Dual-Time-Point 18F-FDG PET/CT in Infective Endocarditis: Impact of Delayed Imaging in the Definitive Diagnosis of Endocarditis.

Infective endocarditis (IE) is a major public health condition due to the associated high morbidity and mortality. Our objective was to evaluate the utility of dual-time 2-deoxy-2-[18F] fluoro-D-glucose (18F-FDG) Positron Emission Tomography/Computed Tomography (PET/CT) imaging in the diagnosis of active IE in patients with suspected native valve endocarditis (NVE) and prosthetic valve endocarditis (PVE). For this purpose, a retrospective study was carried out, including patients suspicious of NVE or PVE who underwent a dual-time-point 18F-FDG PET/CT. A final diagnosis was established by the Endocarditis Team after patient follow-up using all the available findings. Sixty-nine patients were assessed. A final diagnosis of NVE was established in 3 patients of the 34 by 18F-FDG PET/CT and in the case of PVE was established in 20 patients of the 35. A statistically significant association was found when evaluating the association between PET diagnosis at early acquisition and final diagnosis of IE (χ2 = 30.198, p < 0.001) and PET diagnosis at delayed acquisition for final diagnosis of IE (χ2 = 9.412, p = 0.002). Delayed PET/CT imaging determined the IE diagnosis in 16/58 of the studies. In conclusion, delayed 18F-FDG PET/CT imaging seems to be useful in improving the definitive diagnosis of IE.

Second radioiodine treatment in patients with differentiated thyroid carcinoma: Causes and effects.

INTRODUCTION: Patients with incomplete response to initial therapy of thyroid cancer can be managed with ongoing observation or potentially additional therapies. Our aim was to assess the effect of a second radioactive iodine treatment (RAIT) and its relationship with causes and clinical variables. MATERIAL AND METHODS: Patients undergoing a second RAIT for biochemical or structural incomplete response to initial therapy of DTC were retrospectively included (n=120). They were categorised based on the American Thyroid Association (ATA) classification of response to initial therapy. Patients were reclassified in the following 6-18 months after second RAIT based on imaging findings and measurements of thyroglobulin and antithyroglobulin antibody levels. The associations of a downgrading of response category and progression-free survival (PFS), and the related variables, were evaluated. RESULTS: Sixty-six patients (55%) had a downgrading on ATA response category after second RAIT. A significant interdependence of causes for second RAIT and outcomes was found (χ2=29.400, p=0.001), with patients with neck reoperation showing a higher rate of indeterminate or excellent responses. A significant association between ATA response to second RAIT and absence of structural progression was found (χ2=44.914, p<0.001), with less structural progression in patients with downgrading on ATA response (χ2=30.914, p<0.001). There was also significant interdependence to some clinical variables, such as AJCC stage (χ2=8.460, p=0.015), ATA risk classification (χ2=10.694, p=0.005) and initial N stage (χ2=8.485, p=0.004). CONCLUSIONS: In selected cases, a second RAIT could lead to more robust responses with a potential improvement in prognosis in patients with incomplete response to initial DTC treatment.

18 F-FDG PET/CT to Spare Malignancy in a Rare Case of Lung Endometriosis.

ABSTRACT: Lung endometriosis is a rare condition. A 44-year-old woman with known lung endometriosis and radiological follow-up showed progression of bilateral lung affection at control CT, with an enlarged solid nodule with respect to previous control. 18 F-FDG PET/CT was performed to assess that lesion and to guide biopsy. PET images showed the multiple known nodules with pathological tracer uptake.

Correlation of Global and Regional Amyloid Burden by 18 F-Florbetaben PET/CT With Cognitive Impairment Profile and Severity.

PURPOSE: To assess the correlation between profile and severity deterioration in the neuropsychological assessment and the most affected regions in amyloid PET semiquantification. The influence of vascular risk and other potential confounding factors was also evaluated. METHODS: A retrospective, observational, and multicenter study including all patients referred for amyloid PET in daily practice was conducted. Patients underwent neuropsychological assessment, and cognitive decline severity and domain(s) affected were recorded. The patients were grouped according to cognitive impairment (CI) profile and severity: (A) no CI, single-domain amnestic CI, multiple-domain amnestic CI, and nonamnestic CI; and (B) mild CI, moderate and severe dementia. An adapted Framingham Stroke Risk Profile was calculated for each individual. Depression and parkinsonism were also recorded. Standardized quantitative analysis software was used to obtain standardized uptake value ratio (SUVR) values from PET/CT images. The corresponding associations were assessed with the most appropriate statistical tests. RESULTS: One hundred twenty-nine patients were included (62 men, 67 women; 64.67 ± 7.47 years old). Significant differences in global and regional amyloid load were exclusively found in women between non-CI and moderate dementia ( P = 0.006, for total-cerebellum SUVR). Posterior and anterior cingulates and prefrontal cortex best represented CI severity ( P = 0.003, 0.006, and 0.006, respectively). No relationship between the CI profile and the regional amyloid load was shown. A significantly high positive correlation was found between age and vascular risk and between these variables and amyloid load in nearly all regions, especially in women with moderate dementia. CONCLUSION: Semiquantitative analysis of amyloid PET by SUVR values revealed a significant correlation between amyloid burden and CI severity, although only in women.

Increasing the confidence of 18F-Florbetaben PET interpretations: Machine learning quantitative approximation.

AIM: To assess the added value of semiquantitative parameters on the visual assessment and to study the patterns of 18F-Florbetaben brain deposition. MATERIALS AND METHODS: Retrospective analysis of multicenter study performed in patients with mild cognitive impairment or dementia of uncertain origin. 18F-Florbetaben PET scans were visually interpreted by two experienced observers, analyzing target regions in order to calculate the interobserver agreement. Semiquantification of all cortical regions with respect to three reference regions was performed to obtain standardized uptake value ratios (SUVRs). The ability of SUVRs to predict the visual evaluation, the possibility of preferential radiotracer deposition in some target regions and interhemisphere differences were analyzed. RESULTS: 135 patients were evaluated. In the visual assessment, 72 were classified as positive. Interobserver agreement was excellent. All SUVRs were significantly higher in positive PET scans than in negative ones. Prefrontal area and posterior cingulate were the cortical regions with the best correlations with the visual evaluation, followed by the composite region. Using ROC analysis, the SUVRs obtained in same target locations showed the best diagnostic performance. CONCLUSIONS: The derived information from target regions seems to help the visual classification, based on a preferential amyloid ß deposit, allowing machine learning. The amyloid ß deposit, although diffuse in all cortical regions, seems not to be uniform and symmetric.

Prognostic Potential of Postoperative 18F-Fluorocholine PET/CT in Patients With High-Grade Glioma. Clinical Validation of FuMeGA Postoperative PET Criteria.

OBJECTIVE: The aim of this study was to assess the prognostic performance of postoperative 18F-fluorocholine PET/CT in patients with high-grade glioma (HGG). METHODS: Patients with HGG who underwent preoperative and postoperative 18F-fluorocholine PET/CT were prospectively enrolled in the study. Postoperative MRI was classified as complete versus incomplete resection. Postoperative 18F-fluorocholine PET/CT was classified as negative (complete) or positive for metabolic residual tumor (incomplete resection) using a 5-point score system. The correlation of positive locations on PET/CT with the sites of subsequent tumor recurrence was evaluated. The concordance of postoperative imaging techniques (Cohen κ) and their relation with progression-free survival and overall survival were assessed using Kaplan-Meier method and Cox regression analysis. RESULTS: Fifty-one studies, belonging to 47 patients, were assessed. Four patients underwent 2 postoperative 18F-fluorocholine PET/CT scans as they needed a second tumor resection for recurrence. In the follow-up, 42 patients progressed, and 37 died. Concordance between postoperative PET/CT and MRI assessment was poor. Resection grade on MRI did not show any significant association with prognosis. In multivariate analysis, only age and postoperative PET/CT showed significant association with progression-free survival (hazard ratio [HR], 1.03 [1.01-1.06, P = 0.006] and 1.88 [0.96-3.71, P = 0.067], respectively) and overall survival (HR, 1.04 [1.01-1.07, P = 0.004] and 2.63 [1.22-5.68, P = 0.014], respectively). Postoperative positive 18F-fluorocholine PET/CT locations correlated with the sites of subsequent tumor recurrence in 81.82% of cases. CONCLUSION: Postoperative 18F-fluorocholine PET/CT seems superior to postoperative MRI in the outcome prediction of patients with HGG, outperforming it in the identification of the most probable location of tumor recurrence.

Estudio prospectivo comparativo de dos métodos de cálculo individual de la actividad de 131I en el tratamiento del hipertiroidismo / A prospective comparative study of two methods of individual calculation of 131I activity in the treatment of hyperthyroidism

OBJETIVO: El radioyodo (131I) constituye una modalidad establecida de tratamiento definitivo del hipertiroidismo. A pesar de la vasta experiencia existente, persisten varios aspectos por clarificar, como qué tipo de dosis emplear, ¿fijas o calculadas? El objetivo del estudio fue determinar si se podría mejorar la eficacia de este tratamiento implementando un método simple de cálculo dosimétrico que incluyera la estimación ecográfica del volumen tiroideo y una medida única de captación de 131I (24h). MÉTODOS: Diseñamos un estudio prospectivo de no inferioridad comparando entre dos modalidades de cálculo de la actividad de radioyodo: el método de dosis «semifijas» (A) y el de dosis «calculadas» (B). El primero consistió en escaladas de actividad (peldaños de 185MBq) teniendo en cuenta: etiología del hipertiroidismo, captación de 131I y objetivo terapéutico. El segundo se basó en el concepto de «compromiso dosimétrico», considerando como únicos factores la captación y el volumen tiroideos, empleando una vida media estándar de 5,5días. La dosis absorbida diana fue 150Gy, aunque tras un análisis preliminar (100 primeros casos) se aumentó a 200Gy en los bocios difusos tóxicos (BDT). RESULTADOS: Se incluyeron 212 pacientes. El métodoB resultó al menos igual de eficaz en cuanto al resultado final y funcional, con tendencia a más éxitos y menos hipotiroidismo. Además, las actividades administradas fueron significativamente menores. CONCLUSIÓN: En la terapia con radioyodo del hipertiroidismo se pudo implementar un método dosimétrico sencillo que proporcionó resultados al menos iguales a los de un método basado en dosis fijas, con actividades administradas inferiores

OBJECTIVE: Radioiodine (131I) is an established modality of definitive treatment of hyperthyroidism. In spite of the vast experience available, there are still several aspects to be clarified, such as whether fixed or calculated doses should be used. The aim of this study was to assess whether efficacy of this treatment could be improved by implementing a simple dosimetric calculation method including ultrasonographic estimation of thyroid volume and a single measurement of 24-hour 131I thyroid uptake. METHODS: A prospective non-inferiority study was designed to compare two procedures to calculate radioiodine activity: the «semi-fixed» dose method (A), and the «calculated» dose method (B). The first consisted of activity escalation (185MBq steps) based on etiology of hyperthyroidism, 131I uptake, and treatment objective. The second method was based on the «dosimetric compromise» concept, considering 24-hour uptake and thyroid volume as the only factors and using a standard half-life of 5.5 days. The target absorbed dose was 150Gy, but after a preliminary analysis (first 100 cases) it was increased to 200Gy in diffuse toxic goiters (DTGs). RESULTS: A total of 212 patients were included. MethodB was at least as effective in terms of final and functional outcome, with a trend to more success and less hypothyroidism. In addition, activities administered were significantly lower. CONCLUSION: In radioiodine therapy of hyperthyroidism, a simple dosimetric method that provided results at least equal to those of a fixed dose-based method, with lower administered activities, could be implemented

Metabolic targeting can improve the efficiency of brain tumor biopsies.

Brain tumors comprise a heterogeneous group of diseases, featuring different biology, prognosis, and treatment. The most known forms are malignant gliomas and metastases. Brain biopsy is a recognized technique in the management of intracranial space-occupying lesions and tumors in particular. Tumor heterogeneity of malignant brain lesions has been described and can lead to significant sampling errors in stereotactic biopsy. Different methods have been used to perform biopsies, including biopsy guided by CT or RMI, echoguided or stereotactic. The choice of the target with the help of PET and MRI with spectroscopy allows one to identify metabolically more active areas of the tumor, and in this way reduce the rate of negative results.

A prospective comparative study of two methods of individual calculation of 131I activity in the treatment of hyperthyroidism. / Estudio prospectivo comparativo de dos métodos de cálculo individual de la actividad de 131I en el tratamiento del hipertiroidismo.

OBJECTIVE: Radioiodine (131I) is an established modality of definitive treatment of hyperthyroidism. In spite of the vast experience available, there are still several aspects to be clarified, such as whether fixed or calculated doses should be used. The aim of this study was to assess whether efficacy of this treatment could be improved by implementing a simple dosimetric calculation method including ultrasonographic estimation of thyroid volume and a single measurement of 24-hour 131I thyroid uptake. METHODS: A prospective non-inferiority study was designed to compare two procedures to calculate radioiodine activity: the «semi-fixed¼ dose method (A), and the «calculated¼ dose method (B). The first consisted of activity escalation (185MBq steps) based on etiology of hyperthyroidism, 131I uptake, and treatment objective. The second method was based on the «dosimetric compromise¼ concept, considering 24-hour uptake and thyroid volume as the only factors and using a standard half-life of 5.5 days. The target absorbed dose was 150Gy, but after a preliminary analysis (first 100 cases) it was increased to 200Gy in diffuse toxic goiters (DTGs). RESULTS: A total of 212 patients were included. MethodB was at least as effective in terms of final and functional outcome, with a trend to more success and less hypothyroidism. In addition, activities administered were significantly lower. CONCLUSION: In radioiodine therapy of hyperthyroidism, a simple dosimetric method that provided results at least equal to those of a fixed dose-based method, with lower administered activities, could be implemented.

18F-choline PET/computed tomography and clinical parameters in the detection of significant prostate cancer in patients with increased prostate-specific antigen levels and previous negative biopsies.

OBJECTIVES: The aim of this study is to assess the value of the F-choline PET/computed tomography (CT) in predicting significant prostate cancer (sPCa) in patients with persistently increased prostate-specific antigen (PSA) levels and previous negative biopsies. To study the possible predictive added value of F-choline PET/CT to clinical variables and biomarkers derived from PSA in detecting sPCa. METHODS: We evaluated patients who underwent F-choline PET/CT because of ongoing suspicion of prostate cancer (PCa) due to elevated PSA levels (4-20 ng/mL) and at least one previous negative or no conclusive prostate biopsy for PCa. Age, PSA, free PSA, free/total PSA ratio, PSA velocity, PSA doubling time, PSA density and score risk were obtained. F-choline PET/CT was classified as negative/positive (PET-categorical). Additionally, we subclassified F-choline PET/CT according to the radiotracer uptake patterns (PET-pattern). The reference standard was the histological confirmation. Accuracy of PET/CT was evaluated. Univariate and multivariate logistic regression analyses were performed for metabolic and clinical variables. RESULTS: A total of 78 patients were included in our study, 23 had PCa (15 with sPCa). The PET pattern showed the highest accuracy and was the most powerful predictor of sPCa. In this research, the prediction of sPCa was improved combining PET pattern and score risk. CONCLUSION: F-choline PET/CT is a potential tool for predicting sPCa in patients with persistently increased PSA levels and previous negative biopsies, and also it could improve the performance of score risk in predicting sPCa.

FuMeGA Criteria for Visual Assessment of Postoperative 18F-Fluorocholine PET in Patients With Glioma.

Postoperative assessment is crucial in the imaging follow-up and prognosis in patients with glioma. Whereas grade of resection is defined attending to the gadolinium enhancement in early postoperative MRI, no metabolical criteria exist for postoperative PET interpretation. Based on our prospective and multicenter FuMeGA (Functional and Metabolic Glioma Analysis) ongoing study, we propose criteria for the visual interpretation of F-fluorocholine PET scans in patients undergoing brain tumor resection. The different imaging characteristics between MRI and PET may explain the discordances regarding to the postresection status with both techniques.

18F-Fluorocholine PET/CT in the Prediction of Molecular Subtypes and Prognosis for Gliomas.

AIM: To study the association of metabolic features of F-fluorocholine in gliomas with histopathological and molecular parameters, progression-free survival (PFS) and overall survival (OS). METHODS: Prospective multicenter and nonrandomized study (Functional and Metabolic Glioma Analysis). Patients underwent a basal F-fluorocholine PET/CT and were included after histological confirmation of glioma. Histological and molecular profile was assessed: grade, Ki-67, isocitrate dehydrogenase status and 1p/19q codeletion. Patients underwent standard treatment after surgery or biopsy, depending on their clinical situation. Overall survival and PFS were obtained after follow-up. After tumor segmentation of PET images, SUV and volume-based variables, sphericity, surface, coefficient of variation, and multilesionality were obtained. Relations of metabolic variables with histological, molecular profile and prognosis were evaluated using Pearson χ and t test. Receiver operator caracteristic curves were used to obtain the cutoff of PET variables. Survival analysis was performed using Kaplan-Meier and Cox regression analysis. RESULTS: Forty-five patients were assessed; 38 were diagnosed as having high-grade gliomas. Significant differences of SUV-based variables with isocitrate dehydrogenase status, tumor grade, and Ki-67 were found. Tumor grade, Ki-67, SUVmax, and SUVmean were related to progression. Kaplan-Meier analysis revealed significant associations of SUVmax, SUVmean, and multilesionaly with OS and PFS. SUVmean, sphericity, and multilesionality were independent predictors of OS and PFS in Cox regression analysis. CONCLUSIONS: Metabolic information obtained from F-fluorocholine PET of patients with glioma may be useful in the prediction of tumor biology and patient prognosis.

Diverse Behavior in 18F-Fluorocholine PET/CT of Brain Tumors in Patients With Neurofibromatosis Type 1.

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder that causes CNS tumors in around 20% of patients, being pilocytic astrocytomas (PA), and particularly optic pathway gliomas (OPG), the most common. We present three cases of NF1 patients referred for F-fluorocholine PET/CT because of suspected glioma in the setting of ongoing FUMEGA (Functional and Metabolic Glioma Analysis) trial. One case turned out to be a WHO grade I ganglioglioma; the second was a high grade glioma; and the last one (negative in PET) a probable low-grade glioma.

Ischemic Complications After High-Grade Glioma Resection Could Interfere With Residual Tumor Detection With 18F-Fluorocholine PET/CT.

Ischemic complications after resection of high-grade glioma are frequent and may constitute potential cause of false-positive results in postsurgical evaluation using F-fluorocholine PET/CT. On the other hand, hypoxia caused by ischemia promotes invasive glioma growth. We present 3 cases of patients with different grades of ischemic injury after resection of high-grade glioma. The combined interpretation of diffusion-weighted imaging and apparent diffusion coefficient map on MRI, in this clinical setting, is mandatory to avoid PET/CT misinterpretations.

Low-Dose Radioiodine Ablation in Patients with Low-Risk Differentiated Thyroid Cancer.

AIM: Based on the response criteria of the 2015 American Thyroid Associations guidelines, our objectives were to -determine the response rate when using a low dose of -131-I GBq in patients with low-risk differentiated thyroid cancer (LRDTC) and the influence of clinical and analytical variables on the prediction of complete response. METHODS: We performed a multicentre and longitudinal study, including patients who were operated for LRDTC and who underwent radioiodine remnant ablation with a low-dose of 131-I. All patients were assessed at 6-12 months, and their status was classified as complete (excellent response) or incomplete response (structural incomplete, biochemical incomplete or indeterminate response). Various factors including age, gender, histology, tumour focality and size, stage, time from surgery to treatment, type of thyroid-stimulating hormone (TSH) stimulation, preablation serum thyroglobulin (pTg), antiTg antibodies (pAntiTgAb) and TSH (pTSH) levels were also analysed in order to predict the complete response rate. RESULTS: Of 108 patients, 79.6$ achieved complete response and the remaining showed incomplete response (2.9, 5.5 and 12$ due to biochemical incomplete, structural incomplete and indeterminate response respectively). Six patients received a new dose of 131-I. Tumour size and pAntiTgAb were the only factors related to therapeutic response (p = 0.03 and p < 0.01, respectively). However, pAntiTgAb was the only independent factor related to complete -response. Patients with complete response showed lower pTg than those with incomplete response (5.1 ± 12.9 vs. 11.2 ± 25 ng/mL) although without statistical significance (p = 0.14). There was no significant difference in the response rate depending on the thyrotropin stimulation methods. CONCLUSIONS: A low dose of 131-I was sufficient for reaching a complete response at 6-12 months of follow-up in the majority of patients with LRDTC. Tumour size and pAntiTgAb variables were related to therapeutic response.

Value of [18F]FDG-PET/CT and CA125, serum levels and kinetic parameters, in early detection of ovarian cancer recurrence: Influence of histological subtypes and tumor stages.

To assess the diagnostic accuracy of CA125, its kinetic values and positron emission tomography/computed tomography with 2-deoxy-2-[F]fluoro-D-glucose ([F]FDG-PET/CT), in relation with tumor characteristics for suspected recurrence of ovarian cancer. To evaluate the performance of CA125-related parameters as a selection criteria to perform a [F]FDG-PET/CT.A retrospective analysis of 69 [F]FDG-PET/CT for suspected recurrence of ovarian cancer was performed. All patients had 2 measurements of CA125, before PET/CT, to calculate kinetic values, as CA125vel (CA125vel = [CA125a - CA125b]/time) and CA125dt (CA125dt = [log2 × time]/[logCA125a - CA125b]). Maximum standard uptake value (SUVmax) was calculated. The diagnostic accuracy was calculated for all the variables and the optimal cut-off value of each of them by the receiver-operating characteristics (ROC) analysis. All the tests were compared with tumor characteristics and clinical-radiological evolution during follow-up of at least 6 months.Fifty-five cases were diagnosed of recurrence (11 with CA125 <35 U/mL), while 14 showed no disease (11 with CA125 < 35 U/mL). All of them were correctly cataloged by PET/CT. CA125, CA125vel, and SUVmax showed higher levels in recurrent patients (mean 129.54 U/mL, 24.58 U/mL per mo, and 8.69 g/mL, respectively) than in nonrecurrent (mean 20.35 U/mL, 0.60 U/mL per mo, and 0.64 g/mL, respectively). No statistical differences in CA125dt were found. Patients with recurrence of high-grade serous carcinoma (HGSC) showed higher CA125 and CA125vel, without differences in the rest of subtypes and International Federation of Gynecology and Obstetrics stages. The ROC analyses for CA125, CA125vel, and CA125dt showed an area under the curve (AUC) of 0.873 (95% confidence interval [CI] 0.77-0.969), 0.903 (95% CI 0.813-0.994), and 0.727 (95% CI 0.542-0.913), respectively, with an optimal cut-off point of 23.95 U/mL, 4.49 U/mL per mo, and 3.36 months, respectively, while for the SUVmax the AUC was of 0.982 (95% CI 0.948-1.000), and the cut-off point of 2. Multivariate regression analysis identified CA125 and CA125vel as predictors of recurrence.[F]FDG-PET/CT is more accurate than the parameters obtained from the CA125 to detect early recurrence. CA125vel is the most suitable parameter, mainly in HGSC. Levels of CA125vel ≥ 4.49 U/mL per mo facilitate earlier detection by the execution of a [F]FDG-PET/CT. The calculation of these parameters is independent of tumor stage at diagnosis.

Do clinical and laboratory variables have any impact on the diagnostic performance of 18F-FDG PET/CT in patients with fever of unknown origin?

OBJECTIVE: To assess the influence of clinical features and laboratory test results on the determination of fever of unknown origin (FUO) by means of 18F-FDG PET/CT. METHODS: Retrospective and longitudinal analysis, including all the PET/CT studies requested for FUO. Reference standard was established by serology, cultures or biopsy with other laboratory tests or clinical follow-up when necessary. Clinical variables, inflammation markers, protein analysis, serology and culture results close to the PET scan were obtained. The final diagnosis was classified into three groups attending to the etiology; group 1: infection or neoplasm, group 2: vasculitis, autoimmune disease or non-infectious inflammatory disease and group 3: auto-limited fever or persistent fever without diagnosis. PET/CT scans were classified as positive or negative and helpful or not in the diagnosis of the fever origin. The effect of clinical features and laboratory variables on the PET/CT results was analyzed. RESULTS: Sixty-seven patients were evaluated. The final diagnosis was: Group 1 (25), Group 2 (20) and Group 3 (22). 89.6% of patients had a positive inflammation marker, 28.4% proteinogram alterations and 20.9% positive cultures. PET/CT was positive in 52/67 patients. PET/CT helped in the establishment of the fever origin in 35 cases and was especially helpful in groups 1 and 2. Sensitivity, specificity and accuracy of PET/CT were: 84, 31 and 61%. PET results shown significant relations with the final diagnosis (p = 0.035) and culture results (p = 0.037). No significant relations were observed with the rest of clinical or laboratory variables. CONCLUSIONS: 18F-FDG PET/CT had a high sensitivity but a low specificity in the diagnosis of the fever origin, probably due to the high rate of diffuse and auto-limited aetiologies. Patients who are most likely to benefit from the PET/CT study would be those with several positive inflammation markers, reflecting a higher pre-test probability of active disease.

Prognostic Role of Early and End-of-Neoadjuvant Treatment 18F-FDG PET/CT in Patients With Breast Cancer.

AIM: To determine the use of early and final treatment F-FDG PET/CT in the prediction of response to neoadjuvant chemotherapy (NAC) and its role in the prognosis of patients with locally advanced breast cancer (LABC). METHODS: One hundred thirty-two patients underwent a baseline FDG PET/CT (PET-1) after the second course of chemotherapy (PET-2) and after the last course (PET-3). Breast tumors were categorized into molecular phenotypes and risk categories according to the biological prognostic factors obtained by immunohistochemistry. PET/CT scans were semiquantitatively evaluated, obtaining the Δ% SUV1-2 and SUV1-3 in primary tumor and axillary lymph nodes to establish response groups attending to EORTC criteria. Moreover, a binary assessment was obtained classifying the studies as positive or negative. Histopathological response was obtained in breast and lymph node specimens. Overall survival (OS) and disease-free survival (DFS) were obtained after the follow-up. ROC analysis was performed to determine a cutoff value of Δ% SUV1-2 and SUV1-3 for the prediction of response and prognosis. Relations between phenotypes, metabolic behavior, final histopathological response, OS, and DFS were evaluated. RESULTS: In binary analysis, only PET-3 was able to predict histopathological response in lymph nodes. The cutoff values of %Δ SUV1-2 and %Δ SUV1-3 with the best sensitivity and specificity in the prediction of response in breast tumor were 62% (Se: 70% and Sp: 69%) and 84% (Se: 70% and Sp: 88%). A %ΔSUV1-3 of 74% in breast tumor was a predictor of DFS (AUC = 0.647; P = 0.037, Se: 52% and Sp: 66%). Kaplan-Meier analysis revealed significant relations between the binary lymph node assessment of PET-3 with OS (P = 0.016, χ = 5.78) and DFS (P = 0.003, χ = 9.10). CONCLUSIONS: End-of-treatment F-FDG PET/CT was a predictor of lymph node response and prognosis. Most of metabolic response variables related to histopathological response showed association with the prognosis.