Value of tumour marker S-100B in melanoma patients: a comparison to 18F-FDG PET and clinical data.

AIM: The S-100B protein is commonly used in the immunohistochemical diagnosis of malignant melanoma and its metastases and has recently been introduced as a tumor marker in peripheral blood, whereas 18F-FDG PET is currently the most sensitive in-vivo imaging method for melanoma staging. Thus, the efficiency of serum S-100B and 18F-FDG PET in the detection of metastatic disease in melanoma patients are compared. METHODS: Serum S-100B was measured with a commercially available immunoradiometric assay. As part of primary tumour staging whole-body positron emission tomography (PET) with 18F labeled fluorodeoxy-D-glucose (18F-FDG) was performed in 67 patients suffering from cutaneous melanoma with a tumour thickness > 0.75 mm and a Clark-level III-V. Final diagnosis based on histology, morphologic imaging results and/or clinical follow-up after at least six months. RESULTS: No evidence of disease was seen in 43 of 67 patients (64.2%), 11 patients (16.4%) presented with lymph node metastases, 13 patients (19.4%) had one or more distant metastases. Alltogether, 18 of 67 patients showed S-100B values > 0.2 microgram/l, including two patients without metastatic disease, 3 of 11 patients with lymph node metastases, and the 13 patients with distant metastases. One patient showed false-positive FDG-uptake in the mediastinum, but presented with S-100B values off curve. CONCLUSION: Our data indicate that serum S-100B determination might be helpful in identifying melanoma patients with distant metastases. In comparison to 18F-FDG PET, the value of serum S-100B for lymph-node staging is limited.

Comparison of [18F]FDG-PET and L-3[123I]-iodo-alpha-methyl tyrosine (I-123 IMT)-SPECT in primary lung cancer.

OBJECTIVE: The aim of this study was to evaluate L-3[123I]-iodo-alpha-methyl tyrosine (IMT)-SPECT and FDG-PET in pulmonary lesions suspected to be lung cancer. METHODS: Whole body PET (measured transmission corrected emission scans) was performed 45 minutes after i.v. injection of 222-370 MBq (6-10 mCi) 18F-FDG on a Siemens PET scanner (ECAT EXACT 47) including 5-6 bed positions. 123I-IMT-SPECT (chest) was performed after injection of 370 MBq (10 mCi) with a dual head camera (Picker Prism 2000) and commercially available reconstruction algorithms. Ten patients (6 male and 4 female) with suspected lung cancer were investigated. The results were compared to histological findings after surgery or bronchoscopic biopsies and CT. RESULTS: 123I-IMT-SPECT and FDG-PET were able to detect all 9 cases of lung cancer (1-8 cm in diameter). One case was true negative. Both imaging methods were true positive with respect to mediastinal lymph node metastases in one patient. The tumor/background ratio was higher with PET (8.20 vs. 2.84). CONCLUSION: Despite the limited number of patients it may be concluded that IMT-SPECT as well as FDG-PET are suited to correctly diagnose lung cancer. Nevertheless, FDG-PET, if available, seems to be better suited because of the higher tumor/background ratio and better resolution.

FDG PET and immunoscintigraphy with 99mTc-labeled antibody fragments for detection of the recurrence of colorectal carcinoma.

UNLABELLED: The aim of this study was to compare FDG PET with a new monoclonal antibody-based imaging agent that comprises an anti-carcinoembryonic antigen (CEA) monoclonal antibody Fab' fragment directly labeled with 99mTc. METHODS: Twenty-eight patients who were previously treated for colorectal carcinoma and in whom recurrence was suspected were examined with FDG PET and immunoscintigraphy. The most common indications were an elevation of serum CEA (13 patients), suggestive lesions documented by CT (9 patients), sonography (4 patients), and severe constipation (2 patients). Planar imaging and SPECT were performed 4-6 h after intravenous injection of the new imaging agent. Whole-body PET was performed 45-60 min after intravenous injection of FDG. The findings were confirmed by conventional diagnostic modalities, surgery, and histology. RESULTS: Histology confirmed local tumor recurrence in 9 of 28 patients. Clinical follow-up or CT confirmed the presence of liver metastases in 9 patients and lymph node involvement, lung metastases, and bone metastases in 2 patients each. The new agent correctly detected 8 of 9 local recurrences, whereas FDG PET was able to detect all 9 cases and in 1 case was false-positive. Liver metastases were confirmed in 9 patients by FDG PET but in only 1 patient by the new agent. Two cases with lymph node metastases and 2 cases with lung metastases were correctly identified by FDG PET, but none were detected by the new agent. Finally, bone metastases were identified in 1 patient by FDG PET but not with the new agent, whereas bone marrow infiltration (n = 1) was diagnosed by both imaging modalities. CONCLUSION: These results indicate that FDG PET and 99mTc-labeled anti-CEA Fab' are suitable for the diagnosis of local recurrence of colorectal carcinoma but that FDG PET is clearly superior in the detection of distant metastases (liver, bone, and lung) and lymph node involvement.

Liver perfusion scintigraphy prior to and after transjugular intrahepatic portosystemic shunts (TIPS) in patients with portal hypertension.

PURPOSE: This investigation was performed to compare the hemodynamic results of the transjugular intrahepatic portosystemic shunt, a new interventional treatment for portal hypertension, with those observed after the established surgical shunt interventions. METHODS: We examined 22 patients with portal hypertension due to liver cirrhosis before and after elective TIPS by liver perfusion scintigraphy. The relative portal perfusion was determined before and after the shunt procedure. Additionally, we measured the portal pressure gradient (PPG: portal-central venous pressure, mmHg). RESULTS: Prior to TIPS, the relative portal perfusion was significantly reduced to 22 +/- 9.1%. After the intervention we calculated values of 23.1 +/- 10.7% in the TIPS-group (p = 0.67; not significant). In spite of unchanged portal perfusion, the portal pressure was significantly (p < 0.001) reduced from 25.6 +/- 5.3 to 14.8 +/- 4 mm Hg. CONCLUSION: These results suggest that the reduction of portal hypertension by TIPS is effective. The portal perfusion is maintained by TIPS suggesting that liver perfusion is preserved to a higher degree.

Use of fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography in assessing the process of tuberculous spondylitis.

Fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography can be used to quantify the pathologic increase in glucose metabolism of inflammatory processes. Preliminary studies indicate a high level of sensitivity and specificity in detecting and identifying chronic osteomyelitis. This case study shows that positron emission tomography can be used to assess the process of inflammatory activity in tuberculous spondylitis. This technology also has the advantage of higher spatial resolution compared with other nuclear medicine procedures. In addition, it can differentiate between bone and soft tissue infection and allows imaging in the presence of metal implants.

Myocardial uptake of technetium-99m-furifosmin (Q12) versus technetium-99m-sestamibi (MIBI).

AIM: This study was performed to compare the myocardial uptake of Tc-99m-furifosmin (Q12) versus Tc-99m-sestamibi (MIBI) in correlation to the whole-body uptake under resting conditions. METHODS: 21 patients with coronary artery disease and no rest ischemia were examined. A whole-body scan was performed 60 min. p.i. under resting conditions. A quantification of the uptake (whole-body, heart and right lung) was done by ROI technique. RESULTS: The heart-to-lung ratio of Q12 (1.56 +/- 0.191) was significantly lower as compared to MIBI (1.94 +/- 0.197; p < 0.01). In contrast, the heart-to-whole-body ratios (Q12 versus MIBI: 0.027 +/- 0.012 versus 0.026 +/- 0.004; p < 0.76) did not differ. The lung-to-whole-body ratio (Q12 versus MIBI: 0.018 +/- 0.009 versus 0.013 +/- 0.002; p < 0.17) were different, but did not reach significance. CONCLUSION: These data show that under resting conditions the total myocardial uptake of Q12 does not differ significantly from that of MIBI. However, the pulmonary uptake of Q12 is slightly higher, resulting in a significant lower heart-to-lung ratio. These findings imply a lower image quality of Q12 compared to MIBI.

[Imaging of secondary pulmonary changes in central bronchial carcinomas by F-18-FDG PET]. / Darstellung sekundärer pulmonaler Veränderungen bei zentralen Bronchialkarzinomen in der F-18-FDG-PET.

AIM: The presented study was performed in order to evaluate the potential interference of secondary pulmonary changes (dystelectasis, retention pneumonia) with bronchial carcinomas in F-18-FDG-PET. METHOD: A retrospective analysis of F-18-FDG-findings in 33 patients with bronchial carcinoma (staging) was performed. Seven out of fourteen patients with central tumor localisation had secondary pulmonary changes (thorax-x-ray, CT), which were classified as dystelectasis or atelectasis in five cases and as retention pneumonia in two cases. RESULTS: Whereas dystelectasis and atelectasis without clinical signs of infection showed only mild to moderate FDG-accumulation (SUV 1.0-2.5; mean: 1.74), an intense FDG-uptake in the two cases with retention pneumonia (SUV 8.4 and 5.5) was observed. Despite of the typical wedge-like shape of pneumonia, differentiation between bronchial carcinoma and pneumonia can be a problem. CONCLUSION: We suggest, that an antibiotic treatment in patients with known retention pneumonia should be performed prior to the PET-scan in order to reduce the interference of inflammatory changes.

Functional imaging of Hodgkin's disease with FDG-PET and gallium-67.

We report a case of Hodgkin's lymphoma (Stage I B) which was studied using Ga-67-scintigraphy as well as whole body FDG-PET. Ga-67-scintigraphy detected a slightly increased uptake in the paraaortic and pelvic lymph nodes. However, FDG-PET was able to localize a much larger number of affected foci with a high glucose utilization rate in the right and left paraaortal regions, in the middle of the epigastrium, in the right and left parailiacal regions and one focus in the left upper mediastinum. Our experiences give rise to the assumption that FDG-PET ist significantly superior to gallium scintigraphy in Hodgkin's disease. Whole body FDG-PET can result in an upstaging of the patient and has therefore a major impact on the therapeutic management.

[Combination therapy of endemic goiter with two different thyroxine/iodine combinations]. / Studie zur Kombinationstherapie der endemischen Struma mit zwei unterschiedlichen Thyroxin/Iodkombinationen.

AIM: Of this study was to investigate the extent of thyrotropin (TSH) suppression and volume reduction in combination therapy of endemic goitre. We compared an individually adapted dose of thyroxine with a fixed dose. METHODS: 105 patients of a multicenter study (randomised, single blinded, controlled) received daily a weight-adjusted LT4-dose in combination with 150 micrograms iodide (group A) or a fixed combination of 100 micrograms LT4 plus 100 micrograms iodide (group B), respectively. At the beginning and after 12 weeks TSH-levels and goitre volume were examined. RESULTS: Although the amount of thyrotropin suppression showed no differences in both groups, there were more patients in the weight-adjusted treatment group with completely suppressed thyrotropin serum concentrations (p < 0.05). Both groups showed a reduction of goitre volume of 24% CONCLUSION: A weight-adjusted LT4-dose of 1.4 micrograms/kg body weight often leads to subclinical hyperthyroidism. To obtain low TSH-levels without complete suppression LT4-doses of 1.0 microgram/kg body weight plus 150 micrograms iodide are probably sufficient.

[Toxicity and radiation dosage of 2-(18F)-2-desoxy-D-glucose in positron emission tomography]. / Toxizität und Strahlendosis von 2-[18F]-2-Desoxy-D-Glukose in der Positronenemissionstomographie.

2-[18F]-FDG, a non-physiological glucose analogue, is the most important positron-emission- tomography (PET) radiopharmaceutical. As an example we refer to the production of 2-[18F]-FDG at the research center in Karlsruhe. 2-[18F]-FDG is synthesized in a "no carrier added" process. It is delivered at a maximal filling volume of 10 ml from a 14.5 ml batch with a batch-to-batch yield fluctuation from 5075 to 50,750 MBq and a specific activity from 1 to 10 GBq/mumol. The residual remaining synthesis reagents like solvents or catalysts have no toxicological relevance. The applicated dose per patient is in a range from 185 to 370 MBq and 1000 times lower than the correlating concentrations of stable FDG which can be regarded harmless in animals. 2-[18F]-FDG does not interfere with normal glucose metabolism. It is taken up by cells and phosphorylated to 2-[18F]-FDG-6-phosphate. The following dephosphorylation step is slow and the labeled compound is retained over several hours within the cells. Non-metabolized 2-[18F]-FDG is excreted rapidly in the urine to an extent of about 16% after 60 min, and 50% after 135 min, respectively. Fluorine-18F decays by emission of 511 KeV gamma photons. The whole body effective dose is reported to be 21 to 27 microSv/MBq. In case of an intravenous injection of 370 MBq this leads to a total dose of 7.8 to 10 mSv. The critical organ is the bladder wall (radiation dose 120 to 170 microSv/MBq or 80 to 100 mrem/mCi). The risk of a radiation induced late malignoma at 10 mSv can be estimated to be 1:2000. The genetical risk as a consequence of FDG-PET diagnostics would be 1:100,000 to 2:100,000 for dominant, and 5 times higher for recessive mutations.

Comparison of 18FDG-PET with 131iodine and 99mTc-sestamibi scintigraphy in differentiated thyroid cancer.

18Fluorine-fluorodeoxyglucose (FDG) positron-emission tomography (PET) has emerged as a useful method in various fields of oncology. The aim of the present study was to evaluate the clinical significance of this technique in differentiated thyroid carcinoma and to compare the results with other imaging modalities, particularly with whole-body 131iodine scintigraphy (WBS) and hexakis (2-methoxyisobutylisonitrile) (99m)technetium (I) scintigraphy (MIBI). Whole-body PET imaging using FDG was performed in 54 patients. There were 39 patients with papillary tumors and 15 patients with follicular tumors (including 3 Hürthle-cell carcinomas). Primary tumor stage (pT) was pT1 in 5 cases, pT2 in 19 cases, pT3 in 2 cases, pT4 in 24 cases, and unknown in 4 cases, respectively. Finally, for each case an overall clinical evaluation was done including histology, cytology, thyroglobulin level, sonography, computed tomography, magnetic resonance imaging, and subsequent clinical course, to allow a comparison with functional imaging results. Compared with WBS, FDG-PET gave different results in the majority of cases with recurrence/metastases (11 FDG-true-positive/WBS-negative tumor sites and 8 WBS-true-positive/FDG-negative tumor sites). In 7 patients with recurrence/metastases, FDG-PET and WBS gave corresponding results (10 sites). In 28 patients, FDG-PET and WBS were normal (including 2 false-negative cases). MIBI was performed in 44 cases. FDG-PET was better correlated to MIBI (congruent positive results in 13 tumor sites) than to WBS. Compared with MIBI, FDG-PET was superior in 5 cases (including 3 patients with distant metastases). Two FDG-negative/MIBI-positive tumors were observed. Different tracer uptake mechanisms have to be considered regarding "nonspecific" tumor imaging with FDG-PET or MIBI. Nevertheless, since spatial resolution with respect to tomographic imaging is inferior with single photon emission computer tomography (SPECT) using MIBI, the observed higher sensitivity of PET might be due to the higher spatial resolution of this method. As far as grading could be obtained, FDG-PET seemed to be more sensitive than WBS in high-grade tumors, whereas WBS was positive predominantly in low-grade carcinomas, although statistical significance could not be reached. The results prove the clinical usefulness of FDG-PET and MIBI for detection of 131iodine-negative tumor tissue in differentiated thyroid cancer.

[PET scan in general practice for diagnosis of breast carcinoma]. / PET in der Praxis bei der Diagnostik des Mammakarzinoms.

The value of whole body positron emission tomography using 18F-fluoro-deoxy-glucose (18FDG) in primary work-up and follow-up was evaluated retrospectively in 104 patients with primary or metastatic breast cancer. Compared to other imaging methods, FDG-PET sensitivity was superior to sonography, CT or MRT. Another advantage is the possibility of whole body imaging and the earlier detection of lymph node metastasis due to the recognition of functional metabolic changes compared to structural changes found with conventional imaging methods.