[Bone scintigraphy. German Guideline S1]. / Skelettszintigraphie. DGN-Handlungsempfehlung (S1-Leitlinie).

The purpose of this guideline is to provide comprehensive state-of-the-art information about indication and how to perform and analyze bone scintigraphy. Based upon pathophysiology and pharmacology current acquisition techniques including new methodologies are summarized followed by a detailed list of indications. In the main part all relevant practical aspects such as patient preparation, anamnestic information, appropriate choice and dosage of the radiopharmaceutical, and data acquisition including interventions are discussed. Data processing and analysis, interpretation, reporting and documentation are described in the next chapters. Quality control, typical pitfalls and a short outlook to future developments complete the guideline.

Multi-centre calibration of an adaptive thresholding method for PET-based delineation of tumour volumes in radiotherapy planning of lung cancer.

PURPOSE: To evaluate the calibration of an adaptive thresholding algorithm (contrast-oriented algorithm) for FDG PET-based delineation of tumour volumes in eleven centres with respect to scanner types and image data processing by phantom measurements. METHODS: A cylindrical phantom with spheres of different diameters was filled with FDG realizing different signal-to-background ratios and scanned using 5 Siemens Biograph PET/CT scanners, 5 Philips Gemini PET/CT scanners, and one Siemens ECAT-ART PET scanner. All scans were analysed by the contrast-oriented algorithm implemented in two different software packages. For each site, the threshold SUVs of all spheres best matching the known sphere volumes were determined. Calibration parameters a and b were calculated for each combination of scanner and image-analysis software package. In addition, "scanner-type-specific" calibration curves were determined from all values obtained for each combination of scanner type and software package. Both kinds of calibration curves were used for volume delineation of the spheres. RESULTS: Only minor differences in calibration parameters were observed for scanners of the same type (Δa ≤4%, Δb ≤14%) provided that identical imaging protocols were used whereas significant differences were found comparing calibration parameters of the ART scanner with those of scanners of different type (Δa ≤60%, Δb ≤54%). After calibration, for all scanners investigated the calculated SUV thresholds for auto-contouring did not differ significantly (all p>0.58). The resulting sphere volumes deviated by less than -7% to +8% from the true values. CONCLUSION: After multi-centre calibration the use of the contrast-oriented algorithm for FDG PET-based delineation of tumour volumes in the different centres using different scanner types and specific imaging protocols is feasible.

[Nuclear Medicine in Germany. Key data from official statistics]. / Nuklearmedizin in Deutschland. Kennzahlen aus offiziellen Statistiken.

AIM: To explain the spectrum and number of in-vivo nuclear medicine examinations and therapies based on official statistics about out-patient and in-patient care. Trends in time of the frequency and spectrum of procedures as well as data on the health care structure for nuclear medicine in Germany should be collected. METHODS: Data from the Gesundheitsberichterstattung des Bundes, from the frequency statistics of the statutory health insurance for out-patients and from the Bundesärztekammer were used. Customized queries were performed to analyse temporal changes. RESULTS: Nuclear medicine physicians are more frequently consulted by out-patients over the last years (2008: 2024498; 2009: 2164664) and the number of colleagues in private practice increased. For in-patients, the frequency of conventional nuclear medicine procedures (mainly for brain, lymphatic system, lung and heart) increased since 2008 after a decline in previous years (2009: 323515; +4.6%) and the number of PET(/CT) examinations continued to rise (2009: 25123; +18%), even if changes in OPS keys may hamper comparisons. Nearly 600 gamma cameras and 76 PET(/CT) scanners were installed in hospitals in 2008. Nuclear medicine procedures are increasingly performed as cross sectional imaging like SPECT(/CT) and PET(/CT). With the supply shortfall with 99Mo, the frequency of thyroid scans with 123I iodine increased as well as the use of 18F PET as a substitute for conventional bone scans. The number of radionuclide therapies, in particular non-thyroid treatments, increased since the mid-nineties and stabilized at nearly 50000 cases per year with shorter lengths of stay. CONCLUSION: The details of the present analysis may help to understand the positive evolution of key numbers for nuclear medicine.

Retrospective web-based multicenter evaluation of ¹8F-FDG-PET and CT derived predictive factors. Radioimmunotherapy with yttrium-90-ibritumomab tiuxetan in follicular non Hodgkin's lymphoma.

AIM: Although predictive factors (PF) for conventional lymphoma therapy are established and frequently used in clinical practice and medical research, the PF for radioimmunotherapy (RIT) have not been fully defined until now. The aim of this multicenter evaluation is to prove the feasibility of the multicenter web-based data collection and to preliminary explore imaging findings and prediction of therapy response in patients with follicular lymphoma (FL) following radioimmunotherapy (RIT) with 90Y-ibritumomab tiuxetan. PATIENTS, METHODS: We retrospectively analyzed and correlated clinical and imaging data (CT and FDG-PET) before and after RIT as documented by the RIT-Network. Evaluation of treatment response was done on both patient and lesion basis. Every measurable lesion was analyzed in terms of standardized uptake value (SUV), volume (CT and PET) and response. PF were identified using a uni- and multivariate model. A web-based system was used for the documentation and evaluation of clinical and imaging data. RESULTS: 16 patients with at least one PET before and after RIT were eligible for analysis. Concerning response three months postRIT, 5 patients achieved a CR, 6 patients a PR and 4 patients remained with NC. A total of 159 lesions were measured (mean 10±8). In the multivariate model the log lesion volume (p < 0.0001), the total (p = 0.03) and maximum lesion volume (p = 0.05) were predictors for response (CR + PR). Concerning the lesional CR initial small lesion volume (p = 0.009) and its high metabolic activity (p = 0.01) were identified as predictors. The web-based system showed no major disturbances allowing secure data transfer and central image interpretation in a reasonable time. CONCLUSION: The use of a web-based multicenter archiving system for clinical and imaging data is technically feasible in a multicenter setting and allows a central analysis. This preliminary analysis suggests that FDG-PET may predict the likelihood of response to RIT.

Physical aspects of scintigraphy-based dosimetry for nuclear medicine therapy.

In nuclear medicine therapy the treatment of tumours by radiation exposure from internally deposited labelled antibodies or labelled peptides is currently an active field of investigation. To permit the efficient delivery of high amounts of radiation dose to tumours while limiting the radiation dose to critical organs dosimetry calculations have to be performed. These are relying on scintigraphic data being input to the well known MIRD formalism. This paper focuses on the methods and the difficulties associated with the scintigraphic determination of organ kinetics. The physical properties of the well-known scintigraphic imaging modalities, PET, SPECT and planar scintigraphy, are discussed thereby taking into account the properties of the appropriate radionuclides currently being available for therapy and dosimetry. Several arguments are given and disputed for the limited clinical use of PET and SPECT in dosimetry and the ongoing preference of planar whole-body imaging as the method of choice. The quantitative restrictions still inherent to this method are also discussed in detail. Procedural recommendations are proposed covering all processes related to data acquisition, data correction and data analysis which finally lead to reliable estimations of organ dose.

Para-[(123)I]iodo-L-phenylalanine in patients with pancreatic adenocarcinoma: tumour uptake, whole-body kinetics, dosimetry.

UNLABELLED: Recently, p-[(123)I]iodo-L-phenylalanine (IPA) was clinically validated for brain tumour imaging. Preclinical studies demonstrated uptake of IPA into pancreatic adenocarcinoma suggesting its diagnostic application in patients with pancreatic tumours. The aim was to study the tumour uptake of IPA in patients with pancreatic adenocarcinoma and to analyse its biodistribution and dosimetry to assess the radiation dose resulting from its diagnostic use. PATIENTS, METHODS: Seven patients with pancreatic adenocarcinoma underwent whole-body scintigraphies and SPECT up to 24 h after administration of 250 MBq of IPA. Tumour uptake of IPA was assessed visually. Time activity curves and the corresponding residence times were determined for whole-body, kidneys, liver, spleen, lung, heart content, brain, and testes. Mean absorbed doses for various organs and the effective dose were assessed based on the MIRD formalism using OLINDA/EXM. RESULTS: IPA exhibited no accumulation in proven manifestations of pancreatic adenocarcinomas. IPA was exclusively eliminated by the urine and showed a delayed clearance from blood. Residence times were 0.26 +/- 0.09 h for kidneys, 0.38 +/- 0.19 h for liver, 0.15 +/- 0.07 h for spleen, 0.51 +/- 0.20 h for lungs, 0.22 +/- 0.07 h for heart content, 0.11 +/- 0.05 h for brain, 0.014 +/- 0.005 h for testes and 6.4 +/- 2.2 h for the remainder. The highest absorbed doses were determined in the urinary bladder wall and in the kidneys. According to the ICRP 60 the effective dose resulting from 250 MBq IPA was 3.6 +/- 0.7 mSv. CONCLUSION: Para-[(123)I]iodo-L-phenylalanine can be used in diagnostic nuclear medicine with acceptable radiation doses. Besides its proven validity for brain tumour imaging, IPA does not appear to be suitable as tracer for pancreatic cancer.

Striatal FP-CIT uptake differs in the subtypes of early Parkinson's disease.

In idiopathic Parkinson's disease (PD), a tremor-dominant type (TDT), an akinetic-rigid type (ART), and a mixed type (MT) are distinguished. We compared cerebral [I-123]FP-CIT SPECT in the PD subtypes (67 patients Hoehn and Yahr stage 1:26 with ART, 19 with MT, 22 with TDT). We measured the ratios putamen/occipital lobe binding and caudate nucleus/occipital lobe binding. Parkinsonian motor symptoms were quantified by UPDRS motor scale. In both putamen and caudate nucleus contralateral to the clinically affected body side TDT patients showed a significantly higher FP-CIT uptake than ART or MT patients (ANOVA; p<0.01). Contralateral putamen and caudate nucleus FP-CIT uptake correlated significantly with severity of rigidity (p<0.01) and hypokinesia (p<0.01) but not with severity of resting or postural tremor (p>0.05). The missing correlation between striatal FP-CIT uptake and tremor suggests, that further systems besides the nigrostriatal dopaminergic system may contribute to generation of parkinsonian tremor.

[Positron emission tomography and scintigraphy. Nuclear imaging in clinical orthopaedics]. / Positronenemissionstomographie und Szintigraphie. Nuklearmedizinische Verfahren in der Orthopädie.

Nuclear medicine uses the function of organs or organ systems to diagnose and treat disease. The source of radiation is brought into the patient's body by means of a radioactive labelled pharmaceutical. Its way through the body is recorded by appropriate equipment on the outside. Of the many nuclear medical procedures, those primarily applicable to orthopaedic problems are explained here, such as bone scintigraphy, scintigraphy of inflammatory lesions, and tumour scintigraphy. Besides their use in diagnostics, therapeutic applications are covered as well. Using examples from clinical practice, "conventional" nuclear medicine and positron emission tomography are also covered.

[Guideline for therapy of malignant thyroid tumours: pleading for an actualization]. / Leitlinie zur Therapie maligner Schilddrüsentumoren: Plädoyer für eine Aktualisierung.

Total (or near total) thyroidectomy (TE) followed by radioiodine ((131)I) ablation (RIA) of residual thyroid tissue is considered to be the ideal treatment for differentiated thyroid carcinoma. However, the actual guideline of the DGN (German Society of Nuclear Medicine) recommends for the so-called papillary micro-carcinoma of the thyroid (PMC) no further therapeutic strategy (no complete TE, no (131)I-ablation of the remaining lobe). PMC has been defined as papillary carcinoma measuring 1 cm (T1) in maximal diameter according to the World Health Organization classification system for thyroid tumours (1988). The new WHO-classification (starting in 2003) defines the T1-tumour measuring 2 cm in maximal diameter. The authors demand a new, modern guideline, following the new WHO classification. This includes, that despite the overall excellent prognosis for patients with PMC, the treatment of patients with T1-tumours of the new WHO-classification (including the "old" PMC) should be no different from the treatment of patients with conventional papillary thyroid carcinoma, i.e. complete surgery (TE and central lymph node dissection) followed by RIA of residual thyroid tissue. The authors argue that it is not appropriate to consider the tumour size as the single most important key factor for therapy and prognosis. Even small tumours may have poor prognostic factors, such as lymph node metastasis, multifocality or molecular characteristics (expression of oncogenes).

[PET with (18)F-fluorodeoxyglucose for staging of non-small cell lung cancer]. / PET mit (18)F-Fluordeoxyglukose in der Diagnostik des nicht kleinzelligen Bronchialkarzinoms: evidenzbasierte Empfehlungen und Kosten/Nutzenabwägungen.

AIMS: To evaluate studies on the use of positron emission tomography with the glucose analog (18)F-fluoro-deoxyglucose (FDG-PET) for the preoperative staging of patients with non-small cell lung cancer (NSCLC) according to the criteria of evidence based medicine and to discuss the cost-effectiveness of the technique. METHODS: Clinical studies published between 1995 and 2002 on the preoperative staging of non-small cell lung cancer were used for this analysis. Studies that did not meet the criteria published by the European Agency for the Evaluation of Medicinal Products (EMEA) were excluded. The validity of the studies was evaluated by a standardized rating system developed by the Agency for Health Care Policy and Research (AHCPR). RESULTS: For the detection of mediastinal lymph node metastases the mean sensitivity and specificity of FDG-PET on a patient basis is 85% and 87% (16 studies, 1355 patients). In studies that compared FDG-PET and computed tomography (CT) the mean sensitivity of CT was 66% at a specificity of 71%. In the detection of distant metastases FDG-PET correctly changed the tumor stage in 18% of the patients when compared to CT based staging (10 studies, 1073 patients). Five cost effectiveness analyses from the USA, Japan, and Germany concluded that FDG-PET improves the outcome of treatment at reduced or only slightly increased overall costs. Improvement of patient outcome was also demonstrated in a randomized trial, which found that the risk of a futile thoracotomy was reduced by 51% (p=0.003) when FDG-PET was added to the preoperative staging. CONCLUSION: According to the criteria of the AHCPR the use of FDG-PET for detection of mediastinal lymph node and distant metastases is documented at a level of evidence Ia and Ib, respectively. Since systematic analyses also indicate a favorable cost-effectiveness ratio FDG-PET has to be considered as "strictly indicated" for the preoperative staging of non-small cell lung cancer.

[Optimization of radiotherapy planning for non-small cell lung cancer (NSCLC) using 18FDG-PET]. / Optimierung der Bestrahlungsplanung beim nicht-kleinzelligen Bronchialkarzinom (NSCLC) mit Hilfe von 18FDG-PET.

AIM: In recent years, FDG-PET examinations have become more important for problems in oncology, especially in staging of bronchogenic carcinoma. In the retrospective study presented here, the influence of PET on the planning of radiotherapy for patients with non-small-cell lung cancer (NSCLC) was investigated. METHODS: The study involved 39 patients with NSCLC who had been examined by PET for staging. They received radiotherapy on the basis of the anterior/posterior portals including the primary tumour and the mediastinum planned according to CT- and bronchoscopic findings. The results of the PET examination were not considered in initial radiotherapy planning. The portals were retrospectively redefined on the basis of FDG uptake considering the size and localization of the primary tumour; and FDG activities outside the mediastinal part of the portals. RESULTS: In 15 out of 39 patients, the CT/PET-planned portals differed from the CT-planned ones. In most causes (n = 12) the CT/PET field was smaller than the CT field. The median geometric field size of the portals was 179 cm2, after redefinition using PET 166 cm2. In 20 patients with disturbed ventilation caused by the tumour (atelectasis, dystelectosis), a correction of the portal was suggested significantly more frequently than in the other patients (p = 0.03). CONCLUSIONS: Our results demonstrate the synergism of topographical (CT) and metabolic (FDG-PET) information, which could be helpful in planning radiotherapy of bronchial carcinoma, especially for patients with disturbed ventilation.

Initial evaluation of the feasibility of single photon emission tomography with p-[123 I]iodo-L-phenylalanine for routine brain tumour imaging.

p-[123I]iodo-L-phenylalanine (IPA) is a recently described radiopharmaceutical which is highly accumulated in gliomas. The present investigation was designed to evaluate the feasibility of single photon emission tomography (SPET) with IPA to image brain tumours under routine clinical conditions. Using a dual- and a triple-headed SPET camera, whole-body kinetic and brain SPET, as well as plasma, urinary and dosimetric analysis were determined in four patients with gliomas after intravenous injection of IPA. Results obtained by IPA SPET were retrospectively compared with histopathology, magnetic resonance imaging and positron emission tomography with [18F]fluorodeoxyglucose. Tumour lesions were clearly demonstrated by IPA SPET at 30 min, 1h and 4.5h post-injection, even in patients with low grade gliomas. In patients with glioblastoma, excellent visualization of the tumour was possible even at 7h p.i., indicative of the high retention of the radiopharmaceutical in cerebral gliomas. Analysis of the radioactivity in plasma and urine attested to the high in vivo stability of IPA. Blood clearance was rapid (> 65% after 10 min) and IPA was excreted predominantly by the kidneys, the urinary radioactivity excretion ranging from 27% at 1h to 54% of injected doses at 5h p.i. The average effective dose for adults was estimated to be 0.0152mSv*MBq(-1), leading to an effective dose of 3.8mSv in a typical brain SPET investigation with 250 MBq IPA. This result strongly suggests that IPA is a potentially valuable brain tumour imaging agent for widespread clinical studies with SPET. Its high specific tumour uptake and retention even in low grade gliomas represent a major advantage compared to presently available SPET radiopharmaceuticals. Moreover, the radiation dose estimates indicate that clinical use of IPA will result in acceptable radiation dose levels in humans.

Utility of fiberoptic bronchoscopy before bronchial artery embolization for massive hemoptysis.

OBJECTIVE: We wanted to investigate the utility of performing fiberoptic bronchoscopy before bronchial artery embolization in patients with massive hemoptysis. MATERIALS AND METHODS: We retrospectively reviewed the cases of all patients with hemoptysis who had presented at either of two local hospitals, one county hospital and one community hospital, between 1988 and 2000 and who had undergone fiberoptic bronchoscopy before bronchial arteriography. All data were abstracted using a standardized coding form, and radiographs were independently reviewed by two of the authors. RESULTS: Twenty-nine patients meeting the inclusion criteria were identified; one patient was excluded because of missing radiographs. The remaining 28 patients consisted of 19 men and nine women, with an average age of 54.6 years (age range, 16-91 years). The clinically determined diagnoses of their symptoms were tuberculous bronchiectasis (n = 14; 50.0%); bronchogenic carcinoma (n = 4; 14.3%); active tuberculosis (n = 2; 7.1%); nontuberculous bronchiectasis (n = 2; 7.1%); active coccidioidomycosis, pancreaticobronchial fistula, arteriovenous malformation, and tetralogy of fallot (n =1 each; 3.6% each); and unknown cause (n = 2; 7.1%). The bleeding site determined through bronchoscopy was consistent with that determined through radiographs in 23 patients (82.1%); all had either unilateral disease (n = 15), bilateral disease with unilateral cavities (n = 5), or a preponderance of disease on one side (n = 3). Bronchoscopy was an essential tool in determining the bleeding site in only three patients (10.7%), all of whom had bronchiectasis without localizing features visible on chest radiographs. In the remaining two patients (7.1%), bronchoscopic findings were indeterminate, but radiographs were helpful. CONCLUSION: Fiberoptic bronchoscopy before bronchial artery embolization is unnecessary in patients with hemoptysis of known causation if the site of bleeding can be determined from radiographs and no bronchoscopic airways management is needed.

[Accuracy of positron emission tomography with fluorine-18-fluoro-deoxyglucose]. / Aussagekraft der Positronen-Emissions-Tomographie mit F-18-Fluordesoxyglukose (FDG-PET) beim Bronchioloalveolarzellkarzinom (BAC).

BACKGROUND: : FDG-PET is a powerful tool for the diagnostic workup of patients with lung cancer. A reduced sensitivity of FDG-PET for the evaluation of lung lesions was reported for bronchioloalveolar carcinoma (BAC). No literature exists about the diagnostic efficacy of FDG-PET in the staging of BAC. METHODS: : Out of a series of subsequent 630 untreated patients with the final diagnosis of lung cancer, who underwent FDG-PET, all patients with BAC were evaluated with respect to tumour detection, N-staging, and M-staging. RESULTS: : 35 patients (5.6 %) had BAC, 22 in a localized form (8 x pT1, 14 x pT2), 13 in a disseminated stage. FDG-PET correctly identified 19/22 cases with localized forms. Two of the missed one were classified as pT1. All disseminated forms of BAC were detected. Standardized uptake values (SUV) ranged from 0.9 to 23.3 (mean +/- SD: 11.6 +/- 5.1). Accuracy of N-staging was comparable to known results in lung cancer (FDG-PET 80 %, CT 64 %). With respect to M-staging, sensitivity of FDG-PET was as follows: M1(HEP): 2/3 (67 %), M1(PUL): 7/8 (88 %), M1(OSS): 1/1 (100 %). CONCLUSIONS: : With some limitations in small localized tumours FDG-PET can detect and stage BAC with an accuracy which is identical to that for other histological types of non-small cell lung cancer.

[Meta-analysis of the efficacy of positron emission tomography with F-18-fluorodeoxyglucose in lung tumors. Basis for discussion of the German Consensus Conference on PET in Oncology 2000]. / Metaanalyse zum Stellenwert der Positronen-Emissions-Tomographie mit F-18-Fluorodesoxyglukose (FDG-PET) bei Lungentumoren. Diskussionsbasis der deutschen Konsensus-Konferenz Onko-PET 2000 -

BACKGROUND: : To analyse current literature on FDG-PET for evaluation of lung lesions, N-staging, M-staging, and recurrence of lung cancer for the third German Consensus Conference on PET in oncology. METHODS: Specialists in nuclear medicine, pneumology, radiation oncology, diagnostic radiology, and thoracic surgery reviewed the relevant literature as listed in MEDLINE from 1985 to 1999 for further analysis. Out of the published data cumulative test parameters and summary receiver operating characteristic curves (sROC curves) were computed. RESULTS: Sensitivity, specificity, and accuracy of FDG-PET are 96 %, 80 %, 91 % for evaluating lung lesions (15 studies with at least 35, in total 1144 patients). With corresponding values of 88 %, 92 %, 91 % (20 studies, 1292 patients) for N-staging FDG-PET is superior to CT with 65 %, 76 %, 73 % (19 studies, 1268 patients). With 94 %, 97 %, 96 % (4 studies, 336 patients) M-staging with FDG-PET is very accurate and changed therapeutic management in 18 % of the cases (8 studies, 695 patients), unexpected extrathoracic metastases were found in 12 % (7 studies, 581 patients). FDG-PET is the most accurate non-invasive method to evaluate suspected adrenal metastases (3 studies, 263 patients, sensitivity 96 %, specificity 99 %, accuracy 98 %). Recurrence is detected accurately (4 studies, 224 patients, sensitivity 99 %, specificity 89 %, accuracy 95 %). CONCLUSIONS: Studies with in total more than 1000 patients show the high diagnostic efficacy of FDG-PET and its superiority to conventional imaging in lung cancer. Based on this analysis the third German Consensus Conference on PET in oncology evaluated FDG-PET on lung cancer. 1a-indications are evaluation of lung nodules in patients at risk for complications during surgery, N-staging, M-staging (except brain), and detection of recurrence.

An unusual complication during central venous catheter placement.

A 31-year-old man with disseminated Coccidioides imitis infection required central catheter placement for access. The patient had an inferior vena cava (IVC) filter placed as a result of previous deep venous thrombosis of the left lower extremity. The guidewire could not be removed following placement of the right internal jugular catheter by the Seldinger technique. Fluoroscopic examination revealed entanglement of the J-tip guidewire in the apex of the IVC filter. The catheter was successfully removed by interventional radiologists using a snare tip catheter through the left femoral vein.

Preparation and investigation of tumor affinity, uptake kinetic and transport mechanism of iodine-123-labelled amino acid derivatives in human pancreatic carcinoma and glioblastoma cells.

In developing radioiodinated agents for pancreatic and brain tumor imaging by single photon emission tomography (SPET), we prepared p-amino-3-[123I]iodo-l-phenylalanine (IAPA), p-[123I]iodo-l-phenylalanine (IPA), L-8-[123I]iodo-1,2,3,4-tetrahydro-7-hydroxyisoquinoline-3-carboxylic acid (ITIC) and L-3-[123I]iodo-alpha-methyl-tyrosine (IMT) in radiochemical yields up to 95%, and we investigated their uptake in human pancreatic carcinoma and glioblastoma cells as well as the mechanisms promoting the tumor uptake. The radiopharmaceutical uptake into tumor cells was rapid (t(1/2) < or = 5 min) and temperature- and pH-dependent. The radioactivity concentration in tumor cells varied from 10 to 33% of the total activity (105-310 cpm/1000 cells) following a 30-min incubation at 37 degrees C (pH 7.4). In comparison, accumulation of the radiopharmaceuticals into normal brain and pancreatic tissue remained relatively low. Depolarizing the plasma membrane potential in high K+ buffer significantly altered the radioactivity concentration in the tumor cells, suggesting that membrane potential plays a certain role in the cellular uptake. Competitive inhibition experiments with specific amino acid transport inhibitors indicated that the uptake of IAPA, IPA and IMT into human pancreatic carcinoma and glioblastoma cells is predominantly mediated by the L and ASC transport systems, while no substantial involvement of the transport system A in their tumor uptake could be demonstrated. In contrast, results of the present investigation indicated that ITIC is not taken up into tumor cells via the common neutral amino acid carrier systems, including the A, L and ASC system. Furthermore, preloading with naturally occurring L-amino acids failed to stimulate the cellular uptake of the radiopharmaceuticals. These data indicate that the investigated radiopharmaceuticals exhibit interesting characteristics with promise for in vivo tumor investigations to ascertain their potential as radioligands for glioma and pancreatic carcinoma imaging by SPET.

[Kinetics and dosimetry of monoclonal antibody MAb-170: evaluation of possibilities for intraperitoneal radioimmunotherapy]. / Biokinetik und Dosimetrie mit dem monoklonalen Antikörper MAb-170: Evaluation der Möglichkeit einer intraperitonealen Radioimmuntherapie.

UNLABELLED: The monoclonal antibody MAb-170 is directed against adenocarcinomas of different origin. Recent experience in radioimmunoscintigraphy revealed a positive uptake of this MAb in peritoneal metastases of ovarian carcinoma (FIGO III/IV). AIM: The present investigation should clarify the question whether this antibody could be of use in an adjuvant intraperitoneal radioimmunotherapy (RIT) in patients with minimal residual disease after first-look surgery. METHODS: Four patients underwent intraperitoneal application of Tc-99m MAb-170. Subsequent quantitative whole-body scintigraphy, serum and urine sampling were performed for a 48 h period. In one case tumour tissue specimen were sampled during the first surgical procedure 15 h p.i.. RESULTS: The quantitative evaluation revealed no relevant accumulation in liver, spleen and bone marrow never exceeding 5% of the whole-body activity. The critical organs are the kidneys that showed 8 to 11% uptake at 24 h p.i.. The effective serum curve had a maximum at 24 h p.i., the second phase gave a elimination half-time of 53 h. Assuming the worst case, the mean dose to red bone marrow was 0.3 Gy/370 MBq injected dose (ID). CONCLUSION: These results confirm that a RIT with Re-186 MAb-170 is feasible with activities of up to 3.7 GBq. A kit for labelling MAb-170 with Perrhenate is under investigation.

Successful low-dose intracavitary irradiation of a Rathke's cleft cyst with colloidal rhenium-186.

Symptomatic recurrence of an histologically verified intra- and suprasellar Rathke's cleft cyst (RCC) was observed 4 months following transsphenoidal microsurgery. The space-occupying cyst was treated by endocavitary irradiation with colloidal rhenium-186 via a previously implanted catheter with an attached subcutaneous reservoir. The calculated dose of 4.4 Gy was able to stop the production of cyst fluid. Follow-up after intracavitary irradiation extends over 13 months. The cyst, with an initial size of 3 x 3 x 4 cm, has been reduced to 1.1 x 1.06 x 1.2 cm. The production of cyst fluid has decreased from 25 - 30 ml within 2 months before treatment to zero. The patient's visual and mental status as well as her quality of life are normal.

[Radiation exposure to patients caused by single-photon transmission measurement in PET]. / Die Strahlenexposition des Patienten durch die Einzelphotonen-Transmissionsmessung bei der PET.

AIM: The aim of the study was the determination of the radiation exposure to the patient caused by single-photon transmission measurement for 3D whole-body PET. MATERIAL AND METHOD: Single-photon-transmission measurement is performed using two Cs-137 point-sources (E gamma = 662 keV, A = 2*614 MBq) on a 3D PET scanner (ECAT ART). During a simulation of a whole body transmission scan (axial length: 75 cm, 6 contigous bed positions) dose measurements with thermoluminescent dosimeters were carried out using a thorax and an abdomen phantom. Following the guidelines of the ICRU report No. 60 an estimation of the effective dose caused by a single-photon transmission measurement was calculated. RESULTS: For a total acquisition time of 360 min (6 beds with an acquisition time of 60 min per bed) the absorbed doses amounted to: surface (xyphoid) 189 microGy, heart 196 microGy, lungs 234 microGy, vertebra 240 microGy, liver 204 microGy, gonads 205 microGy, thyroid 249 microGy and bladder 185 microGy resulting in a conversion factor of 1.7*10(-4) mSv/(h*MBq). The estimation of the effective dose for a patient's transmission (acquisition time of 3.2 min per bed) yields a value of 11 microSv. An estimation of the ratio of the conversion factors for transmission measurements in single-photon- and in coincidence mode (two Ge-68/Ga-68 rod sources of 40 MBq each), respectively, resulted in a value of 0.18. The comparison of the effective doses caused by single-photon transmission and by emission measurement (injection of 250 MBq of FDG) yields a ratio of 2.3*10(-3). CONCLUSION: The radiation exposure of the patient caused by the transmission measurement for 3D whole-body-PET can be neglected. In comparison with the coincidence-transmission using uncollimated line sources of low activity the radiation exposure is still reduced using single photon trans-mission with collimated point sources of high activity.