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A Roche

Publications and source records attributed to A Roche.

At least 37 records · Page 2Linked to original sources
PubMed2001

Three-dimensional multimodal brain warping using the demons algorithm and adaptive intensity corrections.

This paper presents an original method for three-dimensional elastic registration of multimodal images. We propose to make use of a scheme that iterates between correcting for intensity differences between images and performing standard monomodal registration. The core of our contribution resides in providing a method that finds the transformation that maps the intensities of one image to those of another. It makes the assumption that there are at most two functional dependencies between the intensities of structures present in the images to register, and relies on robust estimation techniques to evaluate these functions. We provide results showing successful registration between several imaging modalities involving segmentations, T1 magnetic resonance (MR), T2 MR, proton density (PD) MR and computed tomography (CT). We also argue that our intensity modeling may be more appropriate than mutual information (MI) in the context of evaluating high-dimensional deformations, as it puts more constraints on the parameters to be estimated and, thus, permits a better search of the parameter space.

Algorithms↗
PubMed2001

Rigid registration of 3-D ultrasound with MR images: a new approach combining intensity and gradient information.

We present a new image-based technique to rigidly register intraoperative three-dimensional ultrasound (US) with preoperative magnetic resonance (MR) images. Automatic registration is achieved by maximization of a similarity measure which generalizes the correlation ratio, and whose novelty is to incorporate multivariate information from the MR data (intensity and gradient). In addition, the similarity measure is built upon a robust intensity-based distance measure, which makes it possible to handle a variety of US artifacts. A cross-validation study has been carried out using a number of phantom and clinical data. This indicates that the method is quite robust and that the worst registration errors are of the order of the MR image resolution.

Algorithms↗
PubMed2001

Radiofrequency liver ablation: experimental comparative study of water-cooled versus expandable systems.

OBJECTIVE: We evaluate the uniformity and reproducibility of thermal lesion ablation and quantify the volume of tissue destruction and hemorrhage induced with two different commercially available radiofrequency ablation devices. MATERIALS AND METHODS: A four-array anchor expandable needle electrode and a triple-cluster cooled-tip needle electrode were used to induce lesions in three explanted calf livers and in vivo in eight swine livers. The sizes of the radiofrequency-induced lesions were macroscopically evaluated by measuring two perpendicular dimensions immediately after the experiment. Bleeding was evaluated by weighing gauze swabs used to dry the hemorrhage caused by electrode insertions. RESULTS: In explanted liver, the mean diameter of the radiofrequency-induced lesion was 5.3 +/- 0.7 cm for the cooled-tip needle and 3.7 +/- 0.4 cm for the expandable needle (p = 0.042), which correspond to approximate volumes of 65.35 +/- 26.22 cm(3) and 26.67 +/- 9.59 cm(3), respectively (p < 0.002). In vivo, the mean diameter was 3.7 +/- 0.4 cm for the cooled-tip needle and 3 +/- 0.4 cm for the expandable needle (p < 0.0001), which correspond to approximate volumes of 24.18 +/- 7.56 cm(3) and 11.16 +/- 3.65 cm(3), respectively (p < 0.0001). Blood loss attained a median value of 3.5 g for the cooled-tip needle and 2.6 g for the expandable needle; this difference was not statistically significant (p = 0.06). CONCLUSION: The cooled-tip needle induced significantly larger lesions than the expandable needle, but the lesions produced by the expandable needle are more reproducible, uniform, and spheric. The larger size of the lesions produced by the cooled-tip needle may be attributed to the higher maximum power used by the generator and the higher energy deposition, which is due to the cooling of the needle electrode.

Animals↗
PubMed2000

Transcatheter ethanol renal ablation in 20 patients with persistent urine leaks: an alternative to surgical nephrectomy.

PURPOSE: We evaluate the efficacy of transcatheter ethanol renal ablation for destruction of a unilateral, poorly functioning kidney with persistent urinary leaks from fistulas or a nephrostomy tube. MATERIALS AND METHODS: From January 1992 to January 1999, 19 females and 1 male with a history of pelvic neoplasms, which were responsible for ureteral leaks through the nephrostomy tube in 13 cases or fistulas in 7, were treated with transcatheter ethanol renal ablation. Serum creatinine ranged from 60 to 140 micromol./l. (mean 90), and function of the involved kidney determined by diethylenetetraminepentaacetic acid scintigraphy in 16 patients or by morphological imaging in 4 was low. Drainage of the renal cavities and antibiotic therapy preceded renal ablation. After epidural anesthesia or intravenous sedation renal ablation was performed by catheterization of the renal artery and injection of 1. 5 to 12 ml. (mean 4.6) absolute ethanol, and completed by proximal occlusion with coils and absorbable gelatin sponge. RESULTS: Arterial flow was interrupted in all cases. Urinary flow ceased in 2 days in 18 of 20 patients, and drains were removed. Two patients had residual urine that was successfully treated with additional embolization. No complications occurred. CONCLUSIONS: Transcatheter ethanol renal ablation is safe and effective, and permits an in situ nephrectomy that can replace surgical nephrectomy for treatment of urinary leaks.

Adolescent↗
PubMed2000

Radiofrequency ablation of 100 hepatic metastases with a mean follow-up of more than 1 year.

OBJECTIVE: The objective of our study was to evaluate the efficacy and safety of radiofrequency ablation of hepatic metastases performed either percutaneously for treatment of hepatic metastases in patients deemed ineligible for surgery or intraoperatively during partial hepatectomy to destroy unresectable metastases. SUBJECTS AND METHODS: Sixty-eight patients with 121 hepatic metastases (<5 metastases per patient) that were mainly colorectal in origin underwent 76 sessions of radiofrequency ablation with cooled-needle electrodes under sonographic guidance. Twenty-one patients with 33 metastases of 5-20 mm in diameter (mean +/- SD,13 +/- 7 mm) underwent intraoperative radiofrequency ablation. Forty-seven patients with 88 metastases of 10 to 42 mm in diameter (mean +/- SD, 26 +/- 9 mm) were treated with percutaneous radiofrequency ablation. Procedure efficacy was evaluated with dynamic enhanced CT and MR imaging performed 2, 4, and 6 months after treatment and then every 3 months. RESULTS: Radiofrequency ablation allowed eradication of 91% of the 100 treated metastases that were followed up for 4-23 months (mean, 13.7 months). Tumor control was equivalent for percutaneous radiofrequency ablation (90%) and for intraoperative radiofrequency ablation (94%). Failure to achieve tumor control occurred mostly with the largest tumor nodules. One bilioperitoneum and two abscesses were the major complications encountered after treatment of 121 metastases with a follow-up of more than 2 months. CONCLUSION: Radiofrequency ablation appears to be a promising therapeutic modality capable of extending the possibilities of partial hepatectomy and of efficiently treating small metastases percutaneously.

Adult↗
PubMed1999

Ecstasy use in Australia: patterns of use and associated harm.

This study explored patterns of ecstasy use and associated harm through the administration of a structured interview schedule to 329 ecstasy users, recruited from three Australian cities. A broad range of ecstasy users were interviewed, but on the whole, the sample was young, relatively well educated and most were employed or students. Patterns of use were varied, although extensive polydrug use was the norm. High rates of intravenous drug use were recorded, which may relate to an over-representation of chaotic intravenous polydrug users. Subjects had experienced an average of eight physical and four psychological side-effects, which they attributed to their ecstasy use in the preceding 6 months. Approximately 40% of the sample also reported financial, relationship and occupational problems. Young, female, polydrug users and those who binged on ecstasy for 48 h or more appeared most at risk of experiencing harm that they related to their ecstasy use. One-fifth of the sample had received treatment for an ecstasy-related problem, most often from a GP or natural therapist, and 7% were currently in treatment. One quarter wanted to reduce their use because of financial, relationship and psychological problems. A total of 15% wanted formal treatment for an ecstasy-related problem and 85% requested more information. These results have implications for the development of policies to respond to drug use among this population.

Adolescent↗
PubMed1999

MRI volume of the amygdala: a reliable method allowing separation from the hippocampal formation.

Studies of MRI-derived volume of the amygdala have been mostly performed on coronal sections where its boundaries with the hippocampus and the entorhinal cortex are indistinct. To date, all reports of in vivo amygdala volume have consistently overestimated the size of the structure. We have developed a method for the MRI-based in vivo measurement of the amygdala volume which allows a better separation of the amygdala from the adjoining hippocampal formation. In nine normal volunteers we obtained three-dimensional spoiled gradient recalled acquisition, 1.3-mm thick, T1 weighted sagittal MR images and created electronically linked reformatted images in the coronal and axial planes. On the original sagittal and the reformatted axial planes, where it is more readily apparent, we delineated the boundaries between the amygdala and the hippocampus and the amygdala and the hippocampo-amygdala transition area, respectively. We then projected those markings onto the coronal plane, where the other boundaries of the amygdala are more easily seen. Using these markings as a guide and utilizing extra-amygdalar coronal landmarks for the anterior end, we outlined the whole amygdala on the coronal plane and determined its volume. We observed that 45% of the coronal slices that contained amygdala also contained some hippocampus. The amygdala measurement had high test-retest reliability, with an intra-class correlation coefficient (rICC) of 0.99 for the total volume and an rICC of 0.93 for the measurement at the level of the individual slice. The average amygdala volume was 1.05 +/- 0.17 cm3 on the right and 1.14 +/- 0.15 cm3 on the left. Our amygdala volumes are in agreement with those reported in postmortem studies, which provides the reported method with face validity.

Adult↗
PubMed1999

Effect of growth hormone treatment on adult height of children with idiopathic short stature. Genentech Collaborative Group.

BACKGROUND: Short-term administration of growth hormone to children with idiopathic short stature results in increases in growth rate and standard-deviation scores for height. However, the effect of long-term growth hormone therapy on adult height in these children is unknown. METHODS: We studied 121 children with idiopathic short stature, all of whom had an initial height below the third percentile, low growth rates, and maximal stimulated serum concentrations of growth hormone of at least 10 microg per liter. The children were treated with growth hormone (0.3 mg per kilogram of body weight per week) for 2 to 10 years. Eighty of these children have reached adult height, with a bone age of at least 16 years in the boys and at least 14 years in the girls, and pubertal stage 4 or 5. The difference between the predicted adult height before treatment and achieved adult height was compared with the corresponding difference in three untreated normal or short-statured control groups. RESULTS: In the 80 children who have reached adult height, growth hormone treatment increased the mean standard-deviation score for height (number of standard deviations from the mean height for chronologic age) from -2.7 to -1.4. The mean (+/-SD) difference between predicted adult height before treatment and achieved adult height was +5.0+/-5.1 cm for boys and +5.9+/-5.2 cm for girls. The difference between predicted and achieved adult height among treated boys was 9.2 cm greater than the corresponding difference among untreated boys with initial standard-deviation scores of less than -2, and the difference among treated girls was 5.7 cm greater than the difference among untreated girls. CONCLUSION: Long-term administration of growth hormone to children with idiopathic short stature can increase adult height to a level above the predicted adult height and above the adult height of untreated historical control children.

Adult↗
PubMed1999

[The pinch-off syndrome: main cause of catheter embolism].

OBJECTIVE: To assess the incidence of the pinch-off syndrome (POS) in catheter fracture and embolism. STUDY DESIGN: Retrospective clinical study. PATIENTS: The medical files of 56 patients who had since 1989 an embolized fragment or entire catheter removed by an interventional radiologic procedure have been retrospectively analysed. METHODS: A POS was considered the causative factor when a chest X-ray showed a rupture of the catheter at the site of the costoclavicular space. RESULTS: From 1989 to the end of 1996, 56 catheter embolisms by fracture or disconnection occurred in our institution. The rupture from a POS was the main cause of embolism (24 patients out of 56). The incidence was 8/1000 of implanted ports inserted via a subclavian access [95% confidence interval: 4/1000-13/1000]. Preliminary clinical or radiologic signs of pinching existed in 50% of POS: difficult insertion, radiologic compression aspect, arm or shoulder pain, infusion rate and/or reflow depending on arm position. CONCLUSIONS: POS was the first cause of catheter embolism and should suggest the use of an alternative way for insertion instead of the subclavian access. When a catheter is inserted via a subclavian route, clinical and/or radiologic signs of POS require its removal.

Catheterization, Central Venous↗
PubMed1999

Synthesis of new hypoxia markers EF1 and [18F]-EF1.

We report on the preparation of a hypoxia marker 2-(2-nitroimidazol-1[H]-yl)-N-(3-fluoropropyl)acetamide (EF1) and its 18F analog, 2-(2-nitroimidazol-1[H]-yl)-N- (3-[18F]fluoropropyl)acetamide ([18F]-EF1). Two methods for the preparation of 3-fluoropropylamine, the EF1 side chain, are described. [18F]-EF1 was prepared with a radiochemical yield of 2% by nucleophilic substitution of bromine in 2-(2-nitroimidazol-1[H]-yl)-N-(3-bromopropyl)acetamide (EBr1) by carrier-added 18F in DMSO at 120 degrees C. Our results demonstrate the preparation of clinically relevant amounts of [18F]-EF1 for use as a non-invasive hypoxia marker with detection using positron emission tomography (PET).

Biomarkers↗
PubMed1999

Cystogastric transmural drainage for the treatment of symptomatic cystic metastases from ovarian carcinoma.

Approximately 80% of ovarian cancers are discovered when they have already progressed to stage III or IV lesions. The prognosis is, therefore, poor despite intensive treatment. Intraperitoneal dissemination is one of the most frequent pathways of distant spread ovarian cancer and pseudocystic metastases usually occur. When such cystic metastases remain symptomatic despite antitumor treatment, viable options are limited because palliative surgery generates high operative morbidity and mortality. For many years, in patients in whom the risks associated with surgery are high, percutaneous drainage and sclerosis under radiologic guidance has been performed as an effective alternative option for various forms of abdominal fluid collection. Such a collection in pancreatic pseudocyst benefits from cystogastric transmural drainage to avoid external drainage and achieves the same results as surgical cystogastrostomy. We report this transmural drainage technique under image guidance used to drain a symptomatic cystic metastasis, which was compressing the stomach.

Ascitic Fluid↗
PubMed1999

During liver regeneration following right portal embolization the growth rate of liver metastases is more rapid than that of the liver parenchyma.

BACKGROUND: The relative growth rates of human liver metastases are not known. The aim of this study was to determine in humans the growth rate of liver parenchyma during regeneration and the growth rate of liver metastases during the same process. METHODS: Among 556 patients hepatectomized for a malignant lesion, 48 underwent preoperative selective right portal vein embolization to induce hypertrophy of the left lobe. Five cases were selected because a liver metastasis was present inside the regenerating left lobe. The volumes of the liver metastasis and left lobe were measured with a three-dimensional technique on pre-embolization and postembolization computed tomography (CT) or CT arterial portography. The median interval between the two measurements was 34 (range 28-40) days. RESULTS: An increase occurred in the volume of the liver metastasis and the left lobe in the four patients with functionally intact liver parenchyma, but not in the patient with an impaired parenchyma. The volumetric increase of the normal liver varied from 59 to 127 per cent, compared with 60 to 970 per cent for the liver metastases. The ratio between the growth rate of the left lobe and the liver metastasis varied from 1.0 to 15.6. The growth rates of two metastases in the left lobe of a single patient were different. CONCLUSION: In functionally intact liver parenchyma, during hepatic regeneration or hypertrophy, the growth rate of metastases is more rapid that that of the liver parenchyma. However, a wide variation in growth rate is observed between patients and between metastases.

Aged↗
PubMed1999

New hemodynamic approach to angiogenesis: color and pulsed Doppler ultrasonography.

RATIONALE AND OBJECTIVES: To determine the capacity of color and spectral Doppler ultrasonography (US) to quantify angiogenesis in vivo and to characterize low-resistance intratumor blood flow. METHODS: Thirty-two tumors, xenografted into mice, were studied with Doppler US. The number of intratumor vessels visualized with color Doppler US was compared with the density of microvessels and the number of vessels >100 microm determined by histologic examination. The resistance index and the peak systolic velocities were evaluated. RESULTS: The number of intratumor vessels visualized by color Doppler US was correlated with the number of vessels >100 microm (P<0.001) determined histologically. When vessel density was >30, intratumor vessels were always detected by color Dopper US. The resistance index and peak systolic velocities were significantly lower in intratumor than in peritumor vessels. CONCLUSIONS: Color Doppler US evaluated tumor angiogenesis accurately. Spectral analysis confirmed the low resistance of intratumor blood flow.

Animals↗
PubMed1999

Percutaneous gastrostomy with fluoroscopic guidance: single-center experience in 500 consecutive cancer patients.

PURPOSE: To evaluate the feasibility, complications, adequacy of feeding support, and tolerability of fluoroscopically guided gastrostomy in cancer patients. MATERIALS AND METHODS: Five hundred cancer patients were referred for fluoroscopically guided gastrostomy, among whom percutaneous endoscopic gastrostomy was contraindicated or had been unsuccessful in approximately one-fourth. Five hundred eight fluoroscopically guided gastrostomies with T-fastener gastropexy were performed in 496 patients. The procedure was unsuccessful in four patients, and 12 patients needed a second gastrostomy. RESULTS: Fluoroscopically guided gastrostomy was feasible in 99% of patients. During the first 30 postprocedure days, there were seven major complications (1.4%): cardiac failure (n = 1), hemorrhage (n = 1), and peritonitis (n = 5); one patient died of peritonitis. No major complications occurred after the 30th postprocedure day. There were 27 minor complications (5.4%) during the first 30 postprocedure days and 88 (17.6%) thereafter. Long-term minor complications mainly involved the disturbances and nearly always resolved once the tube was exchanged. Such exchanges were easily performed under fluoroscopic guidance except in two patients, who required repeat fluoroscopically guided gastrostomy. CONCLUSION: Fluoroscopically guided gastrostomy is highly feasible and safe and provides adequate feeding support, even when percutaneous endoscopic gastrostomy is impossible. Long-term complications, which are mainly tube disturbances, are easily treated.

Adult↗
PubMed1999

[Chronic acquired hepatocerebral degeneration: the role of manganese and treatment by endovascular occlusion of a porto-systemic shunt].

This case report describes a 74 year-old woman with cirrhosis who developed choreo-athetotic movements associated with elevated whole blood manganese and symmetric hyperintense pallidum on T1-weighted magnetic resonance imaging. The diagnosis was chronic acquired hepatocerebral degeneration. The endovascular occlusion of portal-systemic shunts was temporarily effective.

Aged↗