Burden of metastatic bone disease measured on 18F-NaF PET/computed tomography studies as a prognostic indicator in patients with medullary thyroid cancer.

PURPOSE: The aim of the study was to assess the association between the burden of metastatic bone disease measured on F-NaF PET/computed tomography (CT) studies and the overall survival (OS) of patients with medullary thyroid cancer (MTC). METHODS: We retrospectively analyzed 31 patients with MTC who performed 18F-NaF PET/CT studies to assess skeletal metastases. The outcomes of the patients (dead or alive) were established based on the last information available on their files. In the studies considered positives for skeletal metastases, the burden of metastatic bone disease was established calculating the fluoride tumor volume (FTV). The FTV was defined using isocontour thresholds based on percentages of maximal standardized uptake values (SUVmax) in the lesions. These percentages varied from lesion to lesion and were established by visual analysis. The patients were divided into three groups as follows: without skeletal metastases (n = 11), with low FTV (≤50 cm; n = 11) and with high FTV (>50cm; n = 9). The Kaplan-Meier curves were used to analyze the OS in the three groups of patients and the log-rank test was used to determine the statistical significance of the difference between the groups. RESULTS: There were statistically significant differences in the OS between the group with high FTV and the groups of patients with low FTV (P = 0.036) and without skeletal metastases (P = 0.001). There was not a statistically significant difference between the groups of patients with low FTV and without skeletal metastases (P = 0.147). CONCLUSION: In patients with MTC, the burden of metastatic bone disease is associated with OS.

68Ga-DOTATATE PET: temporal variation of maximum standardized uptake value in normal tissues and neuroendocrine tumours.

OBJECTIVES: Higher affinity of Ga compounds to somatostatin receptors (SSTRs) and PET better image resolution increased interest in Ga-labelled somatostatin analogs in the management of neuroendocrine tumours (NETs). This study aimed to evaluate the maximum standardized uptake value (SUVmax) variation in sequential somatostatin analogs-PET in NET patients and identify optimal tumour detection and characterization imaging time. METHODS: Patients with histological or biochemical NET diagnosis performed two to three PET/computed tomography (CT) scans after intravenous injection of Ga-DOTATATE: Early PET [EarlyPET: <15 minutes postinjection (p.i.)], diagnostic PET (DiagPET: 45-90 minutes p.i.) and delayed PET (DelayPE: 90-240 minutes p.i.). Up to five tumour sites and normal tissues had SUVmax determined. Time-SUVmax curves were created for the target lesions and normal organs. Ratios between tumour and liver SUVmax (SUVTU/Liver) and tumour/blood pool (SUVTU/BP) were also calculated. RESULTS: Twenty-nine patients were included, 16 female, mean age of 46.5 ± 14.3 years. Average administered activity was 129.5 ± 29.6 MBq. Kidneys SUVmax was higher in EarlyPET compared with DiagPET (P = 0.04) and DelayPET showed higher SUVmax compared with DiagPET for normal liver, pancreas and kidneys (P = 0.02). No differences were noted between EarlyPET, DiagPET and DelayPET in tumour SUVmax (P > 0.05). SUVTU/Liver and SUVTU/BP did not change between EarlyPET and DiagPET, with a slight decrease in DelayPET. CONCLUSION: Stability in tumour SUVmax values measured at different intervals independently of tumour location, as also in normal tissues as kidneys and liver suggest that a more flexible imaging protocol may be adopted.

Evaluation of 18F-FDG PET-CT as a prognostic marker in advanced biliary tract cancer.

BACKGROUND: Advanced biliary tract cancers have a dismal prognosis. Treatment with gemcitabine plus cisplatin has resulted in a significant improvement in survival; however, early assessment of outcomes poses a challenge. OBJECTIVE: We carried out a prospective study to evaluate the prognostic role of fluorine-18 fluorodeoxyglucose (F-FDG) PET-CT scans in patients with advanced biliary tract cancer. PATIENTS AND METHODS: Patients with advanced unresectable or metastatic biliary tract cancer starting first-line chemotherapy with gemcitabine plus cisplatin underwent F-FDG PET-CT studies at baseline and after two cycles of therapy. The total lesion glycolysis (TLG) measured at baseline as well as the variation in TLG between the two studies were analyzed as prognostic indicators of overall survival. The survival analyses were carried out using Kaplan-Meier curves and the comparison of survival curves was performed using the Breslow test. RESULTS: Of the 42 patients included, 37 had the first F-FDG PET-CT and 27 had the second F-FDG PET-CT. Patients with lower TLG values at baseline or after two cycles of therapy presented a higher median survival than patients with higher baseline TLG values. Patients with a higher decrease in the TLG values between the two studies also had a higher median survival time. However, these results only trended for statistical significance (P values ranging between 0.05 and 0.16). CONCLUSION: Lower baseline TLG measured by F-FDG PET-CT as well as a decrease in metabolic uptake after chemotherapy were associated with a trend toward longer median survival among patients with advanced biliary cancers.

[Comparative study of 18 F-fluorodeoxyglucose imaging with a dual-head coincidence gamma camera with dobutamine stress echocardiography for the assessment of myocardial viability]. / Análise comparativa da captação de 18 fluordesoxiglicose por câmara de cintilação e sistema de coincidência e a ecocardiografia de estresse pela dobutamina na detecção de viabilidade miocárdica.

OBJECTIVE: To compare Dual-Head coincidence gamma camera (DCD-AC) with dobutamine stress echocardiography (DSE) in viability assessment, using functional recovery as the gold standard. METHODS: Twenty-one patients were prospectively studied, with coronary artery disease and severe left ventricular dysfunction undergoing DSE and DCD-AC at baseline and DSE three months after revascularization. RESULTS: Of the 290 segments analyzed, 83% were akinetic, 15% hypokinetic and 2% dyskinetic at rest. DSE identified 68% of these segments as non-viable. DCD-AC identified 56% of these segments as normal (dysfunctional segments with preserved metabolism and perfusion), 30% as viable (preserved metabolism and reduced perfusion) and 14% as non-viable (reduced perfusion and metabolism). Of the DSE non-viable segments, DCD-AC identified 80% as normal or viable and 19.9% as non-viable (p<0.001). In hypokinetic segments viability and normal segments were detected in a higher proportion by both methods (p<0.001). DSE sensibility and specificity were 48.3% and 78.1% respectively. DCD-AC sensibility and specificity was 92.2% and 20.0%. DCD-AC identifies a higher incidence of function improvement in normal segments than in viable and non-viable. CONCLUSION: DCD-AC classified as normal or viable most of the non-viable DSE segments. In assessment of functional recovery segments after three months, DCD-AC showed a high sensibility but low specificity.

Análise comparativa da captacão de 18 fluordesoxiglicose por câmara de cintilacão e sistema de coincidência e a ecocardiografia de estresse pela dobutamina na deteccão de viabilidade miocárdica / Comparative study of 18 F-fluorodeoxyglucose imaging with a dual-head coincidence gamma camera with dobutamine stress echocardiography for the assessment of myocardial viability

OBJETIVO: Comparar a câmara de cintilacão e sistema de coincidência (CC) com a ecocardiografia de estresse pela dobutamina (EED) na deteccão de viabilidade miocárdica, utilizando-se a recuperacão funcional como padrão de referência. MÉTODOS: Vinte e um pacientes com doenca arterial coronária e disfuncão grave do ventrículo esquerdo foram estudados prospectivamente, submetidos a EED e CC, antes da cirurgia de revascularizacão do miocárdio (RM), e a EED, três meses após. RESULTADOS: De 290 segmentos analisados, 83 por cento encontravam-se acinéticos, 15 por cento, hipocinéticos, e 2, discinéticos ao repouso. A EED identificou 68 por cento destes segmentos como não-viáveis. A CC identificou 56 por cento destes segmentos como normais (contratilidade alterada com metabolismo e perfusão preservada), 30 por cento como viáveis (perfusão reduzida e metabolismo preservado) e 14 por cento, como não-viáveis (ausência de metabolismo e perfusão). Entre os não-viáveis pela EED, a CC classificou 80 por cento como normais ou viáveis e 19,9 por cento, como não viáveis (p<0,001). A sensibilidade e especificidade da EED foram de 48,3 por cento e 78,1 por cento, respectivamente. A sensibilidade e especificidade da CC de 92,2 por cento e 20,0 por cento, respectivamente. A CC identificou maior proporcão de recuperacão funcional nos segmentos classificados como normais do que os viáveis e não-viáveis. CONCLUSAO: A CC classificou como normal ou viável a maior parte dos segmentos não-viáveis pela EED. Na avaliacão da recuperacão funcional, três meses após a RM, a CC demonstrou uma alta sensibilidade, porém reduzida especificidade.

Rapid normalization of osseous FDG uptake following traumatic or surgical fractures.

It is known that following a traumatic fracture or surgical intervention, bone scintigraphy reveals positive results for an extended period of time, posing a challenge when evaluating patients for possible malignancy or superimposed osteomyelitis. Previous reports indicate that acute fractures can also result in increased fluorine-18 fluorodeoxyglucose (FDG) accumulation and therefore cause difficulties when patients are evaluated for other indications by FDG-PET. The purpose of this study was to assess the pattern and time course of abnormal FDG uptake following traumatic or surgical fracture. A total of 1,517 consecutive patients who underwent whole-body FDG-PET imaging were retrospectively studied. A history of fractures or orthopedic intervention was obtained from an interview prior to scanning. The FDG-PET results were compared with the results of other imaging studies, including bone scans, radiographs, CT, and MRI, as well as surgical pathology reports. Thirty-seven patients with a known date of traumatic or surgical fracture were identified. Among these, 14 had fractures or surgery within 3 months prior to FDG-PET, while 23 had fractures or surgical intervention greater than 3 months prior to FDG-PET. FDG-PET showed no abnormally increased uptake at the known fracture or surgical sites in 30 of these patients. Notably, in the 23 patients with fractures more than 3 months old, all but one showed no abnormally increased uptake. Furthermore, the positive FDG uptake in this exception was a result of complicating osteomyelitis. In the 14 patients with a history of fracture less than 3 months old, only six had abnormally increased FDG uptake. Following traumatic or surgical fractures, FDG uptake is expected to be normal within 3 months unless the process is complicated by infection or malignancy.

Relação dos níveis séricos de cálcio e paratormônio com a positividade da cintiligrafia das paratiróides / Relation of serum calcium and parathormone levels and positivity of parathyroid scintigraphy

O hiperparatiroidismo primário (HPP) é caracterizado pelo aumento da secreção de PTH, com conseqüente aumento da concentração sérica de cálcio. O diagnóstico é realizado pela dosagem de cálcio e PTH. A cintilografia das paratiróides é solicitada, classicamente, em pacientes com recorrência de HPP após paratiroidectomia, na tentativa de detectar glândulas patológicas ectópicas ou remanescentes. Algumas vezes este exame tem sido solicitado antes do primeiro ato cirúrgico, na tentativa de localizar as glândulas comprometidas e abreviar a duração da cirurgia; na nossa casuística, no entanto, a maioria dos exames solicitados com esta indicação resulta negativa. Comparamos os níveis séricos de cálcio e PTH nos pacientes com cintilografia das paratiróides positiva, com aqueles dos pacientes com cintilografia negativa, a fim de tentar definir níveis com índice maior de positividade na cintilografia. Foram estudados retrospectivamente 74 pacientes consecutivos submetidos à cintilografia das paratiróides. Avaliou-se a utilização dos valores mais baixos de PTH (79pg/mL) e cálcio (l0mg/dL) registrados no grupo com cintilografia positiva como referência para a indicação do exame. No grupo total de pacientes, 17 (23 por cento) apresentaram cintilografia positiva. No subgrupo com valores de PTH >79pg/mL e de cálcio >_10 mg/dL a porcentagem de exames positivos foi de 49 por cento. Concluímos que cintilografias das paratiróides realizadas antes da cirurgia de paratiroidectomia em pacientes com níveis de cálcio sérico abaixo do limite superior da normalidade ou níveis de PTH pouco aumentados são, na maioria das vezes, negativas.

Incidental detection of colon cancer by FDG positron emission tomography in patients examined for pulmonary nodules.

PURPOSE: Fluorodeoxyglucose (FDG) positron emission tomographic (PET) imaging has been used extensively to diagnose cancer with high rates of sensitivity and specificity. One of its applications is to distinguish benign from malignant pulmonary nodules. It is common to observe colonic uptake on whole-body FDG-PET images. Because patients with lung cancer also tend to be in the age group with the highest incidence of colon cancer, the authors tried to assess the efficacy of FDG-PET for detecting occult colon cancer in patients referred for the evaluation of lung nodules. METHODS: The records of 500 consecutive patients referred for the evaluation of pulmonary nodules were reviewed retrospectively. Among the patients, 197 had no previous clinical or radiographic evidence of abnormalities in the gastrointestinal tract, and none had been found to have any cancer before undergoing an FDG-PET study. All colon lesions were verified either by histologic analysis or by clinical course. RESULTS: Among the 197 patients analyzed, 59 had diffuse colonic uptake in various segments of the colon. Seventeen of the patients had focal colonic uptake, five of which were proved to be colon cancer. CONCLUSIONS: The routine use of FDG PET to characterize lung lesions significantly increases the probability of detecting unexpected extrathoracic disease. In these patients, the incidental finding of colon cancer had an important effect on their treatment and may prove to be very cost-effective.

The receiver operating characteristic curve for the standard uptake value in a group of patients with bone marrow metastasis.

PURPOSE: The aim of this work was to determine the standard uptake value (SUV) threshold for differentiating malignant from benign bone lesions. MATERIAL AND METHODS: Ninety-nine bone sites in 33 patients who had undergone a 2-deoxy-2-[18F]fluoro-D-glucose-positron emission tomography (FDG-PET) study for cancer evaluation were studied. In addition to FDG-PET, a bone scan and at least two of the following determinations: magnetic resonance imaging (MRI), computed tomography (CT), and x-ray were conducted in each patient. The bone lesions were considered positive for malignancy if confirmed by clinical follow-up or a high degree of suspicion based on the positive results of at least three (which must include bone scan) out of four other imaging modalities. By these criteria, 39 lesions were considered positive and 60 were considered negative. The SUV values were classified as positive or negative using 61 different values of threshold (range from 1.0 to 7.0). These results were compared with the positive criteria above and reclassified as true positive, true negative, false positive, and false negative. The true-positive fraction and false-positive fraction were calculated for each threshold value. The receiver operating characteristic (ROC) curve was drawn and the best value was determined by visual analysis. RESULTS: The SUV threshold was considered 2.5. Twenty-nine out of 39 bone lesions classified as positive showed a SUV > 2.5. Of the 10 false-negative lesions, seven showed a SUV between 1.1 and 2.0, and three were not detected. Fifty-six out of 60 lesions classified as negative showed a SUV < 2.5. Four lesions were false positive: one was a rib fracture and three were severe degenerative changes in the lumbar spine. Using an SUV threshold of 2.5, the sensitivity was 74.3% and the specificity was 93.3%. CONCLUSION: In our patient population, the optimal SUV to classify a bone lesion as malignant or benign is 2.5.

Qual o valor da análise semi-quantitativa dos exames de FDG-PET no diagnóstico da esclerose mesial temporal? / Does semi-quantitative analysis of FDG-PET have any additional value in the diagnosis of mesial temporal sclerosis?

O objetivo deste estudo foi comparar a análise visual dos exames de FDG-PET com uma análise semi-quantitativa no diagnóstico da esclerose mesial temporal (EMT). MÉTODOS: Este estudo incluiu 21 pacientes com confirmaçäo histopatológica de EMT. Os dados referentes à análise visual foram obtidos dos relatórios dos exames. As imagens de FDG-PET foram analisadas de forma semi-quantitativa utilizando-se regiöes de interesse (ROIs) desenhadas em 19 cortes tomográficos perpendiculares ao maior eixo do lobo temporal. Estas ROIs dividiram cada um dos lobos temporais em três regiöes (lateral, inferior e medial). Um índice de assimetria foi calculado para cada regiäo. RESULTADOS: A análise visual dos exames de FDG-PET demonstrou assimetria no metabolismo em todos os pacientes. Todos, menos 1 dos pacientes foram submetidos a lobectomia temporal do tipo standard do lado descrito como hipometabólico pelo exame de FDG-PET. Utilizando como critério um índice de assimetria maior ou igual a 9 por cento em ao menos uma das regiöes, a análise semi-quantitativa demonstrou assimetria considerada significativa em 18 pacientes. Esta assimetria coincidiu com o lado da cirurgia e foi confirmada como correspondente à área de eslerose em todos menos um dos pacientes (o mesmo paciente citado acima). CONCLUSÄO: A análise semi-quantitativa näo forneceu qualquer informaçäo adicional em relaçäo à interpretaçäo visual das imagens nesta série de pacientes

Hipometabolismo cerebral em pacientes com esclerose mesial temporal demonstrado pelo FDG-PET / Brain hypometabolism in patients with mesial-temporal sclerosis demonstrated by FDG-PET

O objetivo deste estudo foi avaliar a extensao do hipometabolismo cerebral em pacientes com esclerose mesial temporal (EMT). MÉTODO: Este estudo retrospectivo incluiu 21 pacientes que apresentavam epilepsia parcial complexa refrataria à terapia e que foram selecionados para cirurgia após análise extensa que incluía: EEG de superfície e estudos de neuroimagem (PET, SPECT e ressonância magnética). Todos os pacientes foram submetidos a intervençao cirúrgica e tiveram confirmaçao histológica de EMT. Uma análise semi-quantitativa foi realizada, utilizando regioes de interesse (ROIs) nas seguintes estruturas: lobos frontais, parietais e occipitais, gânglios da base, tálamos, cerebelo e três diferentes regioes nos lobos temporais, que compreendiam o córtex medial, inferior e lateral. Um índice de assimetria (IA) foi calculado, comparando as contagens por pixel nas estruturas homólogas em ambos os hemisférios cerebrais. Os IAs das diferentes estruturas foram entao correlacionados. RESULTADOS: Uma correlaçao significativa foi demonstrada entre os IAs do córtex medial dos lobos temporais e aqueles dos lobos frontais, dos lobos parietais, dos gânglios da base e dos tálamos (r = 0,72, 0,62, 0,47 e 0,47 respectivamente com p < 0,05 ). Foi demonstrada correlaçao altamente significativa dos IAs das 3 regioes do lobo temporal entre si (chegando a 0,86 entre os IAs das regioes mediais do lobo temporal e os IAs das regioes inferiores). CONCLUSAO: Esses dados indicam que o hipometabolismo se estende além do foco epiléptico no lobo temporal em pacientes com epilepsia parcial complexa relacionada a EMT. O metabolismo na porçao medial do lobo temporal é mais correlacionado com o metabolismo no lobo frontal do que com aquele de outras estruturas cerebrais externas aos lobos temporais. Os mecanismos fisiopatológicos envolvidos no hipometabolismo continuam controversos