[Magnetic resonance angiography of the intracranial circle using magnetization transfer contrast (MTC)]. / Angiografia con Risonanza Magnetica del circolo intracranico con tecnica di trasferimento della magnetizzazione (MTC).

Magnetic Resonance Angiography (MRA) is becoming an accurate technique to study vascular conditions, especially when the intracranial circulation is involved. Nevertheless, the contrast-to-noise (C/N) ratio in MRA images is often inadequate to obtain diagnostic images. C/N ratio can be increased by using magnetization transfer contrast (MTC), the technique which allows to reduce the signal from the stationary tissues surrounding vascular structures. To demonstrate the value of MTC, 10 healthy volunteers and 10 patients with different cerebral vascular conditions were examined. All exams were performed using 3D MOTSA (Multiple Overlapping Thin Slab Acquisition) Time of Flight sequences, with and without MTC. A quantitative analysis was carried out in the images with and without MTC, measuring the signal intensity value in the regions of interest at the vascular and stationary structures. A qualitative analysis was also carried out with a double blind study by two independent radiologists. Our results showed that MTC allows to reduce stationary tissues signal intensity, without affecting flowing blood signal intensity. Therefore, the C/N ratio is increased, thus allowing better depiction of smaller peripheral branches. In conclusion, MTC applied to intracranial MRA allows image quality to be markedly improved, with an overall increase in the diagnostic accuracy of this technique.

[Magnetic resonance in gallbladder carcinoma. Its diagnostic reliability]. / La risonanza magnetica nel carcinoma della colecisti. Affidabilità diagnostica.

The use of magnetic resonance imaging (MRI) to study the liver is currently on the increase. Our study was aimed at evaluating MR diagnostic reliability in the detection and staging of gallbladder carcinomas. Thirty-one patients with gallbladder carcinoma were studied. MRI was performed with a 0.5 T superconductive magnet, using spin-echo (SE) T1- and T2-weighted sequences and gradient-echo (GE) refocusing sequences to evaluate portal system patency. Sixteen patients underwent surgery, while 24 were submitted to angio-CT. MR findings correlated well with angio-CT results. In 4 cases only MRI could not define tumor extent due to the presence of breathing artifacts. In 6 cases the tumor was identified at intracholecystic level, while in 21 cases it involved gallbladder fossa and infiltrated liver parenchyma. In 10 of these patients, the lesion involved also the hepatic hilum, while 7 patients exhibited liver metastases. Twenty patients presented lymphadenopathy at both the hilum and the portocaval space. In 8 patients GE refocusing sequences allowed the evaluation of neoplastic thrombosis of the portal vein. Of 16 patients who underwent surgery, MRI underestimated 2 cases--namely, the presence of micrometastases in one case and tumor spread greater than demonstrated by MRI in the other case. To conclude, in our experience MRI can be considered a valuable diagnostic technique to detect and stage gallbladder carcinomas.

[Angiography with magnetic resonance of the ++carotid arteries. Evaluation of clinical results obtained with low magnetic field equipment]. / Angiografia con risonanza magnetica delle arterie carotidi. Validazione dei risultati clinici con apparecchiature a basso campo magnetico.

Magnetic Resonance Angiography (MRA) is the latest diagnostic technique for the noninvasive evaluation of cardiovascular conditions. This technique has proved to be especially useful in the study of carotid arteries. All the clinical studies reported to date have been obtained at high or medium field strength; our purpose is to assess the clinical value of MRA in the evaluation of carotid arteries at low field strength. All the exams were performed with an 0.2 T permanent magnet, using the 2D time of flight (TOF) technique, the only one which is currently available on our equipment. Forty-two patients with clinical diagnosis of cerebrovascular insufficiency were examined. In all cases MRA findings were confirmed with digital subtraction angiography (DSA), which was considered the gold standard. The double-blind evaluation of the results showed high agreement of the two techniques in 70 of 84 carotid arteries. A mild tendency to overestimation was observed in 4 normal cases considered as mild stenoses on MRA, in 2 cases with mild stenosis considered as discrete stenoses on MRA and in 1 case of severe stenosis considered as an occlusion on MRA. Underestimation was seen in 1 case of mild stenosis considered as normal on MRA, in 2 cases of discrete stenosis which appeared as mild stenoses on MRA and in 2 cases of occlusion considered as severe stenoses. Our study showed high agreement between MRA and DSA results, which means that high quality exams can be obtained even at low field strength. Further progress can be expected when 3D TOF and phase-contrast techniques will be introduced.

[Hypermedia software for teaching anatomy of the upper abdomen with computerized tomography and magnetic resonance]. / Programma ipermediale per l'insegnamento dell'anatomia dell'addome superiore con tomografia computerizzata e con risonanza magnetica.

The authors have developed a hypermedia program for creating a tutorial of CT and MR anatomy of the upper abdomen. The program was created on a Mcintosh computer, with the Supercard software: it is made up of a series of windows, each of them containing images, texts, schematic representations and sound. Moreover, each window contains buttons which are activated with the mouse and allow different kinds of function, all created by the authors to be displayed. In particular, navigation buttons allow the users to move in the program either sequentially or non-linearly, according to their needs. The possibility of obtaining information and schematic representations is given by specific buttons. There are also multiple buttons hidden in the images which, when activated, allow the name of the selected organ to be displayed. In conclusion, this program can be especially helpful since it allows different data sets to be integrated to provide the user with complete information. Moreover, the program allows learning to be controlled, that is the user to be informed on timing and methods for more effective studying.

[Magnetic resonance imaging of the esophagus with lumen opacification using a specific contrast agent]. / Studio dell'esofago con risonanza magnetica con opacizzazione del lume mediante impiego di un mezzo di contrasto specifico.

A new contrast agent has been developed for the opacification of the esophageal lumen in Magnetic Resonance (MR) Imaging. The contrast agent consists of an emulsion of low-density and high-viscosity barium paste employed for the CT study of the esophagus (E.Z.E.M., Westbury, USA) and a small amount of Gadolinium-DTPA (Magnevist, Schering, Germany), diluted in 3 ml of saline solution. In vitro evaluation of the contrast solution showed high-signal intensity on T1-weighted SE sequences. The study was subsequently performed on 5 healthy volunteers and 30 subjects with clinical indication for MR Imaging of the chest. The complete opacification of the esophagus was obtained in 12 of the 16 patients (75%) who presented no pathological involvement of the esophagus. The esophageal lumen was completely opacified in 8 patients with esophageal carcinoma and in 1 case of esophageal leiomyoma. In the cases with esophageal carcinoma, lumen opacification allowed the evaluation of tumor growth (concentric or eccentric), a more detailed definition of tumor extent, with assessment of neoplastic wall thickening, and the evaluation of the possible infiltration of adjacent organs. Lumen opacification was obtained in 8 of 10 patients (80%) affected with other chest conditions secondarily involving the esophagus. In these cases, lumen opacification helped to localize the esophagus and to evaluate its involvement by adjacent tumors.