| 11. |
- Kölby, Lars, 1963, et al.
(författare)
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Somatostatin receptor subtypes, octreotide scintigraphy, and clinical response to octreotide treatment in patients with neuroendocrine tumors.
- 1998
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Ingår i: World journal of surgery. - 0364-2313. ; 22:7, s. 679-83
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Tidskriftsartikel (refereegranskat)abstract
- Several types of neuroendocrine tumor express high numbers of somatostatin receptors (sstr). We have compared the expression of sstr subtypes with the outcome of octreotide scintigraphy in patients with carcinoids and medullary thyroid carcinoma (MTC) in comparison with Hürthle cell tumors. The effect of sstr activation (octreotide treatment) on tumor markers was also studied in patients with disseminated carcinoid tumors. Six patients with carcinoid tumors (four midgut and two foregut), and three patients with thyroid tumors (one MTC, one Hürthle cell carcinoma, and one Hürthle cell adenoma) were studied. Octreotide scintigraphy visualized tumor sites in all nine patients. Macroscopic tumor was verified at these sites at subsequent surgical exploration. Using Northern blotting and subtype-specific riboprobes, sstr could be detected in all tumors examined. All five sstr subtypes were detected in most of the carcinoid tumors. All six carcinoids expressed sstr2. This was in contrast to the findings for the thyroid tumors analyzed, which also expressed several sstr subtypes but in some cases lacked expression of sstr2. This was also the case for normal thyroid tissue. Clinically, octreotide treatment of the patients with midgut carcinoid tumors resulted in palliation of hormonal symptoms accompanied by a significant reduction of urinary 5-HIAA levels (28-71%). These results indicate that carcinoid tumors frequently express all five sstr subtypes. The thyroid tumors also expressed multiple sstr but could lack expression of sstr2. Nevertheless, these tumors were visualized by octreotide scintigraphy, indicating that sstr2 expression is not a prerequisite for tumor imaging.
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| 12. |
- Boegård, Torsten
(författare)
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Radiography and bone scintigraphy in osteoarthritis of the knee: comparison with MR imaging
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim was to compare radiography of the tibiofemoral joint (TFJ) and the patellofemoral joint (PFJ), as well as bone scinigraphy with MR imaging in middle-aged individuals with chronic knee pain in the format of a prospective study of knee osteoarthritis. Individuals aged 35-54 years with chronic knee pain were identified. The prevalence of chronic knee pain was 15% (279/2000). Within this group of people, both knees in 61 randomly chosen persons, were examined with plain weight-bearing radiograms of the TFJ, standing axial radiograms of the PFJ and bone scintigraphy. One knee (the most painful at inclusion in the study) in each person was examined with MR imaging on a 1.0 T imager. Assessment of the minimal joint space (MJS) width in the PA view of the TFJ in weight-bearing examinations should be performed with equal weight on both legs and in semiflexion. MJS of 3 mm in the TFJ and MJS of 5 mm in the PFJ are limits in diagnosing joint-space narrowing (JSN) in the TFJ and the PFJ, respectively. There is a high prevalence of meniscal abnormalities within the narrowed compartments of the TFJ in comparison with those that were narrowed. With the presence of marginal osteophytes in the TFJ there is a high prevalence of MR-detected cartilage defects in the same joint whether JSN (MJS < 3 mm) is present or not. No such relationship, independent of MJS, was found between marginal osteophytes and cartilage defects in the PFJ. The agreement between increased bone uptake and MR-detected subchondral lesion was good. The agreement between increased bone uptake and MR-detected osteophytes or cartilage defects was in general poor. With the increased knowledge about interpreting weight-bearing PA radiograms of the TFJ and axial radiograms of the PFJ, these examinations will even in the future be valuable when evaluating knee pain. Further studies have to be done to evaluate if MR imaging has the same ability as bone scintigraphy to predict the progression of the OA process.
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| 13. |
- Wirestam, Ronnie
(författare)
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Nuclear magnetic resonance and microcirculation: The influence of pulsatile brain-tissue motion on measurements of intravoxel incoherent motion and assessment of haemodynamics using exo- and endogenous tracers
- 1997
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this project, the potential of magnetic resonance (MR) imaging and spectroscopy in studies of microcirculation and haemodynamics was evaluated. The spatial and temporal characteristics of human pulsatile brain-tissue movements in healthy individuals, relevant for the understanding of the cerebrospinal-fluid (CSF) circulation and the pathogenesis of hydrocephalus, were thoroughly investigated. Abnormal motion patterns in brain tissue and CSF were demonstrated in patients with intracranial tumours, and navigator echoes were shown to reduce motion artifacts in phase images. Intravoxel phase dispersion, caused by a spatial distribution of brain-tissue velocities, was shown to act as a source of uncertainty in gradient-sensitised MR imaging of intravoxel incoherent motion (IVIM). The diffusion coefficient was considerably overestimated if measured during inappropriate periods in the cardiac cycle, a finding which may also prove important in IVIM-encoded echo-planar imaging (EPI). Using IVIM-sensitive EPI, the perfusion fraction in patients with acute ischaemic stroke was shown to be considerably smaller in the infarct region than in normal tissue in the contralateral hemisphere. In a deuterium MR spectroscopy study, the D2O washout in animals, after intratissue injection, displayed a pronounced injection-volume dependence as well as a non-physiological component of signal decay. The reproducibility was reasonable in subcutaneous tissue, but rather poor in heterogeneous tumours. In a dynamic susceptibility-contrast MR imaging study, the first passage of an exogenous tracer (Gd-DTPA- BMA) was monitored in the normal human brain, and reasonable regional cerebral blood volume (rCBV) values were observed. The rCBV and the perfusion fraction in white matter showed a promising tendency to correlate. Finally, functional MR imaging (fMRI) studies of cortical activation were initiated in a typical clinical environment, and it was verified that cortical activation is observable both at 1.0 T and 1.5 T. Investigations of the field-strength dependence might, to some extent, provide information on the origin of the fMRI contrast in gradient-echo imaging.
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| 14. |
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| 15. |
- Berglund, Jan, et al.
(författare)
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Rapid increase in volume of the remnant after hemithyroidectomy does not correlate with serum concentration of thyroid stimulating hormone
- 1998
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Ingår i: European Journal of Surgery. - : Oxford University Press (OUP). - 1102-4151 .- 1741-9271. ; 164:4, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the effect of postoperative thyroxine on the volume of the thyroid remnant after lobectomy for benign nontoxic goitre. DESIGN: Prospective, randomised study. SETTING: University hospital, Sweden. SUBJECTS: 50 consecutive patients who underwent lobectomy for benign non-toxic goitre. INTERVENTIONS: Patients were randomised postoperatively to take thyroxine 0.1 mg or placebo daily. MAIN OUTCOME MEASURES: The median volume of the remaining thyroid lobe measured by ultrasound. Serum concentrations of thyroxine, triiodothyronine (T3) and thyroid stimulating hormone (TSH) were measured preoperatively and 1, 3, 6, 12 months postoperatively. RESULTS: The median volume of the remaining lobe had increased significantly compared with preoperatively by 1 month postoperatively by 30% in the thyroxine group and 25% in the placebo group (p < 0.01). The difference between the groups was not significant. After the first month the volume did not change significantly. In the thyroxine group, the TSH concentration was unchanged and the thyroxine concentration increased significantly throughout the study. In the placebo group there was a significant increase in TSH concentration and a significant decrease in that of thyroxine at all follow-up examinations. CONCLUSIONS: There is a significant increase in the volume of the remaining thyroid 1 month after lobectomy that persisted throughout the first year. Thyroxine given in a dose that kept the serum TSH concentration at the same level as preoperatively did not seem to influence volume changes; consequently we consider that these are caused by factors other than TSH.
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| 16. |
- Bornmyr, Siv
(författare)
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Laser Doppler Flowmetry and Imaging: Methodological Studies
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Laser Doppler flowmetry (LDF) and laser Doppler imaging (LDI) are modern methods for non-invasive and continuous assessment of skin blood flow. The techniques are based on the phenomenon that monochromatic light transilluminating a perfused tissue is spectrally broadened owing to scattering by moving blood cells. In this study, methodological aspects of the two methods are presented. LDF was used in healthy subjects and in patients with peripheral arterial occlusive disease to determine the skin perfusion pressure by measuring the flow cessation external pressure (FCEP). With a normal ankle index, FCEP is lower than the ankle pressure and with a decreased ankle index, FCEP correlates with the ankle pressure. LDF and LDI were used in healthy subjects to investigate the mechanisms of skin blood flow regulation particularly related to the sympathetic nervous system, and to elucidate the interrelation between skin temperature and skin blood flow. We found that LDF and LDI can be used to monitor sympathetic vasoconstriction. The interrelation between skin temperature and skin blood flow as measured with the laser Doppler techniques is ambiguous. LDI was used to examine the pathophysiological background to cold intolerance experienced by patients with traumatic division of the ulnar artery. Although ligation of the ulnar artery causes reduced finger skin blood flow, cold intolerance cannot be attributed solely to alterations in blood flow. A clinical test based on LDI was developed for routine assessment of the sympathetic vasoconstrictor response (VAC). Healthy subjects as well as patients with sympathectomy due to hand hyperhidrosis underwent the test procedure. A VAC nomogram was constructed in relation to which the patients with sympathectomy showed a clearly attenuated response. Finally, LDI was combined with digital photography to facilitate the interpretation of blood flow profiles in relation to clinical signs, and the device proved to be of clinical value.
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| 17. |
- Hochbergs, Peter
(författare)
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Magnetic Resonance Imaging in Legg-Calvé-Perthes Disease
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aims of this study were: to compare the cartilaginous outline of the femoral head obtained on arthrograms with those on MR images and to correlate it to the bony head outlines on conventional radiograps; to study early, postoperative cartilaginous and bony remodeling of the femoral head, after proximal femoral varus derotation extension osteotomy, with MR imaging and conventional radiography; to describe signal abnormalities on MR images in the femoral epiphysis, their location, extent and restitution over time; to evaluate the degree and persistence of synovitis in the hip joint by MR imaging; to analyze the metaphyseal histology and to correlate it to the signal intensity on the MR images in the corresponding biopsy region. Results and conclusions: MR imaging and arthrography define the shape of the femoral head cartilage equally well. The bony head outlines on conventional radiographs do not adequately reflect the cartilaginous outlines of the femoral head obtained by MR imaging. There is an early, postoperative, continuous, spherical remodeling following proximal femoral varus derotation extension osteotomy. The cartilaginous remodeling as seen in MR images appears earlier than the bony remodeling seen on conventional radiographs. In the coronal plane on MR images, the pathological signal is lowest in the central portion of the necrotic epiphysis. In addition, hips with advanced disease show signal changes in the peripheral regions. Repair processes start from the periphery, slowly progressing towards the center of the necrotic epiphyseal region. Signal changes persist in the period 3-6 years after diagnosis. All diseased hips have synovitis initially. The degree of synovitis on MR images in the inferomedial aspect of the hip joint correlates to the extent of the epiphyseal necrosis seen in conventional radiography or MR imaging. Synovitis is most intense initially in the disease, slowly decreasing, but persisting for several years, in some hips for more than 5 years after diagnosis. There is no correlation between the uniform histological patterns of consistent morphologic changes of the metaphysis and MR imaging with a low-field unit.
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| 18. |
- Åkeson, Per
(författare)
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Gadodiamide injection for Enhancement of MRI in the CNS. Applications, dose, field and time dependence.
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aims of the study The aims of this study using Gadodiamide injection were to investigate: · Whether Gadodiamide injection was comparable to Gd-DTPA for the enhancement of CNS lesions. · The contrast effect at different field strengths. · The effective time-window for the enhancement of blood-brain barrier damage. · The relations between the concentration of contrast agent and enhancement in phantoms, and to correlate the results to doses given to patients. · The use of a higher dose in two important clinical problems; the detection of metastases in the brain, and the evaluation of patients with failed back surgery syndrome (patients with recurrent pain after surgery for lumbar disc herniation). Results and conclusions · Gadodiamide injection was comparable to Gd-DTPA with regard to both safety and diagnostic efficacy in the CNS. · The contrast effect of Gadolinium contrast agents is higher at 1.5 T than at 0.3 T both in phantoms and patients with a maximum ratio (signal lesion / signal grey matter) more than 50% higher at 1.5T. · To achieve high contrast effect, heavily T1-weighted images are also important at both field strengths, as prolonging the repetition time from 400 ms to 600 ms reduced the ratio by 15-45% depending on concentration. · The effective time-window for imaging of blood-brain barrier damage is between 2-5 and 25-30 minutes after injection and several scans can be performed without loss of enhancement. · To provide maximum detectability of blood-brain-barrier-damage in patients with brain lesions, higher doses of Gd contrast media should be useful, as the doses used clinically today do not utilize the maximum contrast effect, either at high or low field strength. However, higher doses are more important at low field strengths because the contrast effect is lower than at high field strengths. · High-dose (0.3 mmol/kg b.w.) contrast-enhanced T1-weighted spin-echo MRI with Gadodiamide injection allowed detection of significantly (p<<0.01) more and smaller metastases than standard-dose (0.1 mmol/kg b.w.) MRI at 0.3 T. High-dose contrast-enhanced MRI with Gadodiamide injection is an efficient way to improve the detection of brain metastases. This should also be true for blood-brain barrier disruptions of other causes. · High-dose (0.3 mmol/kg b.w.) contrast-enhanced T1-weighted spin-echo MRI at 0.3T did not increase the diagnostic information in patients with recurrent pain after surgery for lumbar disc herniation compared to standard-dose (0.1 mmol/kg b.w.) MRI. The high dose images were considered more informative than the standard dose images when compared in pairs but gave no additional or different diagnostic information when evaluated separately.
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| 19. |
- Ohlsson, Tomas G
(författare)
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A clinical positron emission tomography facility : 2-¹⁸FDG studies : development and results
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Positron emission tomography (PET) is a tracer technique used for quantitative in vivo studies of physiological and biochemical processes. Because of the use of positron-emitting radionuclides such as 11-C, 13-N, 15-O and 18-F, which are isotopes of the biologically ubiquitous elements, it is possible to label radiopharmaceuticals which trace biochemical processes precisely. In order to be able to utilize these useful positron-emitting radiopharmaceuticals without state-of-the-art PET systems, it is interesting to develop alternatives to standard commercial PET facilities. Two different types of nuclear physics research accelerators have been used for the production of [18-F]fluoride, and the isotope produced has been used for radiolabelling of 2-[18F]fluoro-2-deoxy-D-glucose (2-18FDG). A rotating PET scanner, based on two scintillation camera heads, has been developed and used for human 2-18FDG studies. The suitability of an energy window in the Compton region for imaging 511 keV photons in scintillation camera systems has been evaluated. A new simplified method of normalizing clinical 2-18FDG PET results has been developed and validated, using erythrocytes as a reference tissue, requiring only one blood sample in the middle of the PET scan to calculate the integrated 2-18FDG input function with an accuracy better than ± 8%. An investigation using 2-18FDG PET to monitor the effect of therapy in advanced head and neck cancer patients has been performed. We found that low initial metabolic rate of glucose (MRgl ) predicted a complete local response. The second PET examination gave no further information for this group. In the group of primary tumours and lymph node metastases representing a combination of high initial MRgl and a small decrease in MRgl at the second PET examination, the outcome was unfavourable. An accurate normalization of 2-18FDG uptake was essential to evaluate the results of this study.
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| 20. |
- Ahlman, Håkan, 1947, et al.
(författare)
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The relevance of somatostatin receptors in thyroid neoplasia.
- 1997
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Ingår i: The Yale journal of biology and medicine. - 0044-0086. ; 70:5-6, s. 523-33
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 111In-octreotide scintigraphy in patients with persistent medullary thyroid carcinoma (MTC) visualized tumors in about half of the surgically explored sites. Tumor visualization correlated with rapid tumor growth and large tumor volume as judged from calcitonin levels. The 111In concentration ratio between tumor (T) and blood (B) in surgically excised lymph node metastases of MTC showed a large variation, with low values for microscopic and high values for macroscopic metastases in individual patients. Three cases of MTC, Hürthle cell adenoma and papillary thyroid cancer are reported with preoperative scintigraphy, T/B ratios and Northern analyses of the surgical biopsies. Visualization of tumors was possible in the absence of sstr2 (the high affinity receptor for octreotide) with the exception of microscopic tumor growth. T/B values in the patient with Hürthle cell adenoma were similar to those found in the contralateral thyroid lobe with goitre. The relatively high uptake of 111In in benign thyroid conditions probably limits the use of octreotide scintigraphy in the diagnosis of primary tumors. The technique has certain advantages over radioiodine scintigraphy after the surgical treatment of thyroid tumors: no need for withdrawal of thyroxin substitution; a possibility to diagnose metastases of tumors that do not concentrate radioiodine (MTC, Hürthle cell cancer); and complementary information about metastatic sites of non-medullary thyroid cancer (papillary and follicular tumors).
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