bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of magnetic particles for sensitizing MR images to blood flow
Authors: Hardy Peter A. , Bronskill Michael J. , Belanger Marie‐Jose , Henkelman R. Mark 
Published: March 2007

AbstractMagnetic resonance (MR) images made with the IVIM (intravoxel incoherent motion) technique for demonstrating tissue microcirculation are limited in sensitivity because of the small volume of blood involved. This limitation may be overcome by incorporating magnetic particles into the flow. The magnetic perturbation caused by the particles extends beyond the walls of the capillary and affects a much larger volume than that of the flowing material. Imaging experiments conducted with an artificial capillary system for renal dialysis, containing large magnetic particles, showed that signal intensity decreased with increasing flow rate through the dialysis bundle and with increasing particle concentration. Predictions of the effect based on a theoretical model of spin dephasing in the field of a magnetic dipole agreed with the experimental data. The results hold promise for development of the technique in vivo.
Muscle edema in musculoskeletal tumors: MR imaging characteristics and clinical significance
Authors: Hanna Soheil L. , Fletcher Barry D. , Parham David M. , Bugg Michael F. 
Published: March 2007

AbstractTo determine the frequency and clinical significance of tumor‐associated muscle edema, magnetic resonance (MR) imaging findings in 46 consecutive patients with benign or malignant musculoskeletal lesions were reviewed. Increased muscle signal intensity on T2‐weighted, STIR (short‐inversion‐time inversion‐recovery), and gadopentetate dimeglumine‐enhanced TI‐weighted images was present in 41 cases, with the clearest delineation of tumor margins seen on T2‐weighted images. Typical peri/paratu‐moral edema (PTE) was present in equal proportions of malignant (25 of 37) and benign lesions (six of nine). Massive edema involving the entirety of at least one contiguous muscle‐to the authors' knowledge, a previously undescribed finding‐was identified on MR images of eight malignant and two benign lesions (22% of both groups). All cases of massive edema had a substantial soft‐tissue component and involved muscles disrupted by tumor at the point of attachment to bone. Malignant tumors associated with massive edema were larger than those with typical or no PTE, showed a poorer response to initial chemotherapy, and had a higher frequency of metastases at diagnosis. Thus, the presence of massive muscle edema appears to be an ominous clinical finding in patients with malignant musculoskeletal lesions.
Phase‐offset multiplanar (POMP) volume imaging: A new technique
Authors: Glover Gary H. 
Published: March 2007

AbstractPhase‐offset multiplanar (POMP) imaging is a technique that excites several sections simultaneously for improved imaging efficiency. The centers of the reconstructed images from each of the POMP sections are offset from each other in the phase‐encoding direction by means of view‐dependent phase modulation of the radio‐frequency (RF) excitation pulses and are placed adjacent to each other in the reconstruction. With a suitable reconstruction matrix size, the images can be made nonoverlapping and stored separately. At constant imaging time, signal‐to‐noise ratio (S/N), and resolution, POMP imaging produces a factor In: Book of abstracts: Society of Magnetic Resonance in Medicine In: Book of abstracts: Society of Magnetic Resonance in Medicine Np more sections than a conventinal sequence but with a reduced field of view. Alternatively, imaging time may be invreased by the factor Np to retain the same field of view but with the expected S/N advantage. The average RF power deposited by the 90° composite RF pulse is greater by the factor Np, but the power for the 180° pulse is unchanged. The POMP method is discussed and compared with three‐dimensional and Hadamard techniques.
Clinical comparison of three‐dimensional MP‐RAGE and FLASH techniques for MR imaging of the head
Authors: Runge Val M. , Kirsch John E. , Thomas Gregory S. , Mugler John P. 
Published: March 2007

AbstractThree‐dimensional (3D) MP‐RAGE (magnetization‐prepared rapid gradient‐echo) imaging was evaluated as a high‐resolution 3D T1‐weighted brain imaging technique for patients with suspected neurologic disease. Fourteen patients were studied. In five, 3D MP‐RAGE images were compared with 3D FLASH (fast low‐angle shot) images. Signal difference‐to‐noise ratios and T1 contrast were not statistically different for 3D MP‐RAGE images as opposed to 3D FLASH images. Advantages intrinsic to the application of 3D MP‐RAGE sequences include decreased imaging time and decreased motion artifact. With this technique, it is possible to perform a relatively motion‐insensitive, T1‐weighted screening brain study with voxel resolution of 1.0 × 1.4 × 2.0 mm or smaller, in an imaging time of 5.9 minutes or less‐permitting offline (poststudy) reconstruction of high‐resolution images in any desired plane.
Prostate and seminal vesicles after irradiation: MR appearance
Authors: Chan Teresa W. , Kressel Herbert Y. 
Published: March 2007

AbstractFamiliarity with the morphologic changes in the prostate and seminal vesicles (SV) after pelvic irradiation is important to the correct interpretation of follow‐up magnetic resonance (MR) studies. A retrospective study of 38 patients with prostatic or other pelvic tumors treated with radiation showed that 31.6% had a normal prostatic zonal pattern (peripheral zone hyper‐intense to central gland) on T2‐weighted images, and 7.9% showed reversal of the zonal pattern; among the rest, the entire gland was diffusely isointense to fat in 42.1%, hypointense to fat in 10.5%, and hyperintense to fat in 7.9%. Sixty‐three percent of the SV had a normal appearance, 21% had fewer tubules but normal signal intensity (SI), 8% had diffuse loss of SI (hypointense to fat), and 8% were hypointense to muscle. Quantitative measurements of SI of the prostate and SV demonstrated a statistically significant lower mean value for the irradiated patients relative to 10 control patients. A decrease in the size of both the prostate and SV was observed in 33% of patients with baseline studies. Use of additional treatment modalities in patients with prostatic carcinoma appeared to correlate with increased likelihood of developing abnormal changes. The authors conclude that in the irradiated patient, the prostate and SV can develop several patterns of SI abnormalities; in particular, diffuse low SI in the prostate and SV should establish radiation fibrosis as an important differential diagnosis to consider.
Diagnostic value of gadopentetate dimeglumine for 1.5‐T MR imaging of musculoskeletal masses: Comparison with unenhanced T1‐and T2‐weighted imaging
Authors: Rosenthal Richard E. , Wozney Paul 
Published: March 2007

AbstractThree magnetic resonance (MR) imaging techniques (T1‐weighted, T2‐weighted, and T1‐weighted gadopentetate dimeglumine—enhanced) were compared in 32 consecutive MR imaging studies of 26 patients with suspected musculoskeletal masses. T2‐weighted images were superior to T1‐weighted enhanced images with respect to detection and definition of lesions in 12% of cases (n = 4) and were equal in 88% of cases (n = 28). T2‐weighted images were also superior to T1‐weighted images in 38% of cases (n = 12). In no cases were T1‐weighted enhanced images superior to T2‐weighted images. In two cases, T1‐weighted images were superior to both T1‐weighted enhanced and T2‐weighted images. The authors conclude that gadopentetate dimeglumine did not provide much value in lesion detection above that obtained with T2‐weighted images. They also conclude that T1‐weighted images were occasionally superior to T1‐weighted enhanced images and T2‐weighted images because of loss of definition between fat and lesion on the latter.
Rapid three‐dimensional T1‐weighted MR imaging with the MP‐RAGE sequence
Authors: Mugler John P. , Brookeman James R. 
Published: March 2007

AbstractThe authors investigated the application of three‐dimensional (3D) magnetization‐prepared rapid gradient‐echo (MP‐RAGE) imaging to the acquisition of small (32 × 128 × 256) T1‐weighted 3D data sets with imaging times of approximately 1 minute. A theoretical model was used to study the contrast behavior of brain tissue. On the basis of these theoretical results, 3D MP‐RAGE sequences were implemented on a 1.5‐T whole‐body imager. Thirty‐two‐section 3D data sets demonstrating good signal‐to‐noise ratios and resolution and strong T1‐weighted contrast were obtained in 1 minute. Compared with standard short TR/TE spin‐echo sequences with the same imaging times and comparable sequence parameters, the 3D MP‐RAGE sequence delivered increases of more than 50% in the white matter/gray matter signal difference‐to‐noise and white matter signal‐to‐noise ratios, and provided almost twice as many sections. These sequences may find a clinical role in 3D scout imaging and screening and in patients with claustrophobia or trauma.
T2‐weighted thin‐section imaging with the multislab three‐dimensional RARE technique
Authors: Oshio Koichi , Jolesz Ferenc A. , Melki Philippe S. , Mulkern Robert V. 
Published: March 2007

AbstractA novel three‐dimensional (3D) RARE (rapid acquisition with relaxation enhancement) sequence was implemented on a clinical imager. In this technique, multiple slabs are excited in the same way as in the multisection spin‐echo sequence, and each slab is further phase encoded into eight sections along the section‐slab direction. With a 16‐echo RARE sequence, 128 excitations cover the 256 × 256 × 8 3D k space. With a TR of 2.500 msec, 10 slabs can be excited sequentially at each TR, yielding 80 sections in 5 minutes. Slabs were overlapped to give contiguous sections after discarding of the aliased sections at slab edges. This relatively fast sequence makes contiguous thin‐section T2‐weighted imaging possible, an impractical achievement with the much longer spin‐echo method. Compared with 3D Fourier transform gradient‐echo imaging, the sensitivity of 3D RARE sequences to magnetic susceptibility is reduced. The clinical potential of T2‐weighted 3D imaging is illustrated with high‐resolution brain, spine, and temporomandibular joint images.
In vivo F‐19 chemical shift imaging with FTPA and antibody‐coupled FMIQ
Authors: Mishima Hideyuki , Kobayashi Tetsurou , Shimizu Masahiro , Tamaki Yasuhiro , Baba Masashi , Shimano Takashi , Itoh Soichi , Yamazaki Masaru , Iriguchi Norio , Takahashi Mutsumasa , Mori Takesada 
Published: March 2007

AbstractA mixture of perfluoromethyldecahydroisoquinoline (FMIQ) emulsion coupled with anti‐CEA (carcinoembryonic antigen) antibody and perfluorotripropylamine (FTPA) was injected into a nude mouse inoculated with human colon carcinoma LS174T. Three days after the injection, in vivo fluorine‐19 chemical shift images of the spectral signals of the two perfluorocarbons (PFCs) were obtained simultaneously. The signal intensities and distributions of FMIQ and FTPA were similar in the liver and spleen but different in the tumor. FMIQ was detected in almost the entire tumor, with scattered areas of high uptake. FTPA, however, was detected only in the center of the tumor. The results suggest that F‐19 chemical shift imaging of two PFCs, one coupled to antibody and the other not, has potential application in tumor diagnosis.
Extrusion of Eye socket magnetic implant after MR imaging: Potential hazard to patient with eye prosthesis
Authors: Yuh William T. C. , Hanigan Michael T. , Nerad Jeffrey A. , Ehrhardt James C. , Carter Keith D. , Kardon Randy H. , Shellock Frank G. 
Published: March 2007

AbstractMetallic implants or prostheses can be potentially hazardous during magnetic resonance (MR) imaging because of movement or dislodgment of the foreign object. Magnetic eye implants have been reported to exhibit strong movement when placed in water and exposed to a field of 1.5 T. The authors report a case of orbital implant extrusion possibly caused by the movement of a magnetic orbital implant during MR imaging at 0.5 T.
Color flow‐encoded MR imaging
Authors: Tasciyan Talin A. , Mitchell Donald G. , Spritzer Charles E. 
Published: March 2007

AbstractMagnetic resonance phase images can enable identification of any type of motion, including the velocity and direction of flow, and thus provide valuable supplements to magnitude images, which depict stationary tissue most effectively. A method is described for the simultaneous display of phase and magnitude by color encoding the phase data and superimposing it on the magnitude image to facilitate clinical interpretation. Colorencoded data not only depict the location and direction of flow along specific axes but can also provide relative velocity information through shades of color. Implementation of the technique is described, and the factors to be considered during interpretation of color flow‐encoded images are discussed.
Boron‐11 imaging with a three‐dimensional reconstruction method
Authors: Glover Gary H. , Pauly John M. , Bradshaw Kenneth M. 
Published: March 2007

AbstractA three‐dimensional projection reconstruction technique is described for imaging boron‐11 distributions, with potential application to boron neutron capture therapy. The method samples a spherical volume of k space uniformly to obtain a 32 × 32 × 32 matrix with voxel size of 0.42 cm3. A signal‐to‐noise ratio (S/N) of 3 was obtained in 8.5 minutes in a phantom containing 75 ug/mL of boron in borocaptate sodium (BSH). Images were obtained in a dog after cessation of an intravenous infusion of BSH and again 30 minutes later, with a maximum boron S/N of about 12. Boron levels in the brain dropped about 6%‐8% and were more diffusely distributed on the images obtained 30 minutes after BSH infusion.
MR‐guided aspiration cytology in the head and neck at high field strength
Authors: Hathout Gasser , Lufkin Robert B. , Jabour Bradley , Andrews James , Castro Dan 
Published: March 2007

AbstractPublished reports of magnetic resonance (MR)‐guided needle biopsy have involved low‐and mid‐field‐strength systems because of the concern of needle artifact and risk of increased needle torque at higher field strengths. To the authors' knowledge, this is the first report of a high‐field‐strength (1.5‐T) system used to guide aspiration cytology in the head and neck in a patient. The procedure was successfully accomplished without additional needle torque or substantial increase in image artifact relative to lower‐field‐strength imaging.
Cardiac ejection fraction: Phantom study comparing cine MR imaging, radionuclide blood pool imaging, and ventriculography
Authors: Debatin Jörg F. , Nadel Scott N. , Paolini John F. , Sostman H. Dirk , Edward Coleman R. , Evans Avery J. , Beam Craig , Spritzer Charles E. , Bashore Thomas M. 
Published: March 2007

AbstractThe accuracy and reproducibility of cardiac ejection fraction (EF) measurements based on cine magnetic resonance (MR) imaging, radionuclide multigated acquisition (MUGA) blood pool imaging, and angiographic ventriculography were evaluated by comparing them with a volumetrically determined standard. A biventricular, compliant, fluid‐filled heart phantom was developed to mimic normal cardiac anatomy and physiology. Ventricular EFs were measured with cine MR imaging by summation of nine contiguous 10‐mm‐thick sections in short and long axis, with single‐plane ventriculography, and with MUGA. Three measurements were performed with each modality for each of three EFs. Ventriculography was least accurate, with average relative errors ranging from 7.9% for the largest EF to 60.1% for the smallest. Cine MR was most accurate, with average relative errors ranging from 4.4% to 8.5%. MUGA EF measurements showed good correlation, with average relative errors ranging from 7.1% to 22.4%. Comparison of the error variances for the three modalities with the F test revealed that MR and MUGA EF measurements were significantly more accurate than those based on ventriculography (P <.01). No significant difference was demonstrated between the accuracy of short‐ and long‐axis cine MR acquisitions.
Tracking motion with tagged rapid gradient‐echo magnetization‐prepared MR imaging
Authors: Niitsu Mamoru , Campeau Norbert G. , Holsinger‐Bampton Anna E. , Riederer Stephen J. , Ehman Richard L. 
Published: March 2007

AbstractA technique for rapid assessment of tissue motion was developed by combining spatially selective radio‐frequency tagging pulses with centric phase‐encoding view ordering in a T1‐weighted, magnetization‐prepared gradient‐echo acquisition sequence. This sequence allowed labeling and tracking of tissue motion with single‐image acquisition times of less than 3 seconds. Multiple tagged bands 3 mm thick were superimposed orthogonal to the imaging plane. Motion in the interval between tagging and the start of image acquisition could then be precisely determined. The technique was evaluated with phantom studies and then applied to human volunteers for assessment of skeletal muscle motion, phonation, and pelvic floor motion.
MR imaging and metallic implants for anterior cruciate ligament reconstruction: Assessment of ferromagnetism and artifact
Authors: Shellock Frank G. , Mink Jerrold H. , Curtin Sharon , Friedman Marc J. 
Published: March 2007

AbstractMagnetic resonance (MR) imaging is contraindicated for patients with certain ferromagnetic implants, primarily because of potential risks related to movement or dislodgment of the devices. An additional problem with metallic implants is the potential image distortion that may affect the interpretation of the MR study. Since MR imaging is frequently useful for the evaluation of postoperative anterior cruciate ligament (ACL) reconstruction, the ferromagnetic qualities and artifacts associated with MR imaging were determined for five metallic orthopedic implants commonly used for this surgery. Only the Perfix interference screw displayed a substantial deflection force and caused extensive signal loss. Images of the knee of one patient with two Perfix screws in place were not interpretable because of the image distortion caused by these implants. Therefore, alternative nonferromagnetic implants should be considered for reconstruction of the ACL.
An overview of digital spectrometers for MR imaging
Authors: Holland G. Neil , Macfall James R. ,   Instrumentation Subcommittee of the SMRI Basic Science Council
Published: March 2007

AbstractMost magnetic resonance (MR) imaging systems were originally designed with analog spectrometers, since that was the “state of the art” in the late 1970s, when they were developed. Advances in technology have allowed the design of radio‐frequency electronics with a much larger percentage of digital components while the cost of such components has decreased. This has given manufacturers the incentive to develop new spectrometers that incorporate these electronics for cost reduction and potentially better performance. Upgrades and new models of MR units have become available with these so‐called “digital spectrometers.” Because of the interest in the new systems, the Instrumentation Subcommittee of the Basic Science Council of the Society for Magnetic Resonance Imaging has produced this report to review the basic features of analog and digital spectrometers to help the MR imaging community better understand the similarities and differences of these systems. Some details of actual commercial implementations were left out to focus on the basic features. Regardless, the authors hope they have provided a readable introduction to this important topic.
Lipid‐suppressed single‐and multisection proton spectroscopic imaging of the human brain
Authors: Spielman Daniel M. , Pauly John M. , Macovski Albert , Glover Gary H. , Enzmann Dieter R. 
Published: March 2007

AbstractSpectroscopic images of the brain have great potential in disease diagnosis and treatment monitoring. Unfortunately, interfering lipid signals from subcutaneous fat and poor water suppression due to magnetic field inhomogeneities can make such images difficult to obtain. A pulse sequence that uses inversion recovery for lipid suppression and a spectral‐spatial refocusing pulse for water suppression is introduced. In contrast to methods that eliminate fat signal by restricting the excited volume to lie completely within the brain, inversion‐recovery techniques allow imaging of an entire section without such restrictions. In addition, the spectral‐spatial pulse was designed to provide water suppression insensitive to a reasonable range of B0 and B1 inhomogeneities. Several data processing algorithms have also been developed and used in conjunction with the new pulse sequence to produce metabolite maps covering large volumes of the human brain. Images from single‐ and multisection studies demonstrate the performance of these techniques.
Proton MR spectroscopy of gadolinium‐enhanced multiple sclerosis plaques
Authors: Narayana Ponnada A. , Wolinsky Jerry S. , Jackson Edward F. , McCarthy Micheline 
Published: March 2007

AbstractMagnetic resonance (MR) imaging and proton MR spectroscopy were performed in 14 patients with clinically definite multiple sclerosis (MS). Prominent resonances in the 0.5‐2.0‐ppm region were seen in the spectra of six of nine gadopentetate dimeglumine‐enhanced plaques in seven patients. These resonances were presumed to originate in lipids and other myelin breakdown products. Similar resonances were detected in only seven of 21 unenhancing plaques. The more frequent presence of such signals in the gadolinium‐enhanced regions indicates that myelin breakdown is often associated with the inflammation that occurs in early stages of MS plaque evolution. It remains uncertain, however, whether active inflammation as indicated by gadolinium enhancement is a necessary precursor of myelin breakdown as detected at MR spectroscopy. Quantitative spectral analysis did not indicate statistically significant differences in N‐acetyl aspartate and choline levels relative to creatine plus phosphocreatine between healthy volunteers and MS patients.
Ultrafast MR imaging of water mobility: Animal models of altered cerebral perfusion
Authors: McKinstry Robert C. , Weiskoff Robert M. , Belliveau John W. , Vevea James M. , Moore John B. , Kwong Kenneth W. , Halpern Elkan F. , Rosen Bruce R. 
Published: March 2007

Abstract“Single shot” magnetic resonance (MR) diffusion imaging was used to study the details of signal decay curves in experimental perturbations of cerebral perfusion induced by hypercapnia or death. Despite large perfusion increases observed with dynamic susceptibility‐contrast MR imaging, no correlation with these changes was seen in either the diffusion coefficient or any other intravoxel incoherent motion (IVIM) model parameters in dog gray matter as arterial carbon dioxide pressure increased. Non‐monoexponential signal decay in cat gray matter was seen both before and after death. In addition, cat gray matter demonstrated a steady decrease in the diffusion coefficient after death. These data are strong evidence that the fast component of the non‐monoexponential diffusion‐related signal decay is not due solely to perfusion. The authors believe that a second compartment of nonex‐changing spins, most likely cerebrospinal fluid, accounts for the non‐monoexponential decay.