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The role of statistics in medical research starts at the planning stage of a clinical trial or laboratory experiment to establish the design and size of an experiment that will ensure a good prospect of detecting effects of clinical or scientific interest. Statistics is again used during data analysis (sample data) to make inferences valid in a wider population. In simple situations, computation of simple quantities such as P-values, confidence intervals, standard deviations, standard errors or application of some standard parametric or nonparametric tests may suffice. Moreover, despite the wide use of statistics in medical research, simple notions are sometimes misunderstood or misinterpreted by medical research workers, who have only a limited knowledge of statistics. This article, written for non-statisticians, is to explain what are the most common statistical tests used today in the field of medical research, tracing the evolution of statistical tests over time, in particular the introduction of nonparametric methods and, more recently, the NonParametric Combination (NPC) methodology. At the same time, this work seeks to identify some of the errors associated with their use, that often lead to an incorrect assessment and interpretation of results of medical research.

Several studies already demonstrated the clinical relevance of strain rate imaging. Unfortunately, so far only few echolaboratories are using this technique in their clinical practice. This is mainly due to the lack of information on how to perform a standard strain rate imaging study. Thus, the aim of the present review is to provide the bases and methodology to perform a correct strain rate study.

Aim: To describe two cases of Lhermitte-Duclos disease studied with Diffusion MRI and MRi Spectroscopy., Materials and Methods: Two patients showing a space-occupying lesion in the cerebellar hemisphere were studied by conventional MRI associated with Diffusion MRI and Spectroscopy., Results: Conventional MRI showed the typical morphological pattern of Lhermitte-Duclos disease with a slow-growing cerebellar mass mainly involving the cortex and non-enhancing thickened cerebellar folia. The mass exerted mild compression of the IV ventricle causing hydrocephalus On Diffusion imaging showed the lesion to be hyperintense due to residual T2-activity and hypointense on the ADC map. Spectroscopy was typical with an increased lactate peak and a reduced choline peak, indicating abnormal anaerobic glycolysis and demyelination, respectively., Discussion: Lhermitte-Duclos disease is a neurological condition which presents several signs and symptoms related to the cerebellar mass. Cowden's syndrome, an autosomal dominant neoplastic disorder with malignant features is associated in 40% of cases. MRI associated with functional examinations such as Diffusion Imaging and Spectroscopy is the imaging modality of choice in LDD patients. They allow a definite diagnosis as the neuroradiological findings correlate well with molecular biology theories regarding the malformative nature of dysplastic cerebellar gangliocytoma.

Chronic renal failure and haemodialysis patients are prone to develop encephalopathy. The causes of encephalopathy are often unclear. Clinical signs of encephalopathy in the uraemic patient often overlap with several other affections causing neurological disorders. Whenever basal ganglia are anatomically involved, movement disorders arise, including chorea. Some acute and chronic neurological syndromes associated with chronic uraemia have consistently been reported (uraemic encephalopathy, dialysis disequilibrium syndrome, dialysis dementia, nephroangiosclerosis neuropathy and ageing neuropathy). Other clinical conditions in which neurological involvement exists are not so frequent in both haemodialysis patients and in the general population (Wernicke's encefalopathy, Creutzfeldt-Jacob disease). Because of the non specific symptoms and the very heterogeneous aetiology, a careful physical examination should be performed in haemodialysis patients with clinical signs of encephalopathy and the main metabolic alterations should be sought; moreover, central nervous system imaging examination is often appropriate. In case of basal ganglia anatomical involvement, supported by findings of imaging techniques, it is necessary to evaluate individual causes of encephalopathy by means of more accurate tests including analysis of cerebro-spinal fluid, measurement of plasma levels of vitamin B components and laboratory tests searching for more uncommon diseases such as Huntington's chorea and Wilson's disease.

It is well known that rapid myocardial reperfusion, obtained using thrombolysis and/or PTCA, continues to be the best treatment for evolving myocardial infarction. However, a number of experimental studies have drawn attention to the fact that myocardial recovery following reperfusion may be limited by the onset of numerous deleterious biochemical events which occur during reperfusion. Studies carried out after thrombolysis have shown that the perviousness of the vessel and the existence of flow at the level of the epicardial vessels do not necessarily correspond to the recovery of tissue perfusion since a perfusion defect may persist in the presence of angiographically documented anterograde flow. This discrepancy, which occurs during reperfusion, has been attributed to marked cellular enlargement caused by ischaemia both in irreversibly damaged areas and in those which may potentially recover. In basal conditions, endothelial-neutrophil interaction is inhibited by negatively charged molecules present on endothelial cell membranes and by the production of numerous anti-inflammatory substances. During ischemia, on the other hand, anti-inflammatory and endogenous vasodilating substances are depleted in association with the appearance, on the surface of endothelial cells, of molecules favouring leukocyte adhesion. Of these the glycoprotein which has been characterized in greatest detail is the endothelial leukocyte adhesion molecule (ELAM 1) whose production and appearance on the endothelial surface is linked to cytokine-dependent endothelium activation. Ischemia may also stimulate the activation of neutrophils secreting chemiotactical and vasoconstricting factors, and cytotoxic compounds (reactive oxygen metabolites and proteolyte enzymes).(ABSTRACT TRUNCATED AT 250 WORDS)

The diagnosis of spine metastasis is a problem of great interest which leaves many questions unanswered. In this field MR imaging plays a fundamental role, as the only technique able to directly demonstrate the changes in bone marrow tissue, bound to tumoral activity. The introduction of gradient-echo (GE) sequences has helped reduce examination time. Moreover, with the accurate choice of pulse-sequence parameters (TR, TE, flip angle) additional information is acquired which is not yielded by conventional spin-echo (SE) sequences. Our study was aimed at evaluating MR sensitivity in the different stages of bone metastatic evolution. The comparative adequacy was evaluated of combined bone scintigraphy and conventional radiology versus MR imaging in 62 patients with vertebral metastases. Time interval between bone scan and/or radiological study and MR exam ranged from 10 days to 8 months. SE and GE T1-weighted images, and SE and GE T2-weighted images on the sagittal plane were employed, and axial images; coronal images were rarely acquired. Metastases were demonstrated by MR imaging at 122 vertebral levels, versus 88 true positives of combined scintigraphy and conventional radiology. Scintigraphic false-positives were observed at 15 vertebral levels, versus 9 with radiography. GE sequences were superior to SE ones in detecting vertebral morphologic lesions and bone marrow involvement thanks to their improved resolution and sensitivity. Moreover, GE sequences demonstrated tumoral bone marrow spread and persistent tumoral activity in the follow-up of spine metastases. Our results point to GE sequences as those of choice because of their higher resolution and sensitivity, which also allow response to treatment to be evaluated.

The Authors describe a case of paroxysmal atrial fibrillation, in young patients with apparently healthy hearts due to heat stress and expound the pathogenetic mechanisms. They point out the importance of a complete cardiologic examination: sometimes paroxysmal atrial fibrillation is an initial symptom of silent cardiovascular disease.

A case of paroxysmal atrial fibrillation is described and pathogenetic hypothesise are put forward to account for the episode following cranio-cerebral contusive trauma.