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PubMed1990

Binding of the bovine basic pancreatic trypsin inhibitor (Kunitz) to the 33,000 Mr and 54,000 Mr species of human urokinase: thermodynamic study.

The effect of pH and temperature on the apparent association equilibrium constant (Ka) for the binding of the bovine basic pancreatic trypsin inhibitor (BPTI, Kunitz inhibitor) to the 33,000 Mr and 54,000 Mr species of human urokinase (EC 3.4.21.31) has been investigated. Under all the experimental conditions, values of Ka for BPTI binding to the 33,000 Mr and 54,000 Mr species of human urokinase are identical. On lowering the pH from 9.5 to 4.5, values of Ka (at 21.0 degrees C) for BPTI binding to human urokinase (33,000 Mr and 54,000 Mr species) decrease thus reflecting the acidic pK-shift of the His-57 catalytic residue from 6.9, in the free enzyme, to 5.1, in the proteinase:inhibitor complex. At pH 8.0, values of the apparent thermodynamic parameters for BPTI binding to human urokinase (33,000 Mr and 54,000 Mr species) are: Ka = 4.9 x 10(4) M-1, delta G degree = -6.3 kcal/mol, and delta S degree = -37 entropy units (all at 21.0 degrees C); and delta H degree = +4.6 kcal/mol (temperature independent over the explored range, from 5.0 degrees C to 45.0 degrees C). Thermodynamics of BPTI binding to human urokinase (33,000 Mr and 54,000 Mr species) have been analyzed in parallel with those of related serine (pro)enzyme Kazal- and /Kunitz-type inhibitor systems. Considering the known molecular models, the observed binding behaviour of BPTI to human urokinase (33,000 Mr and 54,000 Mr species) was related to the inferred stereochemistry of the proteinase/inhibitor contact region.

Animals↗
PubMed2005

MR microscopy of the parotid glands in patients with Sjogren's syndrome: quantitative MR diagnostic criteria.

BACKGROUND AND PURPOSE: MR imaging of the salivary glands has been applied to the diagnosis of Sjogren's syndrome; however, the diagnosis remains qualitative. We sought to establish and evaluate quantitative MR imaging criteria for the diagnosis of Sjogren's syndrome. METHODS: MR imaging with a 47-mm microscopy coil was performed in 83 patients with xerostomia (55 patients with Sjogren's syndrome, 28 without Sjogren's syndrome). MR images were obtained by T1-weighted and fat-suppressed T2-weighted imaging and by MR sialography of the parotid glands. MR imaging findings of the parotid glands in Sjogren's syndome included increases in fat areas and decreases in intact lobule areas. These MR images were morphometrically analyzed for the diagnostic criteria. RESULTS: MR imaging with a microscopy coil demonstrated well the details of the damaged parotid glands in patients with xerostomia. Quantitative MR imaging of fat, intact gland lobule, and number of sialoectatic foci significantly and highly correlated with severity of disease. Receiver operating characteristic (ROC) curve analysis demonstrated that quantitative MR imaging yielded high diagnostic ability in differentiating patients with xerostomia who have Sjogren's syndrome from those without Sjogren's syndrome, with areas under the ROC curve of 0.94 for fat area, 0.98 for intact lobule area, and 0.91 for number of sialoectatic foci. The best cutoff points by quantitative MR imaging were each associated with high sensitivity and specificity, and, when used in combination, yielded 96% sensitivity and 100% specificity. CONCLUSION: Quantitative MR imaging effectively differentiated the parotid glands in patients with xerostomia who have Sjogren's syndrome from those without the syndrome and provided criteria for staging the gland disease.

Adult↗
PubMed2004

MR imaging and MR spectroscopic imaging of prostate cancer.

The primary indication for prostate MR and MR spectroscopic imaging is evaluating men with newly diagnosed prostate cancer who are deciding whether to undergo surgery or radiotherapy. Other applications of MR and MR spectroscopic imaging in prostate cancer are not defined fully. Areas of research include volumetric localization of prostate cancer, in vivo MR spectroscopic imaging at high field strength, in vitro MR spectroscopic imaging at very high field strength, novel spectroscopic markers of malignancy,and interventional MR guidance of biopsy and therapy. MR spectroscopic imaging remains a relatively novel technique, and successful implementation is demanding. Nonetheless, only MR and MR spectroscopic imaging allow structural and metabolic evaluation of prostate cancer location, aggressiveness, and stage, and MR imaging provides clinically and therapeutically relevant information on prostatic and periprostatic anatomy.

Humans↗
PubMed1999

Intravascular MR imaging and intravascular MR-guided interventions.

Intravascular MR technology, using an intravascularly placed MR receiver probe to acquire high-resolution angiographic MR images (i.e. intravascular MR imaging) and to guide cardiovascular interventional therapies (i.e. intravascular MR-guided interventions), is a new, very attractive development in the field of MR imaging. The new technology offers unique advantages for cardiovascular imaging and interventions, including superior contrast capability and multiplanar imaging capabilities without the use of contrast agents and with no risk of ionizing radiation. Thecombination of intravascular MR techniques with other advanced MR imaging techniques, such as functional MR imaging, will open new avenues for the future comprehensive management of cardiovascular atherosclerotic disease. Further improvements in intravascular MR fluoroscopy with true real-time display, analogous to X-ray fluoroscopy, will dramatically establish the role of intravascular MR technology in modern medicine.

Journal Article↗
PubMed1999

A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner.

We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T2-weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner.

Artifacts↗
PubMed2004

Pretreatment evaluation of prostate cancer: role of MR imaging and 1H MR spectroscopy.

Magnetic resonance (MR) imaging and hydrogen 1 MR spectroscopy of the prostate gland are performed during the same examination with a conventional clinical MR unit. Prostate zonal anatomy and prostate cancer are best depicted on multiplanar T2-weighted MR images. MR imaging and 1H MR spectroscopy are not used as an initial diagnostic tool. Their use in tumor detection is reserved for patients with elevated prostate-specific antigen levels in whom previous biopsy results were negative. The use of MR imaging and 1H MR spectroscopy for the evaluation of tumor location, local extent (extracapsular extension and/or seminal vesicle invasion), volume, and aggressiveness is generating strong clinical interest. In staging and treatment planning, MR imaging has been shown to have an incremental value additive to the value of clinical nomograms. Furthermore, anatomic and metabolic mapping of the prostate gland with 1H MR spectroscopy offers the possibility of optimizing treatment planning (watchful waiting, surgery, or radiation therapy [intensity-modulated radiation therapy or brachytherapy]), thus further expanding the role of MR imaging in the achievement of patient-specific, individualized treatment.

Adenocarcinoma↗
PubMed2006

Evaluation of the acetabular labrum at 3.0-T MR imaging compared with 1.5-T MR arthrography: preliminary experience.

Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. The purpose of this study was to prospectively compare imaging of the acetabular labrum with 3.0-T magnetic resonance (MR) imaging and 1.5-T MR arthrography. Eight patients (four male, four female; mean age, 38 years) with hip pain suspicious for labral disease were examined at both MR arthrography and MR imaging. Presence of labral lesions, paralabral cysts, articular cartilage lesions, subchondral cysts, osteophytes, and synovial herniation pits was recorded. There was arthroscopic correlation of findings in five patients. MR imaging depicted four surgically confirmed labral tears that were identified at MR arthrography, as well as one that was not visualized at MR arthrography. MR imaging helped identify all other pathologic conditions that were diagnosed at MR arthrography and helped identify one additional surgically confirmed focal articular cartilage lesion. These results provide encouraging support for evaluation with 3.0-T MR imaging over 1.5-T MR arthrography.

Acetabulum↗
PubMed2006

Term neonate prognoses after perinatal asphyxia: contributions of MR imaging, MR spectroscopy, relaxation times, and apparent diffusion coefficients.

PURPOSE: To retrospectively evaluate magnetic resonance (MR) imaging, hydrogen 1 (1H) MR spectroscopy, apparent diffusion coefficient (ADC), T1, and T2 measurements for prediction of late neurologic outcome in term neonates after severe perinatal asphyxia. MATERIALS AND METHODS: This study was approved by the local ethics committee. Informed consent from parents was not required. Thirty term neonates (12 boys, 18 girls; age range, 2-12 days) with severe hypoxic-ischemic encephalopathy were examined during the first 12 days of life with conventional and diffusion-weighted cerebral MR imaging, 1H MR spectroscopy with absolute quantification, and T1 and T2 measurements. Quantitative 1H MR spectroscopy, T1, and T2 data were acquired on one 10-mm slab positioned at the level of the basal ganglia. The neonates were assigned to one of two groups according to their late (>12-month follow-up) neurologic outcome: those with an unfavorable outcome-that is, death or severe disability-and those with a favorable outcome. Clinical data, MR signal intensity abnormalities, ADCs, 1H MR spectroscopy findings, and relaxation times were compared by using Chi2 testing and analysis of variance to individualize the prognostic indicators. RESULTS: The unfavorable (n=16) and favorable (n=14) outcome groups were similar in terms of clinical data (ie, Apgar scores, visceral hypoxic injuries), visualization of brain edema on MR images, and T1 and T2 relaxation times. Late unfavorable neurologic outcome was associated with a mixed pattern of cortical and basal ganglia signal intensity abnormalities on MR images (13 babies with unfavorable vs three babies with favorable outcomes, P=.001) and with decreased absolute N-acetylaspartate (NAA) and choline concentrations in all brain structures, especially the basal ganglia (mean NAA concentration: 2.72 mmol/L in unfavorable outcome group vs 4.66 mmol/L in favorable outcome group, P<5x10(-9)), as measured with MR spectroscopy. In the basal ganglia, an NAA concentration lower than 4 mmol/L indicated an unfavorable individual prognosis with 94% sensitivity and 93% specificity. Significantly reduced ADCs also were noted in the unfavorable outcome group, but only during the first 6 days of life. CONCLUSION: Conventional MR imaging findings, spectroscopically measured absolute NAA and choline concentrations, and ADCs are complementary tools for predicting the individual outcomes of severely asphyxiated term neonates.

Age Factors↗
PubMed2001

MR imaging--guided large-core (14-gauge) needle biopsy of small lesions visible at breast MR imaging alone.

PURPOSE: To report our experience with magnetic resonance (MR) imaging-guided large-core breast biopsy of lesions visible at breast MR imaging only. MATERIALS AND METHODS: Stereotactic large-core (14-gauge) needle biopsy of 78 lesions visible at MR imaging only was performed with MR imaging guidance in 59 patients. Results were validated with excisional biopsy or mastectomy in 42 lesions and with radiologic-pathologic correlation and/or follow-up MR imaging for at least 2 years in another 17 lesions. The accuracy of MR imaging--guided core biopsy was determined for those 59 lesions with established validation. The effect on patient treatment was evaluated by comparing the prebiopsy treatment plan with the ultimate treatment. RESULTS: Histologic diagnosis from core biopsy was possible in 77 (99%) of 78 lesions. In the 59 lesions with established validation, the diagnostic accuracy of MR imaging--guided core biopsy was 98% (58 of 59). Successful MR imaging--guided core biopsy findings changed treatment in 70% (54 of 77) of lesions. Difficulties were due to the unsatisfactory performance of earlier types of MR imaging--compatible biopsy guns and decreasing target visibility during intervention. CONCLUSION: MR imaging--guided large-core stereotactic breast biopsy is sufficiently accurate for obtaining histologic proof of lesions visible only at MR imaging. It can change patient treatment by reducing unnecessary surgical biopsy and can enable one-step surgery for breast cancers.

Adult↗
PubMed1994

Germinomas of the basal ganglia and thalamus: MR findings and a comparison between MR and CT.

OBJECTIVE: The purpose of this study was to describe the MR imaging appearance of germinomas in the basal ganglia and thalamus and to compare the MR findings with CT findings. MATERIALS AND METHODS: Eleven MR studies of 10 patients with pathologically proved germinomas in the basal ganglia or thalamus were retrospectively reviewed. In nine of the 10, the MR findings were compared with CT findings. All patients were male, and all except one were in their second decade of life. All the tumors were located in paraventricular areas. RESULTS: Most of the tumors were 4-7 cm in diameter. MR images showed that the tumors were mostly cystic in five patients, mostly solid with cystic components in four, and solid without cystic components in one. The solid portion mostly was isointense relative to the cerebral cortex for all MR pulse sequences. The cystic portion was hyperintense relative to CSF on T1- and T2-weighted images. MR images showed intratumoral hemorrhage in seven patients. It appeared as an area of hyperintensity on T1- and T2-weighted images in five patients and as a fluid-fluid level with marked hypointensity on T2-weighted images in two. Hemorrhage was not visualized on CT scans in any patient. Flecked or amorphous calcifications visualized on CT scans in two patients were hardly detectable on MR images. Peritumoral edema was usually minimal. CT scans and MR images obtained after injection of contrast material both showed heterogeneous and dense enhancement in the solid portions of the tumors. CONCLUSION: MR images of germinoma in the basal ganglia and thalamus show a large paraventricular mass. Cystic areas, focal hemorrhages, and minimal surrounding edema are common. Unlike CT, MR imaging allows characterization of intratumoral hemorrhage.

Adolescent↗
PubMed1996

MR angiography of renal artery stenosis: value of the combination of three-dimensional time-of-flight and three-dimensional phase-contrast MR angiography sequences.

OBJECTIVE: It has been reported and also has been our preliminary experience that many false ostial stenoses are attributable to a loss of signal intensity at the origin of the renal arteries when three-dimensional (3D) phase-contrast MR angiography is used. Our objective was to add a 3D time-of-flight MR angiography sequence to the 3D phase-contrast MR angiography sequence to better analyze the origin of the main renal arteries. We assessed the value of the combination of these two MR angiography sequences for the depiction of renal artery stenosis. SUBJECTS AND METHODS: Forty-six patients suspected of having renal artery stenosis on the basis of clinical history, physical examination, and laboratory data were prospectively enrolled. Intraarterial digital subtraction angiography findings were available for all patients. Using intraarterial digital subtraction angiography, we considered stenosis to be significant when the vessel was narrowed more than 50%. During MR angiography, half of the data were reconstructed by interpolation to avoid long acquisition times. Total acquisition times were less than 15 min. MR angiography findings were interpreted independently by two radiologists who were unaware of the findings of intraarterial digital subtraction angiography. With 3D phase-contrast MR angiography, any cutoff in signal intensity or any narrowing of the vessel diameter of more than 50% from the renal ostium to the renal hilum was considered to represent significant stenosis. With 3D time-of-flight MR angiography, our image analysis was focused on the origin of the arteries. Any cutoff in signal intensity in the first centimeter of the renal artery was considered to represent significant stenosis. RESULTS: Intraarterial digital subtraction angiography showed 105 renal arteries, including 15 supernumerary renal arteries. Eleven stenoses were localized to the main hilar renal arteries. Using time-of-flight MR angiography, we found that polar supernumerary renal arteries of small caliber and intrarenal branches of renal arteries were not adequately displayed. Using phase-contrast MR angiography to evaluate only whether the main hilar renal arteries were stenotic, we calculated the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy to be 100%, 65%, 28%, 100%, and 69%, respectively. Using a combination of the two imaging sequences, we found that the specificity, positive predictive value, and accuracy were increased to 90%, 58%, and 92%, respectively. CONCLUSION: For detecting stenoses of the main renal arteries but not for visualizing small accessory renal arteries or distal branches, our results support the use of a combination of the two MR angiography sequences. For now, this combination of sequences should be viewed primarily as a technique for screening patients.

Adult↗
PubMed2002

Neuroimaging in pediatric brain tumors: Gd-DTPA-enhanced, hemodynamic, and diffusion MR imaging compared with MR spectroscopic imaging.

BACKGROUND AND PURPOSE: Gadolinium-enhanced MR images assist in defining tumor borders; however, the relation between tumor cell extent and contrast-enhanced regions is unclear. Our aim was to improve conventional neuroimaging of pediatric brain tumors with hemodynamic, diffusion, and spectroscopic MR imaging. METHODS: We performed conventional MR and MR spectroscopic imaging in 31 children with neuroglial brain tumors. Hemodynamic MR imaging was performed in 16 patients with a first-pass intravenous bolus of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA); apparent diffusion coefficients (ADCs) were measured in 12 patients. To account for multiple measurements in a patient, we used a nested analysis of variance. RESULTS: At MR spectroscopy, choline (Cho)-containing compounds (indicating tumor) and lipid levels (indicating necrosis) did not correlate with percent Gd-DTPA enhancement on MR images. Percent enhancement was positively correlated with relative cerebral blood volumes (rCBVs) (P =.05) and negatively correlated with ADCs (P <.001). Stepwise multiple linear regression revealed that rCBV (P =.008), ADC (P =.022), and lipid (P <.001) levels were significant independent predictors of percent enhancement. Tumor spectral patterns were detected in tumor regions and outside enhancing tumor beds in patients with clinical progression; these were confirmed at neuropathologic analysis. CONCLUSION: MR spectroscopic imaging improves the assessment of pediatric brain tumors by adding biochemical information regarding tumor involvement and by depicting residual or recurrent tumor outside the Gd-DTPA-enhanced tumor bed. rCBV and ADC mapping complemented MR spectroscopic imaging. We recommend the use of MR spectroscopic imaging in addition to conventional MR imaging in assessing pediatric brain tumors.

Adolescent↗
PubMed2003

Reproducibility of functional MR imaging results using two different MR systems.

BACKGROUND AND PURPOSE: In the application of functional MR imaging for presurgical planning, high reproducibility is required. We investigated whether the reproducibility of functional MR imaging results in healthy volunteers depended on the MR system used. METHODS: Visual functional MR imaging reproducibility experiments were performed with 12 subjects, by using two comparable 1.5-T MR systems from different manufacturers. Each session consisted of two runs, and each subject underwent three sessions, two on one system and one on the other. Reproducibility measures D (distance in millimeters) and R(size) and R(overlap) (ratios) were calculated under three conditions: same session, which compared runs from one session; intersession, which compared runs from different sessions but from the same system; and intermachine, which compared runs from the two different systems. The data were averaged per condition and per system, and were compared. RESULTS: The average same-session values of the reproducibility measures did not differ significantly between the two systems. The average intersession values did not differ significantly as to the volume of activation (R(size)), but did differ significantly as to the location of this volume (D and R(overlap)). The average intermachine reproducibility did not differ significantly from the average intersession reproducibility of the MR system with the worst reproducibility. CONCLUSION: The location of activated voxels from visual functional MR imaging experiments varied more between sessions on one MR system than on other MR system. The amount of the activated voxels is independent of the MR system used. We suggest that sites performing functional MR imaging for presurgical planning measure the intersession reproducibility to determine an accurate surgical safety margin.

Adult↗
PubMed1990

Effects of the benzomorphan kappa-opiate, MR 2266 and its (+) enantiomer MR 2267, on thermonociceptive reactions in different strains of mice.

The effects of the benzomorphan kappa opiate MR 2266 and its dextro enantiomer MR 2267 were assessed on thermonociception in Swiss Webster, C57BL/6, BALB/c and DBA/2 strains of mice. In the hot plate (60 +/- 0.5 degrees C, cut-off time 120 s and tail immersion tests, MR 2266 (10 mg/kg, s.c., 15 min before) decreased, while MR 2267 (10 mg/kg s.c., 15 min before) increased the reaction latencies. In the hot plate test, the sensitivities for the effects of MR 2266 and MR 2267 on jump latency in different strains of mice were as follows: MR 2266; BALB greater than Swiss greater than C57BL greater than DBA and MR 2267; DBA greater than BALB = Swiss greater than C57BL. In the immersion test, for the hyperalgesic response of MR 2266, the rank order of strains was; BALB greater than C57BL and DBA greater than or equal to Swiss while the rank order for the analgesic effect of MR 2267 was; Swiss greater than DBA and BALB. The results indicate the presence of tonic kappa-receptor-mediated regulation of the spinal and supra-spinal thermonociceptive reactions which is stereospecific and strain dependent.

Animals↗
PubMed2004

Evaluation of 9.4-T MR microimaging in assessing normal and defective fetal bone development: comparison of MR imaging and histological findings.

We evaluated 9.4-T magnetic resonance (MR) microimaging in assessing normal and defective bone development in mouse embryos. For this purpose, we performed 9.4-T MR microimaging on developing bones in normal embryos, and also in Runx2/Cbfa1-/- embryos with severely defective bone development. MR images were compared with the histological and histochemical features of these fetal bones. MR microimaging delineate successfully the normal long bone development in embryos. The T1- and T2-weighted MR microimaging demonstrated chondrocyte maturation in different regions of growing cartilage, such as epiphysis, physis, hypertrophic cartilage, and zone of provisional calcification. These developmental changes were detectable in as early as E14.5 embryos. The MR microimaging clearly demonstrated defective bone development in Runx2/Cbfa1-/- embryos. The femur from E18.5 homozygous Runx2/Cbfa1-/- embryos lacked MR signal intensity patterns including the hypertrophic cartilage, which are characteristic of the bone from the age-matched Runx2/Cbfa1+/+ embryos. Interestingly, however, the tibia from the same mutants was associated with MR signal patterns indicative of hypertrophic cartilage but not of the primary spongiosa and ossifying perichondrium, suggesting that bone development is differently regulated in these two long bones. On the other hand, the bones from heterozygous Runx2/Cbfa1+/- embryos exhibited an MR phenotype intermediate between the Runx2/Cbfa1+/+ and Runx2/Cbfa1-/- embryos; the primary spongiosa and ossifying perichondrium formation occurred normally even in the absence of preceding organized maturation of chondrocytes, a phenotype that was not detected by histological examinations. We concluded that MR microimaging is useful in assessing the bone development.

Animals↗
PubMedDate not supplied

MR 20492 and MR 20494: two indolizinone derivatives that strongly inhibit human aromatase.

In this study, we describe the synthesis of a new family of indolizinone derivatives designed to fit an extrahydrophobic pocket within the active site of aromatase and to strongly inhibit human aromatase. This could help improve the specificity of the inhibitors. Equine aromatase, very well characterized biochemically, is used as a comparative model. Indeed, in a previous comparison between both human and equine aromatases, we described the importance of the interaction between the inhibitor and this pocket for the indane derivative MR 20814. MR 20492 and MR 20494 are more potent inhibitors of human aromatase (Ki/Km: 1.0+/-0.3 and 0.5+/-0.3, respectively). The Ki/Km for MR 20494 is slightly higher than that obtained for fadrozole (0.1+/-0.0) and Ki/Km for both indolizinone derivatives are lower than those obtained for 4-hydroxyandrostenedione (1.9+/-0.8) and MR 20814 (8.1+/-.7). These new compounds are not enzyme inactivators. Moreover, as indicated by the higher Ki/Km values obtained with equine enzyme (9.0+/-0.6 and 6.1+/-1.6 for MR 20492 and MR 20494, respectively), both human and equine aromatase active sites appear to be structurally different. Difference absorption spectra study (350-500 nm) revealed that MR20492 and MR20494 were characterized by a combination of type-I and -II spectra with both enzymes. This result could be due to the isomerization of the molecule in polar solvent (Z and E forms). The evaluation of these new molecules, as well as 4-hydroxyandrostenedione and fadrozole, on aromatase activity in transfected 293 cell cultures evidenced a strong inhibition (IC50: 0.20+/-0.03 microM, 0.20+/-0.02 microM and 0.50+/-0.40 microM for MR 20494, fadrozole and 4-OHA, respectively) except for MR 20492 (3.9+/-0.9 microM) and MR 20814 (10.5+/-0.6 microM). These results proved that these molecules formed part of a promising family of potent inhibitors and that they penetrate 293 cells, without evidencing any cytotoxicity in Hela cells with MTT assay. This is thus encouraging for the development of new drugs for the treatment of estrogen-dependent cancers, these molecules also constitute new tools for understanding the aromatase active site.

Animals↗
PubMedDate not supplied

MR imaging-guided percutaneous nephrostomy and use of MR-compatible catheters in the nondilated porcine urinary tract.

PURPOSE: To investigate technique and practicability of MR-guided percutaneous nephrostomy (MRPCN) and to test magnetic resonance (MR)-compatible catheters inside the urinary tract. MATERIALS AND METHODS: In 10 healthy pigs, a percutaneous nephrostomy tube was placed into the nonobstructed pelvicaliceal system with use of exclusive MR guidance with a standard 1.5-T magnet. The urinary tract was visualized by intravenous injection of Gd-DTPA in combination with low-dose furosemide. The procedure was controlled with use of a T1-weighted turbo gradient-echo sequence in two orthogonal planes. The equipment for MRPCN included an 18-gauge MR-compatible puncture needle, a nitinol guide wire, and different 5-F MR catheters. RESULTS: In all 10 animals, the puncture needle was safely directed into the nondilated target calix. Slight deviations of the needle were detected on both MR image planes, which enabled immediate correction. This technique achieved a "first attempt" puncture of the targeted calix in each animal. MR images accurately demonstrated the dysprosium labelled tip of the different inserted catheters. It proved essential to inject a gadolinium-insaline solution via these catheters to preserve the endoluminal contrast enhancement as long as necessary. Balloon catheters were directed and inflated inside the ureter under exclusive MR guidance. Complications such as perforation and leakage were visualized by MR imaging. CONCLUSIONS: MRPCN is a promising technique for puncturing the pelvicaliceal system. The ability to successfully enter the urinary tract, even when it is nondilated, underscores the accuracy achievable with multiplanar MR imaging.

Animals↗
PubMed2003

White matter and cerebral metabolite changes in children undergoing treatment for acute lymphoblastic leukemia: longitudinal study with MR imaging and 1H MR spectroscopy.

PURPOSE: To assess the development of white matter and cerebral metabolite changes during and after treatment in children with acute lymphoblastic leukemia. MATERIALS AND METHODS: Twenty-three children (10 boys, mean age of 6.3 years; 13 girls, mean age of 6.6 years) with acute lymphoblastic leukemia were examined prospectively with magnetic resonance (MR) imaging and MR spectroscopy at 0, 8, and 20 weeks and 1, 2, and 3 years after diagnosis. White matter changes were diagnosed on the basis of hyperintense abnormalities on T2-weighted MR images. Single-voxel hydrogen 1 MR spectroscopy results from the right frontoparietal region of 21 children who received intravenous high-dose methotrexate were analyzed for cerebral metabolite changes. Multilevel models were used to assess the change in metabolites from baseline levels at subsequent follow-up. RESULTS: At 20 weeks, MR spectroscopy showed a significant reduction (P <.05) of mean N-acetylaspartate to choline ratio and increase in mean choline to creatine ratio (P <.05) in the children given high-dose methotrexate. This decline in N-acetylaspartate to choline ratio subsequently reversed and increased, possibly because of normal age-related brain maturation. Seventeen of 21 (81%) children showed metabolite changes at MR spectroscopy, while five of 22 (23%) showed white matter changes at MR imaging at 20 weeks. One more child developed white matter changes at 32 weeks. The associated changes resolved or reduced with time. CONCLUSION: MR spectroscopy demonstrated metabolite changes in the brain after high-dose methotrexate treatment in the absence of structural white matter abnormalities at MR imaging. MR spectroscopy might thus be a more sensitive method of monitoring the effects of high-dose methotrexate in the brain.

Adolescent↗