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M Teräs

Publications and source records attributed to M Teräs.

At least 37 records · Page 2Linked to original sources
PubMed1995

Carbon-11-methionine PET imaging of malignant melanoma.

UNLABELLED: The purpose of the study was to assess the feasibility of PET and L-[methyl-11C]methionine (11C-methionine) in the detection of malignant melanoma. METHODS: Ten patients diagnosed with malignant melanoma (two with primary melanoma and eight with metastatic melanoma of the skin) but had no liver metastases underwent a PET study before starting cancer therapy. Dynamic scanning was performed for 40 min in seven patients and 10-20 min in three patients 25-45 min postinjection. RESULTS: Carbon-11-methionine PET detected all melanoma lesions greater than 1.5 cm (n = 22) in diameter, whereas five smaller pulmonary lesions were not detected. The average standardized uptake value of the untreated lesions was 6.3 +/- 2.1 (n = 19) and the uptake rate (influx constant) was 0.085 +/- 0.041 min-1 (n = 16). CONCLUSION: PET imaging with 11C-methionine is an effective method for visualizing melanoma. It may also be useful in measuring tumor metabolic activity in vivo.

Adult↗
PubMed1995

FDG-PET in early infancy: simplified quantification methods to measure cerebral glucose utilization.

UNLABELLED: For further insight into the physiology and pathogenesis of the developing brain, quantification of the cerebral glucose metabolism is needed. Arterial blood sampling or sampling of great volumes of blood is not justified for the purpose of PET studies in children. Therefore, we have developed simplified PET approaches to analyze brain FDG examinations during infancy. METHODS: The study consisted of 18 FDG-PET examinations chosen from our research protocols concerning hypoxicischemic encephalopathy and severe neonatal hypoglycemia. The input function for graphical analysis according to Patlak was derived in two ways: (1) a combined time-activity curve derived from the left ventricular activity concentration (first 7-17 min of the study) and radioactivity concentration in venous whole-blood samples and; (2) activity concentration measured in whole-blood venous blood samples (arterial plasma in one case). As an alternative for semiquantitation, the standardized uptake values (SUV) were calculated and correlated to local cerebral metabolic rates for glucose (LCMRGlc). RESULTS: The influx rate constants (Ki) and LCMRGlc values obtained using the combined curve versus venous curve did not differ statistically (p > 0.05). There was a good correlation between the SUV and LCMRGlc values (r = 0.83, p < 0.001). CONCLUSION: Local cerebral metabolic rates for glucose can be accurately calculated by using the combined curve (left ventricular activity concentration during first 5 min of the study and 2-3 venous whole-blood samples at the end of the study) for even the smallest pediatric patients. When blood samples cannot be obtained, SUV values provide an alternative for estimation of the cerebral glucose uptake and interindividual comparison of the patients.

Brain↗
PubMed1995

Metabolic imaging of ovarian tumors with carbon-11-methionine: a PET study.

UNLABELLED: This study examines the potential of 11C-methionine as a PET tracer in metabolic imaging of benign and malignant ovarian tumors. METHODS: Four patients with one or two benign ovarian tumors (endometriomas or cystadenomas), two patients with a tumor of borderline malignancy and seven patients with ovarian cancer were studied with 11C-methionine and PET before laparotomy. CT or MRI were performed as a reference. Tracer uptake was quantitated by calculating tracer standardized uptake values (SUVs) and the kinetic influx constants (Ki values). RESULTS: Benign or borderline malignant tumors did not accumulate 11C-methionine, whereas all carcinomas had significant uptake. The mean SUV of the primary carcinomas was 7.0 (s.d., 2.2) and the mean Ki was 0.14 min-1 (s.d., 0.1 min-1), but the distribution of tracer uptake was highly heterogenous in four of six tumors. CONCLUSION: Ovarian cancer can be imaged with 11C-methionine and PET. This method also may be of value in the differential diagnosis between benign and malignant ovarian neoplasms. Due to physiological accumulations and methodological limitations, the value of 11C-methionine PET in the staging of ovarian cancer appears to be limited.

Adenocarcinoma, Clear Cell↗
PubMed1994

In vivo effects of insulin on tumor and skeletal muscle glucose metabolism in patients with lymphoma.

BACKGROUND: The anabolic properties of insulin have been suggested for use to reverse malnutrition associated with cancer. The host and tumor sensitivities to insulin are critical for such treatments, which aim to improve patient nutrition. The authors studied insulin effects on tumor and skeletal muscle metabolism with 2-[18F]-fluoro-2-deoxy-D-glucose ([18F]FDG) and positron emission tomography (PET). METHODS: Six patients with lymphoma twice underwent [18F]FDG-PET imaging: once after fasting overnight and once during euglycemic hyperinsulinemic clamp. The dynamic uptake of the glucose analogue [18F]FDG was measured in diseased nodes and upper arm skeletal muscle in both metabolic states. The [18F]FDG uptake in muscle and the whole body glucose use during euglycemic hyperinsulinemic clamp were compared with those of weight-matched healthy subjects studied under similar circumstances. RESULTS: In lymphomatous tissue, [18F]FDG uptake rates were similar in overnight fasting and euglycemic hyperinsulinemic clamp (38 +/- 10 versus 41 +/- 9 mumol/100 g/minute, not significant), whereas glucose uptake in skeletal muscle was increased by insulin (1.7 +/- 0.2 versus 3.8 +/- 0.5 mumol/100 g/minute, P = 0.012). Both basal (2.3 +/- 0.2 mumol/100 g/minute, P = 0.061) and insulin-stimulated (8.5 +/- 1.9 mumol/100 g/minute, P = 0.055) skeletal arm muscle glucose uptake rates were higher in control subjects than in patients. Whole body glucose use was 55% lower in patients than in control subjects (17 +/- 3 mumol/kg/minute versus 38 +/- 3 mumol/kg/minute, P = 0.002), consistent with insulin resistance in cancer. CONCLUSIONS: We found that insulin does not induce major changes in glucose uptake of lymphomatous tissue. Although insulin sensitivity of skeletal muscle was also reduced in patients with lymphoma, the net insulin effect may counteract imbalance between glucose uptake of tumor and muscle, offering a potential means to circumvent at least some metabolic abnormalities found in cancer.

Adult↗
PubMed1994

A hybrid method of attenuation correction for positron emission tomography brain studies.

A hybrid method for attenuation correction (HAC) in positron emission tomography (PET) brain studies is proposed. The technique requires the acquisition of two short (1 min) transmission scans immediately before or after the emission study, with the patient and the head fixation system in place and after removing the patient from the scanner with the head fixation system alone. The method combines a uniform map of attenuation coefficients for the patient's head with measured attenuation coefficients for the head fixation system to generate a hybrid attenuation map. The HAC method was calibrated on 30 PET cerebral studies for comparison with the conventional measured attenuation correction method by ROI analysis. Average differences of less than 3% were found for cortical and subcortical regions. The HAC technique is particularly suitable in a PET clinical environment, allowing a reduction of the total study time, greater comfort for patients and an increase in patient throughput.

Brain↗
PubMed1994

Head and neck cancer: effect of food ingestion on uptake of C-11 methionine.

PURPOSE: To determine the influence of a standardized meal on tumor uptake measured with positron emission tomography (PET) and L-(methyl-carbon-11) methionine. MATERIALS AND METHODS: Five patients with untreated squamous cell cancer of the head and neck underwent PET, first in a fasting state and then 6-7 days later after ingesting a liquid meal. RESULTS: All tumors were seen on PET scans, and image quality remained good after food ingestion. The standardized uptake values of the tumors were 3.7-11.4 in the fasting state but decreased after the meal (range, 3.3-10.0; P < .04). No substantial change was measured in tumor C-11 methionine influx constants (Ki values). CONCLUSION: Although cancer imaging with PET and C-11 methionine can be performed even in the patient has not fasted, a standardized meal may decrease tumor C-11 methionine uptake.

Aged↗
PubMed1994

Effect of antilipolysis on heart and skeletal muscle glucose uptake in overnight fasted humans.

We quantitated how lowering of free fatty acid (FFA) by an antilipolytic agent (acipimox) in the fasting state changes glucose uptake in heart and skeletal muscles. Glucose uptake in these tissues was measured two times in seven normal subjects, once after acipimox and once after placebo, using positron emission tomography-derived [18F]fluoro-2-deoxy-D-glucose kinetics. Plasma glucose and insulin remained at their fasting concentrations in both studies. Fasting FFA concentrations were 60% lower after acipimox (238 +/- 39) than placebo (645 +/- 78 mumol/l, P < 0.001). Glucose uptake increased 6 +/- 2-fold in the heart by acipimox (344 +/- 49 vs. 108 +/- 40 mumol.kg muscle-1.min-1, P < 0.002) and 1.5-fold in arm muscles (27.7 +/- 2.6 vs. 18.6 +/- 1.2 mumol.kg muscle-1.min-1, P < 0.02). Heart (r = -0.93, P < 0.001) and arm (r = -0.82, P < 0.001) glucose uptakes were inversely related to serum FFA. We conclude that serum FFA are inversely related to glucose uptake in heart and arm skeletal muscles after an overnight fast. These data indicate that compensatory glycogenolysis, although it may occur, does not prevent operation of the glucose-FFA cycle under fasting conditions.

Adult↗
PubMed1994

Different alterations in the insulin-stimulated glucose uptake in the athlete's heart and skeletal muscle.

Physical training increases skeletal muscle insulin sensitivity. Since training also causes functional and structural changes in the myocardium, we compared glucose uptake rates in the heart and skeletal muscles of trained and untrained individuals. Seven male endurance athletes (VO2max 72 +/- 2 ml/kg/min) and seven sedentary subjects matched for characteristics other than VO2max (43 +/- 2 ml/kg/min) were studied. Whole body glucose uptake was determined with a 2-h euglycemic hyperinsulinemic clamp, and regional glucose uptake in femoral and arm muscles, and myocardium using 18F-fluoro-2-deoxy-D-glucose and positron emission tomography. Glucose uptake in the athletes was increased by 68% in whole body (P < 0.0001), by 99% in the femoral muscles (P < 0.01), and by 62% in arm muscles (P = 0.06), but it was decreased by 33% in the heart muscle (P < 0.05) as compared with the sedentary subjects. The total glucose uptake rate in the heart was similar in the athletes and control subjects. Left ventricular mass in the athletes was 79% greater (P < 0.001) and the meridional wall stress smaller (P < 0.001) as estimated by echocardiography. VO2max correlated directly with left ventricular mass (r = 0.87, P < 0.001) and inversely with left ventricular wall stress (r = -0.86, P < 0.001). Myocardial glucose uptake correlated directly with the rate-pressure product (r = 0.75, P < 0.02) and inversely with left ventricular mass (r = -0.60, P < 0.05) or with the whole body glucose disposal (r = -0.68, P < 0.01). Thus, in athletes, (a) insulin-stimulated glucose uptake is enhanced in the whole body and skeletal muscles, (b) whereas myocardial glucose uptake per muscle mass is reduced possibly due to decreased wall stress and energy requirements or the use of alternative fuels, or both.

Adult↗
PubMed1994

Imaging of uterine carcinoma by carbon-11-methionine and PET.

UNLABELLED: L-[methyl-11C]methionine ([11C]methionine) is probably one of the most useful positron-emitting tracers for metabolic imaging of human cancer. In this study, we investigated whether human uterine cancer can be imaged with [11C]methionine and PET. METHODS: Fourteen patients with primary uterine malignancy participated in the study. Eight patients had endometrial carcinoma and six had cervical carcinoma. The normal endometrium was analyzed in four additional patients with no uterine malignancy and in one patient with cervical cancer. Tracer uptake was quantitated by calculating both the standardized uptake values (SUVs) and the kinetic influx constants (Ki values) for the tracer. RESULTS: All patients with either cervical or endometrial carcinoma had increased uptake of [11C]methionine in the PET image. The mean SUV of the carcinomas was 8.4 (n = 13; s.d., 1.5) and the mean Ki was 0.15 min-1 (n = 12; s.d., 0.08 min-1), whereas the mean SUV of the normal endometrium was only 4.6 (n = 5; s.d., 0.8). Histologically poorly (Grade III) or moderately (Grade II) differentiated endometrial carcinomas accumulated more [11C]methionine than the well-differentiated (Grade I) ones (p = 0.04 for the SUVs, and p = 0.05 for the Ki values). There were also variable physiological accumulations of [11C]methionine in the pelvis. CONCLUSIONS: Uterine carcinoma accumulated [11C]methionine more than the normal endometrium. However, the physiological accumulations of [11C]methionine in the pelvis may confuse the interpreter of the PET image; thus, morphological imaging also needs to be performed as a reference to localize the tumor accurately. We conclude that human uterine carcinoma can be effectively imaged with [11C]methionine and PET.

Adenocarcinoma↗
PubMed1994

Enhancement of myocardial [fluorine-18]fluorodeoxyglucose uptake by a nicotinic acid derivative.

UNLABELLED: Recently, the euglycemic hyperinsulinemic clamp technique was shown to give excellent image quality during metabolic steady-state conditions. Acipimox is a new potent nicotinic acid derivative that rapidly reduces serum free fatty acid (FFA) levels by inhibiting lipolysis in peripheral tissue. METHODS: To compare the effects of acipimox administration and insulin clamp on [18F]fluorodeoxyglucose ([18F]FDG) uptake and myocardial glucose utilization, five nondiabetic and seven type II diabetic patients who had had previous myocardial infarctions were studied twice: once during a clamp study and once after the administration of acipimox (2 x 250 mg orally). All patients also underwent resting SPECT perfusion imaging prior to PET scans. RESULTS: The patients tolerated acipimox well. Although fasting plasma glucose levels were higher in diabetic patients (9.2 +/- 3.4 versus 5.5 +/- 0.3 mM, p = 0.03), they were decreased both during clamping and after acipimox; during imaging, no significant differences between the groups and approaches were detected. By visual analysis, the image quality and myocardial [18F]FDG uptake patterns were similar during clamping and after acipimox. Compared with the relative [18F]FDG uptake values obtained during clamping, acipimox yielded similar results in normal, mismatch and scar segments (r = 0.88, p = 0.0001). Similar rMGU values were also obtained during both approaches. CONCLUSION: Thus, PET imaging with [18F]FDG after the administration of acipimox is a simple and feasible method for clinical viability studies both in nondiabetic and diabetic patients. It results in excellent image quality and gives rMGU levels similar to the insulin clamp technique.

Adult↗
PubMed1993

Carbon-11-methionine and PET in evaluation of treatment response of breast cancer.

Uptake of L-methyl-11C-methionine (11C-methionine) in breast cancer metastases was studied with positron emission tomography (PET). Eight patients with soft tissue metastases were studied twice: before the onset of chemotherapy (4), hormonal therapy (3) or radiotherapy (1) and 3-14 weeks later. The radioactivity concentration of the low molecular weight fraction of venous plasma samples separated by fast gel filtration was used as input function. The input corrected uptake rate of 11C-methionine (Ki) in breast cancer metastases before the treatment ranged between 0.035 and 0.186 1 min-1 and the standardised uptake value (SUV) between 2.0 and 11.4. The uptake of 11C-methionine into the metastases decreased when clinical objective stability or regression of the metastases was later obtained and increased in cases where progressive disease was seen during treatment. We conclude that metabolic changes in the amino acid metabolism detected by PET precede the clinical response, and may be of clinical value in predicting the treatment response.

Aged↗
PubMed1993

Insulin resistance is localized to skeletal but not heart muscle in type 1 diabetes.

To determine the tissue localization of insulin resistance in type 1 diabetic patients, whole body and regional glucose uptake rates were determined under euglycemic hyperinsulinemic conditions. Leg, arm, and heart glucose uptake rates were measured using positron emission tomography-derived 2-deoxy-2-[18F]-fluoro-D-glucose kinetics and the three-compartment model described by Sokoloff et al. (L. Sokoloff, M. Reivich, C. Kennedy, M.C. DesRosiers, C.S. Patlak, K.D. Pettigrew, O. Sakurada, and M. Shinohara. J. Neurochem. 28: 897-916, 1977) in eight type 1 diabetic patients and eight matched normal subjects. Whole body glucose uptake was quantitated by the euglycemic insulin clamp technique. Whole body glucose uptake was approximately 31% lower in the diabetic patients (P < 0.01) than in the normal subjects, thus confirming the presence of whole body insulin resistance. The rate of glucose uptake was approximately 45% lower in leg muscle when measured in the femoral region (55 +/- 7 vs. 102 +/- 13 mumol.kg muscle-1.min-1, diabetic patients vs. normal subjects, P < 0.05) and approximately 27% lower in the arm muscles (66 +/- 4 vs. 90 +/- 13 mumol.kg muscle-1.min-1, respectively, P < 0.05), whereas no difference was observed in heart glucose uptake [789 +/- 80 vs. 763 +/- 58 mumol.kg muscle-1.min-1 not significant (NS)]. Whole body glucose uptake correlated with glucose uptake in femoral (r = 0.93, P < 0.005) and arm muscles (r = 0.66, P < 0.05) but not with glucose uptake in the heart (r = 0.04, NS). We conclude that insulin resistance in type 1 diabetic patients is localized to skeletal muscle, whereas heart glucose uptake is unaffected.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Radioimmunodetection of prostate cancer by 111In-labeled monoclonal antibody against prostatic acid phosphatase.

Purified human prostate acid phosphatase (PAP) was used to generate a specific monoclonal antibody (FC 3001) for detection of PAP expressed by some prostatic carcinomas. DTPA derivatives of MoAb-F(ab')2-fragments were labeled with indium-111 chloride. This labeled antibody was tested in 15 prostate cancer patients who underwent staging pelvic lymphadenectomy; 9 of them received labeled antibody alone whereas 6 received simultaneous injections of labeled and unlabeled antibody with two dose levels (40 or 80 mg). Biodistribution data obtained by direct blood measurements and imaging procedures indicated that simultaneous injection of unlabeled antibody reduced both the blood elimination rate and the accumulation in the liver. Accumulation of the radionuclide in pelvic lymph node metastases was observed in some patients but in a couple of patients accumulation was noted also in normal lymph nodes. The method cannot in its present design replace staging pelvic lymphadenectomy and further studies are needed for elaboration of clinically useful radioimmunodetection methods.

Acid Phosphatase↗
PubMed1993

Heart and skeletal muscle glucose disposal in type 2 diabetic patients as determined by positron emission tomography.

Myocardial and skeletal muscle glucose uptake was examined in 9 type 2 diabetic patients and 13 control subjects using PET and the insulin clamp technique. All subjects had clinically stable coronary heart disease. To simulate the clinical situation, diabetic patients were kept slightly hyperglycemic during the clamp study. Consequently, there were no differences in skeletal muscle or total body glucose disposal between the two groups. With PET, myocardial glucose uptake was 12-20-fold greater than that in skeletal muscle in both groups. However, in the diabetic patients, myocardial glucose uptake was 39% lower (p < 0.05) than in the control subjects. These data suggest a defect in myocardial glucose utilization in type 2 diabetes and emphasize the need for standardized metabolic conditions in diabetic patients during 18FDG PET imaging.

Coronary Disease↗
PubMed1993

The value of quantitative analysis of glucose utilization in detection of myocardial viability by PET.

To study whether absolute quantitation of regional myocardial glucose utilization (rMGU) enhances detection of myocardial viability, 70 nondiabetic patients with prior myocardial infarction and angiographically confirmed coronary artery disease were studied with [18F]FDG PET after oral glucose loading. Forty-eight patients were also revascularized and underwent echocardiography after revascularization to detect wall motion recovery. The rMGU was calculated in eight myocardial segments in each patient and the results were compared to normalized (relative) [18F]FDG uptake values. In normal segments (n = 225), rMGU was 56 +/- 18 mumole/min/100 g (mean +/- s.d.) and relative [18F]FDG uptake 97% +/- 12%. The interindividual variation of rMGU in normal myocardium was greater than the intraindividual variation (s.d. 31% versus 11%). The respective values for relative [18F]FDG uptake were 9% and 10%. Both rMGU and [18F]FDG uptake were significantly reduced in segments with scarring observed visually during bypass surgery (29 +/- 19 mumole/min/100 g and 45% +/- 22%, n = 26). The rMGU and [18F]FDG uptake were higher in segments that recovered after revascularization (53 +/- 17 mumole/min/100/g and 110% +/- 21%, n = 27) than in those that did not (37 +/- 20 mumole/min/100 g and 65% +/- 24%, n = 63). However, due to larger variability of rMGU values, normalized [18F]FDG uptake was superior to rMGU in separating normal and scar segments as well as in predicting wall motion recovery. We conclude that rMGU variability is notable and is caused mainly by variations between patients. Interindividual variation is reduced by normalization, which results in more accurate assessment of myocardial viability. Thus, static imaging and semiquantitative analysis are sufficient for the clinical assessment of myocardial viability.

Coronary Angiography↗
PubMed1993

Comparison of fluorine-18-fluorodeoxyglucose and carbon-11-methionine in head and neck cancer.

The positron emission tomography (PET) tracer 2-18F-fluoro-2-deoxy-D-glucose (FDG) is the most widely used tracer in oncology. PET tracer. Another radiotracer, L-methyl-11C-Methionine (11C-methionine), also has been used successfully for PET imaging of brain and lung tumors, non-Hodgkin's lymphoma, breast cancer and head and neck cancer. This study compared FDG and 11C-methionine as tumor-detecting agents in head and neck cancer. Prior to cancer therapy, fourteen patients underwent a PET study with FDG and one with 11C-methionine. Nineteen of 21 malignant lesions that could be evaluated were visible with both tracers. Tracer uptake was measured as standardized uptake values (SUV) and Ki values according to Patlak et al. The mean SUV in FDG studies was 7.7 +/- 4.2 and in 11C-methionine studies 7.7 +/- 2.5, whereas the Ki values in 11C-methionine studies (mean, 0.128 +/- 0.068 min-1) were always higher than in FDG studies (mean, 0.036 +/- 0.023 min-1). A good correlation was found between the SUVs (r = 0.79, p < 0.0001) and the Ki values (r = 0.82, p < 0.001) between the two tracers. Both FDG and 11C-methionine are effective in PET imaging of head and neck cancer, and the uptake rates of the tracers seem to be closely related.

Adult↗
PubMed1992

Glucose-free fatty acid cycle operates in human heart and skeletal muscle in vivo.

Positron emission tomography permits noninvasive measurement of regional glucose uptake in vivo in humans. We employed this technique to determine the effect of FFA on glucose uptake in leg, arm, and heart muscles. Six normal men were studied twice under euglycemic hyperinsulinemic (serum insulin approximately 500 pmol/liter) conditions, once during elevation of serum FFA by infusions of heparin and Intralipid (serum FFA 2.0 +/- 0.4 mmol/liter), and once during infusion of saline (serum FFA 0.1 +/- 0.01 mmol/liter). Regional glucose uptake rates were measured using positron emission tomography-derived 18F-fluoro-2-deoxy-D-glucose kinetics and the three-compartment model described by Sokoloff (Sokoloff, L., M. Reivich, C. Kennedy, M. C. Des Rosiers, C. S. Patlak, K. D. Pettigrew, O. Sakurada, and M. Shinohara. 1977. J. Neurochem. 28: 897-916). Elevation of plasma FFA decreased whole body glucose uptake by 31 +/- 2% (1,960 +/- 130 vs. 2,860 +/- 250 mumol/min, P less than 0.01, FFA vs. saline study). This decrease was due to inhibition of glucose uptake in the heart by 30 +/- 8% (150 +/- 33 vs. 200 +/- 28 mumol/min, P less than 0.02), and in skeletal muscles; both when measured in femoral (1,594 +/- 261 vs. 2,272 +/- 328 mumol/min, 25 +/- 13%) and arm muscles (1,617 +/- 411 to 2,305 +/- 517 mumol/min, P less than 0.02, 31 +/- 6%). Whole body glucose uptake correlated with glucose uptake in femoral (r = 0.75, P less than 0.005), and arm muscles (r = 0.69, P less than 0.05) but not with glucose uptake in the heart (r = 0.04, NS). These data demonstrate that the glucose-FFA cycle operates in vivo in both heart and skeletal muscles in humans.

Adult↗