bluuebunny/crossref_metadata_2025_split huggingface dataset:
Csf‐suppressed t2‐weighted threel‐dimensional mp‐rage MR imaging
Authors: Epstein Frederick H. , Mugler John P. , Cail Wayne S. , Brookeman James R. 
Published: March 2007

AbstractFluid‐attenuated inversion recovery (FLAIR) is a pulse sequence used for acquiring T2‐weighted images of the brain and spine in which the normally high signal intensity of CSF is greatly attenuated. The CSF‐sup pressed T2‐weighted contrast of this technique may be more sensitive to a variety of disorders than that of conventional Tz‐weighted imaging. The primary disadvantage associated with conventional spin‐echo implementations of FLAIR is the relatively limited anatomic coverage that can be achieved in a reasonable imaging time. We developed and optimized a three‐dimensional magnetization‐prepared rapid gradient‐echo (3D MP‐RAGE) pulse sequence that combines CSF‐suppressed T2‐weighted contrast similar to exleting FLAIR techniques with anatomic coverage characteristic of 3D imaging. A preliminary evaluation of the new sequence was performed by imaging healthy volunteers and patients with multiple sclerosis.
Clearance of gadolinium chelates by hemodialysis: An in vitro study
Authors: Choyke Peter L. , Girton Mary E. , Frank Joseph A. , Vaughan Ellen M. , Austin Howard A. 
Published: March 2007

AbstractAlthough the gadolinium (Gd)‐chelates currently approved for clinical use in the United States are considered “readily dialyzable,” the actual clearance rates have not been published. The purpose of this study was to establish in vitro dialysis clearance rates of Gd‐chelates to develop rational strategies for removing the agents with dialysis. Three agents, Gd‐diethylenetriaminopentaacetic acid (Gd‐DTPA), Gd‐HP‐DO3A and Gd‐DTPA‐BMA were diluted separately in plasma and saline and were dialyzed by using a clinical dialyzer unit with a commercially available capillary filter at rates of 0‐300 cc/min. Predialyzer and postdialyzer concentrations were determined by inductively coupled atomic emission photometry. Urea and creatinine clearance rates also were determined.The clearance rate for Gd‐chelates were considerably lower than that of urea and cnatinine, which are generally considered benchmarks of dialysis efficiency. At 300 cc/min flow rates, the clearances were (clearance in cubic centimeters per minute with 95% con5dence interval): Gd‐DTPA‐74 cc/min (68‐80 cc/ a) S‐HP‐DO3A 67 cc/min (63‐71cc/min); and Gd‐ DTPA‐BMA 67 cc/min (63‐7lcc/min). In comparison, urea and creatinine were 180 cc/min (178‐181 cc/ mh) and 142 cc/& (124131 cc/min). respectively. There was no difference between clearance rates of Gd‐chelates in saline and plasma. implying there was no protein binding. By using a first order kinetic model of dialysis time, more than 12.2 to 14.7 hours of dialysis would be necessary to remove 97% of the injected dose of Gd‐chelate. In conclusion, Gd‐chelates are dialyzable and 97% elimination is predicted after 12‐14.7 hours of dialysis, depending on the chelate used. Consequently, Gd‐based contrast agents can be used in dialysis patients without modification to most maintenance dialysis schedules.
Phased‐Array Magnetic Resonance Imaging of the Carotid Artery Bifurcation: Preliminary Results in Healthy Volunteers and a Patient with Aherosclerotic Disease
Authors: Yuan Chun , Murakami James W. , Hayes Cecil E. , Tsuruda Jay S. , Hatsukami Thomas S. , Wildy Kathryn S. , Ferguson Marina S. , Strandness D. Eugene 
Published: March 2007

AbstractA high resolution MR Imaging technique using a amtom designed flexible phased‐array surface coil was developed to examine the wall of the carotid artery bifuraction in vivo. The phaecd‐array consisted of two overlapping coils which increased the image signal‐to‐noise ratio at the depth of the carotid artery by approximately 70%, relative to a similarly sized single loop coil. The imaging protocol included a 2D T1‐weighted (TIW) spin‐echo scan and cardiac gated T2‐weighted and proton density‐weighted (PDW) fast Spin‐echo (FSE) scans. Images where obtained of six healthy volunteers and of one patient with known atherosclerotic dirreaw several days before carotid endartuectomy. On TIW and PDW images of the healthy volunteers. the carotid arterial wall appeared to be comprised of two concentric rings; a high signal inner ring and a lower signal outer ring. The MR images of the patient revealed a calcified carotid bifurcation plaque which was confirmed during surgery. The endarterectomy specimen WM imaged in vitro with MR and then sectioned histologically for correlation with the patients in vivo images. Our preliminary findings indicate that a high resolution technique may provide a noninvasive technique to study atherosclerosis of the carotid bifurcation.
A velocity correlation method for measuring vascular compliance using MR imaging
Authors: Urchuk Stephen N. , Plewes Donald B. 
Published: March 2007

AbstractA method for estimating vascular compliance using MR velocity imaging is presented. The technique combines an analysis of pulse propagation, based on spatially averaged equations of continuity and momentum, together with phase‐contrast velocity measurements to estimate the compliance from a correlation of second‐order spatial and temporal velocity derivatives. The technique can be applied in the presence of reflected flow waves and uses velocity data acquired throughout the entire cardiac cycle. The accuracy of the technique was assessed in distensible vessel phantoms spanning a physiological range of compliance through a comparison with compliance estimates obtained using high‐resolution MR imaging and pressure transducers. The mean error of all measurements was found to be 0.04 ±0.02% per mm Hg, with the relative errors ranging from 1.2% to 46%. Error was found to decrease as the temporal sampling rate and/or image plane separation were increased. This suggests that an accurate hemodynamic evaluation of a vessel's elastic properties is feasible with MR velocity imaging techniques.
Plow quantitation with echo‐planar phase‐contrast velocity mapping: In vitro and in vivo evaluation
Authors: Debatin Jorg F. , Leung Daniel A. , Wildermuth Simon , Botnar Rene , Felblinger Jacques , McKinnon Graeme C. 
Published: March 2007

AbstractWe present a multishot echo‐planar imaging (EPI) phase‐contrast implementation for flow quantitation. The measurement accuracy of this technique was evaluated in vitro and in vivo. A gated eight‐shot EPI phase‐contrast sequence (TR/TE = 16/7.4, 45° flip angle), with a flow‐phase interval of 32 msec and an in‐plane resolution of 2× 2 mm was initially evaluated in a pulsatile flow phantom. Subsequently, EPI phase‐contrast flow measurements of the ascending and descending aorta, obtained in 10 volunteers, were compared with flow volume data acquired with a conventional cine phase‐contrast sequence (TR/TE = 24/7, 45° flip angle, 48‐msec flow‐phase interval, 2 × 1 mm in‐plane resolution). Comparisons between flow measurements were made using data obtained with the flow probe and cine phase contrast as the standard of reference for in vitro and in vivo measurements, respectively. EPI phase‐contrast sequences reduced data acquisition times tenfold compared with cine phase‐contrast sequences. EPI phase‐contrast flow measurements correlated were with phantom flow (r = 0.98, slope = 1.1) as well as with aortic cine phase‐contrast flow volume determinations (r = 0.98). A 95% confidence interval of measurement differences between echo‐planar and cine phase‐contrast imaging, ranging from 2.0 to ‐ 1058 mL/min was computed. Ultrafast phase‐contrast flow measurements are possible. Multishot EPI phase‐contrast imaging provides high measurement accuracy in pulsatile vessels while keeping the image acquisition interval short enough to be accomplished in a comfortable breath‐hold.
Comparison of phantom and computer‐simulated MR images of flow in a convergent geometry: Implications for improved two‐dimensional MR angiography
Authors: Siegel John M. , Oshinski John N. , Pettigrew Roderic I. , Ku David N. 
Published: March 2007

AbstractThe signal loss that occurs in regions of disturbed flow significantly decreases the clinical usefulness of MR angiography in the imaging of diseased arteries. This signal loss is most often attributed to turbulent flow; but on a typical MR angiogram, the signal is lost in the nonturbulent upstream region of the stenosis as well as in the turbulent downstream region. In the current study we used a flow phantom with a forward‐facing step geometry to model the upstream region. The flow upstream of the step was convergent, which created high levels of convective acceleration. This region of the flow field contributes to signal loss at the constriction, leading to overestimation of the area of stenosis reduction. A computer program was designed to simulate the image artifacts that would be caused by this geometry in two‐dimensional time‐of‐flight MR angiography. Simulated images were compared with actual phantom images and the flow artifacts were highly correlated. The computer simulation was then used to test the effects of different orders of motion compensation and of fewer pixels per diameter, as would be present in MR angiograms of small arteries. The results indicated that the computational simulation of flow artifacts upstream of the stenosis provides an important tool in the design of optimal imaging sequences for the reduction of signal loss.
Dynamic contrast‐enhanced MR imaging evaluation of osteosarcoma response to neoadjuvant chemotherapy
Authors: Reddick Wilburn E. , Bhargava Ravi , Taylor June S. , Meyer William H. , Fletcher Barry D. 
Published: March 2007

AbstractAssessment of osteosarcoma response to neoadjuvant chemotherapy has prognostic implications, but conventional imaging techniques have been unable to provide an accurate quantitative measure of tumor response. We developed an analysis of dynamic contrast‐enhanced MR imaging (DEMRI) to render an image of dynamic vector magnitudes (DVM) and to summarize the result in a quantitative parameter, mean DVM for the lesion (μDVM). We compared the (μDVM from the examination before surgery with histologic results from an en bloc resection of the tumor in 19 cases. The final μDVM value provided an accurate (89.5%) measure of tumor necrosis in osteosarcoma. Further, we analyzed the findings in 17 patients with osteosarcoma who completed three DEMRI examinations during the course of therapy. Tumors with higher μDVM values at presentation had greater decreases in the parameter over the course of therapy. These results are consistent with the distribution of DVM values in these lesions serving as an indicator of tumor perfusion and a possible surrogate variable for drug delivery.
Mr image‐guided control of cryosurgery
Authors: Pease Grant R. , Wong Sam T. S. , Roos Mark S. , Rubinsky Boris 
Published: March 2007

AbstractCryoablation has recently become a useful procedure for the treatment of prostatic and hepatic tumors, primarily because of advances in the ability to monitor visually the freezing process with ultrasound. Success of the procedure depends in large part on how well the ice front can be positioned to destroy pathologic tissue, while sparing healthy tissue. This study describes a cryogen delivery system that can be used in conjunction with magnetic resonance (MR) image‐guided cryoablation, and an automatic control system that uses MR image guidance in a feedback loop to control the ice front trajectory. Edge‐detected MR images are used to determine the current ice front location at each time interval, providing feedback to an automatic control system that adjusts the flow of cryogen to the cryoprobe. Numerical simulations and experimental results demonstrate that an ice front with cylindrical symmetry can be accurately controlled using this MR image‐guided feedback control scheme.
A variable‐ force microvascular clip
Authors: Dujovny Manuel , Perlin Alfred , Kossovsky Nir 
Published: March 2007

AbstractAn easily adjustable, variable‐ force microvascular clip is described. This clip is superior to other clips currently available because it is essentially three clips in one. Its advantages are that it can reduce the amount of table area needed to store clips during surgery and it offers the surgeon greater flexibility in the selection of clips with different closing forces. This clip was developed by modifying the segments of a basic alpha‐ type clip, designing a computer program to analyze the force contributions made by each segment of the clip, constructing several clips with different blade lengths, and testing them in a microvascular surgery research program. The clip we have developed is easy to use, reduces clutter on the instrument table, and offers the surgeon a wide choice of closing forces with a minimal number of clips.
Arterial anastomoses and autogenous interposition grafts in growing rats
Authors: Stoll Amos W. , Chater Norman , Phillips Mark 
Published: March 2007

AbstractThe fate of arterial interposition grafts in growing rats was investigated. The interrupted‐ and continuous‐suture techniques were compared to see which allowed for better expansion of the anastomosis. We found that a graft enlarges in proportion to the growth of the parent vessel, that in end‐to‐end anastomosis the interrupted suture technique allowed for better expansion of the anastomosis (but not in the end‐to‐side model), and that the continous suture technique was associated with a higher rate of false aneurysm formation.
Empty perineurial tube graft used to repair a digital nerve: A first case report
Authors: Restrepo Yolanda , Merle Michel , Petry Didier , Michon Jacques 
Published: March 2007

AbstractThe first clinical application using the medial cutaneous nerve as an empty perineurial tube graft in a patient with sensory deficit in the index finger is described. The technique used is described and results are evaluated both qualitatively and quantitatively. Nerve regeneration is obtained through the graft.
Effect of sympathectomy on microvascular anastomosis in the rat
Authors: Hweidi Sobhi A. , Lee Sun , Wolf Paul 
Published: March 2007

AbstractAn operative technique of lumbar sympathectomy in the rat is described. Two days following either sympathectomy or sham‐sympathectomy, bilateral femoral arterial anastomoses were performed by a 1‐year trained microsurgeon (S.A.H.) and patency was assessed by preoperative and postoperative (30 minutes, daily) operative invasive and noninvasive techniques using an electromagnetic flow meter (for immediate postoperative) and Doppler, respectively. Of 112 rats, three and one postoperative deaths occurred within 24 hours following abdominal surgery in each group, respectively. Of 105 anastomoses in the sympathectomy group, 103 (98%) and 101 (96%) had patent anastomoses 30 minutes and 14 days postoperatively, respectively, while 109 of the sham‐sympathectomy group had 105 (96%) and 103 (94%) patencies at the same period of the observation, respectively. Thus the sympathectomy did not much alter the microvascular patency rate in the rat. It appears therefore that the meticulous microvascular anastomosis cannot be replaced by lumbar sympathectomy in the rat.
Debridement and replantation of the spleen with microsurgical restoration of blood flow
Authors: Monsivais J. , Seaber Anthony , Urbaniak James R. 
Published: March 2007

AbstractSplenectomy continues to be the most commonly chosen method of management of traumatic injury to the spleen. However, patients of all age groups who have undergone splenectomy have significant impairment of immune functions as demonstrated by decreased production of IGM, tufsin, and properdin. This immune deficiency has been clinically manifested by an increased incidence of postsplenectomy pneumonia and sepsis which is reduced but not eliminated by the use of pneumococcal vaccine and/or prophylactic antibiotics. This paper presents the results of a study of the feasibility of repair and replantation of injured spleens using microsurgical techniques. Twenty cats had their spleens removed, finger‐fractured, and debrided. The cats were then assigned to one of four groups. Group I had the entire spleen replanted but only 75% of the parenchyma revascularized. Group II had 75% of the parenchyma revascularized and replanted. Group III had 50% revascularized and replanted, and Group IV 25% revascularized and replanted. Patency of the anastomoses was assessed by postoperative arteriography. Restoration of reticuloendothelial (filter) function was assessed by the use of technetium sulphur colloid scans which showed preservation of reticuloendothelial function of the revascularized segments but absence of function in nonrevascularized segments which had been replanted. Histologic examination of replanted spleens harvested at 8 weeks showed normal architecture of red and white pulp in all areas that had been revascularized. However, in those spleens where the entire spleen had been replanted but only partially revascularized, the nonrevascularized segments were degenerated and atrophic.
A microsurgical method for experimental kidney denervation
Authors: Kullendorff Carl Magnus 
Published: March 2007

AbstractA successful microsurgical method for denervation of the kidney in the rat is presented. Unilateral kidney denervation was performed in eight animals. Ten sham‐operated animals were used as controls. Under ether anaesthesia, the kidney vessels on one side were exposed. The peritoneum above the vessels was incised and the area was stained with 1% toluidine blue solution. The nerves were identified. With microsurgical technique, the nerves were carefully separated from the vessels and resected. Tissue specimens from both kidneys in all animals were removed and analysed for norepinephrine content. There was no normal difference between the kidneys in the shamoperated rats. About 1 week after denervation, the norepinephrine concentration in the denervated kidney showed a 95% reduction, indicating a complete denervation. The described microsurgical procedure was a rapid, simple, and reproducible method for kidney denervation in the rat.
Intimal tears and their relationship to longterm patency in the rat femoral artery
Authors: Glover Michael G. , Seaber Anthony V. , Urbaniak James R. 
Published: March 2007

AbstractThe prognostic importance of arterial intimal tears is not certain in the long term. We have developed a model to evaluate pure intimal damage in the absence of other soft tissue injury or arterial anastomoses to study the effect of isolated traumatic arterial intimal tears. Groups of ten rats each were examined at 1, 2, 4, 8, and 48 weeks and were shown to have no incidence of thrombosis of the femoral artery following traumatic intimal tears. Histologically, there was persistence of medial disorganization and smooth muscle hypertrophy up to 48 weeks. We feel that intimal lesions alone do not predispose a rat femoral artery to thrombosis but might do so in the presence of significant soft tissue injury or an arterial anastomosis.
New method for cardiac transplantation
Authors: Umeki Yasuhiro , Weinrib Harry P. , MacLeod Cathel A. , Economou Steven G. , Gebel Howard M. 
Published: March 2007

AbstractRat cardiac transplantation into the femoral region has several advantages compared to cardiac transplantation into the peritoneal cavity. These advantages include increased speed, decreased hypothermia of the recipient, and easier‐access palpation. However, there is a major discrepancy in the size of the donor and recipient vessels. The donor aorta is two to three times larger than the recipient's femoral artery and thus could be a contraindication to the transplant. To circumvent this problem, we anastomosed the donor's aorta with the recipient's femoral artery by an end‐in‐end technique whereas the donor's pulmonary artery was anastomosed by conventional end‐to‐end technique with the recipient's femoral vein. The excess wall of the donor's vessel was plicated on a slant for each anastomosis. Our results compare favorably to those of techniques established previously. We suggest that this new method of cardiac transplantation will be of great value in the study of immunological events involved in graft rejection.
Mural repair following obliteration of aneurysms: II. Pathomorphology of treated aneurysms
Authors: Young Paul H. , Fischer Vernon W. , Young Paul A. , Guity Afrassiab , El Fiki Mohammed 
Published: March 2007

AbstractMural vascular repair following experimental and clinical aneurysm obliteration was studied using the scanning electron microscope and standard histological techniques. Two of the more frequently utilized clinical obliteration techniques, clipping and coagulation, were examined. A chronological description of the mural reparative process reveals that clipping is superior to coagulation in most instances, that coagulation results in satisfactory obliteration of the aneurysmal orifice only in very selected circumstances, and that a combination of coagulation and clipping may be the best overall obliteration technique.
Long‐term studies of pancreas allotransplantation in experimental diabetes mellitus
Authors: Lee Sun , Scott Michael H. , Yancey Diane , Allen Jennifer , Chang Eil Sung , Chisari Francis , Moossa A. R. 
Published: March 2007

AbstractPancreaticoduodenal (PD) allografts (Brown Noway‐alloxan‐diabetic rats, n = 190) were treated with cyclosporin A (Cy‐A) 10 mg/kg/daily and compared with nondiabetics with Cy‐A treatment (n = 55), diabetics (n = 50), and diabetics with Cy‐A treatment (n = 45). Body weight, blood sugar, blood insulin, blood urea nitrogen (BUN), and creatinine were monitored periodically; there were marked elevations of BUN and creatinine levels, indicating probable nephrotoxicity of Cy‐A at this dosage. Some islet cell atrophy in the PD allografts was noted at the conclusion of the study. With respect to the immunosuppressive effect of Cy‐A in alloxan diabetic rats, Brown Norway PD transplants into Lewis rats were successful and free of rejection for as long as 15 months post‐transplantation. The body weight of these PD transplanted rats, however, never approached values representative of the nondiabetic rats. In our experience, the PD allograft model is acceptable in the clinical situation, particularly in children if the microsurgical technique is mastered and if the Cy‐A regimen is used in combination with other immunosuppressant(s).
Microlaryngology: An update on its modern use in laryngology‐malignant early and advanced glottic carcinoma
Authors: Hickscol Julius N. 
Published: March 2007

AbstractThe modern use of microlaryngology is improving the diagnosis and treatment of early and advanced glottic laryngeal lesions. Microlaryngology is a microscopic laryngoscopic technique that is used to carry out laryngeal tumor evaluation and biopsy. For early, small, and advanced laryngeal glottic lesions, a microscope is used to view the larynx through a laryngoscope that is placed transorally. This is a precise method of microsurgery to biopsy and stage early and advanced malignant tumors of the glottic area of the larynx. Recent advances using microscopic visualization, microsurgical instruments, and a CO2 laser as a tool to control bleeding and to debulk the tumors of patients with advanced lesions enable the operating surgeon to visualize accurately the involvement by tumor of the overlying mucosa or the underlying muscles and cartilages in this area and sometimes to restore the airway. Precise knowledge regarding the microscopic locational extent of these tumors is important in developing appropriate options for treatment of early and advanced malignant neoplasms of the glottic area of the larynx in order to cure the disease and save the voice of the patient.