enhancement on dynamic gadolinium‐enhanced images. These atypical hemangiomas can be distinguished from hypervascular malignant liver lesions on T2‐weighted MR images.
Liver lesion detection, characterization, and effect on patient management: Comparison of single‐phase spiral CT and current MR techniques
Authors: Semelka Richard C. , Worawattanakul Suvipapun , Kelekis Nikolaos L. , John Gesine , Woosley John T. , Graham Mark , Cance William G.
Published: March 2007

This study compares liver lesion detection, characterization, and effect on patient management between single‐phase spiral CT and MRI using spoiled gradient echo (SGE), T2‐weighted fat‐suppressed spin echo, and serial post gadolinium SGE. All patients with suspected liver lesions who underwent spiral CT and MRI within a 1‐month period between January 1993 and September 1996 were included in the study. Spiral CT and MRI were interpreted prospectively in a blinded fashion by separate individual experienced investigators, and lesion detection and characterization were determined. Confirmation was obtained by surgery (6 patients), biopsy (18 patients), imaging follow‐up (36 patients), or combined reading of all imaging studies and clinical follow‐up (29 patients). Effect on patient management was determined by combined chart review and interview of the patients' physicians and by retrospective clinical assessment performed by a surgical oncologist and medical oncologist separately. Eighty‐nine patients were included in the study. Regarding true positive lesion detection, 295 and 519 lesions were detected on spiral CT and MR images, respectively, which was significantly different on a patient‐by‐patient basis (P < .001). More lesions were detected on MR than on spiral CT in 44 of 89 patients (49.4%), and 11 of these 44 patients had lesions shown on MRI in whom no lesions were apparent on CT images. No patients had true positive lesions shown on spiral CT that were not shown on MRI. Regarding lesion characterization, 129 and 466 lesions were characterized on spiral CT and MRI images, respectively, which was significantly different on a patient‐by‐patient basis (P < .001). More lesions were characterized on MR than CT images in 67 patients (75.3%). Regarding effect on patient management, chart review with physician interview demonstrated that findings on MRI provided information that altered patient management as compared with findings on spiral CT in 57 patients. Retrospective clinical evaluation by the surgical and medical oncologist showed that MRI was considered to have a greater effect on patient management than spiral CT in 58 and 55 patients, respectively. Comparing current MRI technique to single‐phase spiral CT, MRI detected more lesions in 49.4% and characterized more lesions in 75.3% of patients investigated for focal liver disease. MRI had a greater effect on patient management in each of the three methods than singlephase spiral CT in more than 61% of patients.
The effects of incomplete breath‐holding on 3D MR Image Quality
Authors: Maki Jeffrey H. , Chenevert Thomas L. , Prince Martin R.
Published: March 2007

The purpose of this study was to investigate how fast three‐dimensional (3D) MR image quality is affected by breath‐holding and to develop an optimal breath‐holding strategy that minimizes artifact in the event of an incomplete breath‐hold. A computer model was developed to study variable‐duration breath‐holds during fast 3D imaging. Modeling was validated by 3D gradient‐echo imaging performed on 10 volunteers. Signal‐to‐noise ratio (SNR) and image blur were measured for both simulated and clinical images. Insights gained were applied to clinical 3D gadolinium‐enhanced MR angiography. Breath‐holding significantly improved abdominal 3D MR image quality. Most of this benefit could be achieved with a breath‐hold fraction of 50% if it occurred during acquisition of central k space. Breath‐holding during peripheral k‐space acquisition, however, had no significant benefit. Respiratory motion artifact on fast 3D MRI occurring when a patient fails to suspend respiration for the entire scan duration can be minimized by collecting central k space first (centric acquisition) so that premature breathing affects only the acquisition of peripheral k space.
Uptake of dextran‐coated monocrystalline iron oxides in tumor cells and macrophages
Authors: Moore Anna , Weissleder Ralph , Bogdanov Alexei
Published: March 2007

Although several dextran‐coated iron oxide preparations are in preclinical and clinical use, little is known about the mechanism of uptake into cells. As these particles have been shown to accumulate in macrophages and tumor cells, we performed cellular uptake and inhibition studies with a prototypical monocrystalline iron oxide nanoparticle (MION). MION particles were labeled with fluorescein isothiocyanate or radioiodinated and purified by gel permeation chromatography. Two preparations of MION particles were used in cell experiments: nontreated MION and plasma‐opsonized MION purified by gradient density purification. As determined by immunoblotting, opsonization resulted in C3, vitro‐nectin, and fibronectin association with MION. Incubation of cells with fluorescent MION showed active uptake of particles in macrophages both before and after opsonization. In C6 tumor cells, however, intracellular MION was only detectable in dividing cells. Quantitatively, 125I‐labeled MION was internalized into cells with uptake values ranging from 17 ng (in 9L gliosarcoma) to 970 ng iron per million cells for peritoneal macrophages. Opsonization increased MION uptake into macrophages sixfold, whereas it increased the uptake in C6 tumor cells only twofold. Results from uptake inhibition assay suggest that cellular uptake of nonopsonized (dextran‐coated) MION particles is mediated by fluid‐phase endocytosis, whereas receptor‐mediated endocytosis is presumably responsible for the uptake of opsonized (protein‐coated) particles.
Invited. Interactive MRI‐guided radiofrequency interstitial thermal ablation of abdominal tumors: Clinical trial for evaluation of safety and feasibility
Authors: Lewin Jonathan S. , Connell Cindy F. , Duerk Jeffrey L. , Chung Yiu‐Cho , Clampitt Mark E. , Spisak Julie , Gazelle G. Scott , Haaga John R.
Published: March 2007

This clinical trial was performed to evaluate the safety and feasibility of interactive MR‐guided radiofrequency (RF) interstitial thermal ablation (ITA) performed entirely within the MR imager. RF‐ITA was performed on 11 intra‐abdominal metastatic tumors during 13 sessions. The RF electrode was placed under MR guidance on a .2‐T system using rapid fast imaging with steady state precession (FISP) and true FISP images. A custom 17‐gauge electrode was used and was modified in four sessions to allow circulation of iced saline for cooling during ablation. Tissue necrosis monitoring and electrode repositioning were based on rapid T2‐weighted and short‐inversion‐time inversion recovery (STIR) sequences. Morbidity and toxicity were assessed by clinical and imaging criteria. The region of tissue destruction was visible in all 11 tumors treated, as confirmed on subsequent contrast‐enhanced images. No significant morbidity was noted, and patient discomfort was minimal. In conclusion, interactive MR‐guided RF‐ITA is feasible on a clinical .2‐T C‐arm system with supplemental interventional accessories with only minor patient morbidity. The ability to completely ablate tumors with RF‐ITA depends on tumor size and vascularity.
Treatment planning for MRI‐guided laser‐induced interstitial thermotherapy of brain tumors—The role of blood perfusion
Authors: Schwarzmaier Hans‐Joachim , Yaroslavsky Ilya V. , Yaroslavsky Anna N. , Fiedler Volkhard , Ulrich Frank , Kahn Thomas
Published: March 2007

MR techniques have been demonstrated to allow a reliable monitoring of laser‐induced interstitial thermotherapy (LITT). However, an adequate on‐line control of this coagulation technique requires an exact therapy planning. The latter is mandatory to interpret the MR‐monitoring data correctly to guarantee a precise laser irradiation. Moreover, it is a prerequisite for online decisions if modifications of the therapeutic regimen are required. In this work, we present a new simulation technique for LITT planning. The model accounts for the specific geometry of the treatment site, the exact configuration of the applicator, and the optical and thermal properties of the tissue, including changes during the heating process. The simulation results were compared with MR scans of laser‐induced lesions in three patients with World Health Organization (WHO) grade II astrocytoma. Special interest was directed toward the role of blood perfusion, which was studied parametrically. Good agreement between the simulation results and the MR data was found if the appropriate blood perfusion rates were taken into account. Thus, the model can generate valid therapy plans allowing a precise on‐line control of laser irradiation using MR techniques. Neglecting adequate perfusion parameters resulted in substantial errors with respect to the prediction of the final laser lesion.
MRI monitoring of interstitial microwave‐induced heating and thermal lesions in rabbit brain in vivo
Authors: Moriarty John A. , Chen Julian C. , Purcell Carrie M. , Ang Lee C. , Hinks R. Scott , Peters Robert D. , Henkelman R. Mark , Plewes Donald B. , Bronskill Michael J. , Kucharczyk Walter
Published: March 2007

The purpose of this experiment was to use MRI to monitor microwave heating and thermal damage of brain tissue in vivo. Interstitial microwave antennas were implanted into the cerebral hemispheres of seven anesthetized rabbits. Variable power of 30 to 100 W was applied for periods of 5 to 15 minutes and tissue temperature was monitored continuously. MR images were obtained throughout the procedure at 20‐second intervals, using a spoiled gradient‐echo sequence, without significant artifact. Magnitude, phase, and complex difference images all demonstrated temperature‐related signal changes during heating. The findings were better visualized on the phase and complex difference images. Phase difference image analysis revealed an approximately linear relationship between phase change and temperature. Post‐treatment thermal lesions measured up to 2.0 cm in size on pathologic specimens and exhibited a zonal pattern on spin‐echo MR images.
Invited. In vivo MRI thermometry using a phase‐sensitive sequence: Preliminary experience during MRI‐guided laser‐induced interstitial thermotherapy of brain tumors
Authors: Kahn Thomas , Harth Thorsten , Kiwit Jürgen C. W. , Schwarzmaier Hans‐Joachim , Wald Christoph , Mödder Ulrich
Published: March 2007

The purpose of this study was the application of the proton‐resonance‐frequency method to monitor laser‐induced interstitial thermotherapy (LITT) in a patient with an astrocytoma WHO II. A phase‐sensitive two‐dimensional (2D) fast low‐angle shot (FLASH) sequence was used to determine the temperature‐related phase shifts during LITT. Temperature maps were displayed during therapy with a temporal resolution of 20 seconds. Irradiation was discontinued as soon as the 60 to 65°C isotherm reached the margin of the tumor. A contrast‐enhanced MRI study performed immediately after therapy showed a good correlation of the size of an enhancing rim around the lesion with the 60 to 65°C isotherm. The preliminary results of our study indicate that MRI guidance of LITT may be improved by temperature quantification based on the proton‐resonance‐frequency method.
Three‐dimensional monitoring of small temperature changes for therapeutic hyperthermia using MR
Authors: Wlodarczyk Waldemar , Boroschewski Ralf , Hentschel Michael , Wust Peter , Mönich Gerhard , Felix Roland
Published: March 2007

Radiofrequency hyperthermia of deep‐seated pelvic tumors requires noninvasive monitoring of temperature distributions in patients. Methods of MR thermography were reported to be a promising tool in solving this problem. However, to be truly useful for monitoring hyperthermia treatments, MR thermography should be able to cover the entire pelvis in acquisition times no longer than for a breath‐hold (⩽15 seconds) and to resolve small temperature differences (< 1°C). Three methods exploiting the temperature dependence of spin‐lattice relaxation time (T1), of self‐diffusion coefficient (D), and of chemical shift of proton resonance frequency (PRF) were applied in phantom experiments; the pulse sequences were the T1‐weighted gradient echo, the pulsed diffusion gradient spin echo made faster through the keyhole technique, and the gradient echo with the phase reconstruction, respectively. The high planar resolution was compromised, and instead, coarse and more isotropic voxels were used. Experiments were performed in two consecutive steps, thus imitating a possible scenario for monitoring hyperthermia. In the first step, calibration curves were recorded, which were then used in the second step to obtain maps of temperature changes. The results show a clear superiority of the PRF method, followed by the D and the T1 methods. The uncertainty of temperature changes predicted both from calibration curves and from maps was less than 1°C only with the PRF and the D‐based methods.