bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of MR cholangiopancreatography at .5 T: Three‐dimensional half‐averaged single‐shot fast spin echo with multi‐breath‐hold technique
Authors: Ichikawa Tomoaki , Haradome Hiroki , Hanaoka Hideto , Kassai Yosimori , Nitatori Toshiaki , Hachiya Junichi , Araki Tsutomu 
Published: March 2007

AbstractThe purpose of this study was to determine the advantage of a three‐dimensional (3D) single‐shot fast‐spin‐echo (SSFSE) sequence to obtain MR cholangiopancreatography (MRCP) with a .5‐T MR unit by comparison with a two‐dimensional (2D) SSFSE sequence. MRCP with 2D‐SSFSE and with 3D‐SSFSE with 128 echo train lengths was performed on 15 volunteers and 38 patients with pancreatobiliary disease using a .5‐T MR unit. For maximum intensity projection (MIP) reconstruction, the section thickness of source images was 4 mm in the 2D‐SSFSE and 3 mm in the 3D‐SSFSE. 3D volume data in 3D‐SSFSE were obtained using repeated short breath‐hold of 2 seconds for every repetition time throughout the examination. The image quality, duct conspicuity, signal‐intensity ratio (SIR), and contrast‐to‐noise ratio (CNR) were evaluated. In 23 of the patients who underwent both MRCP and direct cholangiopancreatography (endoscopic retrograde cholangiopancreatography [ERCP]/percutaneous transhepatic cholangiography [PTC]), a comparison between these two modalities was also conducted. The image quality of the MIP image with 3D‐SSFSE (49 of 53, 92.5% graded excellent or good) was superior to that with 2D‐SSFSE (31 of 53, 58.4%). Duct conspicuity, SIR, and CNR were significantly higher with 3D‐SSFSE than with 2D‐SSFSE. 3D‐SSFSE also showed a stronger relationship with the ERCP/PTC findings compared to 2D‐SSFSE. 3D‐SSFSE provided satisfactory quality, SIR, and CNR of MRCP images, even when a .5‐T MR unit was used, because the breath‐hold technique used during 3D data sampling minimized all types of motion effects.
Measurement of magnetization transfer in different stages of neurocysticercosis
Authors: Kathuria Manoj K. , Gupta Rakesh K. , Roy R. , Gaur Vandana , Husain N. , Pradhan Sunil 
Published: March 2007

AbstractThe purpose of this study was to establish magnetization transfer ratio (MTR) in different stages of neurocysticercosis. A total 2,532 cysticerci were studied prospectively in 15 cases. MTR from different regions of the lesions (ie, the cyst, the protoscolex or mural nodule, the granuloma wall) were calculated in different stages of evolution/degeneration in all cases. Of a total 2,532 lesions studied, 2,261 (89.29%) were seen on routine spin‐echo (SE) imaging. The rest of the lesions were only seen on magnetization transfer (MT) SE imaging. Maximum MTR was calculated from healing lesions (mean + SD = 31.0 ± 2.8) and from the core of SE invisible lesions (30.0 ± 5.1). Innocuous cystic lesions, which were hyperintense on T2‐weighted images, did not show any MT (MTR = 5.10 ± 1.2), whereas degenerating T2 hyperintense lesions showed MTR of 26.40 ± 2.7. Nondegenerating and degenerating scolices showed an intermediate MTR of 21.7 ± 3.3 and 15.0 ± 4.5, respectively. MT varies between different parts of the lesion and also from the same part in different stages of evolution/degeneration of the lesion. The visibility of a lesion on MT‐SE sequence was dependent on its MTR and its location at a particular site (cortical gray matter, white matter, or deep gray matter). The difference in MTR of the lesion and the surrounding brain parenchyma decides the resulting contrast and visibility of the lesion.
A reproducible method for automated extraction of brain volumes from 3D human head mr images
Authors: Wang Deming , Galloway Graham J. , de Zubicaray Greig I. , Rose Stephen E. , Chalk Jonathan B. , Doddrell David M. , Semple James 
Published: March 2007

AbstractAn automated method for extracting brain volumes from three commonly acquired three‐dimensional (3D) MR images (proton density, T1 weighted, and T2‐weighted) of the human head is described. The procedure is divided into four levels: preprocessing, segmentation, scalp removal, and postprocessing. A user‐provided reference point is the sole operator‐dependent input required. The method's parameters were first optimized and then fixed and applied to 30 repeat data sets from 15 normal older adult subjects to investigate its reproducibility. Percent differences between total brain volumes (TBVs) for the subjects' repeated data sets ranged from .5% to 2.2%. We conclude that the method is both robust and reproducible and has the potential for wide application.
Throwing injury of the elbow: Assessment with gradient three‐dimensional, Fourier transform gradient‐echo and short tau inversion recovery images
Authors: Sugimoto Hideharu , Hyodoh Kazusa , Shinozaki Takeshi 
Published: March 2007

AbstractWe assessed MR findings of throwing injuries occurring in the elbow joint using three‐dimensional Fourier transform (3DFT) and short tau inversion recovery (STIR) images. MR images of 63 elbows in 63 male patients aged from 10 to 32 years (mean age, 15 years 11 months) suffering from throwing injury were visually analyzed. The sequences used for the study were axial 3DFT and coronal STIR. Full‐thickness tears were demonstrated in 34 elbows and undersurface tears of the ulnar collateral ligament (UCL) were demonstrated in five elbows. Thirty loose bodies were detected in 14 elbows. Cartilaginous damage due to osteochondral injury was depicted in 21 elbows. Multiplanar reformatted images using the 3DFT data set were useful for assessing torn UCLs, intraarticular loose bodies, and capitellar fragments. Full‐thickness tears and undersurface tears of the UCL could be differentiated with STIR images. 3DFT and STIR sequences depict various aspects of throwing injuries occurring in the elbow.
Can MRCP replace ERCP?
Authors: Takehara Yasuo 
Published: March 2007

AbstractMagnetic resonance cholangiopancreatography (MRCP) has replaced direct cholangiography and pancreatography in many instances. Its complete noninvasiveness and flexibility are less onerous for patients. For the use of screening as well as scrutiny, MRCP has played an important role in diagnosing various pathologies in this field. The usefulness of MRCP is not limited to anatomical evaluations; it can also yield physiologic and functional information. From a cost‐performance basis, MRCP is undoubtedly superior to direct methods. Coupled with a cutting‐edge MR system, MRCP has the potential to limit the use of invasive transpapillary and percutaneous methods merely to interventional purposes. In the near future, the emergence of interventional MR scanners will make MRCP even more competitive, and the replacement will be accelerated.
Quantitative MRI of the brain in children with sickle cell disease reveals abnormalities unseen by conventional MRI
Authors: Steen R. Grant , Reddick Wilburn E. , Mulhern Raymond K. , Langston James W. , Ogg Robert J. , Bieberich Andrea A. , Kingsley Peter B. , Wang Winfred C. 
Published: March 2007

AbstractConventional MRI (cMRI) has shown that brain abnormalities without clinical stroke can manifest in patients with sickle cell disease (SCD). We used quantitative MRI (qMRI) and psychometric testing to determine whether brain abnormalities can also be present in patients with SCD who appear normal on cMRI. Patients 4 years of age and older with no clinical evidence of stroke were stratified by cMRI as normal (n= 17) or abnormal (n= 13). Spin‐lattice relaxation time (T1) of gray and white matter structures was measured by the precise and accurate inversion recovery (PAIR) qMRI method. Patient cognitive ability was assessed with a standard psychometric instrument (WISC‐III or WISC‐R). In all 30 patients with SCD, qMRI T1 was lower than in 24 age‐ and race‐matched controls, in cortical gray matter (P< .0006) and caudate (P< .0009), as well as in the ratio of gray‐to‐white matter T1 (P< .008). In the 17 patients who were shown to be normal by cMRI, qMRI T1 was still lower than in controls, in both cortical gray matter (P< .02) and caudate (P< .004). Histograms of voxel T1 show that the proportion of voxels with T1 values intermediate between gray and white matter (ie, consistent with encephalomalacia) was 9% higher than controls in patients shown to be normal by cMRI (P< .05) and 15% higher than controls in patients shown to be abnormal by cMRI (P< .0005). The full scale intelligence quotient (FSIQ) of all patients with SCD was 75, compared to the FSIQ of 88 in a historical control group of patient siblings (P< .001). The FSIQ of patients shown to be normal by cMRI was 79, significantly lower than the FSIQ of patient siblings (P< .04). The FSIQ of 71 in patients shown to be abnormal by cMRI was significantly lower than both the patient siblings (P< .005) and the patients shown to be normal by cMRI (P< .04). Patients shown to be abnormal by cMRI scored lower than patients shown to be normal by cMRI, specifically on the subtests of vocabulary (P= .003) and information (P= .03). Cognitive impairment is thus significant, even in patients with SCD who were shown to be normal by cMRI, suggesting that cMRI may be insensitive to subtle neurologic damage that can be detected by qMRI. Because cognitive impairment can occur in children normal by cMRI, our findings imply that prophylactic therapy may be needed earlier in the course of SCD to mitigate neurologic damage.
Quantification of in‐plane motion of the coronary arteries during the cardiac cycle: Implications for acquisition window duration for MR flow quantification
Authors: Hofman Mark B. M. , Wickline Samuel A. , Lorenz Christine H. 
Published: March 2007

AbstractMotion of the coronary arteries during the heart cycle can result in image blurring and inaccurate flow quantification by MR. This condition applies particularly for longer acquisition windows that are typical of breath‐hold coronary flow measurements. To determine the sensitivity of the technique to in‐plane motion of different coronary arteries, the temporal variation in coronary position was measured in a plane perpendicular to the proximal portion of the vessel. The results indicated the presence of substantial displacement of the coronary arteries within the cardiac cycle, with a magnitude of motion approximately twice as large for the right as for the left coronary arteries. An estimation of the resulting vessel blurring was calculated, showing that the duration of the acquisition window for high spatial resolution coronary flow acquisitions should be less than 25 to 120 msec, depending on the specific coronary artery studied. In addition, these data specify optimal acquisition window placement for high resolution coronary angiography.
Value of image subtraction in 3D gadolinium‐enhanced MR angiography of the renal arteries
Authors: Leung Daniel A. , Pelkonen Pia , Hany Thomas F. , Zimmermann Gesine , Pfammatter Thomas , Debatin Jörg F. 
Published: March 2007

AbstractThe objective of this study was to evaluate quantitatively and qualitatively the effect of image subtraction on the image quality of three‐dimensional (3D) gadolinium‐enhanced MR angiograms of the renal arteries. Breath‐hold 3D gadolinium MR angiography (MRA) as well as conventional contrast angiography of the renal arteries was performed on 20 patients with suspected renovascular hypertension. MR angiograms were acquired before and during dynamic infusion of gadolinium‐diethylenetriamine pentaacetic acid (Gd‐DTPA). Contrast‐enhanced images were compared with images that had undergone voxel‐by‐voxel signal intensity subtraction of contrast‐enhanced data from precontrast data. One false positive finding for significant renal artery stenosis was recorded with MRA using conventional angiography as the gold standard. Image subtraction did not alter the diagnosis at MRA in any case. The mean contrast‐to‐noise ratio (CNR) was significantly higher (P < .05) on the subtraction MR angiograms compared to the nonsubtracted MR angiograms. There was no significant difference in the signal‐to‐noise ratio (SNR). Qualitative analysis revealed a significant improvement in image quality after image subtraction with respect to visualization of the distal renal arteries. In conclusion, image subtraction improves the quality of renal MRA in terms of both CNR and visualization of the distal renal arteries.
Contrast‐enhanced 3D‐TOF MRA of peripheral vessels: Intravascular versus extracellular MR contrast media
Authors: Engelbrecht Marc R. , Saeed Maythem , Wendland Michael F. , Canet Emmanuelle , Øksendal Audun N. , Higgins Charles B. 
Published: March 2007

AbstractMR contrast media have been used to improve MR angiography (MRA). Their effect has been particularly beneficial for extracranial MRA. This study evaluated the efficacy of a new formulation of ultrasmall super‐paramagnetic iron oxide particles (USPIO) on three‐dimensional (3D) time of flight (TOF) MRA in the pelvis and lower limb circulation. Each of six dogs received 3 mg/kg of USPIO and .2 mmol/kg of gadolinium‐dieth‐ylenetriamine pentaacetic acid (Gd‐DTPA) bis‐meth‐ylamide (BMA) by intravenous infusion on separate examinations. Precontrast and postcontrast 3D‐TOF MRA images of the lower extremities were acquired over the course of 45 minutes postinjection. Signal intensity (SI) was measured on axial views along the external iliac, femoral, and popliteal arteries. USPIO provided clear demarcation of the major primary, secondary, and tertiary vessels and the improved contrast‐to‐noise ratio (CNR) was maintained for 45 minutes. Gd‐DTPA‐BMA provided less signal enhancement than USPIO. The increase in CNR with this agent had significantly declined by 15 minutes after injection. The major vessels could no longer be visualized at 30 and 45 minutes after injection of Gd‐DTPA‐BMA. This study demonstrates the efficacy of USPIO as a contrast medium for 3D‐TOF MRA. It was concluded that USPIO provided effective and persistent enhancement of the peripheral vessels.
Three‐dimensional low dose gadolinium‐enhanced peripheral MR venography
Authors: Li Wei , David Vivek , Kaplan Richard , Edelman Robert R. 
Published: March 2007

AbstractOur initial experience with low dose contrast‐enhanced (LCE) peripheral MR venography (MRV) is presented. Five subjects were studied using three‐dimensional (3D) fast imaging with a steady‐state precession (FISP) sequence. A dose of 60 ml of gadopentetate dimeglumine diluted 1:20 was used. A tourniquet was applied during lower extremity MR venography. The venous anatomy was well depicted with the 3D LCE technique in all subjects. Compared to the two‐dimensional (2D) time‐of‐flight (TOF) technique, acquisition time of 3D LCE MRV was much shorter, images looked sharper, and more veins could be seen. It is not affected by in‐plane saturation and can be performed repeatedly because of the low dose of contrast. This technique holds promise for the detection of venous thrombosis and other disorders.
Determination of sample time for T1 measurement
Authors: Zhang Yantian , Yeung Hong N. , O'Donnell Matthew , Carson Paul L. 
Published: March 2007

AbstractIn spin‐lattice relaxation time measurements, the relaxation time T1 is estimated from measuring the longitudinal magnetization during its return to thermal equilibrium from an initial (nonequilibrium) state. T1 estimation error depends on a number of factors, including the sample spacing, number of sample points, target T1 range, etc. We describe here a sample‐time determination method based on the principles of optimal experimental design. A two‐parameter model and a more general three‐parameter model of the general T1 measurement experiment are used in this study. Both linear and power‐law sample spacing strategies are evaluated. The proposed method formulates the sample‐time determination problem in closed form expressions that allow for easy calculation of optimum sample times, if a prior T1 estimate or a probable T1 distribution over the target range is given. Valuable insights can be gained from evaluation of these expressions concerning the relationship of T1 estimation error and the sample spacing, number of sample points, target T1 range, etc.
Preclinical assessment of hepatocyte‐targeted MR contrast agents in stable human liver cell cultures
Authors: Reimer Peter , Bader Augustinus , Weissleder Ralph 
Published: March 2007

AbstractMuch effort has been expended in the search for hepatocyte‐specific MR contrast agents to improve the detection and characterization of liver tumors. The purpose of this study was to establish human hepatocyte cell cultures to preclinically assess hepatocytetargeted magnetopharmaceuticals. Cultured human hepatocytes were sandwiched between two layers of collagen preserving both hepatocyte function and morphology over prolonged period of time. Cultures (n = 37) were subsequently used to test different fluorescinated MR contrast agents. Plain and rhodaminated monocrystalline iron oxide particles (MION and MION‐rh) and asialoglycoprotein‐receptor‐specific rhodaminated asialofetuin coupled to MION (MION‐ASF‐rh) were prepared. Competition experiments of these agents were performed with D(+)‐galactose to study the specificity of galactose‐mediated cell uptake. To assess the impact of cell integrity on cell uptake, functional experiments with CCI4 were performed. Normal cell cultures showed significantly higher fluorescence light emission after incubation with hepatocyte‐di‐rected ASF‐MION‐rh than after incubation with MION‐rh. Competition experiments of ASF‐MION‐rh with galactose showed a dose‐dependent decrease of calibrated fluorescence light emission. Cell cultures treated with CCI4 demonstrated a dose‐dependent significant reduction of calibrated fluorescence light emission, indicating reduced uptake of ASF‐MION‐rh. Our data demonstrate that stable human hepatocyte cell cultures can be used to preclinically assess novel magnetopharmaceuticals. Different contrast agents may be directly compared to each other and may accelerate their preclinical design. Because the assay can be applied to cells from any species, it may represent an ideal test system before clinical trials of new cell‐directed MR contrast agents.
Small renal cell carcinoma: MRI with pathologic correlation
Authors: Shinmoto Hiroshi , Yuasa Yuji , Tanimoto Akihiro , Narimatsu Yoshiaki , Jinzaki Masahiro , Hiramatsu Kyoichi , Mukai Makio 
Published: March 2007

AbstractThe MRI features of small renal cell carcinomas (RCCs) were retrospectively reviewed and correlated with histology in 24 patients. MRI features on both T1‐ and T2‐weighted images were classified into hypointensity, isointensity, and hyperintensity. Each tumor was pathologically classified into four types: alveolar, papillary, tubular, and cystic. These findings were correlated with MR signal intensities. Alveolar tumors showed hypointensity to isointensity on T1‐weighted image and isointensity to hyperintensity on T2‐weighted image. In contrast, all papillary tumors showed hypointensity on T2‐weighted image. Four of six tumors with hypointensity on T2‐weighted image were caused by hemosiderin deposition, hemorrhage, and necrosis. However, there were two papillary RCCs that showed hypointensity on T2‐weighted image despite no hemosiderin deposition and no hemorrhage. We conclude that papillary RCC is associated with T2‐hypointense appearance as well as hemosiderin deposition, hemorrhage, and necrosis.
Structure‐activity relationship of macrocyclic and linear gadolinium chelates: Investigation of transmetallation effect on the zinc‐dependent metallopeptidase angiotensin‐converting enzyme
Authors: Corot Claire , Idee Jean‐Marc , Hentsch Anne‐Marie , Santus Robin , Mallet Catherine , Goulas Valérie , Bonnemain Bruno , Meyer Dominique 
Published: March 2007

AbstractTransmetallation between commercially available solutions of gadolinium (Gd) chelates and the zinc (Zn)‐dependent angiotensin‐converting enzyme (ACE) was investigated. In vitro, the strongest inhibitions were observed for the linear Gd complexes, Gd diethylene‐triamine pentaacetic acid (DTPA) bis‐methylamide (BMA) (IC50 = .016 ± .006 mmol/1) and Gd‐DTPA (IC50 = .350 ± .034 mmol/1). The two macrocycles Gd tetraazacyclododecane tetraacetic acid (DOTA) and Gd‐HP‐DO3A were similar and 400 times less active than Gd‐DTPA‐BMA. These effects were mainly due to the presence of free ligand for DTPA and calcium (Ca) chelate in the case of DTPA‐BMA because the addition of Zn2+ in the same quantities suppresses their inhibitory effects. In vivo, these two solutions of linear Gd chelates significantly inhibited ACE activity (Gd‐DTPA: 67 ± 9% versus baseline; and Gd‐DTPA‐BMA: 73 ± 2% versus baseline at the clinical dose of .1 mmol/kg), whereas no significant effect was observed for the two macrocyclic chelates Gd‐DOTA and Gd‐HP‐DO3A. Formulating the Gd chelate solution with either an excess of free ligand or Ca chelate (to decrease Gd3+ release) in the case of linear Gd chelate may have deleterious biologic consequences.
MRI of the cartilaginous epiphysis of the femoral head in the piglet hip after ischemic damage
Authors: Babyn Paul S. , Kim Harry K. W. , Gahunia Harpal K. , Lemaire Claude , Salter Robert B. , Fornasier Victor , Pritzker Kenneth P. H. 
Published: March 2007

AbstractMRI of the cartilaginous epiphysis (CE) of piglet femoral head was performed after ischemic damage to study the changes in the CE found on MRI and to correlate these changes with histologic findings. Avascular necrosis of the femoral head was induced with a suture ligature in nine piglets; one piglet was killed postoperatively on day 3 and on weeks 1, 2, 3, 4, 6, 7, and 8 (two piglets were killed on week 3). MRI of the ischemic and contralateral nonischemic hip joints were obtained with a 60‐mm field of view (low resolution MRI). Biopsy cores of the femoral heads were imaged with a 15‐mm field of view (high resolution MRI) and correlated with histologic sections. The CE for all operated hips, except for the 3‐day postoperative specimen, showed evidence of ischemic changes on histologic assessment; the severity of damage increased with time. The MRI appearance of ischemic and nonischemic CE was clearly different by 2 weeks after the operation. No trilaminar signal pattern was evident in the high resolution T2‐weighted (T2W) imaging of the ischemic CE from 2 weeks after the operation. In the 3‐ to 8‐week postoperative specimens, focal areas of low signal intensity on high resolution T1‐weighted (T1W) and T2W imaging corresponded to the areas of chondronecrosis found on histologic assessment. The regions of high signal intensity on T2W imaging corresponded to the areas of chondrocyte clusters with increased safranin‐O staining. High resolution MRI can demonstrate changes in the CE associated with ischemic injury and may have a role in the assessment of the CE and its development after ischemic injury.
Quantification of patellar tracking using kinematic MRI
Authors: Powers Christopher M. , Shellock Frank G. , Pfaff Martin 
Published: March 2007

AbstractThe purpose of this study was to describe a method to quantify dynamic patellar tracking using kinematic MRI (KMRI). Twelve normal females and three patients with patellofemoral pain participated. Imaging was performed with a 1.5‐T/64‐MHz MR system using a fast spoiled gradient‐recalled acquisition in the steady state (GRASS) pulse sequence. A nonferromagnetic positioning device permitted active, bilateral knee extension against resistance (15% bwt) from 45° knee flexion to full extension. Subjects were instructed to extend their knees at a rate of 9° per second, which allowed images to be obtained at 45°, 36°, 27°, 18°, 9°, and 0°. All images were assessed for medial/lateral patellar displacement, patellar tilt, and sulcus angle using a computer‐aided system. Normal patellar motion was characterized by medial movement from 45° to 18°, followed by a reversal toward lateral displacement from 18° to full extension. The results for patellar tilt revealed a tendency toward decreasing lateral tilt as the knee extended. Sulcus angle measurements indicated that the patella was moving to a more shallow portion of the trochlear groove (superiorly) during extension.