Summary Aim: FDG PET in hyperglycaemic subjects often suffers from limited statistical image quality, which may hamper visual and quantitative evaluation. In our study the following insulin bolus protocol is proposed for acute correction of hyperglycaemia (> 7.0 mmol/l) in brain FDG PET. (i) Intravenous bolus injection of short-acting insulin, one I.E. for each 0.6 mmol/l blood glucose above 7.0. (ii) If 20 min after insulin administration plasma glucose is ≤ 7.0 mmol/l, proceed to (iii). If insulin has not taken sufficient effect step back to (i). Compute insulin dose with the updated blood glucose level. (iii) Wait further 20 min before injection of FDG. (iv) Continuous supervision of the patient during the whole scanning procedure. Methods: The potential of this protocol for improvement of image quality in brain FDG PET in hyperglycaemic subjects was evaluated by computer simulations within the Sokoloff model. A plausibility check of the prediction of the computer simulations on the magnitude of the effect that might be achieved by correction of hyperglycaemia was performed by retrospective evaluation of the relation between blood glucose level and brain FDG uptake in 89 subjects in whom FDG PET had been performed for diagnosis of Alzheimer's disease. Results: The computer simulations suggested that acute correction of hyperglycaemia according to the proposed bolus insulin protocol might increase the FDG uptake of the brain by up to 80%. The magnitude of this effect was confirmed by the patient data. Conclusion: The proposed management protocol for acute correction of hyper glycaemia with insulin has the potential to significantly improve the statistical quality of brain FDG PET images. This should be confirmed in a prospective study in patients.

Introduction: Imaging of the serotonergic innervation of the brain using positron emission tomography (PET) with the serotonin transporter (SERT) ligand [C-11] (+)McN5652 might be affected by serotonin in the synaptic cleft if there is relevant interaction between [C-11] (+)McN5652 and serotonin at the SERT. The aim of the present study therefore was to pharmacologically characterize the interaction of [C-11] (+)McN5652 and serotonin at the SERT.Methods: In vitro saturation analyses of [H-3]serotonin uptake into HEK293 cells stably expressing the human SERT were performed in the absence and presence of unlabelled (+)McN5652. Data were evaluated assuming Michaelis-Menten kinetics.Results: Unlabelled (+)McN5652 significantly reduced the maximal rate of serotonin transport V-max of SERT without affecting the Michaelis-Menten constant K-M.Conclusions: This finding indicates that (+)McN5652 inhibits scrotonin transport through the SERT in a noncompetitive manner. This might suggest that [C-11] (+)McN5652 PET is not significantly affected by endogenous serotonin. (c) 2006 Elsevier Inc. All rights reserved.

ABSTRACTBackground and Purpose. Statistical parametric mapping (SPM) gained increasing acceptance for the voxel‐based statistical evaluation of brain positron emission tomography (PET) with the glucose analog 2‐[18F]‐fluoro‐2‐deoxy‐d‐glucose (FDG) in patients with suspected Alzheimer's disease (AD). To increase the sensitivity for detection of local changes, individual differences of total brain FDG uptake are usually compensated for by proportional scaling. However, in cases of extensive hypometabolic areas, proportional scaling overestimates scaled uptake. This may cause significant underestimation of the extent of hypometabolic areas by the statistical test. Methods. To detect this problem, the authors tested for hyper metabolism. In patients with no visual evidence of true focal hypermetabolism, significant clusters of hypermetabolism in the presence of extended hypometabolism were interpreted as false‐positive findings, indicating relevant overestimation of scaled uptake. In this case, scaled uptake was reduced step by step until there were no more significant clusters of hypermetabolism. Results. In 22 consecutive patients with suspected AD, proportional scaling resulted in relevant overestimation of scaled uptake in 9 patients. Scaled uptake had to be reduced by 11.1%± 5.3% in these cases to eliminate the artifacts. Adjusted scaling resulted in extension of existing and appearance of new clusters of hypometabolism. Total volume of the additional voxels with significant hypometabolism depended linearly on the extent of the additional scaling and was 202 ± 118 mL on average. Conclusions. Adjusted scaling helps to identify characteristic metabolic patterns in patients with suspected AD. It is expected to increase specificity of FDGPET in this group of patients.

Neuronal cells are susceptible to cerebral ischaemia. As γ-aminobutyric acidA (GABAA) receptors are specific for neurones, functional receptor imaging using 123I-iomazenil (IMZ), a ligand to the GABA benzodiazepine receptor, has been proposed as an imaging modality for the assessment of neuronal integrity. However, there is only limited experience with IMZ in patients with acute cerebral infarction. Therefore, the aim of this study was to evaluate IMZ single photon emission computed tomography (SPECT) in patients with acute cerebral ischaemia. IMZ SPECT was performed in 21 patients with acute cerebral infarction 7-10 days after stroke onset. Eleven patients underwent systemic thrombolysis within 6 h after symptom onset (group 1), whereas 10 patients were treated conservatively (group 2). IMZ (150-200 MBq) was injected intravenously and imaging was performed using a dedicated four-head SPECT camera at 5 min (perfusion) and 90 min (receptor distribution) post-injection, with an acquisition time of 50 min each. Images were analysed by visual inspection. Four patients showed normal IMZ distribution, and 17 patients showed abnormalities of IMZ uptake on both early and late images. In six patients with regional uptake deficits, a crossed cerebellar diaschisis was observed on early images. Cerebellar inhomogeneity of tracer uptake was absent at the time of late images in all six patients. In eight patients, areas of hypoperfusion corresponded exactly to the regions of receptor deficiency (match). In five patients, preserved neuronal integrity was present in hypoperfused areas (mismatch). In four patients, normally or even hyperperfused areas exhibited regional receptor deficiency (inverse mismatch). In conclusion, IMZ SPECT demonstrated differences between regional perfusion and receptor distribution in about one-half of patients 7-10 days after acute cerebral ischaemia. Interesting patterns between the early phase (perfusion) and the late phase (receptor distribution) were found. These patterns are indicative of the heterogeneous development of cerebral ischaemia where, even days after stroke onset, areas of hypoperfusion but preserved neuronal integrity may be present. However, the evaluation of the potential clinical and therapeutic impact of individual IMZ distribution patterns requires further investigation.

UNLABELLED:Somatostatin receptor scintigraphy (SRS) using 111In-octreotide has proven useful in the preoperative discrimination of expansive central nervous system lesions. Meningiomas, generally expressing human somatostatin receptor (hsst) on their surface, were detected with a sensitivity of about 100%. This finding was associated with the assumption that meningiomas lack an intact blood-brain barrier. However, this exclusion procedure became questionable when histologically proven meningiomas in which SRS was negative were reported. Therefore, the aim of this study was to discover why these meningiomas gave negative SRS results.METHODS:Before surgery, 46 patients with 47 meningiomas underwent standard MRI and SRS. Thirty-four of these patients with 35 tumors were also examined by 99mTc-diethylenetriaminepentaacetic acid (DTPA) brain scintigraphy. After surgical resection, hsst subtype 2 (hsst2) messenger RNA (mRNA) expression of 4 SRS-positive and 4 SRS-negative meningiomas was estimated semiquantitatively by reverse transcriptase polymerase chain reaction (RT-PCR). Translation of hsst2 mRNA into receptor proteins was proven immunocytochemically on the surface of 1 SRS-positive and 1 SRS-negative meningioma. Tumor specimens used for RNA extraction and RT-PCR and cultivated cells used for hsst2 immunostaining were tested for their meningioma nature by immunochemistry.RESULTS:SRS yielded positive results in 39 meningiomas with a tumor volume of 24.1 +/- 32.8 mL and negative results in 8 meningiomas with a volume of 3.9 +/- 6.5 mL. 99mTc-DTPA scintigraphy visualized 24 of 35 meningiomas. SRS was positive in all of them. In contrast, 11 meningiomas were (99mTc-DTPA negative. In these meningiomas, SRS was negative in 5 cases (5.4 +/- 8.1 mL), whereas the remaining 6 were positive (4.6 +/- 4.5 mL). None of the meningiomas was 99mTc-DTPA positive and SRS negative. RT-PCR revealed no significant difference of hsst2 mRNA expression between SRS-positive and SRS-negative meningiomas but showed varied expression among all meningiomas regardless of SRS results. Furthermore, hsst2 proteins were visualized immunocytochemically on the surface of cultivated cells of SRS-positive and SRS-negative meningiomas.CONCLUSION:SRS-negative meningiomas do express hsst2; thus, in these meningiomas SRS is false-negative. Because an insufficient sensitivity was excluded, 99mTc-DTPA scintigraphy identified a permeability barrier in SRS-negative meningiomas that explains their false-negative SRS results. SRS-negative meningiomas most likely meet the function of their tissue of origin (the meninges) to develop more-or-less intact permeability barriers.

PURPOSE:The value of 18FDG-PET to predict the outcome after therapy in Hodgkin's lymphoma was compared to morphologic staging and ESR.PATIENTS AND METHODS:A total of 50 concurrent 18FDG-PET and CT studies were performed in 37 patients with Hodgkin's lymphoma. ESR was evaluated 32 times after treatment was completed.RESULTS:Out of 39 residual masses found by CT 8 relapses could be proven. Out of 11 CT exams with CR 3 relapses occurred. CT turned out to show a sensitivity, specificity, PPV, NPV, and accuracy of 72%, 21%, 21%, 73%, and 32%, with respect to predict disease-free survival (DFS). 18FDG-PET was positive in 22 examinations with 10 recurrences in this group. Out of 28 negative 18FDG-PET 1 relapse developed 3 years later. 18FDG-PET turned out to show promising sensitivity, specificity, PPV, NPV, and accuracy of 91%, 69%, 46%, 96%, 74%, with respect to predict DFS. ESR was elevated in 12 studies of which 5 relapses could be proven, while out of 20 normal ESR-studies 3 relapses occurred. Thus, ESR turned out to show sensitivity, specificity, PPV, NPV, and accuracy of 63%, 71%, 42%, 85%, and 75%, with respect to predict DFS. In summary, only 18FDG-PET was able to predict DFS statistically significant.CONCLUSION:18FDG-PET can be very useful in patients with residual masses after treatment.

Hintergrund: Der okkulte Primärtumor gestaltet sich häufig als diagnostischer und therapeutischer Problemfall. Das Ziel dieser Studie war daher, den Stellenwert der Positronenemissionstomographie (PET) mit Fluordeoxyglukose (FDG) zur Detektion eines okkulten Primärtumors bei Patienten mit Lymphknotenmetastasen der Halsregion zu überprüfen. Methode: Insgesamt wurden 32 Patienten im Alter von 31–84 Jahren mit zervikalen Lymphknotenmetastasen eines bioptisch gesicherten Plattenepithelkarzinoms (n=24), eines Adenokarzinoms (n=2), eines Keimzelltumors mit Chorionkarzinomanteilen (n=1) bzw. eines undifferenzierten Karzinoms (n=5) untersucht. Nach Gabe von 370 MBq FDG wurden Ganzkörperaufnahmen 60 min p.i. ohne Schwächungskorrektur an einer ECAT EXACT 47/921 akquiriert und visuell ausgewertet. Alle Befunde wurden histologisch oder durch CT/MRT evaluiert. Ergebnisse: Bei 13 der 32 Patienten konnte die PET keinen Hinweis auf einen möglichen Primärtumor geben. Im Gegensatz dazu zeigten 19/32 Patienten in der PET Primarius-suspekte Tracerakkumulationen. Diese fanden sich pulmonal (n=7), im Bereich der Tonsilla palatina (n=5), der Glandula submandibularis (n=2), des Nasopharnyx (n=1), des Larynx (n=1), supraklavikulär (n=2) sowie im Zungengrund (n=1). Bei 11 dieser 19 Patienten konnte der Primärtumor bestätigt werden. Dies betraf 5 Patienten mit einem Bronchialkarzinom, 2 Patienten mit Speicheldrüsenkarzinom bzw. jeweils 1 Patienten mit einem Primärtumor des Larynx, des Zungengrundes, des Nasopharnyx bzw. der Tonsilla palatina. Die PET war bei 6 Patienten falsch-positiv. Zwei Patienten verweigerten die weitere Abklärung des PET-Befundes. Schlussfolgerungen: In etwa einem Drittel der untersuchten Patienten konnte die PET den Primärtumor erkennen und somit das weitere therapeutische Prozedere nachhaltig beeinflussen. Daher stellt die FDG-PET eine wertvolle diagnostische Ergänzung zur Erkennung des okkulten Primärtumors bei Patienten mit Lymphknotenmetastasen der Halsregion dar.

The popular recreational drug, ‘ecstasy’, mainly contains 3,4-methylenedioxymethamphetamine (MDMA) as the psychotropic agent. MDMA is suspected of causing neurotoxic lesions to the serotonergic system as demonstrated by animal studies, examinations of human cerebrospinal fluid, and the first positron emission tomography (PET) studies using the serotonin transporter ligand [11C]-McN5652. Damage of serotonergic afferents might mediate long-lasting alterations of cerebral glucose metabolism as a secondary effect. To study a relationship between ecstasy use and long-lasting alterations, PET using 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) was performed in 93 ecstasy users and 27 subjects without any known history of illicit-drug abuse. As an index of glucose metabolism, mean normalized FDG uptake was determined in both groups using a computerized brain atlas, and was compared for a selected number of brain regions. FDG uptake was normalized in each individual by dividing local FDG uptake by the maximum FDG uptake in the individual's brain. Within the group of ecstasy users we examined the relationship between FDG uptake and cumulative ecstasy dose, time since last ecstasy ingestion at the time of PET scanning, and age at first ecstasy use, respectively. Normalized FDG uptake was reduced within the striatum and amygdala of ecstasy users when compared to controls. No statistically significant correlation of the FDG uptake and the cumulative dose of ecstasy was detected. A positive correlation was found in the cingulate between FDG uptake and the time since last ecstasy ingestion. As compared to the control group, normalized FDG uptake in the cingulate was reduced in ecstasy users who took ecstasy during the last 6 months, while it was elevated in former ecstasy users who did not consume ecstasy for more than 1 year. FDG uptake was significantly more affected in ecstasy users who started to consume ecstasy before the age of 18 years. In conclusion, ecstasy abuse causes long-lasting effects on glucose metabolism in the human brain. These effects are more severe in the case of very early abuse. However, several questions still remain to be answered, i.e. the correlation of the neuronal alterations and the history of ecstasy use (cumulative dose, and time since the last dose) and its reversibility.

UNLABELLED:99mTc-methoxyisobutylisonitrile (99mTc-MIBI) has been suggested as a tracer for the scintigraphic detection of multidrug resistance (MDR). The aim of this study was to compare MDR characteristics in vitro and in vivo by immunohistochemic and functional uptake assays in established tumor cell lines cultured and grown in severe combined immunodeficient (SCID) mice.METHODS:The presence of MDR was assessed in vitro in drug-resistant HT-29(mdr1) colon carcinoma cells and in nonresistant HT-29(par) cells by JSB-1 immunohistochemistry, uptake of the fluorescent dye Rhodamine 123, and quantitative measurement of 99mTc-MIBI accumulation. For in vivo imaging, SCID mice bearing subcutaneous xenografts of these cell lines were injected with 99mTc-MIBI and 18F-FDG for scintigraphic and PET examination. After imaging, tumors were analyzed by immunohistochemistry and electron microscopy.RESULTS:All HT-29(mdr1) cells cultured in vitro exhibited distinct JSB-1 immunoreactivity, although to a variable degree, whereas HT-29(par) cells were completely devoid of JSB-1 staining. Rhodamine 123 accumulated poorly in HT-29(mdr1) cells but strongly in HT-29(par) cells. Accumulation of 99mTc-MIBI was 0.05% +/- 0.01% of the activity of the external medium in HT-29(mdr1) cells, but about eight times higher in HT-29(par) cells (0.40% +/- 0.09%), a very low percentage compared with other tumor cell lines. No difference in 201TlCl accumulation was observed between both cell lines. In vivo, neither HT-29(par) nor HT-29(mdr1) tumors grown in SCID mice could be detected by 99mTc-MIBI scintigraphy. In FDG PET, both HT-29(mdr1) and HT-29(par) tumors were clearly visible. FDG uptake was, however, markedly higher in HT-29(par) than in HT-29(mdr1) tumors. Both tumor types were poorly vascularized, as shown histologically. JSB-1 immunoreactivity was absent in all HT-29(par) tumors examined, whereas the majority of HT-29(par) tumor cells were stained. Electron microscopy showed that HT-29(par) tumors contained significantly less mitochondria than hepatocytes of the SCID mouse liver, which displayed high 99mTc-MIBI uptake in our scintigraphy studies.CONCLUSION:Sufficient 99mTc-MIBI uptake is the major prerequisite for distinguishing successfully between drug-resistant and sensitive cells. Negative 99mTc-MIBI scintigrams are not necessarily associated with MDR expression. In some tumors, FDG may be an in vivo marker for MDR as suggested by PET.

Background. Preliminary reports suggest that PET using 18F-FDG may be a valuable diagnostic tool in patients with advanced malignant melanoma. Therefore, the aim of this study was to compare the findings of 18F-FDG-PET and those of conventional imaging including physical examination for both primary and follow- up staging of patients with malignant melanoma. Patients and methods. Thirty-five patients with histologically proven malignant melanoma underwent 61 PET examinations. After an intravenous injection of 370 MBq 18F-FDG, whole-body images were acquired on an ECAT EXACT 47 (921) with an axial field-of-view of 16.2 cm. Moreover, all patients underwent physical examination and conventional imaging, i.e. ultrasound, CT, and MRI within a two-week interval after 18F-FDG-PET. Based on the findings of both staging procedures, the patients were classified according to UICC. Results. In primary staging or follow-up, 5 out of 35 patients were classified as stage I by conventional staging. Seven out of 35 patients were classified as stage II. The remaining 23 patients were initially classified as stage III. In the follow-up, two out of the latter 23 patients were upstaged to stage IV. However, none of these patients was classified as stage IV in primary staging by conventional diagnostic procedures. According to the results of 18F-FDG-PET, 9 out of 35 patients revealed neither evidence for distant metastases nor presence of lymph node metastases in primary staging (stage I/II). However, initially 21 out of 35 patients were suspected for lymph node metastases but no distant metastases (stage III). Moreover, 18FFDG- PET suspected 5 patients, initially classified as stage IV, for distant metastases. However, in the follow- up, 18F-FDG-PET turned out to be false-positive for distant metastases in one out of the latter 5 patients; therefore, this patient was staged down to stage III. As compared to conventional diagnostic work-up, 18F-FDG-PET revealed the corresponding tumor stage in 17 out of 35 patients (49 %). However, 14 patients (40%) were staged up by 18F-FDG-PET and 4 patients (11%) were staged down by 18F-FDG-PET in primary staging or follow-up investigations. With respect to anatomical localization, the majority of false-negative PET lesions were lymph node metastases close to the skin area. Conclusions. Our results underline the added value of 18F-FDG-PET in staging of malignant melanoma. Since further treatment mainly depends on the clinical stage, 18F-FDG-PET might help to select the appropriate treatment protocol for each individual patient.

Resectional surgery offers a curative intent and a survival benefit for patients with hilar cholangiocarcinoma, but is associated with high morbidity. Since morphological imaging cannot solve differential diagnosis preoperatively, in order to exclude patients inappropriate to this aggressive surgery, we evaluated the impact of functional imaging using fluorodeoxyglucose positron emission tomography (FDG PET) in the detection of cholangiocarcinoma and its usefulness in the differentiation from benign Klatskin tumour-mimicking lesions. Fifteen consecutive patients aged 47-78 years underwent standardized whole-body FDG PET with attenuation correction before potentially curative surgery using a conventional full-ring PET scanner with an axial field-of-view of 16.2 cm. FDG PET was evaluated visually and semiquantitatively using tumour-to-background ratios (T/B) ratios. All lesions were evaluated histopathologically. FDG PET presumed to be indicative for carcinoma was positive in 12 of 15 patients, true positive in 10 (T/B ratio, 3.2+/-1.9) and false positive in two of them (T/B ratios, 2.1 and 2.8) with Klatskin tumour-mimicking lesions. While all true positive PET results were seen in the tubular type of cholangiocarcinoma with a high amount of tumour cells and only low production of mucus, a false negative FDG PET in three patients was observed in mucinous adenocarcinoma. Additionally, FDG PET detected locoregional lymph nodes in two patients and distant metastases in a further three patients. Due to false positive results FDG PET does not allow the differentiation of benign from malignant lesions, and FDG PET should be avoided in patients with mucinous cholangiocarcinoma. However, FDG PET may have significant influence on the treatment strategy in as much as 20% of the patients, since it may detect distant metastases.

Summary Aim: The prevalence of iodine- and thyroglobulin-nega-tive findings was evaluated in all patients with differentiated thyroid cancer (DTC) treated from 1961 until 1998 at the Department of Nuclear Medicine, University Hospital Hamburg-Eppendorf. Methods: A total of 490 patients with papillary thyroid cancer (PCA) and 242 patients with follicular thyroid cancer (FCA) were analyzed retrospectively. Patients were divided into four groups: 1: no recurrence, 2: recurrent disease, 3: primary metas-tatic/progressive disease and 4: inconclusive follow-up. Results of iodine scan, serum-TG, and additional imaging modalities as well as histology were compared in all patients. Results: 21/490 (4,3%) of patients with PCA and 16/242 (6,6%) with FCA suffered from recurrent disease. 62/490 (12,7%) of patients with PCA and 59/242 (24,4%) with FCA had primary metastatic/progressive disease. 12/21 patients with PCA and 12/16 with FCA showing up with recurrent disease had a negative iodinescan. 11/21 of patients with PCA and 4/16 with FCA and tumor recurrence had negative serum-TG levels. 14/62 patients with PCA and 14/59 with FCA presenting with primary metastatic/ progressive disease had negative iodinescan. 14/62 patients with PCA and 6/59 with FCA had negative serum-TG. Conclusion: The prevalence of iodine-negative recurrent"/metastatic disease is in accordance to the literature, whereas the prevalence of TG-negative recurrent/metastatic was noted higher than reported previously. Thus, the commonly used follow-up scheme of DTC is confirmed. However, iodine scan should be regularly performed in patients with high risk of recurrence.

UNLABELLED:FDG PET is increasingly performed in patients with differentiated thyroid cancer who present with elevated human thyroglobulin (hTG) levels and negative 131I scan. The aim of this study was to evaluate the impact of FDG PET on treatment in these patients. METHODS:A total of 118 FDG PET studies were performed on 64 patients, and follow-up data were available for all patients. Whole-body images were acquired 1 h after intravenous injection of 370 MBq (10 mCi) FDG using a PET scanner with an axial field of view of 16.2 cm. Tumor-suspicious FDG PET studies were evaluated by histology, cytology, 131I uptake, CT or MRI, and follow-up of hTg levels. The therapeutic consequence was noted for each patient. Moreover, results of FDG PET were correlated with hTg levels. RESULTS:Forty-four patients had positive scans, which were proven to be true-positive in 34 patients, whereas 7 patients had false-positive findings. Two patients exhibited a secondary malignancy. One patient did not fit in any category, having true-positive, false-positive, and false-negative findings. On the other hand, 20 patients had negative scans. These were true-negative findings in 5 patients, whereas the remaining 15 patients had false-negative results. Accordingly, the positive predictive value of FDG PET was 83% (34/41), whereas the negative predictive value was 25% (5/20). Treatment was directly changed in 19 of 34 patients with true-positive PET studies: 18 patients had further surgery, and 4 patients were referred for external irradiation, 3 of them after incomplete removal of local recurrences. FDG PET showed widespread disease in 7 patients; thus, palliative treatment, rather than curative therapy, was initiated. True-positive FDG PET findings were correlated positively with increasing hTg levels (i.e., FDG PET was true-positive in 11%, 50%, and 93% of patients with hTg levels of <10, 10-20, and >100 microg/L, respectively). CONCLUSION:FDG PET is a valuable diagnostic tool in patients with differentiated thyroid cancer who present with increased hTg levels and negative 131I scans because it permits selection of patients for surgery, which may be curative. FDG PET is most promising at hTg levels of >10 microg/L.

In the last decade, the market of nuclear medicine instrumentation has developed dramatically. On the one hand, highly sophisticated equipment has been introduced, which allows procedures like transmission measurement for image fusion, attenuation correction, scatter correction and automatic body contouring. On the other hand there is a significant demand for imaging facilities at lower costs for routine diagnostics. Since both tendencies are accompanied by an increasing number of mergers, the number of industry partners has been decreasing continuously over the last few years. The present paper focuses on basic requirements for stateof-the-art gamma cameras and briefly discusses upcoming developments in the field of nuclear medicine instrumentation.

SummaryIn 1995, the management of the University Clinic Hamburg-Eppendorf proposed to establish a total quality assurance (QA) system. A revised QA-system has been introduced stepwise in the department of nuclear medicine since 1997, and certification was achieved in accordance with DIN EN ISO 9001:2000 on February 14,2001.The QA-handbook is devided into two parts. The first part contains operational (diagnostic and therapeutic) procedures in so-called standard operating procedures (SOP). They describe the indication of procedures as well as the competences and time necessary in a standardized manner. Up to now, more than 70 SOPs have been written as a collaborative approach between technicians and physicians during daily clinical routine after analysing and discussing the procedures. Thus, the results were more clearly defined processes and more satisfied employees.The second part consists of general rules and directions concerning the security of work and equipment as well as radialion protection tasks, hygiene etc. as it is required by the law. This part was written predominantly by the management of the department of nuclear-medicine and the QA-coordinator. Detailed information for the patients, documentation of the work-flows as well as the medical report was adapted to the QM-system. Although in the introduction phase of a QA-system a vast amount of time is necessary, some months later a surplus for the clinical workday will become available. The well defined relations of competences and procedures will result in a gain of time, a reduction of costs and a help to ensure the legal demands. Last but not least, the QA-system simply helps to build up confidence and acceptance both by the patients and the referring physicians.