Stefan Hoegerle

18F-DOPA positron emission tomography for tumour detection in patients with medullary thyroid carcinoma and elevated calcitonin levels

Abstract. In spite of the availability of numerous procedures, diagnostic imaging of tumour manifestations in patients with medullary thyroid carcinoma and elevated calcitonin levels is often difficult. In the present study, the new procedure of fluorine-18 dihydroxyphenylalanine positron emission tomography (18F-DOPA PET) was compared with the established functional and morphological imaging methods. After evaluation of the normal distribution of 18F-DOPA, 11 patients with medullary thyroid carcinoma were examined using 18F-DOPA PET. Results of 18F-fluorodeoxyglucose (18F-FDG) PET, somatostatin receptor scintigraphy (SRS) and morphological tomographic imaging (CT/MRI) were available for all patients. All individual procedures were evaluated without reference to prior information. Data assessment for each patient was based on cooperation between experienced radiologists and specialists in nuclear medicine, who considered all the available findings (histological results, imaging, follow-up studies). This cooperation served as the gold standard against which the results of the individual procedures were evaluated. A total of 27 tumours were studied [three primary tumours (PT)/local recurrence (LR), 16 lymph node metastases (LNM) and eight organ metastases (OM)]. 18F-DOPA PET produced 17 true-positive findings (2 PT/LR, 14 LNM, 1 OM), 18F-FDG PET 12 (2 PT/LR, 7 LNM, 3 OM), SRS 14 (2 PT/LR, 8 LNM, 4 OM) and morphological imaging 22 (3 PT/LR, 11 LNM, 8 OM). The following sensitivities were calculated with respect to total tumour manifestations: 18F-DOPA PET 63%, 18F-FDG PET 44%, SRS 52%, morphological imaging 81%. Thus, the morphological imaging procedures produce the best overall sensitivity, but the specificity for PT/LR (55%) and LNM (57%) was low. With respect to lymph node staging, the best results were obtained with 18F-DOPA PET. 18F-DOPA PET is a new functional imaging procedure for medullary thyroid carcinoma that seems to provide better results than SRS and 18F-FDG PET. Moreover, the data indicate that no single procedure provides adequate diagnostic certainty. Therefore, 18F-DOPA PET is a useful supplement to morphological diagnostic imaging, improving lymph node staging and enabling a more specific diagnosis of primary tumour and local recurrence.

Reproducibility of PET brain mapping of cancer patients.

Twenty German cancer patients (56.9±12.7 years old) without brain metastasis underwent neurological PET. The acquired brain data were compared to the data of ten age and sex‐matched controls (53.6±15.7). Scores of Zungs Self‐rating Depression Scale (SDS) obtained from 15 out of the 20 patients suggested they might be mildly depressed. Scores of Taylors Manifest Anxiety Scale (MAS), used for additional psychological evaluation, were close to normal distribution.

Incidental appendix carcinoid : Value of somatostatin receptor imaging

PURPOSE Somatostatin receptor scintigraphy is used to diagnose carcinoid of the gastrointestinal tract. Its sensitivity ranges from approximately 75%-100%. Therefore, it was hypothesized that it can be used in the postsurgical follow-up to detect residual carcinoid, recurrence, and metastatic disease. RESULTS This article is concerned with the findings of somatostatin receptor imaging performed on a 12-year-old girl 8 weeks after appendectomy. Histologic examination showed an incidental appendix carcinoid. Somatostatin receptor scintigraphy performed for detection of lymph node metastatic spread of the carcinoid showed focal tracer accumulation at the former operative site; subsequently, a right hemicolectomy was performed. However, histologic examination of the surgical tissue showed no evidence for carcinoid. CONCLUSION It is concluded that there are some potential pitfalls for somatostatin receptor imaging at least soon after surgery. Therefore, it should not be used to aid in reoperation.

SDHD mutations in carotid body tumors and pheochromocytomas: paraganglioma syndrome type 1

&NA; The succinyldehydrogenase subunit D gene (SDHD gene) is a newly recognized susceptibility gene for adrenal pheochromocytoma, extra‐adrenal abdominal and thoracic paraganglioma, and skull basis and neck paraganglioma, known as the paraganglioma syndrome type 1 (PGL1). The SDHD gene is located on chromosome 11q22.3–2.3 and consists of 4 exons. The mutations are spread randomly over all exons and include single amino acid changes and truncations of the gene product by stop codons, deletions, insertions or splice site alterations. Inheritance follows an autosomal‐dominant pattern, but tumors occur only in descendents of fathers carrying the mutation which is consistent with maternal imprinting of the SDHD gene. Patients become symptomatic in the 2nd to 6th decade of life. Major tumor sites are the adrenal medulla and the carotid body. Malignancy is very rare. Treatment of PGL1 is a great challenge and requires abdominal, ENT and thoracic surgery, which should be performed in an atraumatic and whenever possible endoscopic and adrenal‐sparing fashion.

Staging an esophageal carcinoma by F-18 fluorodeoxyglucose whole-body positron emission tomography.

A 49-year-old man was evaluated for dysphagia. Double-contrast examination showed esophageal lumen narrowing, and histologic assessment of the endoscopically obtained biopsy specimen revealed esophageal carcinoma. To plan the therapy strategy and stage tumors, CT and F-18 fluorodeoxyglucose whole-body positron emission tomography (PET) were performed. Surprisingly, the PET scan revealed a bone metastasis in the spine (T3), which showed no morphologic correlate on the CT. To clarify this discrepancy, MRI was performed and confirmed a metastasis of the third thoracic vertebrae. Infiltration of the bone marrow occurred with malignant cells but without any morphologic changes of the osseous structure. This case indicates that PET may be important for tumor staging.