Acute Brain Stroke Evolution Detected by 18F-FDG PET/CT and MRI Justifies the Discordance of Lesions in a Patient With Lymphoproliferative Syndrome.

ABSTRACT: A 50-year-old man with angioimmunoblastic T-cell lymphoma in complete response to treatment presented new hypermetabolic brain lesions on 18F-FDG PET/CT suggestive of malignancy. These findings were correlated by MRI that showed cortical-subcortical peripheral lesions typical of acute ischemic infarction. A restaging 18F-FDG PET/CT showed that hypermetabolic lesions were replaced by ametabolic areas, supporting chronic infarction. Early ischemia presents transitory FDG increase. Brain lymphomas are highly FDG avid and difficult to differentiate from acute cerebral infarction. In view of the discordance of abnormal areas of intracranial uptake on PET FDG, MRI confirmation is required to avoid misinterpretation.

Miositis osificante: gammagrafía ósea y tomografía por emisión de positrones/tomografía computarizada con 18F-desoxiglucosa / Imaging in myositis ossificans: Bone scintigraphy and 18F-fluorodeoxyglucose positron emission tomography/computed tomography

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18F-FDG PET/TC en la estadificación inicial de pacientes con rabdomiosarcoma alveolar / 18F-FDG PET/CT as staging of alveolar rhabdomyosarcoma

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Diagnostic utility of PET/CT with 18F-DOPA and 18F-FDG in persistent or recurrent medullary thyroid carcinoma: the importance of calcitonin and carcinoembryonic antigen cutoff.

PURPOSE: This study sought to evaluate and compare the utility of 18-F-fluorodihydroxyphenylalanine (18F-DOPA) and 18-F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for identification of lesions in patients with recurrent medullary thyroid carcinoma (MTC). In addition, we analyzed the correlation between the calcitonin (Ct), carcinoembryonic antigen (CEA) levels, each doubling time (DT), and PET positivity. We evaluated the reliability of the 150 pg/mL Ct cutoff set by the American Thyroid Association guidelines for further imaging (including 18F-DOPA PET/CT). METHODS: We prospectively recruited 18 patients with recurrent MTC, identified by elevation of Ct or CEA. Each patient underwent a 18F-FDG PET/CT and a 18F-DOPA PET/CT. RESULTS: Abnormal uptakes were detected with 18F-DOPA (n=12) and 18F-FDG (n=9), (sensitivity of 66.7% vs. 50%; p<0.01). Twenty-eight lesions were detected with 18F-DOPA vs. 16 lesions with 18F-FDG (1.56±1.5 vs. 0.89±1.18 lesions per patient; p=0.01). None of our patients showed additional lesions with 18F-FDG in comparison to 18F-DOPA. Patient-based detection rate increased significantly with Ct levels ≥150 pg/mL vs. Ct<150 pg/mL for both 18F-DOPA (sensitivity 90.9% vs. 28.6%; p=0.013) and 18F-FDG PET/CT (sensitivity 72.7% vs. 14.3%; p=0.025). Using a CEA cutoff of ≥5 ng/mL, detection rates of 18F-DOPA and 18F-FDG PET/CT were 81.1% and 72.7%, respectively. No correlation between Ct-DT or CEA-DT and PET positivity was found. Histological confirmation was obtained in eight patients. CONCLUSIONS: 18F-DOPA PET/CT appears to be superior to 18F-FDG PET/CT in detecting and locating lesions in patients with recurrent MTC. This technique tends to be especially useful in patients with negative results in other imaging modalities and Ct≥150 pg/mL or CEA≥5 ng/mL.

18F-FDG PET/CT de cuerpo completo en pacientes con mieloma múltiple / Whole-body 18F-FDG PET/CT in patients with multiple myeloma

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Utilidad de la imagen híbrida tomografía por emisión de fotón único/tomografía computarizada con 99mTc-hidroximetileno-difosfonato en el estudio del síndrome del túnel tarsiano / Usefulness of 99mTc-hydroxymethylene-diphosphonate single photon emission computed tomography/computed tomography hybrid imaging in the study of tarsal tunnel syndrome

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Utilidad de la tomografía por emisión de positrones con 18F-Fluorodesoxiglucosa combinada con tomografía computarizada en la orientación diagnóstica de la fiebre de origen desconocido / Usefulness of 18FDG PET-CT scan as a diagnostic tool of fever of unknown origin

Fundamento y objetivo: La fiebre de origen desconocido (FOD) se define clásicamente como fiebre de más de 3 semanas, con temperatura superior a 38,3 °C en varias ocasiones y sin diagnóstico definitivo tras una semana de hospitalización. Determinar su etiología es fundamental para establecer un tratamiento adecuado del paciente. Nuestro objetivo es valorar la utilidad de la tomografía por emisión de positrones con 18F-Fluorodesoxiglucosa (18F-FDG) combinada con tomografía computarizada (PET/TC) con fluorodesoxiglucosa marcada con flúor 18 (18F-FDG) en la orientación diagnóstica de la FOD. Material y método: Estudio observacional retrospectivo de exploraciones PET/TC realizadas a 30 pacientes consecutivos con FOD entre marzo de 2010 y septiembre de 2013. El diagnóstico definitivo se alcanzó en 26/30 pacientes (86,67%): 15 con confirmación histológica, microbiológica en un caso y con seguimiento clinicorradiológico (media de 16,38 meses) en 10 pacientes. Resultados: Un total de 23 estudios fueron positivos: 10 con etiología tumoral, 8 inflamatoria, 4 infecciosa y uno miscelánea (100% verdaderos positivos). La PET/TC mostró una eficacia en el enfoque diagnóstico del 90,00%, una sensibilidad del 88,46% (intervalo de confianza del 95% [IC 95%] 76-101), una especificidad del 100,00% (IC 95% 100-100), un valor predictivo positivo del 100,00% (IC 95% 100-100) y un valor predictivo negativo del 57,14% (IC 95% 20-91). Conclusiones: La 18F-FDG PET/TC ha demostrado presentar una elevada sensibilidad y especificidad en el diagnóstico etiológico de la FOD, aportando una información morfofuncional valiosa, especialmente en la localización del lugar óptimo para la toma de biopsias (AU)

Background and objective: Classic fever of unknown origin (FUO) is defined as the presence of fever greater than 38.3 °C of at least 3 weeks with an uncertain diagnosis. Identification of the etiology is crucial in guiding further diagnostic procedures and subsequent patient management. The aim of this study was to evaluate the role of fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography combined with computed tomography (PET/CT) in the diagnostic orientation of FUO. Material and method: An observational retrospective study was performed, including 30 consecutive patients who had been studied between March 2010 and September 2013. Twenty-six out of 30 patients (86.67%) had a definitive diagnosis after pathologic confirmation in 15 cases, microbiological findings in one patient and clinical and radiological follow-up in 10 patients (mean: 16.38 months). Results: Among the positive scans, malignancy (n = 10), inflammatory (n = 8), infectious (n = 4) and miscellaneous causes (n = 1) were identified. 18F-FDG PET/CT had a diagnostic accuracy of 90.00%, sensitivity of 88.46% (95% confidence interval [95% CI] 76-101), specificity of 100.00% (95% CI 100-100), positive predictive values of 100.00% (95% CI100-100) and negative predictive value of 57.14% (95% CI 20-91). Conclusions: 18F-FDG PET/CT provided useful for the etiologic diagnosis of FUO, with high sensitivity and specificity.18F-FDG PET/CT has an incremental morphological and functional value, especially indicating the best biopsy site (AU)

18F-FDG PET/CT in Extranodal Burkitt Lymphoma.

Burkitt lymphoma (BL) is a poorly differentiated non-Hodgkin B-cell lymphoma, more frequent in children than in adults. The extranodal debut of the disease is rare. We report a 43-year-old male patient with history of dyspnea. Burkitt lymphoma diagnosis was reached after biopsy of a pleural lesion. An initial staging F-FDG-PET/CT revealed large high-uptake lymphatic clusters in mediastinum, lung hilum, and extranodal involvement in pleura, pericardium, periphery of liver and spleen, all the omentum and peritoneum down to the pelvic floor, and bone marrow infiltration.

Role of 18F-FDG-PET/CT in the management of Burkitt lymphoma.

UNLABELLED: Burkitt lymphoma (BL) is highly FDG-avid even though its usefulness in the management of these patients is still controversial. AIM: We analyzed the role of positron emission tomography/computerized tomography (PET/CT) in staging newly diagnosed patients with BL and evaluating disease after first-line chemotherapy. METHODS: Fifty-two PET/CTs were performed in 32 patients (20 at diagnosis, 27 after treatment, five to monitor residual disease). Involved areas were retrospectively compared with those observed in contrast-enhanced CT. RESULTS: Discrepancies were found in 64.7% of patients for whom results of both tests at diagnosis were available (n = 17), most of them involving extranodal sites. Regarding response assessment, discrepancies were observed in 38% of patients with both tests (5/13): residual masses detected by CT with negative PET/CT. Of 27 patients with post-treatment PET/CT, 22 were in complete remission whereas one true-positive and four false-positive lesions (two nodal and two extranodal) were detected. With a median follow-up of 27 months, 22 patients with negative PET/CT did not relapse. Thus, negative predictive value (NPV) was 100%. With respect to positive predictive value (PPV), one of five patients with positive assays after treatment died due to progression while the remaining four had false-positive lesions. Nevertheless, for these four patients, mean SUVmax at nodal sites was 4.1 vs. 14.9 at diagnosis, while mean SUVmax at extranodal sites was 3.8 vs. 12.1. Thus, with a cutoff value for SUVmax < 66% of that observed at diagnosis, PPV was also 100%. CONCLUSION: More accurate staging can be achieved using PET/CT. NPV reaches 100%, and using a ΔSUV < 66%, a high PPV is also observed.

Role of 18F-FDG-PET/CT in the management of marginal zone B cell lymphoma.

The use of PET in patients with marginal zone B cell lymphoma (MZL) is controversial because of variability of fluorodeoxyglucose (FDG) avidity. We analyzed 40 PET/CT in 25 consecutive patients to compare its performance with CT at staging and as a first-line response assessment. Sensitivity of PET/CT and CT was 96 and 76%. Mean standard uptake value was 6.1, 6.9 and 3.4 (p = 0.3) in nodal, extranodal and splenic subtypes, respectively. Of 17 patients (extranodal: n = 9; nodal: n = 6; splenic subtype: n = 2) with both imaging tests available at diagnosis, 8 (47%) had more involved areas with PET/CT than with CT, 75% of which were extranodal lesions. PET/CT resulted in upstaging of five patients although treatment of only two of them was changed. Responses of 15 patients with post-treatment PET/CT were the following: 9 negative and 6 positive of which 3 were isolated residual lesions. Progression was documented in two of these three patients. Response was also assessed by CT in 11 patients. Discrepancies were found in three: Two were in complete remission by CT while PET/CT detected localized residual disease; another patient was in partial remission by CT, whereas PET/CT showed only one positive lesion. Two of these three patients relapsed. Patients with negative post-treatment PET/CT did not relapse. With a median follow-up of 50 months (10-152 months), 3-year overall survival was 100 and 80% for patients with negative and positive post-treatment PET/CT (p = 0.2). Three-year disease-free survival was 86%; the negative predictive value (NPV) was 100%, and the positive predictive value (PPV) was 83.3%. Although a larger number of patients will be required to further confirm these data, we can conclude that PET/CT is a useful imaging tool for both staging and response assessment in patients with nodal and extranodal MZL as a result of its high sensitivity, NPV and PPV.

[Usefulness of (18)FDG PET-CT scan as a diagnostic tool of fever of unknown origin]. / Utilidad de la tomografía por emisión de positrones con (18)F-Fluorodesoxiglucosa combinada con tomografía computarizada en la orientación diagnóstica de la fiebre de origen desconocido.

BACKGROUND AND OBJECTIVE: Classic fever of unknown origin (FUO) is defined as the presence of fever greater than 38.3°C of at least 3 weeks with an uncertain diagnosis. Identification of the etiology is crucial in guiding further diagnostic procedures and subsequent patient management. The aim of this study was to evaluate the role of fluorine-18 fluorodeoxyglucose ((18)F-FDG) positron emission tomography combined with computed tomography (PET/CT) in the diagnostic orientation of FUO. MATERIAL AND METHOD: An observational retrospective study was performed, including 30 consecutive patients who had been studied between March 2010 and September 2013. Twenty-six out of 30 patients (86.67%) had a definitive diagnosis after pathologic confirmation in 15 cases, microbiological findings in one patient and clinical and radiological follow-up in 10 patients (mean: 16.38 months). RESULTS: Among the positive scans, malignancy (n=10), inflammatory (n=8), infectious (n=4) and miscellaneous causes (n=1) were identified. (18)F-FDG PET/CT had a diagnostic accuracy of 90.00%, sensitivity of 88.46% (95% confidence interval [95% CI] 76-101), specificity of 100.00% (95% CI 100-100), positive predictive values of 100.00% (95% CI100-100) and negative predictive value of 57.14% (95% CI 20-91). CONCLUSIONS: (18)F-FDG PET/CT provided useful for the etiologic diagnosis of FUO, with high sensitivity and specificity. (18)F-FDG PET/CT has an incremental morphological and functional value, especially indicating the best biopsy site.

Enfermedad de Erdheim-Chester / Erdheim-Chester disease

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