Bernhard M. Dohmen

2-18fluoro-deoxy-D-glucose Positron Emission Tomography Is a Reliable Predictor for Viable Tumor in Postchemotherapy Seminoma: An Update of the Prospective Multicentric SEMPET Trial

PURPOSE To define the clinical value of 2-18fluoro-deoxy-D-glucose positron emission tomography (FDG PET) as a predictor for viable residual tumor in postchemotherapy seminoma residuals in a prospective multicentric trial. PATIENTS AND METHODS FDG PET studies in patients with metastatic pure seminoma who had radiographically defined postchemotherapy residual masses were correlated with either the histology of the resected lesion or the clinical outcome documented by computer tomography (CT), tumor markers, and/or physical examination during follow-up. The size of the residual lesions on CT, either >3 cm or < or =3 cm, was correlated with the presence or absence of viable residual tumor. RESULTS Fifty-six FDG PET scans of 51 patients were assessable. All 19 cases with residual lesions >3 cm and 35 (95%) of 37 with residual lesions < or =3 cm were correctly predicted by FDG PET. The specificity, sensitivity, positive predictive value, and negative predictive value of FDG PET were 100% (95% CI, 92% to 100%), 80% (95% CI, 44% to 95%), 100%, and 96%, respectively, versus 74% (95% CI, 58% to 85%), 70% (95% CI, 34% to 90%), 37%, and 92%, respectively, for CT discrimination of the residual tumor by size (>3 cm/< or =3 cm). CONCLUSION This investigation confirms that FDG PET is the best predictor of viable residual tumor in postchemotherapy seminoma residuals and should be used as a standard tool for clinical decision making in this patient group.

Fluorine-18 fluorodeoxyglucose positron emission tomography in the differential diagnosis of pancreatic carcinoma: a report of 106 cases

The aim of this study was to evaluate fluorine-18 fluorodeoxyglucose positron emission tomography ([18F]FDG PET) as a tool for the differential diagnosis of pancreatic carcinoma while taking into account serum glucose level. A group of 106 patients with unclear pancreatic masses were recruited for the study. PET was performed following intravenous administration of an average of 190 MBq [18F]FDG. Focally increased glucose utilisation was used as the criterion of malignancy. In addition, the \ldstandardised uptake value\rd (SUV) was determined 45 min after injection. Carcinoma of the pancreas was demonstrated histologically in 74 cases, and chronic pancreatitis in 32 cases. Employing visual evaluation, 63 of the 74 (85%) pancreatic carcinomas were identified by PET. In 27 of the 32 cases (84%) of chronic pancreatitis il was possible to exclude malignancy. False-negative results (n=11) were obtained mostly in patients with raised serum glucose levels (10 out of 11), and false-positives (n=5) in patients with inflammatory processes of the pancreas. Thus PET showed an overall sensitivity of 85%, a specificity of 84%, a negative predictive value of 71%, and a positive predictive value of 93%. In a subgroup of patients with normal serum glucose levels (n=72), the results were 98%, 84%, 96% and 93%, respectively. Quantitative assessment yielded a mean SUV of 6.4\+-3.6 for pancreatic carcinoma as against a value of 3.6\+-1.7 for chronic pancreatitis (P\s<0.001), without increasing the diagnostic accuracy. This shows PET to be of value in assessing unclear pancreatic masses. The diagnostic accuracy of PET examinations is very dependent on serum glucose levels.

Correlation of Stable Elevations in Striatal μ-Opioid Receptor Availability in Detoxified Alcoholic Patients With Alcohol Craving: A Positron Emission Tomography Study Using Carbon 11–Labeled Carfentanil

Main Outcome Measures: After 1 to 3 weeks of abstinence, the availability of μ-opiate receptors in the ventral striatum, including the nucleus accumbens, was significantly elevated in alcoholic patients compared with healthy controls and remained elevated when 12 alcoholic patients had these levels measured 5 weeks later (P .05 corrected for multiple testing). Higher availability of μ-opiate receptors in this brain area correlated significantly with the intensity of alcohol craving as assessed by the OCDS.

PET with [18F]fluorothymidine for imaging of primary breast cancer: a pilot study

The aim of this study was to evaluate the use of [18F]fluorothymidine (FLT) as a positron emission tomography (PET) tracer for the diagnosis of breast cancer. To this end, 12 patients with 14 primary breast cancer lesions (T2–T4) were studied by FLT-PET. For comparison, [18F]fluorodeoxyglucose (FDG) PET scans were performed in six patients. Thirteen of the 14 primary tumours demonstrated focally increased FLT uptake (SUVmean=3.4±1.1). Seven out of eight patients with histologically proven axillary lymph node metastases showed focally increased FLT uptake in the corresponding areas (SUVmean=2.4±1.2). The lowest SUV (mean =0.7) was observed in one of two inflammatory cancers. The contrast between primary tumours or metastases and surrounding tissue was high in most cases. In direct comparison to FDG-PET, the SUVs of primary tumours (5/6) and axillary lymph node metastases (3/4) were lower in FLT-PET (SUVFLT: 3.2 vs SUVFDG: 4.7 in primary tumours and SUVFLT: 2.9 vs SUVFDG: 4.6 in lymph node metastases). Since FLT uptake in surrounding breast tissue was also lower, tumour contrast was comparable to that with FDG. It is of note that normal FLT uptake was very low in the mediastinum, resulting in a higher tumour-to-mediastinum ratio as compared to FDG (P=0.03). FLT-PET is suitable for the diagnosis of primary breast cancer and locoregional metastases. High image contrast may facilitate the detection of small foci, especially in the mediastinum.

Predictive Impact of 2-18Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography for Residual Postchemotherapy Masses in Patients With Bulky Seminoma

PURPOSE To establish the predictive potential of 2-18fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) for detecting viable tumor tissue in residual postchemotherapy masses of seminoma patients. PATIENTS AND METHODS In this prospective multicenter trial, results of FDG PET studies in seminoma patients with postchemotherapy masses > or = 1 cm were correlated with either the histology of the resected lesion or the clinical outcome on follow-up without resection. Negative PET scans of residual lesions that were devoid of viable tumor tissue on resection or disappeared, shrunk, or remained stable in size for at least 2 years were rated as true-negative (TN). Positive scans without histologic or clinical evidence of tumor tissue were classified as false-positive. In patients with histologically positive or progressive lesions, positive PET scans were defined as true-positive (TP) and negative scans, false-negative (FN). RESULTS Thirty-seven PET scans of 33 patients were assessable at a median follow-up time of 23 months (range, 2 to 46 months). Histologic data were available from nine patients who had undergone resection. Twenty-eight patients were followed-up clinically and radiologically. Twenty-eight scans were TN, eight were TP, and one was FN. All 14 residual lesions more than 3 cm and 22 (96%) of the 23 < or = 3 cm were correctly predicted by FDG PET. The specificity (100%; 95% confidence interval [CI], 87.7% to 100%), sensitivity (89%; 95% CI, 51.7% to 99.7%), positive predictive value (100%), and the negative predictive value (97%) of FDG PET were superior to data obtained by assessing residual tumor size (< or = or > 3 cm). CONCLUSION FDG PET is a clinically useful predictor of viable tumor in postchemotherapy residuals of pure seminoma, especially those greater than 3 cm.

FDG PET for staging of advanced non-small cell lung cancer prior to neoadjuvant radio-chemotherapy

Abstract. The aim of this study was to evaluate positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) for the staging of non-small cell lung cancer (NSCLC) before combined neoadjuvant, i.e. preoperative, radio-chemotherapy (RCT). From November 1998 until September 2001, 101 patients with NSCLC were investigated prospectively. The inclusion criterion was a histologically proven NSCLC of stage IIIA or B according to conventional staging including biopsy. The results of PET were compared with those obtained by mediastinoscopy, computed tomography (CT), bone scan and abdominal ultrasonography. Validation of discrepant findings was achieved by biopsy or repeated CT. PET proved to be highly accurate for the detection of lymph node metastases (sensitivity 96%, specificity 73%, positive predictive value 88%, negative predictive value 89%, accuracy 88%) as well as distant metastases (in 25/101 patients, all previously unknown). PET findings changed further treatment in 29/101 patients (29%). Twenty-five were excluded from RCT due to the presence of previously unknown distant metastases. One patient was free of metastases and therefore was operated on without pre-treatment. Two patients did not receive any further treatment because a malignant tumour could be excluded after PET. In the final patient PET demonstrated a tumour pattern not typical for NSCLC which could be attributed to a seminoma after repeated biopsy. FDG PET is the most accurate non-invasive diagnostic procedure for the staging of advanced NSCLC. Therefore use of FDG PET is highly recommended in order to select patients for neoadjuvant or other stage-dependent treatment modalities.

Early prediction of treatment response to high-dose salvage chemotherapy in patients with relapsed germ cell cancer using ( 18 F)FDG PET

To assess the ability of [18F]fluorodeoxyglucose positron emission tomography for the early prediction of response in patients with relapsed metastatic germ cell tumours undergoing salvage high-dose chemotherapy. The role of positron emission tomography was compared with established means of tumour response assessment such as CT scans/MRI and serum tumour marker changes. In addition, positron emission tomography was compared with a current prognostic score which differentiates three prognostic groups with failure-free survival rates ranging from 5–50%. [18F]fluorodeoxyglucose uptake of metastases from germ cell tumours as well as CT scans and serum tumour marker were acquired after 2–3 cycles of induction chemotherapy but before the start of high-dose chemotherapy and CT scans/serum tumour marker were compared with the baseline examinations in 23 patients with relapsed germ cell tumours. To evaluate the validity of early response prediction by positron emission tomography, radiological monitoring and serum tumour marker decline, histopathologic response after resection of residual masses and/or the clinical course over 6 months after the end of treatment (relapse vs freedom of progression) were used. Overall, 10 patients (43%) achieved a marker-negative partial remission, three (13%) a marker-positive partial remission, five (22%) a disease stabilization and five (22%) progressed during treatment. Nine patients (39%) remained progression-free over 6 months following treatment, whereas 14 (61%) progressed. The outcome of high-dose chemotherapy was correctly predicted by positron emission tomography/CT scan/serum tumour marker in 91/59/48%. Eight patients with a favourably predicted outcome by CT scans plus serum tumour marker but a positive positron emission tomography prior to high-dose chemotherapy, failed treatment. This results in the following sensitivities/specificities for the prediction of failure of high-dose chemotherapy: positron emission tomography 100/78%; radiological monitoring 43/78%; serum tumour marker 15/100%. The positive and negative predictive values of positron emission tomography were 88 and 100%, respectively. As compared with the prognostic score, positron emission tomography was correctly positive in all patients of the three risk groups who failed treatment. In addition, a negative positron emission tomography correctly predicted a favourable outcome in the good and intermediate group. [18F]fluorodeoxyglucose positron emission tomography imaging can be used to assess response to chemotherapy in patients with relapsed germ cell tumours early in the course of treatment and may help to identify patients most likely to achieve a favourable response to subsequent high-dose chemotherapy. In patients with response to induction chemotherapy according to CT scans or serum tumour marker evaluation, positron emission tomography seems to add information to detect patients with an overall unfavourable outcome. It may also be a valuable addition to the prognostic model particularly in the good and intermediate group for further selection of patients who will profit from high-dose chemotherapy.

Simplified, automated synthesis of 3'[18F]fluoro-3'-deoxy-thymidine ([18F]FLT) and simple method for metabolite analysis in plasma

Summary 3′[18F]Fluoro-3′-deoxy-thymidine ([18F]FLT) (III) has been discussed to be a promising tracer for assessing tumor proliferation. In order to perform clinical studies for evaluating [18F]FLT a simplified labeling procedure was developed using 2,3′-anhydrothymidine with benzoyl as a protecting group in the 5′-position (I). In DMSO the labeling yield was 46% at 160 °C in 10 min. Hydrolysis was efficiently performed with 0.25% NaOH at room temperature within 10 min. The labeling procedure was transferred to a remote controlled synthesis module allowing the production of [18F]FLT in high activities. The overall radiochemical yield was 18.1 ± 5.4% (n = 55) with absolute yields of 9.2 ± 2.6 GBq of [18F]FLT at EOS ready for injection (60 min after EOB; irradiation parameters: 35 μA, 60 min) and specific activities of 100–220 GBq/μmol. A convenient cartridge method for metabolite analysis was developed and validated versus HPLC showing that after 90 min 69.0 ± 7.0% of the radioactivity in plasma (less than 20% of initial radioactivity) was unchanged [18F]FLT (26 patients with various tumors).

3′-Deoxy-3′-[18F]fluorothymidine (FLT) uptake in breast cancer cells as a measure of proliferation after doxorubicin and docetaxel treatment

INTRODUCTION The nucleoside analogue [(18)F]fluorothymidine (FLT) has been designed as a marker of cell proliferation that can be imaged in vivo by positron emission tomography. Clinical pilot studies have demonstrated decreasing FLT uptake following antiproliferative chemotherapy of breast cancer. However, the significance of posttreatment FLT uptake has not been evaluated at the cell level. The aim of this study was to investigate whether FLT uptake detects proliferation inhibition induced by docetaxel or doxorubicin treatment in an in vitro breast cancer model. METHODS Breast cancer cells (MCF-7) were treated with docetaxel or doxorubicin for 24 h at drug doses inducing 25-99% inhibition of clonogenic survival (IC(25) to IC(99)). Cellular FLT uptake was estimated at 4 h and at 1, 3 and 5 days interval from chemotherapy. [(3)H]Thymidine incorporation and S-phase fraction were measured for comparison. Analysis of variance and the Bland-Altman difference plot were employed for statistical analysis. RESULTS After treatment, FLT uptake was declined in dependence of the proliferation inhibition mediated by both chemotherapeutic agents (all P<.0001). The decrease of FLT was greater after doxorubicin treatment than after the corresponding docetaxel dose. With doxorubicin (IC(99)), FLT accumulation was reduced by 70% as early as 4 h after treatment. FLT uptake was closely correlated to [(3)H]thymidine incorporation and S-phase fraction (r=.84 to .93). CONCLUSIONS Right after docetaxel or doxorubicin treatment, FLT uptake corresponds to the reduction of tumor cell proliferation induced. [(18)F]FLT appears promising for monitoring chemosensitivity in breast cancer.

Rhenium-188 for inhibition of human aortic smooth muscle cell proliferation

PURPOSE To evaluate dose-dependent growth-modulating effects of the beta-gamma emitter Rhenium-188 on cultured human aortic smooth muscle cells (haSMC). METHODS AND MATERIALS HaSMC were plated in 25 cm(2) flasks. Two days after plating, cells were incubated with the Re-188 (beta E(max) 2.12 MeV, tissue range(max) < 10 mm, T(1/2) 17 h) for five days. The doses administered were 0.2 Gy, 1, 4, 6, 8, 16, and 32 Gy. After five days, the radionuclide was removed. Cell growth, cell cycle distribution, and clonogenic activity were analyzed for the following 25 days. RESULTS The 0.2 and 1 Gy groups did not show relevant growth-inhibiting effects compared to the control groups. The 4 to 32 Gy groups presented dose-dependent growth inhibition, with a complete growth arrest of the 16 and 32 Gy groups. Clonogenic activity of the smooth muscle cell was strongly inhibited from doses > or =8 Gy. Flow cytometry showed a lasting dose-dependent G2/M phase block. CONCLUSION Smooth muscle cell (SMC) growth can be controlled effectively with Re-188 for at least 25 days after radiation in vitro. As the first four weeks after arterial angioplasty are crucial concerning neointimal formation, Re-188 may be a valuable radionuclide to inhibit restenosis after arterial angioplasty.