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Ever since the introduction of magnetic resonance (MR), imaging with 1.5 Tesla (T) has been considered the gold standard for the study of all areas of the body. Until not long ago, higher-field MR equipment was exclusively employed for research, not for clinical use. More recently, the introduction of 3.0-T MR machines for new and more sophisticated clinical applications has resulted in important benefits, especially in neuroradiology. Indeed, their high gradient power and field intensity (3.0 T) allow adjunctive and more advanced diagnostic methodologies to be performed with excellent resolution in a fraction of the acquisition time required with earlier machines. The purpose of this paper is to illustrate the distinctive semeiological characteristics of 3.0-T morphological and angiographic brain imaging compared with lower-field systems and highlight the respective advantages and drawbacks based on the experience gained in the first 5 years from the installation of a 3.0-T magnet.

In a multicenter evaluation the precision and stability of single slice peripheral Quantitative Computed Tomography (pQCT) systems were assessed. Compared to central Europe the peripheral QCT device is also widely used in the Italian health care system. Phantoms were measured frequently on each machine in four pQCT scanners over a two-year period using an identical automated software program. Intrasite and intersite phantom mineral densities, expressed in units of mg/cm^3, were analyzed and examined. The short and long term precision were estimated from the consistency of these measurements using the root mean square error and expressed as coefficient of variation in percent (% CV). Short term precision was good (mean intrasite coefficient of variation (CV) 0.21\pm 0.056 standard deviation (SD)). Intersite measurements of a single phantom revealed differences between machines of the same type of not more than 2.9 mg/cm^3. At four sites frequent phantom measurements revealed a mean CV of 0.18% (range 0.12-0.28). No significant changes in the regression slopes (drift of the machine versus time) were observed. We conclude that the in vitro precision and stability of the single slice pQCT systems are sufficiently high and unlikely to negatively affect the in vivo precision.

Gli autori illustrano gli aspetti tecnici e semeiologici della sequenza Fast Spin Echo nello studio dei traumi vertebro-midollari acuti. La rapidità di acquisizione, il mantenimento del contrasto Spin Echo e quindi della semeiotica delle lesioni vertebro- midollari, rendono tale sequenza una valida alternativa alla Spin Echo tradizionale, almeno nello studio su piani sagittali. Su piani assiali invece la Gradient Echo risulta ancora superiore alla Fast Spin Echo in virtù di un migliore contrasto sostanza bianca/sostanza grigia midollare e alla mancanza degli artefatti da pulsazione liquorale.

Gli autori illustrano gli aspetti tecnici, semeiologici ed applicativi delle tecniche di soppressione del grasso, con sequenza Fast Spin Echo (FSE) T2 pesata, in Neuroradiologia. L'uso di queste tecniche risulta obbligatorio con la FSE in quanto tale sequenza è caratterizzata da un alto segnale del grasso non solo in T1p, ma anche in T2p. Ciò comporta un'alterazione dell'imaging FSE, rispetto a quello Spin Echo convenzionale, con possibilità di mascherare tutte quelle patologie anch'esse ad alto segnale in T2p. I distretti che possono risentire di tale inconveniente comprendono quelle strutture con ampia componente di grasso quali quelle della testa (orbite, clivus, osso temporale) e soprattutto del rachide, particolarmente ricco di grasso a livello del midollo vertebrale e dello spazio epidurale. Le tecniche più utilizzate sono la CHESS-FSE (Chemical Shift Selective Saturation -FSE) e la STIR-FSE (Short TI Inversion Recovery-FSE). Con entrambe la soppressione del grasso risulta soddisfacente e rapida; ne consegue un aumento della visibilità diagnostica di lesioni quali quelle flogistiche o tumorali (specie ripetitive) altrimenti mascherate dall'alto segnale del grasso.

Questo lavoro prende in considerazione gli aspetti tecnici, semeiologici ed applicativi della sequenza Fast Spin Echo (FSE) nello studio della patologia del distretto spinale. Tale sequenza può essere considerata una Spin Echo (SE) multieco, rapida, caratterizzata infatti da una drastica riduzione del tempo di acquisizione, rispetto alla SE, con conseguente riduzione degli artefatti da movimento e di disagi per i pazienti (specie se sofferenti e non collaboranti). Il tempo risparmiato può essere utilizzato per eseguire esami ad alta definizione, o altre sequenze e proiezioni lungo piani accessori. L'iconografia FSE è molto simile a quello ottenuta con la SE. In realtà esistono alcune lievi differenze semeiologiche che possono talvolta creare dei problemi di interpretazione e che pertanto bisogna tener presenti, quali la persistenza dell'iperintensità del grasso (anche in sequenza T2-W) e la riduzione degli effetti da suscettibilità magnetica. Importanti applicazioni sono l'«effetto mielografico», la possibilità di studiare ampi tratti di colonna (con FOV ampi e bobina del corpo) e di ottenere, con sequenze altamente pesate in T2 la soppressione del grasso e, con rielaborazione MIP, immagini tridimensionali simil-mielografiche.

Grande importanza riveste nella pratica quotidiana la patologia degenerativa del rachide. Essa può presentarsi in quattro forme principali: come alterazioni degenerative del disco intersomatico [condrosi (vacuum discale, riduzione in altezza del disco, etc.) e osteocondrosi (ernie discali intraspongiose e altre irregolarità delle limitanti discosomatiche, osteosclerosi reattiva subcondrale, etc.)]; come artrosi delle articolazioni sinoviali (atlo-assiale, interapofisaria, costo-vertebrale); come spondilosi (caratterizzata dalla presenza di grossolani spondilofiti con relativo risparmio, almeno all'inizio, dello spazio intersomatico); come diffuse calcificazione ed ossificazione dei tessuti molli paravertebrali di sostegno (iperostosi scheletrica diffusa idiopatica, DISH, o malattia di Forestier). Tra i segni elementari ben evidenziabili radiograficamente (ma riconoscibili anche con TC e RM), utili per una diagnosi differenziale vanno ricordati: gli spondilofiti od osteofiti (osteoproduzioni a decorso inizialmente orizzontale), marginali (piccoli, triangolari, da degenerazione del nucleo polposo, nell'osteocondrosi intervertebrale), submarginali (grossolani, con tendenza a saldarsi a ponte, da lesioni delle fibre di Sharpey dell'anello fibroso con trazione sul punto di inserzione del legamento longitudinale anteriore sul soma, nella spondilosi), riparativi (da osteoproduzione reattiva a lesioni traumatiche, flogistiche, neoplastiche, ad instabilità), iperostosici (nella DISH); i sindesmofiti (osteoproduzioni a decorso verticale), marginali (da calcificazione delle fibre periferiche dell'anulus, nella spondilite anchilosante e nella MDPC), non marginali (parasindesmofiti, paradiscali, nelle spondiloartriti seronegative), la cui patogenesi è però flogistica; le ossificazioni e calcificazioni ligamentose paravertebrali (idiopatiche, da spondiloartriti seronegative, da DISH). Due sono le complicanze più comuni della patologia degenerativa del rachide: la spondilolistesi e la stenosi del canale vertebrale. Esse si giovano sempre di un'integrazione di studio con TC e/o RM.

L'osteoporosi, una delle malattie sociali più rilevanti e costose, si manifesta prevalentemente nella seconda metà della vita ed è caratterizzata dalla presenza di fratture atraumatiche. Pertanto una diagnosi di osteoporosi il più precoce possibile è molto importante in termini di profilassi e di trattamento. Negli anni passati c'è stato un considerevole progresso nello sviluppo e nell'applicazione clinica dei metodi non invasivi per misurare la massa ossea (densitometria ossea). Questo articolo rivisita le metodiche densitometriche tradizionali: densitometria a singolo raggio fotonico (SPA), densitometria a doppio raggio fotonico (DPA), densitometria a raggi x a doppia energia (DXA), tomografia computerizzata quantitativa (QCT) e le più moderne tecniche come gli Ultrasuoni (QUS) e la risonanza magnetica (QMR). Il crescente interesse per la densitometria ossea porterà certamente ulteriori miglioramenti tecnologici e renderà più semplice la comprensione della complessa biomeccanica del tessuto osseo, per predire, in ultima analisi, più accuratamente il rischio di fratture.

The objective of this study was to evaluate the potential role of newly developed, advanced magnetic resonance (MR) imaging techniques (spectroscopy, diffusion and perfusion imaging) in diagnosing brain gliomas, with special reference to histological typing and grading, treatment planning and posttreatment follow-up. Conventional MR imaging enables the detection and localisation of neoplastic lesions, as well as providing, in typical cases, some indication about their nature. However, it has limited sensitivity and specificity in evaluating histological type and grade, delineating margins and differentiating oedema, tumour and treatment side-effects. These limitations can be overcome by supplementing the morphological data obtained with conventional MR imaging with the metabolic, structural and perfusional information provided by new MR techniques that are increasingly becoming an integral part of routine MR studies. Incorporation of such new MR techniques can lead to more comprehensive and precise diagnoses that can better assist surgeons in determining prognosis and planning treatment strategies. In addition, the recent development of new, more effective, treatments for cerebral glioma strongly relies on morphofunctional MR imaging with its ability to provide a biological interpretation of these characteristically heterogeneous tumours.

This study evaluated the sensitivity of a 3.0-Tesla (T) magnetic resonance imaging (MRI) in measuring cerebral phenylalanine using proton magnetic resonance spectroscopy and in assessing MR-documented white-matter changes by means of diffusion studies (diffusion-weighted imaging, apparent diffusion coefficient map; diffusion tensor imaging) in patients with phenylketonuria. Thirty-two patients with the classical clinical and biochemical deficits of phenylketonuria underwent biochemical (blood phenylalanine), genotypic (phenylalanine hydroxylase gene) and radiological investigation by means of MRI, proton magnetic resonance spectroscopy and diffusion magnetic resonance imaging with a 3.0-T scanner. Periventricular and subcortical white-matter changes were detected on all MR scans. In 29/32 patients, proton magnetic resonance spectroscopy easily documented abnormal signal elevation at 7.36 ppm, corresponding to phenylalanine, despite its low concentration. Phenylalanine signal amplitude relative to the creatine/phosphocreatine signal increased linearly with blood phenylalanine values (r 0.7067; p

Objective: To gain insights into the nature and pathogenesis of white matter (WM) abnormalities in PKU. Methods: Thirty-two patients with phenylalanine hydroxylase deficiency (21 with early and 11 with late diagnosis and treatment) and 30 healthy controls underwent an integrated clinical, neuroimaging (3.0 T MRI, diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI)) and neurochemical (1H MRS) investigation. Results: All patients had white matter abnormalities on T2-weighted (T2W) and fluid-attenuated inversion recovery (FLAIR) scans; parietal white was consistently affected, followed by occipital, frontal and temporal white matter. T1-weighted hypointense alterations were also found in 8 of 32 patients. DWI hyperintense areas overlapped with those detected on T2W/FLAIR. The apparent diffusion coefficient (ADC) was reduced and correlated inversely with severity of white matter involvement. Fractional anisotropy index, eigenvalues λmin, λmiddle, λmax obtained from DTI data, and the principal brain metabolites assessed by 1H MRS (except brain phenylalanine (Phe)) were normal. Brain Phe peak was detected in all but two subjects. Brain and blood Phe were strictly associated. Blood Phe at the diagnosis, patient’s age, and concurrent brain Phe independently influence white matter alteration (as expressed by conventional MRI or ADC values). Conclusions: (a) MRI abnormalities in phenylketonuria are the result of a distinctive alteration of white matter suggesting the intracellular accumulation of a hydrophilic metabolite, which leaves unaffected white matter architecture and structure. (b) White matter abnormalities do not seem to reflect the mechanisms involved in the derangement of mental development in PKU. (c) Our data do not support the usefulness of conventional brain MRI examination in the clinical monitoring of phenylketonuria patients.

The aim of this paper is to illustrate the technical, methodological and diagnostic features of functional imaging (comprising spectroscopy, diffusion, perfusion and cortical activation techniques) and its principal neuroradiological applications on the basis of the experience gained by the authors in the 5 years since the installation of a high-field magnetic resonance (MR) magnet. These MR techniques are particularly effective at 3.0 Tesla (T) owing to their high signal, resolution and sensitivity, reduced scanning times and overall improved diagnostic ability. In particular, the high-field strength enhances spectroscopic analysis due to a greater signal-to-noise ratio (SNR) and improved spectral, space and time resolution, resulting in the ability to obtain high-resolution spectroscopic studies not only of the more common metabolites, but also--and especially--of those which, due to their smaller concentrations, are difficult to detect using 1.5-T systems. All of these advantages can be obtained with reduced acquisition times. In diffusion studies, the high-field strength results in greater SNR, because 3.0-T magnets enable increased spatial resolution, which enhances accuracy. They also allow exploration in greater detail of more complex phenomena (such as diffusion tensor and tractography), which are not clearly depicted on 1.5-T systems. The most common perfusion study (with intravenous injection of a contrast agent) benefits from the greater SNR and higher magnetic susceptibility by achieving dramatically improved signal changes, and thus greater reliability, using smaller doses of contrast agent. Functional MR imaging (fMRI) is without doubt the modality in which high-field strength has had the greatest impact. Images acquired with the blood-oxygen-level-dependent (BOLD) technique benefit from the greater SNR afforded by 3.0-T magnets and from their stronger magnetic susceptibility effects, providing higher signal and spatial resolution. This enhances reliability of the localisation of brain functions, making it possible to map additional areas, even in the millimetre and submillimetre scale. The data presented and results obtained to date show that 3.0-T morphofunctional imaging can become the standard for high-resolution investigation of brain disease.

This study was performed to clarify the role of perfusion-weighted imaging (PWI) at 3 Tesla in the characterisation of haemodynamic heterogeneity within gliomas and surrounding tissues and in the differentiation of high-grade from low-grade gliomas.We examined 36 patients with histologically verified gliomas (25 with high-grade and 11 with low-grade gliomas). PWI was performed by first-pass gadopentetate dimeglumine T2*-weighted echo-planar images, and cerebral blood volume (CBV) maps were computed with a nondiffusible tracer model. Relative CBV (rCBV) was calculated by dividing CBV in pathological areas by that in contralateral white matter.In high-grade gliomas, rCBV were markedly increased in mass [mean+/-standard deviation (SD), 4.3+/-1.2] and margins (4.0+/-1.1) and reduced in necrotic areas (0.3+/-0.3). Oedematous-appearing areas were divided in two groups according to signal intensity on T2-weighted images: tumour with lower (nearly isointense to grey matter) and oedema with higher (scarcely isointense to cerebrospinal fluid) signal intensity. Tumour showed significantly higher rCBV than did oedema (1.8+/-0.5 vs. 0.5+/-0.2; p0.001) areas. In low-grade gliomas, mass (2.0+/-1.5) and margin (2.2+/-1.2) rCBV were significantly lower than in high-grade gliomas (p0.001).Three-Tesla PWI helps to distinguish necrosis from tumour mass, infiltrating tumour from oedema and high-grade from low-grade gliomas. It enhances the magnetic resonance (MR) assessment of cerebral gliomas and provides useful information for planning surgical and radiation treatment.

3.0 T magnetic resonance (MR) scanner, compared to low-field systems, offer several advantages as higher signal/noise ratio (SNR), greater spatial and temporal resolution. Some disadvantages are: the increase of specific absorption rates (SAR) and of acoustic noise, the dielectric resonance, although in the more recent equipment, these problems have largely been resolved by improvements in hardware and software. High filed MR find their best applications in the evaluation of the central nervous system especially with functional studies thanks to raise of magnetic susceptibility and chemical shift effects.

Ischaemic stroke accounts for 70 % of all acute cerebral vasculopathies and is among the leading causes of death and disability in the Western world. It is most often due to brain vessel atherosclerosis and less commonly to infectious arteritis, emboli from the carotid artery or cardiac pump deficits, resulting in systemic hypoperfusion. A significantly reduced blood flow in the vascular territory supplying the affected vessels induces a metabolic tissue imbalance (hypoxia and hypoglycaemia) that gives rise to variably reversible anatomical injury. Four grades of clinical severity can be distinguished on the basis of the duration of symptoms, which are mainly characterized by a focal neurological deficit: 1. TIA (transient ischaemic attack): a sudden-onset, focal, non-convulsive condition that usually resolves within a few minutes and always within 24 h. 2. RIND (reversible ischaemic neurological deficit): symptoms last no more than 48 h and normal conditions are restored within 3 weeks. 3. Progressive stroke: progressive onset of clinical symptoms worsening over the first 24–48 h and leaving a persistent functional deficit. 4. Completed stroke: a stable clinical condition since onset that may improve in time.

Perfusion MRI is a valuable and flexible clinical tool enabling the assessment of regional cerebral haemodynamics using a variety of techniques and playing a relevant role in treatment strategies (e.g. in deciding which patient should undergo thrombolysis).

Combining metabolic, diffusion and haemodynamic information from 1H-MRSI, DWI and PWI with morphological information from conventional MRI undoubtedly improves the assessment of intracranial tumours, increasing the capability to discriminate between different tissues. Furthermore, using high-field MR can allow shorter imaging times for a given resolution, a higher resolution for a given imaging time, or combination of both, due to the higher SNR. Ashort acquisition time is preferable for the fast imaging of ill and sometimes poorly cooperative subjects, especially if long MR protocols are used. High spatial resolution allows high quality imaging and therefore additional diagnostic information. We suggest that the multiparametric MR approach, including 1H-MRSI, DWI and PWI in addition to conventional MRI, at 3 T may provide a non-invasive fast and accurate tool for the formulation of diagnosis and prognosis, the planning of treatment and the monitoring of therapeutic response in patients with brain tumours.

A preliminary study comparing three dimensional time of flight (TOF 3D) Magnetic Resonance angiography (MRA) and spiral CT angiography (SCTA) in the detection and evaluation of internal carotid stenosis. Digital subtraction angiography (DSA) was the gold standard. Twenty patients with clinical signs of cerebrovascular insufficiency underwent MRA, SCTA and DSA within a three day period. Both internal carotid arteries were evaluated for absence or degree of stenosis. Sensitivity, specificity, diagnostic accuracy, concordance, overstimation and understimation were assessed. MRA showed a higher sensitivity, specificity, diagnostic accuracy and concordance compared to SCTA (92% versus 80%, 98,2% versus 96,4%, 96,3% versus 88%, respectively). MRA demonstrated a 5% overstimation rate whereas SCTA demonstrated a 7,5% understimation rate. These differences are not statistically significant. These results suggest that MRA is the more useful, non invasive modality for the detection and evaluation of the internal carotid artery with a greater than 70% stenoses.

Proton magnetic resonance spectroscopy (1H-MRS) of the brain reveals specific biochemical information about cerebral metabolites, which may support clinical diagnoses and enhance the understanding of neurological disorders. The advantages of performing 1H-MRS at higher field strengths include better signal to noise ratio (SNR) and increased spectral, spatial and temporal resolution, allowing the acquisition of high quality, easily quantifiable spectra in acceptable imaging times. In addition to improved measurement precision of N-acetylaspartate, choline, creatine and myo-inositol, high-field systems allow the high-resolution measurement of other metabolites, such as glutamate, glutamine, gamma-aminobutyric acid, scyllo-inositol, aspartate, taurine, N-acetylaspartylglutamate, glucose and branched amino acids, thus extending the range of metabolic information. However, these advantages may be hampered by intrinsic field-dependent technical difficulties, such as decreased T2 signal, chemical shift dispersion errors, J-modulation anomalies, increased magnetic susceptibility, eddy current artifacts, limitations in the design of homogeneous and sensitive radiofrequency (RF) coils, magnetic field instability and safety issues. Several studies demonstrated that these limitations could be overcome, suggesting that the appropriate optimization of high-field 1H-MRS would expand the application in the fields of clinical research and diagnostic routine.