bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐ablative laser treatment of facial rhytides: A comparison of 1450‐nm diode laser treatment with dynamic cooling as opposed to treatment with dynamic cooling alone
Authors: Goldberg David J. , Rogachefsky Arlene S. , Silapunt Sirunya
Published: October 2004

Background and Objective

Non‐ablative dermal remodeling has been shown to create new dermal collagen. This is thought to occur secondary to a laser‐induced injury to the skin. Other mechanisms of injury may lead to similar results. The aim of this study was to evaluate the efficacy and complication rate of a 1450‐nm diode laser and compare clinical effect when the laser is used in conjunction with cryogen cooling as compared to the use of cryogen cooling alone.

Study Design/Materials and Methods

Twenty subjects, skin types I–IV, age range 42–70 years, with Class I and II rhytides were enrolled in the study. Subjects were treated with 2–4 laser treatments and cryogen cooling on one side of their face, while the contralateral side was treated with cryogen cooling alone. Subjects were evaluated six months after their final treatment.

Results

Thirteen subjects showed clinical improvement on the laser/cryogen treated side. No subjects were noted to have any improvement at the cryogen alone side.

Conclusion

The 1450‐nm diode laser can lead to non‐ablative improvement of rhytides. This effect appears to be a direct laser induced effect. Lasers Surg. Med. 30:79–81, 2002. © 2002 Wiley‐Liss, Inc.
Pulsed dye laser and intralesional bleomycin for treatment of resistant viol hand warts
Authors: Pollock B. , Sheehan‐Dare R.
Published: October 2004

Background and Objective

Viral warts affect 7–10% ofthe population and are a major burden on time and resources of dermatology departments everywhere. Some warts prove resistant to multiple therapies, and this is particularly common in the immunosuppressed patient. Numerous treatments are available, but no one treatment has emerged as the treatment of choice. Bleomycin has been shown to be effective in treating warts, but administration can be difficult with risk of local complications. To demonstrate a new technique for easily and safely administrating bleomycin into warts, we undertook an open study to assess the practicality, efficacy, and tolerability of pulsed dye laser immediately followed by intralesional bleomycin in resistant viral hand warts.

Study Design/Materials and Methods

Ten subjects, all with resistant viral hand warts of at least 3 years duration were recruited. Four subjects were on long‐term immunosuppressant drugs. Eighteen warts treated in total. Area of the wart was anaesthetized with 1% lignocaine, then treated with a pulsed dye laser (7 mm spot, fluence 10 J/cm2). Immediately following this bleomycin (0.5 IU/ml) was injected into the base of the wart. Monthly follow‐up and treatment until satisfactory clearance.

Results

Sixteen out of eighteen warts cleared (89%). Eight out of ten warts in the immunosuppressed subjects cleared. The remaining two warts responded partially to two treatments, but the patient was happy with the result and did not wish further treatment. All warts in the immunocompetent subjects cleared. No serious side effects were seen.

Conclusions

The initial treatment of the wart with pulsed dye laser serves to “prepare” the wart for the bleomycin injection, which can then be given very easily. This ensures the drug is deposited into the base of the wart where it is most needed and minimises the risk of infiltration of normal skin or the operative environment. This method of combining pulsed dye laser and intralesional bleomycin appears to be a safe, rapid, well tolerated, and successful treatment for resistant hand warts. It has proven to be effective in warts in immunosuppressed patients and at difficult sites (e.g., subungual warts). These findings need confirmation from a larger controlled study. Lasers Surg. Med. 30:135–140, 2002. © 2002 Wiley‐Liss, Inc.
Comparative pilot study evaluating the treatment of leg veins with a long pulse ND:YAG laser and sclerotherapy*
Authors: Coles Charlotte M. , Werner Richard S. , Zelickson Brian D.
Published: October 2004

Background and Objective

To date there have been very few side by side comparison studies of laser versus sclerotherapy in treating small leg veins. This study compares a long pulsed Nd:YAG laser with contact cooling to sclerotherapy for treating small diameter leg veins by evaluating objective and subjective clinical effects.

Study Design/Materials and Methods

Twenty patients were selected with leg veins ranging from 0.25 to 3 mm at two comparable sites. One site was treated with long pulsed Nd:YAG laser and the other received sotradecol sclerotherapy. The patients followed up at 8 weeks for another possible laser retreatment and 3 months following the last treatment. Photographs were taken pre‐ and post‐operatively and at each follow‐up visit and used for objective comparative analysis. The patients also completed a Quality of Life survey.

Results

Improvement was tabulated from the photographic assessment on an improvement scale from 0 (no change)–4 (greater than 75% clearing). The laser treated areas averaged 2.50 and sclerotherapy treated sites averaged 2.30. Patient surveys show 35% preferred laser and 45% choose sclerotherapy.

Conclusion

This pilot study demonstrates that the Lyra Long Pulse Nd:YAG laser can yield results similar to sclerotherapy in the treatment of small leg veins. Lasers Surg. Med. 30:154–159, 2002. © 2002 Wiley‐Liss, Inc.
Use of a novel erbium laser in a Yucatan minipig: A study of residual thermal damage, ablation, and wound healing as a function of pulse duration†
Authors: Ross Edward V. , McKinlay Joseph R. , Sajben Francis P. , Miller Charles H. , Barnette David J. , Meehan Kenneth J. , Chhieng Norak P. , Deavers Mickey J. , Zelickson Brian D.
Published: October 2004

Background and Objective

Theoretical models show that varying pulse duration influences residual thermal damage in erbium YAG skin resurfacing. Accordingly, our objective was to compare residual thermal damage, ablation, tissue shrinkage, and wound healing between a variable pulsewidth erbium YAG laser and a popular CO2 resurfacing laser.

Study Design/Materials and Methods

The erbium laser delivered a typical ablative pulse (250 microseconds), followed by a heating pulse of variable duration. Pulse durations for specific coagulation depths were selected based on existing heat transfer models. The bilateral flanks of one Yucatan pig were irradiated. Eight sites were treated per group. Biopsies were performed just after treatment and 1, 3, 7, 21, and 60 days postoperatively.

Results

Just after irradiation, gross examination of “cold” (without a coagulation pulse) erbium sites showed a reddish papillary dermis consistent with conventional erbium laser ablation. Two and three pass CO2 sites showed uniform surface yellowing. The longer pulsewidth (“hot”) erbium groups showed only slight surface yellowing. Biopsies showed immediate thermal damage that increased with erbium pulse duration; however, actual residual thermal damage (RTD) was sometimes less than that predicted by the laser control panel. All wounds healed uneventfully by 14 days.

Conclusions

An erbium laser with a variable macropulse pulsewidth was capable of achieving RTD of up to 80 μm. Even greater RTD depths may be obtainable with future manipulations of fluence and pulse duration. Lasers Surg. Med. 30:93–100, 2002. © 2002 Wiley‐Liss, Inc.
Hair removal with the long pulsed Nd:YAG laser: A prospective study with one year follow‐up
Authors: Lorenz Susanne , Brunnberg Stephanie , Landthaler Michael , Hohenleutner Ulrich
Published: October 2004

Background and Objective

The aim was to investigate the efficacy, side effects, and the long‐term results of a long pulsed Nd:YAG‐Laser for hair removal in different hair colors and skin types.

Study Design/Materials and Methods

We performed a prospective clinical study with 29 volunteers. Treatment was performed on the lower leg with a long pulsed Nd:YAG‐Laser. Five test areas were treated 1–5 times in monthly intervals; one served as control. Follow‐up investigations were performed at each session, and 3, 6, and 12 months after the last therapy. No depilatory treatment except shaving was allowed during the time of follow‐up. Percentual hair loss, short‐ and long‐term side effects, and pain during the treatment were evaluated.

Results

After one month, a hair loss of greater than 50% was found in 44.9% of the areas treated once. With up to five treatments, this percentage increased up to 71.5%. One year after therapy, a greater than 50% hair reduction was still present in 40% of the five‐treatment‐areas and in 0% of the areas treated only once. There were no permanent side effects despite one small scar after a folliculitis.

Conclusions

The long pulsed Nd:YAG is suitable to remove hair for more than 12 months effectively, although 4–5 sessions are necessary for these results. Blond hair can also be removed, although much less effective. No lasting side effects could be seen. Darker skin types or tanned skin can also be treated without side effects. A cooling may be advisable due to the pain reported by the volunteers. Lasers Surg. Med. 30:127–134, 2002. © 2002 Wiley‐Liss, Inc.
MMPs and TIMP‐1 are differentially expressed between acute murine excisional and laser wounds
Authors: Draper Bradley K. , Davidson Mari K. , Nanney Lillian B.
Published: October 2004

Background and Objectives

Matrix metalloproteinases (MMPs) and their physiological inhibitors, the tissue inhibitors of metalloproteinases (TIMPs) play significant roles in wound repair. The aim of this study was to determine whether MMP and TIMP‐1 mRNA is differentially expressed between laser‐created and excisional skin wounds.

Study Design/Materials and Methods

Full‐thickness wounds were created on the dorsal surface of Balb/c mice by either excision of the skin or with a CO2 laser. Animals were sacrificed at days 1, 3, 5, 7, 10, and 13, and their wounds processed for RNA isolation or histology and immunohistochemistry.

Results

Northern hybridization for MMP‐3, ‐10, ‐13, and TIMP‐1 mRNA demonstrated higher expression on days 1, 3, and 5 in the laser wounds as compared to the excisional wounds. Histological evaluation revealed a two day delay in the resurfacing of laser wounds as compared to excisional wounds. Immunohistochemistry of Day 5 and 7 excisional and laser wounds showed MMP‐3 within the epidermal compartment and the neo‐dermis. No remarkable differences were noted in the spatial distribution patterns of MMP‐3 between wound types.

Conclusions

Our findings demonstrate that MMPs and TIMP‐1 mRNA expression is higher on days 1–5 post injury in full thickness laser‐created wounds than in comparable same day excisional wounds. Lasers Surg. Med. 30:106–116, 2002. © 2002 Wiley‐Liss, Inc.
Evaluating the efficacy of using a short‐pulsed erbium:YAG laser for intraoperative resurfacing of surgical wounds
Authors: Rohrer Thomas E. , Ugent Steven J.
Published: October 2004

Background and Objective

There are many studies demonstrating the aesthetic benefits of resurfacing a wound 4–8 weeks following surgical closure. Several anecdotal reports have been published stating that resurfacing a wound at the time of closure is also of cosmetic benefit. Our study was designed to evaluate the effects of resurfacing wound edges at the time of surgical closure.

Study Design/Materials and Methods

Ten patients with skin types I–III undergoing reconstruction on the head or neck using a complex linear closure of at least 4 cm in length were enrolled in the study. Following the placement of subcutaneous sutures and an intradermal running suture, a split scar study was designed. Half of the wound was left as a control and half of the wound was resurfaced with a short pulsed Erbium:YAG laser. Both sides were treated with a hydrogel dressing. Follow‐up evaluations were performed 1 week, 1 month, and 3 months post‐operatively. The wound was evaluated for any adverse reactions. The degree of erythema, textural misalignment or tissue mismatch, and overall aesthetic appearance of both sides of the scar were evaluated and scored.

Results

There were no incidents of infection, dehiscence, hematoma, necrosis, or reaction to the dressing during the study. There was a trend towards greater erythema in the resurfaced half of the scar at the 1 week and 1 month evaluation. There was a trend towards less tissue mismatch and better overall aesthetic appearance of the side of the scar that had been resurfaced. The differences however were not statistically significant.

Conclusion

Given the time and resources necessary to perform an intraoperative resurfacing procedure on the wound edges, it may be more reasonable to withhold resurfacing procedures for those few cases that may require it postoperatively (patients with a history of poor healing, highly sebaceous areas, etc.). When good operative technique is used, most surgical wounds on the head and neck heal very well with excellent aesthetic outcomes without any additional intervention. Lasers Surg. Med. 30:101–105, 2002. © 2002 Wiley‐Liss, Inc.
Zoon's balanitis treated with Erbium:YAG laser ablation†
Authors: Albertini John G. , Holck David E.E. , Farley Mary F.
Published: October 2004

Background and Objective

Zoon's balanitis (ZB) is an uncommon, benign, idiopathic inflammatory condition affecting uncircumcised males. Definitive treatments include circumcision and carbon dioxide (CO2) laser ablation. We describe an alternative laser modality showing efficacy in the treatment of ZB.

Study Design/Materials and Methods

We report the first case of ZB effectively treated with Erbium:YAG (Er:YAG) laser ablation. We review the pathogenesis and medical, surgical, and laser management of ZB.

Results

Our patient demonstrated a long‐term clinical and histologic cure after Er:YAG laser ablation of ZB.

Conclusions

As an alternative to circumcision or continuous wave CO2 laser, we propose a trial of Er:YAG laser ablation as a low risk, first line treatment of ZB. Lasers Surg. Med. 30:123–126, 2002. © 2002 Wiley‐Liss, Inc.
Cooling gel improves pulsed KTP laser treatment of facial telangiectasia
Authors: Kauvar Arielle N.B. , Frew Kathryn E. , Friedman Paul M. , Geronemus Roy G.
Published: October 2004

Background and Objective

Pulsed KTP lasers effectively treat facial telangiectasia without purpura production. Transient side effects following treatment include erythema, edema, and vesiculation leading to crust formation. The aim of this study was to investigate the utility of an aqueous gel in reducing side effects associated with pulsed KTP laser treatment of facial telangiectasia.

Study Design/Materials and Methods

Nineteen patients with extensive facial telangiectasias were treated with a pulsed KTP laser (Versapulse, Coherent, Palo Alto, CA). The laser was used with the water cooled handpiece chilled to 4°C, a 4 mm spot size, a 10‐millisecond pulse duration and a fluence of 9.5 J/cm2. One side of the face was treated with the laser using the cooling handpiece alone. The other side was treated using the cooling handpiece applied to a 2‐mm film of aqueous gel spread over the treatment area.

Results

Treatment side effects, including pain, erythema, edema, vesiculation, and crusting were scored following treatment with and without the aqueous gel. Use of the aqueous gel in conjunction with the cooling handpiece decreased the incidence and severity of pain, erythema, edema, and crusting following pulsed KTP laser treatment of facial telangiectasia. Most patients demonstrated 50–75% clearance of their telangiectasias 1 month after one treatment session, and use of the gel did not alter the treatment efficacy.

Conclusions

The application of an aqueous gel during pulsed KTP laser treatment of facial telangiectasia improves treatment associated side effects without affecting vessel clearance. Lasers Surg. Med. 30:149–153, 2002. © 2002 Wiley‐Liss, Inc.
Extended theory of selective photothermolysis
Authors: Altshuler G.B. , Anderson R.R. , Manstein D. , Zenzie H.H. , Smirnov M.Z.
Published: October 2004

Background and Objective

We present a new theory of selective thermal damage of non‐uniformly pigmented structures in biological tissues. Spatial separation of the heavily pigmented areas and the target requires limitation of the pigment temperature and heat diffusion from the pigmented to the targeted areas.

Study Design/Materials and Methods

A concept of selective target damage by heat diffusion is presented for three target geometries: planar, cylindrical, and spherical. An in vitro experiment is described in which the dependence of thermal damage on pulsewidth at constant fluence was evaluated.

Results

The in vitro experiment showed that the size of the damage zone for similar hair follicles was pulsewidth‐independent over a very broad range of pulsewidths (30–400 ms). We formulated a new theory (extended theory of photothermolysis) to interpret the experimental results.

Conclusions

Based on this new theory, the treatment pulsewidth for non‐uniformly pigmented targets is significantly longer than the target thermal relaxation time (TRT). The theory provides new recommendations for photoepilation and photosclerotherapy parameters. Lasers Surg. Med. 29:416–432, 2001. © 2001 Wiley‐Liss, Inc.
Helium‐Neon laser irradiation of hepatocytes can trigger increase of the mitochondrial membrane potential and can stimulate c‐fos expression in a Ca2+‐dependent manner
Authors: Greco Margherita , Vacca Rosa A. , Moro Loredana , Perlino Elda , Petragallo Vito A. , Marra Ersilia , Passarella Salvatore
Published: October 2004

Background and Objective

To gain some insight into the photostimulation of isolated hepatocytes irradiated with Helium‐Neon (He‐Ne) laser light certain biochemical events were studied with respect to two mechanisms: i) the direct light dependent activation of certain biochemical events investigated in intact cells and isolated mitochondria, ii) the indirect stimulation of processes per se light independent.

Study Design/Materials and Methods

Irradiation of either isolated hepatocytes or isolated rat liver mitochondria was carried out with He‐Ne laser (wavelength, 632.8 nm; fluence, 0.24 J cm−2; fluence rate, 12 mW cm−2). Changes in mitochondrial membrane potential in isolated hepatocytes were monitored using the cationic probe safranine. The c‐fos expression was studied by Northern blot and immunoblot analysis.

Results

As a result of irradiation, increase of the mitochondrial membrane potential was found to occur in irradiated hepatocytes both in the presence or in the absence of CaCl2. The hyperpolarization of the mitochondrial membrane is assumed to cause an increase in mitochondrial Ca2+ uptake that was measured in isolated mitochondria. Finally, an increase in c‐fos expression was found in irradiated hepatocytes when incubated in the presence of CaCl2.

Conclusion

This paper gives additional information on the mechanism by which He‐Ne laser light, either directly or in a cascade‐like effect dependent on increase in cell Ca2+, can cause cell stimulation. Lasers Surg. Med. 29:433–441, 2001. © 2001 Wiley‐Liss, Inc.
The psychology of deception in marketing: A conceptual framework for research and practice
Authors: Aditya Ram N.
Published: October 2004

The Federal Trade Commission's current policy statements on deceptive and unfair marketing practices are predicated primarily on economic considerations, ignoring the broader ramifications of trade policy for society as well as specific considerations with regard to the individual consumer. In part, this is due to the fact that research in this area has addressed only isolated aspects of the problem of deception in marketing. This article takes a pluralistic perspective on the issue in an attempt to stimulate research into hitherto unexplored avenues and provide a platform for future policy. The relevant psychological processes in consumer behavior are discussed in the light of product attributes and situational characteristics in a framework that takes into account the needs of the individual as well as the broader values of society. © 2001 John Wiley & Sons, Inc.
Characterization of intact microorganisms by MALDI mass spectrometry
Authors: Fenselau Catherine , Demirev Plamen A.
Published: October 2004

I.
Introduction
157

II.
MALDI‐TOF Spectra of Biomarkers
158

III.
Instrumentation
158

IV.
Sample Introduction
160

V.
Preparation of Microorganism Samples for MALDI Analysis
161

VI.
Characterization of MALDI Biomarkers
162

VII.
Data Analysis: Fingerprint Libraries, Statistical Methods, Bioinformatics
163

VIII.
Applications
165

IX.
Summary and Envoi
166

Acknowledgments
166

References
166

The application of MALDI mass spectrometry to desorb protein biomarkers from intact viruses, bacteria, fungus, and spores is the focus of this review. Instrumentation, sample collection, sample preparation, and algorithms for data analysis are summarized. Optimally these analyses should be carried out in less than five minutes. Successful applications are discussed from biotechnology, cell biology, and the pharmaceutical industry. © 2002 John Wiley & Sons, Inc., Mass Spec Rev 20:157–171, 2001
Cyclopentenone prostaglandins: New insights on biological activities and cellular targets
Authors: Straus Daniel S. , Glass Christopher K.
Published: October 2004

The cyclopentenone prostaglandins PGA2, PGA1, and PGJ2 are formed by dehydration within the cyclopentane ring of PGE2, PGE1, and PGD2. PGJ2 is metabolized further to yield Δ12‐PGJ2 and 15‐deoxy‐Δ12,14‐PGJ2 (15d‐PGJ2). Various compounds within the cyclopentenone prostaglandin family possess potent anti‐inflammatory, anti‐neoplastic, and anti‐viral activity. Most actions of the cyclopentenone prostaglandins do not appear to be mediated by binding to G‐protein coupled prostanoid receptors. Rather, the bioactivity of these compounds results from their interaction with other cellular target proteins. 15‐deoxy‐Δ12,14‐PGJ2 is a high affinity ligand for the nuclear receptor PPARγ and modulates gene transcription by binding to this receptor. Other activities of the cyclopentenone prostaglandins are mediated by the reactive α,β‐unsaturated carbonyl group located in the cyclopentenone ring. The transcription factor NF‐κB and its activating kinase are key targets for the anti‐inflammatory activity of 15d‐PGJ2, which inhibits NF‐κB‐mediated transcriptional activation by PPARγ‐dependent and independent molecular mechanisms. Other cyclopentenone prostaglandins, such as Δ7‐PGA1 and Δ12‐PGJ2, have strong anti‐tumor activity. These compounds induce cell cycle arrest or apoptosis of tumor cells depending on the cell type and treatment conditions. We review here recent progress in understanding the mechanisms of action of the cyclopentenone prostaglandins and their possible use as therapeutic agents. © 2001 John Wiley & Sons, Inc. Med Res Rev, 21, No. 3, 185–210, 2001
Temporal frequency analysis of dynamic MRI techniques
Authors: Wu Yijing , Alexander Andrew L.
Published: October 2004

Dynamic imaging strategies often involve updating certain areas of k‐space (i.e., the low spatial frequencies) more frequently than others. However, important dynamic signal changes may occur anywhere in k‐space. In this study, a dynamic k‐space sampling analysis method was developed to determine the energy error associated with specific dynamic sampling strategies. The method uses the temporal power spectrum of k‐space signals to determine the level and k‐space locations of sampling errors. The proposed method was used to compare two dynamic sampling strategies (full sequential and keyhole) for a dynamic first‐pass bolus simulation and a continuous heart imaging study. The error analysis agreed well with the errors in the reconstructed images. The technique can be used to determine the minimum sampling frequency for any location in the k‐space, and may ultimately be used to optimize dynamic sampling strategies. Magn Reson Med 45:550–556, 2001. © 2001 Wiley‐Liss, Inc.
Physiological noise in oxygenation‐sensitive magnetic resonance imaging
Authors: Krüger Gunnar , Glover Gary H.
Published: October 2004

The physiological noise in the resting brain, which arises from fluctuations in metabolic‐linked brain physiology and subtle brain pulsations, was investigated in six healthy volunteers using oxygenation‐sensitive dual‐echo spiral MRI at 3.0 T. In contrast to the system and thermal noise, the physiological noise demonstrates a signal strength dependency and, unique to the metabolic‐linked noise, an echo‐time dependency. Variations of the MR signal strength by changing the flip angle and echo time allowed separation of the different noise components and revealed that the physiological noise at 3.0 T (1) exceeds other noise sources and (2) is significantly greater in cortical gray matter than in white matter regions. The SNR in oxygenation‐sensitive MRI is predicted to saturate at higher fields, suggesting that noise measurements of the resting brain at 3.0 T and higher may provide a sensitive probe of functional information. Magn Reson Med 46:631–637, 2001. © 2001 Wiley‐Liss, Inc.
4D deformation modeling of cortical disease progression in Alzheimer's dementia
Authors: Janke Andrew L. , Zubicaray Greig de , Rose Stephen E. , Griffin Mark , Chalk Jonathan B. , Galloway Graham J.
Published: October 2004

This work describes the development of a model of cerebral atrophic changes associated with the progression of Alzheimer's disease (AD). Linear registration, region‐of‐interest analysis, and voxel‐based morphometry methods have all been employed to elucidate the changes observed at discrete intervals during a disease process. In addition to describing the nature of the changes, modeling disease‐related changes via deformations can also provide information on temporal characteristics. In order to continuously model changes associated with AD, deformation maps from 21 patients were averaged across a novelz‐score disease progression dimension based on Mini Mental State Examination (MMSE) scores. The resulting deformation maps are presented via three metrics: local volume loss (atrophy), volume (CSF) increase, and translation (interpreted as representing collapse of cortical structures). Inspection of the maps revealed significant perturbations in the deformation fields corresponding to the entorhinal cortex (EC) and hippocampus, orbitofrontal and parietal cortex, and regions surrounding the sulci and ventricular spaces, with earlier changes predominantly lateralized to the left hemisphere. These changes are consistent with results from post‐mortem studies of AD. Magn Reson Med 46:661–666, 2001. © 2001 Wiley‐Liss, Inc.
Quantitative proton MR spectroscopic imaging of normal human cerebellum and brain stem
Authors: Jacobs Michael A. , Horská Alena , van Zijl Peter C.M. , Barker Peter B.
Published: October 2004

Quantitative, multislice proton MR spectroscopic imaging (MRSI) was used to investigate regional metabolite levels and ratios in the normal adult human posterior fossa. Six normal volunteers (36 ± 3 years, five male, one female) were scanned on a 1.5 T scanner using multislice MRSI at long echo time (TE 280 msec). The entire cerebellum was covered using three oblique‐axial slice locations, which also included the pons, mid‐brain, insular cortex, and parieto‐occipital lobe. Concentrations of N‐acetylaspartate (NAA), choline (Cho), and creatine (Cr) were estimated using the phantom replacement technique. Regional variations of the concentrations were assessed using ANOVA (P < 0.05). High‐resolution MRSI data was obtained in all subjects and brain regions examined. Metabolite concentrations (mM) (mean ± SD) were as follows: cerebellar vermis: 2.3 ± 0.4, 8.8 ± 1.7 and 7.6 ± 1.0 for Cho, Cr, and NAA respectively; cerebellar hemisphere: 2.2 ± 0.6, 8.9 ± 2.1, 7.5 ± 0.8; pons 2.2 ± 0.5, 4.3 ± 1.1, 8.3 ± 0.9; insular cortex, 1.8 ± 0.5, 7.8 ± 2, 8.0 ± 1.1, parieto‐occipital gray matter, 1.3 ± 0.3, 5.7 ± 1.1, 7.2 ± 0.9, and occipital white matter, 1.4 ± 0.3, 5.3 ± 1.3, 7.5 ± 0.8. Consistent with previous reports, significantly higher levels of Cr were found in the cerebellum compared to parieto‐occipital gray and occipital white matter, and pons (P < 0.0001). NAA was essentially uniformly distributed within the regions chosen for analysis, with the highest level in the pons (P < 0.04). Cho was significantly higher in the cerebellum and pons than parieto‐occipital gray and occipital white matter (P < 0.002) and was also higher in the pons than in the insular cortex (P < 0.05). Quantitative multislice MRSI of the posterior fossa is feasible and significant regional differences in metabolite concentrations were found. Magn Reson Med 46:699–705, 2001. © 2001 Wiley‐Liss, Inc.
Observed BOLD effects on cerebral metabolite resonances in human visual cortex during visual stimulation: A functional 1H MRS study at 4 T
Authors: Zhu Xiao‐Hong , Chen Wei
Published: October 2004

Using the localized spin‐echo 1H MRS technique, the water resonance and methyl resonance peaks of the cerebral metabolites N‐acetylaspartate (NAA at 2.0 ppm) and phosphocreatine/creatine (Cr at 3.0 ppm) were studied in the human visual cortex to detect and quantify the blood oxygenation level dependent (BOLD) effect during visual stimulation at 4 T. Significant BOLD effects, which reflect the increases of spectral peak height (H) accompanied by the decreases of spectral linewidth (Δυ1/2), were observed in NAA (H: 2.5%; Δυ1/2: −1.7%) and Cr (H: 3.1%; Δυ1/2: −1.8%) as well as in water (H: 3.1%; Δυ1/2: −2.3%). Because NAA and Cr mainly exist in the brain cells, the BOLD effects on these cerebral metabolite resonances only measure the susceptibility component spreading into the extravascular cellular compartment. In contrast, water is affected in the intra‐ and the extravascular compartments. Therefore, the water signal measures the BOLD effects in both compartments. BOLD responses in water were similar to those observed in metabolites. The similarity indicates that the susceptibility spreading into the extravascular parenchyma contributed significantly to the observed BOLD effects at 4 T. Finally, taking advantage of the higher NMR sensitivity at 4 T, the feasibility of measuring BOLD effects on cerebral metabolites by localized 1H MRS is demonstrated. Magn Reson Med 46:841–847, 2001. © 2001 Wiley‐Liss, Inc.
Manganese‐enhanced MRI of mouse heart during changes in inotropy†
Authors: Hu Tom C.‐C. , Pautler Robia G. , MacGowan Guy A. , Koretsky Alan P.
Published: October 2004

Recently the dual properties of manganese ion (Mn2+) as an MRI contrast agent and a calcium analogue to enter excitable cells has been used to mark specific cells in brain and as a potential intracellular cardiac contrast agent. Here the hypothesis that in vivo manganese‐enhanced MRI (MEMRI) can detect changes in inotropy in the mouse heart has been tested. T1‐weighted images were acquired every minute during an experimental time course of 75 min. Varying doses of Mn2+ (3.3–14.0 nmoles/min/g BW) were infused during control and altered inotropy with dobutamine (positive inotropy due to increased calcium influx) and the calcium channel blocker diltiazem (negative inotropy). Infusion of MnCl2 led to a significant increase in signal enhancement in mouse heart that saturated above 3.3 ± 0.1 nmoles/min/g BW Mn2+ infusion. At the highest Mn2+ dose infused there was a 41–47% increase in signal intensity with no alteration in cardiac function as measured by MRI‐determined ejection fractions. Dobutamine increased both the steady‐state level of enhancement and the rate of MRI signal enhancement. Diltiazem decreased both the steady‐state level of enhancement and the rate of MRI signal enhancement. These results are consistent with the model that Mn2+‐induced enhancement of cardiac signal is indicative of the rate of calcium influx into the heart. Thus, the simultaneous measurement of global function and calcium influx using MEMRI may provide a useful method of evaluating in vivo responses to inotropic therapy. Magn Reson Med 46:884–890, 2001. Published 2001 Wiley‐Liss, Inc.
Water and lipid MRI of the Xenopus oocyte
Authors: Sehy Jonathan V. , Ackerman Joseph J.H. , Neil Jeffrey J.
Published: October 2004

Oocytes of Xenopus laevis are large, single cells that provide a promising model system for the exploration of the MR biophysics fundamental to more complex living systems. Previous studies have generally employed 2D spin‐echo sequences with an image slice thickness greater than the thickness of the cellular volumes of interest. Also, the large cytoplasmic lipid signal has typically been ignored. This study describes separate, high‐resolution 3D measurements of the water and lipid spin densities, T1 and T2 relaxation time constants, and the water apparent diffusion rate constant (ADC) in the Xenopus oocyte without significant partial volume artifacts. The lipid spin‐density and values for water MR properties varied monotonically from the vegetal to animal poles, indicating that the border between the poles is not sharply demarcated. Regional water MR property values correlated with lipid signal intensity. Lipid‐specific imaging is shown for which water suppression is achieved via high diffusion weighting in the imaging sequence. Magn Reson Med 46:900–906, 2001. © 2001 Wiley‐Liss, Inc.
Magnetic susceptibility quantification for arbitrarily shaped objects in inhomogeneous fields
Authors: Li Lin
Published: October 2004

Magnetic susceptibility measurement has wide‐ranging applications in MR technical development and medical applications. A general susceptibility quantitation method for objects of arbitrary shapes in inhomogeneous magnetic fields is presented in this study. Based on the mean value properties of magnetic fields, the polarizing magnetic field at the location of interest inside an object can be exactly obtained in situ from the field values on a spherical surface enclosing the object. With numerical computation of the self‐demagnetizing field and correction of contact shifts, magnetic susceptibilities were quantitatively measured for CuSO4 phantoms based on their MR gradient echo phase maps. Magn Reson Med 46:907–916, 2001. © 2001 Wiley‐Liss, Inc.
Molecular factors that determine Curie spin relaxation in dysprosium complexes†
Authors: Caravan P. , Greenfield M.T. , Bulte J.W.M.
Published: October 2004

Dysprosium complexes can serve as transverse relaxation (T2) agents for water protons through chemical exchange and the Curie spin relaxation mechanism. Using a pair of matched dysprosium(III) complexes, Dy‐L1 (contains one inner‐sphere water) and Dy‐L2 (no inner‐sphere water), it is shown that the transverse relaxation of bulk water is predominantly an inner‐sphere effect. The kinetics of water exchange at Dy‐L1 were determined by 17O NMR. Proton transverse relaxation by Dy‐L1 at high fields is governed primarily through a large chemical shift difference between free and bound water. Dy‐L1 forms a noncovalent adduct with human serum albumin which dramatically lengthens the rotational correlation time, τR, causing the dipole–dipole component of the Curie spin mechanism to become significant and transverse relaxivity to increase by 3–8 times that of the unbound chelate. These findings aid in the design of new molecular species as efficient r2 agents. Magn Reson Med 46:917–922, 2001. Published 2001 Wiley‐Liss, Inc.
Ex vivo MR microimaging of neuronal damage after kainate‐induced status epilepticus in rat: Correlation with quantitative histology
Authors: Pirttilä Tiina‐Riikka M. , Pitkänen Asla , Tuunanen Jarkko , Kauppinen Risto A.
Published: October 2004

The present study was designed to investigate whether T2‐weighted signal changes obtained by microimaging of paraformaldehyde‐fixed brain correlate with the histologically quantified damage in a model of status epilepticus (SE) induced by kainic acid in the rat. Animals were killed at several time points up to 8 weeks after a single intraperitoneal kainate (KA) injection (9 mg/kg). Perfusion‐fixed brains were embedded in gelatin for MR microimaging at 9.4T. After the MRI analysis, the gelatin was removed and the brains were cryoprotected and processed for quantitative histology. Severity of neuronal damage and gliosis were assessed from thionin‐stained serial sections. Correlative analysis of microimaging and histology data was done in the hippocampus, amygdala, parietal rhinal cortex (PaRH), piriform cortex (Pir), and entorhinal cortex. The relative signal intensities in T2‐weighted images correlate with the severity of neuronal damage in the matched histological sections (correlation coefficients of 0.752–0.826). Our data show that MR microimaging ex vivo detects the degree of neuronal damage and its anatomical distribution after KA‐induced SE, thus providing a useful tool for detecting the dynamics of progressive neuronal damage after prolonged seizures. Magn Reson Med 46:946–954, 2001. © 2001 Wiley‐Liss, Inc.
High‐resolution intracranial and cervical MRA at 3.0T: Technical considerations and initial experience
Authors: Bernstein Matt A. , Huston John , Lin Chen , Gibbs Gordon F. , Felmlee Joel P.
Published: October 2004

Initial experience with intracranial and cervical MRA at 3.0T is reported. Phantom measurements (corrected for relaxation effects) show S/N (3.0T) = 2.14 ± 0.08 × S/N (1.5T) in identical‐geometry head coils. A 3.0T 3DTOF intracranial imaging protocol with higher‐order autoshimming was developed and compared to 1.5T 3DTOF in 12 patients with aneurysms. A comparison by two radiologists showed the 3.0T to be significantly better (P < 0.001) for visualization of the aneurysms. The feasibility of cervical and intracranial contrast enhanced MR angiography (CEMRA) at 3.0T is also examined. The relaxivity of the gadolinium contrast agent decreases by only about 4–7% when the field strength is increased from 1.5 to 3.0T. Cervical 3.0T CEMRA was obtained in eight patients, two of whom had 1.5T studies available for direct comparison. Image comparison suggests 3.0T to be a favorable field strength for cervical CEMRA. Voxel volumes of 0.62–0.73 mm3 (not including zero‐filling) were readily achieved at 3.0T with the use of a single‐channel transmit‐receive head or cervical coil, a 25 mL bolus of gadoteridol, and a 3D pulse sequence with a 66% sampling efficiency. This spatial resolution allowed visualization of intracranial aneurysms, carotid dissections, and atherosclerotic disease including ulcerations. Potential drawbacks of 3.0T MRA are increased SAR and T dephasing compared to 1.5T. Image comparison suggests signal loss due to T dephasing will not be substantially more problematic than at 1.5T. The dependence of RF power deposition on TR for CEMRA is calculated and discussed. Magn Reson Med 46:955–962, 2001. © 2001 Wiley‐Liss, Inc.
Arterial spin labeling in combination with a look‐locker sampling strategy: Inflow turbo‐sampling EPI‐FAIR (ITS‐FAIR)
Authors: Günther Matthias , Bock Michael , Schad Lothar R.
Published: October 2004

Arterial spin labeling (ASL) permits quantification of tissue perfusion without the use of MR contrast agents. With standard ASL techniques such as flow‐sensitive alternating inversion recovery (FAIR) the signal from arterial blood is measured at a fixed inversion delay after magnetic labeling. As no image information is sampled during this delay, FAIR measurements are inefficient and time‐consuming. In this work the FAIR preparation was combined with a Look‐Locker acquisition to sample not one but a series of images after each labeling pulse. This new method allows monitoring of the temporal dynamics of blood inflow. To quantify perfusion, a theoretical model for the signal dynamics during the Look‐Locker readout was developed and applied. Also, the imaging parameters of the new ITS‐FAIR technique were optimized using an expression for the variance of the calculated perfusion. For the given scanner hardware the parameters were: temporal resolution 100 ms, 23 images, flip‐angle 25.4°. In a normal volunteer experiment with these parameters an average perfusion value of 48.2 ± 12.1 ml/100 g/min was measured in the brain. With the ability to obtain ITS‐FAIR time series with high temporal resolution arterial transit times in the range of −138 − 1054 ms were measured, where nonphysical negative values were found in voxels containing large vessels. Magn Reson Med 46:974–984, 2001. © 2001 Wiley‐Liss, Inc.
Temperature mapping of frozen tissue using eddy current compensated half excitation RF pulses
Authors: Wansapura Janaka P. , Daniel Bruce L. , Pauly John , Butts Kim
Published: October 2004

Cryosurgery has been shown to be an effective therapy for prostate cancer. Temperature monitoring throughout the cryosurgical iceball could dramatically improve efficacy, since end temperatures of at least –40°C are required. The results of this study indicate that MR thermometry based on tissue R has the potential to provide this information. Frozen tissue appears as a complete signal void on conventional MRI. Ultrashort echo times (TEs), achievable with half pulse excitation and a short spiral readout, allow frozen tissue to be imaged and MR characteristics to be measured. However, half pulse excitation is highly sensitive to eddy current distortions of the slice‐select gradient. In this work, the effects of eddy currents on the half pulse technique are characterized and methods to overcome these effects are developed. The methods include: 1) eddy current compensated slice‐select gradients, and 2) a correction for the phase shift between the first and second half excitations at the center of the slice. The effectiveness of these methods is demonstrated in R maps calculated within the frozen region during cryoablation. Magn Reson Med 46:985–992, 2001. © 2001 Wiley‐Liss, Inc.
Pulmonary MR angiography with contrast agent at 4 Tesla: A preliminary result
Authors: Uematsu Hidemasa , Dougherty Lawrence , Takahashi Masaya , Ohno Yoshiharu , Nakatsu Masashi , Song Hee Kwon , Ferrari Victor A. , Gefter Warren B. , Schnall Mitchell D. , Hatabu Hiroto
Published: October 2004

In this study, pulmonary MR angiography (MRA) using a tailored coil at 4 Tesla in conjunction with an intravenous injection of contrast agent is described. Three‐dimensional gradient‐echo images were obtained during the intravenous injection of 0.05, 0.1, and 0.2 mmol/kg body weight of gadodiamide to investigate the signal enhancement effect of the contrast agent in pulmonary arteries qualitatively and quantitatively. In the qualitative analysis, the subsegmental branches were visualized on every dose. In the quantitative analysis, the average contrast‐to‐noise ratios (CNRs) of the main pulmonary arteries increased in a dose‐dependent manner. However, the CNRs of segmental arteries did not increase as the dose of contrast agent increased, as observed at 1.5 Tesla MRI. These observations demonstrate the feasibility of delineating the pulmonary vasculature using a contrast agent; however, our results also suggest possible high‐field‐related disabilities that need to be overcome before high‐field (≥4 Tesla) MRI can be used to full advantage. Magn Reson Med 46:1028–1030, 2001. © 2001 Wiley‐Liss, Inc.
Tracking local volume 3D‐echo‐planar coronary artery imaging
Authors: Gatehouse P.D. , Keegan J. , Yang G.Z. , Mohiaddin R.H. , Firmin D.N.
Published: October 2004

Aiming for robust high‐resolution free respiration coronary artery imaging, localized tracking volume selective 3D‐EPI at spatial resolution 1.25 × 1.25 × 3 mm and temporal resolution 65 ms was evaluated in 14 normal subjects. Subject‐specific motion tracking factors were measured between diaphragm navigator and coronary artery in S‐I and A‐P directions. Imaging was repeated with and without tracking, accepting 128 cardiac cycles over a 20‐mm range from free breathing. Reference images with minimal respiratory motion (5‐mm range) used LED‐guided multiple breathholds. Depending on accurate motion measurement, coronary arteries were imaged with tracking, in a 20‐mm range of free breathing, with increased scan efficiency but without significant loss of image quality compared to multiple breathhold imaging. Magn Reson Med 46:1031–1036, 2001. © 2001 Wiley‐Liss, Inc.
MR angiography using spin‐lock flow tagging
Authors: Azhari Haim , McKenzie Charles A. , Edelman Robert R.
Published: October 2004

A method for MR angiography using an RF labeling technique is suggested. The method utilizes a slice‐selective spin‐lock pulse sequence for tagging the spins of inflowing blood. The pulse sequence begins with a spatially selective 90°x RF pulse, followed by a nonselective composite locking pulse of 135°y − n[360°y]‐135°y and by a 90°‐x pulse. A spoiler gradient is then applied. A rapid imaging stage, which yields a T1ρ‐weighted signal from the tagged spins, completes the sequence. Untagged spins are thoroughly dephased and consequently suppressed in the image. Thus, contrast is obtained without an injection of a contrast material or image subtraction. Furthermore, the flow of the tagged bolus can be visualized. The sequence was implemented on phantoms and on human volunteers using a 1.5T scanner. The results indicate the feasibility of the suggested sequence. Magn Reson Med 46:1041–1044, 2001. © 2001 Wiley‐Liss, Inc.
Patterns in spatial point locations: Local indicators of spatial association in a minefield with clutter
Authors: Cressie Noel , Collins Linda Brant
Published: October 2004

The problem of detecting a minefield in the presence of clutter can be abstracted to that of detecting a spatial pattern within a set of point locations. The point locations are superpositions of several patterns, one of which corresponds to mines. In contrast to previous articles that take a formal, model‐based approach, this article proposes a statistical methodology that is distinctly exploratory. Each point location is considered separately, and its contributions to a global measure of spatial distances between locations are featured. Different patterns and unusual points can be more easily identified on the new scale. Both minefield data and simulated point patterns demonstrate the power of the method. © 2001 John Wiley & Sons, Inc., Naval Research Logistics 48:333–347, 2001
An application of yield management for Internet Service Providers
Authors: Nair Suresh K. , Bapna Ravi
Published: October 2004

In this paper we study strategies for better utilizing the network capacity of Internet Service Providers (ISPs) when they are faced with stochastic and dynamic arrivals and departures of customers attempting to log‐on or log‐off, respectively. We propose a method in which, depending on the number of modems available, and the arrival and departure rates of different classes of customers, a decision is made whether to accept or reject a log‐on request. The problem is formulated as a continuous time Markov Decision Process for which optimal policies can be readily derived using techniques such as value iteration. This decision maximizes the discounted value to ISPs while improving service levels for higher class customers. The methodology is similar to yield management techniques successfully used in airlines, hotels, etc. However, there are sufficient differences, such as no predefined time horizon or reservations, that make this model interesting to pursue and challenging. This work was completed in collaboration with one of the largest ISPs in Connecticut. The problem is topical, and approaches such as those proposed here are sought by users. © 2001 John Wiley & Sons, Inc., Naval Research Logistics 48:348–362, 2001
The NBUL class of life distribution and replacement policy comparisons
Authors: Yue Dequan , Cao Jinhua
Published: October 2004

Let X and Xτ denote the lifetime and the residual life at age τ of a system, respectively. X is said to be a NBUL random variable if Xτ is smaller than X in Laplace order, i.e., Xτ ≤L X. We obtain some characterizations for this class of life distribution by means of the lifetime of a series system and the residual life at random time. We also discuss preservation properties for this class of life distribution under shock models. Finally, under the assumption that the lifetimes have the NBUL property, we make stochastic comparisons between some basic replacement policies. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 578–591, 2001.