Magnetic resonance imaging in right ventricular dysplasia.

Fifteen patients with right ventricular dysplasia were investigated by T1-weighted spin- and gradient-echo pulse sequences, using a protocol that enabled both a subjective analysis of myocardial signal intensity and a quantitative/qualitative analysis of right and left ventricular function. In 8 patients, 3 investigators independently recognized abnormally hyperintense areas in the anatomic sites usually affected by the disease. In 7 of these patients, these areas showed an overlap with a-dyskinetic areas imaged by both magnetic resonance imaging (MRI) and echocardiography. In 1 patient who underwent a cardiac transplant, MRI of the explanted heart showed an excellent correlation between the distribution of the lesions and the in vivo/in vitro features. The data were compared with those from an equivalent sample of patients affected by dilated cardiomyopathy. In the latter patients, no focal hyperintensities were attributed to any anatomic sites in the right ventricule, and no focal a-dyskinetic foci were observed. Furthermore, the 2 groups of patients were significantly different in regard to dimensional and functional quantitative parameters. The results suggest that MRI is useful in integrating echocardiographic data and can be helpful in diagnosing this disease in late stages.

Fatty infiltration of the liver. Quantification by 1H localized magnetic resonance spectroscopy and comparison with computed tomography.

RATIONALE AND OBJECTIVES: The authors evaluated the degree of fatty infiltration of the liver in subjects with diffuse liver steatosis using image-guided 1H localized MR spectroscopy and correlated the magnetic resonance (MR)-determined fat fraction with the computed tomography (CT) liver/spleen density ratio and histologic evaluation. METHODS: MR measurements were performed at 1.5 T by applying a double-spin-echo localization sequence. Twenty-six patients underwent MR and CT examinations and ultrasound (US)-guided biopsy. Additionally, three healthy volunteers underwent MR examination. Steatosis severity was estimated using 1) the ratio between fat and total MR signal areas; 2) the ratio between liver and spleen CT number; and 3) histologic score. RESULTS: The linear correlation between MR fat/fat-plus-water signal ratio and CT liver/spleen density values ratio is statistically significant. Both techniques correlate well with histologic score. No significant correlation exists between water or fat T2 values and the severity of steatosis. CONCLUSIONS: 1H MR spectroscopy allows a noninvasive estimate of the hepatic fat content.

Low-dose phase contrast x-ray medical imaging.

Phase contrast x-ray imaging is a powerful technique for the detection of low-contrast details in weakly absorbing objects. This method is of possible relevance in the field of diagnostic radiology. In fact, imaging low-contrast details within soft tissue does not give satisfactory results in conventional x-ray absorption radiology, mammography being a typical example. Nevertheless, up to now all applications of the phase contrast technique, carried out on thin samples, have required radiation doses substantially higher than those delivered in conventional radiological examinations. To demonstrate the applicability of the method to mammography we produced phase contrast images of objects a few centimetres thick while delivering radiation doses lower than or comparable to doses needed in standard mammographic examinations (typically approximately 1 mGy mean glandular dose (MGD)). We show images of a custom mammographic phantom and of two specimens of human breast tissue obtained at the SYRMEP bending magnet beamline at Elettra, the Trieste synchrotron radiation facility. The introduction of an intensifier screen enabled us to obtain phase contrast images of these thick samples with radiation doses comparable to those used in mammography. Low absorbing details such as 50 microm thick nylon wires or thin calcium deposits (approximately 50 microm) within breast tissue, invisible with conventional techniques, are detected by means of the proposed method. We also find that the use of a bending magnet radiation source relaxes the previously reported requirements on source size for phase contrast imaging. Finally, the consistency of the results has been checked by theoretical simulations carried out for the purposes of this experiment.

Advances in radiological anatomy of the kidney.

While using cortical nephrotomography to show the architecture and thickness of the cortical septa we have observed, in 76 out of 176 kidneys, the presence of 2 distinct parenchymal elements for which we suggest the term "renunculus". In such cases the upper renunculus is posterior relative to the lower. It lies rather obliquely, running downwards and laterally, while the lower renunculus lies more or less vertically and in front of the upper. The hilum of the upper renunculus as seen on CT is directed anteriorly relative to the corneal plane: the hilum of the lower renunculus is directly more medially. These anatomical observations make it easier to understand the topography and the pathogenesis of some lesions and help the surgeon to plan partial nephrectomy.

The use of abdominal contrast tomography in liver disease.

The value of a high dose infusion technique using urographic contrast medium followed by tomography was studied in 44 patients with liver disease. The method was found to be of value in showing cysts, abscesses and cystic disease of the liver. Large tumours, primary and secondary, can also be demonstrated. Normal bile ducts are not visible, but become apparent when they are dilated.

Grey-scale ultrasonography in the evaluation of carcinoma of the gall bladder.

Ultrasonography was used to evaluate 18 proven cases of carcinoma of the gall-bladder and a prospective diagnosis was correctly achieved in 88.8%. The ultrasonographic findings may be classified into primary and associated. The diagnostic role of ultrasonography is considered and a flow-chart of further investigations is suggested. The diagnostic limits for early detection are underlined.

Radiological anatomy of the kidney revisited.

In recent years some structures or features such as the "inter-renuncular septum", the "echogenic triangle" and the "echogenic line" have been described to support the concept of a kidney resulting from the fusion of two masses or renunculi. To clarify this concept and to understand the meaning of the above echographic features better, the authors have examined prospectively by sonography the kidneys of 50 children, 200 adults with a single collecting system, 25 adults with a duplicated collecting system and 32 cadavers. Furthermore, to help explain the sonographic features, we have examined 32 cadaver kidneys with sonography and 10 cadaver kidneys with magnetic resonance imaging (MRI). The sonographic, MRI and anatomical correlations have shown that the "echogenic triangle" and the "echogenic line" are not renuncular residuals, but simply an extension of the hilar fat visible when the renal sinus is rather deep. The intermediate cortical mass is not a septum dividing the kidney into an upper and lower renunculus, but a column of parenchymal tissue crossing the renal sinus, which, from an anatomical point of view, is an accessory renal lobe. The presence of two renunculi, suggested in a previous study with cortical nephrotomography, has not been confirmed.

Criteria for choice and use of contrast media in intra-arterial D.S.A.

The authors investigated the optimal characteristics of contrast media for use in intra-arterial DSA. 209 injections in 108 patients were evaluated, most of them in the abdominal and peripheral regions. In order to decrease contrast media osmolarity and obtain an adequate mixing with blood, contrast media with low iodine concentration were injected using the same volumes and flow rates of conventional arteriography. Good results were obtained with ionic contrast media, 100 and 150 mgI/ml. depending on the area investigated. The low concentrations allowed the use of ionic agents with an osmolarity very close to that of the non ionic contrast media: the pain has been eliminated and the heat sensation reduced. Furthermore the comparison with the cost of nonionic agents shows a great saving.

Intra-arterial digital angiography of the liver. Preliminary results.

The authors report the preliminary results of the intraarterial digital angiography of the liver. A series of 30 patients were examined comparing conventional and digital technique following the injection of the coeliac, splenic, hepatic and mesenteric arteries. The results obtained with the digital technique have been of good quality and sometimes even better in spite of significant dilution of the contrast medium. It is concluded that intraarterial digital angiography of the liver gives some advantages compared with the conventional technique, that is the use of a much lower concentrated contrast medium, the better visualization of the portal branches and its collaterals and the very low cost of the film material.

Digital subtraction angiography in postoperative evaluation of peripheral vascular disease.

The authors present the results of intravenous Digital Subtraction Angiography (DSA) in 41 patients examined after vascular surgery for peripheral disease. The digital technique has always been able to show the patency of the graft or the existence of complications (obstruction, stenosis, pseudoaneurysm), even in asymptomatic patients. The images were of good or excellent quality in 90% of the cases. The equipment with C-arm proved to be very useful for the oblique projections which were required in about 20% of the examinations.

Grey-scale ultrasonography in the evaluation of primary carcinomas of the bile ducts.

The authors report the echographic findings observed in 24 proven cases of primary carcinoma of the bile ducts. Most tumours, either vegetating or infiltrating with extraductile extension, were recognized on ultrasound. This technique turned out to be accurate in detecting peripheral, hilar and distal ductal carcinomas. Ultrasonography complements PTC and ERCP. Their combined use allows the surgeon a better selection of the cases and of the proper operative procedure.

Impact of technology and technique on the performance of the intravenous D.S.A. of the carotid arteries.

Intravenous Digital Subtraction Angiography (i.v. D.S.A.) was performed at the carotid bifurcation level in 259 patients with clinical or physical findings of a Cerebrovascular Insufficiency (C.V.I.). The angiographic examinations have been performed during two different periods, basically differing for the technology of the digital equipment and for the technique used. The personal experience showed how these two factors are important in determining the quality of the image and therefore the accuracy of the i.v. studies. Images of good quality of the common and internal carotid arteries have been obtained in 73% and 54% of the cases of the first period and in 93% and 82% of the cases of the second period. The role of the i.v. D.S.A. in the management of the C.V.I. depends not only upon the quality of the images, but also upon the surgical policy and from the availability of ultrasounds.

Combined use of ultrasonography and transhepatic percutaneous cholangiography in obstructive jaundice.

The authors have evaluated the results of ultrasonography (US) and transhepatic percutaneous cholangiography (PTC) in 85 patients. The comparative results of US and PTC in the diagnosis of the level (proximal or distal) and the nature (benign or malignant) of the obstruction and in the evaluation of the extension and the site of the lesion are illustrated. PTC is superior in the evaluation of the level and the nature of the obstruction while US gives more information about extension and site of the lesion. It is concluded that US and PTC should be considered as two complementary modalities.

Ultrasonographic aspects of inflammatory and neoplastic diseases of the gallbladder.

The authors present the incidence of the typical ultrasonographic signs of acute cholecystitis (46 cases), chronic cholecystitis (25 cases), cholecystosis (9 cases), empyema (28 cases) and carcinoma of the gallbladder (30 cases). Ultrasonography, together with the clinical picture, enables the identification of the lesion, its extension and evolution in most of the cases. Rarely do differential diagnostic problems exist. The ultrasonographic follow-up examination has been useful in acute inflammatory diseases to evaluate the efficiency of medical therapy and to detect complications which require immediate surgery. The authors emphasize the value of high-resolution real-time technique.

Three-dimensional computed tomography of the acetabulum.

Acetabular fractures represent a complex variety that are classified in different types. Conventional radiology is often inadequate to demonstrate and classify the fractures. Computed tomography (CT) has already been shown to be superior in this field. A further advantage of CT is represented by the recent availability of three-dimensional (3D) images that are realized from axial CT scans by means of a new software. The Authors report the applications of this new software to the study of the normal acetabulum and in patients with fractures. 3D images allows an effective demonstration of the fracture, its irradiation and the dislocation of bone fragments. The information is contained in one or few images rather than many axial images. Therefore the role of 3D images may be considered complementary to axial CT scans.

Routine evaluation of arteriopathies of the lower extremities by digital subtraction angiography.

Intravenous digital subtraction angiography (DSA) was performed in 119 patients with lower extremity ischemia using a 14" amplifier. Four injections of contrast medium were usually necessary for a complete evaluation of this vascular region. Images of good quality were obtained in most cases; movement artifacts and a faint opacification accounted for any poor results, which occurred mainly under the knee. The technique of pixel shifting turned out to be very useful to remove movement artifacts. The "measuring field" allowed us to minimize the problem of the inhomo geneous saturation of the amplifier. In 8% of the cases an intra-arterial DSA has been performed after an unsatisfactory intravenous examination. Conventional angiography appears to be no longer necessary.

The role of ultrasonography in the diagnosis of tumours of the renal pelvis.

The authors have evaluated 22 patients with renal pelvis tumour (RPT) by means of excretory urography and ultrasonography. Six patients also underwent arteriography. The value of the three investigations in the diagnosis of the lesion, the nature, the pyelic origin and the extension are presented. It is concluded that urography remains the method of choice for the evaluation of RPT while ultrasonography may be considered complementary to urography in cases of non-functioning kidney, when the urographic filling device defect is uncertain and in the differentiation between the pyelic or parenchymal origin of the tumour.

Delayed CT in acute renal infection.

CT scans of the kidneys obtained approximately 3 hours after contrast administration often reveal useful information in patients with renal infections. In this article, we discuss three main features of these delayed scans. Feature 1 shows a nephrogram replacing a variable portion of the low density areas present in the early enhanced phase. The nephrogram can be streaky, band-like, cone or horseshoe-shaped; Feature 2 exhibits a focal staining or a hyperdense rim surrounding microabscesses and macroabscesses; Feature 3, very rare, is characterized by hyperdense areas located far from the lesions detected on early scans. These features make it possible to better define the actual extent of infection and the presence of the edema, improving diagnostic confidence.

Problematic renal masses in ultrasonography and computed tomography.

The diagnosis of renal masses is based upon the contribution of ultrasonography (US) and computed tomography (CT), which enable the recognition of these lesions with high diagnostic accuracy. However, a number of diagnostic difficulties exist in the definition of the nature of the mass, both for cystic and solid lesions, and to a lesser extent in the identification of the mass. "Complicated" cystic masses, such as calcified cysts, hemorrhagic cysts, inflammatory cysts, abscesses, and cystic tumors may be difficult to diagnose with US and sometimes with CT. CT is helpful in most of these cases because it enables the evaluation of the calcifications and the density of the fluid content. CT is also helpful in cases of cystic tumors because it shows the enhancement of septae within the masses. Problems with solid masses are the identification of small renal tumors and the definition of the benign or malignant nature of the mass. Although both techniques enable the recognition of most tumors, even if small in diameter, they are still limited in defining the pathological structure of the tumor.

MRI appearance of the articular cartilage in the knee according to age.

To study the MR appearance of knee joint hyaline cartilage according to age, sex and body weight 120 subjects underwent MRI of the knee. Axial SE PD and T2, GE T1 and GE-MTC sequences, as well as coronal SE T1 and sagittal SE PD and T2 sequences were used. Thickness, surface, signal intensity and visibility of the patellar and femorotibial cartilages were investigated. As for cartilage thickness, a statistically significant difference was found between males and females in nearly all the measurement sites, the mean values being always higher in males. A statistically significant inverse correlation was found in males only, at the three load bearing regions of the medial femoral condyle. No significant correlation was demonstrated between the surface, the signal intensity and the trilaminar appearance of the cartilage and age, as well as body weight. The cartilage of the femoral condyles, the tibial plateaux and the patella showed a regular surface in 76%, 98% and 82% of cases respectively. The signal intensity was homogeneous in 88%, 98% and 82.5% of the cases. Mild focal inhomogeneities were seen in few cases. The visibility rate of the trilaminar appearance of cartilage was 85% for the femoral condyles, 70% for the patella, 13.5% for the tibial plateaux. GE sequence was the best sequence to evaluate cartilage thickness and signal intensity, while SE T2 sequence was the best sequence to depict the articular surface and, together with PD SE sequence, to visualize the trilaminar structure. The most relevant result of this study is the inverse correlation between cartilage thickness and age as well as body weight, mainly in males, in the three areas of greatest load (medial femoral condyle).