bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laser‐induced thermotherapy (LITT) of liver metastases: MR‐guided percutaneous insertion of an MRI‐compatible irrigated microcatheter system using a closed high‐field unit
Authors: Puls Ralf , Stroszczynski Christian , Gaffke Gunnar , Hosten Norbert , Felix Roland , Speck Ulrich 
Published: May 2003

AbstractPurposeTo evaluate the efficacy and safety of a new MRI‐compatible irrigated laser microcatheter system for thermal ablation of liver metastases.Material and MethodsThe new microcatheter system consists of a titanium needle with a diameter of 1.5 mm and a surrounding Teflon catheter with an outer diameter of 1.8 mm (5.5 F). In vitro laser‐induced coagulation of bovine liver tissue was performed to determine the optimal perfusion rate of cooling saline flow, maximum laser energy, and ablation time. Laser‐induced thermotherapy using the new microcatheter system, an Nd:YAG laser (Dornier), and a flexible laser light guide (Somatex GmbH, Berlin, Germany) was performed in 28 patients with liver metastases. Percutaneous insertion and positioning of multiple microcatheters in the lesion and monitoring of therapy was performed with a closed high‐field MRI scanner using T1‐weighted gradient‐echo sequences during breath‐hold.ResultsA perfusion rate of 0.75 mL/minute, a laser energy of 15 W, and an ablation time of 20 minutes were found suitable to achieve safe and sufficient ablation of metastatic tissue. The mean volume of induced coagulation in vitro was 23.9 mL. Ablation of liver metastases in patients was technically and clinically successful.ConclusionThe new microcatheter system allows for both catheter placement and monitoring of therapy using a single imaging modality. This shortens the procedure and enables more precise puncture and therapy of liver metastases. Due to the miniaturized design of the catheter and the real‐time monitoring, the procedure is minimally invasive and very well tolerated by patients. This new technique seems to be a safe and feasible alternative in treating liver metastases. J. Magn. Reson. Imaging 2003;17:663–670. © 2003 Wiley‐Liss, Inc.
Magnetic resonance imaging and proton MR spectroscopy of the brain in a patient with carbohydrate‐deficient glycoprotein syndrome type I
Authors: Takeuchi Mayumi , Harada Masafumi , Hisaoka Sonoka , Nishitani Hiromu , Mori Kenji , Sakama Minoru 
Published: May 2003

AbstractThis is a report on a case of carbohydrate‐deficient glycoprotein syndrome (CDGS) with neurological deficits. Magnetic resonance (MR) images showed remarkable atrophy of the cerebellum and brainstem, and hypointensity was seen in the pallidum on diffusion‐weighted images (DWI), suggesting deposits of metal substances. In the cerebellum, proton MR spectroscopy (MRS) showed decreased concentrations of N‐acetylaspartate and a complex of glutamine and glutamate (Glx) while the concentration of myo‐inositol was increased, indicating neuronal impairment and gliosis. In the parietal lobe, there was an increased concentration of Glx, possibly reflecting dysfunction caused by liver injury. J. Magn. Reson. Imaging 2003;17:722–725. © 2003 Wiley‐Liss, Inc.
Simple anatomical measurements do not correlate significantly to individual peripheral nerve stimulation thresholds as measured in MRI gradient coils
Authors: Chronik Blaine A. , Ramachandran Meena 
Published: May 2003

AbstractPurposeTo examine peripheral nerve stimulation (PNS) thresholds for normal human subjects in magnetic resonance imaging (MRI) gradient coils, and determine if observed thresholds could be predicted based on gross physiologic measurements.Materials and MethodsPNS thresholds for 21 healthy normal subjects were measured using a whole‐body gradient coil. Subjects were exposed to a trapezoidal echo‐planar imaging (EPI) gradient waveform and the total change in gradient strength (ΔG) required to cause PNS as a function of the duration of the gradient switching time (τ) were measured. Correlation coefficients and corresponding P values were calculated for the PNS threshold measurements against simple physiologic measurements taken of the subjects, including weight, height, girth, and average body fat percentage, in order to determine if there were any easily observable dependencies.ResultsNo convincing correlations between threshold parameters and gross physiologic measurements were observed.ConclusionThese results suggest it is unlikely that a simple physiologic measurement of subject anatomy can be used to guide the operation of MRI scanners in a subject‐specific manner in order to increase gradient system performance while avoiding PNS. J. Magn. Reson. Imaging 2003;17:716–721. © 2003 Wiley‐Liss, Inc.
Kidneys in hypertensive rats show reduced response to nitric oxide synthase inhibition as evaluated by BOLD MRI
Authors: Li Luping , Storey Pippa , Kim David , Li Wei , Prasad Pottumarthi 
Published: May 2003

AbstractPurposeTo examine whether the noninvasive technique of blood oxygenation level dependent magnetic resonance imaging (BOLD MRI) can detect changes in renal medullary oxygenation following administration of a nitric oxide (NO) synthase inhibitor, NG‐nitro‐L‐arginine methyl ester (L‐NAME). Hypertension is associated with endothelial dysfunction and is characterized by a lack of response to endothelial‐dependent vasoactive substances, including nitric oxide synthase inhibitors. We hypothesized that the magnitude of the change would be reduced in the kidneys of hypertensive subjects relative to normal controls.Materials and MethodsTo test this hypothesis, data were obtained in spontaneously hypertensive rats (SHR, n = 6). Wistar‐Kyoto rats (WKY, n = 7) were used as normotensive controls.ResultsAs expected, WKY rats showed a significant response to L‐NAME (R2* increasing from 23.6±1.5 Hz to 32.5±2.2 Hz, P < 0.05), while SHR exhibited a minimal change in medullary oxygenation (R2* measuring 31.9±2.8 Hz pre‐ and 35.5±2.2 Hz post‐L‐NAME). The baseline R2* in SHR is found to be comparable to post‐L‐NAME values in WKY rats, suggesting a basal deficiency of nitric oxide in SHR.ConclusionBased on the differential effect of NO synthase inhibition on medullary oxygenation, BOLD MRI can distinguish hypertensive from normal kidney. Our results are consistent with previously reported observations using invasive methods. J. Magn. Reson. Imaging 2003;17:671–675. © 2003 Wiley‐Liss, Inc.
Accuracy of cartilage and subchondral bone spatial thickness distribution from MRI
Authors: McGibbon Chris A. , Bencardino Jenny , Yeh Eren D. , Palmer William E. 
Published: May 2003

AbstractPurposeTo assess three‐dimensional measurement accuracy of articular cartilage (AC) and subchondral bone (SB) thickness from MRI.Materials and MethodsA computer program was used to calculate AC and SB thickness from MRI (three‐dimensional spoiled gradient echo (SPGR), .31‐mm resolution, 1‐mm slice thickness) of six adult femoral heads. Specimens were imaged in five anatomical planes ranging between +30° to −30° from neutral and cut into 2‐mm thick sections along the five anatomical planes. Faxitron x‐ray was used to produce microradiographic (.05‐mm resolution) images of the sections.ResultsIn‐plane measurement accuracy was .165 ± .108 mm for AC thickness and .387 ± .174 mm for SB thickness. Taking into account chemical‐shift misregistration in SB thickness, accuracy of measurements improved to .213 ± 128 mm. Out‐of‐plane (three‐dimensional) thickness accuracy of the model, assessed by numerical simulation, was .015 mm. However, three‐dimensional thickness errors in specimens were .319 ± .256 mm for AC and .253 ± .183 mm for SB thickness.ConclusionErrors in three‐dimensional AC thickness were attributed to volume‐averaging effects caused by oblique intersection of the image plane with the joint surface. Errors in three‐dimensional SB thickness were attributed to chemical‐shift artifact. We conclude that accuracy of AC thickness is within clinically acceptable standards but that more sophisticated pulse sequences are needed to improve the measurement of SB thickness. J. Magn. Reson. Imaging 2003;17:703–715. © 2003 Wiley‐Liss, Inc.
Evaluation of sodium T1 relaxation times in human heart
Authors: Pabst Thomas , Sandstede Joern , Beer Meinrad , Kenn Werner , Neubauer Stefan , Hahn Dietbert 
Published: May 2003

AbstractPurposeTo evaluate the sodium longitudinal relaxation (T1) characteristics for myocardium and blood in humans.Materials and MethodsEleven healthy volunteers were examined by using a 23Na heart surface coil at a 1.5 T clinical scanner equipped with a broadband spectroscopy option. 23Na MR measurements were performed by using a three‐dimensional spoiled gradient echo sequence (in‐plane resolution, 3.5 mm × 7 mm; slice thickness, 24 mm; TE, 3.1 msec; bandwidth, 65 Hz/pixel; TR, 21 to 150 msec).ResultsLongitudinal T1 relaxation time components were 31.6±7.0 msec and 31.1±7.5 msec for myocardium and blood, respectively.Conclusion23Na T1 relaxation times of myocardium and blood can be determined in humans. The results are in agreement with values obtained from animal studies. J. Magn. Reson. Imaging 2003;17:726–729. © 2003 Wiley‐Liss, Inc.
Regional dynamics of the fMRI‐BOLD signal response to hypoxia‐hypercapnia in the rat brain
Authors: Kannurpatti Sridhar S. , Biswal Bharat B. , Hudetz A.G. 
Published: May 2003

AbstractPurposeTo examine the regional blood oxygenation level‐dependent (BOLD) signal response to rapid changes in arterial oxygen tension.Materials and MethodsFunctional MR imaging (fMRI) was carried out in five male Sprague‐Dawley rats anesthetized with Sodium Pentobarbital. Rats were subjected to different durations of apnea as a rapid, graded, and reversible hypoxic‐hypercapnic stimulus. Dynamics of the BOLD signal response were studied on a pixel‐by‐pixel basis in the cerebral cortex, hippocampus, third ventricle, and thalamus in the rat brain.ResultsApnea induced a BOLD signal drop in all the brain regions studied, the magnitude of which increased with longer durations of the stimulus. The signal recovered to preapnic baseline levels after resumption of normal ventilation. Regional variation in the BOLD signal dynamics was observed with the magnitude of the BOLD signal change in the hippocampus being the least, followed by a relatively larger change in the thalamus, cerebral cortex, and third ventricle. The time (t0) for the signal change after the onset of the stimulus was estimated for every pixel. Time delay maps generated show the highest onset time values in the hippocampus followed by the thalamus, cerebral cortex, and third ventricle.ConclusionThe regional dynamics of the BOLD signal in the brain in response to apnea may vary depending on the rate of oxygen metabolism in addition to cerebral blood flow (CBF). J. Magn. Reson. Imaging 2003;17:641–647. © 2003 Wiley‐Liss, Inc.
Functional evaluation of normothermic ischemia and reperfusion injury in dog kidney by combining MR diffusion‐weighted imaging and Gd‐DTPA enhanced first‐pass perfusion
Authors: Liu Ai‐Shi , Xie Jing‐Xia 
Published: May 2003

AbstractPurposeTo evaluate functional alterations of renal ischemia and reperfusion injury using MR diffusion‐weighted imaging and dynamic perfusion imaging.Materials and MethodsTwelve dogs were randomly divided into four groups. Animal renal ischemia was respectively induced for 30 (group 1), 60 (group 2), 90 (group 3), and 120 (group 4) minutes by left renal artery ligation under anesthesia. Using a 1.5 T MR system, true‐FISP, TSE, EPI, and DWI sequences were acquired in five different periods; specifically, pre‐ischemia, onset‐ischemia, late ischemia, onset‐reperfusion, and post‐reperfusion. Moreover, a turbo‐FLASH sequence (TR/TE/TI/FA = 5.8/3.2/400 msec/10°) with a temporal resolution of 1.16 seconds was acquired. Signal intensity (SI) was measured in the cortex, outer medulla, and inner medulla of kidney. Apparent diffusion coefficient (ADC) values were calculated, and SI was plotted as a function of time.ResultsIn all animals, significant SI changes of the left kidney on T2/T2*WI were detected following ischemia‐reperfusion insult compared to corresponding values of the right kidney. Following ligation, the ADC values decreased in all layers of the left kidney. Immediately after the release of ligation, ADC values in both outer and inner medulla of the left kidney remained lower than those of the right kidney in those animals which were induced with renal ischemia for 60, 90, and 120 minutes. In all groups, a uniphasic enhancement pattern was observed in the outer and inner medulla of the left kidney, accompanied by a decrease of the area under the curve.ConclusionOur results suggest that MR diffusion‐weighted imaging and dynamic perfusion imaging are useful in identifying renal dysfunction following normothermic ischemia and reperfusion injury. J. Magn. Reson. Imaging 2003;17:683–693. © 2003 Wiley‐Liss, Inc.
Contrast‐enhanced MR angiography of the run‐off vasculature: Intraindividual comparison of gadobenate dimeglumine with gadopentetate dimeglumine
Authors: Knopp Michael V. , Giesel Frederik L. , von Tengg‐Kobligk Hendrik , Radeleff Jannis , Requardt Martin , Kirchin Miles A. , Hentrich Hans‐Rainer 
Published: May 2003

AbstractPurposeTo compare intraindividually gadobenate dimeglumine (Gd‐BOPTA) with gadopentetate dimeglumine (Gd‐DTPA) for multi‐station MR Angiography of the run‐off vessels.Materials and MethodsTwenty‐one randomized healthy volunteers received either Gd‐BOPTA or Gd‐DTPA as a first injection and then the other agent as a second injection after a minimum interval of 6 days. Each agent was administered at a dose of 0.1 mmol/kg bodyweight followed by a 25‐mL saline flush at a single constant flow rate of 0.8 mL/second. Images were acquired sequentially at the level of the pelvis, thigh, and calf using a fast three‐dimensional (3D) gradient echo sequence. Source, subtracted source, maximum intensity projection (MIP), and subtracted MIP image sets from each examination were evaluated quantitatively and qualitatively on a segmental basis involving nine vascular segments.ResultsSignificantly (P < 0.05) higher signal‐to‐noise and contrast‐to‐noise ratios were noted for Gd‐BOPTA compared to Gd‐DTPA, with the more pronounced differences evident in the more distal vessels. Qualitative assessmentrevealed no differences in the abdominal vasculature, a preference for Gd‐BOPTA in the pelvic vasculature, and markedly better performance for Gd‐BOPTA in the femoral and tibial vasculature. Summation of individual diagnostic quality scores for each segment revealed a significantly (P = 0.0001) better performance for Gd‐BOPTA compared to Gd‐DTPA.ConclusionGreater vascular enhancement of the run‐off vasculature is obtained after Gd‐BOPTA, particularly in the smaller more distal vessels. Enhancement differences are not merely dose dependent, but may be due to different vascular enhancement characteristics of the agents. J. Magn. Reson. Imaging 2003;17:694–702. © 2003 Wiley‐Liss, Inc.
Visualization and quantification of renal R2* changes during water diuresis
Authors: Zuo Chun S. , Rofsky Neil M. , Mahallati Houman , Yu Jeongsik , Zhang Ming , Gilbert Scott , Epstein Franklin H. 
Published: May 2003

AbstractPurposeTo refine and evaluate methods for analysis of renal blood oxygenation level dependent (BOLD) MRI data.Materials and MethodsColor R2* maps and regions‐of‐interest (ROIs) on the borderline between cortex and medulla were applied to renal BOLD MRI data of a group of 13 young female subjects.ResultsThe distribution of R2* within the kidneys was heterogeneous and the response of human kidneys to water diuresis was patchy. R2* values at the cortico‐medullary border region have a smaller variation than in wider cortical or medullary regions and are sensitive to physiological changes produced by water diuresis.ConclusionThese methods provide improved visualization of the regional distribution of R2* and its variations and more precise quantification of the changes in renal R2* produced by water diuresis. J. Magn. Reson. Imaging 2003;17:676–682. © 2003 Wiley‐Liss, Inc.
Proton spectroscopic metabolite signal relaxation times in preterm infants: A prerequisite for quantitative spectroscopy in infant brain
Authors: Kugel Harald , Roth Bernhard , Pillekamp Frank , Krüger Karsten , Schulte Oliver , von Gontard Alexander , Benz‐Bohm Gabriele 
Published: May 2003

AbstractPurposeTo determine relaxation times of metabolite signals in proton magnetic resonance (MR) spectra of immature brain, which allow a correction of relaxation that is necessary for a quantitative evaluation of spectra acquired with long TE. Proton MR spectra acquired with long TE allow a better definition of metabolites as N‐acetyl aspartate (NAA) and lactate especially in children.Materials and MethodsRelaxation times were determined in the basal ganglia of 84 prematurely born infants at a postconceptional age of 37.8 ± 2.2 (mean ± SD) weeks. Metabolite resonances were investigated using the double‐spin‐echo volume selection method (PRESS) at 1.5 T. T1 was determined from intensity ratios of signals obtained with TRs of 1884 and 6000 msec, measured at 3 TEs (25 msec, 136 msec, 272 msec). T2 was determined from signal intensity ratios obtained with TEs of 136 msec and 272 msec, measured at 2 TR. Taking only long TEs reduced baseline distortions by macromolecules and lipids. For myo‐inositol (MI), an apparent T2 for short TE was determined from the ratio of signals obtained with TE = 25 msec and 136 msec. Intensities were determined by fitting a Lorentzian to the resonance, and by integration.ResultsRelaxation times were as follows: trimethylamine‐containing compounds (Cho): T1 = 1217 msec/T2 = 273 msec; total creatine (Cr) at 3.9 ppm: 1010 msec/111 msec; Cr at 3.0 ppm: 1388 msec/224 msec; NAA: 1171 msec/499 msec; Lac: 1820 msec/1022 msec; MI: 1336 msec/173 msec; apparent T2 at short TE: 68 msec.ConclusionT1 and T2 in the basal ganglia of premature infants do not differ much from previously published data from basal ganglia of older children and adults. T2 of Cho was lower than previous values. T2 of Cr at 3.9 ppm and Lac have been measured under different conditions before, and present values differ from these data. J. Magn. Reson. Imaging 2003;17:634–640. © 2003 Wiley‐Liss, Inc.
Double inversion black‐blood fast spin‐echo imaging of the human heart: A comparison between 1.5T and 3.0T
Authors: Greenman Robert L. , Shirosky John E. , Mulkern Robert V. , Rofsky Neil M. 
Published: May 2003

AbstractPurposeTo evaluate the effectiveness of blood suppression and the quality of black‐blood cardiac images acquired at 3.0 Tesla using a double‐inversion recovery fast spin‐echo sequence by comparing data acquired at 3.0T to data acquired at 1.5T.Materials and MethodsBlack‐blood T2‐weighted fast spin‐echo images of the heart were acquired from five normal volunteers at 1.5T and five normal volunteers at 3.0T. Region‐of‐interest signal intensity measurements were performed at several locations in the suppressed blood regions of the left and right ventricles and around the left ventricle walls to assess the effectiveness and uniformity of the blood suppression, the myocardial signal‐to‐noise ratio (SNR), and the signal uniformity at both field strengths. B1 field maps were produced in phantoms and in subjects at both field strengths.ResultsBlood suppression performance is equivalent at 1.5T and 3.0T. The improvement in SNR at 3.0T compared with 1.5T is less than has been predicted in previous studies. The signal uniformity is significantly poorer at 3.0T than at 1.5T due to dielectric effects and shorter radio frequency wavelengths (P < 0.005).ConclusionSpin‐echo and spin‐echo echo‐train sequences that perform well at 1.5T will produce large signal variations in the chest cavity at 3.0T without modifications. B1 insensitive methods must be explored and implemented for spin‐echo sequences to fully realize the advantages of using these sequences for high‐field MRI. J. Magn. Reson. Imaging 2003;17:648–655. © 2003 Wiley‐Liss, Inc.
Improvement of image quality of non‐invasive coronary artery imaging with magnetic resonance by the use of the intravascular contrast agent Clariscan™ (NC100150 injection) in patients with coronary artery disease
Authors: Klein Christoph , Schalla Simon , Schnackenburg Bernhard , Bornstedt Axel , Hoffmann Volker , Fleck Eckart , Nagel Eike 
Published: May 2003

AbstractPurposeTo assess the feasibility of Clariscan™, an intravascular contrast agent, for free breathing, navigator assisted, high resolution, three‐dimensional‐magnetic resonance coronary angiography (MRCA) in patients, as extracellular contrast agents are unfavorable for the improvement of image quality.Materials and MethodsMRCA was performed in 10 patients with known coronary artery disease (CAD) with (1–5 mg Fe/kg body weight) and without contrast agent.ResultsCompared to unenhanced images, Clariscan™ did not improve signal‐to‐noise (SNR) or contrast‐to‐noise ratios (CNR) compared to fat or myocardium in the proximal parts of the coronary arteries. However, when analyzing the peripheral parts (>4 cm from origin), CNRfat and CNRmyo improved up to a factor of 1.81 and 5.85, respectively, at a dose of 3 mg Fe/kg body weight, while SNR did not reach statistical significance. The visible length of the coronary arteries was improved from 49 ± 18 mm to 73 ± 33 mm. The proximal diameter was reduced from 3.6 ± 0.8mm to 3.2 ± 0.8 mm, representing more closely the diameter of 3.1 ± 0.7 mm measured by quantitative coronary angiography. Of 11 significant stenoses (>50%), eight were identified in the enhanced compared to six in the unenhanced images.ConclusionThe use of Clariscan™ at a dose of 2–3 mg Fe/kg body weight improves image quality of three‐dimensional‐MRCA, especially in the peripheral segments, and, thus, the diagnostic accuracy for the detection of CAD. J. Magn. Reson. Imaging 2003;17:656–662. © 2003 Wiley‐Liss, Inc.
Difference in prognosis between patients infected with hepatitis B virus with genotype B and those with genotype C in the Okinawa Islands: A prospective study
Authors: Nakayoshi Tomokuni , Maeshiro Tatsuji , Nakayoshi Tomofumi , Nakasone Hiroki , Sakugawa Hiroshi , Kinjo Fukunori , Orito Etsuro , Mizokami Masashi 
Published: May 2003

AbstractThe factors contributing to the prognosis of hepatitis B virus (HBV)‐ related chronic liver disease were assessed prospectively in 72 patients with chronic hepatitis B confirmed clinically and pathologically. A comparative study was undertaken between patients infected with genotype B and those with genotype C. During the follow‐up period, 13 (81.3%) of 16 patients with genotype B who were initially hepatitis B e antigen (HBeAg) positive became HBeAg negative and 14 (51.9%) of 27 with genotype C became HBeAg negative. HBeAg had been cleared in 8 (61.5%) of 13 patients with genotype B within the first 2 years of the follow‐up, but in only one (7.1%) of 14 with genotype C (P < 0.05). Four (11.4%) of 35 patients with genotype B had progressed to cirrhosis, whereas, 12 (32.4%) of 37 patients with genotype C progressed to cirrhosis, including two patients with hepatocellular carcinoma. Multivariate analysis showed that difference in HBV genotype influenced significantly either the clearance of HBeAg or the development of cirrhosis. In conclusion, HBeAg was cleared from sera more frequently and earlier in patients with genotype B compared with those with genotype C, and development of cirrhosis occurred less frequently in patients with genotype B compared with those with genotype C. Thus, HBV genotypes may influence the prognosis of HBV‐related chronic liver disease. J. Med. Virol. 70:350–354, 2003. © 2003 Wiley‐Liss, Inc.