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L E Olsson

Publications and source records attributed to L E Olsson.

At least 19 recordsLinked to original sources
PubMed2002

Gradient echo imaging of flowing hyperpolarized nuclei: theory and phantom studies on 129Xe dissolved in ethanol.

The influence of flip angle and flow velocity on the signal intensity achieved when imaging a hyperpolarized substance with a spoiled gradient echo sequence was investigated. The study was performed both theoretically and experimentally using hyperpolarized xenon dissolved in ethanol. Analytical expressions regarding the optimal flip angle with respect to signal and the corresponding signal level are presented and comparisons with thermally polarized substances are made. Both experimentally and theoretically, the optimal flip angle was found to increase with increasing flow velocity. Numerical calculations showed that the velocity dependence of the signal differs between the cases of hyperpolarized and thermally polarized substances.

Echo-Planar Imaging↗
PubMed2002

Echo-planar MR imaging of dissolved hyperpolarized 129Xe.

PURPOSE: The feasibility of hyperpolarized 129Xe for fast MR angiography (MRA) was evaluated using the echo-planar imaging (EPI) technique. MATERIAL AND METHODS: Hyperpolarized Xe gas was dissolved in ethanol, a carrier agent with high solubility for Xe (Ostwald solubility coefficient 2.5) and long relaxation times. The dissolved Xe was injected as a bolus into a flow phantom where the mean flow velocity was 15 cm/s. Ultrafast EPI images with 44 ms scan time were acquired of the flowing bolus and the signal-to-noise ratios (SNR) were measured. RESULTS: The relaxation times of hyperpolarized Xe in ethanol were measured to T1=160+/-11 s and T2 approximately 20 s. The resulting images of the flowing liquid were of reasonable quality and had an SNR of about 70. CONCLUSION: Based on the SNR of the obtained Xe EPI images, it was estimated that rapid in vivo MRA with 129Xe may be feasible, provided that an efficient, biologically acceptable carrier for Xe can be found and polarization levels of more than 25% can be achieved in isotopically enriched 129Xe.

Echo-Planar Imaging↗
PubMed2001

Cyclooxygenase-2 protein and prostaglandin E(2) production are up-regulated in a rat bladder inflammation model.

Cyclooxygenase-1 and cyclooxygenase-2 mRNAs and proteins and prostaglandin E(2) production are evaluated in a rat model of inflammation in which Escherichia coli lipopolysaccharide is intraperitoneally injected or intravesically instilled into the bladder. While cyclooxygenase-1 mRNA and protein and cyclooxygenase-2 mRNA do not change in bladders treated with lipopolysaccharide, cyclooxygenase-2 protein is elevated in bladders from rats intravesically instilled with lipopolysaccharide or phosphate buffered saline (PBS) or intraperitoneally injected with lipopolysaccharide. Urinary prostaglandin E(2) levels and prostaglandin E(2) synthesis in bladder particulates are elevated by intravesical instillation and intraperitoneal injection of lipopolysaccharide. The nitric oxide donor, S-nitroso-N-acetyl-D,L-penicillamine, increases prostaglandin E(2) synthesis in bladders from lipopolysaccharide intravesically instilled and intraperitoneally injected rats. Lipopolysaccharide increases prostaglandin E(2) synthesis by increasing cyclooxygenase-2 protein levels in rat bladder and prostaglandin E(2) synthesis may be further elevated by increases in nitric oxide caused by an up-regulation of inducible nitric oxide synthase (iNOS).

Administration, Intravesical↗
PubMed2001

Gd-DTPA2)-enhanced MRI of femoral knee cartilage: a dose-response study in healthy volunteers.

The negatively charged contrast agent Gd-DTPA2- distributes inversely to the cartilage fixed charged density. This enables structural cartilage examinations by contrast-enhanced MRI. In line with the development of a clinically applicable protocol for such examinations, this study describes the temporal pattern of Gd-DTPA2- distribution in femoral knee cartilage at three different doses in healthy volunteers. Nineteen volunteers (ages 21-28 years) were examined with a 1.5T MRI system. Quantitative relaxation rate measurements were made in weight-bearing central parts of femoral cartilage using sets of five turbo inversion recovery images with different inversion times. The cartilage was analyzed before and four times (1-4 h) after an intravenous injection of Gd-DTPA2- at single, double, and triple doses: 0.1, 0.2, and 0.3 mmol/kg body weight, respectively. The increase in R1 postcontrast was linearly dose-related at all times. The highest R1 values were registered at 2 and 3 h postcontrast, suggesting 2 h to be optimal in the clinical situation. The triple dose indicated a subtle compartmental difference in men, with higher contrast distribution medially than laterally. Results suggest that the triple dose is needed to detect minor cartilage matrix differences.

Adult↗
PubMed2001

Prospective patient-reported continence after laparoscopic radical prostatectomy.

OBJECTIVES: To perform a prospective study using confidential patient-completed questionnaires about their urinary habits before and after laparoscopic radical prostatectomy. Published reports on urinary continence after radical prostatectomy vary depending on the definitions of urinary continence and methods of data collection. METHODS: From May 1998 to February 2000, 228 men underwent laparoscopic radical prostatectomy for clinically localized prostate cancer. The patients were given questionnaires before surgery and at 1, 3, 6, and 12 months postoperatively. RESULTS: Before surgery, no patient reported incontinence. At 1, 3, 6, and 12 months postoperatively, perfect diurnal urinary control (no pads, no leakage at all) was reported in 9.9%, 28.6%, 57.4%, and 56.8% of patients, respectively. No pads were used in 18.8%, 58.4%, 68.9%, and 78.4% at 1, 3, 6, and 12 months, respectively. No patient reported use of more than 1 pad daily at 6 months of follow-up. CONCLUSIONS: Continence after laparoscopic radical prostatectomy is comparable to the results after traditional radical retropubic prostatectomy. Ongoing use of the laparoscopic route for treating clinically localized prostate cancer is warranted.

Aged↗
PubMed2001

Laparoscopic radical prostatectomy with a remote controlled robot.

PURPOSE: Robotics in surgery is a recent innovation. This technology offers a number of attractive features in laparoscopy. It overcomes the difficulties with fixed port sites by restoring all 6 degrees of freedom at the instrument tips, provides new possibilities for miniaturization of surgical tasks and allows remote controlled surgery. We investigated the applicability of remote controlled robotic surgery to laparoscopic radical prostatectomy. MATERIALS AND METHODS: Our previous experience with laparoscopic prostatectomy served as a basis for adapting robotic surgery to this procedure. A surgeon at a different location who activated the tele-manipulators of the da Vinci* robotic system performed all steps of the intervention. A scrub nurse and second surgeon who stood at patient side had limited roles to port and instrument placement, exposure of the operative field, assistance in hemostasis and removal of the operative specimen. Our patient was a 63-year-old man presenting with a T1c tumor discovered on 1 positive sextant biopsy with a 3+3 Gleason score and 7 ng./ml. preoperative serum prostate specific antigen. RESULTS: The robot provided an ergonomic surgical environment and remarkable dexterity enhancement. Operating time was 420 minutes, and the hospital stay lasted 4 days. The bladder catheter was removed 3 days postoperatively, and 1 week later the patient was fully continent. Pathological examination showed a pT3a tumor with negative margins. CONCLUSIONS: Robotically assisted laparoscopic radical prostatectomy is feasible. This new technology enhances surgical dexterity. Further developments in this field may have new applications in laparoscopic tele-surgery.

Humans↗
PubMed2001

Laparoscopic radical prostatectomy. The Créteil experience.

OBJECTIVES: In an effort to reduce the morbidity associated to radical prostatectomy, we implemented laparoscopic surgery to this advanced ablative and reconstructive procedure. In our study, we describe our operative technique and assess our results in terms of oncologic cure, continence and potency. METHODS: 200 patients with clinically localized prostate cancer underwent laparoscopic radical prostatectomy. 66 of these patients were either referred, or operated during surgical demonstrations. Thus, complete evaluation is based on a homogeneous personal series of 134 patients and was performed by an independent clinical analyst. There were 91 T1 and 43 T2. We did not perform pelvic lymph node excision in 78 patients whose PSA was less than 10 ng/ml and the Gleason score of endorectal biopsies was below 7. The surgical procedure recapitulated the steps of traditional retropubic prostatectomy with one basic difference however: the first step of the technique consisted in a rectoprostatic cleavage, which was done transperitoneally. Except for the first 10 patients, the vesicourethral reconstruction was performed either with two hemi-circumferential or a single circumferential running suture. RESULTS: All interventions were performed as planned, no conversions were necessary, and only 4 patients required blood transfusion. Operating time decreased with growing experience; after the first 20 patients the usual operating time was 3.5 h without and 4 h with lymphadenectomy. The surgical complication rate was 22.5% in the first 40 patients, and 3.2% in the remaining 94 patients. Except for the first 10 patients, the mean hospital stay was 6.1 days and bladder catheterization 4.8 days. Median catheterization time was 4 days. Histological study of the specimen showed pT2 disease in 101 patients and pT3 in 33 patients, the rate of positive margins was 16.8 and 48.8%, respectively. At 1 year, overall erection rate (with or without sexual intercourse) was 56%, the rate of patients without pad was 86.2% during the day and 100% during the night. CONCLUSIONS: Laparoscopic environment seems to comply with the oncologic goals of radical prostatectomy. Improved intraoperative visualization and magnification may provide benefits for the preservation of continence and potency by allowing a more precise dissection and vesicourethral reconstruction. Despite longer operative times and the steep learning curve this new technique is currently proliferating due to expectations of decreased postoperative morbidity and better quality of life.

Aged↗
PubMed2001

Retroperitoneal laparoscopic living-donor nephrectomy. Preliminary results.

PURPOSE: Living-donor nephrectomy is performed via a standard flank approach during open surgery in contrast to laparoscopy where kidneys are procured transperitoneally. Being more familiar with retroperitoneal laparoscopy for the surgery of the upper urinary tract, we investigated the feasibility of live donor nephrectomy by this approach. MATERIAL AND METHODS: We performed laparoscopic retroperitoneal left-sided nephrectomy in 3 living donors. The patients were placed in lumbotomy position. The retroperitoneal space was developed with blunt finger dissection, through a 2-cm mini-lumbotomy under the 12th rib in the posterior axillary line. 5 trocars were inserted. After primary access to the renal artery and vein, these were dissected to their junctions with the aorta and inferior vena cava, respectively, before freeing the kidney of its perinephric attachments. The kidney was delivered manually, through the slightly enlarged initial subcostal incision. RESULTS: The average duration of surgery was 83 min; warm ischemia time less than 5 min. Average blood loss was 120 cm(3). Donors did not present any postoperative morbidity and were discharged after an average of 2.3 days. Mean analgesic requirement was 5 mg morphine sulphate equivalent (0-15). Average convalescence was 13.3 days (10-18). All 3 kidneys harvested laparoscopically had immediate function with urine production after graft revascularization; serum creatinine levels returned to normal within 1 week. The first patient presented ureteral stenosis 2 months after surgery. He underwent ureteropyeloplasty using his native ureter. CONCLUSIONS: Laparoscopic living-related-donor nephrectomy become a new standard for organ harvesting. Our data suggest that retroperitoneal laparoscopic donor nephrectomy may represent a reasonable option in centers in which more extensive experience has been accumulated with retroperitoneal than with transperitoneal laparoscopy for the surgery of the upper urinary tract.

Female↗
PubMed2001

Early removal of the catheter after laparoscopic radical prostatectomy.

PURPOSE: We prospectively tested the safety of routine removal of the catheter as early as 2 to 4 days after laparoscopic radical prostatectomy. MATERIALS AND METHODS: Between March 1998 and March 2001, 228 patients underwent laparoscopic radical prostatectomy for clinically organ confined prostate cancer. The last 113 consecutive patients were included in a prospective study according to gravitational cystography performed 2 to 4 days postoperatively. If no leak was seen the catheter was removed. If a leak was apparent the catheter was left indwelling for another 6 days and cystography was repeated. RESULTS: Cystography 2 to 4 days postoperatively showed an anastomosis without a leak in 96 (84.9%) patients who subsequently had the catheters removed. There were 28 patients who had the catheter removed on postoperative day 2, 28 day 3 and 40 day 4. In 17 (15.1%) patients an anastomotic leak was observed, and the catheter was not removed at that time. Of the 96 patients in whom the catheter was removed early 10 (10.4%) had urinary retention that necessitated re-catheterization. This procedure was performed without the need for cystoscopy. After the catheter was removed all patients were able to void 24 hours later. Median followup was 7 months (range 1 to 15) and showed continence rates greater than 93%. No anastomotic stricture, pelvic abscess or urinoma developed in any patient. CONCLUSIONS: Patients who undergo laparoscopic radical prostatectomy can have the catheter safely removed 2 to 4 days postoperatively without a higher risk of incontinence, stricture or leak related problems.

Humans↗
PubMed2000

Image analysis methods for assessing levels of image plane nonuniformity and stochastic noise in a magnetic resonance image of a homogeneous phantom.

Magnetic response image plane nonuniformity and stochastic noise are properties that greatly influence the outcome of quantitative magnetic resonance imaging (MRI) evaluations such as gel dosimetry measurements using MRI. To study these properties, robust and accurate image analysis methods are required. New nonuniformity level assessment methods were designed, since previous methods were found to be insufficiently robust and accurate. The new and previously reported nonuniformity level assessment methods were analyzed with respect to, for example, insensitivity to stochastic noise; and previously reported stochastic noise level assessment methods with respect to insensitivity to nonuniformity. Using the same image data, different methods were found to assess significantly different levels of nonuniformity. Nonuniformity levels obtained using methods that count pixels in an intensity interval, and obtained using methods that use only intensity values, were found not to be comparable. The latter were found preferable, since they assess the quantity intrinsically sought. A new method which calculates a deviation image, with every pixel representing the deviation from a reference intensity, was least sensitive to stochastic noise. Furthermore, unlike any other analyzed method, it includes all intensity variations across the phantom area and allows for studies of nonuniformity shapes. This new method was designed for accurate studies of nonuniformities in gel dosimetry measurements, but could also be used with benefit in quality assurance and acceptance testing of MRI, scintillation camera, and computer tomography systems. The stochastic noise level was found to be greatly method dependent. Two methods were found to be insensitive to nonuniformity and also simple to use in practice. One method assesses the stochastic noise level as the average of the levels at five different positions within the phantom area, and the other assesses the stochastic noise in a region outside the phantom area.

Image Processing, Computer-Assisted↗
PubMed2000

Dose response characteristics and basic dose distribution data for a polymerization-based dosemeter gel evaluated using MR.

A safe and reproducible mixing procedure for the manufacture of a polymerization-based dosemeter gel evaluated using MRI (PoMRI) is presented. The dose response, obtained by irradiating gel-filled vials with absorbed doses in the interval 0-20 Gy and evaluated with respect to 1/T2, was found to be linear in the interval 0-8 Gy, with a sensitivity of 0.211 s-1Gy-1 (r2 = 0.998) at 1.5 T. Evaluation of the same set of vials with respect to 1/T1 gave a sensitivity of 0.018 s-1Gy-1 (r2 = 0.960). PoMRI and diode data were compared for standard photon and electron treatment beams. A deviation of less than 3% was found between the two methods for central depth dose curves as well as dose profiles (2 mm for electrons in the steep dose gradient regions). The importance of the method used for background correction for the reliability of the results was also evaluated. Barex (with a wall thickness of 1.5 mm) was investigated for use as phantom material and found to be favourable compared with glass. The results obtained in this study show that PoMRI has excellent potential as a 3D detector.

Dose-Response Relationship, Radiation↗
PubMed1999

Image artifacts due to a time-varying contrast medium concentration in 3D contrast-enhanced MRA.

The purpose of this work was to study image effects due to time-varying contrast medium concentration in contrast-enhanced three dimensional (3D) magnetic resonance angiography (MRA) images. Two different simulation models (1D and 3D) and two different contrast medium variation schemes were used. Phantom measurements were also performed. Experiments were performed for several different bolus timings. Similar sequence and image object parameters were used in both simulations and measurements (TE/TR 2. 1/7.8 mses, flip angle 30 degrees, T1/T2 1200-80/150-40 msec, flow velocity 100 cm/sec). A small variation in bolus timing yielded large variations in the appearance of the image effects, especially if the center of k-space was sampled in the vicinity of rapid contrast medium concentration variation. For a typical bolus injection in a patient, a severe signal loss but only minor ringing and edge artifacts appeared if the bolus injection was poorly timed. Effects of pulsatile flow were minor. The 3D model proved to be a useful tool in these studies. J. Magn. Reson. Imaging 1999;10:919-928.

Aorta↗
PubMed1999

MRI image plane nonuniformity in evaluation of ferrous sulphate dosimeter gel (FeGel) by means of T1-relaxation time.

MR image nonuniformity can vary significantly with the spin-echo pulse sequence repetition time. When MR images with different nonuniformity shapes are used in a T1-calculation the resulting T1-image becomes nonuniform. As shown in this work the uniformity TR-dependence of the spin-echo pulse sequence is a critical property for T1 measurements in general and for ferrous sulfate dosimeter gel (FeGel) applications in particular. The purpose was to study the characteristics of the MR image plane nonuniformity in FeGel evaluation. This included studies of the possibility of decreasing nonuniformities by selecting uniformity optimized repetition times, studies of the transmitted and received RF-fields and studies of the effectiveness of the correction methods background subtraction and quotient correction. A pronounced MR image nonuniformity variation with repetition and T1 relaxation time was observed, and was found to originate from nonuniform RF-transmission in combination with the inherent differences in T1 relaxation for different repetition times. The T1 calculation itself, the uniformity optimized repetition times, nor none of the correction methods studied could sufficiently correct the nonuniformities observed in the T1 images. The nonuniformities were found to vary considerably less with inversion time for the inversion-recovery pulse sequence, than with repetition time for the spin-echo pulse sequence, resulting in considerably lower T1 image nonuniformity levels.

Background Radiation↗
PubMed1999

Ferrous sulphate gel dosimetry and MRI for proton beam dose measurements.

Ferrous sulphate gel dosimetry has the potential for measurement of absorbed dose distributions in proton therapy. The chemical properties of the gel are altered according to the radiation dose and these changes can be evaluated in three dimensions using MRI. The purpose of this work was to investigate the properties of a ferrous gel used with clinical proton beams. The gel was irradiated with both monoenergetic and range-modulated proton beams. It was then evaluated using MRI. The depth dose by means of the 1/T1 distribution was studied and compared with data from a plane-parallel plate ionization chamber. 1/T1 was shown to be proportional to the dose at a mean proton energy of approximately 90 MeV. The dose response was no different from that obtained using photon beams. However, on normalization at the entrance, the relative 1/T1 at the Bragg peak was 15-20% lower than the corresponding ionization chamber data for the monoenergetic proton beam. Better agreement was found for the modulated beam, but with significant differences close to the distal edge of the 1/T1 distribution. The change in sensitivity with depth was explained by means of a linear energy transfer dependence. This property was further studied using Monte Carlo methods.

Calibration↗
PubMed1998

Pleurotomy, pneumothorax, and surveillance during living donor nephroureterectomy.

OBJECTIVES: To determine the incidence of and risk factors associated with pneumothorax after donor nephroureterectomy and to determine the utility of postoperative chest roentgenography. METHODS: A retrospective review was made of 130 living donor nephroureterectomies performed at one institution (Yale-New Haven Hospital) using an extraperitoneal flank incision. RESULTS: Incidental pleurotomy occurred in 11 cases (8.5%). Rib resection was associated with pleurotomy. Patient age, sex, and side of operation were not associated with pleurotomy. Ten (91 %) of the 11 cases were identified intraoperatively. One unrecognized pneumothorax was identified postoperatively with chest roentgenography; no specific intervention was necessary. CONCLUSIONS: The extraperitoneal flank incision poses a significant risk for pneumothorax. Most pneumothoraces will be recognized intraoperatively. No adverse effects were noted secondary to pneumothorax.

Adolescent↗
PubMed1998

Verification of single beam treatment planning using a ferrous dosimeter gel and MRI (FeMRI).

A method for analysing and comparing treatment planning system (TPS) data and ferrous dosimeter gel measurements evaluated with MRI (FeMRI) was developed, including image processing to final absorbed dose images. Measurements were analysed according to this method and FeMRI data were thereby compared with the TPS-calculated dose distribution. For photons, differences between FeMRI- and TPS dose data were mainly within +/- 2%. Minor shortcomings found in both the FeMRI system and the TPS are explained and discussed. For electron beams, there was an overall good agreement. It was found that the TPS underestimates the lateral scattering dose outside the primary beam, but the reported dose difference corresponds to a small spatial deviation (less than 2 mm). It is important to consider this single beam data comparison when the method is extended to more complicated situations, for example when using several beams.

Ferrous Compounds↗