| 1. |
|
|
| 2. |
- Wängberg, Bo, 1953, et al.
(författare)
-
Intraoperative detection of somatostatin-receptor-positive neuroendocrine tumours using indium-111-labelled DTPA-D-Phe1-octreotide.
- 1996
-
Ingår i: British journal of cancer. - 0007-0920. ; 73:6, s. 770-5
-
Tidskriftsartikel (refereegranskat)abstract
- After injection of 111In-labelled DTPA-D-Phe1-octreotide, intraoperative tumour localisation was performed using a scintillation detector in 23 patients with neuroendocrine tumours. Count rates from suspect tumour lesions and adjacent normal tissue were expressed as a ratio before (Rin situ) and after (Rex vivo) excision. 111In activity concentration ratios of tumour tissue to blood (T/B) were determined in a gamma counter. In patients with midgut carcinoids, (all scintigraphy positive), false Rin situ recordings were found in 4/29 macroscopically identified tumours. T/B ratios were all high (27-650). In patients with medullary thyroid carcinomas (eight out of ten scintigraphy positive), misleading Rin situ results were found in 4/37 macroscopically identified tumours. T/B ratios were lower (3-39) than those seen in midgut carcinoids. Two out of four patients with endocrine pancreatic tumours had positive scintigraphy, reliable intraoperative measurements and very high T/B ratios (910-1500). One patient with a gastric carcinoid had correct measurements in situ and ex vivo with high T/B ratios (71-210). In situ measurements added little information to preoperative scintigraphy and surgical findings using the present detection system. Rex vivo measurements were more reliable. The very high T/B ratios seen in midgut carcinoids and some endocrine pancreatic tumours would be favourable for future radiation therapy via somatostatin receptors.
|
|
| 3. |
- Lindh, Mats, et al.
(författare)
-
Endovascular stent-anchored aortic grafts: a comparison between self-expanding and balloon-expandable stents in minipigs
- 1996
-
Ingår i: Journal of Endovascular Surgery. - 1074-6218. ; 3:3, s. 284-289
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To study endovascular graft attachment with self-expanding Gianturco Z-stents and balloon-expanded Palmaz stents and the effect of these devices on the renal ostia. METHODS: Ten stent-grafts were constructed, 5 with Gianturco Z-stents and 5 with Palmaz stents. The endografts were implanted under fluoroscopic guidance into the abdominal aorta of 10 pigs so that the uncovered portion of the proximal stent extended over the renal artery orifices. Distal aortic blood pressure and flow were measured before and after graft placement and 1 hour postprocedure. The aorta was then exposed surgically, and the central portion of the stent-graft was inspected through an aortotomy to assess perigraft leakage. RESULTS: Stent-graft implantation was accurate and hemostatic in all cases, despite longitudinal folding of the graft due to oversizing. However, transverse folds produced pressure gradients (> 15 mmHg) between the ends of the graft in two cases. In another case, a pressure gradient resulted from partial thrombosis of the graft. In two cases, renal artery occlusion and thrombosis occurred due to coverage by the graft material. In two other animals, one of the renal arteries was entirely uncovered by a stent. The remaining 16 renal arteries were covered by the proximal stent but not the graft, as intended. One (6.25%) of these arteries thrombosed, but the remainder were grossly patent when the animals were sacrificed at 1 hour. CONCLUSIONS: Both Palmaz and Gianturco Z-stents produced hemostatic endovascular graft attachment, even in the presence of moderate graft oversizing. The risk of acute renal artery occlusion from juxtarenal stenting does not appear to be prohibitive, but longer term observations are needed.
|
|
| 4. |
- Fjälling, M, et al.
(författare)
-
Systemic radionuclide therapy using indium-111-DTPA-D-Phe1-octreotide in midgut carcinoid syndrome.
- 1996
-
Ingår i: Journal of nuclear medicine : official publication, Society of Nuclear Medicine. - 0161-5505. ; 37:9, s. 1519-21
-
Tidskriftsartikel (refereegranskat)abstract
- A 55-yr-old woman with a midgut carcinoid syndrome due to metastatic spread of an ileal tumor to the liver, paraortic and mediastinal lymph nodes and to the skeleton was given systemic radionuclide therapy with 111In-DTPA-D-Phe1-octreotide. Before therapy, dosimetric calculations were performed on whole-body scintigraphs and 111In retention was shown to be long-lasting. Excretion was mainly seen during the first 24 hr after injection; thereafter whole-body retention remained stationary at 30%. Indium-111 activity in tumor biopsies and blood was measured using a gamma counter. Very high tumor-to-blood ratios were obtained: 150 for the primary tumor and 400-650 for liver metastases, which further justified radiation therapy. Indium-111-DTPA-D-Phe1-octreotide treatment was given on three separate occasions (3.0, 3.5 and 3.1 GBq) 8 and 4 wk apart. After each therapy, the patient experienced facial flush and pain over the skeletal lesions followed by symptomatic relief, even though no objective tumor regression was found radiologically after 5 mo. After initiation of octreotide treatment, there was a 14% reduction of the main tumor marker, urinary 5-HIAA. After three subsequent radionuclide therapies, there was a further 31% reduction of 5-HIAA levels. No adverse reactions, other than a slight decrease in leukocyte counts, were seen. The mean absorbed radiation dose after the three treatments was estimated to be about 10-12 Gy in liver metastases and 3-6 Gy in other tumors, depending on the size and location of the metastases. Assuming internalization of 111In into tumor cells and a radiobiological effect from short range Auger and conversion electrons, there might be a therapeutic effect on the tumor.
|
|
| 5. |
- Ohlsson, Tomas G
(författare)
-
A clinical positron emission tomography facility : 2-¹⁸FDG studies : development and results
- 1996
-
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.
|
|
| 6. |
- Åkeson, Per
(författare)
-
Gadodiamide injection for Enhancement of MRI in the CNS. Applications, dose, field and time dependence.
- 1996
-
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.
|
|
| 7. |
|
|
| 8. |
- Blad, Börje, et al.
(författare)
-
Impedance spectra of tumour tissue in comparison with normal tissue; a possible clinical application for electrical impedance tomography
- 1996
-
Ingår i: Physiological Measurement. - 0967-3334. ; 17, s. 105-115
-
Tidskriftsartikel (refereegranskat)abstract
- Electrical characteristics of living tissues have been investigated for a long time in the search for further methods to complement the traditional investigations of pathology and physiology. Tumour tissue has been shown to exhibit a larger permittivity and conductivity than normal tissues. This might be associated with the fact that tumour cells have a higher water content and sodium concentration than normal cells, as well as different electrochemical properties of their cell membranes. To our knowledge only a few contributions on this subject have been published. This study describes an additional application on measurements of the complex impedance of tumour and normal tissues, in order to compare the impedance features of the two tissue types. The tissue sample is placed in a measuring cell in which the temperature is controlled. The measuring cell is connected to an impedance meter able to measure the complex impedance in terms of real and imaginary part curves for frequencies from 1.5 kHz to 700 kHz. The four-electrode principle is used with the current injected by the outer electrodes and the voltage difference measured between the inner electrodes. The current can be altered up to 1 mA. The instrument can be calibrated with known resistance and capacitance networks connected to the input of the instrument in order to minimize the measurement errors. The calibration routine uses a polynomial adaptation and can be applied interactively. Measurements performed by the instrument show promising results. Preliminary results show that this method can be extended to a new application for detection of tumour tissue by electrical impedance tomography (EIT).
|
|
| 9. |
|
|
| 10. |
|
|
