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Rationale and Objectives: To assess the accuracy of logistic regression (LR) and artificial neural networks (NN) in the diagnosis of calvarial lesions using computed tomography (CT) and to establish the importance of the different features needed for the diagnosis., Methods: One hundred sixty-seven patients with calvarial lesions as the only known disease were enrolled. The clinical and CT data were used for LR and NN models. Both models were tested with the leave-one-out method. The final results of each model were compared using the area under receiver operating characteristic curves (Az)., Results: Of the lesions, 73.1%, were benign and 26.9% were malignant. There was no statistically significant difference between LR and NN in differentiating malignancy. In characterizing the histologic diagnoses, NN was statistically superior to LR. Important NN features needed for malignancy classification were age and edge definition, and for the histologic diagnoses matrix, marginal sclerosis, and age., Conclusion: NNs offer wide possibilities over statistics for the study of calvarial lesions other than their superior diagnostic performance.

Rationale and Objectives: The authors analyzed the accuracy of diagnostic features used by an artificial neural network compared with logistic-regression analysis in the diagnosis with computed tomography (CT) of calvarial eosinophilic granuloma., Materials and Methods: Thirty-one of 167 patients with calvarial lesions were found to have eosinophilic granuloma. Clinical and CT data were used for logistic-regression and neural network models. Both models were tested by using the leave-one-out method. The final results of each model were compared by means of the area under the receiver operating characteristic curve (Az)., Results: Identification of eosinophilic granuloma was significantly more accurate with the neural network than with logistic regression (Az = 0.9846 +/- 0.0157 [standard deviation] vs 0.9117 +/- 0.0373) (P = .001). The most important diagnostic features identified with the neural network were patient age and marginal sclerosis. For logistic regression, the most important features were age, shape, and lobularity., Conclusion: The neural network is a useful tool for analyzing the features of calvarial eosinophilic granuloma. Age and marginal sclerosis are important diagnostic features.

Osteoid osteoma (OO) is a benign skeletal neoplasm. Twenty-eight patients with proven OO were studied with MRI regarding soft tissue involvement which was diagnosed when high proton-density and T2-weighted signal intensity and low signal intensity on T1-weighted images were found close to bone. Most tumors were located in the femur and tibia; 6 cases diaphyseal, 12 metaphyso-diaphyseal, and 10 epiphyseal. In relation to the cortex, 15 were located centrally or in its outer margin. Soft tissue involvement was found in 15 patients (53.6 %). A statistical relationship was found between soft tissue involvement and the tumor's location with regard to the cortex, being more frequent in peripherally located tumors. Therefore, soft tissue involvement is a frequent finding in peripherally located OO.

We present a patient with nodular regenerative hyperplasia of the liver (NRH) and portal vein absence studied with CT, MR imaging, and MR angiography. The most striking feature was exuberant hemorrhoids due to a giant hepatofugal inferior mesenteric vein. A relationship between unbalanced portal blood flow and nodular regenerative transformation of the liver is suggested in this patient.

Pulmonary torsion is a serious complication consisting of the rotation of the pulmonary parenchyma upon its vascular pedicle. Torsion is usually related to lung surgery and may lead to death. Early diagnosis allows for the rapid treatment that is essential for preventing death and decreasing associated complications.

Objectives: Iopentol (Nycomed Imaging AS, Oslo, Norway) and iopromide (Schering AG, Berlin, Germany) are low-osmolar, non-ionic, iodinated contrast media (CM) used in abdominal CT examinations. The intravenous safety profile and radiological efficacy of iopentol and iopromide were studied in 518 patients. Specifically, frequency of adverse events (AEs), subjective change in quality of diagnostic information, and quantitative enhancement characteristics were compared., Materials and Methods: A prospective, double-blind, randomized, multicentre, parallel-group study was conducted at 8 hospitals. Patients received 100 ml of either iopentol 300 mg I/ml or iopromide 300 mg I/ml., Results: The incidence of patients with AEs was statistically significantly lower in the iopentol group compared to the iopromide group (2.3% vs. 8.9%, p < 0.001). Discomfort was frequent in both groups (44.8% vs. 49.4%, p = 0.33), sensation of heat and warmth being most common. Overall, diagnostic information was similar in both groups. Both CM gave high percentages of examinations rated as optimal (87.1% vs. 90.5%, p = 0.34) and in which diagnostic confidence was increased (87.5% vs. 91.1%, p = 0.22). No significant differences between the two CM were found concerning quantitative enhancement characteristics., Conclusions: In this study iopentol was significantly safer than iopromide for contrast enhanced CT examination of the abdomen. Radiological efficacy was similar with both CM.

There is no doubt that radiologists play an increasingly important role in the detection of focal liver lesions, and in the evaluation of persistent or recurrent malignant disease after treatment. The characterization of focal liver lesions depends on the clinical integration of the information generated by different radiologic techniques. Most often, MR imaging is quite effective in liver tumor characterization. Our purpose is to provide an overview of the MR characteristics of the most commonly encountered liver tumors and their differential diagnosis, with the most accepted reliable proof of the lesion type in a clinical environment. Radiologists must know the level of confidence they can reach in a given diagnosis, and the influence that this diagnosis has in the patient's management. With this knowledge, radiologists decide whether to leave or follow-up the lesion, perform tissue samples, or carry out therapeutic procedures.

Nodular regenerative hyperplasia (NRH) of the liver is a condition characterized by multiple monoacinar regenerative nodules in the absence of fibrous septa. When these nodules become confluent they may be seen with sonography or CT. The appearance of these pseudotumoral pattern of NRH has been scarcely described with MRI. We present the imaging findings of five patients with NRH and a pseudotumoral form at sonography. Sonography depicted hyperechoic lesions in four patients and hypoechoic lesions in another. Computed tomography showed hypodense lesions with little contrast enhancement in two patients. Three patients showed subtle focal liver lesions on MRI: isointense in one, mildly hypointense in another, and minimally hyperintense in a patient with siderosis. The dynamic behavior at MRI was similar to the normal liver parenchyma. Hyperechoic lesions on sonography or hypodense lesions on CT, barely or not seen on MRI, can be indicative of NRH in an appropriate clinical setting.

Magnetic resonance (MR) field strength is one of the key aspects to consider when purchasing MR equipment. Other aspects include the gradient system, coil design, computer and pulse sequence availability, purchase cost, local reimbursement policies, and current opinion within the medical community. Our objective here is to evaluate the decision-influencing aspects of the MR market, with a focus on some specific areas such as high resolution studies, examination times, special techniques, instrumentation, open design magnets, costs and reimbursement policies, academic and industrial interests, contrast media, clinical efficacy, and finally, clinicians' preferences. Certainly the advantage of high-field is a higher signal-to-noise ratio and improved resolution. With a high-field unit, higher spatial resolution images and higher temporal resolution images can be obtained. Typical imaging times needed to produce clinically diagnostic images are about 3 times longer at 0.1 T than at 1.0 or 1.5 T. High-field-related advanced techniques, such as functional imaging, spectroscopy and microscopy, may become clinically useful in the near future. As long as there is an unlimited demand for MR examinations, it appears financially profitable to run a high-field system, despite the associated higher costs. However, if demand for MR becomes saturated, low-field systems will cause less financial strain on the reimbursement organisation and service provider. Recent emphasis on cost containment, the development of interventional techniques, the increased use of MR for patients in intensive care and operating suites, the deployment of magnets in office suites, and the development of new magnet configurations, all favour the supplementary use of low-field systems. Hence, MR units of all field strengths have a role in radiology.

Rationale and Objectives: The authors describe a method to differentiate healthy from cirrhotic livers by the analysis of their behavior after paramagnetic contrast administration on magnetic resonance imaging., Methods: A dynamic single-slice spoiled-gradient recalled echo magnetic resonance imaging after contrast administration was performed on 67 patients (36 healthy livers and 31 cirrhotic livers). Three parametric images (averaged-enhancement, maximum-enhancement, and maximum-velocity) were reconstructed from the temporal dynamic images. Liver values were quantified by means of a region-of-interest procedure., Results: Relative averaged-enhancement and maximum-enhancement values were significantly different ( P < 0.05) between cirrhotic and normal livers. There was a significant correlation between the parametric values and the Child-Turcotte index of hepatic chronic insufficiency (P < 0.05)., Conclusions: Parametric images allow characterization of the signal-versus-time pixel-by-pixel variations in dynamic magnetic resonance imaging. The averaged-enhancement and maximum-enhancement values can be used to differentiate healthy from cirrhotic livers with accuracy. The higher values found in cirrhotic patients may reflect an overall increase in the amount of extracellular contrast present with respect to healthy livers. The degree of liver brightness in cirrhotic patients probably is related to an increased amount of interstitial space, an indirect measurement of hepatic necrosis.

Background: Peristaltic motion is an omnipresent source of degradation in abdominal magnetic resonance (MR) imaging by blurring images and producing ghost artifacts that can mask or mimic lesions. The objective of this study was to select an effective and easy-to-administer drug to provide consistent reduction of peristaltic motion artifacts on MR images., Methods: One hundred forty-eight adult patients with MR examinations of the abdomen were enrolled in a prospective, single-blind comparative study. Four groups were defined: (a) no-drug control group (n = 35), (b) 1 mg of intravenous (IV) glucagon (n = 19), (c) 20 mg of IV butylscopolamine (n = 28), and (d) 20 mg of oral dicyclomine (n = 66). All patients received high-density barium sulphate as a negative oral contrast medium. Quantitative image analysis was performed with operator-defined region-of-interest measurements of signal intensity. Gastrointestinal noise was measured outside the patient at the posterior part of the left hemiabdomen along the phase-encoding direction on a short inversion time inversion recovery (STIR) sequence., Results: Treatment groups showed reduced gastrointestinal noise (p < 0.01). When compared with the control group, IV butylscopolamine (p < 0.05) and oral dicyclomine (p < 0.05) significantly reduced gastrointestinal noise, whereas glucagon did not., Conclusion: Anticholinergic drugs significantly reduced the intensity of ghost artifacts on MR imaging of the abdomen. Twenty milligrams of oral dicyclomine is an effective and safe alternative to more expensive and parenterally administered drugs such as glucagon and butylscopolamine.

Orally administered chloral hydrate is the most widely used sedative in children undergoing MRI. We compared intermediate- and high-dose oral chloral hydrate in 97 consecutive children undergoing MRI in a prospective, controlled, double-blind, randomised clinical trial. There were 50 girls and 47 boys, mean weight (+/- SD) 14.7 +/- 6.4 kg, and mean age 38 +/- 31. The children were randomly allocated to receive chloral hydrate syrup either 70 mg/kg (group A, n = 50) or 100 mg/kg (group B, n = 47). These two groups were not significantly different in sex, weight, age, diagnosis or ambulatory medication. The mean initial dose (+/- SEM) was 64 +/- 2 mg/kg for group A and 93 +/- 2 mg/kg for group B. Because adequate sedation was not achieved, 14 patients in group A and 6 in group B required a second dose, giving a mean total dose of 70 +/- 2 mg/kg for group A and 96 +/- 2 mg/kg for group B. The percentage of successful examinations after the initial dose (A: 64%, B: 87%; p < 0.05) and the total dose (A: 92%, B:100%; p = 0.14) was higher in group B. Significant differences were found for the time of onset of sedation (A:28 +/- 2 min, B: 21 +/- 1 min; p < 0.05), but not for the time to spontaneous awakening after the completion of the examination. The rate of adverse reactions was similar (A: 20%, B: 21%; p = 1.00). We conclude that high-dose oral chloral hydrate improves the management of children undergoing MRI.

The objective of this investigation was to assess the effectiveness of four iodinated X-ray contrast media for abdominal computed tomographic (CT) examinations. Fifty-three patients were prospectively randomized to receive iohexol 300 mgI/ml (100 ml, n = 17), ioversol 320 mgI/ml (100 ml, n = 13), iopromide 300 mgI/ml (75 ml, n = 12), or iopentol 300 mgI/ml (100 ml, n = 11) to perform a dynamic contrast-enhanced abdominal CT. Image-enhancement profiles for the liver, aorta, and vena cava were studied. The maximum liver enhancement, the time to maximum liver enhancement, and the area under the hepatic enhancement-time curve (AUC) were determined for each examination. Liver-enhancement profile showed significant differences between the four contrast agents, with lower values for iopromide towards the final part of the CT examination (P < 0.05). Hepatic peak values were attained earlier for iopromide, although these were lower than those produced by any other of the agents evaluated in this study. Iopentol produced fast and intense hepatic peaks. Consequently, high AUC values were obtained with iopentol, low values were obtained with iopromide (P < 0.05), although this can be explained by the lower amount of contrast medium contained in the commercial vial and administered to the patient (75 ml vs 100 ml). When normalized to a 100 ml dose, the AUC value for iopromide becomes even higher than the average of the other three agents (P = 0.05). Ioversol, although available and administered as a more concentrated solution (320 mg/ml), was comparable to the less concentrated iohexol and iopentol (300 mgI/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Purpose: To graphically display the time dependency of contrast enhancement of liver tumors at examination with dynamic magnetic resonance (MR) imaging., Materials and Methods: A temporal reconstruction image was generated by obtaining a line of interest drawn on a single image through the liver and the tumor and reformatted over a sequence of temporal images. This calculated image expressed the temporal evolution of the line, including nontumoral liver and tumor, with regard to three variables: signal intensity, enhancement, and velocity. This allowed a visually integrated analysis of 95 hepatic lesions studied with dynamic single-section MR imaging after contrast material administration., Results: Temporal reconstruction images were obtained for all the dynamic studies. Five patterns of enhancement based on signal intensity and velocity variations coupled with morphologic information were found: wall, diffusion, moderate enhancement, marked progressive, and early intense patterns., Conclusion: Temporal reconstruction of liver tumors after contrast material administration can be used to analyze, describe, and report the dynamics of lesion enhancement with morphologic and temporal resolution.

Thirty-nine patients with renal calculi were retrospectively studied with magnetic resonance (MR) imaging and an ultrasound (US). All patients were examined as part of a research project for imaging evaluation of complications of extracorporeal shock wave lithotripsy. Twelve of the patients showed lymph node enlargement in the retroperitoneal perivascular space. Adenopathies were visualized by MR imaging but not with US: The presence of large lymph nodes was associated with urinary, renal parenchymal, or stone infection. When large lymph nodes are found in the retroperitoneal perivascular space in patients with lithiasis, urinary tract infection must be assumed as the cause of these adenopathies.

Rounded atelectasis is a rare form of lung collapse whose X-ray appearance can be confused with that of tumors, especially nodular forms. We studied 14 such lesions with computerized tomography, finding that all were rounded and subpleural, specifically in the thickened pleura visceralis. The radiological sign that was most useful for diagnosis was the arc of the proximal vessels in the direction of the lesion. Such an arc was present in all the cases we reviewed. Other radiological signs such as brightness of the surrounding parenchyma, loss of volume in the affected lobe and the presence of air bronchogram were found in 10, 7 and 7 patients, respectively. When the X-ray appearance clearly indicates a diagnosis of rounded nodular atelectasis, we recommend that no additional diagnostic procedure be made. Three lesions in our sample were studied by magnetic resonance, which revealed the characteristic hypointense curves in all sequences done on 2 patients. The usefulness of computerized tomography in the diagnosis of this entity relegates magnetic resonance to a second plane.

Sedation is routinely required for successful Magnetic Resonance imaging in infants and children. Five hundred and ninety-six paediatric patients (270 female and 326 male, age (mean +/- SD) 41 +/- 30 months and weight 14.8 +/- 6.5 kg) entered an open, non-comparative, prospective study to assess oral chloral hydrate sedation in a large and homogeneous paediatric population undergoing Magnetic Resonance imaging. Chloral hydrate syrup 70 mg/ml was administered 20-40 min prior to the procedure. Effective sedation was reached in 94.1% with a total dose (mean +/- SEM) of 68 +/- 1 mg/kg (range 20-170 mg/kg). Statistical analysis of sedation failures vs. successful examinations after the total dose showed significant differences for dose (62 +/- 4 vs. 69 +/- 1 mg/kg; P < 0.05), age (64 +/- 7 vs. 40 +/- 1 months; P < 0.001) and weight (19.8 +/- 1.5 vs. 14.5 +/- 0.0 kg; P < 0.001). Effectiveness fell to around 80% in children with encephalic white matter alterations, medullary tumours or syringohydromyela (P = 0.07). The mean time of onset of sedation was 26 +/- 1 min, and the mean time to spontaneous awakening after the completion of the Magnetic Resonance examination was 38 +/- 2 min. Fifty-nine children (9.9%) experienced adverse reactions, with nausea and vomiting being the most common (n = 41), followed by nervousness and unusual excitement (n = 6). Discriminant function analysis identified age and total dose as the quantitative variables helping to differentiate between sedation failures and satisfactory examinations (sensitivity = 0.73, and specificity = 0.61; r = 0.20, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Intrauterine diagnosis of perinatal hemochromatosis is difficult. Noninvasive detection of hepatic iron deposition is crucial. We report the first case diagnosed intrauterine with magnetic resonance imaging (MRI). By visual analysis, if the fetal liver is less intense than maternal or fetal fat signal for T2* gradient echo image, hemochromatosis should be suggested.

To characterize the relationship between findings on magnetic resonance (MR) images and histologic changes in chronic liver disease, a prospective study was performed in 100 patients with chronic hepatitis and cirrhosis and 28 healthy subjects. Biopsy specimens, obtained in all patients before MR imaging, were evaluated with the histologic activity (HA) index; MR images were obtained with short inversion time inversion-recovery (STIR) and spin-echo sequences. On STIR images, normal livers were iso-intense to fat. Significant differences (P < .001) existed between signal intensity of normal livers and that of diseased livers, which were brighter than normal livers on STIR images. The ratio of signal intensity of liver to that of fat on STIR images was associated with an HA index grouped by severity (P < .05): Patients with higher HA scores had a brighter liver. Signal intensity ratios on MR images were statistically significantly associated with periportal and lobular necrosis and portal inflammation. The signal intensity of liver on STIR images is associated with the degree of histologic severity in patients with chronic liver disease.

The aim of this paper is to study the pre-operative staging of renal tumours, comparing CT and MR, and the imaging criteria used, examining the diagnostic efficacy for each of them. Thirty-four tumours were obtained from 29 patients. All cases were studied with CT and MR. To measure diagnostic efficacy, both for each technique and the criteria used in 2 different readings, a diagnostic performance curve (DPC) is calculated. Neither CT nor MR show infiltration of renal capsule. With regard to perinephritic fat, fascia and adjacent organ invasion, both techniques lead to overstaging, mainly CT. When applying more conservative reading criteria, the results are much improved, specially in relation to CT, although results with MR continue to be more favourable. MR is better to study vascular invasion, providing no false results. Of 22 tumours undergoing surgery, first option was the correct staging in 14 tumour with CT and in 16 with MR. When selecting the best imaging technique to stage renal tumours, MR allows a better and simpler radiologic reading. Nevertheless, considering the high correlation between CT and MR, CT can be used more reliably in institutions where no easy access to a MR unit is available. Both CT and MR overstage renal tumours.

Proximal absence of the right pulmonary artery is an asymptomatic congenital anomaly that must be considered when a small lung is present. This report describes two cases in adults in which computed tomography and magnetic resonance imaging provided morphologic data and flow data leading to the diagnosis and obviating the need for more invasive procedures.

The magnetic resonance (MR) imaging features of Brodie abscess have not yet been fully evaluated. Ten patients with Brodie abscess, eight of long bone and two of vertebra, were studied with MR imaging. Long bone abscess had a characteristic "target" appearance with four layers: (a) a center with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR (short-inversion-time inversion recovery) images, (b) an inner ring isointense to muscle on T1-weighted images and with high signal intensity on T2-weighted and STIR images, (c) an outer ring hypointense on all images, and (d) a peripheral halo hypointense on T1-weighted images. In six of eight cases, a soft-tissue mass was found. The two vertebral abscesses had a less specific appearance, with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR images. Only the peripheral halo was clearly identified in both cases.

In the Sturge-Weber syndrome facial venous and leptomeningeal angiomas are associated. We studied 14 consecutive cases with clinical and radiological evaluations [computed tomography (CT) and magnetic resonance imaging (MRI)]. Radiological studies demonstrated the extent and patency of the leptomeningeal angiomatous malformation, the degree of parenchymal atrophy, the presumed ischemic changes affecting the gray and white matter, the presence and extent of cortical calcifications, the prominence of the choroid plexus, the parenchymal venous anomalies, and the diploic prominence in the affected side. The white matter alterations, being greater, the extent of lobar involvement, and the degree of parenchymal atrophy all correlated with the patient's clinical status being poorer. MRI is more efficient in the detection of the radiological findings related to the clinical status: seizure control, degree of psychomotor development and hemiparesis. Therefore, MRI is the imaging modality of choice in the diagnosis of these patients.

Hepatic undifferentiated mesenchymal sarcoma is a rare pediatric malignant neoplasm. We present three children, aged 7, 8, and 12 years, with this tumor. Clinical presentation was abdominal pain, palpable mass, asthenia, anorexia, and weight loss. One had jaundice. All three lesions were detected on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI). MRI localized the lesions more accurately than the other methods, with good resectability correlation. On MRI, these tumors were markedly hyperintense on long TR/TE spin-echo (SE) and short-time inversion recovery (STIR) sequences. This was due to the cystic areas with myxoid material and necrosis. The internal separations were hypointense on these sequences. On short TR/TE SE sequences the lesions presented a fibrous pseudocapsule (two cases), and internal hyperintense areas representing hemorrhage (two cases). MRI also detected vascular invasion (one case), biliary obstruction (one case), and hilar adenopathies (one case). The combination of hemorrhage (hyperintense on short TR/TE SE) and cystic or myxoid components (markedly hyperintense on long TR/TE SE and STIR sequences) is common in this tumor.

Sedation is frequently required in children undergoing magnetic resonance imaging (MRI). 172 Paediatric patients (82 female and 90 male, age 42 +/- 26 months, weight 14.7 +/- 5.6 kg) entered an open, non-comparative, prospective study to assess the utilization of oral chloral hydrate. Chloral hydrate syrup (70 mg/ml) was administered 20-30 min prior to the procedure. Effective sedation was reached in 80.3% with an average initial dose of 55 mg/kg and in 93.6% with an average total dose of 65 mg/kg. Significant differences in effectivity were correlated with the dose (54 +/- 11 mg/kg in failure cases versus 66 +/- 16 mg/kg in effective cases; p < 0.05) and diagnosis (effectivity falls to 62.5% and 76.0% in children with medullar tumours and encephalic white matter alterations, respectively; p < 0.01). Average sleep induction time was 30 +/- 19 min, and average duration of sleep was 62 +/- 24 min. Adverse reactions occurred in 4.7%, with nausea, vomiting and stomach pain being the most common side-effects (3.5%). Multivariate statistical analysis selects total dose and age into the discriminant function, with a 100% relative percentage of correct classification. A simple method for optimizing the chloral hydrate dose in children is proposed: the dose in mg/kg is calculated as half the age in months + 50.

Sturge-Weber syndrome is a neurocutaneous syndrome that includes facial and leptomeningeal angiomas. Imaging findings include cerebral lobar atrophy, brain calcifications, choroid plexus enlargement, cranial diploë prominence, and venous abnormalities. We compared the efficacy of CT and MR imaging in making the diagnosis in 14 consecutive patients. CT, with and without contrast enhancement, was performed in all patients, and 11 of the 14 had MR imaging (eight before and after administration of IV gadopentetate dimeglumine). MR imaging was better than CT in showing the extent and degree of brain parenchymal atrophy, the presumed ischemic changes affecting the gray and white matter, and the cranial diploetic prominence on the affected side. MR imaging after contrast administration permitted a better evaluation of the extent and patency of the leptomeningeal angiomatous malformation and the parenchymal venous anomalies. CT was better than MR imaging in showing the presence and extent of cortical calcifications. Enhanced CT and MR imaging were equal in evaluating the prominence of the ipsilateral choroid plexus. Our experience indicates that contrast-enhanced MR imaging is the method of choice in the diagnosis of Sturge-Weber syndrome. Unenhanced CT should be used only if MR findings are normal, to exclude the presence of intracranial calcifications.

CT, MRI and neurological features of 27 children with tuberous sclerosis were prospectively compared. Imaging studies were positive in 92.5% of cases. CT was more useful in detecting subependymal nodules, while MRI showed the number and location of cerebral cortical and subcortical lesions more accurately. Cortical lesions in the cerebellar hemispheres were present in 26% of patients. Gadolinium-DTPA used in 10 patients showed slight enhancement of the subependymal lesions in 80% of cases, probably representing active lesions with alteration of the blood-brain barrier. None of the cortical and subcortical lesions enhanced. Giant-cell astrocytomas were detected in 5 patients, the postcontrast CT and MRI studies improving their assessment. Unlike subependymal nodules, all tumors showed marked enhancement regardless of their size. Seizures were present in 96% of patients, mostly beginning before 1 year of age. There was no clear relationship between the radiological features and the neurological evolution of these patients. Therefore, it is not possible to establish a clinical prognosis based on the radiological findings. MRI is the procedure of choice in the diagnosis of tuberous sclerosis. When pre and postcontrast MRI are negative, CT is used to exclude small calcified subependymal nodules. MRI follow-up is required only when tumoral development is clinically suspected.

We report a patient with alcoholic cirrhosis presenting with ascites, jaundice and malaise. Linear calcifications on the portal area were seen in the plain film of the abdomen. Computed tomography confirmed the presence of calcification of the portal vein wall and discovered lesions highly suggestive of diffuse multinodular hepatocarcinoma. We emphasize the rarity of portal vein calcification in patients with portal hypertension secondary to hepatic cirrhosis and hepatocarcinoma.

CT and MRI were used in a prospective study of the central nervous system (CNS) manifestations in 41 consecutive children with neurofibromatosis type 1 (NF-1). Gadolinium-DTPA was used in 15 patients. MRI was more effective than CT in delimiting the extension of the optic pathway glioma and in evaluating associated cerebral malformations. MRI visualized lesions generally undetected by CT, in the form of iso- or hyperintense foci with respect to the cerebral cortex in T2-weighted sequences. Well-delimited lesions of high signal intensity were observed in the globus pallidus (22 cases), the internal capsule (6 cases), corpus callosum (2 cases), anterior commissure (1 case) and semioval center (2 cases). Poorly defined hyper- or isointense areas were also observed affecting the cerebellar white matter (21 cases) and brain stem (17 cases). None of these lesions showed Gadolinium-DTPA enhancement, and were of no clinical significance. MRI has displaced CT in the initial diagnosis of patients with NF-1. Periodic annual MRI controls are only justified in patients with MRI changes to evaluate the progression or stabilization of the lesions.

Of 167 patients with abdominal hydatidosis, 29 showed a total of 36 hydatid cysts in which ultrasound demonstrated an overall echogenic appearance. The following ultrasound characteristics of an abdominal mass suggest the diagnosis of hydatid cyst: round or oval shape, well-defined borders, partial wall calcification, peripheral cystic structures, internal echogenic linear formations, snow storm and/or hyperechogenic internal echo pattern, and posterior acoustic enhancement. A comparative study with computed tomography has also been carried out in 10 of these cysts. Pathologic correlation in most cases allows us to postulate that this appearance represents an overly mature, probably ruptured, hydatid cyst.

We report a patient with highly malignant primary centroblastic lymphoma of the spleen (diffuse, large non-cleaved cell type). The tumor presented as splenomegaly due to a large mass containing diffuse punctuate calcifications. The latter have not been previously described as a radiological finding in this neoplasm.

A case of hepatic lipoma is reported. Since the sonographic (US), computed tomographic (CT), and magnetic resonance imaging (MRI) findings are characteristic, we believe more aggressive diagnostic procedures are not necessary.

Hydatid cyst rupture into the biliary tree may involve the common hepatic duct, lobar biliary branches, or the small intrahepatic bile ducts. We studied seven patients with hydatid cyst rupture into the larger bile ducts in whom sonography suggested the diagnosis. The findings included an echogenic cyst in all cases; intrabiliary hydatid material (echogenic or nonechogenic daughter vesicles and/or echogenic fragmented membranes) in six patients; and cyst-bile duct communication (observed in five cases as an interruption in the cyst wall adjacent to a bile duct). In the four cases in which CT was performed, both the cyst and high-density linear intrabiliary material were seen; in three patients, cyst wall rupture was detected. Sonographic and CT demonstration of a hydatid cyst in the liver together with intrabiliary hydatid material suggests rupture of the cyst into the biliary tree. In some cases, the diagnosis is reinforced by the detection of the communication itself.