Topography of primitive reflexes in dementia: an F-18 fluorodeoxyglucose positron emission tomography study.

BACKGROUND AND PURPOSE: Although primitive reflexes (PRs) are inhibited during the first years of childhood, they may reappear with brain injury. PRs have been linked to frontal lobe dysfunction, but their precise topography has not yet been defined. The purpose of this study was to map which regions of the brain display a reduced glucose metabolism in patients with cognitive impairment and PRs. METHODS: A prospective study was conducted to evaluate PRs in a group of patients assessed due to suspected cognitive decline. Neurological and neuropsychological examinations and (18) F-fluorodeoxyglucose positron emission tomography fused with computerized tomography were performed. Voxel-based brain mapping analysis by means of statistical parametric mapping was used to compare patients with and without PRs. RESULTS: The study included 99 patients (33 diagnosed with Alzheimer's disease, 33 on the frontotemporal dementia spectrum and 33 with other diagnoses). Mean age was 71 ± 9.7 years; time since symptom onset was 3.6 ± 2.9 years. At least one PR was observed in 43 cases (43.4% of the whole sample; 48.5% in the Alzheimer disease group, 63.6% in frontotemporal dementia and 18.2% in the group with other diagnoses). The group of patients with PRs exhibited a decreased cerebral metabolism in the bilateral superior frontal gyri (Brodmann area 6), bilateral putamina and thalami. CONCLUSIONS: The presence of PRs was associated with hypometabolism at the superior frontal gyrus and putamen. This suggests that dysfunction in the corticostriatal motor circuit (supplementary motor area-putamen-thalamus) may constitute the anatomical basis of the recurrence of PRs.

Modification of loco-regional microenvironment in brain tumors by spinal cord stimulation. Implications for radio-chemotherapy.

The effectiveness of radiotherapy and chemotherapy in high grade gliomas (HGG) depends on tumor micro-environment. We summarize our experience of the influence of spinal cord stimulation (SCS) on this micro-environment. Patients with HGG (n = 26) were assessed pre- and post-SCS, using: (1) Doppler in middle cerebral arteries (MCA) and (2) in common carotid arteries (CCA); (3) tumor blood-flow using single photon emission computed tomography (SPECT); (4) tumor-pO(2) (mmHg) using polarographic probes (eight tumor areas from five patients); and (5) tumor glucose metabolism using (18)F-fluoro-2-deoxyglucose ((18)FDG) positron emission tomography ((18)FDG-PET). Pre-SCS: tumor blood-flow was lower (P < 0.001) than peri-tumor areas and healthy contra-lateral areas. Tumor-pO(2) was lower (P < 0.042) than healthy tissue. Tumor glucose metabolism was higher than peri-tumor areas (P = 0.017) and healthy contra-lateral areas (P = 0.048). Post-SCS: there were increases in: MCA blood-flow (P ≤ 0.002), CCA blood-flow (P ≤ 0.013), tumor blood-flow (P = 0.033), tumor glucose metabolism (P = 0.027) and tumor-pO(2) (P = 0.022). The percentage of hypoxic values decreased (P = 0.007). SCS can modify tumor micro-environment. The potential usefulness of SCS in improving the effectiveness of radio-chemotherapy in HGG needs to be evaluated.

¿Es necesaria la técnica combinada para la detección del ganglio centinela en el cáncer de mama? / No disponible

Objetivos: Determinar si la punción con colorante mejora los resultados de la biopsia del ganglio centinela. Material y métodos: Ciento cincuenta casos de carcinoma invasor de la mama fueron sometidos a biopsia del ganglio centinela mediante técnica combinada, para determinar si la punción con colorante es rentable. Se realizó inyección subareolar indérmica de una dosis de 0,4 mCi de radioisótopico el día previo a la cirugía. Se practicó gammagrafía en todos los casos. La inyección intraparenquimatosa de 4 cc. de colorante se realizó 20 minutos antes de la cirugía, y se siguió de masaje mamario. Resultados: La tasa de migración fue 92,3% para el radioisótopo y 75% para el colorante (p = 0,01). La media de ganglios resecados fue mayor para la técnica con colorante: 2,6 vs. 1,2 (p = 0,02). No se observaron diferencias en la tasa de falsos negativos (0,2 vs. 0,4) ni en el valor predictivo negativo. La precisión diagnóstica fue mayor para el radioisótopo (90,3% vs. 75% (p = 0,001). El mismo resultado se obtuvo para el porcentaje de éxito técnico (92,3 vs. 75% (0,001)). Conclusiones: La punción con colorante no añade información a la realizada con radioisótopo. A pesar de que la técnica se debe adaptar a las necesidades del centro y a las habilidades del cirujano, una vez superada la curva de validación la técnica radioisotópica por sí misma aporta suficiente información, con menor morbilidad y coste(AU)

Objetives: To determine whether blue dye enhances sentinel node biopsy detection. Material and methods: One hundred fifty hundred consecutive cases of breast cancer were submitted to sentinel node biopsy by combined technique in order to analyze if vital blue was cost-efective. Radioisotope dose was 0,4 mCi of Tc, subareolar intradermic inyection, the day before surgery. Gammagraphy was performed in every case. Colorant was methylene blue, 4 cc administered by intraparenchimatous inyection in upper-outer quadrant 20 minutes previous to surgery, followed by breast massagge. Results: Migration rate was 92.3% for radioisotope and 75% for colorant (p = 0.01). Mean number of nodes excised was higher for colorant: 2,6 vs. 1,2 (p = 0.02). False negative rate showed no difference (0.2 vs. 0.4) nor did negative predictive value. Accuracy to staging (True neg+ true pos./total) was higher for technecium (90.3% vs. 75% (p = 0.001) and so happenned with percentage of technical success (total- no migration): 92.3% vs. 75% (0.001). Conclusions: Colorant did no add any information concerning axillary status. More nodes had to be excised, and bigger incisions were made to achieve direct visualization. Accuracy to stage the lesion and percentage of technical success were higher with radioisotope after the learning curve is achieved and blue injection can be spared(AU)

[Positron emission tomography using 18-FDG-PET in radiologically indeterminate pulmonary lesions]. / Tomografía por emisión de positrones mediante PET-18FDG en lesiones pulmonares radiológicamente indeterminadas.

OBJECTIVE: Fluorine-18 deoxyglucose Positron Emission Tomography (FDG-PET) is a non-invasive technique that offers the possibility to define if the radiologically indetermined pulmonary lesions are benign or malignant with high positive and negative predictive values. Considering the indexed literature we can observe that there are few original studies performed with the diagnostic possibilities of our means. For this reason, our main objective is to evaluate the diagnostic accuracy of positron emission tomography in sixty-seven radiologically indetermined pulmonary nodular lesions. MATERIAL AND METHOD: Retrospectively, we evaluated the diagnostic ability of FDG-PET globally (by means of visual and semiquantitative analysis) and partially (only considering the Standardized Uptake Value (SUV)), in sixty-seven patients confirmed by pathology or clinical and radiological monitoring, in a time interval superior to one year. RESULTS: Globally, FDG-PET had a sensitivity (S) of 92%, specificity (SP) of 86.6%, positive predictive value (PPV) of 89.4%, negative predictive value (NPV) of 89.6% and diagnostic accuracy (DA) of 89%. The best results were obtained for an SUV equal or superior to 2.5. With this value, the clinical efficacy parameters were: S 0.92, SP 0.90, PPV 0.92, NPV 0.90 and DA 0.91. CONCLUSIONS: We can characterize most of the radiologically indetermined pulmonary lesions by FDG-PET. The additional use of SUV facilitates an increase in the positive predictive value and specificity of FDG-PET.

Biphasic response to dobutamine predicts improvement of left ventricular dysfunction after revascularization: correlation with positron emission and rest-redistribution 201Tl tomographies.

BACKGROUND: Dobutamine echocardiography (DSE), positron emission tomography (PET) and 201Tl-single photon emission computed tomography (SPECT) have been used to identify myocardial viability. There are few reports, however, that compare high doses DSE with myocardial metabolic and perfusion imaging techniques in the same patient population. The aim of this study was to determine the correlation between high doses DSE, metabolic PET and 201Tl-SPECT imaging to predict the recovery of function after revascularization in patients with severe left ventricular (LV) dysfunction. METHODS: Twenty-five patients underwent DSE (up to 40 microg/kg/min), rest and 4-hour redistribution 201Tl SPECT, rest 13N-ammonia and 18fluoro-deoxy-glucose PET imaging and coronary angiography 7-10 days before surgical revascularization. A follow-up 2D-echocardiography was performed 6 weeks after surgery. RESULTS: Of the 109 successfully revascularized segments with severe dysfunction, 62 (57%) improved. LV ejection fraction increased from 30 +/- 10% to 42 +/- 13 at follow-up (p < 0.05). 201Tl SPECT, PET and the presence of contractile reserve determined by DSE had a similar sensitivity (77-87%) to predict recovery of function, but specificity was higher for the PET mismatch pattern and biphasic DSE (85-89%) than for any of the 201Tl viability patterns (19-64%). The highest positive predictive values were obtained by biphasic DSE and PET mismatch pattern (78-79%) compared to all other criteria (54-67%). In a multivariate model, which included evidence of viability by all imaging modalities, biphasic response was the best predictor of regional recovery of function (Odds ratio, OR: 9.9, 95% confidence intervals, 95% CI: 3.5-27.8). CONCLUSIONS: Although DSE and PET had overall comparable results, the presence of contractile reserve by the biphasic response to dobutamine was a best predictor for the improvement of LV contractile function in this group of patients.

Patient surface radiation doses at two PET imaging facilities.

To develop a practical means of auditing the procedures and to optimize the administered radionuclide activity, patient surface radiation doses following the administration of 18FDG for PET imaging have been measured at breast and gonad locations at two PET facilities. Patient dosimetry was performed using LiF TLD-100 chips placed near the breasts and gonads for 2 h following tracer injection. Standard uptake values from the image-reconstruction algorithms of one PET camera were investigated in regions of interest in tomograms of the myocardium and liver with the aim of validating dosimetry at breasts. Mean doses measured on the patient's skin ranged between 3.3 and 6.1 microGy MBq(-1) at the gonads and between 3.9 and 6.4 microGy MBq(-1) at the breasts, noticeably lower than the calculations reported in the literature. These values show good concordance with the injected activities, although they are not proportional. The proportion of injected activity actually contributing to image production seems to decrease gradually as the injected activity increases. Conversely, for a given injected activity, breast and gonadal doses were found to be lower than the values expected from the numerical calculations reported in the literature, showing increasing discrepancies when the injected activity increased. Doses measured at the right breast were consistently higher than for the left, which is indicative of greater radiotracer absorption by the liver compared to the average absorption in the body.

Early diagnosis of recurrent breast cancer with FDG-PET in patients with progressive elevation of serum tumor markers.

BACKGROUND: The aim of this work is to assess the diagnostic value of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG), in the early detection of tumour recurrence in already treated breast cancer patients in apparent complete remission and with a progressive elevation of tumour markers CEA and/or CA 15.3 without any other clinical or instrumental signs of relapses. METHODS: The author studied 45 women (mean age 58+/-12, range 35-80 years) with histological diagnosis of breast cancer who underwent a tumour marker-guided whole body FDG-PET. All patients were in remission, without any other clinical or instrumental signs of relapses, except for the progressive elevation of CA 15.3 and/or CEA, tested during the follow-up. FDG-PET results were controlled by pathology when histological sampling was possible, by other conventional imaging modalities (US, X-rays, CT, MRI) and/or by clinical follow-up up to 12 months at least. RESULTS: FDG-PET findings were evaluated in 38 patients: 27 resulted positive. Among these 27 PET positive patients 24 were true positive and 3 false positive. Tumour marker guided FDG-PET was also able to discover 3 unknown neoplasms not visualized by other modalities. PET revealed 54 sites of intense focal FDG uptake. The anatomical distribution of these sites was 19 skeleton, 18 lymph node basins, 5 liver, 5 pelvic region, 1 lung, 1 pericardium, 1 pleura, 1 contralateral breast, 2 peritoneum and 1 thyroid bed. Forty-eight of these 54 sites of FDG accumulation were confirmed to be metastases. FDG-PET resulted negative in 11 patients and only in 2 of them the other diagnostic modalities were able to discover metastatic lesions; we had 9 true negative and 2 false positive RESULTS. On the basis of our investigation the performances of tumour marker guided FDG-PET per patient are as follows: sensitivity 92% (24/26), specificity 75% (9/12), positive predictive value 89% (24/27), negative predictive value 82% (9/11), accuracy 87% (33/38). CONCLUSIONS: This study demonstrated the clinical utility of tumour marker-guided PET in the follow-up of breast cancer patients. This diagnostic approach allowed to modify the clinical management in those patients in whom a tumor relapse or unexpected primary neoplasm was discovered.

[Tomographic studies of myocardial perfusion normality with 99m Tc-Tetrofosmin. Spanish multicenter study]. / Estudios tomográficos de normalidad de perfusión miocárdica con 99mTc-Tetrofosmina. Estudio multicéntrico español (I). Aspectos técnicos: diseño del estudio y control de calidad.

As a first phase in a nationwide multicenter study to obtain myocardial perfusion normality patterns, this work presents the study design and quality control methodology used to guarantee that the gammacameras fulfilled some minimum quality requirements. The following aspects were considered in the study design in order to guarantee the homogeneity and interchangeability of the results: creation and structure of the work group, data interchange system, data selection and acquisition, centralized archiving and processing, assessment system, study acceptance criteria and distribution of the results. To carry out the instrumental quality control, three phantom studies were established, one to control the rotation center, another to verify tomographic uniformity and a third to simulate the shape and orientation of the left ventricle. The three phantoms circulated through all of the 18 participating centers in this project, which corresponded to 19 gammacameras. Very strict guidelines had to be followed in the acquisition and processing of these phantom studies. If any camera and/or center did not fulfill the criteria established, it was advised of the problem detected in order to correct it. Once the defect was repaired, all the phantoms were sent again for verification. Uniformity of the rotation center was quantified by means of the eccentricity of a 360 degrees orbit, admitting up to a maximum of 10%. Tomographic uniformity was visually assessed, taking in account the number of slices with rings and their contrast and finally no artifacts could be present in the reconstructed study of the ventricle. The center of rotation was within limits in all the cameras except one case while the tomographic uniformity was incorrect in 6 cases. All the departments, except one, corrected the defects detected, and passed the acceptance test. The results made it possible to guarantee adequate homogeneity and instrumental quality in this multicenter study.

[Thallium-201 scintigraphy and dobutamine echocardiography in the assessment of myocardial viability]. / Gammagrafía con talio-201 y ecocardiografía con dobutamina en la valoración de viabilidad miocárdica.

BACKGROUND: The possibility of differentiating viable from non-viable tissue among patients with severe coronary artery disease and severe left ventricular impairment entails relevant clinical and therapeutic implications since it may influence the indication of patient revascularization. To evaluate the presence of myocardial viability two techniques are available in the clinical setting: echocardiography with intravenous infusion of dobutamine and scintigraphy with myocardial perfusion with thalliem-201 by means of single-photon emission tomography. OBJECTIVE: To compare prospectively the value of these techniques for detecting viable myocardium. MATERIAL AND METHODS: Thirty-five patients with severe coronary disease and severe left ventricular dysfunction were included in the study. All patients underwent an echocardiogram using incremental doses of dobutamine, from 5 up to 40 micrograms/kg/min in three-minute periods. For thallium-201 scintigraphy the rest redistribution protocol with delayed images at 4 hours was used. The criteria for detecting viability were: a) for thallium-201, the presence of redistribution in delayed images and normal uptake at rest, and b) for dobutamine echocardiography, a sustained improvement in regional motion, biphasic response, and worsening. RESULTS: By considering the segmental improvement post-revascularization as "gold standard" of viability, the statistically significant variables in a logistic regression model and, therefore, predictors of segmental functional recovery were the biphasic response and the sustained response for dobutamine echocardiography and normal uptake at rest and redistribution in the delayed images for thallium-201. Taken together, the result was significant for the biphasic response of dobutamine echocardiography. CONCLUSIONS: The biphasic response with dobutamine echocardiography is the echocardiographic pattern that best predicts the functional recovery of the ischemic myocardium. A normal uptake and redistribution at four hours is the only scintigraphic pattern that can predict functional improvement. Of both patterns, the biphasic response is the best predictor of the functional recovery of the dysfunctional myocardium.

Gammagrafía con talio-201 y ecocardiografía con dobutamina en la valoración de viabilidad miocárdica / Thallium-201 scintigraphy and dobutamine echocardiography in the assessment of myocardial viability

Introducción y objetivo. La posibilidad de diferenciar el tejido viable del no viable en pacientes con enfermedad coronaria severa y disfunción ventricular izquierda tiene implicaciones clínicas y terapéuticas importantes, pues puede influir en la indicación de revascularización del paciente. Para poder evaluar la presencia de viabilidad miocárdica disponemos en la práctica clínica de dos técnicas: la ecocardiografía con infusión intravenosa de dobutamina y la gammagrafía de perfusión miocárdica con talio-201 mediante tomografía por emisión de fotón único. El objetivo de este estudio fue comparar de forma prospectiva el valor de estas dos técnicas en la detección de miocardio viable. Material y métodos. Se incluyeron en el estudio 35 pacientes con enfermedad coronaria y disfunción ventricular severa. A todos ellos se les realizó una ecocardiografía utilizando dosis progresivas de dobutamina desde 5 hasta 40 µg/kg/min en estadios de tres minutos. Para el talio-201 se escogió el protocolo de reposo-redistribución con imágenes tardías a las cuatro horas. Los criterios para la detección de viabilidad fueron: para el talio-201, presencia de redistribución en las imágenes tardías y la captación normal en reposo; para la ecocardiografía con dobutamina, mejoría mantenida del movimiento regional, respuesta bifásica y el empeoramiento. Resultados. Considerando como patrón oro de viabilidad la mejoría segmentaria postrevascularización, las variables que resultaron estadísticamente significativas en un modelo de regresión logística y, por tanto, predictoras de la recuperación funcional segmentaria fueron para la ecocardiografía dobutamina la respuesta bifásica y la respuesta mantenida y para el talio-201 la captación normal en reposo y redistribución en las imágenes tardías. Cuando valoramos estos patrones juntos el resultado fue significativo para la respuesta bifásica de la ecocardiografía con dobutamina. Conclusiones. La respuesta bifásica de la ecocardiografía con dobutamina es el patrón ecocardiográfico que mejor predice la recuperación funcional del miocardio isquémico. La captación normal y redistribución a las cuatro horas es el único patrón gammagráfico con capacidad de predecir mejoría funcional. De los dos patrones, la respuesta bifásica es la que mejor predice la recuperación funcional del miocardio disfuncionante (AU)

No disponible

[Comparison of dobutamine echocardiography and rest-redistribution 201-thallium SPECT in the assessment of myocardial viability taking PET as gold standard]. / Comparación entre la eco-dobutamina y talio-201 SPECT reposo-redistribución en la valoración de la viabilidad miocárdica considerando el PET como patrón oro.

BACKGROUND AND AIM: To compare Tl-201 SPECT and dobutamine stress echocardiography for the detection of myocardial viability in patients with severe left ventricular dysfunction using metabolic imaging by positron emission tomography as the standard reference. MATERIAL AND METHODS: We studied 25 consecutive patients with severe coronary artery disease and left ventricular dysfunction that underwent two different diagnostic modalities for evaluating myocardial viability: stress echocardiography with incremental doses of dobutamine from 5 up to 40 g/kg/min in 3 min stages, and 201 Tl SPECT using a rest-redistribution protocol with delayed images obtained at 4 hours. Fluorodeoxyglucose uptake by PET was used as the gold standard. Viability criteria were as follows, for 201Tl SPECT imaging: normal uptake at rest and presence of redistribution in the delayed images, for dobutamine stress echocardiography: sustained improvement and biphasic response. RESULTS: Sensitivity of thallium redistribution was 46%, for normal uptake, plus redistribution 82%, 34% for dobutamine biphasic response and 58% for sustained improvement plus biphasic response. Specificity of biphasic response was 82% and that of redistribution 67%. Stepwise logistic regression indicated that biphasic wall motion response during dobutamine stress echocardiography (2.01 CI 95%; 1.10 to 3.99) and the presence of redistribution plus normal uptake at rest with thallium imaging (2.68 CI 95%; 1.42 to 5.13) were the best predictors of viability. These results were the same when both techniques were analyzed together. CONCLUSIONS: Biphasic wall motion response during dobutamine stress echocardiography and the normal uptake plus presence of redistribution with thallium imaging were the best pre

Utility of fluorine-18-fluorodeoxyglucose positron emission tomography in differentiated thyroid carcinoma with negative radioiodine scans and elevated serum thyroglobulin levels.

BACKGROUND: This study aimed to determine the role of fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in the follow-up of patients who underwent total thyroidectomy and iodine-131 ((131)I) ablation therapy for differentiated thyroid cancer and presented increased thyroglobulin levels with negative (131)I and thallium-201 ((201)Tl) scans. METHODS: Two patients with follicular carcinoma and eight with papillary tumors underwent total thyroidectomy and (131)I therapy until the (131)I scan was negative. (131)I and (201)Tl scans were performed with negative results in all cases, while serum thyroglobulin measurements were all positive with negative thyroglobulin autoantibodies. One week after the (131)I scans, all the patients underwent FDG-PET whole-body scans. RESULTS: The FDG-PET scan detected in 4 patients, a single focal increase of FDG uptake in one lymph node metastasis (subsequently confirmed histologically); in 1 patient, multiple pathological focal uptakes in brain, neck, and chest; and in 1 patient, two mild focal uptakes in the mediastinum, close to the tracheal branch. In 2 other patients, pathological FDG uptakes in cervical spine and mediastinum were not confirmed by other imaging techniques, and in the 2 remaining patients the scan results were inconclusive. The sensitivity of FDG-PET whole-body scan for detecting metastatic thyroid cancer was 60%. CONCLUSIONS: This study indicates that the FDG-PET whole-body scan is a useful tool in the follow-up of patients with differentiated thyroid cancer, negative (131)I and (201)Tl scans and elevated serum thyroglobulin levels. The FDG-PET scan detects metastatic disease in 60% of patients with differentiated thyroid cancer, enabling surgical therapy to be performed on accessible lesions.

[PET detection of recurring rectal adenocarcinoma in an unusual location. Case report]. / Detección mediante PET de recidiva de adenocarcinoma rectal de localización inusual. A propósito de un caso.

A rare pattern of colon cancer recurrence is presented. A 63-year-old man underwent surgical resection after diagnosis of colon cancer. The postsurgical-pathologic examination showed a stage II colon cancer (MAC B2). Six courses of adjuvant chemotherapy (Mayo protocol) were started within four weeks of surgery. During follow-up, serial serum carcinoembryonic antigen levels became progressively elevated in an otherwise asymptomatic patient who showed no signs of recurrence in any of the conventional imaging tests performed (chest X-ray, abdominal ultrasound, and abdominal CT-scan). Positive findings suggesting lymph node mediastinal metastases were present in the PET scan. Surgical resection and pathologic examination demonstrated metastases of colon adenocarcinoma.

[Neuroimaging in epilepsy. Advances in SPECT and PET in epilepsy]. / Neuroimagen en epilepsia. Avances en SPECT y PET en epilepsia.

INTRODUCTION: The incorporation of neuroimaging techniques into the protocol for localization of epileptogenous foci has considerably reduced the need for use of intracranial electrodes. DEVELOPMENT: SPECT and PET are most useful in cases of epilepsy with no cerebral morphological anomalies, in which there are therefore no changes which shown on MR. Cerebral SPECT with perfused tracers, such as 99mTc-HMPAO, 123I-MP or 99mTc-ECD, permit the study of patients during interictal and perictal phases. In the latter case, although the procedure is complex, one may observe an increase in cerebral blood flow in the epileptogenous focus in 90% of the patients. PET with FDG allows interictal study of patients, and shows reduced metabolism in the epileptogenic region. By comparison with video-EEG there are S = 84% and SP = 86% in temporal lobe epilepsy. The diagnostic efficiency of these two techniques is rather less in the localization of extratemporal foci and in multifocal epilepsies, although it is always better than with other diagnostic techniques. They have also been shown to be useful in the prognosis of functional recovery after surgery. CONCLUSION: The possibility of studying neuroreceptors may be of great use in the investigation of the etiopathogenesis of epilepsy, and thus lead to improvement in the clinical and therapeutic management of patients. With SPECT, 123I-Iomacenil and 123I-lododexetimide are used. With PET and 11C-Carfentanyl opiate receptors have been studied. With 11C-Fluomacenil one may study the cerebral distribution of the benzodiazepine receptors.

Preliminary safety evaluation of a cyclotron facility for positron emission tomography imaging.

This work describes the design characteristics of a medical imaging centre which uses positron emission tomography, with a cyclotron for fluorine-18 and nitrogen-13 production, and which has provided experimental information on operational data recorded by area dosimetry since 1995. Doses to radiopharmacy and medical staff have been measured both in normal work and in some handling incidents. Data on radiation levels in the installation have also been obtained and related to design details and shielding. Area dosimetry was carried out using a five-stationary detector network, with a sampling rate of 2 min(-1), and by thermoluminescent dosimetry (TLD). Staff were also monitored by TLD, using extra chips for finger dosimetry and to duplicate individual whole-body dosimetry in order to measure doses in certain single operations. For normal work, average whole-body doses to radiopharmacy staff were between 0.03 and 0.28 mSv/month, wrist doses were between 0.42 and 2.67 mSv/month, and finger doses were between 1.4 and 7.7 mSv/day for the left hand and 0.8 and 2.4 mSv/day for the right hand; such variation reflects the differing expertise of staff and the role played by optimisation. Finger doses between 16 and 131 mSv were measured in handling incidents, and finger doses of 20.2 and 20.7 mSv for the left hand and 22.0 and 22.3 mSv for the right hand were measured during handling of a syringe without shielding, containing 3 GBq. For medical staff, contributions to the whole-body dose of 2.0 and 1.9 microSv/procedure were measured for injection and placing the patient on the examination couch, respectively. Dose measurement on the middle finger of the right hand gives an average of 70 microSv during the injection. The provisions regarding the shielding design have proved to be adequate and effective during a 3-year operational period. Operational doses to medical staff are comparatively low, while radiopharmacy staff are the most exposed. The finger doses in these professionals may exceed the annual limit, unless operational restrictions in daily practice are adopted. On-line area dosimetry records based on dose rate probes have proved to be effective both for monitoring radiation levels during the operation and for detecting changes in the behaviour of the facility in the irradiation process.

[PET-FDG in thyroid cancer with high thyroglobulin levels and negative 131-I scan. A case report]. / La PET-FDG en el cáncer de tiroides ante niveles altos de tiroglobulina y rastro 131-I negativo. A Propósito de un caso.

The value of whole body PET-FDG in the evaluation of metastases has been demonstrated in a wide variety of tumors. In this report, we present the case of a patient with antecedent of papillary thyroid carcinoma, who was operated twelve years ago, and submitted to an ablative dose of residual thyroid tissue through 131I, being the levels of thyroglobulin normals. After twelve years of evolution, the patient refers bag pain and respiratory trouble, appearing in the CT image suspicious of metastases in right pulmonary base. The levels of thyroglobulin were shown increased, being the 131I scan negative. A whole body PET-FDG study was performed in order to exclude metastases of his malignant process, showed multiple high FDG uptake focus in brain, cerebellum, neck, chest, lymphatic nodes and bone, suggestive of dedifferentiated disease These findings were confirmed subsequently in the clinic evolution. Therefore, whole-body PET-FDG is a complementary diagnostic technique for study patients with CDT (Thyroid Differentiated Carcinoma) with 131I scan negative and rising thyroglobulin levels.

[The role of PET-FDG in questionable diagnosis of relapse in the presence of radionecrosis of brain tumors]. / Papel de la PET-FDG ante la duda diagnóstica de recidiva frente a radionecrosis en tumores cerebrales.

INTRODUCTION: Although CT and MR are sensitive techniques for the detection of cerebral tumours, both have limitations in distinguishing between tumour relapse (TR) and post-treatment radionecrosis (RN). PATIENTS AND METHODS: In this study we have determined the usefulness of metabolic imaging with PET-FDG in such situations. We assessed 70 patients with CNS tumours (22 low grade astrocytomas, 25 high grade astrocytomas, 3 oligodendrogliomas, 13 metastatic tumours and 7 other tumours. All had been treated with radiotherapy and other treatments such as radiosurgery, chemotherapy or different types of surgery, and presented clinical pictures which made it necessary to decide the differential diagnosis of relapse or radionecrosis. RESULTS: In the PET-FDG study visual and semiquantitative analysis was done by SUV (Standardized Update Value). Confirmation of the findings was obtained in 44 cases (24 TR and 20 RN). MR was doubtful or inconclusive in most cases, whilst with PET correct diagnosis was made in all cases. CONCLUSIONS: Metabolic imaging with PET-FGD is better than anatomostructural imaging techniques for differential diagnosis between tumour relapse and radionecrosis in CNS tumours which have been treated. Prospective studies are necessary for evaluation of SUV as a factor for prognosis of survival.