Uwe Cremerius

Fluorine-18 fluorodeoxyglucose positron emission tomography in thyroid cancer: results of a multicentre study

n=222) and the group with negative radioiodine scan (n=166), respectively. Specificity was 90% in the whole patient group. Sensitivity and specificity of WBS were 50% and 99%, respectively. When the results of FDG-PET and WBS were considered in combination, tumour tissue was missed in only 7%. Sensitivity and specificity of MIBI/Tl were 53% and 92%, respectively (n=117). We conclude that FDG-PET is a sensitive method in the follow-up of thyroid cancer which should be considered in all patients suffering from differentiated thyroid cancer with suspected recurrence and/or metastases, and particularly in those with elevated thyroglobulin values and negative WBS.

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.

Does positron emission tomography using 18-fluoro-2-deoxyglucose improve clinical staging of testicular cancer?— results of a study in 50 patients

OBJECTIVES To compare positron emission tomography (PET) using 18-fluoro-2-deoxyglucose (FDG) with conventional clinical staging in unselected patients with germ cell cancer. METHODS Fifty patients underwent PET scans of the abdomen (n = 50) and chest (n = 41 ) after the initial diagnosis. PET images were evaluated qualitatively and quantitatively using standardized uptake values (SUVs). The results were compared with computed tomography (CT) results and tumor markers (human chorionic gonadotropin, alpha-fetoprotein, and lactate dehydrogenase). Retroperitoneal lymphadenectomy in 12 patients and clinical staging, including follow-up data in all patients, were taken as a reference standard. RESULTS PET detected metastases in 13 (87%) of 15 patients and excluded metastases in 33 (94%) of 35 patients. A sensitivity of 73% and a specificity of 94% were obtained using CT. The respective values for tumor marker determination were 67% and 100%. Retroperitoneal metastases were detected in 2 patients by PET only and in 1 patient by CT only. In the latter patient, surgery of a residual mass after chemotherapy revealed a well-differentiated teratoma. False-negative findings with PET and CT occurred in 2 patients with retroperitoneal metastases approximately 10 mm in size. False-positive findings were due to sarcoidosis or to muscular activity of the neck. Quantitative FDG uptake was very heterogeneous, with an SUV ranging from 1.8 to 17.3. CONCLUSIONS FDG PET has the potential to improve clinical staging of testicular cancer. However, PET, as well as CT, is limited in the detection of small retroperitoneal lymph node metastases.

Benign versus malignant osseous lesions in the lumbar vertebrae : differentiation by means of bone SPET

Abstract.Bone scanning is a well-accepted and frequently performed diagnostic procedure with a high sensitivity, especially when single-photon emission tomography (SPET) acquisitions are added. However, the differentiation of benign from malignant osseous lesions often poses difficulty. The purpose of this study was to find out whether the particular localisation of an intraosseous lesion in a lumbar vertebra is an indicator of its aetiology. Bone scintigraphy including planar whole-body scans as well as SPET imaging of the lumbar spine was performed in 109 patients. The diagnoses of osseous lesions in the lumbar vertebrae were made strictly on the basis of the findings of magnetic resonance imaging, computed tomography or plain radiography. Sixteen patients had to be excluded from the study because they did not undergo adequate radiological examination. To determine the particular localisation of vertebral lesions in the bone scan, two experienced nuclear medicine physicians examined the studies independently while blinded to the radiological results. Four anatomical regions were differentiated within the vertebra: the vertebral body, the pedicle, the facet joints and the spinous process. Clopper-Pearson analysis, which takes into account the number of examinations, yielded the following probability intervals for the malignancy of intraosseous lesions in the lumbar spine: vertebral body 36.8%–57.3%, pedicle 87.7%– 100%, facet joints 0.8%–21.4% and spinous process 18.7%–81.3%. It was concluded that lesions affecting the pedicle are a strong indicator for malignancy, whereas involvement of the facet joints is usually related to benign disease. Lesions affecting the vertebral body or the spinous process do not show a clear tendency towards either malignancy or benignity. In contrast to other studies, a significant probability of malignancy (35.6%) was observed in lesions affecting exclusively the vertebral body.

Ergebnisse der Positronen- emissionstomographie mit Fluor-18-markierter Fluordesoxyglukose bei Differentialdiagnose und Staging des Pankreaskarzinoms

ZusammenfassungTrotz methodischer Verbesserungen in der Diagnostik des Pankreaskarzinoms ist die Differentialdiagnose pankreatischer Raumforderungen bei bestehender chronischer Pankreatitis sowie der Nachweis etwaiger Lymphknotenmetastasen bislang nur unvollständig gelöst. Die Bestimmung des regionalen Glukosestoffwechsels mit Hilfe der Positronenemissionstomographie (PET) und Fluor-18-markierter Fluordesoxyglukose (FDG) stellt einen neuen diagnostischen Ansatz dar, der nicht auf dem Nachweis morphologischer sondern metabolischer Tumorcharakteristika beruht. Bei 85 Patienten mit vermutetem Pankreaskarzinom wurde präoperativ eine FDG-PET durchgeführt und der Befund mit der histopathologischen Aufarbeitung des Operationspräparats verglichen. Von 55 malignen Tumoren konnten 47 anhand ihres Hypermetabolismus korrekt klassifiziert werden (85 %), 23 von 30 benignen Tumoren (77 %) wiesen keine Stoffwechselsteigerung auf (richtig-negativ). In der Ausbreitungsdiagnostik zeigte PET in 19 von 31 Fällen (61 %) korrekt das Vorliegen regionaler Lymphknotenmetastasen, in 7 von 13 Fällen (54 %) eine Lebermetastasierung an. Falsch negative Befunde fanden sch bei Diabetikern (5 von 8 unentdeckten Primärtumoren) während falsch positive Ergebnisse mehrheitlich (4 von 7) auf akut entzündliche Veränderungen bei chronischer Pankreatitis zurückzuführen waren. Diese Ergebnisse belegen, daß durch die FDG-PET eine Verbesserung der Diagnostik unklarer pankreatischer Raumforderungen erreicht werden kann, die zu einer Reduktion unnötiger Laparatomien beitragen könnte.SummaryAlthough the detection of pancreatic carcinoma has been considerably improved by recently developed imaging procedures, differential diagnosis between cancer and benign tumor masses, as well as lymph node staging, is still difficult. In vivo evaluation of regional glucose metabolism by means of positron emission tomography (PET) and fluorine-18-labelled fluorodeoxyglucose (FDG) is a new approach utilizing metabolic instead of morphological tumor properties for diagnosis.Patients and methods: A total of 85 patients with suspected pancreatic carcinoma were investigated by FDG-PET prior to surgery. Static PET scans were evaluated visually as well as quantitatively, taking increased FDG uptake as a sign of malignancy. PET results were correlated with intraoperative findings and histopathology of surgical specimens.Results: Forty-seven out of 55 (85 %) malignant tumors and 23 out of 30 (77 %) benign lesions were correctly classified by PET. Lymph node metastases were present in 31 patients, 19 of them (61 %) positive in PET. In 7 our of 13 (54 %) patients with liver metastases, PET detected hypermetabolic lesions. False-negative findings were mainly due to disturbance of glucose metabolism in diabetic patients, while most false-positive results could be attributed to acute inflammatory lesions in chronic pancreatitis.Conclusions: Our results indicate that classification of pancreatic masses can be improved by use of FDG-PET, which might lead to a reduction of unnecessary laparotomies in patients with benign or incurable disease.

Dual-head gamma camera 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography in oncological patients: effects of non-uniform attenuation correction on lesion detection

Abstract. The purpose of this study was to evaluate a dual head coincidence gamma camera (DH-PET) equipped with single-photon transmission for 2-[fluorine-18]-fluoro-2-deoxy-d-glucose (FDG) imaging in oncological patients. Forty-five patients with known or suspected malignancies, scheduled for a positron emission tomography (PET) scan, were first studied with a dedicated ring PET and subsequently with DH-PET. All patients underwent measured attenuation correction using germanium-68 rod sources for ring PET and caesium-137 sources for DH-PET. Ring PET emission scan was started 64±17 min after intravenous administration of 235±42 MBq FDG. DH-PET emission followed 160±32 min after i.v. FDG. Attenuation-corrected and non-attenuation-corrected images were reconstructed for ring PET and DH-PET. The image sets were evaluated independently by three observers blinded to clinical data and to results of conventional imaging. Attenuation-corrected ring PET as the standard of reference depicted 118 lesions, non-attenuation-corrected ring PET 113 (96%) lesions, and attenuation-corrected DH-PET and non-attenuation-corrected DH-PET, 101 (86%) and 84 (71%) lesions, respectively (P<0.05). The lesion detection rate of attenuation-corrected and non-attenuation-corrected DH-PET was almost similar for lesions >20 mm, whereas attenuation correction increased the detection rate from 60% to 80% for lesions ≤20 mm (P<0.01). A patient-based analysis revealed concordant results relative to attenuation-corrected ring PET for non-attenuation-corrected ring PET, attenuation-corrected DH-PET and non-attenuation-corrected DH-PET in 42 (93%), 36 (80%) and 31 (69%) patients, respectively. Differences might have influenced patient management in two (4%), six (13%) and ten (22%) patients, respectively. In conclusion, measured attenuation correction markedly improves the lesion detection capability of DH-PET. With measured attenuation correction the diagnostic performance of DH-PET is closer to that of dedicated ring PET.

Mediastinal staging of lung cancer with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography and a dual-head coincidence gamma camera.

Abstract. The aims of the present study were (a) to evaluate mediastinal staging in patients with lung cancer with 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) using a coincidence gamma camera (hybrid PET) in comparison with dedicated positron emission tomography (PET) and computed tomography (CT), and (b) to assess the feasibility to determine standardized uptake values (SUV) with hybrid PET. Forty patients were included in the study. Hybrid PET was performed without and with attenuation correction. Data were rebinned with single-slice (SSRB) or Fourier rebinning (FORE). The SUVs of primary tumors were calculated with hybrid PET and compared with SUVs determined by dedicated PET. Diagnostic accuracy for hybrid with or without attenuation correction was 80 or 74% compared with 82% for dedicated PET, and 63% for CT. Attenuation-corrected hybrid PET revealed a higher specificity than CT (83 vs 52%; p<0.05). The SUVs of primary tumors were similar to those of hybrid PET and dedicated PET with a mean relative difference of 20.8±16.4%. The FORE improved the agreement of SUVs with a mean relative difference of 13.8±9.9 vs 36.0±17.9% for SSRB (p<0.001). Hybrid PET with attenuation correction is more specific than CT for mediastinal staging in patients with lung cancer (p<0.05). It reveals similar results in comparison with dedicated PET. Calculation of SUVs with hybrid PET is feasible.

The present role of bone marrow scintigraphy

An experimental study in animals performed in 1973 by Ito et al. [1] showed that bone marrow scans applying radiocolloids reveal skeletal involvement by malignant tumours earlier than do planar X-rays and radionuclide bone scans. The authors stated that “radiocolloid marrow scanning appears to be one of the methods of choice in the early diagnosis of metastatic skeletal malignancies”. With the practical limitations of the method in mind, the authors called for “development of more excellent radiopharmaceuticals suitable for bone marrow imaging, improvement of resolution, and advance in the handling of scan data”. What happened to bone marrow scintigraphy (BMS) in the past 25 years regarding these three requirements demanded by Ito et al.? Radiocolloids initially used for imaging of the liver were adopted for BMS throughout the 1980s and also in the 1990s. Nanosized colloid proved to be superior to other colloids with regard to bone marrow/spleen and bone marrow/background ratios [2]. Immunoscintigraphy with a technetium-99m-labelled murine monoclonal IgG antibody against NCA-95 was introduced as a novel radiopharmaceutical with improved imaging characteristics in 1988 [3]. Use of this antibody, equally directed against granulopoietic bone marrow cells and granulocytes in the peripheral blood, resulted in a bone marrow uptake 2–4 times higher than that of microcolloid [4]. The image quality was clearly superior; uptake in overlying ribs and thoracic vertebrae was usually not significantly obscured by that of the liver and spleen [5]. 99mTclabelled monoclonal anti-NCA95 antibodies are now regarded as the radiopharmaceutical of choice for BMS [6]. A disadvantage of anti-NCA95 immuno-scintigraphy using complete IgG antibodies is the induction of human antimurine antibodies (HAMA) in approximately 5% of patients, resulting in altered biodistribution, increased hepatic uptake and non-diagnostic imaging in the case of repeated application [7]. 99mTc-labelled anti-NCA-90 immunoscintigraphy applying Fab’ fragments, now used for imaging of infection, is not suitable for bone marrow imaging, and a fragmented antibody which would combine high bone marrow uptake and low antigenicity is not yet available. Resolution of gamma cameras has not changed basically during the last two decades, although thinner crystals optimised for 99mTc as the leading radionuclide may have improved image quality slightly. The use of singlephoton emission tomography (SPET) has been shown to provide additional valuable information in bone imaging of the spine [8]. However, in BMS the use of SPET has not yet been exploited in larger studies, although optimal resolution and delineation of vertebral structures are as crucial as in bone scintigraphy. Sagittal reconstruction of the SPET data set may give the best overview of the spine and is easily comparable to magnetic resonance imaging (MRI) or fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) images. Volumeand surface-rendered images provide a 3D image of the functional bone marrow mass, and overlay techniques can be employed to fuse image data with those of MRI or FDG-PET.

18-FDG-PET der Leber zur Therapiekontrolle der palliativen regionalen Port-Chemotherapie

Die palliative regionale Portchemotherpay von Lebermetastasen stellt ein Therapieprinzip dar, dessen Einflus auf die Prognose der Patienten derzeit trotz zahlreicher Studien noch nicht abschliesend beurteilt werden kann. Unbestritten ist, das ein Anteil von 20–40% der Patienten von dieser Therapie profitiert und eine deutliche Verkleinerung der Metastasen erfahrt. Mit der Positronenemissionstomographie (18-FDGPET) steht ein Verfahren zur Verfugung, welches Anderungen im Stoffwechsel der Metastasen wahrend der Therapie nachweisen kann. Aufgrund der Darstellung und quantitativen Erfassung von Stoffwechselvorgangen, bei hoher Sensitivitat und Spezifitat, ist mit der 18-FDG-PET eine fruhzeitige Aussage uber den therapeutischen Effekt einer palliativen Chemotherapie moglich. Dies kann insbesondere bei Patienten mit initial negativen Tumormarkern zur Entscheidung uber eine Therapiefortsetzung bzw. Anderung beitragen.