[18F]FDG PET/CT in Short-Term Complications of COVID-19: Metabolic Markers of Persistent Inflammation and Impaired Respiratory Function.

SARS-CoV-2 virus infects organs other than the lung, such as mediastinal lymph nodes, spleen, and liver, but, to date, metabolic imaging studies obtained in short-term follow-ups of patients hospitalized with severe COVID-19 infection are rare. Our objective was to evaluate the usefulness of [18F]FDG-PET/CT in the short-term follow-up of patients admitted for COVID-19 pneumonia and to explore the association of the findings with clinical prognostic markers. The prospective study included 20 patients with COVID-19 pneumonia (November 2020-March 2021). Clinical and laboratory test findings were gathered at admission, 48-72 h post-admission, and 2-3 months post-discharge, when [18F]FDG-PET/CT and respiratory function tests were performed. Lung volumes, spirometry, lung diffusion capacity for carbon monoxide (DLCO), and respiratory muscle strength were measured. Volumetric [18F]FDG-PET/CT results were correlated with laboratory and respiratory parameters. Eleven [18F]FDG-PET/CT (55%) were positive, with hypermetabolic mediastinal lymphadenopathy in 90.9%. Mediastinal lesion's SUVpeak was correlated with white cells' count. Eleven (55%) patients had impaired respiratory function, including reduced DLCO (35%). SUVpeak was correlated with %predicted-DLCO. TLG was negatively correlated with %predicted-DLCO and TLC. In the short-term follow-up of patients hospitalized for COVID-19 pneumonia, [18F]FDG-PET/CT findings revealed significant detectable inflammation in lungs and mediastinal lymph nodes that correlated with pulmonary function impairment in more than half of the patients.

Utilidad de la PET/TC con 18F-fluorocolina en la recidiva bioquímica del cáncer de próstata: relevancia de la cinética del PSA y la terapia hormonal / Usefulness of 18F-fluorocoline PET/CT in prostate cancer patients with biochemical recurrence: Influence of PSA kinetics and hormone therapy

Objetivo: Evaluar la capacidad de la 18F-fluorometilcolina (FCH) tomografía por emisión de positrones/tomografía computarizada (PET/TC) en la detección de la enfermedad en la recidiva bioquímica del cáncer de próstata, su correlación con la cinética del antígeno prostático específico (PSA) y la influencia de la terapia hormonal antiandrogénica. Pacientes y métodos: Estudio observacional y retrospectivo, que incluyó a pacientes con cáncer de próstata y criterios de recidiva bioquímica y/o resistencia a la castración, según la Asociación Europea de Urología. Los resultados de la FCH PET/TC se categorizaron en dos grupos (positivo vs. negativo) utilizando como gold estándar la anatomía patológica, otras pruebas de imagen y/o seguimiento clínico. Se estudió la relación entre la FCH PET/TC y la cinética del PSA (PSA en el momento de la exploración [trigger-PSA], tiempo de duplicación [PSAdt] y velocidad de ascenso [PSAva]) y se analizó la influencia de la terapia hormonal. Resultados: Se incluyeron 203 pacientes. La tasa de detección global de la FCH PET/TC fue del 43,3%. El grupo de pacientes con FCH PET/TC positiva mostró una cinética de PSA más agresiva (PSAdt: 7,5±7,5meses y PSAva 8,37±14,8ng/ml/a) que el grupo FCH PET/TC negativa (PSAdt: 14,5±7,6meses y PSAva: 1,8±3,7ng/ml/a). La tasa de detección de la FCH-PET/TC en el subgrupo con resistencia a la castración fue del 89,1%, significativamente mayor a la tasa del 29,9% del grupo con tratamiento curativo, p <0,001. Conclusiones: La FCH PET/TC es útil en la detección de la enfermedad en la recidiva bioquímica del cáncer de próstata, especialmente en los pacientes con terapia hormonal o cinética del PSA más agresiva

Purpose: To evaluate the capacity of 18f-fluorocholine positron emission tomography/computed tomography (FCH PET/CT) to detect biochemical recurrence of prostate cancer and to determine the correlation with PSA kinetics and influence of antiandrogen hormone therapy. Patients and methods: Observational and retrospective study, which included patients with prostate cancer and criteria for biochemical recurrence and/or resistance to castration, according to the European Association of Urology. FCH PET/CT results were classified as positive or negative, using as gold standard the pathology report, findings of other imaging test, and/or clinical follow-up results. The correlation between FCH PET/CT and PSA kinetics (PSA at the time of exploration [PSA-trigger], doubling time [PSAdt] and velocity [PSAva]) was studied and the influence of hormone therapy was analysed. Results: The study included 203 patients. The FCH PET/CT detection rate was 43.3%. The group of patients with FCH PET/CT positive showed more aggressive PSA kinetics (PSAdt: 7.5 months and PSAva 8.37±14.8ng/ml/a) than the FCH PET/CT negative group (PSAdt: 14.5±7.6 months and PSAva: 1.8±3.7ng/ml/a). The detection rate of FCH PET/CT in the subgroup with castration resistance was 89.1%, significantly higher than in the group with radical treatment at 29.9%, p<.001. Conclusions: FCH PET/CT is useful to detect biochemical recurrence of prostate cancer, especially in patients who receive hormone therapy or more aggressive PSA kinetics

Usefulness of 18F-fluorocoline PET/CT in prostate cancer patients with biochemical recurrence: Influence of PSA kinetics and hormone therapy. / Utilidad de la PET/TC con 18F-fluorocolina en la recidiva bioquímica del cáncer de próstata: relevancia de la cinética del PSA y la terapia hormonal.

PURPOSE: To evaluate the capacity of 18f-fluorocholine positron emission tomography/computed tomography (FCH PET/CT) to detect biochemical recurrence of prostate cancer and to determine the correlation with PSA kinetics and influence of antiandrogen hormone therapy. PATIENTS AND METHODS: Observational and retrospective study, which included patients with prostate cancer and criteria for biochemical recurrence and/or resistance to castration, according to the European Association of Urology. FCH PET/CT results were classified as positive or negative, using as gold standard the pathology report, findings of other imaging test, and/or clinical follow-up results. The correlation between FCH PET/CT and PSA kinetics (PSA at the time of exploration [PSA-trigger], doubling time [PSAdt] and velocity [PSAva]) was studied and the influence of hormone therapy was analysed. RESULTS: The study included 203 patients. The FCH PET/CT detection rate was 43.3%. The group of patients with FCH PET/CT positive showed more aggressive PSA kinetics (PSAdt: 7.5 months and PSAva 8.37±14.8ng/ml/a) than the FCH PET/CT negative group (PSAdt: 14.5±7.6 months and PSAva: 1.8±3.7ng/ml/a). The detection rate of FCH PET/CT in the subgroup with castration resistance was 89.1%, significantly higher than in the group with radical treatment at 29.9%, p<.001. CONCLUSIONS: FCH PET/CT is useful to detect biochemical recurrence of prostate cancer, especially in patients who receive hormone therapy or more aggressive PSA kinetics.

Relevance of BRAF and NRAS mutations in the primary tumor and metastases of papillary thyroid carcinomas.

BACKGROUND: Multifocality of papillary thyroid carcinoma (PTC) is common. BRAF and NRAS mutations are the most frequent genetic alterations in PTC. The purpose of this study was to determine the distribution and relevance of BRAFT1799A and NRAS mutations in PTC. METHODS: BRAFT1799A and NRAS mutations were evaluated in 195 intrathyroid or metastatic foci from 29 patients with multifocal PTC. RESULTS: BRAFT1799A mutation was positive in 46.7% of the 59 intrathyroid and 136 metastatic foci (91/195 foci). Heterogeneous BRAF pattern was observed in 51.7% patients (15/29 patients). Irrespective of BRAF status at diagnosis (thyroid or nodes), all patients with recurrent PTC presented BRAF-mutated metastases during follow-up. All foci were negative for NRAS mutations. CONCLUSION: BRAF but not NRAS mutations were heterogeneously distributed among primary tumor, nodal sites, and recurrent disease. The BRAF status of metastases generated during the follow-up can differ from the status of foci at diagnosis. © 2016 Wiley Periodicals, Inc. Head Neck 38: 1772-1779, 2016.

Novel BRAFI599Ins Mutation Identified in a Follicular Variant of a Papillary Thyroid Carcinoma: A Molecular Modeling Approach.

OBJECTIVE: BRAF mutations are the most common genetic alteration found in papillary thyroid carcinoma (PTC). Approximately, 90% correspond to BRAFV600E, although other less common BRAF mutations have been described. The aim of this study was to describe a new mutation on BRAF gene discovered on the previous thyroid cytology of a patient diagnosed with a follicular variant of PTC (FV-PTC). METHODS: The mutation was identified by independent cloning of the 2 alleles and direct sequencing in the previous cytology and tumor tissue samples from a patient diagnosed with FV-PTC. To elucidate the effect of the mutation on the structure and hence on the activating mechanism of the protein, the structures of BRAFI599Ins, BRAFT599Ins, BRAFV599Ins and BRAFV600E were modeled by using the reconstructed wild-type BRAF (BRAFWT) crystal structure. RESULTS: The novel mutation in BRAF consisted in the in-frame insertion of 3 nucleotides (TAA) after nucleotide 1795, resulting in the incorporation of an extra isoleucine residue at position 599 (BRAFI599Ins) of the protein. The structural comparison of BRAFI599Ins, BRAFT599Ins, BRAFV599Ins with BRAFWT, and BRAFV600E models revealed that the overall shape of the kinase was conserved in the protein produced by this novel mutation, except for the displacement of the activation loop (A-loop), as a direct consequence of the increase in loop size, and the exposition of 1 of the 2 residues involved in BRAF activation (T599), probably facilitating its phosphorylation. CONCLUSION: BRAFI599Ins mutation constitutes a new BRAF mutation affecting the length of the A-loop, which most likely facilitates BRAF activation by altering the A-loop conformation.

Ability of FDG-PET/CT in the detection of gallbladder cancer.

PURPOSE: To assess the value of FDG-PET/CT in the evaluation of gallbladder carcinomas (GBC). METHODS: A prospective cohort of patients with suspicion of or confirmed GBC was studied with FDG-PET/CT. Diagnostic accuracy parameters were calculated in comparison with pathology and/or the clinical course of patients. Clinical impact of PET/CT imaging was estimated. RESULTS: Forty-nine patients were enrolled (34 malignant tumors, 15 benign lesions; 37 staging, 12 restaging). Overall diagnostic accuracy was 95.9% for the diagnosis of the primary lesion, 85.7% for lymph node involvement and 95.9% for metastatic disease. Mean SUVmax in malignant gallbladder lesions was 7.92 ± 6.25 Analysis of ROC curves showed a SUVmax cut-off value of 3.62 for malignancy (S: 78.1%; Sp: 88.2%). Diagnostic accuracy in the restaging group reached 100%. FDG-PET/CT changed the management of 22.4% of the population. COMMENTS: Diagnosis of malignancy or benignity of suspicious gallbladder lesions is accurately made with FDG PET/CT, allowing a precise staging of GBC due to its ability to identify unsuspected metastatic disease. SUVmax has a complementary role in addition to visual analysis.

Presencia de la mutación BRAF T1799A en el tumor primario como indicador de riesgo, recidiva o persistencia de carcinoma papilar de tiroides / BRAF T1799. A mutation in the primary tumor as a marker of risk, recurrence, or persistence of papillary thyroid carcinoma

Antecedentes y objetivo. La mutación BRAFT1799A se ha relacionado con características tumorales de más agresividad, recidiva tumoral y persistencia de carcinoma papilar de tiroides (CPT), aunque no todos los estudios apoyan esta asociación. En éste, se analiza la asociación entre la presencia de la mutación BRAFT1799A en el tumor primario de pacientes con CPT y las características clinicopatológicas de riesgo, recidiva y persistencia tumoral. Pacientes, material y método. Hemos seguido a 97 pacientes intervenidos de CPT durante una mediana de 64,1 meses. La mutación BRAFT1799A se determinó en ácido desoxirribonucleico procedente de muestras de la tiroidectomía inicial mediante amplificación por PCR del exón 15 del gen braf y análisis de los fragmentos de restricción con la enzima TspRI. Los casos positivos fueron confirmados por secuenciación. La asociación estadística entre la mutación BRAFT1799A y las diferentes variables se estudió mediante los correspondientes tests de contraste de hipótesis más regresión logística. Resultados. El 46,4% de los pacientes eran positivos para la mutación BRAFT1799A. Tras análisis bivariante y multivariante, la mutación BRAFT1799A sólo se asociaba con edad superior a 60 años (odds ratio [OR] = 5,5; intervalo de confianza [IC] del 95%, 1,4-21,9; p=0,019) y tamaño de 1cm o superior (OR=3,6; IC del 95%, 1,2-10,3; p=0,016). No se asociaba con subtipos histológicos, metástasis, recidiva, necesidad de nuevos tratamientos ablativos con I131 o de otras intervenciones quirúrgicas debidas a la aparición de metástasis o persistencia de enfermedad al final del seguimiento. Conclusiones. La mutación BRAFT1799A está asociada a edad superior a 60 años y tamaño tumoral de 1cm o mayor, pero no con otras características clinicopatológicas, recidiva tumoral o persistencia de enfermedad (AU)

Background and objective. The BRAFT1799A mutation is reported to be associated to aggressive, persistent, and recurrent tumor in papillary thyroid carcinoma (PTC) patients. Association of the BRAFT1799A mutation in the primary tumor with the clinicopathological characteristics of PTC patients was analyzed. Patients, material and methods. Ninety-seven PTC patients were followed up for a median of 64.1 months. The BRAFT1799A mutation was analyzed in DNA from initial thyroidectomy biopsies by PCR amplification and restriction fragment length polymorphism using TspRI enzyme. Positive cases were confirmed by DNA sequencing. Statistical association between BRAFT1799A mutation and clinicopathological characteristics was analyzed by the relevant hypothesis tests and logistic regression. Results. 46.4% of patients were positive for the BRAFT1799A mutation. Bivariate and multivariate analysis showed the BRAFT1799A mutation to be only associated to age over 60 years (odds ratio [OR] = 5.5; 95% confidence interval [CI],1.4-21.9; p=0.019) and to tumor size of 1cm or greater (OR=3.6, 95% CI, 1.2-10.3; p=0.016). The BRAFT1799A mutation was not associated to histological subtype, metastasis, recurrence, more aggressive treatments (ablative I131 therapy or surgery), or PTC persistence at the end of follow-up. Conclusions. The BRAFT1799A mutation is associated to age over 60 and a tumor size of 1cm or greater, but not to other clinicopathological characteristics, tumor recurrence or PTC persistence (AU)

[BRAF(T1799A) mutation in the primary tumor as a marker of risk, recurrence, or persistence of papillary thyroid carcinoma]. / Presencia de la mutación BRAF(T1799A) en el tumor primario como indicador de riesgo, recidiva o persistencia de carcinoma papilar de tiroides.

BACKGROUND AND OBJECTIVE: The BRAF(T1799A) mutation is reported to be associated to aggressive, persistent, and recurrent tumor in papillary thyroid carcinoma (PTC) patients. Association of the BRAF(T1799A) mutation in the primary tumor with the clinicopathological characteristics of PTC patients was analyzed. PATIENTS, MATERIAL AND METHODS: Ninety-seven PTC patients were followed up for a median of 64.1 months. The BRAF(T1799A) mutation was analyzed in DNA from initial thyroidectomy biopsies by PCR amplification and restriction fragment length polymorphism using TspRI enzyme. Positive cases were confirmed by DNA sequencing. Statistical association between BRAF(T1799A) mutation and clinicopathological characteristics was analyzed by the relevant hypothesis tests and logistic regression. RESULTS: 46.4% of patients were positive for the BRAF(T1799A) mutation. Bivariate and multivariate analysis showed the BRAF(T1799A) mutation to be only associated to age over 60years (odds ratio [OR] = 5.5; 95% confidence interval [CI],1.4-21.9; p=0.019) and to tumor size of 1cm or greater (OR=3.6, 95% CI, 1.2-10.3; p=0.016). The BRAF(T1799A) mutation was not associated to histological subtype, metastasis, recurrence, more aggressive treatments (ablative I(131) therapy or surgery), or PTC persistence at the end of follow-up. CONCLUSIONS: The BRAFT1799A mutation is associated to age over 60 and a tumor size of 1cm or greater, but not to other clinicopathological characteristics, tumor recurrence or PTC persistence.

Is FDG-PET suitable for evaluating neoadjuvant therapy in non-small cell lung cancer? Evidence with systematic review of the literature.

BACKGROUND: Neoadjuvant therapy response assessment is crucial in patients with non-small cell lung cancer (NSCLC). FDG-PET has emerged as a valuable tool for defining therapy response assessment in other tumours. AIM: To systematically review publications appearing in the literature describing induction therapy response assessment with FDG-PET in NSCLC. METHODS: We performed a bibliographic search and selected only prospective studies in order to include the highest levels of evidence. RESULTS: Nine of 497 potentially relevant publications were selected. The ranges of sensitivity, specificity, positive predictive value and negative predictive value for primary tumour response assessment were 80-100%, 0-100%, 42.9-100%, and 66.7-100%, respectively. Pooling data for N2 restaging after neoadjuvant response the overall sensitivity was 63.8% (95% CI, 53.3-73.7%) and overall specificity was 85.3% (95% CI, 80.4-89.4%). CONCLUSION: The results of the analysis do not support the use of FDG-PET as the only re-assessment tool for mediastinal lymph node evaluation for routine clinical use. FDG-PET seems to predict primary tumour response to induction therapy but it could not be shown by pooling analysis.

Utilidad de la tomografía por emisión de positrones en el manejo de los cánceres de cuerpo de útero / Utility of positron emission tomography in the management of uterine body cancer

En la actualidad, la estadificación de los tumoresdel cuerpo uterino es esencialmente quirúrgica. Noexiste consenso ni protocolos definidos para elseguimiento de este tipo de neoplasias. Lastécnicas de diagnóstico por imagen son solicitadasa criterio del clínico, habitualmente ante lasospecha de recurrencia, recidiva o diseminaciónde la enfermedad. Las técnicas de imagenestructural (tomografía computarizada y resonanciamagnética) presentan ciertas limitaciones para ladetección de recurrencias. La tomografía poremisión de positrones es una técnica de imagenfuncional cuya utilidad se ha demostrado enmultitud de neoplasias, que está suscitando ungran interés en los últimos tiempos en el campo dela oncología ginecológica. Se ha realizado unanálisis de los resultados de la bibliografíacientífica disponible sobre la utilidad de estatécnica en los carcinomas endometriales y lossarcomas de útero, tanto en su diagnóstico inicialcomo en su seguimiento

Currently, uterine body tumors are basicallysurgically staged. Established consensus or definedprotocols for the follow up of these neoplasms arelacking. Imaging techniques are usually requestedbased on the clinician’s criteria, usually suspicionof disease recurrence or progression. Structuralimaging techniques, such as computed tomographyor magnetic resonance imaging, present somelimitations in the detection of recurrent disease.Positron emission tomography is a functionalimaging technique with proven utility inneoplasms. In the last few years, interest in thistechnique has grown in the field of gynecologiconcology. We performed a literature review on theutility of positron emission tomography in the evaluation of endometrial cancers and uterinesarcomas, both in initial diagnosis and follow-up

Diagnostic accuracy of 201Thallium-SPECT and 18F-FDG-PET in the clinical assessment of glioma recurrence.

PURPOSE: Reliable differential diagnosis between tumour recurrence and treatment-induced lesions is required to take advantage of new therapeutic approaches to recurrent gliomas. Structural imaging methods offer a high sensitivity but a low specificity, which might be improved by neurofunctional imaging. This study aimed to test the hypothesis that incorporation of 18-fluoro-deoxy-glucose positron emission tomography (FDG-PET) increases the accuracy of this differential diagnosis obtained with 201Tl chloride-single-photon emission computed tomography (201Tl-SPECT). MATERIALS AND METHODS: Seventy-six patients (mean age 47.72 +/- 16.19 years) under suspicion of glioma recurrence, 42% with low-grade and 58% with high-grade lesions, were studied by (201)Tl-SPECT and FDG-PET, reporting results under blinded conditions using visual analysis. Tumour was confirmed by histological confirmation (23 patients) or clinical and structural neuroimaging follow-up (mean of 2.6 years). RESULTS: This population had a high disease prevalence (72%). Globally, highest sensitivity was obtained using 201Tl-SPECT assessed with MRI (96%) and highest specificity using FDG-PET + MRI (95%). FDG-PET appeared slightly better for confirming tumour recurrence, whereas 201Tl-SPECT was superior for ruling out possible recurrence (disease present in 38% of FDG-PET negative explorations). In the high-grade subgroup, there were no false-positive examinations (specificity: 100%), but sensitivity differed among techniques (201Tl-SPECT : 94%; 201Tl-SPECT + MRI: 97%; FDG-PET + MRI: 83%). In the low-grade subgroup, 201Tl-SPECT + MRI showed highest sensitivity (95%) and lowest posttest negative probability (9%); FDG-PET + MRI offered highest specificity (92%) with a posttest negative probability of 35%. CONCLUSIONS: FDG-PET does not clearly improve the diagnostic accuracy of (201)Tl-SPECT, which appears to be a more appropriate examination for the diagnosis of possible brain tumour recurrence, especially for ruling it out.

Positron emission tomography with 2-[18F]-fluoro-2-deoxy-D-glucose in the evaluation of postoperative endometrial cancer patients

Objective To evaluate the usefulness of positron emission tomography with 2-[18F]fluoro-2-deoxy-D-glucose (FDG-PET) in the follow-up of endometrial cancer patients with suspicion of recurrence due to elevated serum tumour markers and suggestive conventional imaging findings. Material and methods A retrospective review was conducted of 17 FDG-PET studies performed in 11 patients with a previous diagnosis of endometrial cancer (6 patients underwent 2 studies) between April 2002 and October 2005. Mean age of patients was 63.4 yrs (range, 52-69 yrs), and mean time since diagnosis was 56 months (range, 11 months - 12 yrs). Initially, 7 patients were in stage I, 3 in stage III, and 1 in stage IV (FIGO classification). Histologically, they corresponded to 8 endometrioid and 3 non-endometrioid cancers. Results FDG-PET showed infradiaphragmatic uptake in three patients and disseminated disease in seven; findings were negative in one patient. Computed tomography (CT, n=7) or magnetic resonance (MRI, n=7) images revealed infradiaphragmatic lesions in five patients and visceral lesions in two. All patients showed elevated serum tumour markers (CA125, n=9; CA19.9, n=2; CA15.3, n=2). FDG-PET results modified the information provided by conventional imaging techniques in seven patients and provided no additional information in the remaining four. There was histological confirmation of lesions in two patients. Nine patients were clinically followed up, including imaging studies (mean follow-up, 8.7 months; range, 3-20 months).

Diagnosis efficacy of structural (CT) and functional (FDG-PET) imaging methods in the thoracic and extrathoracic staging of non-small cell lung cancer.

PURPOSE: To evaluate the efficacy of FDG-PET in the definition of tumour lung node lesions and to compare the diagnostic validity of CT and FDGPET in the staging of patients with non-small cell lung cancer (NSCLC). MATERIAL AND METHODS: Patients with clinical suspicion of potentially resectable NSCLC (n = 108) were studied by standard procedures in our setting, including fibrobronchoscopy, transthoracic fine-needle aspiration, thoracoabdominal CT and FDG-PET. PET images were analysed by researchers blinded to results of other imaging modalities. Definitive tumour diagnosis was by histopathological study in patients who underwent surgery and by specific imaging methods and biopsy, when available, in patients who did not. Diagnostic accuracy was evaluated by comparing CT/PET results with the definitive diagnosis. RESULTS: In 13% of patients, no FDG-PET findings were observed and the histological study was negative for tumour. In 22% of patients, FDG-PET detected metastatic disease (M0 by CT). For mediastinal involvement, global diagnostic accuracy was 0.90 with FDG-PET and 0.59 with CT. False positive FDG-PET findings were produced by inflammatory conditions and false negative findings by the small size or proximity of lymph nodes to primary tumour. Mediastinal staging by CT and FDG-PET was correct in 56% and 87% of patients, respectively. CT indicated mediastinal invasion in 17% of patients with no FDG-PET finding of mediastinal involvement. Conversely, mediastinal spread was undetected by CT in 14% of patients with FDG-PET findings of mediastinal involvement. CONCLUSIONS: Although complementary, the functional method (FDG-PET) is significantly superior to the structural method (CT) for detection of mediastinal tumour disease.

Fluorine-18 fluorodeoxyglucose PET in the preoperative staging of colorectal cancer.

INTRODUCTION: In patients with colorectal cancer (CC), preoperative evaluation and staging should focus on techniques that might alter the preoperative or intraoperative surgical plan. Conventional imaging methods (CT, MRI) have low accuracy for identifying the depth of tumour infiltration and have limited ability to detect regional lymph node involvement. The aim of this study was to evaluate the utility of FDG-PET in the initial staging of patients with CC in comparison with conventional staging methods and to determine its impact on therapeutic management. METHODS: One hundred and four patients with a diagnosis of CC (53 males and 51 females; mean age 66.76+/-12.36 years), selected prospectively, were studied for staging using a standard procedure (CT) and FDG-PET. When possible, the reference method was histology. RESULTS: In 14 patients, surgery was contraindicated by FDG-PET owing to the extent of disease (only 6/14 suspected by CT). FDG-PET revealed four synchronous tumours. For N staging, both procedures showed a relatively high specificity but a low diagnostic accuracy (PET 56%, CT 60%) and sensitivity (PET 21%, CT 25%). For M assessment, diagnostic accuracy was 92% for FDG-PET and 87% for CT. FDG-PET results led to modification of the therapy approach in 50% of patients with unresectable disease. FDG-PET findings were important, revealing unknown disease in 19.2%, changing the staging in 13.46% and modifying the scope of surgery in 11.54% (with a change in the therapeutic approach in 17.85% of those patients with rectal cancer). CONCLUSION: Compared with conventional techniques, FDG-PET appears to be useful in pre-surgical staging of CC, revealing unsuspected disease and impacting on the treatment approach.

Application of modern imaging methods in diagnosis of gallbladder cancer.

The poor prognosis of gallbladder cancer (GBC) is related to its dissemination capacity and usually late diagnosis due to its non-specific clinical appearance. Recent improvements in hepatobiliary surgery have underlined the importance of an early specific diagnosis, which requires a multidisciplinary approach and, when possible, specialized equipment. The first step in an early diagnosis is to identify patients in the appropriate epidemiological setting (e.g., incidental finding, chronic cholecystitis) for the correct interpretation of test results. It is desirable to enhance the sensitivity of the initial ultrasound (US) examination by use of the appropriate technology in skilled specialist hands. When GBC is suggested by US findings, FDG-PET can be considered complementary to establish the benign/malignant nature of the lesion and to obtain a primary staging study. If GBC is confirmed, thin slice spiral CT can contribute valuable information on local spread. In this regard, recent hybrid PET-CT systems provide structural and functional information simultaneously and may offer early and accurate T, N, and M staging with an improved specificity.

Positron-emission tomography with fluorine-18-fluoro-2-deoxy-D-glucose for gallbladder cancer diagnosis.

BACKGROUND: Recent advances in hepatobiliary surgery have underscored the need for presurgical diagnosis of gallbladder cancer. Frequently, clinical presentation, biochemical analysis, and structural ultrasound or computed axial tomography images do not enable definitive differentiation of cholecystitis or cholethiasis from gallbladder cancer. The aim of this study was to evaluate the role of fludeoxy glucose-positron-emission tomography (FDG-PET) in establishing the benign or malignant nature of gallbladder lesions. METHODS: A case series of 16 patients with clinical symptoms suggestive of biliary colic or chronic cholecystitis and with inconclusive ultrasound and/or computed axial tomography findings for presence of gallbladder cancer were studied by FDG-PET. RESULTS: FDG-PET showed a sensitivity of 0.80, a specificity of 0.82, and positive and negative predictive values of 0.67 and 0.90, respectively. There was 1 false- negative result in 1 patient with mucinous adenocarcinoma and 2 false-positive results in 1 patient with tuberculoid granulomatous reaction and 1 patient with polypoid lesion with adenomyomatosis. CONCLUSIONS: FDG-PET may be of utility to establish the diagnosis of gallbladder cancer in patients with nonspecific clinical and imaging findings.

(201)Tl-SPECT in low-grade gliomas: diagnostic accuracy in differential diagnosis between tumour recurrence and radionecrosis.

PURPOSE: The aim of this work was to describe the usefulness of a simple (201)Tl single-photon emission computed tomography (SPECT) technique in the differential diagnosis between tumour recurrence and radionecrosis during the follow-up of patients treated for low-grade gliomas. METHODS: The study population comprised 84 patients treated for low-grade gliomas who showed suspicion of tumour recurrence during their follow-up. All patients were examined by neuro-anatomical imaging procedures (CT, MRI) and (201)Tl-SPECT. (201)Tl-SPECT images were assessed by visual analysis based only on the information on the prescription form and by estimation of the uptake index (ratio of mean counts in the lesion to those in the contralateral mirror area). Examiners were blinded to the results of other tests. RESULTS: Under these conditions, the neuro-anatomical procedures yielded 26.2% inconclusive reports, with a global diagnostic accuracy of 0.61, a sensitivity of 0.63 and a specificity of 0.59. The global diagnostic accuracy for (201)Tl-SPECT was 0.83, with a sensitivity of 0.88 and a specificity of 0.76. Diagnostic pitfalls were observed in regions with physiological (201)Tl uptake, i.e. the posterior cranial fossa, diencephalon, lateral ventricles and cavernous and longitudinal venous sinuses. An uptake index cut-off value of 1.25 showed a sensitivity of 0.90 and specificity of 0.80 for detection of tumour activity. CONCLUSION: (201)Tl-SPECT has adequate diagnostic accuracy to be part of routine algorithms in the follow-up of patients with low-grade glioma suspected of tumour recurrence, as an alternative to neuro-anatomical procedures and not solely as a complementary test.