Biomedical subjects

L G Strauss

Publications and source records attributed to L G Strauss.

At least 37 records · Page 2Linked to original sources

PubMed1995

Chemotherapeutic management of head and neck malignancies with positron emission tomography.

OBJECTIVE: Antineoplastic chemotherapy in cases of nonresectable advanced malignancies of the head and neck can be very debilitating for the patient. For individual treatment planning, it is important to evaluate the early clinical effect of therapy. Morphological parameters, such as the size of the tumor and its relationship to adjacent structures, which can be determined by a number of imaging procedures, hardly reflect early therapeutic effects. Therefore, the metabolic activity of the tumor should be studied during antineoplastic therapy. DESIGN: Positron emission tomography was performed in 12 patients with metastasizing squamous cell carcinomas of the oropharynx, hypopharynx, and larynx before and after the first chemotherapeutic cycle. RESULTS: The fludeoxyglucose F 18 uptake was increased in all tumors and lymph nodes. In most lesions, an obvious response to treatment was observed after the first cycle of chemotherapy. However, differences in metabolic activity and changes in metabolism occurred during therapy. The treatment response varied in different lymph nodes in the same patient. There was a linear relation between metabolic change and growth rate during therapy, with different regression functions for tumors and lymph node metastases. CONCLUSIONS: Positron emission tomography provides absolute and comparable quantitative data on tumor metabolism before and after chemotherapy. It is therefore a useful method for observation and possible improvement of therapeutic measures in patients undergoing systemic chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1995

Evaluation of tumour metabolism and multidrug resistance in patients with treated malignant lymphomas.

The management of patients with treated malignant lymphomas requires functional methods to differentiate a residual soft tissue mass. Patients with treated Hodgkin's lymphoma (HL, n = 20, 68 malignant lesions, three benign lesions) or non-Hodgkin's lymphoma (NHL, n = 26, 46 malignant lesions, one benign lesion) were studied with positron emission tomography (PET) and fluorine-18 deoxyglucose (FDG). Oxygen-15 labelled water was used (n = 14, 25 lesions) in addition to FDG in order to obtain information on the tissue perfusion. Long-term follow-up studies with PET and FDG were performed in nine patients up to 511 days after the initiation of second-line therapy. Fourteen patients underwent single-photon emission tomography (SPET) with technetium-99m sestamibi immediately prior to the first PET examination. PET with FDG displays a high sensitivity for the detection of viable tumour tissue, all the malignant lesions being correctly classified in this study. The possible limitations are inflammatory processes, which may obscure tumour detection due to increased FDG uptake, and malignant lesions with low FDG uptake due to reduced perfusion. Difficulties exist in the prognosis of long-term response, since the change in FDG uptake may be variable. Long-term therapy outcome was correlated with the slope values obtained from the standardized integral uptake (SIU) data, which provides a new approach for the evaluation of PET follow-up studies. 99mTc-sestamibi, which should reflect the multidrug resistance, was evaluated with respect to therapy outcome. A high uptake of 99mTc-sestamibi was observed in patients with stable disease or better. The data support the hypothesis that sestamibi may reflect multidrug resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1994

Metabolic and transcriptional changes in osteosarcoma cells treated with chemotherapeutic drugs.

Two cell lines derived from a lung metastasis of a rat osteosarcoma were treated with cisplatin (CDDP) and two phosphonic acid compounds (AMDP, DADP), AMDP-treated cells showed a decrease in FDG uptake, CDDP and DADP resulted in an increase. A block in G2 or in S and G2 phase was seen after CDDP and AMDP treatment. The changes in the cell cycle fractions were not related to the changes in FDG uptake. Furthermore, the transcription of the glucose transporter and hexokinase genes were elevated in CDDP and decreased in AMDP treated cells. However, the changes in FDG uptake were not fully explained by changes at the transcriptional level. The total uptake of thymidine was elevated although the incorporation of thymidine into DNA decreased. In both cell lines the changes in FDG uptake correlated with the changes in thymidine incorporation into DNA (r = 0.95 and r = 0.83, respectively). Cells with an increased FDG uptake showed a weaker growth inhibition than cells with a decrease in FDG uptake.

Animals↗

PubMed1994

[Differential diagnosis of neck swelling due to suspected metastasis using positron emission tomography].

A noninvasive diagnostic method for the evaluation of a suspicious mass in the neck can be of great value for further diagnostic approach. The differing metabolic activity of malignant and benign tumors offers the possibility to determine the status of a lesion by the quantitative evaluation of the glucose uptake by positron emission tomography (PET). The diagnostic relevance of the metabolic activity has been shown earlier in more than 50 malignant tumors of the head and neck (Reisser et al., HNO 40 [1992] 225-231). The present study demonstrates the determination of tumor status in two benign and two malignant tumors of the neck by PET. Quantitative evaluation of the glucose uptake revealed significantly higher values in malignant than in benign lesions. Therefore the determination of the glucose metabolism prior to the indispensable histological diagnosis of the status of a lesion can provide valuable hints for the further diagnostic and therapeutic approach to the lesion.

Aged↗

PubMed1993

[Clinical indications for PET in oncology].

Diagnostic success of PET in oncology is based on the frequently higher glucose metabolism of tumor tissue. This has been demonstrated for many tumor types in a sufficient number of patients. A clear indication for PET in oncology is the differentiation of residual tumor or tumor recurrence from fibrosis. PET furthermore permits to distinguish lymph node metastasis from other adenopathies irrespective of lymph node size. It is therefore of use in those situations where tumor stage is influencing therapeutic decisions i.e. when operability of a malignancy is in question. Studies on the validity of PET investigations have been conducted in colorectal, pulmonary, hepatic, musculoskeletal and urologic malignant lymphoma. Prior to chemo- or hormonotherapy the uptake of the chemotherapeutic agent (5-fluorouracil) or the presence of hormone receptors (estrogen receptors) can be measured. This permits to optimize therapies by minimizing adverse effects and to limit treatment by those promising success. The therapeutic success can be monitored and possible development of resistance of tumors or part of a tumor can be detected.

Breast Neoplasms↗

PubMed1993

48-hour rapid cycling: results of psychopathometric, polysomnographic, PET imaging and neuro-endocrine longitudinal investigations in a single case.

We report a 64-year-old patient suffering from rapid cycling bipolar disorder who was studied by means of polysomnography, neuroendocrine tests and PET (positron emission tomography) imaging. In a manner only partly compatible with the cholinergic-aminergic imbalance model of mania and depression, a linkage of REM sleep disinhibition and depressive mood was observed, but no decisive REM sleep delay was seen on manic days. Growth hormone secretion after clonidine stimulation was blunted on depressive and hypomanic days. A series of total sleep deprivations led to a positive effect on psychopathology for about two weeks. Carbamazepine treatment normalized REM sleep variables, damped the amplitude of mood cycling of the patient, increased TSH and decreased FT4.

Bipolar Disorder↗

PubMed1993

Perfusion of colorectal liver metastases and uptake of fluorouracil assessed by H2(15)O and [18F]uracil positron emission tomography (PET).

Perfusion and fluorouracil (FU) accumulation were assessed using positron emission tomography (PET) with H2(15)O and 18FU in 36 patients with colorectal liver metastases. The tracers were injected intravenously and via the hepatic artery. Standard uptake values (SUV) were calculated using a region of interest (ROI) technique. The perfusion of non-tumorous liver tissue was similar after intravenous (i.v.) and intra-arterial (i.a.) assessment [mean of 2.67 (s = 0.61) and 2.2 (s = 0.45)]. Metastases were found to be hypoperfused compared to normal liver tissue after i.v. examinations [mean 1.73 (s = 0.77)]; i.a. injections revealed greater perfusion in metastases [mean 6.41 (s = 5.47)]. Single metastases showed up to 10 times greater perfusion with the i.a. injection route than with the i.v. one. However, lesions with no change or lower perfusion were also observed. Generally, accumulation of 18FU in metastases after i.v. infusion was less than after i.a.. Correlation of i.v. perfusion and uptake was moderate (r = 0.54, P = 0.0001); i.a. correlation was only slightly better (r = 0.61, P = 0.008). Perfusion as measured by H2(15)O-PET does not generally predict uptake of 18FU in colorectal liver metastases. To measure FU uptake using PET and 18F seems to be the most accurate method. It would allow one to identify individual patients with considerably greater accumulation of 18FU following i.a. administration who should profit from a cross-over to intrahepatic chemotherapy.

Colorectal Neoplasms↗

PubMed1993

The relevance of positron emission tomography for the diagnosis and treatment of head and neck tumors.

A total of 48 patients with squamous cell carcinomas (SCC) of the head and neck were examined with positron emission tomography (PET) and 18Fluor-deoxyglucose (FDG). In 25 cases the FDG-PET-data were compared with flow cytometric data of the lesions to investigate the value of PET for the noninvasive determination of a tumor's proliferative activity. The quantitative analysis of the radioactivity concentrations revealed two groups of tumors with a different FDG-uptake. A correlation was seen between the proliferative index and the FDG-uptake with an r-value of 0.64 in the lower uptake group and an r-value of 0.81 in the higher uptake group. There was no correlation between any clinicopathological or morphological parameters of the tumors and the FDG-uptake. It is suggested that the different FDG uptake may correspond to differences at the molecular level. The PET-evaluation of therapeutic effects in patients with advanced SCC of the head and neck revealed different posttherapeutic changes of the metabolism in tumors and in lymph node metastases. Tumors were more sensitive to therapy than lymph node metastases. There was a high correlation between the growth rate and the change in FDG uptake with a different regression function for tumors and for lymph nodes. The data demonstrate the usefulness of PET and FDG for the evaluation of early therapeutic effects. Therefore PET can be applied for the treatment planning in patients with malignant tumors of the head and neck.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1993

Studies with positron emission tomography after systemic administration of fluorine-18-uracil in patients with liver metastases from colorectal carcinoma.

Fluorouracil (FU) is the most common cytostatic agent used for chemotherapy in patients with colorectal tumors. Fifty patients with 78 hepatic metastases from colorectal tumors were examined with positron emission tomography (PET) following intravenous infusion of 18F-FU. The uptake of the cytostatic agent was evaluated in normal liver parenchyma, liver metastases and the aorta. Tracer uptake was expressed with the standardized uptake value (SUV). The maximum liver activity was 11.3 SUV (mean value) with a standard deviation of 1.85 SUV. The highest activity concentrations were noted 30 min (mean value) postinjection. In comparison, the activity concentration of individual metastasis was low. Two hours after tracer injection, the mean activity in metastases was 1.3 SUV, but notable individual variation in uptake was seen. Fluorine-18 concentration values 2 hr after FU infusion were approximately 44% of the FU uptake 20 min postinfusion. Fifty-three metastases were also examined with 15O-labeled water. The examination was performed to compare the uptake of the nonmetabolized tracer with FU uptake. We noted a statistically significant correlation between 15O-water concentration, uptake of nonmetabolized FU 8 min after the end of the infusion and FU retention (120 min postinjection) in a subgroup of metastases. The results suggest that FU retention in different metastases is highly variable and mainly dependent on early FU uptake into tumor cells.

Colorectal Neoplasms↗

PubMed1993

Fluorodeoxyglucose imaging of advanced head and neck cancer after chemotherapy.

Positron emission tomography (PET) was applied to evaluate therapeutic effects in patients with advanced head and neck cancer for use in monitoring therapy. In 18 patients with histologically proven head and neck cancer, PET studies with 330-440 MBq 18F-fluorodeoxyglucose (FDG) were performed prior to the first chemotherapeutic cycle with cisplatin and 5-FU. A second examination after the first chemotherapeutic cycle was performed in 11 patients. Tumor or lymph node volumes were determined from CT slices and the growth rate was calculated assuming an exponential function. Uptake in a region of interest was used for the quantitative evaluation of the PET images after standardization to injected dose and body weight. FDG data were available for 6 tumors and 10 metastases, volumetric data for 5 tumors and 7 metastases. One lesion showed an increase, seven a decrease in FDG uptake and eight lesions remained unchanged. Multiple lymph nodes in the same patient showed different baseline metabolisms and also different changes following therapy. Tumors were more sensitive to therapy than lymph node metastases. The growth rate and the change in FDG uptake were highly correlated with different regression functions for tumors and lymph node metastases. These data demonstrate that PET with FDG can be used to assess early chemotherapeutic effects. The information gained with PET can be included for treatment planning in patients undergoing systemic chemotherapy.

Adult↗

PubMed1992

Assessment of an attenuation correction for SPET by means of PET images.

The attenuation correction for single photon emission computed tomography (SPET) data developed by Luig et al. was tested with positron emission tomography (PET) data. Since the PET attenuation correction is very precise, it may be used as a reliable measure of the functionality of the SPET correction. It was found that, in the case of homogeneous attenuation and activity distribution, the results of Luig's correction are equivalent to those obtained with the PET correction. Inhomogeneous distributions of activity are corrected satisfactorily as long as the absorption of the medium is sufficiently homogeneous. Inhomogeneous absorption, however, leads to inadequate correction. In the case of sections through the lung, Luig's method might 'correct' the data in the wrong direction.

Humans↗

PubMed1992

Metabolic design of combination therapy: use of enhanced fluorodeoxyglucose uptake caused by chemotherapy.

In order to quantify effects of an experimental chemotherapy, MCF7 cells were studied with 14C-fluorodeoxyglucose (FDG) and high-performance liquid chromatography (HPLC). Uptake measurements were performed 1 and 4 hr after the end of a therapy with hexadecylphosphocholine (HPC). A dose- and time-dependent increase of the FDG uptake after therapy was observed, with a maximum at 1 hr after therapy. These data were used to develop a new metabolic design of combination treatment. Several time-dose combinations of HPC and deoxyglucose (DOG) were analyzed for their effects on growth inhibition. The combinations using DOG in the period of pronounced enhancement of FDG uptake (1 hr after HPC treatment) were found to be the most effective with an improvement of up to 520% in growth inhibition. This metabolic design of combination treatment may also be applied in vivo, and PET can be used to optimize the time and dose schedule of the modified treatment protocol.

Antineoplastic Agents↗

PubMed1992

Therapy monitoring of presacral recurrences after high-dose irradiation: value of PET, CT, CEA and pain score.

21 patients were followed by positron-emission-tomography (PET) FDG (18Flourdeoxyglucose) uptake, physical examination, CT and CEA levels after combined photon-neutron irradiation for inoperable recurrent rectal carcinoma. In order to evaluate the response to radiotherapy symptomatic relief, CEA levels, decrease of tumor volume measured by CT analysis were correlated with the FDG-uptake. The objective of this study was also to investigate if the level of FDG-uptake prior to radiotherapy or the early decrease after therapy can be used as a prognostic factor. Prior to radiotherapy sacral pain was the predominant symptom. All malignancies showed measurable tumor masses, evaluation of CEA levels and enhanced tracer accumulation of FDG in the PET cross section. The mean FDG-uptake before radiotherapy was 2.3 +/- 1.1 (range 1.1 to 5.0) in 21 patients in contrast to 1.9 +/- 0.7 (range 0.8 bis 4.0) three months after radiotherapy. In six patients FDG concentration values decreased to the range of normal soft tissue, moreover, two of them relapsed after six and 22 months. Elevated FDG-uptake of the sacral bone was noted in PET cross sections in two patients, while there was no evidence of osseous alterations in CT. Normal levels of CEA were achieved in 14 patients and complete or partial pain relief in 20 of 21 patients. A decrease of tumor volume of more than 50% was detected in the follow-up CT scans of three patients but no complete remission was found. The result suggests that enhanced glucose uptake is associated with recurrent rectal cancer. However, enhanced glycolytic activity is related not only to malignant cells but also to all proliferating cells. To distinguish between proliferation, repair, inflammation, and residual viable tumor cells is not possible and may be responsible for an unchanged or elevated FDG-uptake after radiotherapy.

Adenocarcinoma↗

PubMed1992

[Evaluating the effectiveness of chemotherapy in patients with head-neck tumors using positron emission tomography (PET scan)].

Positron emission tomography (PET) demonstrates the qualitative and quantitative characteristics of multiple metabolic pathways. In a prospective study we evaluated the metabolism of glucose in the tumors of ten patients suffering from head and neck cancer before and after chemotherapy with cisplatin and 5-fluorouracil. Using 18-fluorodeoxyglucose (FDG), it was possible to show changes in tumor metabolism after chemotherapy. In general, chemotherapy reduced the volume of the primary tumor and the lymph nodes. There was a linear relation between the changes in metabolism and growth rate, but in a few patients the lymph nodes and the primary tumor showed a different metabolic reaction. With FDG metabolism and PET we were able to determine the response rate of the tumor in vivo before chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1992

[Diagnosis of energy metabolism in ENT tumors--a PET study].

The metabolism of malignant tumours can be determined in vivo by positron emission tomography. Fifty patients with malignant lesions of the head and neck were examined before therapy and followed up for 11-18 months. The course of the disease was related to the initial fluorodeoxyglucose (FDG) uptake of the tumour. There was a relation between FDG uptake and survival: an increased FDG uptake of more than 300-400% was related to a reduced survival rate. Patients with an uptake less than 300% had a much better prognosis.

Blood Glucose↗

PubMed1992

[Positron emission tomography (PET) in the evaluation of tumor proliferation and follow-up of therapy in ear, nose and throat tumors].

The uptake of 18F-Deoxyglucose (FDG) was studied in vivo in patients with head and neck tumors with positron emission tomography (PET) in relation to the proliferation rate of these tumors. The quantitative analysis of the radioactivity concentrations revealed two groups, showing a high or a lower FDG uptake pattern. In both groups the FDG uptake and the proliferation rate were correlated with a flat slope of the regression function. It is suggested that these differences in uptake in histologically identical tumor populations may correspond to differences at the molecular level, e.g. differences in the amount of the glucose carrier, perhaps caused by activated oncogenes. Furthermore PET was applied to evaluate therapeutic effects in patients with advanced head and neck cancer. We found that multiple lymph node metastases in the same patient can show a different baseline metabolism and also different changes following therapy. Tumors were more sensitive to therapy than lymph node metastases. The growth rate and the change in FDG uptake were highly correlated with different regression functions for tumors and lymph node metastases. These data demonstrate that PET with FDG can be used to assess early chemotherapeutic effects. The information gained with PET can be included in the treatment planning in patients undergoing systemic chemotherapy.

Carcinoma, Squamous Cell↗

PubMed1991

[What is the contribution of PET in tumor diagnosis today?].

Positron emission tomography (PET) permits qualitative and quantitative measurements of tumor metabolism in the patient. In the clinical setting, the present studies suggest that tumors with a potential for proliferation can be differentiated from scar tissue, soft tissue and benign lesions. Accumulation of tracer by lymph nodes identifies them as metastatic. On the basis of a quantification of the accumulation of tracer and its metabolites, information can be provided about the biological activity of a tumor, and presumably also about the prognosis. The response of a tumor to treatment can be monitored, in particular in combination with CT. Possible selection of resistant parts of the tumor can be determined, so that modification of treatment is possible. Modes of application can also be individualized by identifying pre-treatment advantages of intraarterial or systemic administration; recurrent tumors can be detected with a high degree of accuracy. However, to date, only limited numbers of cases are available, so that, in view of the very promising aspects of this modality, more widespread application followed by the evaluation of larger numbers of patients is needed.

Biomarkers, Tumor↗

PubMed1991

[PET scan in tumor diagnosis in the head and neck].

PET, a new method in nuclear medicine, allows the in vivo measurement of tumor metabolism and tumor perfusion. Absolute and standardized PET data can be used for comparative examinations before, during and after therapy. It thereby is possible to assess very early the efficacy of a therapy and also to change the therapeutic scheme. Furthermore PET studies with multiple parameters allow the evaluation of the biological behaviour of the tumor and yield information that is relevant for prognosis.

Energy Metabolism↗