Update on the diagnosis of encephalitis.

Autoimmune encephalitis are brain inflammatory processes that are classified into two main groups according to the underlying pathogenic mechanism: antibodies to intracellular antigens (paraneoplastic) and antibodies to extracellular or neuronal surface antigens. The clinical manifestations of autoimmune encephalitis are very varied and non-specific. Complementary tests included in its clinical diagnosis include determination of antibodies in serum or cerebrospinal fluid and magnetic resonance imaging (MRI). MRI may show characteristic patterns such as mesial temporal involvement, although in some cases it may be normal or non-specific. 18F-Fluorodeoxyglucose PET/CT (18F-FDG PET/CT) imaging may be helpful in cases of paraneoplastic autoimmune encephalitis to find the primary tumor. In autoimmune encephalitis mediated by antibodies to extracellular antigens, 18F-FDG PET/CT shows distinctive patterns that can aid clinical diagnosis. This continuing education aims to present in a clear and easy-to-understand way, the clinical features of autoimmune encephalitis, the difficulties in clinical diagnosis and the patterns seen on MRI and 18F-FDG PET/CT.

Regional disparity of HIV incidence and prevalence among men who have sex with men.

BACKGROUND: HIV incidence can be estimated with cross-sectional studies using clinical, serological, and molecular data. Worldwide, HIV incidence data in only men who have sex with men (MSM) are scarce and principally focus on those with healthcare or under treatment. However, better estimates can be obtained through studies with national representativeness. The objective was to estimate the prevalence, incidence, and factors associated with acquiring HIV in a national sample of MSM who attend meeting places, considering geographical regions. METHODS: A nationally representative survey of MSM attending meeting places was performed in Mexico. Participants answered a questionnaire, and a dried blood spot (DBS) was collected. Samples were classified as recent infections using an algorithm with HIV status, antiretroviral therapy, and the result of BED-EIA assay. Parameters were analysed considering regions and demographic and sexual behaviour characteristics. RESULTS: The national HIV prevalence was 17.4% with regional differences; the highest prevalence (20.7%) was found in Mexico City, and the lowest prevalence was found in the West region (11.5%). The incidence was 9.4 per 100 p/y, with regional values from 6.2 to 13.2 for the Northeast and the Centre regions, respectively. Age, age at sexual debut, low wealth index, and rewarded sex were associated with HIV prevalence. Centre region, use of private clinics as health services, and having sex exclusively with men were associated with recent HIV infections. CONCLUSIONS: The incidence and prevalence showed regional differences, suggesting a difference in the dynamics of HIV transmission; some regions have a greater case accumulation, and others have a greater rate of new infections. Understanding this dynamic will allow developing health programs focused on HIV prevention or treating people already living with HIV.

Cost-effectiveness analysis of a multidisciplinary health-care model for patients with type-2 diabetes implemented in the public sector in Mexico: A quasi-experimental, retrospective evaluation.

OBJECTIVE: In 2007, the Ministry of Health (MoH) in Mexico implemented a multidisciplinary health-care model (MHC) for patients with type-2 diabetes (T2D), which has proven more effective in controlling this condition than the conventional health-care model (CHC). RESEARCH DESIGN AND METHODS: We compared the cost-effectiveness of the MHC vs. the CHC for patients with T2D using a quasi-experimental, retrospective design. Epidemiologic and cost data were obtained from a randomly selected sample of health-care units, using medical records as well as patient- and facility-level data. We modelled the cost-effectiveness of the MHC at one, 10 and 20 years using a simulation model. RESULTS: The average cumulative costs per patient at 20 years were US$4,225 for the MHC and US$4,399 for the CHC. With a willingness to pay one gross domestic product (GDP) per capita per quality-adjusted life year (QALY) (US$8,910), the incremental net benefits per patient were US$1,450 and US$3,737 at 10 and 20 years, respectively. The MHC was cost-effective from the third year onward; however, increasing coverage to 500 patients per year rendered it cost-effective at year one. CONCLUSIONS: The MHC is cost-effective at 10 and 20 years. Cost-effectiveness can be achieved in the short term by increasing MHC coverage.

Relevance of quantification in brain PET studies with 18F-FDG. / Relevancia de la cuantificación en los estudios PET cerebrales con 18F-FDG.

The inclusion of 18F-FDG PET as a biomarker in the diagnostic criteria of neurodegenerative diseases and its indication in the presurgical assessment for drug-resistant epilepsies allow to improve specificity of these diagnosis. The traditional interpretation of neurological PET studies has been performed qualitatively, although in the last decade, several quantitative evaluation methods have emerged. This technical development has become relevant in clinical practice, improving specificity, reproducibility and reducing the interrater reliability derived from visual analysis. In this article we update/review the main imaging processing techniques currently used. This may allow the Nuclear Medicine physician to know their advantages and disadvantages when including these procedures in daily clinical practice.

Amyloid PET in neurodegenerative diseases with dementia. / PET amiloide en enfermedades neurodegenerativas que cursan con demencia.

Alzheimer's disease (AD) is a neurodegenerative condition characterized by progressive cognitive decline and memory loss, and is the most common form of dementia. Amyloid plaques with neurofibrillary tangles are a neuropathological hallmark of AD that produces synaptic dysfunction and culminates later in neuronal loss. Amyloid PET is a useful, available and non-invasive technique that provides in vivo information about the cortical amyloid burden. In the latest revised criteria for the diagnosis of AD biomarkers were defined and integrated: pathological and diagnostic biomarkers (increased retention on fibrillar amyloid PET or decreased Aß1-42 and increased T-Tau or P-Tau in CSF) and neurodegeneration or topographical biomarkers (temporoparietal hypometabolism on 18F-FDG PET and temporal atrophy on MRI). Recently specific recommendations have been created as a consensus statement on the appropriate use of the imaging biomarkers, including amyloid PET: early-onset cognitive impairment/dementia, atypical forms of AD, mild cognitive impairment with early age of onset, and to differentiate between AD and other neurodegenerative diseases that occur with dementia. Amyloid PET is also contributing to the development of new therapies for AD, as well as in research studies for the study of other neurodegenerative diseases that occur with dementia where the deposition of Aß amyloid is involved in its pathogenesis. In this paper, we review some general concepts and study the use of amyloid PET in depth and its relationship with neurodegenerative diseases and other diagnostic techniques.

Concordance between brain 18F-FDG PET and cerebrospinal fluid biomarkers in diagnosing Alzheimer's disease. / Concordancia entre la PET cerebral con 18F-FDG y los biomarcadores en líquido cefalorraquídeo en el diagnóstico de enfermedad de Alzheimer.

OBJECTIVES: Cortical posterior hypometabolism on PET imaging with 18F-FDG (FDG-PET), and altered levels of Aß1-42 peptide, total Tau (tTau) and phosphorylated Tau (pTau) proteins in cerebrospinal fluid (CSF) are established diagnostic biomarkers in Alzheimer's disease (AD). An evaluation has been made of the concordance and relationship between the results of FDG-PET and CSF biomarkers in symptomatic patients with suspected AD. MATERIAL AND METHODS: A retrospective review was carried out on 120 patients with cognitive impairment referred to our Cognitive Neurology Unit, and who were evaluated by brain FDG-PET and a lumbar puncture for CSF biomarkers. In order to calculate their Kappa coefficient of concordance, the result of the FDG-PET and the set of the three CSF biomarkers in each patient was classified as normal, inconclusive, or AD-compatible. The relationship between the results of both methods was further assessed using logistic regression analysis, including the Aß1-42, tTau and pTau levels as quantitative predictors, and the FDG-PET result as the dependent variable. RESULTS: The weighted Kappa coefficient between FDG-PET and CSF biomarkers was 0.46 (95% CI: 0.35-0.57). Logistic regression analysis showed that the Aß1-42 and tTau values together were capable of discriminating an FDG-PET result metabolically suggestive of AD from one non-suggestive of AD, with a 91% sensitivity and 93% specificity at the cut-off line Aß1-42=44+1.3×tTau. CONCLUSIONS: The level of concordance between FDG-PET and CSF biomarkers was moderate, indicating their complementary value in diagnosing AD. The Aß1-42 and tTau levels in CSF help to predict the patient FDG-PET cortical metabolic status.

Fibroelastic pseudotumor elastofibroma dorsi detected by 18F-FDG PET/CT scan and by postherapy radioiodine SPECT/CT. / Seudotumor fibroelástico elastofibroma dorsi detectado por 18F-FDG PET/TC y por 131I SPECT/TC posterapia.

Radioiodine uptake in the thyroid tissue, metastasis of differentiated thyroid cancer (DTC), and in other tissues, depends on the expression of sodium-iodide symporter (NIS). Vascular permeability, effusions, inflammation, and other mechanisms may also play a role in the accumulation of radioactive iodine. A 63-year-old woman underwent radioiodine therapy, as well as a post-therapy whole-body scan, as she was suspected of having lung metastasis from thyroid carcinoma. The scan not only showed uptake at the lung metastasis but also a faint diffuse bilateral uptake in the posterior thorax. On SPECT/CT this uptake was located in a known Elastofibroma Dorsi (ED) previously diagnosed by contrast CT and viewed in a FDG PET/CT. The radioiodine uptake in ED, especially if typical, is not a diagnostic problem in SPECT/CT study, but can be misleading in a study limited to a few planar images, particularly if the uptake occurs asymmetrically, or ED is located in a unsuspected area.

A new era for Nuclear Medicine neuroimaging in Spain: Where do we start from in Spain? / Nuevos tiempos para la neuroimagen de Medicina Nuclear en España: ¿de dónde partimos?

OBJECTIVE: To determine the status of neuroimaging studies of Nuclear Medicine in Spain during 2013 and first quarter of 2014, in order to define the activities of the neuroimaging group of the Spanish Society of Nuclear Medicine and Molecular Imaging (SEMNIM). MATERIAL AND METHODS: A questionnaire of 14 questions was designed, divided into 3 parts: characteristics of the departments (equipment and professionals involved); type of scans and clinical indications; and evaluation methods. The questionnaire was sent to 166 Nuclear Medicine departments. RESULTS: A total of 54 departments distributed among all regions completed the questionnaire. Most departments performed between 300 and 800 neuroimaging examinations per year, representing more than 25 scans per month. The average pieces of equipment were three; half of the departments had a PET/CT scanner and SPECT/CT equipment. Scans performed more frequently were brain SPECT with 123I-FP-CIT, followed by brain perfusion SPECT and PET with 18F-FDG. The most frequent clinical indications were cognitive impairment followed by movement disorders. For evaluation of the images most sites used only visual assessment, and for the quantitative assessment the most used was quantification by region of interest. CONCLUSIONS: These results reflect the clinical activity of 2013 and first quarter of 2014. The main indications of the studies were cognitive impairment and movement disorders. Variability in the evaluation of the studies is among the challenges that will be faced in the coming years.

Heterogeneity of income and lifestyle determinants of body weight among adult women in Mexico, 2006.

In Mexico, the combined prevalence of overweight and obesity among Mexican women increased from 64% in 2000 to 72% in 2006. In this paper, we report our findings on the relation of women's body mass index (BMI) with income and lifestyles choices using data from a cross-sectional survey conducted in 2006. The two following approaches were executed. First, we estimated a two-stage least-squares regression to control for the potential endogeneity of income stratified by urban or rural residency. The second approach was aimed at exploring whether the determinants of weight varied among different weight levels using latent class models. Our findings from the two-stage least-squares regression show a positive non-significant association between income and BMI in the overall and urban samples but a significant positive relationship among rural women. Our results suggest that one unit increase in income is associated with 4.1% increase in body weight in rural areas. Estimates from the latent class model (LCM) show a positive but marginally significant association between income and BMI in the overall sample only in the class where there is a greater likelihood that women have normal weight or overweight compared to the class with a higher probability of being obese, but we also found a large association in rural areas for both classes. Lifestyle choices were associated with BMI. Results from the two-stage least-squares regressions reveal that more hours sitting per day and a higher percentage of expenditures in sugary beverages were associated with higher BMI levels. In the LCM, for women who eventually belong to the higher body weight class, lifestyles seem to matter more. Findings from this research suggest that policies to tackle the obesity epidemic among adult women should be different for women living in urban and rural areas and women with different weight levels.

Monitoring system for isolated limb perfusion based on a portable gamma camera.

BACKGROUND: The treatment of malignant melanoma or sarcomas on a limb using extremity perfusion with tumour necrosis factor (TNF-alpha) and melphalan can result in a high degree of systemic toxicity if there is any leakage from the isolated blood territory of the limb into the systemic vascular territory. Leakage is currently controlled by using radiotracers and heavy external probes in a procedure that requires continuous manual calculations. The aim of this work was to develop a light, easily transportable system to monitor limb perfusion leakage by controlling systemic blood pool radioactivity with a portable gamma camera adapted for intraoperative use as an external probe, and to initiate its application in the treatment of MM patients. METHODS: A special collimator was built for maximal sensitivity. Software for acquisition and data processing in real time was developed. After testing the adequacy of the system, it was used to monitor limb perfusion leakage in 16 patients with malignant melanoma to be treated with perfusion of TNF-alpha and melphalan. RESULTS: The field of view of the detector system was 13.8 cm, which is appropriate for the monitoring, since the area to be controlled was the precordial zone. The sensitivity of the system was 257 cps/MBq. When the percentage of leakage reaches 10% the associated absolute error is +/-1%. After a mean follow-up period of 12 months, no patients have shown any significant or lasting side-effects. Partial or complete remission of lesions was seen in 9 out of 16 patients (56%) after HILP with TNF-alpha and melphalan. CONCLUSION: The detector system together with specially developed software provides a suitable automatic continuous monitoring system of any leakage that may occur during limb perfusion. This technique has been successfully implemented in patients for whom perfusion with TNF-alpha and melphalan has been indicated.

[In-transit sentinel lymph nodes in malignant melanoma. What is their importance?]. / Ganglios centinela ''en tránsito'' en el melanoma maligno. Cuál es su importancia?

UNLABELLED: The sentinel lymph node (SLN) is the first node in a lymph node basin to receive direct drainage from the primary tumour. However, in some cases, lymphoscintigraphy images demonstrate the presence of lymph nodes located in the area between the primary tumour and the first regional lymph node basin. These nodes are called in-transit nodes and have to be considered SLNs as well. AIM: It was to determine the incidence and location of in-transit SLNs in patients with malignant melanoma and to evaluate whether it is necessary to harvest them. METHOD. Nine hundred patients with malignant melanoma were included. Lymphoscintigraphy was performed on the day before surgery following intradermal injection of 74-111 MBq of 99mTc-Nanocolloid in four doses around the primary lesion or the biopsy scar. RESULTS: The presence of in-transit SLNs was revealed in 80 patients. During surgery, in-transit SLNs were identified and excised in all but 3 patients (96.2 %). Metastatic cell deposits were identified in these in-transit SLNs in 15 patients (19.4 %), with 4 patients with no tumour involvement of the regional lymph node basin. CONCLUSIONS: Lymphoscintigraphy is mandatory in the location of in-transit SLNs. Moreover, although the incidence of these nodes is relatively low in malignant melanoma, the presence of metastatic cells in these in-transit SLNs reaches a significant percentage. Therefore, excision of in-transit SLNs is necessary in all cases.

[Potential use of bone marrow scintigraphy in suspected prosthetic hip infection evaluated with 99mTc-HMPAO-leukocytes]. / Valor de la gammagrafía de médula macrofágica en el diagnóstico de infección de prótesis total de cadera estudiada con leucocitos Tc-HMPAO.

AIM: To evaluate the usefulness of (99m)Tc-Sulphur colloid when combined with leukocyte scintigraphy in suspected prosthetic hip infection, comparing the results with information from (99m)Tc-HMPAO-leukocyte scintigraphy alone. MATERIALS AND METHODS: Seventy patients (42 women, 28 men; mean age 68 +/- 13 years) with painful hip prostheses and suspicion of infection were evaluated prospectively. All patients had bone scintigraphy, (99m)Tc-HMPAO-labelled white blood cell scintigraphy and (99m)Tc-Sulphur colloid bone marrow scintigraphy. ESR and CRP levels were measured in all patients. The final diagnosis was made with microbiological findings or by clinical follow up of at least 12 months. RESULTS: Infections were diagnosed in 12 of the 70 patients (3 coagulase-negative Staphylococcus, 2 Staphylococcus aureus, 2 Staphylococcus epidermidis, 2 enterococcus and 3 polymicrobial agents). ESR and CRP values were higher in patients with infection than in patients without infection (51.8 +/- 29.4 vs. 25.4 +/- 16.4 and 2.8 +/- 2.2 vs. 1.1 +/- 1.3, respectively; p < 0.05). Bone scintigraphy did not show a characteristic pattern to differentiate infection from aseptic loosening. The pool phase of the bone scintigraphy was positive in only 3/12 patients with infection (25 %). Sensitivity and specificity of the leukocyte scintigraphy was 83 % and 57 %, respectively. When the results of the bone marrow scintigraphy were added, these values increased to 92 % and 98 %, respectively. CONCLUSION: Performing bone marrow scintigraphy significantly improves results when compared with leukocyte scintigraphy alone in the diagnosis of infected hip prostheses. Bone scintigraphy did not help to differentiate aseptic loosening from infection in this series.

[Localization of sentinel node in squamous cell carcinoma of the penis. Initial experience]. / Localización del ganglio centinela en el carcinoma escamoso de pene. Experiencia inicial.

OBJECTIVE: To assess the validity of radioguided sentinel node biopsy in squamous cell penile carcinoma. MATERIAL AND METHODS: Fifteen patients were studied. The first 5 patients were included in a group for validation of the technique, in which a standard inguinal lymphadenectomy was performed after the procedures described below. The remaining 10 patients were included in the technique application group. The day before surgery, lymphoscintigraphy was performed on all patients. During the operation, radioguided biopsy to locate the sentinel node was done. Methylene blue dye was injected shortly before surgery in 10 patients. All patients were followed for an average of 32 months. RESULTS: In the validation group, lymphoscintigraphy revealed inguinal drainage in 5/5 patients. Unilateral metastases were detected in 3/5 patients. No metastatic nodes were detected among the nodes removed during inguinal lymphadenectomy. In the application group, lymphoscintigraphy showed inguinal drainage in 9/10 patients. Nineteen nodes were removed, none of which showed tumour involvement. During the follow-up period, no disease progression or recurrence were observed in either patient group. CONCLUSIONS: Radioguided localization and biopsy of the sentinel nodes can avoid unnecessary lymphadenectomies in patients with squamous cell penile carcinoma and high or intermediate risk of lymph node involvement. This technique shows high reliability and negative predictive value in penile carcinoma.

Radioguided occult lesion localisation in breast cancer using an intraoperative portable gamma camera: first results.

PURPOSE: The role of the radioguided occult lesion localisation (ROLL) technique in breast cancer has been increasing in recent years. One of the important drawbacks of such a technique is radiotracer spillage within the mammary gland that makes the precise lesion resection difficult, and this requires the use of a hook-wire collocation to reach the lesion. The possibility of obtaining an intraoperative image of the specimen could help to confirm whether the lesion is correctly removed. Some types of portable gamma cameras have been designed, but up to now, intraoperative use has been confined to surgery of parathyroid adenomas and sentinel lymph node location. The aim of the study was to value the usefulness of an intraoperative gamma camera to assess the resection of non-palpable breast lesions. MATERIALS AND METHODS: The study involved 42 women diagnosed with non-palpable early breast cancer. Lymphoscintigraphy was performed on the day before surgery by injection of (99m)Tc-labelled nanocolloid. During surgery a gamma probe was used to guide the surgeon, and afterwards images of the surgical bed and the tumoral specimen were acquired by means of a portable gamma camera, fitted with a pinhole collimator. A (99m)Tc pointer was used to draw an outline image around the specimen. RESULTS: On lymphoscintigraphy, radiotracer was concentrated in 31 cases. During surgery, all lesions were removed. In the images acquired by the portable gamma camera, the lesion was centred inside the surgical specimen in 23 of 42 cases, non-centred in 15 and in contact in 4 cases. Congruence of 60% was found between the intraoperative images and the histopathological results. The posterior margin was the most frequently involved. The whole acquisition time for the tumoral specimen with its margins was 5 min at most. CONCLUSION: The use of portable gamma cameras in theatre is in an early phase. The short period of time required during the surgical procedure will allow the surgical team to improve this technique until it can replace hand-held probes. The intraoperative acquisition of such images can predict the involvement of surgical margins, avoiding future surgical procedures.

[Usefulness of 111In-oxine labelled platelets in the management of febrile syndrome in dialysis patients with non-functional renal allografts]. / Utilidad de la gammagrafía con plaquetas marcadas con 111In-oxina en el manejo del síndrome febril en pacientes en diálisis portadores de injerto renal no funcionante.

AIM: To evaluate the usefulness of 111In-oxine-labelled platelet scan in the therapeutic management of prolonged febrile syndrome in dialysis patients with a non-functional renal allograft. MATERIAL AND METHODS: One hundred and fifty-eight patients (94 men, 64 women; mean age 44 +/- 9 years) were studied. Duration of fever was 42 days (range 7-112). A total of 68 % of the patients (107/158) were on low doses of corticosteroids (<10 mg/day). Platelet scans were performed 48 hours after reinjection of 111In-ixone-labelled platelets. A platelet uptake index (PUI) was calculated by dividing the cpm/pixel in the allograft by the cpm/pixel in a mirror background. A PUI > or = 1.5 was considered as threshold for immunological fever. The final diagnosis of immunological fever was established when it disappeared after transplantectomy, embolization or high doses of corticosteroid therapy. Fever of non-immunological origin was established when it disappeared after antibiotic therapy. RESULTS: In 102/158 patients the fever was considered of immunological origin. In 56/158 patients the fever was considered of non immunological origin. Sensitivity and the specificity of the platelet scan was 80 % and 100 %, respectively. All those patients considered as having fever of immunological origin who had PUI <1.5 had been using corticosteroids during platelet scan. CONCLUSION: 111In-labelled platelet scintigraphy is a useful technique in the therapeutic management of prolonged febrile syndrome in dialysis patients with non-functional renal allograft. The use of corticosteroids can reduce the sensitivity of 111In- labelled platelet scan.