| 1. |
- Aitken, Candice L., et al.
(author)
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Tumor localization and image registration of 18-FDG SPECT scans with CT scans
- 1999
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In: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 40:5, s. 290P-291P
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Journal article (peer-reviewed)abstract
- PURPOSE: The aim of this study was to determine the feasibility of registering routine clinical F-18 fluorodeoxyglucose (FDG) coincidence detection (CD) scans with computed tomographic (CT) scans for radiation treatment planning and case management. METHODS: F-18 FDG CD and chest CT scans, performed in 10 randomly selected patients with confirmed or possible adenocarcinoma of the lung, were evaluated. The quality of the matches was verified by comparisons of the center-to-center distance between a region of interest (ROI) manually drawn on the CT slice and warped onto the CD slice with an ROI drawn manually directly on the CD slice. In addition, the overlap between the two ROIs was calculated. RESULTS: All 10 F-18 FDG CD and CT scans were registered with good superimposition of soft tissue density on increased radionuclide activity. The center-to-center distance between the ROIs ranged from 0.29 mm to 8.08 mm, with an average center-to-center distance of 3.89 mm +/- 2.42 mm (0.69 pixels +/- 0.34 pixels). The ROI overlap ranged from 77% to 99%, with an average of 90% +/- 5.6%. CONCLUSIONS: Although the use of F-18 FDG CD shows great promise for the identification of tumors, it shares the same drawbacks as those associated with radiolabeled monoclonal antibody SPECT and ligand-based positron emission tomographic scans in that anatomic markers are limited. This study shows that image registration is feasible and may improve the clinical relevance of CD images.
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| 2. |
- Andersson, Jesper L, et al.
(author)
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A method for coregistration of PET and MR brain images
- 1995
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 36:7, s. 1307-1315
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Journal article (peer-reviewed)abstract
- Combining MRI morphological data with functional PET data offers significant advantages in research as well as in many clinical situations. Automatic methods are needed, however, to coregister the data from the two modalities.METHODS:Simulated PET images were created by simple and automatic segmentation of MR images followed by the assignment of different uptake values to various tissue types. The simulated PET images were registered to actual PET images using a pixel-by-pixel, PET-PET registration method. The transformation matrix was then applied to the MR images. The method was used to register MRI data to PET transmission scans and emission scans obtained with FDG, nomifensine and raclopride. Validation was performed by comparing the results to those obtained by matching internal points manually defined in both volumes.RESULTS:Emission and transmission PET images were successfully registered to MR data. Comparison to the manual method indicated a registration accuracy on the order of 1-2 mm in each direction. No difference in accuracy between the different tracers was found. The error sensitivity for the method's assumptions seemed to be sufficiently low to allow complete automation of the method.CONCLUSION:We present a rapid, robust and fully automated method to register PET and MR brain images with sufficient accuracy for most clinical applications.
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| 3. |
- Bergström, Mats, et al.
(author)
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In vitro and animal validation of bromine-76-bromodeoxyuridine as a proliferation marker
- 1998
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 39:7, s. 1273-9
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Journal article (peer-reviewed)abstract
- The potential of 76Br-bromodeoxyuridine as a PET tracer for characterizing proliferation potential was investigated in multicellular tumor aggregates and in healthy rats and pigs. METHODS: Bromine-76-bromide was produced by proton irradiation of a 76Se-enriched target using a 17-MeV cyclotron and recovered by thermal diffusion. Bromine-76-BrdU was prepared from the corresponding trimethylstannate by an oxidative bromination. Multicellular aggregates from a carcinoid cell line and two bladder cancer cell lines were co-incubated with 76Br-BrdU and 3H-thymidine and the uptake and DNA incorporation analyzed. About 0.5 MBq 76Br-BrdU were injected in the tail vein of unanaesthetised Sprague-Dawley rats. Two to 36 hr later they were decapitated and the radioactivity concentration and fraction of radioactivity incorporated into DNA determined in five different organs and the blood. Parallel studies were performed in animals pretreated with hydroxyurea. In separate experiments, rats were given an injection of 76Br-bromide and organ uptake was evaluated after 20 hr. PET studies were performed in two pigs and the uptake in different organs was investigated after injection of 76Br-BrdU. In these studies, diuresis was induced by furosemide and mannitol and radioactivity in blood and organs was followed during 10 hr. RESULTS: In the cell aggregates, 30%-90% of the radioactivity was extracted in the DNA fraction. A good correlation was found between 76Br-BrdU and 3H-thymidine with respect to total uptake and DNA fraction. The DNA fraction increased from 2-10 hr after incubation. With in vivo injection in the rat, relatively high uptake of radioactivity was found in all organs, unrelated to the degree of DNA synthesis. However, inhibition by hydroxyurea occurred only in the spleen and intestines, organs which also showed a high degree of incorporation of 76Br-BrdU into DNA. In the pig, the highest in vivo uptake was observed in the red bone marrow and the intestines. In these organs, 70%-80% of the radioactivity was recovered in the DNA fraction. The concentration of radioactivity in the heart, liver and kidney was 3-10 times lower, and here the DNA fraction accounted for 10%-20% of the radioactivity. The decay-corrected radioactivity in blood and nonproliferating organs decreased with diuresis with a half-life of 13 and 16 hr, respectively. CONCLUSION: It is suggested that the radioactivity uptake as seen after the administration of 76Br-BrdU, is constituted by two parts: one relating to incorporation into DNA and one existing as free 76Br- or metabolites of 76Br-BrdU. If sufficient time has passed, 76Br- dominates other metabolites. A correct assessment of DNA-incorporated radioactivity using PET with 76Br-BrdU is not trivial and can only be made with due correction for 76Br-, using either a complementary investigation after hydroxyurea pretreatment (in animal studies) or a separate 76Br-bromide investigation. Alternatively, the free bromide can be eliminated partially through forced diuresis.
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| 4. |
- 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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| 5. |
- Lövqvist, Anna, et al.
(author)
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Comparative PET imaging of experimental tumors with bromine-76-labeled antibodies, fluorine-18-fluorodeoxyglucose and carbon-11-methionine
- 1997
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 38:7, s. 1029-1035
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Journal article (peer-reviewed)abstract
- The potential of a 76Br-labeled anti-carcinoembryonic antigen monoclonal antibody (MAb), 38S1, as tumor-imaging agent for PET was investigated in a comparative experimental study with [18F]fluorodeoxyglucose ([18F]FDG) and L-[methyl-11C]methionine ([11C]Met). METHODS: The three radiotracers were administered to nude rats carrying subcutaneous xenografts or liver metastases from a human colonic carcinoma. Tracer biodistribution was evaluated by PET imaging and radioactivity measurement of dissected tissues and also by whole-body autoradiography for subcutaneous xenografts. RESULTS: For PET imaging of subcutaneous tumors, 76Br-38S1 proved superior to the other radiotracers. Tumor-to-tissue ratios were, except for the tumor-to-blood ratio, generally higher for 76Br-labeled MAb than for [18F]FDG and [11C]Met. Liver metastases were imaged with PET using both 76Br-38S1 and [18F]FDG, and the metastases-to-liver ratios of dissected samples were not significantly different for the two radiotracers. CONCLUSION: The tumor-imaging capacity of 76Br-labeled MAb 38S1 was superior to [18F]FDG and [11C]Met in the subcutaneous tumor model, whereas 76Br-38S1 and [18F]FDG were equally successful for the identification of liver metastases.
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| 6. |
- Lövqvist, Anna, et al.
(author)
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Pharmacokinetics and experimental PET imaging of a bromine-76-labeled monoclonal anti-CEA antibody
- 1997
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 38:3, s. 395-401
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Journal article (peer-reviewed)abstract
- Bromine-76 is potentially useful as a radiolabel for monoclonal antibodies (MAbs) in PET imaging. The purpose of the present study was to evaluate the 76Br-labeled anticarcinoembryonic antigen (-CEA) MAb 38S1 as a tumor imaging agent in an experimental tumor model and to study the pharmacokinetics of 76Br-38S1 in comparison with 125I-38S1. METHODS: Nude rats carrying human colon carcinoma xenografts were co-injected with directly labeled 76Br-38S1 and 125I-38S1. Biodistribution of labeled 38S1 was monitored for 4 days after administration, in the case of 76Br activity, including PET imaging. In addition, catabolism of radiolabeled MAbs was analyzed by gel filtration chromatography of blood plasma and homogenized tissues. RESULTS: Tumor sites could be readily identified by PET imaging from 46 hr after administration of 76Br-38S1 and onwards. The concentration of 76Br activity in tumors, blood and most normal tissues was higher than the corresponding 125I concentration at all time points. This was mainly due to catabolism of radiolabeled MAb, resulting in free radiohalides, of which 76Br- was retained in contrast to the rapidly excreted 125I- ion. CONCLUSION: Bromine-76-labeled anti-CEA MAbs may be applied for experimental tumor imaging with PET.
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| 7. |
- Mårtensson, Johan, et al.
(author)
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Chromium-51-EDTA clearance in adults with a single-plasma sample
- 1998
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 39:12, s. 2131-2137
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Journal article (peer-reviewed)abstract
- In 1996, a committee on renal clearance recommended a mean sojourn time-based methodology for single-sample determination of plasma clearance of 99mTc-diethylenetriamine pentaacetic acid (DTPA) to be used on adults if the patient's glomerular filtration rate (GFR) is suspected to be >30 ml/min. The main purpose of this study was to derive a mean sojourn time-based formula for calculation of 51Cr-ethylenediamine tetraacetic acid (EDTA) clearance in adults. Methods: Two groups of patients with 51Cr-EDTA clearance (CI) between 16 and 172 ml/min were studied. In Group I (n = 46), reference CI was determined as a multi plasma sample, single-injection method (CISM). Sixteen blood samples were drawn from 0 until 5 hr after a single intravenous injection of 51Cr-EDTA. In Group II (n = 1046), reference CI was determined by the Brøchner-Mortensen four-sample clearance method (CIBM). The plasma timeactivity curves of Group I were used to derive two mean sojourn time-based formulas (Formulas 1 and 2) for calculation of a single sample clearance. Formula 1 was derived from the entire time activity curve, whereas the derivation of Formula 2 used only the final slope of the time-activity curve. The accuracy of the two formulas and the Christensen and Groth 99mTc-DTPA formula was tested on Group II. Results: Chromium-51-EDTA CI calculated by Formula 1 was almost identical to the CI calculated by the reference CI method (r = 0.982; SDdiff = 5.82 ml/min). Both 51Cr-EDTA CI calculated by Formula 2 and by the 99mTc-DTPA formula showed close correlation with the reference method (r = 0.976, r = 0.985, respectively) but systematically overestimated GFR for the whole range of clearance values by 3.5 and 3.2 ml/min (p < 0.001), respectively. Conclusion: It is possible to get an accurate determi nation of 51Cr-EDTA CI from a single-plasma sample in adults by the mean sojourn time methodology. The determination is marginally more accurate (p < 0.001) if using a formula derived from the entire plasma time-activity curve than from only the final slope. The single-sample formula derived for determination of 99mTc-DTPA CI tends slightly to overestimate GFR if used to calculate 51Cr-EDTA CI.
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| 8. |
- Nettelbladt, Otto S, et al.
(author)
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Combined fluorine-18-FDG and carbon-11-methionine PET for diagnosis of tumors in lung and mediastinum
- 1998
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 39:4, s. 640-647
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Journal article (peer-reviewed)abstract
- We evaluated the value of PET using 18F-fluorodeoxyglucose (FDG) and 11C-methionine, individually or in combination, to distinguish malignant from benign tumors and to identify or exclude mediastinal metastases.METHODS:Seventeen patients with a tumor in the lung or mediastinum were evaluated with 18F-FDG and 11C-methionine PET. For morphological comparison, we used CT, and all findings were confirmed by histology of surgical resection specimens (n = 16) or by cytology (n = 1).RESULTS:All tumors were visualized equally well with both tracers, and there were no false-positive results. In 2 patients with a malignant tumor, coexisting pneumonia was correctly diagnosed as an inflammatory lesion because of its wedge-like shape. PET correctly excluded hilar invasion and mediastinal lymph node metastases in 10 of 14 patients with primary lung tumor. PET identified mediastinal metastases in 4 of 4 patients. CT failed to detect mediastinal tumor spread in 2 patients and gave a false-positive reading in 2 others. Significantly higher uptake (SUV) and transport rate (slope) values were obtained from malignant than benign lesions with both tracers. No major differences were seen in either the levels of significance or accuracy when the two tracers were compared. Slope values did not add further information to what was obtained with SUV. Density correction of SUV and slope values, to avoid the influence of surrounding air as well as tumor heterogeneity, increased these differences somewhat. Both tracers distinguished malignant from benign lesions with a 93% sensitivity and an accuracy of 89%-95%, but sensitivity improved to 100% when values from both tracers were combined.CONCLUSION:Fluorine-18-FDG and 11C-methionine PET visualized all tumors equally well and detected mediastinal spread better than CT. For differentiation purposes, the problems of false-positive and false-negative PET findings could not be safely overcome in a limited number of cases either by the use of both tracers, by the additional use of slope values or by lesion density correction.
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| 9. |
- Rodriguez, Miriam, et al.
(author)
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Predicting malignancy grade with PET in non-Hodgkin's lymphoma
- 1995
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 36:10, s. 1790-1796
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Journal article (peer-reviewed)abstract
- Our goal was to determine whether PET with 11C-methionine and/or 18FDG could predict malignancy grade in non-Hodgkin's lymphoma (NHL). METHODS: Twenty-three patients with high-grade, low-grade or transformed low-grade NHL were investigated. Standardized uptake values (SUV), transport rate and mass influx values were calculated both for the whole tumor [mean regions of interest, (ROI)] and for the tumor area with the highest levels of activity, comprising four contiguous pixels within each tumor and designated as a hot spot. RESULTS: Both 11C-methionine and 18FDG detected all tumors. In addition, 18FDG discriminated between high- and low-grade NHL, whereas 11C-methionine did not. With 18FDG, three transformed low-grade NHLs behaved in an intermediate manner. All quantitative uptake values correlated well with each other for both tracers, except for the mean ROI SUV and transport rate of 11C-methionine. Quantifications of mean ROI uptake and hot spots were strongly correlated. CONCLUSION: The results of this study together with previous findings from other studies indicate that 18FDG but not 11C-methionine can predict malignancy grade in NHL. Further studies with a larger series of patients are needed.
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| 10. |
- Sundin, Anders, et al.
(author)
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PET and parathyroid L-[carbon-11]methionine accumulation in hyperparathyroidism
- 1996
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In: Journal of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 37:11, s. 1766-1170
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Journal article (peer-reviewed)abstract
- The study was designed to characterize L-[methyl-11 C]methionine accumulation in abnormal parathyroid tissues of hyperparathyroidism (HPT).METHODS:Thirty-four patients with primary (n = 32) or secondary HPT were investigated with PET before primary or reoperative (n = 25) parathyroid surgery. Parathyroid 11C-methionine accumulation was analyzed for integrated uptake values in defined tissue volumes standardized for the injected dose and body weight (SUV), four contiguous pixels of maximal accumulation (SUVhs), SUV multiplied by area of region of interest (SUVr) and by the excised tissue weight (SUVw). Transport rate constants (slope, slopehs) were calculated according to Patlak's formula using plasma 11C activity corrected for 11C-methionine metabolites.RESULTS:True-positive localization was achieved in 85% of patients in whom 81% of the excised parathyroid lesions were visualized; no false-positive results were obtained. Corresponding proportions were 59% and 57% for CT and 55% and 52% for ultrasound, respectively. In the true-positive cases, parathyroid SUV, SUVhs and transport rate constants were consistently higher (p < 0.01) than in the thyroid, pharynx-esophagus, neck muscle and apical lung. Parathyroid SUV, SUVhs and SUVr increased with intact serum parathyroid hormone and calcium values (p = 0.0001-0.031), and weight of the excised tissue correlated with SUV and SUVhs (p = 0.024, 0.044). Parathyroid SUVhs varied strongly with the transport rate constants (p = 0.0008), and SUVr as well as s-calcium values differed significantly between parathyroid adenomas (n = 11), chief cell hyperplasias (n = 13), inadvertent implants (n = 3) and parathyroid cancers (n = 3).CONCLUSION:Carbon-11-methionine PET has potential application in preoperative localization and metabolic characterization of abnormal parathyroid tissues in human HPT.
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