Imaging processing for CT angiography of the cervicocranial arteries: evaluation of reformatting technique.

PURPOSE: The aim of this study was to compare computed tomography angiography (CTA) sliding-thin-slab (STS) multiplanar reformatting (MPR), STS maximum intensity projection (MIP) and three-dimensional (3D) volume rendering (VR) reformatting techniques in the evaluation of cervicocranial arteries. MATERIALS AND METHODS: Twenty patients examined with multislice CT were included in this study. CTA images were reformatted as STS-MIP, STS-MPR and 3DVR in orthogonal planes and in the oblique-coronal plane. Images were evaluated in consensus by two radiologists, with a third radiologist to resolve discordances in grading image quality parameters. The Spearman correlation analysis was performed to compare results and to obtain the correlation between scores resulting from the evaluation of parameters considered with the different techniques used (STSMIP, STS-MPR and 3DVR). RESULTS: STS-MIP images were significantly superior to STSMPR images for all parameters considered (p<0.05). Obliquecoronal 3DVR images were significantly superior to obliquecoronal STS-MIP images in the evaluation of vertebrobasilar vessels (p<0.05); in all other cases, 3DVR images were equivalent to STS-MIP images. CONCLUSION: STS-MIP images should be the primary reformatting technique for CTA of the cervicocranial arteries in addition to viewing the source images; 3DVR images can play an important role after a previsional diagnosis is made on the STS-MIP images.

Chromatographic behaviour of peptides on a mixed-mode stationary phase with an embedded charged group by capillary electrochromatography and high-performance liquid chromatography.

Retention behaviour of biological peptides was investigated on a stationary phase bearing an embedded quaternary ammonium group in a C21 alkyl chain by both high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC). In HPLC experiments, variation of acetonitrile (ACN) content in the mobile phase showed that peptides are mainly separated by RP mechanism. The weak or negative retention factors observed as compared to C18 silica stationary phase suggested the involvement of an electrostatic repulsion phenomenon in acidic conditions. Comparison of HPLC and CEC studies indicated that (i) ion-exclusion phenomenon is more pronounced in HPLC and (ii) higher ACN percentage in mobile phase induce for some peptides an increase of retention in CEC, pointing out the existence of mechanisms of retention other than partitioning mainly involved in chromatographic process. This comparative study demonstrated the critical role of electric field on peptide retention in CEC and supports the solvatation model of hydrolytic pillow proposed by Szumski and Buszewski for CEC using mixed mode stationary phase in CEC.

[Thrombolytic therapy in myocardial infarction. Computerized tomography of encephalic complications]. / Terapia trombolitica nell'infarto del miocardio. Aspetti con Tomografia Computerizzata della complicanze encefaliche.

PURPOSE: To evaluate the CT findings of intracerebral hemorrhage in patients undergoing thrombolytic therapy for acute myocardial infarction and to correlate the type of intracerebral hemorrhage with clinical outcome. MATERIAL AND METHODS: We retrospectively reviewed the clinical records and CT scans of intracerebral hemorrhage on a total of 302 patients who underwent thrombolytic therapy for acute myocardial infarction at our institution from January 1996 to September 1999. In each patient we evaluated: the number, sites and size of hemorrhage, and the presence and severity of mass effect. The site of the hemorrhage was classified as intraparenchymal, intraventricular, subdural and subarachnoid. RESULTS: Six patients (2%, mean age 74, range 66-80) developed intracerebral hemorrhage. There was a total of 22 hemorrhages: 1 subdural hemorrhage, 6 subarachnoid, 11 intraparenchymal and 4 intraventricular. Excluding intraventricular hemorrhage, 14/18 hemorr-hages were located supratentorially. In five patients there was a fluid-blood level. Three patients had severe mass effect with midline shift. Symptoms presented within 24 hours from the administration of thrombolytic therapy in all patients. All the patients who died had a large hematoma with a severe mass effect and a severe midline shift at CT scan. In the remaining patients, the hematoma was of medium size and no mass effect was seen. CONCLUSIONS: The most common site of hemorrhage was supratentorial and intraparenchymal. Large volume intracerebral hemorrhage, multiple hemorrhages and mass effect with midline shift were associated with increased mortality. The most commonly observed finding was a fluid-blood level hematoma.

Transfusional hemochromatosis: quantitative relation of MR imaging pituitary signal intensity reduction to hypogonadotropic hypogonadism.

PURPOSE: To assess the relationship between magnetic resonance (MR) imaging pituitary signal intensity reduction in patients with transfusional hemochromatosis and the clinical manifestation of hypogonadotropic hypogonadism. MATERIALS AND METHODS: Pituitary MR imaging at 0.5 T was performed in 38 consecutive patients affected by secondary hemochromatosis and in 20 healthy volunteers. Serum ferritin levels were estimated in the affected population. Twenty (53%) of the 38 patients had hypogonadotropic hypogonadism diagnosed. Pituitary-to-fat signal intensity ratios were calculated from coronal gradient-echo (GRE) T2*-weighted MR images. The relationship between the quantitative reduction of the pituitary-to-fat signal intensity ratio and the clinical manifestation of pituitary dysfunction was assessed in the affected population. Signal intensity reduction in the anterior lobe of the pituitary gland was also correlated with the serum ferritin level. RESULTS: The degree of reduction of the pituitary-to-fat signal intensity ratio correlated with the presence of hypogonadotropic hypogonadism, with a sensitivity of 90%, a specificity of 89%, and an overall accuracy of 89%. In addition, the reduction of pituitary signal intensity was greater in patients with higher ferritin levels (r = -0.55, r(2) = -0.30, P <.001). CONCLUSION: The degree of signal intensity reduction, measured as the pituitary-to-fat signal intensity ratio for GRE T2*-weighted images, in patients with secondary hemochromatosis correlates with the severity of pituitary dysfunction.

MR imaging of the brain: findings in asymptomatic patients with thalassemia intermedia and sickle cell-thalassemia disease.

OBJECTIVE: The purpose of this study was to evaluate the spectrum of MR findings of the brain in asymptomatic patients affected with thalassemia intermedia or sickle cell-thalassemia disease to prevent brain damage by identifying patients at risk for stroke so that transfusional or pharmacologic treatment could be implemented. SUBJECTS AND METHODS: Forty-one asymptomatic patients who were younger than 50 years and were affected by minor hemoglobinopathies underwent MR imaging of the brain. Ischemic lesions were classified as small, medium, or large and as single or multifocal. Atrophic changes were graded subjectively as mild, moderate, or severe. A grade of brain damage was assigned to every patient. The frequency and severity of brain damage were correlated with the number of sickle-cell crises per year, hemoglobin level, sickling hemoglobin level, platelet count, sex, and age. RESULTS: Of the patients with thalassemia intermedia, 37.5% showed asymptomatic brain damage, and 52% of those with sickle cell-thalassemia disease showed asymptomatic brain damage. In the thalassemia intermedia group, atrophy was always mild and ischemic lesions were generally small (25%) and single (25%). Among the patients with sickle cell-thalassemia disease, 24% had small, 16% had medium, and 12% had large ischemic lesions. Multifocal lesions were twice as common in the patients with sickle cell-thalassemia disease (20%) as in those with thalassemia intermedia (12.5%). Only in the patients with thalassemia intermedia did the frequency of brain damage increase with age. Moreover, brain damage inversely correlated with hemoglobin level in patients with thalassemia intermedia but not in those with sickle cell-thalassemia disease. Brain damage was more severe in patients with sickle cell-thalassemia disease who had more crises per year. CONCLUSION: This study suggests that patients with thalassemia intermedia and those with sickle cell-thalassemia disease may have asymptomatic brain damage. Our results suggest that MR imaging is useful in identifying patients at risk for stroke so that they can be treated with transfusional or pharmacologic therapy.

Reversible MRI abnormalities in an unusual paediatric presentation of Wernicke's encephalopathy.

BACKGROUND: We report an unusual paediatric presentation of acute Wernicke's encephalopathy in a 12-year-old boy affected by chronic gastrointestinal disease. MRI demonstrated, in addition to the typical diencephalic and mesencephalic signal abnormalities on T2-weighted images, enhancement of the mammillary bodies and the floor of the hypothalamus. MATERIALS AND METHODS: Following parenteral administration of thiamine for 4 days, the patient recovered from his neurological deficits and on follow-up enhanced MRI 1 month later, no signal abnormalities were found nor was there diencephalic or mesencephalic atrophy, as is usual in the chronic phase of the disease. RESULTS: MRI provides crucial information in the diagnosis of Wernicke's encephalopathy, either in the acute or chronic phases of the disease. CONCLUSION: Our report provides an additional clue for recognition of the acute phase of the disease; enhancement of the floor of the hypothalamus has not previously been described despite its recorded involvement at autopsy.

[Cerebral vascular autoregulatory dysfunction. Neuroradiologic aspects]. / Encefalopatia da disreattività vasoregolatoria cerebrale. Aspetti neuroradiologici.

PURPOSE: We report the neuroimaging findings in a group of systemic disorders with a common pathophysiological pattern of derangements in cerebral vascular autoregulatory mechanism producting potentially reversible brain lesions. MATERIAL AND METHODS: We reviewed the brain CT and MR examinations of 14 patients with clinical diagnosis of vasculopathy not related to atherosclerosis or cardiogenic embolism. The patients were admitted at the onset of neurologic deficit and were affected with one of the following systemic disorders: thrombotic thrombocytopenic purpura (TTP, 6 cases), uremic encephalopathy (4 cases), eclampsia (2 cases), 1 chronic renal failure from systemic lupus erythematosus and 1 cyclosporin neurotoxicity. All patients underwent neuroimaging follow-up within 7-20 days of the onset of neurologic deficit and the start of anti-edema therapy. RESULTS: CT and MR findings were characterized by cortical-subcortical or deep brain lesions related to edema. Ten patients presented bilateral lesions, which were symmetric in 4 cases. Edema resolution was demonstrated on follow-up examinations after therapy in 4 patients (2 with eclampsia, 1 with TTP and 1 with uremic encephalopathy). The lesions showed no signs of regression in 10 patients. CONCLUSIONS: Brain lesions with a common pathogenesis from derangements in vascular autoregulatory mechanism--i.e., not due to atherosclerosis or cardiogenic embolism--should be properly and promptly recognized because they can be reversible and readily treatable.

MR imaging technique for the diagnosis of pituitary iron overload in patients with transfusion-dependent beta-thalassemia major.

To identify the optimal MR imaging technique for diagnosing pituitary iron overload, we compared spin-echo and gradient-echo MR imaging with measurements of pituitary T2 relaxation times in 30 patients with secondary hemochromatosis due to transfusion-dependent beta-thalassemia major and in 10 healthy volunteers. We found that the optimal MR imaging technique to evaluate pituitary iron overload is the gradient-echo T2*-weighted technique, as it best demonstrated signal reduction in the anterior lobe of the pituitary gland.

Magnetic resonance findings in scuba diving-related spinal cord decompression sickness.

Scuba diving is associated with risk of severe decompression sickness (DCS type II), which results from rapid reduction of the environmental pressure sufficient to cause the formation into tissue or blood of inert gas bubbles previously loaded within tissues as a soluble phase. DCS type II constitutes a unique subset of ischemic insults to the central nervous system (CNS) with primarily involvement of the spinal cord. Ten patients with diving-related barotrauma underwent neurologic examination. Two of them presented progressive sensory and motor loss in the extremities at admission and were presumed affected by spinal cord DCS. Magnetic resonance imaging (MRI) demonstrated abnormalities in the white-matter tracts of the spinal cord in these patients, in each case corresponding to an area of the cord believed to be clinically involved. After a course of therapeutic recompressions, one patient was able to stand and walk a short distance, and MRI revealed a decreased extension of areas of spinal cord abnormalities. MRI has proved to be reliable in the detection of pathologic changes of spinal cord decompression sickness that were previously undetectable by other neuroimaging methods and also has proved to be useful in the follow-up during therapeutic hyperbaric recompressions.

[Server World-Wide Web on the Internet for the provision of clinical cases and digital radiologic images for training and continuing education in radiology]. / "Server World-Wide Web" su Internet per la distribuzione di casi clinici e immagini radiologiche digitali di supporto alla formazione e all'aggiornamento professionale nella radiologia.

The Internet, as a global computer network, provides opportunities to make available multimedia educational materials, such as teaching files and image databases, that can be accessed using "World-Wide Web" client browser to provide continuing medical education. Since August, 1995, at the Institute of Radiology-University of Palermo, we developed a World-Wide Web server on the Internet to provide a collection of interactive radiology educational resources such as teaching files and image database for continuing medical education in radiology. Our server is based on a UNIX workstation connected to the Internet via our campus Ethernet network and reachable at the uniform resource locator (URL) address: http:/(/)mbox.unipa.it/approximately radpa/ radpa.html. Digital CT and MR images for teaching files and image database are downloaded through an Ethernet local area network from a GE Advantage Windows workstation. US images will be acquired on-line through a video digitizing board. Radiographs will be digitized by means of a Charge Coupled Device (CCD) scanner. To set up teaching files, image database and all other documents, we use the standard "HyperText Markup Language" (HTML) to edit the documents, and the Graphics Interchange Format (GIF) or Joint Photographic Expert Group (JPEG) format to store the images. Nine teaching files are presently available on the server, together with 49 images in the database, a list of international radiological servers, a section devoted to the museum of radiology hosted by our Institute, the electronic version of the Journal Eido Electa. In the first 12 months of public access through the Internet, 12,280 users accessed the server worldwide: 45% of them to retrieve teaching files; 35% to retrieve images from the database; the remaining 20% to retrieve other documents. Placing teaching files and image database on a World-Wide Web server makes these cases more available to residents and radiologists to provide continuing medical education in radiology.