bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and theoretical studies of vessel contrast‐to‐noise ratio in intracranial time‐of‐flight MR angiography
Authors: Du Yiping P. , Parker Dennis L. , Davis Wayne L. , Cao Guang , Buswell Henry R. , Goodrich K. Craig
Published: March 2007

CNR studies were performed for human intracranial vessels in 3D MRA data sets. The CNR dependency of different imaging parameters, such as flip angle, field of view, echo time, repetition time, and echo readout symmetry, was studied for vessels in the region of the circle of Willis. A theoretical model was developed for MR vascular imaging based on the Bloch equations and Fourier imaging theory. This model predicts the MR image intensity of vessels from basic subject parameters, such as the relaxation times of blood and stationary tissue, vessel dimension, and flow velocity, and the parameters of the imaging technique, such as flip angle, voxel volume, repetition time, and echo time. For most experiments, the model was found to fit the experimental results well. The validity of this model allows the optimization of imaging parameters to maximize vessel CNR in MR angiography.
Surface coil phased arrays for high‐resolution imaging of the carotid arteries
Authors: Hayes Cecil E. , Mathis C. Mark , Yuan Chun
Published: March 2007

An MR phased‐array coil assembly was developed to obtain high‐resolution images of atherosclerotic plaques in the carotid artery. Images of volunteers and patients obtained by using alternative coil designs provided a subjective assessment of the coils' performance, field of view, ease of use, and susceptibility to motion artifacts. A quantitative measurement performed on a phantom indicated that a two‐coil phased‐array design should produce a 37% better signal‐to‐noise ratio at the carotids than would a conventional single 3‐inch surface coil.
Improved reproducibility in measuring LV volumes and mass using multicoil breath‐hold cine MR imaging
Authors: Sakuma Hajime , Globits Sebastian , Bourne Michael W. , Shimakawa Ann , Foo Thomas K. , Higgins Charles B.
Published: March 2007

There is a generally recognized need for improvement in quality of fast cardiac MR images. Consequently, breath‐hold cine MR images were obtained with multiple surface coils connected to phased array receivers, and C/N, intra‐observer and inter‐observer variabilities for LV volumes and mass were evaluated. Two sets of short‐axis images of the LV, one with multiple surface coils and another with a body coil, were acquired in eight subjects with a fast cine MR sequence using k‐space segmentation (TR/TE=7/2.2 msec, temporal resolution=56 msec). C/N with multicoil imaging was 32.2 ± 7.6 (mean ± SD), significantly higher than that with a body coil (11.0 ± 3.3, P < .01). The mean percentage differences in intra‐observer and inter‐observer measurements with multicoil imaging were significantly better than those with a body coil. In conclusion, multicoil imaging provides significant gain in C/N on breath‐hold cine MRI of the heart. In addition, intra‐observer and inter‐observer reproducibilities are improved with multicoil imaging.
Optimizing fast spin echo acquisitions for hepatic imaging in normal subjects
Authors: Spritzer Charles E. , Keogan Mary T. , DeLong David M. , Dahlke Jerry , MacFall James R.
Published: March 2007

The purpose of this study was to determine which implementations of a T2‐weighted fast spin‐echo sequence of the liver resulted in observer preference in normal subjects. Five volunteers were scanned with a series of fast spin‐echo sequences modified to allow for flow compensation, respiratory triggering (RT), ECG triggering, randomized phase encoding (RPE), breathholding, and echo train length (ETL). Images were compared with conventional 2500/40/80 msec spin‐echo images using flow compensation and spatial presaturation by two observers blinded to the specific sequence parameters. All FSE sequences were completed in less than the 12 minutes necessary to perform a conventional spin‐echo sequence. The most preferred fast spin‐echo sequence employed flow compensation, RT, and used an 8 ETL. Analysis of image preference, signal to noise, and contrast to noise showed that RT was the single most important variable in determining each image response (P < .01, P < .02, P < .01, respectively). There was some evidence that images obtained with an 8 ETL were preferred over those using a 16 ETL (P=.07). No other variables approached statistical significance although one reader preferred images with flow compensation in the frequency direction to those either not flow compensated or flow compensated in the slice direction. Respiratory triggered fast spin‐echo images combined with flow compensation in the frequency direction and using ETL=8 can provide image quality equal to conventional spin‐echo sequences with significant time savings.
Metastatic melanoma: Correlation of MRI characteristics and histopathology
Authors: Premkumar Ahalya , Marincola Francesco , Taubenberger Jeffery , Chow Catherine , Venzon David , Schwartzentruber Douglas
Published: March 2007

To correlate the findings on MRI with histopathology of metastatic melanoma, MRI was performed on 29 patients with 36 lesions, using spin‐echo and inversion recovery sequences. Histopathologic examination of lesions was performed within 4 weeks of imaging. Lesions were categorized according to cell type and were also evaluated for the presence and extent of melanin, iron, and necrosis. These data were then correlated with the signal intensities of the lesions. Enhancement of lesions after injection of intravenous gadolinium was calculated and correlated to vascularity of the tumor. Melanin was present more frequently in lesions appearing hyperintense or with mixed signal intensity (12/15) than in those appearing hypo‐ or isointense (6/21) on the T1‐weighted sequence. This trend was significant (P=.013). Also, more lesions appearing mixed, ie, having both hypo‐ and hyperintense components, contained melanin (15/23), as opposed to lesions that appeared to be only hyperintense (3/13) on the STIR sequence. There was no clear association between signal intensity and melanin content on the T2‐weighted sequence. There was no significant association between the signal intensities on the MR images and the iron content, tumor size, or tumor cell type of these lesions. There was no clear association between enhancement after gadolinium injection and vascularity, as assessed by histology. The authors concluded in this study that T1 shortening and hypointensity on the STIR sequence seen in patients with metastatic melanoma are most closely related to the melanin content of the tumor.
Pulsed magnetization transfer contrast for MR imaging with application to breast
Authors: Santyr Giles E. , Kelcz Frederick , Schneider Erika
Published: March 2007

The relative populations and transverse relaxation times of the solid‐like hydrogen pool (PB and T2B) and the magnetization transfer (MT) rates between the solid‐like and liquid‐like hydrogen pools (K) have been determined for three different agar gel concentrations (2%, 4%, and 8% by weight) as well as excised fibroglandular breast tissue specimens. PB was determined to be .003(.001), .01(.002), .02(.01), and .06(.01); T2B was determined to be 13.0(.2), 14.0(.1), 14.5(.1) and 15.2(1.3) μs; and K was determined to be 0.78(.01), 1.15(.02), 2.00(.02), and 3.55(1.5) sec−1 for the 2%, 4%, and 8% agar gels and the fibroglandular tissue, respectively. The image signal intensities of a pulsed MTC‐prepared gradient‐echo imaging technique are predicted using these MT parameters and are shown to agree well with experimental data obtained from a clinical MR imaging system. This technique is shown to suppress signal intensity of fibroglandular breast tissue by 40%–50% without exceeding SAR limits (≤ 8W/kg) and is helpful for visualizing lesions and silicone implants.
Breath‐hold MR measurements of blood flow velocity in internal mammary arteries and coronary artery bypass grafts
Authors: Sakuma Hajime , Globits Sebastian , O'sullivan Margaret , Shimakawa Ann , Bernstein Matt A. , Foo Thomas K. F. , Amidon Thomas M. , Takeda Kan , Nakagawa Tsuyoshi , Higgins Charles B.
Published: March 2007

Breath‐hold velocity‐encoded cine MR (VENC‐MR) imaging is a feasible method for measuring phasic blood flow velocity in small vessels that move during respiration. The purposes of the current study are to compare breathhold VENC‐MR measurements of flow velocities in the internal mammary arteries (IMA) with nonbreath‐hold measurements and to characterize the systolic and diastolic flow velocity curves in a cardiac cycle in native IMA and IMA grafts. Flow velocity in 30 native IMA and 8 IMA grafts were evaluated with a breath‐hold VENC‐MR sequence with K‐space segmentation and view‐sharing reconstruction(TR/TE=16/9 msec, VENC=100 cm/s). In 10 native IMA, nonbreathhold VENC‐MR images were acquired as well for comparison. Breath‐hold VENC‐MR imaging showed significantly higher systolic and diastolic peak velocities in native IMA (43.1 cm/second ± 15.0 and 10.0 cm/second ± 4.8), in comparison to those of nonbreath‐hold VENC‐MR imaging (27.6 cm/second ± 10.2 and 7.3 cm/second ± 3.9, P<.05). The diastolic/systolic peak velocity ratio in the IMA grafts (.88 ± .41) was significantly higher than that in native IMA (.24 ± .08, P<.01). Interobserver variability in the flow velocity measurement was less than 4%. Breath‐hold VENC‐MR imaging demonstrated higher peak flow velocity in the IMA than nonbreath‐hold VENC‐MR imaging. This technique is a rapid and effective method for the noninvasive assessment of blood flow velocity in IMA grafts.
Tissue characterization of intracranial tumors by magnetization transfer and spin‐lattice relaxation parameters in vivo
Authors: Kurki Timo , Lundbom Nina , Komu Markku , Kormano Martti
Published: March 2007

T1s and magnetization transfer (MT) parameters of 36 intracranial tumors were determined in vivo at 0.1 T to assess their use in tissue characterization. The mobile water relaxation times (T1w) did not differ between tumor groups, whereas the T1s, the apparent MT relaxation times (T1a), and the parameters MT contrast (MTC) differed significantly between several tumor types. The MT rates (Rwm) demonstrated the most significant differences; Rwm values could reliably separate high grade and low grade gliomas. T1ws of the tumors were commonly in the same range as that of normal gray matter, whereas other parameters differed from those of normal brain. The results indicate that MT rates are superior to other parameters in the characterization of intracranial tumors and may be also useful clinically in the grading of gliomas.
Macroscopic and microscopic assessments of disease burden by MRI in multiple sclerosis: Relationship to clinical parameters
Authors: Gasperini Claudio , Horsfield Mark A. , Thorpe John W. , Kidd Desmond , Barker Gareth J. , Tofts Paul S. , Macmanus David G. , Thompson Alan J. , Miller David H. , McDonald W. Ian
Published: March 2007

We have evaluated macroscopic white matter abnormalities (visible lesions) together with microscopic abnormalities in the normal appearing white matter (NAWM) of patients with multiple sclerosis (MS) to determine their relative contributions to the development of disability. The total visible lesion volume (TLV) was computed as a measure macroscopic changes, whereas both texture analysis and T2 were used as possible indicators of diffuse disease in the NAWM. Dual echo T2‐weighted SE images were obtained from 41 patients with definite MS: 10 primary progressive (PP), 11 secondary progressive (SP), 10 benign (BE), 10 early relapsing remitting (ERR), as well as from 10 healthy controls. Calculation of T2 and texture parameters were performed in a region of frontal NAWM of patients and controls. The TLV of each patient was measured using a semiautomated lesion detection program.

No significant differences were found between the controls and the patients for all texture parameters examined. However, NAWM T2 was longer in the patients than in the controls (P = .02). Mean TLV was highest for SP and lowest for BE and ERR patients. A significant correlation was found between TLV and EDSS (P < .01) but not between NAWM T2 or texture and expanded disability status score (EDSS).

Our study suggest that: (a ) diffuse changes are present in NAWM, (b) texture analysis is unable to detect any subtle structure in the NAWM abnormalities, possibly because of the limited image resolution; (c) in the development of disability in MS, macroscopic lesions are more important than microscopic abnormalities in the NAWM.
MRI in characterization of focal liver lesions: Comparison of T2 weighting by conventional spin‐echo and turbo spin‐echo sequences
Authors: Giovagnoni Andrea , Paci Enrico , Valeri Gianluca , Ercolani Paola , Gesuita Rosaria , Carle Flavia , Piga Andrea
Published: March 2007

Forty‐one patients with 61 proved focal liver lesions underwent MRI of the liver at 1.0 T, with the aim of evaluating the usefulness of turbo spin‐echo (TSE) sequences in characterizing focal liver lesions, by comparing them with conventional spin‐echo (CSE) sequences. Two different TSE protocols were employed, with constant echo time and varying repetition time: TSE‐S (3000 msec) and TSE‐L (5100 msec). All images were evaluated quantitatively (signal‐to‐noise ratio ‘SNR’) and qualitatively: because benign lesions were all liquid (12 cysts and 10 hemangiomas), they were well characterized morphologically on the basis of signal intensity.

Mean SNR was significantly different between metastases and benign lesions (P < .0001) with all T2 sequences. Among the single T2 sequences tested, logistic regression analysis showed TSE‐L to have the best predictive ability of the nature of focal lesions, with a G value of 42.02, compared to 29.87 of TSE‐S and 25.55 of CSE second echo (SE II). The combination of TSE‐L with TSE‐S did not modify these results, whereas the combination of TSE‐L with CSE only resulted in slight improvement (G = 46.95). Comparison of the receiver operating characteristic (ROC) curves showed only SE II (area under the ROC curve of .8312) to be significantly inferior to the best single sequence, or TSE‐L (area under the ROC curve of .9176; P = .027). All sequences were equivalent in qualitative evaluation, with good reproducibility, sensitivity ranging from .94 to 1.0, and specificity ranging from .86 to .93.

This study confirms the value of TSE sequences in characterization of focal liver lesions. Time of acquisition is strongly reduced with these sequences, whereas results are fairly similar to those obtained with CSE. TSE sequences could therefore replace CSE for the study of focal liver lesions.
Dynamic contrast‐enhanced breath‐hold MR imaging of thoracic malignancy using cardiac compensation
Authors: Low Russell N. , Sigeti Joel S. , Song S. Y. Thomas , Shimakawa Ann , Pelc Norbert J.
Published: March 2007

The purpose of this paper was to evaluate the use of dynamic gadopentetate dimeglumine‐enhanced, breath‐hold spoiled gradient‐recalled (SPGR) MR imaging with cardiac compensation (CMON) compared to spin‐echo MR imaging in patients with thoracic malignancy. We retrospectively reviewed MR images from 29 patients with thoracic tumors. MR imaging included axial electrocardiogram (ECG)‐gated T1‐weighted, fast spin echo (FSE) T2‐weighted, and contrast‐enhanced breath‐hold fast multiplanar SPGR imaging with CMON, which selects the phase‐encoding gradient based on the phase within the cardiac cycle. Images were reviewed for lung masses, mediastinal or hilar tumor, disease of the pleura, chest wall, and bones, and vascular compression or occlusion. Contrast‐enhanced fast multiplanar SPGR imaging with CMON produces images of the chest that are free of respiratory artifact and have diminished vascular pulsation artifact. ECG‐gated T1‐weighted images were preferred for depicting mediastinal and hilar tumor. The gadopentetate dimeglumine‐enhanced fast multiplanar SPGR images were useful for depicting chest wall tumor, vascular compression or thrombosis, osseous metastases, and in distinguishing a central tumor mass from peripheral lung consolidation. Pleural tumor was depicted best on the FSE T2‐weighted images and the contrast‐enhanced SPGR images. As an adjunct to spin echo T1‐weighted and T2‐weighted imaging, contrast‐enhanced fast multiplanar SPGR imaging with CMON is useful in the evaluation of thoracic malignancy.
The effect of image resolution on vessel signal in high‐resolution magnetic resonance angiography
Authors: Parker Dennis L. , Parker Daniel J. , Blatter Duane D. , Du Yiping P. , Goodrich Kenneth C.
Published: March 2007

In this paper, the theoretical dependence of the signal of flowing fluids is considered in terms of the imaging parameters and the physical condition of the flowing fluid. For the vessel sizes, flow ranges, and imaging conditions studied, it is demonstrated that the fluid signal can be predicted from the solution of Bloch equations. For vessels on the order of the imaging resolution or smaller, the effects of the image resolution must be included.
Sonochemically produced fluorocarbon microspheres: A new class of magnetic resonance imaging agent
Authors: Webb Andrew G. , Wong Mike , Kolbeck Kenneth J. , Magin Richard L. , Suslick Kenneth S.
Published: March 2007

With the intent of increasing the signal‐to‐noise ratio (SNR) of fluorine magnetic resonance imaging and enabling new applications, we have developed a novel class of agents based on protein encapsulation of fluorocarbons. Microspheres formed by high‐intensity ultrasound have a gaussian size distribution with an average diameter of 2.5 μm. As with conventional emulsions, these microspheres target the reticuloendothelial system. However, our sonochemically produced microspheres, because of a high encapsulation efficiency, show increases in the SNR of up to 300% compared to commercially available emulsions. We also demonstrate an increase in the circulation life‐time of the microspheres within the bloodstream by more than 30‐fold with a chemical modification of the outer surface of the microsphere. Finally, by encapsulating mixtures of fluorocarbons that undergo solid/liquid phase transitions, we can map temperature in the reticuloendothelial system, with signal changes of approximately 20‐fold over a 5°C range.
HASTE MR imaging: Description of technique and preliminary results in the abdomen
Authors: Semelka Richard C. , Kelekis Nikolaos L. , Thomasson David , Brown Mark A. , Laub Gerhard A.
Published: March 2007

HASTE (HAlf fourier Single‐shot Turbo spin‐Echo) is a single‐section T2‐weighted sequence that acquires images in less than 1 second. Images are breathing independent and possess a variety of other features useful for imaging the abdomen. The design of this technique is described. Clinical studies of 38 consecutive patients were performed using this technique. HASTE images were considered good in 28 and fair in 10 patients, including five patients who could not suspend respiration. Definition of liver and bowel was particularly clear.
Lesion volume measurement in multiple sclerosis: How important is accurate repositioning?
Authors: Gawne‐Cain Mary L. , Webb Stephanie , Tofts Paul , Miller David H.
Published: March 2007

This study was designed to estimate the contribution of repositioning inaccuracies to measured intracranial lesion volumes in multiple sclerosis (MS). Five patients with MS were each scanned 10 times, using spin‐echo imaging (2,000/34/90), contiguous 5‐mm slices, and different scanning positions. The maximum displacements from baseline were ±4° (AP rotation) and 3 mm (slice offset). Lesion volume was measured twice for each scan using a semiautomated contour technique. Measured lesion volumes ranged from 4,328 mm3 to 164,831 mm3. The mean intrarater coefficient of variation (CV) calculated for individual patients ranged from 1.1 to 4% (median, 1.7%). Using analysis of variance, the overall variance and CV due to altered scan position were greater than that due to rater error (repositioning CV 4.0%, intrarater CV 3.5%). The worst‐case difference between volumes in the same patient ranged from 8.9 to 32% (median, 9.9%). Both rater and repositioning errors were greater for smaller lesion volumes. The maximum potential error due to repositioning inaccuracies is of a similar magnitude to the 5 to 10% expected change in lesion volume over 1 year. This study justifies continued careful attention to accuracy in repositioning for serial MR studies in patients with MS.
Assessment of cerebral blood flow reserve using functional magnetic resonance imaging
Authors: Hedera Peter , Lai Song , Lewin Jonathan S. , Haacke E. Mark , Wu Dee , Lerner Alan J. , Friedland Robert P.
Published: March 2007

Imaging of activated brain areas based on changes of blood deoxyhemoglobin levels is now possible with MRI. Acetazolamide (ACZ) increases cerebral blood flow (CBF) without changing cerebral oxygen consumption; this results in signal changes observed in gradient echo MR images from the areas with an increase in CBF. We assessed signal changes after ACZ application in seven healthy subjects with a conventional 1.5‐T MRI scanner. The susceptibility‐sensitized three‐dimensional fast low‐angle shot (FLASH) sequence was used to visualize signal changes induced by ACZ. We analyzed anatomic localization of different ranges of detected signal changes. ACZ caused significant signal changes in the gray matter and at the edge of the cerebral cortex, the latter corresponding to draining surface veins. No significant differences were seen among different brain areas within the same slice. Using the maximum intensity projection technique, we were able to partially separate signal changes originating in draining veins from signal originating in the gray matter microvasculature. Signal changes from the microvessels reflect cerebrovascular reserve. Blood‐oxygen‐level‐dependent (BOLD) based MRI can evaluate CBF reserve with high spatial and temporal resolution. To assess cerebrovascular reserve, it is necessary to separate signal changes originating in large vessels from signal from brain microvasculature.
Hypogenetic lung syndrome: Functional and anatomic evaluation with magnetic resonance imaging and magnetic resonance angiography
Authors: Vrachliotis Thomas G. , Bis Kostaki G. , Shetty Anil N. , Simonetti Orlando , Madrazo Beatrice
Published: March 2007

A case of hypogenetic lung syndrome is described in which anatomic and functional information was obtained with use of ECG‐triggered turbo (fast) spin‐echo, cine, velocity‐encoded cine, and contrast‐enhanced magnetic resonance angiography (MRA) sequences. To the best of our knowledge, a complete functional and anatomic study of hypogenetic lung syndrome with MRI has not been previously reported.
A solid reusable endorectal receiver coil for magnetic resonance imaging of the prostate: Design, use, and comparison with an inflatable endorectal coil
Authors: Desouza Nandita M. , Gilderdale David J. , Puni Rakesh , Coutts Glyn A. , Young Ian R.
Published: March 2007

We have designed a solid endorectal receiver coil for MRI of the prostate. The coil provided an improved signal‐to‐noise ratio up to 5 cm from its surface when compared with a standard pelvic phased array. This preliminary report describes 16 patients who were imaged using this coil, seven of whom had been examined previously with a balloon‐design endorectal coil. Patient tolerance of these coils was compared. The solid coil was easy to insert and quick to set up because it did not require external tuning and matching. It avoided uncomfortable rectal distension experienced with the balloon coil as well as susceptibility artifacts from air in the balloon. In addition, it could be sterilized and reused.
Fast MR imaging techniques: Impact in the abdomen
Authors: Mitchell Donald G.
Published: March 2007

The increased efficiency of MRI data acquisition has had a substantial impact on clinical MRI of the abdomen. Five particular applications that have thus been affected include breath‐hold imaging of liver lesions (including detection, characterization, and biopsy), MR cholangiopan‐ creatography, practical chemical shift imaging (including liver and adrenal glands), dynamic imaging after contrast media injection, and MR angiography.
CT and MRI of stroke
Authors: Bahn Mark M. , Oser Allen B. , Cross Dewitte T.
Published: March 2007

A review of the CT and MRI features of stroke imaging is presented. The pathophysiology of stroke is discussed as a basis for understanding the neuroimaging findings. Neuroimaging is divided according to the time interval between ictus and imaging: hyperacute, acute, subacute, and chronic. Newer MR stroke imaging techniques such as perfusion imaging and diffusion‐weighted imaging are presented.
The role of T2‐weighted fast‐spin‐echo imaging in the diagnosis of meniscal tears
Authors: White Lawrence M. , Schweitzer Mark E. , Johnson William J. , Amster Bernard J. , Oliveri Marcelino P. , Russell Karen
Published: March 2007

The objective of this study was to compare the accuracy of T2‐weighted fast‐spin‐echo (FSE) and intermediate‐weighted spin‐echo (SE) MR imaging in the detection of meniscal tears. Seventy‐six patients (152 menisci) who had arthroscopic surgery after MR imaging of the knee were studied. MR imaging included intermediate‐weighted SE and T2‐weighted FSE sequences. The use of intermediate‐weighted conventional SE images, T2‐weighted FSE images, and a combination of both sequences were evaluated in the detection of meniscal tears. T2‐weighted FSE imaging was slightly less accurate than intermediate‐weighted SE imaging in the diagnosis of meniscal tears. Interpretation of the menisci using both intermediate‐weighted SE and T2‐weighted FSE imaging did not improve the accuracy over intermediate‐weighted imaging evaluated in isolation.
Chondromalacia of the knee: Evaluation with a fat‐suppression three‐dimensional SPGR imaging after intravenous contrast injection
Authors: Suh Jin‐Suck , Cho Jae‐Hyun , Shin Kyoo‐Ho , Kim Sung Jae
Published: March 2007

Twenty‐one MRI studies with a fat‐suppression three‐dimensional spoiled gradient‐recalled echo in a steady state (3D SPGR) pulse sequence after intravenous contrast injection were evaluated to assess the accuracy in depicting chondromalacia of the knee. On the basis of MR images, chondromalacia and its grade were determined in each of five articular cartilage regions (total, 105 regions) and then the results were compared to arthroscopic findings. The sensitivity, specificity, and accuracy of MRI were 70%, 99%, and 93%, respectively. MR images depicted 7 of 11 lesions of arthroscopic grade 1 or 2 chondromalacia, and seven of nine lesions of arthroscopic grade 3 or 4 chondromalacia. The cartilage abnormalities in all cases appeared as focal lesions with high signal intensity. Intravenous contrast‐injection, fat‐suppression 3D SPGR imaging showed high specificity in excluding cartilage abnormalities and may be considered as an alternative to intra‐articular MR arthrography when chondromalacia is suspected.
Theory and application of static field inhomogeneity effects in gradient‐echo imaging
Authors: Reichenbach Jürgen R. , Venkatesan Ramesh , Yablonskiy Dmitriy A. , Thompson Michael R. , Lai Song , Haacke E. Mark
Published: March 2007

The influence of local static magnetic field inhomogeneities on gradient‐echo imaging is discussed and the underlying theoretical aspects are reviewed. A high‐resolution approach is suggested to suppress image distortion and restore signal loss due to spin dephasing. Acquisition of three‐dimensional data sets not only overcomes part of the limitations associated with gradient echoes but also makes it possible to extract local information about the strength or direction of background gradients and relative susceptibility changes between different tissues. Applications of the suggested approach in the human brain for anatomical imaging as well as for extraction of physical and physiological parameters are presented and discussed.
Contrast‐enhanced MRA in pre‐embolization assessment of a pulmonary arteriovenous malformation
Authors: Vrachliotis Thomas G. , Bis Kostaki G. , Kirsch Matthias J. , Shetty Anil N.
Published: March 2007

We describe a case of a single pulmonary vascular malformation studied with a new contrast‐enhanced three‐dimensional MRA technique. Images provided the interventional radiologist with a pre‐embolization road map from which information regarding the number and size of feeding and draining vessels was obtained accurately and noninvasively.
Nutritional comparison of fresh, frozen, and canned fruits and vegetables II. Vitamin A and carotenoids, vitamin E, minerals and fiber
Authors: Rickman Joy C , Bruhn Christine M , Barrett Diane M
Published: March 2007

In this second part of our review, we examine the literature for changes in carotenoids, vitamin E, minerals, and fiber due to processing, storage, and cooking of fresh, frozen, and canned fruits and vegetables. While inconsistencies in methodology and reporting methods complicate interpretation of the data, the results show that these nutrients are generally similar in comparable fresh and processed products. The higher levels of carotenoids typically found in canned as compared to fresh products may be attributed to either reporting results on a wet rather than dry weight basis, greater extractability, or differences in cultivars. There are relatively few studies on processing, storage, and cooking effects on vitamin E in fruits and vegetables. Further research is needed to understand nutritional changes in those few fruits and vegetables rich in vitamin E, such as tomatoes. Minerals and fiber are generally stable to processing, storage, and cooking, but may be lost in peeling and other removal steps during processing. Mineral uptake (e.g., calcium) or addition (e.g., sodium) during processing can change the natural mineral composition of a product. Sodium concerns in canned food can be addressed by choosing products with no salt added. Since nutrient content varies considerably by commodity, cultivar, and postharvest treatments, inclusion of a wide variety of fruits and vegetables in the diet is encouraged. Copyright © 2007 Society of Chemical Industry
Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds
Authors: Rickman Joy C , Barrett Diane M , Bruhn Christine M
Published: March 2007

The first of a two‐part review of the recent and classical literature reveals that loss of nutrients in fresh products during storage and cooking may be more substantial than commonly perceived. Depending on the commodity, freezing and canning processes may preserve nutrient value. The initial thermal treatment of processed products can cause loss of water‐soluble and oxygen‐labile nutrients such as vitamin C and the B vitamins. However, these nutrients are relatively stable during subsequent canned storage owing to the lack of oxygen. Frozen products lose fewer nutrients initially because of the short heating time in blanching, but they lose more nutrients during storage owing to oxidation. Phenolic compounds are also water‐soluble and oxygen‐labile, but changes during processing, storage and cooking appear to be highly variable by commodity. Further studies would facilitate the understanding of the changes in these phytochemicals. Changes in moisture content during storage, cooking and processing can misrepresent changes in nutrient content. These findings indicate that exclusive recommendations of fresh produce ignore the nutrient benefits of canned and frozen products. Nutritional comparison would be facilitated if future research would express nutrient data on a dry weight basis to account for changes in moisture. Copyright © 2007 Society of Chemical Industry
Chemical fingerprint and quantitative analysis of Fructus Psoraleae by high‐performance liquid chromatography
Authors: Qiao Chun‐Feng , Han Quan‐Bin , Song Jing‐Zheng , Mo Shi‐Fu , Kong Ling‐Dong , Kung Hsiang‐Fu , Xu Hong‐Xi
Published: March 2007

Fructus Psoraleae, a widely used traditional Chinese medicine, is well known as a health supplement ingredient. In our study, an improved and comprehensive HPLC fingerprint of Fructus Psoraleae was established. Two important new benzofuran glycosides, psoralenoside and isopsoralenoside, were identified as characteristic constituents for the first time. HPLC separation was performed on an RP‐C8 column. The mobile phase was acetonitrile and 0.1% acetic acid solution with linear gradient change of acetonitrile from 10 to 82% in 40 min. The flow rate was 1.0 mL/min, and the detection wavelength was set at 310 nm. The HPLC chromatograms of twenty‐six samples from different regions of China showed a similar pattern. Twelve peaks were selected as characteristic peaks and further identified as psoralenoside, isopsoralenoside, psoralen, isopsoralen, bavachromene, corylifolin, corylin, psoralidin, isobavachalcone, bavachinin, corylifol A, and bakuchiol, respectively. Nine of them were simultaneously quantitatively analyzed for the first time. A more comprehensive analytical method was established for the fingerprint of Fructus Psoraleae. It is very useful for authentication and quality assessment of the crude drug.
Studies on degradation of imazalil enantiomers in soil using capillary electrophoresis
Authors: Chu Bao‐Lin , Guo Bao‐Yuan , Peng Zhenlei , Wang Zhihua , Guo Guangsheng , Lin Jin‐Ming
Published: March 2007

A scheme was demonstrated to elucidate the degradation behaviors of the two enantiomers of the fungicide imazalil in soil using cyclodextrin‐modified capillary zone electrophoresis. The separation buffer was 50 mmol/L NaH2PO4, 5 mmol/L (NH4)H2PO4, and 5 mmol/L β‐cyclodextrin (pH 3.0). The limits of detection of this CE method were 0.24 and 0.26 μg/mL for (–)‐ and (+)‐imazalil, respectively. Five different soil conditions were investigated in laboratory microcosms: under sunlight; in darkness; under UV irradiation; in sterilized soil; and in soil with wheat planted in it. Radiation, microorganisms, and uptake by wheat benefited the degradation of imazalil in this study. The half‐lives (t1/2) of imazalil in soil under the above conditions were 20, 30.5, 11, 27.5, and 21.5 days, respectively. The degradation rate of imazalil in soil under the five different sets of conditions decreased in the order: UV irradiation > sunlight > soil with wheat planted in it > sterilized soil > soil kept in darkness. Imazalil in soil (pH 8.2, slightly alkaline) collected in the suburbs showed non‐enantioselective degradation.
Rapid qualitative and quantitative analyses of flavanone aglycones in Fructus aurantii by HPLC ion‐trap MS
Authors: Zhou Da‐yong , Xu Qing , Xue Xing‐ya , Zhang Fei‐fang , Jing Yu , Liang Xin‐miao
Published: March 2007

IT‐MS operated in the positive mode was applied for the rapid characterization/quantification of the flavanones in extracts from Fructus aurantii. APCI‐MS and CID MS/MS provide unequivocal molecular weight (MW) data of these compounds and useful information about their structures (diagnostic fragment ions). Main fragment pathways include neutral losses of H2O, C2H2O, and B‐ring as well as a retro‐Diels‐Alder (RDA) fragment giving rise to [1,3A + H]+, [1,3B + H]+, and [1,4B–H2 + H]+ ions, which form the characteristic MS/MS “fingerprint” of flavanone aglycones. When screening extracts of F. aurantii for flavanone aglycones, eight target compounds were characterized using this fingerprint. Meanwhile, ESI‐MS in full‐scan mode was developed and validated for the quantification of the main flavanone aglycones in F. aurantii. This method is simple, accurate, fast and requires only 16 min per sample for direct detection and quantification of naringenin and hesperetin. All the results and these characteristic fragments showed that the IT‐MS is a powerful tool for the structural characterization and quantitative determination of flavanone aglycones.
Recent development of monolithic materials as matrices in microcolumn separation systems
Authors: Zhu Guijie , Zhang Lihua , Yuan Huiming , Liang Zhen , Zhang Weibing , Zhang Yukui
Published: March 2007

This review summarizes the development of monolithic materials, including both organic and inorganic polymers, according mainly to the papers published in the past two years. Due to their good permeability, fast mass transfer, high stability, and their ease of modification, such materials have been widely used in microcolumn separation systems, not only as stationary phases for CEC and capillary HPLC, but also as substances for sample concentration and enzyme reactor. All the research results demonstrate that monolithic materials in microseparation systems can be expected to play an increasingly important role in the analysis of complex samples.
Vinylogous Amadori rearrangement: Implications in food and biological systems
Authors: Yaylayan Varoujan A. , Locas Carolina P.
Published: March 2007

The 4‐hydroxy‐alkenals are important lipid peroxidation products and are known to play a major role both in the development of degenerative diseases in biological systems and off‐flavors, or rancidity in food systems. The 4‐hydroxy‐alkenals can also be formed in nonlipid systems from 2‐deoxy‐sugar moieties such as 2‐deoxy‐ribose. FTIR spectroscopic evidence was provided for such a transformation catalyzed by amino acids through monitoring the decrease in intensity of the aldehydic band centered at 1716 cm–1 of the open form of 2‐deoxy‐ribose and increase in the intensity of the formed conjugated aldehydic band centered at 1672 cm–1. Furthermore, 4‐hydroxy‐alkenals can react with nitrogen nucleophiles such as amino acids and proteins to form Schiff base adducts that are able to undergo vinylogous Amadori rearrangement (vARP) and subsequently cyclize to generate a pyrrole moiety. This cyclization is prevented in the case of secondary amino acids such as proline to form a stable vinylogous Amadori rearrangement product (vARP). Monitoring this reaction of proline with 4‐hydroxy‐2‐nonenal (HNE) has indicated that within 15 min at 28°C the 1685 cm–1 band of HNE completely disappears and that at 50°C, vARP is formed within 5 min, as indicated by the formation of a characteristic band at 1709 cm–1.
Maillard reaction products enriched food extract reduce the expression of myofibroblast phenotype markers
Authors: Ruhs Stefanie , Nass Norbert , Somoza Veronika , Friess Ulrich , Schinzel Reinhard , Silber Rolf‐Edgar , Simm Andreas
Published: March 2007

Advanced glycation end products (AGE) are associated with a wide range of degenerative diseases. The present investigation aimed at analysing the influence of AGE containing nutritional extracts on cardiac fibroblasts (CFs) as the major cell type responsible for cardiac fibrosis. Mice CFs were treated with bread crust extract (BCE) which contained significant amounts of a variety of AGE modifications. BCE treatment with up to 30 mg/mL did not impair cell viability. Furthermore, BCE induced a moderate elevation of reactive oxygen species (ROS) production and activation of redox sensitive pathways like the p42/44MAPK, p38MAPK and NF‐κB but did not alter Akt kinase phosphorylation. Expression of smooth muscle α‐actin and tropomyosin‐1, which represent markers for myofibroblast differentiation, was reduced after bread crust treatment. These data suggest a putative antifibrotic effect of melanoidin‐rich food.
Parameters for the evaluation of the thermal damage and nutraceutical potential of lupin‐based ingredients and food products
Authors: Arnoldi Anna , Resta Donatella , Brambilla Francesca , Boschin Giovanna , D'Agostina Alessandra , Sirtori Elena , O'Kane Francesca
Published: March 2007

Foods based on sweet lupin proteins are gaining attention from industry and consumers because of their possible role in the prevention of cardiovascular disease. When promoting lupin‐based foods for inclusion in a daily diet, the thermal damage suffered during processing is of relevance to the bioactive and nutritional quality of the food product. N‐(2‐furoylmethyl)‐L‐lysine (furosine) quantification demonstrates that currently available sweet lupin protein isolates have a thermal damage comparable to or lower than other traditional food ingredients, and are a good source of lysine in non‐dairy products. In lupin‐based foods claiming to have cholesterol‐lowering potential, shotgun proteomics offers itself as a fast and effective screening method for assessing the biological availability of active peptides. Such a method is readily applicable to other legume‐enriched food products.
Formation of 5‐hydroxymethyl‐2‐furfural (HMF) and 5‐hydroxymethyl‐2‐furoic acid during roasting of coffee
Authors: Murkovic Michael , Bornik Maria‐Anna
Published: March 2007

The formation of 5‐hydroxymethyl‐2‐furfural (HMF) and 5‐hydroxymethyl‐2‐furoic acid (HMFA) during roasting of coffee was studied. At 240°C the maximum concentration of HMF occurs after 3 min with a quick degradation up to 10 min when most of the HMF has disappeared again. Similar to 5‐hydroxymethyl‐furfural, HMFA is formed in coffee but not in a model system consisting of sucrose, alanine with or without chlorogenic acid. It was shown that HMFA is produced from different precursors than HMF namely glyceraldehyde and pyruvate. The comparison of the laboratory scale roasting with industrial roasting showed that 5‐hydroxymethyl‐furfural decreases with a higher degree of roasting whereas HMFA did not change. In the laboratory scale experiments, the highest concentration of 5‐hydroxymethyl‐furfural in coffee (909 μg/g) was obtained after 3 min and the maximum concentration of HMFA after 4 min (150 μg/g). Industrially roasted coffee contained up to 350 μg/g 5‐hydroxymethyl‐furfural and 140 μg/g HMFA.
Measurement of perfusion rate in human melanoma xenografts by contrast‐enhanced magnetic resonance imaging
Authors: Lyng Heidi , Dahle Gro A. , Kaalhus Olav , Skretting Arne , Rofstad Einar K.
Published: March 2007

Reliable methods based on MRI for measurement of the perfusion rate in human tumors are highly warranted. Tumors of two amelanotic human melanoma xenograft lines were subjected to dynamic 1H MRI after i.v. administration of gado‐pentetate dimeglumine (Gd‐DTPA). The aim was to investigate to what extent different perfusion parameters determined from the Gd‐DTPA kinetics, i.e., the initial uptake rate, the maximal uptake, the decay rate, and the perfusion rate calculated by use of the Kety equation, can be used as a reliable estimate of tumor perfusion rate. Each parameter was calculated in dual; one calculation was based on relative signal intensity increase (RSII) in T1‐weighted MR images and the other on Gd‐DTPA concentration determined from the images. The perfusion parameters were compared with the perfusion rates determined from measurement of tumor uptake of 86Rb or [14C]iodoantipyrine. The results showed that reliable estimates of tumor perfusion rate can be achieved from analysis of Gd‐DTPA kinetics by use of the Kety equation. Gd‐DTPA kinetics based on concentration might be used to achieve reliable estimates of absolute tumor perfusion rate, whereas reliable estimates of the relative perfusion rate might also be achieved from Gd‐DTPA kinetics based on RSII. The initial uptake rate, the maximal uptake, and the decay rate of Gd‐DTPA, however, are not reliable estimates of tumor perfusion rate, mainly because these parameters are highly influenced by the tumor extracellular volume fraction in addition to the perfusion rate.
Dynamic k‐space filling for bolus chase 3D MR digital subtraction angiography
Authors: Lee Howard M. , Wang Yi
Published: March 2007

A bolus chase three‐dimensional (3D) MR digital subtraction angiography (MRDSA) technique was implemented using dynamic k‐space filling. This technique permits rapid 3D arterial imaging of the entire lower extremity at multiple stations using a single intravenous injection. Image acquisition at the first (most proximal) station starts from the edge of k‐space and ends in the center of k‐space (edge‐center order). Image acquisition for middle stations starts from the edge of k‐space, arrives at the center of k‐space at the middle of data acquisition, and ends at the edge of k‐space (edge‐center‐edge order). Image acquisition for the last station starts from the center of k‐space and ends at the edge of k‐space (center‐edge order). This dynamic k‐space filling minimizes contrast dose and motion artifacts. Bolus chase 3D MRDSA was performed on four normal volunteers and three patients using a multiple‐phase 3D fast gradient‐echo sequence, 25‐ml gadolinium dose, and a prototype stepping table. Total bolus chase 3D acquisition time was 46 s. Mask subtraction using both complex and magnitude subtraction was performed. Complex subtraction was found to be necessary for proper delineation of arteries below the aortic bifurcation. Diagnostic results were consistently obtained for all subjects.
Signal undershoots following visual stimulation: A comparison of gradient and spin‐echo BOLD sequences
Authors: Jones Richard A. , Schirmer Timo , Lipinski Bernadette , Elbel Gregor K. , Auer Dorothee P.
Published: March 2007

Gradient‐echo (GRE) and spin‐echo (SE) EPI BOLD sequences were used to quantitate the effect of visual stimulation. Both sequences showed a positive BOLD response during stimulation and a negative BOLD response in the interstimulation intervals. The relaxation rate changes during stimulation were larger for the GRE sequence than for the SE sequence, whereas in the interstimulation intervals they were not significantly different. In both cases, the ratio of the GRE/SE relaxation rate changes were consistent with BOLD effects in larger vessels despite the well‐known lower sensitivity of the SE sequence to the extravascular component of the BOLD effect in larger vessels. The most probable explanation of this result is that a significant fraction of the observed changes originated from the intravascular component of the BOLD effect. The SE sequence depicted smaller areas of activation than the GRE sequence with more than 85% of the pixels being depicted as significant by the SE sequence being also significant in the GRE activation maps. However, for the reverse comparison, an overlap of only 35% was observed, with many of the strongly correlated GRE pixels showing weak correlations in the corresponding SE activation image. Our results, together with the fact that signal undershoots have not been observed by groups using MR sequences that measure absolute flow changes for similar stimulation paradigms, suggest that the undershoot may be due to alterations in the blood volume and/or hematocrit during stimulation that normalize at a slower rate than the changes in blood flow after the cessation of the stimulation, leading to a poststimulation signal undershoot.
Gadolinium‐bearing red cells as blood pool MRI contrast agents
Authors: Johnson Kevin M. , Tao Jing Zang , Kennan Richard P. , Gore John C.
Published: March 2007

Human and rat red blood cells (RBCs) were loaded with gadolinium DTPA dimeglumine using an osmotic pulse technique to create a blood pool contrast agent for MRI. The resulting packed red cells contained 30.9 ± 3.3 (1 SD) mmol Gd/literfor humans and 24.7 ± 3.5 (1 SD) mmol Gd/liter for rats. Longitudinal relaxation rate constant of human RBCs increased from 2.0 ± 0.1 to 145.6 ± 36.2 s−1; the transverse relaxation rate constant increased from 6.8 ± 1.2 to 562 ± 410 s−1. For rat RBCs, R1 increased from 1.45 ± 0.15 to 84.8 ± 23.9 s−1; R2 increased from 7.1 ± O.64 to 247 ± 158 s−1. Affinity for oxygen was slightly reduced (control P50 = 22.3 ± 2.3 versus experimental P50 = 27.3 ± 1.3, P < 0.01), as was mechanical de‐formability. No drop in relaxivities was seen after 5 days of storage. The apparent volume of distribution was 0.0164 ± 0.003 liter/kg, biologic half‐life 4.38 ± 0.34 h, and total plasma clearance 0.003 ± 0.0006 liter/kg/h. Compared with Gd‐DTPA “free” in the plasma, tissue enhancement from RBCs was initially lower but was much prolonged. Preparation is simple enough to be reproduced by most laboratories.