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Biomedical subjects

S A Larsson

Publications and source records attributed to S A Larsson.

At least 19 recordsLinked to original sources
PubMed1992

Diagnostic accuracy of lightscanning and mammography in women with dense breasts.

The diagnostic accuracy of lightscanning and mammography in 610 breasts with mammographically dense parenchymal patterns was investigated. Lightscanning identified 31 out of 36 cancers and mammography 32. Lightscanning and mammography were in agreement in 28 cases of cancer. One noninvasive lobular carcinoma was not identified by either modality. Four cancers were not correctly identified with lightscanning alone and 3 cancers with mammography alone. Of the 574 breasts without cancer, lightscanning falsely denoted 101 (18%) as possibly being cancerous (false-positives). The corresponding figure for mammography was 25 (4%). Thus, lightscanning, as performed in this study, has the same sensitivity as mammography in detecting cancer in mammographically dense breasts. However, its usefulness is limited by a low predictive value of a positive test (high rate of false-positives).

Adolescent↗
PubMed1991

NCQ 298, a new selective iodinated salicylamide ligand for the labelling of dopamine D2 receptors.

NCQ 298 ((S)-3-iodo-N-[(l-ethyl-2-pyrrolidinyl)methyl]-5,6- dimethoxysalicylamide) has an iodine substituent. We have labelled NCQ 298 with 123I and 125I, and used the radioligands as tracers in receptor studies in vitro, in vivo in autoradiography and in SPECT studies on Cynomolgus monkeys. [125I]NCQ 298 bound in vitro to a single binding site with a KD = 19 pM. NCQ 298 has thus a 10-fold higher affinity for the dopamine D2 receptors than the corresponding des-5-methoxy compound FLA 961 (IBZM), previously used in SPECT studies. The binding of [125I]NCQ 298 was entirely reversible (T1/2 = 17.5 min at 37 degrees C). Autoradiographical studies in vitro on rat and monkey brain tissue sections showed a distinct binding in caudate-putamen, nucleus accumbens, substantia nigra, and in layer 5 of the cerebral cortex. In vivo binding studies in mice showed a ratio of 10 between [125I]NCQ 298 binding in striatum and cerebellum. Binding was displaced by the selective dopamine D2 receptor antagonist raclopride. In SPECT studies with [123I]NCQ 298 in two Cynomolgus monkeys, radioactivity accumulated in the basal ganglia. The measured striatum to cerebellum ratio was about 15 after 3 h. A monkey brain phantom was constructed for the determination of conversion factors from pixel events to actual radioactivity. The resulting, corrected striatum to cerebellum ratio obtained was 30. After administration of 12 mg raclo-pride to one of the monkeys there was a substantial decrease in striatal radioactivity. [125I]NCQ 298 is a suitable ligand for the labelling of dopamine D2 receptors in vitro and in vivo. The specific properties of [123I]NCQ 298 suggest that this compound is a useful ligand for quantitative SPECT studies of dopamine D2 receptors in man.

Animals↗
PubMed1990

Lightscanning versus mammography for the detection of breast cancer in screening and clinical practice. A Swedish multicenter study.

State of the art lightscanning of the breast was tested against mammography in 2568 women in a Swedish multicenter study. The study was in two parts. One was in women with symptoms from the breasts (the clinical study) comprising 3178 examined breasts with 198 cancers; the other in asymptomatic women (the screening study) comprising 1909 examined breasts with 126 cancers. In women with symptoms from the breasts, lightscanning did not contribute to clinical examination and mammography. In the screening situation, it was poor to pick up small cancers. Mammography alone falsely diagnosed cancer in 6.9% of the patients whereas lightscan falsely diagnosed cancer in 19.1%. Lightscan was not better than mammography in young women. The study shows that lightscanning in its current form is inferior to standard mammography.

Adult↗
PubMed1989

Some physical factors influencing the accuracy of convolution scatter correction in SPECT.

Some important physical factors influencing the accuracy of convolution scatter correction techniques in SPECT are presented. In these techniques scatter correction in the projection relies on filter functions, QF, evaluated by Fourier transforms, from measured scatter functions, Qp, obtained from point spread functions. The spatial resolution has a marginal effect on Qp. Thus a single QF can be used in the scatter correction of SPECT measurements acquired with the low energy high resolution or the low energy general purpose collimators and over a wide range of patient-collimator distances. However, it is necessary to examine the details of the shape of point spread functions during evaluation of Qp. QF is completely described by scatter amplitude AF, slope BF and filter sum SF. SF is obtained by summation of the values of QF occupying a 31 x 31 pixels matrix. Regardless of differences in amplitude and slope, two filter functions are shown to be equivalent in terms of scatter correction ability, whenever their sums are equal. On the basis of filter sum, the observed small influence of ellipticity on QF implies that an average function can be used in scatter correcting SPECT measurements conducted with elliptic objects. SF is shown to increase with a decrease in photon energy and with an increase in window size. Thus, scatter correction by convolution may be severely hampered by photon statistics when SPECT imaging is done with low-energy photons. It is pointless to use unnecessarily large discriminator windows, in the hope of improving photon statistics, since most of the extra events acquired will eventually be subtracted during scatter correction. Regardless of the observed moderate reduction in SF when a lung-equivalent material replaces a portion of a water phantom, further studies are needed to develop a technique that is capable of handling attenuation and scatter corrections simultaneously. Whenever superficial and inner radioactive distributions coexist the observed reduction of SF close to the phantom surface indicates that scatter correction of such distributions has to rely on two distinct filter functions. Corrections based on a surface function produce accurate results in the superficial region, while the central distributions are substantially overestimated. Surface radioactive distributions introduce appreciable errors in the determination of central distributions when corrections are based on central filter function. This function introduces a reduction of about 40% in the measured surface concentration.

Humans↗
PubMed1988

Comparison of gastric aspiration and HIDA scintigraphy in detecting fasting duodenogastric bile reflux.

Gastric aspiration and HIDA scintigraphy have been compared to assess duodenogastric bile reflux. Gastric aspiration was performed on two separate occasions with a total examination time of 3 h. The highest 1-h output and the highest concentration of bile acids were recorded. HIDA scintigraphy was carried out for 90 min after an injection of 60 MBq 99mTc-dimethyl-iminodiacetic acid (HIDA). Forty-six patients with different gastrointestinal disorders were studied; 24 patients were positive and 13 negative in both tests. Accordingly, the methods agreed in 37 to 46 patients (80.4%). It is concluded that gastric aspiration is as reliable as HIDA scintigraphy to assess fasting bile reflux.

Adult↗
PubMed1987

Retrospective evaluation of single photon emission computed tomography of the liver.

Retrospective analysis, including indications for examination, of 335 consecutive liver examinations of adults with single photon emission computed tomography performed at the Karolinska Hospital during the first eight months of 1981 has been carried out. 85.1% of the investigations were performed in tumour patients. This group underwent retrospective evaluation specifically regarding space occupying lesions of the liver with a minimum follow-up time of 3 years. An adequate follow-up of 87.4% was achieved. The study showed a sensitivity of 82.7% and a specificity of 93.9%. The positive and negative predictive values were 78.2% and 95.4%, respectively. 4.4% of the examinations were regarded as equivocal. Compared to previously reported values for planar liver scintigraphy derived from several different studies, the tomographic technique produced no increase of specificity or positive predictive value but a higher total accuracy, probably due to better clarification of the hepatic anatomy. The false positive, false negative and equivocal diagnoses were analysed and reported.

Adolescent↗
PubMed1987

Generalized scatter correction method in SPECT using point scatter distribution functions.

A new two-dimensional (2-D) scatter correction technique in single photon emission computed tomography (SPECT) based on convolution or frequency filtering with a 2-D scatter distribution function is described. A scatter distribution function of the form A exp(-Br), has been derived from measurements of a point source in a water phantom. Both the amplitude A and the slope B of this function, were approximately invariant with source position except near phantom surface. The accuracy of the 2-D correction technique was compared with that of the previous one-dimensional (1-D) scatter correction technique. As could be expected the latter technique was shown to be less accurate due to its dependence on axial distribution of radioactivity. Phantom SPECT studies showed a clear superiority of the 2-D over the 1-D scatter correction in quantitative imaging. Images derived from clinical studies of regional bloodflow with 99mTc-HM-PAO and liver uptake showed significant contrast improvement by both techniques.

Scattering, Radiation↗
PubMed1986

Radionuclide cisternography and computed tomography in 30 healthy volunteers.

Radiological assessments of patients with symptoms of impaired cerebrospinal fluid (CSF) circulation are usually based on observations of anatomical and functional alterations using computed tomography (CT) and radionuclide cisternography (RC). In order to define criteria of normality for these two techniques, 30 healthy volunteers have been studied. In the studies of CSF flow the radiopharmaceutical 99mTc-DTPA was used and single photon emission computed tomography (SPECT) was performed as a complement to planar scintigraphy. In 16 of the 30 volunteers the pattern of CSF flow was normal according to conventional criteria. In these subjects the radioactivity was symmetrically located over the parietal cortex 24 h after the injection and no intraventricular activity could be recorded. In 11 (41%) of the subjects, radioactivity could be observed in the lateral ventricles 6 h after injection. One of these subjects had a reflux of radioactivity into the lateral ventricles. The intraventricular radioactivity persisted for at least 24 h. This subject also had signs of obstruction of CSF flow over the convexities. Asymmetric distribution of radioactivity within the CSF spaces was observed in the images obtained after 6 but not 24 h in two cases. One of those also demonstrated transient intraventricular radioactivity. The results of the computed tomography were interpreted to be normal in 19 (63%) of the 30 volunteers. One subject had an asymmetric ventricular system. The CT scans of six subjects (20%) differed considerably from the others as they displayed wide cortical or vermian sulci at the borderline of normal variations. The case with the pathological RC belonged to the group of subjects who had wide sulci.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Polyclonal and monoclonal anti-CEA antibodies in immunolocalization of colorectal cancer.

Antibodies to carcinoembryonic antigen (CEA) from sheep and monkey were immunoadsorbent purified. Mouse monoclonal antibody (MAb) anti-CEA I-38S1 and Fab fragments of this antibody were prepared from mouse ascitic fluid. The IgG preparations were labelled with 123I or 131I, the Fab fragments with 131I. The antibody reactivity was unchanged after labelling. Patients with advanced colorectal carcinomas received an intravenous injection of 50-200 MBq 123I or 30-160 MBq 131I coupled to 250-500 micrograms antibody or antibody fragment. Patient examinations were performed using emission tomography (SPECT) and/or conventional gamma camera scintigraphy. The specific localization of labelled anti-CEA to tumor was compared to known tumor localized by CAT-scan, other x-ray methods or laparotomy, 50% of known tumors were accurately localized with sheep anti-CEA. In contrast, 70-80% of known tumor sites were correctly localized with polyclonal monkey anti-CEA antibodies, with monoclonal anti-CEA antibodies or with Fab fragments of the latter. A few previously unknown tumors were detected.

Antibodies, Monoclonal↗
PubMed1986

A new method for granulocyte labeling with technetium-99m: preliminary results in abscess detection.

A new method for 99mTc-labeling of granulocytes for clinical routine use has been developed. The labeling is simple to perform by means of a kit of radiopharmaceutical quality, utilizing dihydroxy-benzoic acid. Pretinning techniques are avoided. The technique has been applied clinically in 15 patients with indications of intra-abdominal abscess. In six patients, [99mTc]granulocyte scintigraphy at 3 hr and/or 24 hr after i.v. administration, correctly depicted the abscess, as verified by subsequent surgery. In the remaining patients, who were negative at surgery or recovered without operation, all scans were negative.

Abdomen↗
PubMed1985

Specific considerations in the interpretation of single-photon-emission computed tomography of the normal liver.

In our hospital, single-photon-emission computed tomography (SPECT) has been routinely used instead of conventional scintigraphy in the examination of the liver and spleen in more than 3,000 patients. This technique is preferred because it provides more detailed information and better contrast resolution than planar views. However, using the SPECT technique, normal variations in liver anatomy are more apparent, and certain cases--in particular those with a wide main lobar fissure combined with a prominent gall bladder fossa as well as cases with a large hilus--may erroneously be interpreted as having a focal lesion. In order to facilitate the interpretation of SPECT examinations of the liver, the most common difficulties and pitfalls arising from normal variations in hepatic anatomy, indentations caused by surrounding organs and partial-volume effects are described and compared with the findings of corresponding transmission computed tomograms.

Colloids↗
PubMed1985

Life expectancy of Swedish haemophiliacs, 1831-1980.

Life expectancy of Swedish haemophiliacs has been estimated for the period 1831-1980. The data were derived from 948 haemophiliacs of whom 580 survived throughout 1980. Applying standard demographic techniques, median life expectancy of patients with severe haemophilia was found to have increased fivefold, from a mere 11 years during the period 1831-1920 to 56.8 years during 1961-80. The corresponding estimates for patients with moderate haemophilia were 27.5 and 71.5 years, respectively. The limited data on patients with mild haemophilia did not indicate any significant improvements in mortality. From the beginning of this century to 1980 median life expectancy for Swedish males increased from 61.7 years to 75.6 years, an increase of 23%. Analysing the last 12 years of the study (1969-80), death rates for patients with severe haemophilia below the age of 45 were not much different from those of Swedish males in the population as a whole. The investigation implies that the mortality of haemophiliacs in Sweden is approaching that of the total male population.

Adolescent↗
PubMed1979

Surgery in von Willebrand's disease.

Fifty-eight major surgical procedures were performed in 38 patients with von Willebrand's disease (VWD), one of the most common of the inheritable hemorrhagic disorders. Specific treatment with fraction I-0, (AHF-Kabi) in addition to a fibrinolytic inhibitor, was given to all patients. The effect of the treatment was checked by measuring the Duke bleeding time and factor VIII:C level. A marked difference between hemophilia and VWD from a surgical point of view is demonstrated. While most of the surgery in hemophiliacs is performed for severe joint deformities, contractures and blood cysts, surgery in VWD is mostly general surgery, often necessitated by massive hemorrhages from mucous membranes.

Adolescent↗
PubMed1977

Surgery of hemophiliacs--20 years' experience.

Seventy-seven hemophilic patients of type A or type B were subjected to a total of 108 major surgical procedures mainly in the field of general surgery, orthopedic surgery, or neurosurgery. The principles for the substitution therapy in the different types of procedures and different types of hemophilic diseases are described, as well as the indications for surgery and the surgical technique. The importance of prolonged substitution therapy postoperatively to avoid late hematoma, particularly in patients with severe hemophilia undergoing major surgery, is stressed. With this type of management there has been no increased intraoperative hemorrhage, and very few cases of late hematoma formation. By combining the substitution therapy with immunosuppression, it has been possible to operate also on patients with inhibitors against factor VIII or IX. The rate of complications, particularly the incidence of hepatitis, has been low with the type of substitution given in this series of patients. It is concluded that major surgery can be carried out even in severe hemophilia without significantly increased risk. The handling of the substitution therapy, and the surgical judgment and technique, offers however, special problems, necessitating centralization of elective cases.

Adolescent↗