Added value of 18F-florbetaben amyloid PET in the diagnostic workup of most complex patients with dementia in France: A naturalistic study.

INTRODUCTION: Although some studies have previously addressed the clinical impact of amyloid positron emission tomography (PET), none has specifically addressed its selective and hierarchical implementation in relation to cerebrospinal fluid analysis in a naturalistic setting. METHODS: This multicenter study was performed at French tertiary memory clinics in patients presenting with most complex clinical situations (i.e., early-onset, atypical clinical profiles, suspected mixed etiological conditions, unexpected rate of progression), for whom cerebrospinal fluid analysis was indicated but either not feasible or considered as noncontributory (ClinicalTrials.gov: NCT02681172). RESULTS: Two hundred five patients were enrolled with evaluable florbetaben PET scans; 64.4% of scans were amyloid positive. PET results led to changed diagnosis and improved confidence in 66.8% and 81.5% of patients, respectively, and altered management in 80.0% of cases. DISCUSSION: High-level improvement of diagnostic certainty and management is provided by selective and hierarchical implementation of florbetaben PET into current standard practices for the most complex dementia cases.

Quantitative analysis of normal and pathologic adrenal glands with 18F-FDOPA PET/CT: focus on pheochromocytomas.

INTRODUCTION: Many studies have reported the high performance of 6-fluorine-18-fluorodihydroxyphenilalanine (F-FDOPA) PET/CT in the diagnosis of pheochromocytomas but nobody seems to have investigated physiological and pathological adrenal glands from a quantitative point of view. The purpose of the present study was to assess the quantitative F-FDOPA uptake of normal and pathologic adrenal glands and to establish thresholds to characterize pheochromocytomas. We were especially interested in characterizing the remaining adrenal glands captation after an adrenalectomy. PATIENTS AND METHODS: We reviewed 112 F-FDOPA PET/CT scans taken for different indications. A total of 212 adrenal glands, of which 17 were pheochromocytomas, were analyzed on the basis of their functional and morphological features. The final diagnosis was based on histologic proof when available (six pheochromocytomas) or after synthesis of clinical, biological, morphological, and functional results. Maximum standardized uptake value (SUVmax), mediastinum, and liver ratios in case of pheochromocytomas, adenomas, and solitary adrenal glands were determined and compared with those of healthy glands. Receiver operating characteristic curves were determined and areas under the curve were compared for different cutoffs of each index. RESULTS: Pheochromocytomas demonstrated a higher F-FDOPA uptake compared with normal adrenal glands (mean SUVmax: 7.5, SD 4.0, range: 3.5-20.0 vs. mean SUVmax: 2.6, SD: 0.8, range: 1.0-6.9) (P<0.0001). An SUVmax threshold of 4.2 has a sensitivity and specificity of 94 and 98%, respectively. The areas under the curve were 0.988, 0.991, and 0.987 for an SUVmax of 4.2, a mediastinum ratio of 3.0, and a liver ratio of 1.7, respectively. A large number of nonsecreting pheochromocytomas were noticed. On the basis of the SUVmax no statistically significant difference was found between secreting (SUVmax: 8.9, SD: 5.3) and nonsecreting pheochromocytomas (SUVmax: 5.1, SD: 0.9) (P=0.141). After unilateral adrenalectomy, solitary glands presented no increased uptake compared with healthy adrenal glands. An unexpected lower captation was also observed (SUVmax: 2.0, P=0.047). CONCLUSION: We confirm the high affinity of F-FDOPA for secreting or nonsecreting pheochromocytoma. Indeed within a series of various adrenal glands, only these tumors presented a significant increased uptake compared with normal adrenal glands. Because of a high rate of nonhypersecreting lesions, F-FDOPA can act as a surrogate to biological assays. After an adrenalectomy, the remaining glands did not demonstrate compensatory accumulation of F-FDOPA. To our knowledge this last point has never been addressed.

Performance of 18F-FDG PET/CT in the Characterization of Adrenal Masses in Noncancer Patients: A Prospective Study.

Context: Few prospective studies have evaluated the role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the characterization of adrenal masses. Objective: To assess the performance of 18F-FDG PET/CT in the malignancy diagnosis of adrenal masses in noncancer patients. Design: Prospective multicenter study. Material and Methods: The study population consisted of 87 patients (87 adrenal masses) referred to endocrine surgeons: 56 with mass diameter ≥40 mm and 31 with a diameter <40 mm and of indeterminate nature based on unenhanced and washout CT attenuation densities. Fourteen patients had hypercortisolism. Adrenal masses were characterized by 18F-FDG PET/CT. Histology was the gold standard for the diagnosis of malignancy. In the absence of pathological proof (n = 23), the nature of the lesion was based on the 12-month imaging follow-up. Results: Fifteen adrenal masses were classified as malignant (including 11 adrenocortical carcinomas) and 72 as benign. Compared with benign lesions, malignant lesions were larger in size (P = 0.003), had higher unenhanced densities (P = 0.002), lower relative washout values (P = 0.007), and higher 18F-FDG uptake parameters (P < 10-3). The optimal threshold value of (Tumor SUVmax:Liver SUVmax) the ratio for malignancy was >1.5 with sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 86.7%, 86.1%, 56.5%, 96.9%, and 86.2%, respectively. Conclusions: Our results show that 18F-FDG PET/CT complements adrenal washout CT in the evaluation of adrenal masses and should be recommended in the evaluation of large and/or indeterminate adrenal masses.

Phase II Study of a Radiotherapy Total Dose Increase in Hypoxic Lesions Identified by 18F-Misonidazole PET/CT in Patients with Non-Small Cell Lung Carcinoma (RTEP5 Study).

See an invited perspective on this article on page 1043.This multicenter phase II study investigated a selective radiotherapy dose increase to tumor areas with significant 18F-misonidazole (18F-FMISO) uptake in patients with non-small cell lung carcinoma (NSCLC). Methods: Eligible patients had locally advanced NSCLC and no contraindication to concomitant chemoradiotherapy. The 18F-FMISO uptake on PET/CT was assessed by trained experts. If there was no uptake, 66 Gy were delivered. In 18F-FMISO-positive patients, the contours of the hypoxic area were transferred to the radiation oncologist. It was necessary for the radiotherapy dose to be as high as possible while fulfilling dose-limiting constraints for the spinal cord and lungs. The primary endpoint was tumor response (complete response plus partial response) at 3 mo. The secondary endpoints were toxicity, disease-free survival (DFS), and overall survival at 1 y. The target sample size was set to demonstrate a response rate of 40% or more (bilateral α = 0.05, power 1-ß = 0.95). Results: Seventy-nine patients were preincluded, 54 were included, and 34 were 18F-FMISO-positive, 24 of whom received escalated doses of up to 86 Gy. The response rate at 3 mo was 31 of 54 (57%; 95% confidence interval [CI], 43%-71%) using RECIST 1.1 (17/34 responders in the 18F-FMISO-positive group). DFS and overall survival at 1 y were 0.86 (95% CI, 0.77-0.96) and 0.63 (95% CI, 0.49-0.74), respectively. DFS was longer in the 18F-FMISO-negative patients (P = 0.004). The radiotherapy dose was not associated with DFS when adjusting for the 18F-FMISO status. One toxic death (66 Gy) and 1 case of grade 4 pneumonitis (>66 Gy) were reported. Conclusion: Our approach results in a response rate of 40% or more, with acceptable toxicity. 18F-FMISO uptake in NSCLC patients is strongly associated with poor prognosis features that could not be reversed by radiotherapy doses up to 86 Gy.

FDOPA Patterns in Adrenal Glands: A Pictorial Essay.

F-FDOPA is a well-established tool to explore pheochromocytomas. It tends to replace I-MIBG scan in metastatic pheochromocytomas, multiple endocrine neoplasia type 2-related tumors, succinate dehydrogenase [ubiquinone] iron-sulfur subunit-negative tumors, and succinate dehydrogenase[ZERO WIDTH SPACE]-positive lesions. To our knowledge, no study has characterized physiological and pathological adrenal glands with F-FDOPA from a quantitative point of view. We report the features of different normal and pathological adrenal glands with F-FDOPA. Within our series, only pheochromocytomas present a significantly increased uptake reflecting the high specificity of this tracer. Tumors such as adenomas or myelolipomas present no F-FDOPA significant accumulation. Interestingly, adrenal gland hyperplasia and solitary glands do not demonstrate compensatory uptake.

Interest of systematic screening of pheochromocytoma in patients with neurofibromatosis type 1.

OBJECTIVE: Pheochromocytoma (PHEO) may occur in 0.1-5.7% of patients presenting with a neurofibromatosis type 1 (NF1). Current recommendations are to explore only symptomatic patients. The objective of the study is to evaluate the prevalence and the interest of a systematic PHEO screening in this population. DESIGN: A prospective study in a French tertiary center including consecutive NF1 patients older than 18 years. METHODS: A systematic screening combining abdominal imaging and urinary fractionated metanephrines was proposed. In case of positivity of one or both exams, (123)I-metaiodobenzylguanidine scintigraphy or [(18)F]-fluoro-dihydroxyphenylalanine PET imaging was performed. The diagnosis of secreting PHEO was retained in case of elevated urinary metanephrines associated with positive scintigraphy and non-secreting PHEO when urinary metanephrines were normal with a positive scintigraphy. RESULTS: Between January 2014 and August 2015, 234 patients were included and 156 patients (66.7%) completed both exams. In these 156 patients, 12 PHEOs were diagnosed, representing a prevalence of 7.7%. Of these, six PHEOs were secreting, with only two symptomatic patients. The tumor size of these PHEOs were bigger than that of non-secreting PHEO (25.2 ± 6.6 vs 14 ± 6.9 mm, P = 0.0165). One lesion was bilateral. Mean metanephrine and normetanephrine levels were 3.2 ± 2.6N and 2.8 ± 1N respectively. Three patients underwent surgery. The six patients with non-secreting PHEO were asymptomatic. One of them had bilateral lesion and one underwent surgery. CONCLUSIONS: PHEO in NF1, whether or not secreting, are mostly asymptomatic. The current strategy to explore only symptomatic patients leads to an underestimation of prevalence with the risks inherent to the existence of an unrecognized PHEO.

FDG PET during radiochemotherapy is predictive of outcome at 1 year in non-small-cell lung cancer patients: a prospective multicentre study (RTEP2).

PURPOSE: To assess prospectively the prognostic value of FDG PET/CT during curative-intent radiotherapy (RT) with or without concomitant chemotherapy in patients with non-small-cell lung cancer (NSCLC). METHODS: Patients with histological proof of invasive localized NSCLC and evaluable tumour, and who were candidates for curative-intent radiochemotherapy (RCT) or RT were preincluded after providing written informed consent. Definitive inclusion was conditional upon significant FDG uptake before RT (PET1). All included patients had a FDG PET/CT scan during RT (PET2, mean dose 43 Gy) and were evaluated by FDG PET/CT at 3 months and 1 year after RT. The main endpoint was death (from whatever cause) or tumour progression at 1 year. RESULTS: Of 77 patients preincluded, 52 were evaluable. Among the evaluable patients, 77% received RT with induction chemotherapy and 73% RT with concomitant chemotherapy. At 1 year, 40 patients (77 %) had died or had tumour progression. No statistically significant association was found between stage (IIIB vs. other), histology (squamous cell carcinoma vs. other), induction or concomitant chemotherapy, and death/tumour progression at 1 year. The SUVmax in the PET2 scan was the single variable predictive of death or tumour progression at 1 year (odds ratio 1.97, 95% CI 1.25 - 3.09, p = 0.003) in multivariate analysis. The area under the receiver operating characteristic curve was 0.85 (95% CI 0.73 - 0.94, p < 10(-4)). A SUVmax value of 5.3 in the PET2 scan yielded a sensitivity of 70% and a specificity of 92% for predicting tumour progression or death at 1 year. CONCLUSION: This prospective multicentre study demonstrated the prognostic value in terms of disease-free survival of SUVmax assessed during the 5th week of curative-intent RT or RCT in NSCLC patients (NCT01261598; RTEP2 study).

Interobserver agreement of qualitative analysis and tumor delineation of 18F-fluoromisonidazole and 3'-deoxy-3'-18F-fluorothymidine PET images in lung cancer.

UNLABELLED: As the preparation phase of a multicenter clinical trial using (18)F-fluoro-2-deoxy-d-glucose ((18)F-FDG), (18)F-fluoromisonidazole ((18)F-FMISO), and 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) in non-small cell lung cancer (NSCLC) patients, we investigated whether 18 nuclear medicine centers would score tracer uptake intensity similarly and define hypoxic and proliferative volumes for 1 patient and we compared different segmentation methods. METHODS: Ten (18)F-FDG, ten (18)F-FMISO, and ten (18)F-FLT PET/CT examinations were performed before and during curative-intent radiotherapy in 5 patients with NSCLC. The gold standards for uptake intensity and volume delineation were defined by experts. The between-center agreement (18 nuclear medicine departments connected with a dedicated network, SFMN-net [French Society of Nuclear Medicine]) in the scoring of uptake intensity (5-level scale, then divided into 2 levels: 0, normal; 1, abnormal) was quantified by κ-coefficients (κ). The volumes defined by different physicians were compared by overlap and κ. The uptake areas were delineated with 22 different methods of segmentation, based on fixed or adaptive thresholds of standardized uptake value (SUV). RESULTS: For uptake intensity, the κ values between centers were, respectively, 0.59 for (18)F-FDG, 0.43 for (18)F-FMISO, and 0.44 for (18)F-FLT using the 5-level scale; the values were 0.81 for (18)F-FDG and 0.77 for both (18)F-FMISO and (18)F-FLT using the 2-level scale. The mean overlap and mean κ between observers were 0.13 and 0.19, respectively, for (18)F-FMISO and 0.2 and 0.3, respectively, for (18)F-FLT. The segmentation methods yielded significantly different volumes for (18)F-FMISO and (18)F-FLT (P < 0.001). In comparison with physicians, the best method found was 1.5 × maximum SUV (SUVmax) of the aorta for (18)F-FMISO and 1.3 × SUVmax of the muscle for (18)F-FLT. The methods using the SUV of 1.4 and the method using 1.5 × the SUVmax of the aorta could be used for (18)F-FMISO and (18)F-FLT. Moreover, for (18)F-FLT, 2 other methods (adaptive threshold based on 1.5 or 1.6 × muscle SUVmax) could be used. CONCLUSION: The reproducibility of the visual analyses of (18)F-FMISO and (18)F-FLT PET/CT images was demonstrated using a 2-level scale across 18 centers, but the interobserver agreement was low for the (18)F-FMISO and (18)F-FLT volume measurements. Our data support the use of a fixed threshold (1.4) or an adaptive threshold using the aorta background to delineate the volume of increased (18)F-FMISO or (18)F-FLT uptake. With respect to the low tumor-on-background ratio of these tracers, we suggest the use of a fixed threshold (1.4).

The predictive value of treatment response using FDG PET performed on day 21 of chemoradiotherapy in patients with oesophageal squamous cell carcinoma. A prospective, multicentre study (RTEP3).

PURPOSE: FDG PET has been suggested to have predictive value in the prognosis of oesophageal carcinoma. However, the retrospective studies reported in the literature have shown discordant results. Additionally, only four studies have evaluated FDG PET during chemoradiotherapy (CRT) in patients with different histological lesions. The purpose of this study was to investigate the predictive value of FDG PET performed early during CRT (on day 21) in a population of patients with oesophageal squamous cell carcinoma. METHODS: Included in this prospective study were 57 patients with a histological diagnosis of squamous cell carcinoma of the oesophagus. Of these 57 patients, 48 (84%) were evaluated (aged 63 ± 11 years; 44 men, 4 women). Each patient underwent FDG PET (4.5 MBq/kg) before CRT, according to the Herskovic protocol (t0; PET1) and on day 21 ± 3 from the start of CRT (d21; PET2). The response assessment included a clinical examination, CT scan or FDG PET and histological analysis 3 months and 1 year after PET1. The patients were classified as showing a complete response (CR) or a noncomplete response. A quantitative analysis was carried out for PET1 and PET2 using the following parameters: SUVmax, SUVmean (with SUVmean40 as the 3-D volume at an SUVmax threshold of 40% and SUVmeanp as that defined by a physician), tumour volume (TV, with TV40 defined as the TV at 40% of SUVmax, and TVp as that defined by a physician); and the total lesion glycolysis (TLG, SUVmean × TV, with TLG40 defined as the TLG at 40% of SUVmax, and TLGp as that defined by a physician). The differences in responses at 3 months and 1 year between PET1 (t0) and PET2 (d21) were assessed in terms of variations in SUV, TV and TLG using a repeated measures of variance (ANOVA). RESULTS: SUVmax, SUVmean and TLG decreased significantly between PET1 (t0) and PET2 (d21; p < 0.0001). The TV significantly decreased only when assessed as TVp (p = 0.02); TV40 did not decrease significantly. With respect to the predictive value of PET1, only TV40_1 and TVp_1 values, and therefore TLG40_1 and TLGp_1, but not the SUV values, were significantly lower in patients with CR at 3 months. SUVmax1, TVp_1 and TLGp_1 were significantly lower in patients with CR at 1 year. With respect to the predictive value of PET2, only TV40_2 and TVp_2 values, and therefore TLG40_2 and TLGp_2, but not the SUV values, were significantly lower in patients with CR at 3 months. None of the PET2 parameters had significant value in predicting patient outcome at 1 year. The changes in SUVmax, TV40, TVp, TLG40 and TLGp between PET1 and PET2 had no relationship to patient outcome at 3 months or 1 year. CONCLUSION: This prospective, multicentre study performed in a selected population of patients with oesophageal squamous cell cancer demonstrates that the parameters derived from baseline PET1 are good predictors of response to CRT. Specifically, a high TV and TLG are associated with a poor response to CRT at 3 months and 1 year, and a high SUVmax is associated with a poor response to CRT at 1 year. FDG PET performed during CRT on day 21 appears to have less clinical relevance. However, patients with a large functional TV on day 21 of CRT have a poor clinical outcome (ClinicalTrials.gov NCT 00934505).

Imaging work-up for screening of paraganglioma and pheochromocytoma in SDHx mutation carriers: a multicenter prospective study from the PGL.EVA Investigators.

CONTEXT: Recommendations have not been established concerning imaging to screen SDHx mutation carriers for paraganglioma and pheochromocytoma. OBJECTIVE: Our objective was to compare the performance of gadolinium-enhanced magnetic resonance angiography, contrast-enhanced computed tomography, and [(123)I]metaiodo-benzylguanidine and somatostatin receptor scintigraphies for detecting head and neck and thoracic-abdominal-pelvic paragangliomas in SDHx mutation carriers. DESIGN AND SETTING: We conducted a prospective, multicenter study from June 2005 to December 2009 at 23 French medical centers. PATIENTS: A total of 238 index cases or relatives carrying mutations in SDHD, SDHB, or SDHC genes were included. INTERVENTION: Images obtained by each technique were analyzed blind, without knowledge of results from other tests, first in each local center and then centrally. MAIN OUTCOME MEASURES: We evaluated sensitivity, specificity, and likelihood ratios for individual and combinations of tests, the gold standard being the consensus of an expert committee. RESULTS: Two hundred two tumors were diagnosed in 96 subjects. At local assessment, the sensitivity of anatomical imaging for detecting all tumors was higher (85.7%) than that of both scintigraphic techniques (42.7% for [(123)I]metaiodo-benzylguanidine and 69.5% for somatostatin receptor scintigraphy), except for thoracic localizations where somatostatin receptor scintigraphy was more sensitive (61.5 vs. 46.2% for anatomical imaging and 30.8% for [(123)I]metaiodo-benzylguanidine scintigraphy). The best diagnostic performance during local assessment was obtained by combining anatomical imaging tests and somatostatin receptor scintigraphy (sensitivity 91.7%). Central assessment significantly increased the sensitivity (98.6%) of tests in combination. CONCLUSIONS: In routine practice, the imaging work-up for screening SDHx mutation carriers should include thoraco-abdomino-pelvic computed tomography, head and neck magnetic angiography, and somatostatin receptor scintigraphy. Expert centralized image assessment is recommended.

New strategy for automatic tumor segmentation by adaptive thresholding on PET/CT images.

Tumor delineation is a critical aspect in radiotherapy treatment planning and is usually performed with the anatomical images of a computed tomography (CT) scan. For non-small cell lung cancer, it has been recommended to use functional positron emission tomography (PET) images to take into account the biological target characteristics. However, today, there is no satisfactory segmentation technique for PET images in clinical applications. In the present study, a solution to this problem is proposed. The development of the segmentation technique is based on the threshold's adjustment directly from patients, rather than from phantoms. To this end, two references were chosen: measurements performed on CT images of the selected lesions, and histological measurements of surgically removed tumors. The inclusion and exclusion criteria were chosen to produce references that are assumed to have measured tumor sizes equal to the true in vivo tumor sizes. In total, for the two references, 65 lung lesions of 54 patients referred for FDG-PET/CT exams were selected. For validation, measurements of segmented lesions on PET images using this technique were also compared to CT and histological measurements. For lesions greater than 20 mm, our segmentation technique showed a good estimation of histological measurements (mean difference between measured and calculated data equal to -0.8 ± 9.0%) and an acceptable estimation of CT measurements. For lesions smaller than or equal to 20 mm, the method showed disagreement with the measurements derived from histological or CT data. This novel segmentation technique shows high accuracy for the lesions with largest axes between 2 and 4.5 cm. However, it does not correctly evaluate smaller lesions, likely due to the partial volume effect and/or respiratory motions.

Atypical femoral head osteonecrosis: a case report.

We report the case of a 65-year-old man presented with polymyalgia rheumatica. After a week on corticosteroid (40 mg/d), pain was relieved rapidly. Bone scan, requested to precisely localize osteoarticular lesions, showed high uptake in the external aspect of the head of left femur. In the clinical setting, bone scan and MRI appearances are suggestive of osteonecrosis, probably of recent onset. The final diagnosis of atypical necrosis of the femoral head, most probably secondary to corticoid therapy, was thus established.

18F-FLT and 18F-FDG positron emission tomography for the imaging of advanced well-differentiated gastro-entero-pancreatic endocrine tumours.

PURPOSE: Gastro-entero-pancreatic (GEP) endocrine tumours are a heterogenous group of tumours of variable localization and prognosis. It has been suggested that positron emission tomography (PET) using 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) may have a prognostic value and help to identify patients at risk of progression. [18F]fluoro-3'-deoxy-3'-L-fluorothymidine (18F-FLT) has been recently developed as a PET proliferation tracer. At present, there are no studies investigating its role in GEP. The aim of this prospective study was to assess the value of 18F-FLT-PET for the evaluation of GEP. MATERIALS AND METHODS: Ten patients with biopsy-proven locally advanced or metastasized, well-differentiated GEP neuroendocrine tumours were prospectively enrolled and scheduled for 18F-FDG and 18F-FLT-PET. Images were compared with other conventional diagnostic procedures, namely computed tomography, ultrasound, somatostatin receptor scintigraphy and with clinical and diagnostic follow-up. RESULTS: Evaluation criteria were interpreted in terms of assumed presence of tumoral tissue. According to the patient's status, FDG was positive in five out of the seven patients with stable disease and in two out of the three patients with progressive disease. No positive case was identified by 18F-FLT in either the primary or the metastatic tumour site, whatever the status of patients, and this was probably a reflection of the slow proliferation rate of tumours. CONCLUSION: These preliminary data suggest that 18F-FLT-PET is not a suitable tracer for the evaluation of advanced well-differentiated GEP tumours. FDG showed good diagnostic performance but does not help to identify patients at risk of progression.

Diagnostic management of suspected metastatic thyroid carcinoma: clinical value of octreotide scintigraphy in patients with negative high-dose radioiodine scans.

OBJECTIVES: Somatostatin receptor scintigraphy (SRS) with (111)In-octreotide has been suggested as a potential tool for the detection of recurrent or metastatic differentiated thyroid cancer when no radioiodine uptake can be demonstrated in tumour sites. However, there is no consensus concerning the performance and clinical impact of this examination in such instances. DESIGN AND METHODS: A prospective study was undertaken to evaluate SRS in 43 patients (18 men, 25 women) with papillary (n=20), follicular (n=9), insular (n=6) and oncocytic (n=8) thyroid carcinomas with elevated serum thyroglobulin (Tg) levels and no detected radioiodine uptake. RESULTS: Evaluation criteria were interpreted in terms of an assumed presence of tumoural tissue. Sensitivity of SRS was 51%, clearly lower than that of conventional imaging procedures, and of positron emission tomography using [(18)F]-2-fluoro-2-deoxy-d-glucose, performed in a subset of 27 patients. In addition, we observed two false-positive foci of uptake of octreotide that corresponded to inflammatory pulmonary sites. The sensitivity was higher in patients with Tg levels greater than 50 microg/l (76%) for detecting mediastinal lesions (93%), and in patients with oncocytic cancer (88%). Finally, SRS changed treatment strategy in four patients. CONCLUSION: In differentiated thyroid cancer, SRS is a moderately sensitive method for the detection of lesions unable to concentrate iodine and appears useful only in patients with very high Tg levels or in oncocytic cancer.

Is [18F]-2-fluoro-2-deoxy-d-glucose (FDG) scintigraphy with non-dedicated positron emission tomography useful in the diagnostic management of suspected metastatic thyroid carcinoma in patients with no detectable radioiodine uptake?

OBJECTIVE: Dedifferentiation of thyroid cancer leads to an inability of thyroid cells to concentrate iodine. In these cases, imaging methods that allow an accurate detection of recurrence and/or metastases at an early stage are essential for an adequate management of patients. Positron emission tomography using [18F]-2-fluoro-2-deoxy-d-glucose and a dedicated (dPET-FDG) or non-dedicated (nPET-FDG) camera has been suggested as a potential tool for the detection of tumour foci. DESIGN AND METHODS: This prospective study was undertaken to evaluate nPET-FDG in 51 consecutive patients (18 men, 33 women) with differentiated thyroid cancer (33 papillary, 11 follicular, four insular and three oncocytic (Hurthle-cell) thyroid carcinomas). Selection criteria were high thyroglobulin (Tg) levels (>10 ng/ml off-levothyroxine treatment) and no detectable radioiodine uptake, on a whole body scan performed with a high dose, in the absence of iodine contamination. RESULTS: Results were interpreted in terms of assumed presence of tumoral tIssue. Sensitivity of nPET-FDG was similar to that of conventional imaging modalities (67%). False negative nPET-FDG (n=16) were observed mostly in cases of micro-lesions (lymph nodes or lung metastases). Conversely, nPET-FDG identified new tumoral sites in 11 cases. Better sensitivity was found for nPET-FDG in patients with Tg levels higher than 15 microg/l (P<0.05). On a patient basis, results of nPET-FDG were equivalent to that of dPET-FDG. Finally, nPET-FDG changed treatment strategy in seven patients. CONCLUSIONS: nPET-FDG has a high sensitivity for the detection of tumour sites in patients when pathological iodine uptake cannot be demonstrated and appears to be a useful method in patients with elevated Tg levels, especially when dedicated PET is either unavailable or impractical.

Automated detection of local normalization areas for ictal-interictal subtraction brain SPECT.

UNLABELLED: Whole-brain activity is often chosen to quantitatively normalize peri-ictal and interictal SPECT scans before their subtraction. This use is not justified, because significant and extended modification of the cerebral blood flow can occur during a seizure. We validated and compared 2 automatic methods able to determine the optimal reference region, using simulation and clinical data. METHODS: In the first method, the selected reference region is the intersection of peri-ictal-interictal areas with no significantly different z values. The other method relies on a 3-dimensional iterative voxel aggregation. The increase of the selected volume is stopped by using 2 different variance tests (Levene and SE). These algorithms were tested on 39 epileptic patients and were validated using 1 interictal and 10 peri-ictal scans simulated from the mean image of 22 healthy subjects. RESULTS: In the patient studies, the mean relative activity of the selected regions, compared with whole-brain activity (classic normalization), was 122.6%. Their average relative size (compared with the size of the whole brain) was 33.2% for the z map method, 22.8% for the SE test, and 11.8% for the Levene test. After application of our automatic processes, subtraction of the simulated images revealed a recovery of abnormal regions up to 45% larger than the region obtained with classic normalization. CONCLUSION: These results illustrate the role of normalization on the subtracted peri-ictal and interictal images. Our methods are automatic and objective and give good results on various simulated images. The z map construction is worth considering because it is simple, selects large parts of the brain, and requires little computation time.

Detection of neuroendocrine tumors: 99mTc-P829 scintigraphy compared with 111In-pentetreotide scintigraphy.

UNLABELLED: The aim of this study was to evaluate the diagnostic value of a new somatostatin analog, 99mTc-P829, compared with that of 111In-pentetreotide. METHODS: Forty-three patients (32 men, 11 women; age range, 24-78 y; mean age, 56 y) with biologically or histologically proven neuroendocrine tumors were prospectively included: 11 patients with Zollinger-Ellison syndrome, 16 patients with carcinoid tumors, and 16 patients with other types of functioning (n = 6) or nonfunctioning (n = 10) endocrine tumors. 111In-Pentetreotide planar images (head, chest, abdomen, and pelvis) were obtained 4 and 24 h after injection of 10 microg somatostatin analog labeled with 148 +/- 17 MBq 111In, and SPECT was performed 24 h after injection. Similar (99m)Tc-P829 planar images were obtained at 1, 4-6, and 24 h after injection of 50 microg peptide labeled with 991.6 +/- 187.59 MBq 99mTc. Abdominal SPECT was performed 4-6 h after injection. RESULTS: 111In-Pentetreotide detected 203 tumoral sites in 39 (91%) of 43 patients, whereas 99mTc-P829 detected 77 sites in 28 (65%) of 43 patients (P < 0.005). In the liver, 129 sites (in 24 patients) were detected by 111In-pentetreotide scintigraphy and 34 sites (in 10 patients) were detected by 99mTc-P829 scintigraphy. CONCLUSION: In patients with endocrine tumors, the detection rate of 99mTc-P829 scintigraphy was lower than that of 111In-pentetreotide scintigraphy, which appeared to be more sensitive, especially for liver metastases.