Frédéric Daenen

Value of FDG-PET in detecting residual or recurrent nonsmall cell lung cancer

In order to evaluate the usefulness of 18-fluorodeoxyglucose (FDG) positron emission tomography (PET) in the assessment of therapeutic effects, a study was performed before and after therapy in 126 patients with non-small cell lung cancer (NSCLC) codified stage I to stage IIIB. Treatment with an early curative result was given in 58 patients, whereas in 68 cases it was limited to palliation. During the treatment follow-up period (8-40 months), each patient was evaluated every 3 months by clinical examination and < or =6 months by imaging techniques (PET and computed tomography (CT)). A diagnosis of persistent or recurrent tumour was established by means of pathological analysis in 31 patients and by clinical evolution and subsequent imaging progression in 29 other patients. PET showed increased FDG uptake in all cases (n = 60) of persistent or recurrent tumour, whereas CT was nonspecific in 17 cases. Conversely, there were five false positive cases via PET imaging and three via CT. In detecting residual or recurrent NSCLC, PET had a sensitivity of 100% and specificity of 92%, whereas CT had a sensitivity and specificity of 71% and 95% respectively. In conclusion, 18-fluorodeoxyglucose positron emission tomography correctly identified response to therapy in 96% (121 of 126) of patients. Positron emission tomography appears to be more accurate (p = 0.05) than conventional imaging in distinguishing persistent or recurrent tumour from fibrotic scar in patients undergoing treatment for non-small cell lung cancer.

Whole-body positron emission tomography using fluorodeoxyglucose in patients with metastases of unknown primary tumours (CUP syndrome).

The aim of this study was to evaluate the clinical performances of whole body 2-[18F]fluorodeoxyglucose positron emission tomography (FDG PET) imaging for the detection of the primary tumour in patients with metastases of unknown origin. Forty-one patients, without previous history of known cancer (18 women and 23 men; average age 64.1 years) with metastasis confirmed by histopathological analysis were included in a retrospective study. Results of PET were compared with those of techniques used in the current conventional diagnostic procedure. All known metastatic lesions were detected by PET. There were 26 true-positive and two false-negative results. Primary tumour remained undetermined in eight patients after conventional investigations and PET. PET was superior to conventional diagnostic procedure in 11 patients and led to modify treatment in 11 patients. Sensitivity of PET was superior than computed tomography in detecting abdominal primary tumours. FDG PET is useful in patients with unknown primary tumour because its sensitivity is good and it could modify the disease management. Otherwise, PET allows the evaluation of the extent of the disease and could be used to monitor treatment efficiency. Its contribution has to be evaluated particularly in patients with primary tumour with a specific treatment.

Gamma-Probe-Directed Lymphatic Mapping and Sentinel Lymphadenectomy in Primary Cutaneous Melanoma

Background: Radiotracer and blue-dye lymphatic mapping is a recommended combined method to guide sentinel lymphadenectomy and full regional lymph node dissection in selected patients with cutaneous melanoma. Objective: To evaluate the diagnostic accuracy and the prognostic value of gamma-probe-directed lymphatic mapping in cutaneous melanomas. Methods: Sixty-five stage I and II melanoma patients underwent gamma-probe-directed lymphatic mapping. Sentinel lymph nodes were studied by both conventional and immunohistochemical stainings. The median follow-up was 11 months. Results: Sensitivities of preoperative and intraoperative sentinel lymph node detection were 100 and 98%, respectively. Only 1 failure of detection and 1 missed same-basin metastasis were experienced in the axillary and cervical areas, respectively. Eleven patients (16.9%) had sentinel node metastases leading to adjuvant therapy. Conclusion: Gamma-probe-directed lymphatic mapping is useful for staging melanoma. However, in the expectation of a more specific identification of the sentinel lymph node, the standard protocol remains recommended for exploring the axillary and cervical areas. The histological examination supported in some cases by immunohistochemistry remains mandatory in all cases.

Intérêt de la tomographie à émission de positrons dans l’évaluation des tumeurs gastro-intestinales

RésuméLa TEP au 18FDG présente de nombreuses indications dans l’évaluation des tumeurs digestives. Son rôle principal concerne le bilan d’extension des récidives tumorales démontrées ou suspectées mais des indications plus ponctuelles concernent également le diagnostic différentiel des masses pancréatiques et le bilan initial du cancer de l’œsophage. Le principal avantage de la TEP résulte de la nature métabolique du signal, indépendant et complémentaire des modifications anatomiques visibles en imagerie classique. Un autre avantage est lié à l’examen du corps entier aujourd’hui pratiqué systématiquement. La TEP trouve dès lors sa place en première ligne dans ses différentes indications.SummaryPET with 18-FDG has numerous indications in the evaluation of patients with gastrointestinal carcinoma. Its principal indications are the staging of suspected or demonstrated recurrent disease and to assess the operability of lesion. Validated indications also concern the differential diagnosis of pancreatic masses and the initial staging of oesophageal cancer.The metabolic signal of PET constitutes its main advantage. It is independent but complementary to the anatomical changes assessed by structural imaging. Another advantage is related to imaging of the whole-body is now routinely performed. PET can thus be a one step examination in the staging of digestive cancers and is best used early in the staging process.