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M Lönnemark

Publications and source records attributed to M Lönnemark.

17 recordsLinked to original sources
PubMed2005

Computed-tomography-guided punctures using a new guidance device.

PURPOSE: To evaluate a new adjunctive guidance device, a puncture guide, constructed to simplify computed tomography (CT)-guided punctures and to make the procedure more accurate and safe. MATERIAL AND METHODS: 17 patients referred for CT-guided punctures were included in the study. There were 10 thoracic and 7 abdominal or pelvic lesions with a mean maximum diameter of 29 +/- 18 mm. All punctures were performed using a laser guide combined with the new device. The needle guide created a streak artefact in the image, indicating the needle path. RESULTS: The puncture was successful at the first attempt in 15 of the 17 patients. The artefact was visible in all patients, and in the majority there was a distinct artefact reaching from the entry point to the lesion. The deviation between the angle of the streak artefact and the final angle of the needle was 1.1 degrees. CONCLUSION: The benefits of the puncture guide were the artefact pointing at the target, the needle support, and accuracy when performing CT-guided punctures.

Abdominal Cavity↗
PubMed1999

Diagnostic imaging of foreign body reactions in dogs with diffuse back pain.

Six hunting dogs were investigated after showing signs of diffuse back pain. In three of the dogs, prodromal signs included coughing. Swelling in the dorsal lumbar region was noted in four of the dogs, but in two there was no visible or palpable swelling. Initial radiographs of the lumbar region were normal in two of the dogs and showed mild to moderate ventral periosteal reactions in the L1 to L4 region in the remaining four. On ultrasonography and magnetic resonance imaging, changes were seen in the sublumbar muscles (e.g., abnormal echogenicity and increased signal intensity) in five dogs examined. Exploratory surgery revealed plant material foreign bodies in the sublumbar muscles in the L1 to L4 region in five of the six dogs. The concurrent infections were caused predominantly by anaerobic bacteria common to the mucous membranes of the oropharyngeal and respiratory tracts. All dogs recovered, with restored hunting ability. The mean follow-up period was five years (range 1.3 to 7.8 years). It is proposed that the plant parts were inhaled, and then migrated along either diaphragmatic crus to lodge in the sublumbar muscles.

Animals↗
PubMed1995

Oral contrast media in CT of the abdomen. Iohexol of different concentrations as a gastrointestinal contrast medium.

In a double-blind randomised study 3 different concentrations of iohexol for bowel opacification at CT of the abdomen were compared. Iohexol in a concentration of 4.5 mg I/ml, 6.75 mg I/ml and 9 mg I/ml was used. No significant differences between the 3 preparations of contrast media were found regarding the contrast effect, the distribution or patient tolerance. When using iohexol as a bowel contrast medium at CT the concentration of 4.5 mg I/ml is sufficient for bowel opacification.

Administration, Oral↗
PubMed1994

Frequency of proximal tubal obstruction in patients undergoing infertility evaluation.

Fallopian tube recanalization is a technique for treatment of proximal tubal obstruction caused by debris. The true frequency of infertile women for whom this treatment is suitable is not well known. In this study all hysterosalpingograms (HSGs) performed over a 3-year period (1986-88) were reviewed. The HSGs were performed as part of an infertility evaluation program in 494 women, with a mean duration of infertility of 2.4 years. Bilateral proximal tubal obstruction was found in 3% and unilateral proximal obstruction in 2% of the cases. In women examined in the first 2 years (1986-87) (n = 328), the birth frequency after HSG was 25%. When HSG was performed with optimal technique the number of patients who were suitable for Fallopian tube recanalization was low.

Adult↗
PubMed1993

Staging of bladder carcinoma by computer tomography-guided transmural core biopsy.

In an attempt to improve staging of bladder cancer, computed tomography-guided transmural core biopsy was performed in 17 patients. In the first four patients a 0.9 mm cutting needle was used. This small needle yielded easily fragmented cores and consequently the remaining biopsies were taken with a 1.2 mm needle with an improved result. In all but one case sufficient histological material to allow a diagnosis was obtained by the core biopsy technique. Transmural tumor infiltration, as verified in corresponding cystectomy specimens, could be identified more often with the core biopsy than in biopsies obtained by transurethral resection. False negative diagnosis occurred when the tumor was not clearly visible on the computed tomography scan. No short-term side effects of clinical importance were found with the procedure.

Adenocarcinoma↗
PubMed1993

Oral contrast media in CT of the abdomen. A double-blind randomized study comparing an aqueous solution of amidotrizoate, an aqueous solution of iohexol and a viscous solution of iohexol.

In a double-blind randomized study 3 different preparations of oral contrast media for bowel opacification at CT of the abdomen have been compared. Plain aqueous solutions of amidotrizoate (9 mg I/ml) and iohexol (9 mg I/ml) were used as well as a preparation of iohexol (9 mg I/ml) to which a viscosity-increasing agent had been added. The distribution of the contrast media in the intestine, transit time and patient tolerance were evaluated. No significant differences were found regarding the distribution between the 3 preparations of contrast media, while there was a tendency for the transit time to be increased when the viscous preparation of iohexol was used. The aqueous solution of iohexol had the best taste, while the viscous preparation was markedly more difficult to drink. Aqueous solutions of iohexol and amidotrizoate were equal for bowel opacification and the addition of the viscosity-increasing agent did not improve the distribution of the contrast medium in the intestine.

Administration, Oral↗
PubMed1991

Effect of superparamagnetic particles in agarose gels. A magnetic resonance imaging study.

The effect of different preparations of superparamagnetic particles, designed as potential MR contrast media for the gastrointestinal tract (oral magnetic particles, OMP, diameter of 3.5 microns, iron content 20% by weight) and for the reticuloendothelial system (intravenous magnetic particles, IMP, mean diameter of 0.3 micron, iron content 30% by weight), were evaluated in agarose gels in vitro, using a 0.5 T whole body MR system. The iron content ranged from 2.1 x 10(-4) to 2.1 x 10(-1) mg Fe/ml in both preparations. Both preparations reduced the signal intensities substantially over a range of concentrations in spin echo sequences. Generally, the signal intensity decreased monotonously with concentration, except for IMP at low concentrations, at which a minor signal intensity increase was observed on T1 and proton density weighted images. The reduction of the signal intensity was stronger in gradient echo and phase contrast sequences, as compared to corresponding spin echo sequences with similar timing. Both IMP and OMP had a pronounced T2 effect, the effect of IMP being stronger than that of OMP. IMP had a relatively smaller T1 effect, whereas T1 was almost unaffected by OMP. Susceptibility artifacts occurred at higher concentrations of both OMP and IMP, in all sequences used. Thus, OMP reduced the signal intensity, without causing significant artifacts, on both T1 and T2 weighted images over a relatively wide range of concentrations.

Contrast Media↗
PubMed1991

Superparamagnetic particles as oral contrast medium in MR imaging of malignant lymphoma.

Non-biodegradable superparamagnetic particles, in plain and viscous aqueous suspensions, were used as an oral contrast medium in 34 patients with known or suspected malignant lymphoma. The contrast effect, the occurrence of artifacts, and the distribution were evaluated in the plain and the viscous aqueous suspensions, and the diagnostic information received from abdominal MR examinations performed without bowel contrast medium was compared with that of post-contrast examinations. Magnetic particles in the concentration of 0.5 g/l displayed a good contrast effect at 0.5 T, and helped in differentiating the intestine from adjacent tissues, resulting in increased diagnostic information in abdominal MR imaging. In the patients given the viscous aqueous suspension the occurrence of artifacts caused by the magnetic particles decreased considerably, and the distribution was homogeneous and improved compared with that in patients given the plain aqueous suspension.

Abdomen↗
PubMed1990

Oral superparamagnetic particles for magnetic resonance imaging. Effect in plain and viscous aqueous suspensions.

As a potential gastrointestinal MR contrast medium magnetic particles have been evaluated in preclinical studies as well as in healthy volunteers. The main problem was to achieve an even distribution of the aqueous suspension of magnetic particles in the entire intestine. To improve the distribution of the contrast medium, a viscosity-increasing agent was added to the preparation. In the plain aqueous suspension the magnetic particles sedimented rapidly and caused artifacts, whereas no such sedimentation occurred in the viscous preparation. The contrast effect, as well as the presence of artifacts, increased with particle concentration. The general contrast effect was good in all 5 volunteers, and the contrast medium was well distributed in the small intestine, including the duodenum. There were no artifacts observed, and the contrast medium was well tolerated. The viscosity-increasing agent will thus be introduced in further clinical studies.

Adult↗
PubMedDate not supplied

Uptake of mangafodipir trisodium in liver metastases from endocrine tumors.

The purpose of the study was to investigate retrospectively whether mangafodipir trisodium (MnDPDP) can enhance the liver metastases from endocrine tumors. Thirteen patients with endocrine tumors and liver metastases underwent T1-weighted spin-echo (SE) and turbo gradient-echo (GRE) MRI conducted before and 20 to 60 minutes after i.v. infusion of MnDPDP. Additional 24-hour-delay scans were performed in 8 of 13 patients. MR signal intensity (SI) was measured in liver parenchyma and metastases, which was then related to that of paraspinal muscle. A total of 30 lesions on precontrast and postcontrast images and 18 lesions on 24-hour-delay images were measured. An enhancement by 49% in SE and 40% in GRE images (P = .0001) was observed in tumor tissues after MnDPDP infusion. In 24-hour-delay images, the SI of the lesions remained relatively high, but in liver parenchyma, it decreased significantly, and the tumor-liver tissue contrast was reduced.

Adult↗
PubMedDate not supplied

MR-cholangiography with a double contrast technique.

The combination of superparamagnetic particles (SPP) as a 'negative' contrast agent for the liver parenchyma and Cr-HIDA as a 'positive' one for the bile ducts was tested in dogs. The maximum effect of SPP was present about 30 minutes after injection with a reduction of the image intensity of the liver close to the background noise level at the highest dosages. This effect lasted for about 4 to 5 hours and it had disappeared after 24 hours. Before any contrast administration or after Cr-HIDA the bile ducts were not discernible, but a high signal in the gallbladder was present 15 to 30 minutes after injection of Cr-HIDA. After SPP the wider bile ducts were discernible because of the lowering of the signal intensity in the liver. When SPP were followed by Cr-HIDA, the bile had a higher signal intensity, and even tiny bile ducts were visible. After cholecystokinin visualization of the choledochus duct was achieved as well as contrast filling of the duodenum. The blood, urine, and liver function tests were found normal during the experiments. The combination of superparamagnetic particles and Cr-HIDA seems to be a promising method for MR-cholangiography. An evaluation of the anatomic structures of the liver should be possible with this method in different pathologies.

Animals↗
PubMedDate not supplied

Effect of superparamagnetic particles as oral contrast medium at magnetic resonance imaging. A phase I clinical study.

Non-biodegradable superparamagnetic particles were used as an oral contrast medium in different concentrations, and evaluated in 25 human volunteers. The aim of the study was to determine the most appropriate concentration of the contrast medium, and to evaluate the effect, distribution, safety and tolerance. With the concentration of 1.0 g/l a substantial reduction of the signal intensity in the bowel was achieved in both T1 and T2 weighted images. The intraabdominal structures were well differentiated from the bowels containing contrast medium. 'Metal' artifacts and blurring of adjacent structures, probably due to an increased local concentration, were observed at higher dosages. The distribution of the preparation in the gastrointestinal tract varied between individuals. As a rule a good contrast effect was achieved in the small bowel with the exception of the duodenum. The contrast medium was well accepted and did not cause any side effects of clinical importance. The results suggest that the preparation is well tolerated by humans and may be a useful contrast medium for abdominal MR imaging.

Contrast Media↗
PubMedDate not supplied

Superparamagnetic particles as an MRI contrast agent for the gastrointestinal tract.

Non-biodegradable superparamagnetic particles containing magnetite were evaluated as a potential contrast agent for the gastrointestinal tract. The particles were administered to pigs perorally either suspended in water or mixed with food. The gastrointestinal tract structures were excellently depicted through a lowered signal intensity of their content in both T1 and T2 weighted images. Relatively large volumes with low particle concentration seemed to give a good contrast agent distribution, especially when the administration was extended over a period of time. Problems with artefacts and blurring in the images caused by a too high local concentration of the contrast agent should also be minimized by using low particle concentrations.

Animals↗