Patient external dose rate after 177Lu-DOTATATE therapy: factors affecting its decrease and predictive value.

Rationale: Peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE (oxodotreotide) results in external radiation exposure from the patient. In the PREELU observational prospective study, we determined the equivalent dose rate at 1 m of the patient (EDR-1m) for a period following PRRT. The main objective was to predict which patients could be discharged from the hospital at approximately 3 h after the administration of 177Lu-DOTATATE, i.e. at the end of the infusion of amino-acids according to our PRRT protocol. As presenting no undue risk of radiation exposure for the public, those patients could be treated as outpatients or day patients, rather than inpatients. Methods: We sequentially measured EDR-1m facing the sternum and then the pelvis during 50 PRRT in 24 patients with metastatic neuroendocrine tumours, each 30 minutes after ending administration of Lutathera, over at least 180 minutes. Results: 180 minutes after the administration of ca. 7400 MBq of Lutathera, EDR-1m was <40 µSv/h in all cases, and <25 µSv/h in 32 cases (64%). After an overnight hospital stay, EDR-1m was <25 µSv/h in all cases. The EDR-1m value measured facing the sternum was the greatest in about one-fourth of paired measurements. In patients whose creatinine clearance was >96 mL/min/1.73m2, the EDR-1m was most likely (predictive value=90%) to drop below 25 µSv/h within 180 minutes after the administration of Lutathera. In 16 patients who benefited from several PRRT cycles, the creatinine clearance did not decrease significantly from one cycle to the next, probably due to the kidney protection by the amino-acid infusion. The patients whose EDR-1m dropped below 25 µSv/h at 180 minutes during their first PRRT cycle were unlikely (predictive value= 88%) to decease during the following two years. Conclusion: All patients could have been discharged 3 h after administration according to the criterion EDR-1m <40 µSv/h. Using EDR-1m <25 µSv/h as criterion, an extended hospital stay beyond 3 h would have been necessary in around one-third of the PRRT treatments and could be anticipated based on creatinine clearance ≤96 mL/min/1.73m2. EDR-1m <25 µSv/h at 180 min during the first PRRT yielded a strong predictive value on the patient's survival at two years, a finding that should be confirmed in future studies.

The intensity of 18FDG uptake does not predict tumor growth in patients with metastatic differentiated thyroid cancer.

PURPOSE: In patients with metastatic differentiated thyroid carcinoma (DTC), fluorodeoxyglucose (FDG) uptake as well as age, tumor size and radioactive iodine (RAI) uptake are prognostic factors for survival. High FDG uptake is a poor prognostic factor and lesions with high FDG uptake are often considered aggressive, but the predictive value of FDG uptake for morphological progression is unknown. The principal aim of this retrospective single center study was to determine whether the intensity of FDG uptake was correlated on a per lesion analysis with tumor growth rate (TGR) expressed as the percentage of increase in tumor size during 1 year (1-year TGR). METHODS: Fifty five patients with DTC were included between July 2012 and May 2014 with the following criteria: (i) at least one distant metastasis measuring ≥ 1 cm in diameter on CT scan (ii) evaluation by FDG-positron emission tomography/computed tomography (PET/CT) performed at our center (iii) at least one CT or another FDG-PET/CT performed 3 to 12 months after the reference FDG-PET/CT in the absence of systemic or local treatment between the two imaging procedures. RESULTS: One hundred and fifty-six metastatic lesions located in lungs (63), neck lymph nodes (28), chest lymph nodes (42), bone (11), liver (2) and other sites (12) were studied. The median size was 16 mm, median SUVmax/lesion: 8.7; median metabolic tumor volume/lesion (Metab.TV/lesion): 3.7 cm3. The median 1-year TGR was 40.68 %. SUVmax and Metab.TV/lesion were not correlated to their 1-year TGR (p = 0.38 and p = 0.74 respectively). Among single patients with multiple lesions, the lesions with the highest SUVmax/lesion or the highest Metab.TV/lesion did not disclose the higher 1-year TGR. CONCLUSION: The intensity of FDG uptake on a per lesion analysis is not correlated to its 1-year TGR and cannot be used as a surrogate marker of tumour progression.

Functional imaging for evaluation of cancers and biologically conformal radiotherapy: Past-history and present-day perspectives.

Over the past twenty years, nuclear medicine has enhanced the role of functional imaging in cancerology. A major milestone was achieved in the early 2000s with widespread availability of the positron emitter tracer 18F- deoxyglucose (FDG) and the introduction of hybrid imagers, i.e. positron imagers coupled with an X CT, providing anatomical landmarks and potently contributing to attenuation and scatter correction of the images. Other technical advances have progressively increased the quality of positron images. To date, the most widely used tracer remains FDG, which is highly beneficial in terms of sensitivity and specificity in detection of tumor sites, also providing biological information on tumors and early evaluation of treatment response for most cancers. Other highly specific tracers have been developed and are now routinely used for pheochromocytoma and paraganglioma, neuroendocrine tumors, and prostate cancer. Biological Radiotherapy has two aspects: Internal radiotherapy consisting in administration of a tumor-specific molecule radiolabeled with an isotope delivering an adequate radiation dose to the targeted tumor sites (on the model of thyroid cancer treated with radioiodine) and external radiotherapy designed to determine tumor volume, assess response and to dose radiation according to the tumor characteristics shown by functional imaging.

Analysis of morbidity and clinical implications of laparoscopic para-aortic lymphadenectomy in a continuous series of 98 patients with advanced-stage cervical cancer and negative PET-CT imaging in the para-aortic area.

BACKGROUND: Laparoscopic para-aortic lymphadenectomy (PAL) is being used increasingly to stage patients with locally advanced cervical cancer (LACC) and to define radiation field limits before chemoradiation therapy (CRT). This study aimed to define clinical implications, review complications, and determine whether surgical complications delayed the start of CRT. METHODS: We retrospectively reviewed a continuous series of patients with LACC, with no positive para-aortic (PA) nodes on positron emission tomography-computed tomography (PET-CT) and who had undergone a primary laparoscopic PAL. RESULTS: From November 2007 to June 2010, 98 patients with LACC underwent pretherapeutic PAL. Two patients did not undergo PAL: extensive carcinomatosis was discovered in one case and a technical problem arose in the other. No perioperative complications occurred. Seven patients had a lymphocyst requiring an imaging-guided (or laparoscopic) puncture. Eight patients (8.4%, which corresponds to the false-negative PET-CT rate) had metastatic disease within PA lymph nodes. In cases of suspicious pelvic nodes on PET-CT, the risk for PA nodal disease was greater (24.0% versus 2.9%). When patients with and without surgical morbidity were compared, the median delay to the start of treatment was not significantly different (15 days; range, 3-49 days versus 18 days; range, 3-42 days). CONCLUSIONS: The morbidity of laparoscopic PAL was limited and the completion of treatment was not delayed when complications occurred. Nevertheless, if PET-CT of the pelvic area is negative, the interest in staging PAL could be discussed because the risk for PA nodal disease is very low.

Role of FDG PET/CT and chest CT in the follow-up of lung lesions treated with radiofrequency ablation.

PURPOSE: To compare fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with computed tomography (PET/CT) and chest CT in the evaluation of the effectiveness of lung radiofrequency (RF) ablation. MATERIALS AND METHODS: Institutional review board approved the study, and all patients gave written informed consent. Thirty-four patients (22 men and 12 women; mean age, 64 years) planned to undergo lung RF ablation were prospectively included and underwent FDG PET/CT and chest CT before (pre-RF ablation PET) and 24 hours, 1 month, and 3 months after RF ablation. Persistent equivocal findings up to 3 months were followed up. RESULTS: Pre-RF ablation PET led to changes in the treatment strategy in nine patients (26%) by depicting unexpected metastases. Two patients without FDG uptake in lesions to be treated were excluded. Overall, 28 patients (46 lesions: five primary cancer, 41 metastases) were treated and followed up. Within 3 months after RF ablation, incomplete treatment was diagnosed in four of 28 patients (14%, three at 1 month and one at 3 months). Findings of FDG PET/CT were true-positive in four, false-positive in one, and true-negative in 23 patients. Findings of chest CT were true-positive in one, false-positive in one, false-negative in three, and true-negative in 23 patients. Inflammatory FDG uptake in mediastinal lymph nodes and at the needle path puncture site used for RF ablation was observed in 15%, 21%, and 15% of patients and in 19%, 11%, and 15% of patients at 24 hours, 1 month, and 3 months, respectively. CONCLUSION: FDG PET/CT can be used for the evaluation of the effectiveness of lung RF ablation. Inflammatory FDG uptake in mediastinal lymph nodes or at the needle path site used for RF ablation may occur.

18F-fluorodeoxyglucose positron emission tomography and computed tomography in anaplastic thyroid cancer.

PURPOSE: Our aim was to evaluate in anaplastic thyroid carcinoma (ATC) patients the value of 18F-FDG PET/CT compared with total body computed tomography (CT) using intravenous contrast material for initial staging, prognostic assessment, therapeutic monitoring and follow-up. METHODS: Twenty consecutive ATC patients underwent PET/CT for initial staging. PET/CT was performed again during follow-up. The gold standard was progression on imaging follow-up (CT or PET/CT) or confirmation with another imaging modality. RESULTS: A total of 265 lesions in 63 organs were depicted in 18 patients. Thirty-five per cent of involved organs were demonstrated only with PET/CT and one involved organ only with CT. In three patients, the extent of disease was significantly changed with PET/CT that demonstrated unknown metastases. Initial treatment modalities were modified by PET/CT findings in 25% of cases. The volume of FDG uptake (≥300 ml) and the intensity of FDG uptake (SUVmax≥18) were significant prognostic factors for survival. PET/CT permitted an earlier assessment of tumour response to treatment than CT in 4 of the 11 patients in whom both examinations were performed. After treatment with combined radiotherapy and chemotherapy, only the two patients with a negative control PET/CT had a confirmed complete remission at 14 and 38 months; all eight patients who had persistent FDG uptake during treatment had a clinical recurrence and died. CONCLUSION: FDG PET/CT appears to be the reference imaging modality for ATC at initial staging and seems promising in the early evaluation of treatment response and follow-up.

Prognostic factors influencing survival from metastatic (stage IV) gastroenteropancreatic well-differentiated endocrine carcinoma.

Survival of metastatic gastroenteropancreatic well-differentiated endocrine carcinoma (GEP WDEC) is not well characterized. We evaluated the long-term outcome and prognostic factors for survival in 118 patients with distant metastases from GEP WDEC. Inclusion criteria were 1) pathological review by a single pathologist according to the present WHO criteria, 2) absence of previous therapy apart from surgery, 3) complete morphological evaluation within 3 months including somatostatin receptor scintigraphy, and 4) follow-up at Gustave-Roussy Institute until death or study's end. Clinical, biological marker, and pathological parameters were analyzed in univariate and multivariate statistical models. Survival after the first complete imaging work-up of the metastatic disease was determined using Kaplan-Meier method. Overall, survival for 5 years after the diagnosis of metastatic disease was 54%. In multivariate analysis, age (hazard ratio (HR): 1.05, 95% confidence interval (CI): 1.01-1.08, P = 0.01), the number of liver metastases (HR: 3.4, 95% CI: 1.4-8.3, P = 0.01), tumor slope (HR: 1.1, 95% CI: 1.0-1.1, P = 0.001), and initial surgery (HR: 0.3, 95% CI: 0.1-0.8, P = 0.01) were predictive of survival. Five-year survival was 100%, 91% (95% CI, 51-98%), 62% (95% CI, 37-83%), and 9% (95% CI, 6-32%) when patients had 0, 1, 2, 3 or more poor prognostic features respectively. This study enables the stratification of metastatic GEP WDEC patients into distinct risk groups. These risk categories can be used to tailor therapeutic approaches and also to design and interpret clinical trials.

F-18-Dopa Positron Emission Tomography/Computed Tomography Is More Sensitive Than Whole-Body Magnetic Resonance Imaging for the Localization of Persistent/Recurrent Disease of Medullary Thyroid Cancer Patients.

Background: Elevated postoperative serum calcitonin (Ctn) level indicates persistent/recurrent disease in patients with medullary thyroid carcinoma (MTC). Its location is a challenge. The aim of our study was to compare the disease detection rates of F-18-Dopa (fluoro dihydroxyphenylalanine) positron emission tomography (PET)/computed tomography (CT), whole-body (WB) magnetic resonance imaging (MRI), F-18-FDG (fluorodeoxyglucose) PET/CT, WB CT scanning, neck ultrasonography, and bone scintigraphy in MTC patients with increased Ctn levels and unknown localization of the source. Methods: We compared the independent reading of each imaging procedure with a reference assessment for structural disease defined by pathology or concordance between two imagings or with subsequent follow-up. The detection rate of each imaging modality was determined in per patient, per organ, and per lesion analysis. Results: Thirty-six consecutive patients (21 females, mean age: 57 years, sporadic MTC in 26 cases, median serum Ctn level: 760 pg/mL; range: 21-10,121) were analyzed. The reference assessment localized disease in 24 (64%) patients with 74 lesions detected in the thyroid bed (8), in neck lymph nodes (15), mediastinal lymph nodes (6), lungs (1), liver (2), bones (3), and other site (1). At the patient level, the detection rates were 64% (CI 0.48-0.80) for F-18-Dopa PET/CT with early acquisitions, 40% (CI 0.24-0.56) for F-18-FDG PET/CT, 40% (CI 0.24-0.56) for WB MRI, and 48% (CI 0.31-0.66) for WB CT scan. Conclusions: In MTC patients with increased Ctn and no known distant metastases, F-18-Dopa PET/CT is more sensitive to detect structural disease than any other imaging modality, including WB MRI.

Prospective study of bone marrow infiltration in aggressive lymphoma by three independent methods: whole-body MRI, PET/CT and bone marrow biopsy.

PURPOSE: Initial lymphoma staging requires bone marrow assessment in aggressive lymphomas. Bone marrow lymphoma infiltration is routinely assessed by bone marrow biopsy (BMB), considered as the "gold standard". The aim of this study was to compare the performance of BMB, whole-body MRI and PET/CT for evaluation of BM infiltration. METHODS: Patients with newly diagnosed aggressive lymphoma were evaluated by BMB, MRI and PET/CT. Two radiologists, two nuclear medicine physicians and one pathologist independently assessed the results of the three modalities. Bone was considered as involved if BM was positive or if PET/CT or MRI was positive and if there was a resolution of the abnormal image shown on PET/CT or MRI halfway or at the end of therapy. RESULTS: Both MRI and PET/CT detected bone marrow lesions in the 9/43 patients, but two patients with multiple lesions had more lesions detected by PET/CT compared to MRI. Among these nine patients, two with an iliac crest lesion detected by both MRI and PET/CT had bone marrow involvement with large-cell lymphoma on histological examination. The other seven patients had focal MRI and PET/CT lesions in areas other than the iliac crest, where the blind BMB was done. The other patients had bone marrow without large-cell lymphoma involvement. In all cases, after lymphoma therapy bone marrow involvement regressed on histological examination, PET and MRI. CONCLUSION: These preliminary results suggest that non-invasive morphological procedures could be superior to BMB for bone marrow assessment in aggressive lymphomas. Ongoing study is underway to validate these results.

Staging of peritoneal carcinomatosis: enhanced CT vs. PET/CT.

PURPOSE: To assess and compare the performance of CT and 18F-FDG-PET/CT in the evaluation of peritoneal carcinomatosis (PC). METHOD AND MATERIALS: Thirty consecutive patients with PC and scheduled for a surgery underwent a CT of the abdomen and pelvis and a whole-body 18F-FDG PET/CT. The extent of PC was assessed precisely using the peritoneal cancer index combining the distribution of tumor throughout 11 abdominopelvic regions with a lesion size score. CT and PET/CT imaging results were compared in all patients with intraoperative findings using an interclass correlation test. RESULTS: The presence of PC was correctly determined on CT and PET/CT in 23/28 and 16/28 patients, respectively. The extent of PC was understaged with CT and PET/CT in 27 patients and overstaged with CT and PET/CT in 1 and 2 patients, respectively. The interclass correlation was 0.53 (moderate) between CT and surgery and 0.12 (low) between PET/CT and surgery. The interclass correlation was higher for mucinous tumor (0.63) than for non-mucinous (0.16) on CT imaging whereas no difference was found in PET/CT. CONCLUSION: The intraperitoneal assessment of the extent of carcinomatosis, necessary to assess prognosis and treatment planning, is not accurate enough with CT and PET/CT imaging.

Imaging medullary thyroid carcinoma with persistent elevated calcitonin levels.

PURPOSE: Because calcitonin level remains elevated after initial treatment in many medullary thyroid carcinoma (MTC) patients without evidence of disease in the usual imaging work-up, there is a need to define optimal imaging procedures. PATIENTS AND METHODS: Fifty-five consecutive elevated calcitonin level MTC patients were enrolled to undergo neck and abdomen ultrasonography (US); neck, chest, and abdomen spiral computed tomography (CT); liver and whole-body magnetic resonance imaging (MRI); bone scintigraphy; and 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/CT scan (PET). RESULTS: Fifty patients underwent neck US, CT, and PET, and neck recurrence was demonstrated in 56, 42, and 32%, respectively. Lung and mediastinum lymph node metastases in the 55 patients were demonstrated in 35 and 31% by CT and in 15 and 20% by PET. Liver imaging with MRI, CT, US, and PET in 41 patients showed liver in 49, 44, 41, and 27% patients, respectively. Bone metastases in 55 patients were demonstrated in 35% by PET, 40% by bone scintigraphy, and 40% by MRI; bone scintigraphy was complementary with MRI for axial lesions but superior for the detection of peripheral lesions. Ten patients had no imaged tumor site despite elevated calcitonin level (median 196 pg/ml; range 39-816). FDG uptake in neoplastic foci was higher in progressive patients but with a considerable overlap with stable ones. CONCLUSION: The most efficient imaging work-up for depicting MTC tumor sites would consist of a neck US, chest CT, liver MRI, bone scintigraphy, and axial skeleton MRI. FDG PET scan appeared to be less sensitive and of low prognostic value.

Is FDG-PET scan in patients with early stage Hodgkin lymphoma of any value in the implementation of the involved-node radiotherapy concept and dose painting?

BACKGROUND AND PURPOSE: To evaluate the input of FDG-PET data in the implementation of the involved-node radiotherapy concept and dose painting. MATERIALS AND METHODS: Patients with early-stage Hodgkin lymphoma treated with combined modality treatments. First, patients underwent a PET/CT before chemotherapy in the treatment position using a head and shoulder immobilization mask. Second, all patients had a CT simulation for treatment planning. The CT simulation was coregistered with the prechemotherapy CT and FDG-PET scan. All prechemotherapy volumes were superimposed on the CT simulation. The initially involved lymph node areas to be irradiated were delineated on the CT simulation scan. Chemotherapy-induced shrinkage rates of the tumor masses visible on CT scan and on FDG-PET were determined and compared. RESULTS: Before chemotherapy, FDG-PET-avid areas represented 25% of the total volume on CT. After chemotherapy, the influence of initial FDG-PET data on the delineation of involved-node radiotherapy fields was significant and was due to the fact that in 36% of the patients, FDG-PET helped pinpoint lymph nodes that were undetected on CT. After chemotherapy, the rates of tumor volume shrinkage on CT and FDG-PET were similar. This finding suggests similar chemosensitivity for FDG-PET-avid and non-avid areas. There was no correlation between initial FDG-PET-avid volumes and the clinical outcome. CONCLUSION: Prechemotherapy FDG-PET data are essential for correctly implementing the involved-node radiotherapy concept but seem to be of minimal value for applying the concept of dose painting.

F-18 fluorodeoxy-D-glucose positron emission tomography scan in the initial evaluation of patients with a primary melanoma thicker than 4 mm.

Metabolic imaging with F-18 fluorodeoxy-D-glucose positron emission tomography is one of the most sensitive and non-invasive techniques, and has proved useful in melanoma. We designed, in 2004, at the Institute Gustave Roussy, a prospective study to determine the value of F-18 fluorodeoxy-D-glucose positron emission tomography scanning in the detection of regional and/or distant metastasis in 25 new patients referred for the treatment of a primary melanoma thicker than 4 mm (tumor node metastases stage T4). The sentinel lymph node biopsy was proposed for all the patients without a palpable regional lymph node. Abnormal positron emission tomography scan findings were correlated to available histological data and to the course of the disease. The F-18 fluorodeoxy-D-glucose positron emission tomography scan identified 0/2 intact primary melanomas, 1/4 residual primary melanomas after limited excision, 0/6 lymph node basins with micrometastasis, 4/4 lymph node basins with enlarged palpable lymph nodes and 0 distant metastasis. The sensitivity and specificity of positron emission tomography scans for microscopic lymph node disease in basins were, respectively, 0 and 92%. A false-positive F-18 fluorodeoxy-D-glucose positron emission tomography result in a cervical basin led to a useless cervical lymph node dissection. In three patients, the positron emission tomography scan was positive in distant sites but none of these foci represented a true metastasis. In conclusion, it is not useful to include a positron emission tomography scan in the initial work-up of patients with primary melanoma, even in patients with thick primary melanomas (>4 mm). Sentinel lymph node biopsy remains the technique of choice for the most accurate initial staging.

Detection of liver metastases from endocrine tumors: a prospective comparison of somatostatin receptor scintigraphy, computed tomography, and magnetic resonance imaging.

PURPOSE: To compare the respective sensitivity of somatostatin receptor scintigraphy (SRS), computed tomography (CT), and magnetic resonance imaging (MRI) in the detection of liver metastases from well-differentiated gastroenteropancreatic endocrine tumor (WDGEP ET) patients. To define predictive factors for "high-sensitivity SRS." PATIENTS AND METHODS: Sixty-four patients with WDGEP ET underwent SRS with abdominal single-photon emission computed tomography (SPECT), spiral CT, and 1.5-T MRI within a 15-day interval, the order of which was randomized. Two readers analyzed images of each modality, blindly and independently. RESULTS: Hepatic metastases were present in 40 of the 64 patients and confirmed by pathology after liver biopsy or surgery in 32 and eight patients, respectively. SRS, CT, and MRI detected a total of 204, 325, and 394 metastases, respectively. The number of detected metastases was significantly higher with MRI than with CT (P = .02) and SRS (P < 10(-4)) and higher with CT than with SRS (P < 10(-4)). SRS was negative in seven patients with a positive CT and/or MRI. More lesions were detected in 10 patients by SPECT compared with static views. The median metastasis size was significantly correlated (P = .04) with the sensitivity of SRS. CONCLUSION: MRI seems to have an edge over CT and SRS for the detection of liver metastases from endocrine tumors. We recommend the systematic performance of liver MRI at WDGEP ET initial staging and before major therapeutic events. The low performance of SRS was mainly explained by the impact of the metastasis size on the detection capacity of SRS.

Correlation of early metastatic response by 123I-metaiodobenzylguanidine scintigraphy with overall response and event-free survival in stage IV neuroblastoma.

PURPOSE: Metaiodobenzylguanidine (MIBG), specifically taken up in cells of sympathetic origin, provides a highly sensitive and specific indicator for the detection of metastases in neuroblastoma. The aim of this study was to correlate early response to therapy by MIBG scan, using a semiquantitative scoring method, with the end induction response and event-free survival (EFS) rate in stage IV neuroblastoma. PATIENTS AND METHODS: Seventy-five children older than 1 year and with stage IV neuroblastoma had 123I-MIBG scans at diagnosis, after two and four cycles of induction therapy, and before autologous stem-cell transplantation. The scans were read by two independent observers (concordance > 95%) using a semiquantitative method. Absolute and relative (score divided by initial score) MIBG scores were then correlated with overall pretransplantation response, bone marrow response, and EFS. RESULTS: The pretransplantation response rate was 81%, and the 3-year EFS rate was 32%, similar to a concomitant group of 375 stage IV patients. The median relative MIBG scores after two, four, and six cycles were 0.5, 0.24, and 0.12, respectively. The probability of having a complete response or very good partial response before transplantation was significantly higher if the relative score after two cycles was < or = 0.5, or, if after four cycles, the relative score was < or = 0.24. Patients with a relative score of < or = 0.5 after two cycles or a score of < or = 0.24 after four cycles had an improved EFS rate (P =.053 and.045, respectively). CONCLUSION: Semiquantitative MIBG score early in therapy provides valuable prognostic information for overall response and EFS, which may be useful in tailoring treatment.

6-[F-18]fluoro-L-DOPA positron emission tomography in the imaging of Merkel cell carcinoma: preliminary report of three cases with 2-deoxy-2-[F-18]fluoro-D-glucose positron emission tomography or pentetreotide-(111In) SPECT data.

PURPOSE: Merkel cell carcinoma (MCC) is an uncommon and aggressive cutaneous neoplasm of neuroendocrine origin. Somatostatin receptor scintigraphy (SRS) and positron emission tomography (PET) using 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) have been proposed to stage MCC and to detect early recurrences. As 6-[F-18]fluoro-L-DOPA (FDOPA) is taken up by other neuroendocrine tumors, we speculated that FDOPA-PET could image MCC. PROCEDURE: FDOPA-PET was performed together with FDG-PET (three patients) and SRS (two patients) in different clinical settings: localization of the primary tumor, staging, and suspicion of recurrence. RESULTS: Uptake of FDOPA-(18F) by MCC was observed in the two true-positive cases, with an agreement between the results of FDOPA-PET, FDG-PET, and SRS; however, the contrast was lower on FDOPA-PET than on FDG-PET images. In the last patient suspected of recurrence repeatedly on SRS and with inconclusive FDG-PET, FDOPA-PET was negative, and a 12-month follow-up demonstrated a true-negative result. CONCLUSION: MCC takes up FDOPA-(18F). The potential role of FDOPA-PET in its management warrants clarification.

Preoperative localization of neck recurrences from thyroid cancer: charcoal tattooing under ultrasound guidance.

BACKGROUND: Reoperation for thyroid cancer recurrence is a surgical challenge in previously dissected necks, and there is a need for a reliable procedure for surgeon guidance. In this study, the usefulness of preoperative charcoal tattooing for surgical guidance was evaluated. METHODS: From July 2007 to May 2010, 53 patients (40 females; Mage=44 years, range 19-76 years) were prospectively included for preoperative localization of neck recurrences from differentiated (n=46) or medullary thyroid cancer (n=7). Preoperative cytological assessment was performed for at least one lesion in each patient. Ultrasound (US) imaging was performed with high-frequency probes (8-14 Mhz). Micronized peat charcoal (0.5-3 mL) was injected under US guidance using a 25 gauge needle, 0-15 days preoperatively. RESULTS: A total of 106 lesions were selected for charcoal tattooing. Of these, 101 had been tattooed, and 102 were removed (85 metastases, 17 benign on pathology). The tolerance of charcoal injection was good in all but three patients. A mean volume of 1 mL of charcoal was injected with a mean of two targets per patient. Charcoal labeling facilitated intraoperative detection in 56 "difficult" lesions (i.e., small size, dense fibrosis, anatomical pitfalls), and charcoal trace facilitated intraoperative guidance in 17 lesions. Feasibility and usefulness rates were 83% and 70.7% respectively. CONCLUSION: These findings suggest that charcoal tattooing under US guidance is an easy to implement, safe, and useful procedure for surgeon guidance in neck reoperation for thyroid cancer.