Supratentorial low-grade gliomas. Neuroradiology.

The radiologic modality that most likely provides the imaging information needed in a patient suspected of having a brain tumors is magnetic resonance imaging. A brain tumors can be reliably ruled out, if the standard magnetic resonance examination is performed properly and experts interpret the results as negative for tumor. In this paper we will illustrate morphological aspects of low-grade supratentorial neoplasms, including tumors of neuroepithelial tissue, such as low-grade diffuse fibrillary astrocytomas, and circumscribed astrocytic lesions (pilocytic astrocytoma, pleomorphic xantoastrocytoma and subependymal giant cell astrocytoma). Then the main practical applications of functional imaging in neurosurgery will be also debated.

High-field proton MRS of human brain.

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.

[Early diastolic sound in a patient with hepatocarcinoma]. / Un tono aggiunto protodiastolico in un paziente affetto da epatocarcinoma.

On physical examination an early diastolic sound is usually associated with mitral stenosis, prosthetic mitral valve replacement and chronic constrictive pericarditis. In case of an atrial myxoma, an early diastolic sound can be usually heard due to movement of the tumor towards the tricuspid valve (tumor plop). The following case report shows an example in which an early diastolic sound was heard in a patient presenting with a hepatocellular carcinoma. This sound was due to the presence of a thrombus that originated from the inferior vena cava and invaded the right atrium up to the tricuspid valve. It was thus similar to an atrial myxoma and produced a tumor plop.

[Echographic features in the diagnosis of renal abscess]. / Aspetti ecografici nella diagnosi di ascesso renale.

The Authors emphasize sonographic aspects of Renal Abscess in early phase and in proclaimed disease. The advent of the sonography and its extensive use marked an inversion of tendency in Perinephric Abscess evolution. So it is possible to point out small Abscesses and in early phase. Leukocytes tags Scintiscan and CT can confirm the diagnostic tentative.

3.0-T morphological and angiographic brain imaging: a 5-years experience.

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.

[Magnetic resonance angiography in stenosing-occlusive diseases of the carotid arteries: 3D with time of flight versus 3D with phase contrast]. / Angiografia con Risonanza Magnetica nelle malattie steno-occlusive delle arterie carotidi: 3D con tempo di volo versus 3D con contrasto di fase.

We assessed the comparative sensitivity, specificity and diagnostic accuracy of 3D time of flight (TOF) versus 3D phase contrast (PC) MRA in the study of stenoses/occlusions of the extracranial carotid artery. Fifty-four patients were submitted to MRA because of their symptoms or of signs of cerebrovascular insufficiency. 3D TOF and 3D PC axial slices were acquired with a high field magnet; digital angiography was the gold standard. The parameters of 3D TOF acquisitions were: TR/TE/FA 50/8/20, 1 NEX, 512 x 256 matrix, 16 x 12 FOV, 1 axial slab of 60 slices, 1 mm slice thickness, superior presaturation band, ramp pulse, TA 10-18 minutes. 3D PC parameters were: TR/TE/ FA 25/9/20, 1 NEX, 256 x 128 matrix, 18 x 13 FOV, 1 axial slab of 60 slices, 1 mm slice thickness, VENC 35 cm/s, TA 10-15 minutes. 3D TOF MRA was in agreement with digital angiography in 95.6% of cases (22/23), overestimating a grade 3 stenosis as grade 4 (one case, 4.3%) and underestimating no stenoses. 3D PC MRA was in agreement with digital angiography in 78.2% of cases (18/23), overestimating three stenoses (13%); one grade 1 as grade 2 and two grade 4 as grade 5; two stenoses were underestimated (8.6%); one grade 4 as grade 3 and one grade 4 as grade 2. Sensitivity, specificity and diagnostic accuracy were 91.4%, 98.9% and 95.7% for 3D TOF, versus 83.2%, 97.2% and 92.3% for 3D PC, respectively. The two MRA techniques had different semiology. In spite of outstanding background noise suppression, 3D PC poorly depicted the turbulent flow at the carotid bifurcation in carotid stenoses. Therefore, 3D TOF appears a better technique to study stenoses/occlusions of the extracranial carotid arteries.