Cerebral networks of sustained attention and working memory: a functional magnetic resonance imaging study based on the Continuous Performance Test.

INTRODUCTION: One of the most used paradigms in the study of attention is the Continuous Performance Test (CPT). The identical pairs version (CPT-IP) has been widely used to evaluate attention deficits in developmental, neurological and psychiatric disorders. However, the specific locations and the relative distribution of brain activation in networks identified with functional imaging, varies significantly with differences in task design. AIM: To design a task to evaluate sustained attention using functional magnetic resonance imaging (fMRI), and thus to provide data for research concerned with the role of these functions. SUBJECTS AND METHODS: Forty right-handed, healthy students (50% women; age range: 18-25 years) were recruited. A CPT-IP implemented as a block design was used to assess sustained attention during the fMRI session. RESULTS: The behavioural results from the CPT-IP task showed a good performance in all subjects, higher than 80% of hits. fMRI results showed that the used CPT-IP task activates a network of frontal, parietal and occipital areas, and that these are related to executive and attentional functions. CONCLUSIONS: In relation to the use of the CPT to study of attention and working memory, this task provides normative data in healthy adults, and it could be useful to evaluate disorders which have attentional and working memory deficits.

TITLE: Bases cerebrales de la atencion sostenida y la memoria de trabajo: un estudio de resonancia magnetica funcional basado en el Continuous Performance Test.Introduccion. Uno de los paradigmas mas utilizados en el estudio de la atencion es el Continuous Performance Test (CPT). La version de pares identicos (CPT-IP) se ha utilizado ampliamente para evaluar los deficits de atencion en los trastornos del neurodesarrollo, neurologicos y psiquiatricos. Sin embargo, la localizacion de la activacion cerebral de las redes atencionales varia significativamente segun el diseño de resonancia magnetica funcional (RMf) usado. Objetivo. Diseñar una tarea para evaluar la atencion sostenida y la memoria de trabajo mediante RMf para proporcionar datos de investigacion relacionados con la localizacion y el papel de estas funciones. Sujetos y metodos. El estudio conto con la participacion de 40 estudiantes, todos ellos diestros (50%, mujeres; rango: 18-25 años). La tarea de CPT-IP se diseño como una tarea de bloques, en la que se combinaban los periodos CPT-IP con los de reposo. Resultados. La tarea de CPT-IP utilizada activa una red formada por regiones frontales, parietales y occipitales, y estas se relacionan con funciones ejecutivas y atencionales. Conclusiones. La tarea de CPT-IP utilizada en nuestro trabajo proporciona datos normativos en adultos sanos para el estudio del sustrato neural de la atencion sostenida y la memoria de trabajo. Estos datos podrian ser utiles para evaluar trastornos que cursan con deficits en memoria de trabajo y en atencion sostenida.

Cervical spine involvement in rheumatoid arthritis: correlation between neurological manifestations and magnetic resonance imaging findings.

OBJECTIVE: To evaluate the correlation between neurological deficits indicative of compressive myelopathy and MRI findings in a series of patients with RA and symptomatic involvement of the cervical spine. METHODS: Forty-one consecutive patients with RA were studied using cervical spine MRI. Unconditional logistic regression analysis was used to identify MRI parameters of cervical spine involvement associated with the development of neurological dysfunction. RESULTS: The mean age of the 41 patients (33 women and 8 men) was 59 yrs (range 23-82 yrs), while the median disease duration was 18 +/- 9 yrs (range 4-40 yrs). According to Ranawat's classification, 17 (42%) patients were in Class I, 21 (51%) in Class II and 3 (7%) in Class III. Thus, patients with clinical manifestations of compressive myelopathy (Ranawat's Class II + III) represented 58% (24/41) of all cases. Among the different MRI parameters of cervical spine involvement analysed, only the presence of atlantoaxial spinal canal stenosis [odds ratio (OR) 4.55; 95% CI 1.14-18.15], atlantoaxial cervical cord compression (OR 9.6; 95% CI 1.08-85.16) and subaxial myelopathy changes (OR 11.43; 95% CI 1.3-100.81) were associated with a significantly increased risk for neurological dysfunction (Ranawat's Class II or III). CONCLUSION: In RA patients with symptomatic cervical spine involvement, there is a strong correlation between the development of neurological dysfunction and MRI identification of atlantoaxial spinal canal stenosis, especially in those cases with evidence of upper cervical cord or brainstem compression and subaxial myelopathy changes.

Utility of proton MR spectroscopy in the diagnosis of radiologically atypical intracranial meningiomas.

Our aim was to evaluate the usefulness of proton MR spectroscopy ((1)H MRS) in the diagnosis of radiologically atypical brain meningiomas. We studied 37 patients with intracranial meningiomas with MRI and (1)H MRS (TE 136 ms). Their spectra were quantitatively assessed and compared with those of 93 other intracranial brain neoplasms: 15 low-grade and 14 anaplastic astrocytomas, 30 glioblastomas and 34 metastases. The most characteristic features of meningiomas were the presence of alanine, high relative concentrations of choline and glutamine/glutamate and low concentrations of creatine-containing compounds, N-acetyl-containing compounds and lipids. These resonances were assembled in algorithms for two-way differentiation between meningioma and the other tumours. The performance of the algorithms was tested in the 130 patients using the leave-one-out method, with 94% success in differentiating between meningioma and other tumour. Of the 37 meningiomas, five (14%) were thought atypical on MRI, and in only one of these, found to be malignant on histology, was a diagnosis other than meningioma suggested by the algorithm. The other four were correctly classified. We suggest that (1)H MRS provides information on intracranial meningiomas which may be useful in diagnosis of radiologically atypical cases.

[Panoramic radiography using an intraoral tube. Method, anatomy, radiography and dosimetry]. / La radiografia panoramica con sorgente endorale. Tecnica, anatomia radiografica e dosimetria.

BACKGROUND: There are two techniques giving a panoramic view of the dental arch: orthopantomography and intraoral tube panoramic radiography. The last one is not very well known because images, with a characteristic and variable deformity if compared with orthopantomography are not useful for routinary use in dentistry. The poor radiographic and pathologic anatomy knowledge of intraoral tube panoramic radiography, and the slight improvements brought to the method particularly in order to reduce the dose, partly depend on the scant attention given to the method by investigators, and partly on the dyshomogeneous anatomic sites enlargement and overlapping with consequent deformity of all of them. With intraoral tube panoramic radiography, X-ray exposition is emitted using a miniaturized cylindrical source placed inside the oral cavity and the radiographic film is in contact with the skin of the face. Based on the orientation of the collimator and the inclination of the tube major axis in the oral cavity, a central technique (exposition of either superior or inferior dental arch) and a lateral technique (simultaneous exposition of the two hemiarches of the same side) are recognized. The aim of this study is to give a significative contribution to maxillo-facial characteristic appearance and dosimetry knowledge in intraoral tube panoramic radiography. METHODS: It consists of: a) a "laboratory" part concerning the evaluation of the enlargement, deformation and visibility of different structures, obtained by positioning about fifty different markers in different maxillary and mandibular anatomic sites, and b) an in vivo dosimetry part obtained with intraoral and extraoral termoluminiscent dosimeters. An original dispositive allowed the right positioning of the film and its adherence to the screen. Deformity characteristics are analitically described and discussed in relation with the different sites. RESULTS AND CONCLUSIONS: The use of intensifying screens allowed a good reduction of dose, (mean absorbed doses ranging from 25 microGy in the intraoral sites to 1936 microGy in the extraoral sites) without reducing the image quality thanks to the device performed "ad hoc".

[Doppler ultrasonography of the intrarenal arteries before and after radiologic treatment in obstructive uropathy]. / Eco Doppler delle arterie intrarenali prima e dopo trattamento radiologico nell'uropatia ostruttiva.

Resistive index (RI) calculation on Doppler tracing of intrarenal arterial blood flow is a sensitive method for the early diagnosis of obstructive uropathy. However, the RI is not specific and can increase in a number of other conditions, e.g., old age, circulating endogenic factors or drugs, other nephropathies. The authors investigated RI usefulness and accuracy by measuring it both before and after the radiologic treatment of acute urinary obstruction in 21 patients, 9 of whom had chronic renal failure due to other causes, i.e., hypertension, diabetes and chronic pyelonephritis. The clinical conditions of the patients limited the feasibility of RI measurements before and after nephrostomy to 66%. In 22 kidneys in 17 patients examined before nephrostomy, the RI ranged 0.63 to 0.93 (mean: 0.80); when the obstruction was unilateral, the RI was always higher than in the contralateral kidney. In 25 kidneys in 18 patients examined after nephrostomy, the mean RI value was 0.68 (15% lower than before). Taking 0.7 as the cut-off value, RI sensitivity in detecting acute urinary obstruction was high (about 90%), while its specificity was low (about 50%); specificity increased (to about 80%) when other concomitant causes of increased intrarenal arterial resistance, e.g., other vascular or parenchymal nephropathies, were not considered. In some cases, the method was also useful in excluding the presence of recurrent obstruction after ureteral stent removal. In conclusion, Doppler US values of intrarenal arterial perfusion are indicative of acute urinary obstruction when they can be compared with those from the contralateral healthy kidney or when they can be measured, in the same patient, before and after decompressive nephrostomy. In other cases, other nephropathies and some technical limitations must be considered.

Interventional radiology of the adrenal glands.

Interventional radiology of the adrenal glands comprises angiographic and percutaneous procedures. Vascular maneuvers have never received widespread application. Venous retrograde adrenal gland ablation fell into disuse because it induced only temporary reduction of adrenal function, caused intense long lasting pain, and was considered unsafe. Chemoembolization of cortico-adrenal carcinoma has been shown to slow tumor growth and may be employed if the patient is inoperable. Percutaneous FNB, routinely performed in large hospital centers, has a high diagnostic yield and a low complication rate. The procedure is performed in the staging of oncological cases or in patients with incidentally found adrenal lesion with no evidence of adreno-cortical or adrenal medullary hypersecretion. Abscesses and adrenal cysts are rarely encountered in clinical practice. Percutaneous drainage of such lesions is readily accomplished under radiological guidance with little hazard for the patient. Furthermore treatment failure does not compromise surgical treatment. Percutaneous ethanol injection has been recently suggested for treatment of hormone producing adreno-cortical adenomas in patients at high surgical risk. Results are promising but further trials are required to ascertain the efficacy and the safety of the procedure.