| 1. |
- Melhus, Håkan, et al.
(author)
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Use of novel bone biopsy system to study molecular effects of growth hormone in human bone : a pilot study
- 1999
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In: IUBMB Life - A Journal of the International Union of Biochemistry and Molecular Biology. - : Wiley. - 1521-6543 .- 1521-6551. ; 48:2, s. 175-178
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Journal article (peer-reviewed)abstract
- In this study, we have examined whether a novel bone biopsy system combined with reverse transcription-polymerase chain reaction (RT-PCR) or differential display PCR (ddPCR) can be used to detect specific mRNAs induced by growth hormone (GH) in human bone. In a 58-year-old man with complete GH deficiency as a result of empty sella, bone biopsies were taken before, and 5 and 24 h after administration of 24 recombinant human GH. Insulin-like growth factor binding protein-3 (IGFBP-3) mRNA levels in this patient, measured in a semiquantitative RT-PCR assay, increased about 40% 24 h after GH administration. This increase was not seen in a healthy control who did not receive GH, suggesting that the increase was an effect of GH rather than of the biopsy itself. Several differentially expressed mRNAs were detected by ddPCR. Thus, this pilot study suggests that our novel bone biopsy system may be suitable for in vivo studies of the molecular effects of substances with essential functions in human bone.
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| 2. |
- Örlefors, Håkan, et al.
(author)
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Positron emission tomography with 5-hydroxytryprophan in neuroendocrine tumors
- 1998
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In: Journal of Clinical Oncology. - 0732-183X .- 1527-7755. ; 16:7, s. 2534-2541
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Journal article (peer-reviewed)abstract
- PURPOSE: Carcinoid tumors, especially those of midgut origin, produce serotonin via the precursors tryptophan and 5-hydroxytryptophan (5-HTP). We have evaluated the usefulness of positron emission tomography (PET) with carbon-11-labeled 5-HTP in the diagnosis and treatment follow-up evaluation of patients with neuroendocrine tumors. PATIENTS AND METHODS: PET using 11C-labeled 5-HTP was compared with computed tomography (CT) in 18 patients (14 midgut, one foregut, one hindgut carcinoid, and two endocrine pancreatic tumors [EPT]). In addition, 10 of 18 patients were monitored with PET examinations during treatment. RESULTS: All 18 patients, including two with normal urinary 5-hydroxyindole acetic acid (U-5-HIAA), had increased uptake of 11C-labeled 5-HTP in tumorous tissue as compared with normal tissue. Liver metastases, as well as lymph node, pleural, and skeletal metastases, showed enhanced 5-HTP uptake and PET could detect more lesions than CT in 10 patients and equal numbers in the others. Tumor visibility was better for PET than for CT due to the high and selective uptake of 5-HTP with a high tumor-to-background ratio. Binding studies indicated an irreversible trapping of 5-HTP in the tumors. Linear regression analyses showed a clear correlation (r = .907) between changes in U-5-HIAA and changes in the transport rate constant for 5-HTP during treatment. CONCLUSION: PET with 11C-labeled 5-HTP demonstrated high uptake in neuroendocrine gastrointestinal tumors and thereby allowed improved visualization compared with CT. The in vivo data on regional tumor metabolism, as expressed in 11C-5-HTP uptake and transport rate, provided additional information over conventional radiologic techniques. The close correlation between the changes in 11C-5-HTP transport rate and U-HIAA during medical treatment indicates the potential of 11C-5-HTP-PET as a means to monitor therapy.
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| 5. |
- Ahlström, Håkan, et al.
(author)
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Overview of MnDPDP as a pancreas-specific contrast agent for MR imaging
- 1997
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In: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 38:4 Pt 2, s. 660-664
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Journal article (peer-reviewed)abstract
- PURPOSE: To describe and discuss previous and ongoing clinical and experimental studies with MnDPDP (Teslascan) as a pancreas-specific contrast agent for MR imaging. MATERIAL AND METHODS: All results, both experimental and clinical, applying MnDPDP as a pancreas-specific contrast agent for MR imaging, were collected. RESULTS: An increase of up to 100% in signal intensity was seen in normal pancreatic parenchyma, reaching its maximum approximately 25 min after the beginning of MnDPDP administration. Maximal enhancement was sustained for 4 h. Enhancement was only seen in the T1-weighted images. No enhancement was observed in tumours and an increase in contrast-to-noise of about 200% was obtained. The uptake of MnDPDP in pancreatitis compared with normal pancreatic parenchyma was decreased in an animal model. CONCLUSION: Improved depiction and demarcation of pancreatic tumours with MR imaging were obtained after administration of MnDPDP. MR imaging with and without MnDPDP might be valuable for staging of pancreatitis.
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| 6. |
- Ahlström, Håkan, et al.
(author)
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Pancreatic neuroendocrine tumors : diagnosis with PET
- 1995
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In: Radiology. - 0033-8419 .- 1527-1315. ; 195:2, s. 333-337
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Journal article (peer-reviewed)abstract
- PURPOSE: To evaluate the use of carbon-11-labeled L-dihydroxyphenylalanine (L-DOPA) and hydroxytryptophan (5-HTP) in the diagnosis of pancreatic endocrine tumors with positron emission tomography (PET). MATERIALS AND METHODS: Twenty-two consecutive patients with clinically and biochemically verified pancreatic endocrine tumors were examined with computed tomography (CT) and PET with L-DOPA alone (n = 16) or both C-11-L-DOPA and C-11-5-HTP (n = 6). RESULTS: Tumor uptake of L-DOPA was found in 11 patients, eight of whom had metastatic disease. Heterogeneity of tracer uptake was noted among different lesions in the same patient (ie, high uptake in some lesions and low uptake in others). Results in patients examined with both L-DOPA and 5-HTP correlated well, but the uptake levels of 5-HTP were higher in two of three patients with positive findings. In two additional patients, CT enabled detection of tumors not detected at PET. CONCLUSION: The current PET technique can be a valuable complement to CT in demonstration of functional pancreatic endocrine tumors, in particular, glucagonomas, but is less useful in detection of nonfunctional tumors.
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| 7. |
- Ahlström, Håkan, et al.
(author)
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Positron emission tomography in the diagnosis and staging of urinary bladder cancer
- 1996
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In: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 37:2, s. 180-185
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Journal article (peer-reviewed)abstract
- PURPOSE: Evaluation of positron emission tomography (PET) using (18)fl 18F-2-fluoro-2-deoxy-D-glucose (18FDG) and L-methyl-11C-methionine in the diagnosis and staging of urinary bladder carcinoma. MATERIAL AND METHODS: Twenty-three patients with biopsy-proven urinary bladder carcinoma were examined with PET after intravenous injection of 11C-methionine; 2 were also examined with 18FDG. The results from the PET investigations were compared with CT or MR findings and TNM classification before and after treatment. RESULTS: The urinary excretion of 18FDG prevented distinction of the primary tumour from the surrounding tracer. With 11C-methionine it was possible to detect 18/23 primary tumours. A trend was seen, suggesting that the higher the uptake values of 11C-methionine in the tumour, the greater the tumour stage. CONCLUSION: It is possible to visualize urinary bladder tumours larger than 1 cm in diameter with PET using (11)C-methionine, but the value of the method in the staging of the lesions is not superior to conventional methods.
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| 8. |
- Ahlström, Håkan, et al.
(author)
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Pulmonary MR angiography with ultrasmall superparamagnetic iron oxide particles as a blood pool agent and a navigator echo for respiratory gating : pilot study
- 1999
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In: Radiology. - 0033-8419 .- 1527-1315. ; 211:3, s. 865-869
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Journal article (peer-reviewed)abstract
- In nine healthy adult volunteers, pulmonary magnetic resonance angiography was performed with the blood pool agent NC100150 injection combined with respiratory gating with a navigator echo. With increasing doses of the contrast agent, higher signal intensities and vessel branch order visualization were achieved. No motion artifacts were seen. The blood pool agent NC100150 injection in combination with respiratory navigator gating permitted acquisition of high-quality MR angiograms of the pulmonary vasculature during continuous breathing.
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| 9. |
- Bergström, Mats, et al.
(author)
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In vivo demonstration of enzyme activity in endocrine pancreatic tumors : decarboxylation of carbon-11-DOPA to carbon-11-dopamine
- 1996
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 37:1, s. 32-37
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Journal article (peer-reviewed)abstract
- METHODS:We used PET to characterize the uptake and decarboxylation of 11C-L-DOPA in vivo in two patients with endocrine pancreatic tumors: one glucagonoma and one gastrinoma.RESULTS:With L-DOPA labeled with 11C in the beta position, in which the radioactive label follows the molecule through decarboxylation to dopamine, significant uptake was observed in the tumors. With L-DOPA labeled in the carboxyl group, in which the label is rapidly eliminated from the tissue as 11CO2 if decarboxylation takes place, an almost complete lack of uptake is noted.CONCLUSION:This study shows that, using selective position labeling, an in vivo action of enzymatic activity can be observed with PET and that significant decarboxylation occurs in the tested endocrine pancreatic tumors. Also, marked retention of radioactivity occurs after treatment with somatostatin analogs. It is hypothesized that this is a reflection of a reduction of exocytosis which is induced by this treatment.
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| 10. |
- Bjerner, Tomas, et al.
(author)
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3D surface rendering of images from multiple MR pulse sequences in the pre-operative evaluation of hepatic lesions
- 1998
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In: Acta Radiologica. - 0284-1851 .- 1600-0455. ; 39:6, s. 698-700
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Journal article (peer-reviewed)abstract
- Segmentation and reconstruction took 1-2 h. To be able to combine the volumes from the different data sets, certain criteria had to be fulfilled: a) the field of view had to be constant; b) the same volume had to be scanned every time which meant that the slice thickness and the number of slices could be adjusted as long as the volume covered was the same; and c) the positioning of each volume had to be identical between every scan. The resulting 3D reconstruction gave the surgeon a clear appreciation of the different lesions and their relation to the different liver segments in the pre-operative planning of hepatic resections.
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