Pre-operative classification of abdominal aortic aneurysms with spiral CT: the axial source images revisited

OBJECTIVE: The differentiation of supra-, juxta- and high infrarenal abdominal aortic aneurysms (AAA), which is essential for good surgical management, remains problematic. This prospective study assessed the value of highly overlapping vs. contiguous axial spiral computed tomography (CT) reconstructions in the pre-operative assessment of AAA. PATIENTS AND METHODS: Thirty-five patients with abdominal aortic aneurysms were studied with spiral CT (10 mm collimation, pitch 1). Axial reconstructions were performed at 2 and 10 mm increments and compared with surgical findings. Using each protocol, the aneurysms were classified as infra-, juxta- or suprarenal. Observers also assessed visualization of main and accessory renal artery origins and identification of other surgically relevant vascular anomalies. RESULTS: The 2 mm protocol correctly identified 29/31 infrarenal, 3/3 juxtarenal and 1/1 suprarenal aneurysms; two infrarenal aneurysms were overestimated as suprarenal. The 10 mm protocol correctly classified 25/31 infrarenal, 3/3 juxtarenal and 1/1 suprarenal aneurysms; five infrarenal aneurysms were overestimated as juxtarenal (n = 3) or suprarenal (n = 2) and one case was equivocal. Correct classification was thus 94% using the 2 mm protocol and 83% with the 10 mm protocol (P = 0.063). All 70 main renal artery origins were visualized with the 2 mm protocol, while the 10 mm protocol missed six (P = 0.03) The 2 mm protocol identified 10 accessory renal arteries, four of which were missed by the 10 mm protocol. Both protocols demonstrated five surgically relevant venous anomalies. CONCLUSION: Spiral CT with highly overlapping axial reconstructions correctly classified 94% of abdominal aortic aneurysms; overlapping reconstructions were particularly useful in differentiating high infrarenal from juxtarenal aneurysms.     

Dose distribution in conventional CT and spiral CT and on the topic of dose reduction with spiral CT

We retrospectively analyzed patterns of emergency room visits by patients with exacerbations of asthma from December 1995 through November 1996. A total of 591 episodes in 198 patients were reviewed. The average age was 35.8 years, ranging from 15 to 71. The largest number of visits occurred in September. The number of visits per year ranged from 1 to 22; the mean was 2.9 per year. In patients who were followed on a regular basis at our institution, serve attacks accounted for 7.1% of the total, compared with 21.6 percent at other hospitals or outpatient clinics. We suspect that this difference was related to differences in the use of inhaled steroids. At our institution, 89% of patients were taking inhaled steroids; at other hospitals or clinics, only 21% were taking inhaled steroids. Of the 198 patients, 33 fulfilled one of the following criteria: (1) endotracheal intubation for respiratory failure or respiratory arrest, (2) respiratory acidosis (pH < 7.35) without endotracheal intubation; 27% of those patients had been given a diagnosis of mild asthma before the acute exacerbation. We conclude that patient education and standard guidelines for treatment of asthma, are very important for appropriate management of asthma, to prevent exacerbations and asthma-related deaths.     

Detection of hepatic tumors: arterial-phase MR imaging versus spiral CT arteriography

BACKGROUND: Distinction between uncomplicated infective fasciitis and early necrotizing fasciitis can be extremely difficult without operation, yet the management and prognosis of both conditions depend greatly on early recognition and assessment of the extent of involvement. STUDY DESIGN: This was a prospective review of the utility of magnetic resonance imaging (MRI) in nine patients with suspected infective or necrotizing fasciitis treated at an academic medical center or a Veterans Administration hospital. RESULTS: Magnetic resonance imaging documented fascial inflammation, characterized by low intensity on T1-weighted images and high intensity on T2-weighted images, in all nine patients. Absence of gadolinium contrast enhancement on T1-weighted images reliably detected fascial necrosis in all six patients who required operative debridement. Magnetic resonance imaging was extremely useful in defining the extent of fasciitis and was more accurate in predicting necrosis or pyomyositis than was myoglobinuria or elevation of serum creatine kinase or lactate dehydrogenase. Operation was avoided in two patients without evidence of necrosis on MRI. One patient without evidence of necrosis, explored because of contradictory clinical findings, was confirmed at operation to have cellulitis without necrosis. CONCLUSIONS: Magnetic resonance imaging with gadolinium contrast accurately determines the presence of necrosis and the need for operation in patients with fasciitis of the lower extremity. Preoperative determination of the extent of involvement facilitates operative planning.     

Aortic dissection involving an aberrant right subclavian artery: CT and MR findings

Studies were conducted to determine the effect of environmental temperature on the susceptibility of Culex pipiens (L.) to Rift Valley fever (RVF) virus. Larval rearing temperature (13, 17, 19, or 26 degrees C) did not affect the susceptibility of adult female Cx. pipiens to infection with RVF virus. In contrast, the adult holding temperature after a viremic blood meal affected infection rates in females. Significantly fewer mosquitoes contained detectable virus when they were held at cooler temperatures, 13 degrees C (10%), 17 degrees C (20%), and 19 degrees C (41%) than at a warmer temperature, 26 degrees C (91%). For mosquitoes held at 13 degrees C and then switched to 26 degrees C, infection rates increased steadily with increased time at 26 degrees C. There was no effect on the ability to detect RVF virus in adult females that were subjected to cooler holding temperature (17 degrees C) after they were first held at warmer temperature (26 degrees C). The role of environmental temperature needs to be considered in studies on the epidemiology of arthropod-borne viruses.     

Renal artery evaluation: comparison of spiral CT angiography to intra-arterial DSA

Activin, a TGF-beta family member, and follistatin, an activin antagonist, encode signaling proteins which have been implicated in fundamental events in early vertebrate embryogenesis, such as mesoderm and neural tissue induction, and axial patterning. In this study I examine the roles of activin and follistatin in gastrulation in the chick. Activin betaB is found to be expressed at the base of the primitive streak prior to its formation, consistent with a role in streak induction. Follistatin has a more complex and dynamic expression in Hensen's node, and exhibits a left-right (LR) asymmetry. Antagonizing endogenous activin by ectopic application of follistatin protein causes the partial dissolution of the primitive streak and node, both morphologically and as assayed by loss of expression of molecular markers. This suggests that activin is necessary for the maintenance of streak morphology, and that follistatin may be involved in termination of the anterior progress of streak growth or in suppression of supernumerary streaks. Cell ingression through the node following follistatin application is normal, suggesting that it does not depend on the pit-like morphology of the wild-type node. Finally, follistatin temporally extends the asymmetric pattern of expression of HNF3-beta, this, as well as the stronger right-sided expression of follistatin, suggests a possible role in LR patterning.     

Increasing spiral CT benefits with postprocessing applications

This paper reviews the current and future role of various postprocessing tools for epidemiologically important diseases. It introduces a generic business system for diagnosis and treatment using Spiral CT. Postprocessing of Spiral CT data should become a routine part of radiological practice. As viewing moves from film to monitor displays, interactive postprocessing tools support evaluation of CT studies and will in some cases also improve diagnostic accuracy. Track-ball controlled browsing through the volume data may be performed on axial images or on multiplanar reformats (MPR). These tools can be expected to become an integral part of most CT evaluations in the near future. Already now, MPR are important adjuncts for most orthopaedic applications. Presently, three-dimensional (3D) displays are used mainly in orthopaedic and trauma patients. In CT angiography, 3D surface displays and maximum intensity projections are routine display modalities. New volume rendering techniques (VRT) with interactive parameter changes will make 3D imaging of soft tissues feasible as well. The key input factor for many postprocessing applications will be Spiral CT data sets with high z-axis resolution (subsecond scanning, thin collimation, overlapping image reconstruction) and optimised application of contrast media. The most important benefit of postprocessing is the communication with the referring physician since 3D representations are becoming increasingly important for treatment planning and control. Postprocessing services will become a key ingredient of a successful radiological practice. If radiology does not provide it, the other physicians will do it themselves. For treatment simulation, virtual surgical instruments and tissue motion models are still in their infancy and will keep software architects and physicians busy for the next decade of Spiral-CT.     

Functional spiral CT of the larynx

Diseases are increasingly being defined in terms of genetic alterations. A body of information termed "molecular pathogenesis" is evolving which provides a framework for integrating the rapidly accumulating genetic information with the related disease process. Molecular methods with their increased sensitivity and specificity are required to gather this information. A major challenge now lies in the transfer of this molecular technology from a research environment to the clinical testing arena. Technical issues, patented technology, special facilities, personnel, and regulatories issues imposed by CLIA'88, require those desiring to perform molecular tests to pay special attention to laboratory design, personnel training, and test menu development. Although establishing a successful molecular diagnostics laboratory is a complex and difficult task, the added value of these tests can have a tremendous impact in disease diagnosis and patient management.     

Bronchial atresia associated with epibronchial right pulmonary artery and aberrant right middle lobe artery

We report a case of bronchial atresia associated with an epibronchial right pulmonary artery (ERPA) and an aberrant right middle lobe artery (ARMLA). CT showed a branching opacity, which was hyperintense on MR images, in the anterior segment of the right upper lobe with segmental hyperinflation and the ERPA. At surgery, the ARMLA was found to originate from the ERPA, crossing the anterior aspect of the right upper lobe bronchus. It is postulated that the ARMLA might have interfered with the normal bronchial development, leading to the development of segmental bronchial atresia.     

Diagnosis of pulmonary embolism with spiral and electron-beam CT

PURPOSE: To compare spiral (SCT) and electron-beam CT (EBT) for the diagnosis of pulmonary embolism (PE). MATERIALS AND METHODS: From June 1997 to June 1998 188 patients with suspected acute or chronic thromboembolism of the pulmonary arteries were examined. A total of 108 patients were scanned using SCT and 80 patients using EBT. On each scanner two different scan protocols were evaluated. RESULTS: PE was diagnosed in 38 patients using EBT and in 49 patients using SCT. Especially with EBT, isolated peripheral emboli could be confidently diagnosed. When EBT and SCT were compared for the analysis of peripheral pulmonary arteries, some paracardiac segmental and subsegmental vessels were significantly better analyzable with EB. Additional or diseases other than PE were diagnosed in 112 patients. Other diagnoses included bronchial carcinoma and aortic dissection. CONCLUSIONS: Advanced CT scanning techniques allow the highly accurate diagnosis of central and peripheral PE. Other potentially life-threatening underlying diseases are also readily recognized.     

Image processing and spiral CT of the thorax

The data set of the thorax acquired by spiral CT is volumetric. Such data can be processed so that conventional axial sections are supplemented by reconstructed images, in an attempt to answer specific clinical questions. This review considers three reconstruction techniques: multiplanar reformation, three-dimensional rendering and sliding-thin slab reconstruction. Their relative benefits and limitations are considered, as are the implications of image processing in general.     

Detection of coronary artery calcifications predicting coronary heart disease: comparison of fluoroscopy and spiral CT

The aim of this study was to evaluate the clinical relevance of coronary artery calcifications detected by spiral CT, congruence with fluoroscopy (FS) and coronary angiography, and comparison with studies reporting on application of double-helical CT and ultrafast CT. Forty patients underwent spiral CT (2-mm slice thickness, table feed 3 mm/s), coronary angiography, and FS (performed in the usual manner). Stenosis and calcifications were evaluated semiquantitatively. Nineteen patients suffering from a stenosis >/= 75 % were verified at coronary angiography. All had coronary artery calcification on spiral CT. Fluoroscopy did not detect 8 of 19 patients with a stenosis >/= 75 % (1 vessel: n = 1; 2 vessels: n = 3; 3 vessels: n = 4). In spiral CT sensitivity was 100 % and specificity was 33 % (FS: 58 and 48 %). Positive predictive value was 83 % for spiral CT (FS: 50 %), and negative predictive value was 100 % (FS: 56 %). A significant linear increase in the calcification score was found for increasing maximal stenosis (p < 0.005). Spiral CT is more sensitive than FS in the recognition of hemodynamic relevant stenoses using the detection of coronary artery calcifications. Statistical parameters are comparable to ultrafast-CT. Spiral CT is a suitable non-invasive diagnostic technique in coronary heart disease. Coronary calcifications found incidentally in symptomatic patients at chest CT should be reported to the referring physician for further cardiological workup.     

Congenital absence and aberrant course of the internal carotid artery

OBJECTIVE: To evaluate the extent of vascularization by assessing vascular surface density in renal cell carcinomas (RCCs) of different nuclear grades, and in normal renal cortex and medulla. MATERIALS AND METHODS: Specimens of 79 RCCs of different nuclear grades (16 of G1, 42 of G2 and 21 of G3) were immunostained with the lectin Ulex europaeus agglutinin-I (UEA I). The vascular surface density of tumour tissue was assessed stereologically using a test grid at x400 magnification and compared to the values obtained in normal renal tissue. RESULTS: G3 tumours had a lower vascular surface density than had G1 and G2 RCCs and normal renal tissue of the cortex and medulla (P < 0.001, respectively). G1 tumours had a significantly higher vessel density than had normal medullary parenchyma and G2 carcinomas (P < 0.001). Vessel density was not significantly different among G1 tumours and cortical parenchyma in controls and among normal medullary tissue and G2 tumours. Statistical analysis showed that the vascular surface density was independent of tumour stage and size and the age and sex of the patients. CONCLUSION: The degree of vascularization in RCCs decreased with their grade of differentiation, suggesting that the extent of neovascularization in tumour tissue reflects the relationship between tumour cell proliferation and vascular growth. The values of vascular surface density in normal renal tissue of the cortex and medulla partially overlapped with those obtained in tumour tissue.     

Hilar cholangiocarcinoma: thin-section spiral CT findings with cholangiographic correlation

Hilar cholangiocarcinoma, a highly lethal tumor, is difficult to diagnose with conventional computed tomography (CT) because of its small size. Spiral CT allows more effective evaluation of these small lesions and better demonstrates the status of the hepatic arterial or portal venous circulation. Among 27 patients with hilar cholangiocarcinoma (infiltrative in 21, exophytic in two, polypoid in one, diffuse in three), thin-section spiral CT allowed identification of each tumor as an area of focal wall thickening that obliterated the lumen. Seventeen of the infiltrative tumors (81%) showed high attenuation. Identification of the level of biliary obstruction was possible in 63% of the patients (17 of 27). The level of obstruction was underestimated in six patients and overestimated in four. Spiral CT is a valuable method for diagnosis of hilar cholangiocarcinoma; however, spiral CT is less accurate in evaluation of intraductal tumor extent because of the limited z-axis resolution.     

Pulmonary embolism: prospective comparison of spiral CT with ventilation-perfusion scintigraphy

PURPOSE: To compare prospectively the accuracy of spiral computed tomography (CT) with that of ventilation-perfusion scintigraphy for diagnosing pulmonary embolism. MATERIALS AND METHODS: Within 48 hours of presentation, 142 patients suspected of having pulmonary embolism underwent spiral CT, scintigraphy, and (when indicated) pulmonary angiography. Pulmonary angiography was attempted if interpretations of spiral CT scans and of scintigrams were discordant or indeterminate and intermediate-probability, respectively. RESULTS: In the 139 patients who completed the study, interpretations of spiral CT scans and of scintigrams were concordant in 103 patients (29 with embolism, 74 without). In 20 patients, intermediate-probability scintigrams were interpreted (six with embolism at angiography, 14 without); diagnosis with spiral CT was correct in 16. Interpretations of spiral CT scans and those of scintigrams were discordant in 12 cases; diagnosis with spiral CT was correct in 11 cases and that with scintigraphy was correct in one. Spiral CT and scintigraphic scans of four patients with embolism did not show embolism. Sensitivities, specificities, and kappa values with spiral CT and scintigraphy were 87%, 95%, and 0.85 and 65%, 94%, and 0.61, respectively. CONCLUSION: In cases of pulmonary embolism, sensitivity of spiral CT is greater than that of scintigraphy. Interobserver agreement is better with spiral CT.     

In utero ultrasonographic diagnosis of an aberrant umbilical vein associated with fetal hepatic hyperechogenicity

Intra-hepatic abnormalities of the fetal umbilical venous system are poorly documented and clinically not well understood. A case of routine ultrasound examination at 23 weeks' gestation demonstrating foci of hepatic hyperechogenicity and cardiomegaly is presented. Colour Doppler detected absence of flow in the ductus venosus and markedly increased blood flow through an aberrant channel connecting the umbilical vein with the right atrium. The pregnancy was terminated and anomalous venous drainage of the umbilical vein into an enlarged hepatic vein was found, as well as hepatic congestion and focal hepatic necrosis and calcifications. Incidental findings of fetal hepatic hyperechogenicities require colour Doppler investigation of the intra- and extra-hepatic venous systems. We propose that a thrombo-embolic mechanism may be involved in the pathogenesis of these lesions.     

CT angiography of the carotid artery

CT angiography shows promise as a noninvasive method to display carotid vascular pathology. This article discusses technique, stenosis measurements, pitfalls, strengths, and weaknesses of CT imaging of the carotid artery.     

3-D spiral CT in diagnosis of orbital tumors with intracranial involvement

3-D-Spiral-CT was performed in 2 patients with orbita tumors with intracranic portion. 3-D-CT is enable to visualize the bony connections and judgement of bony destruction. Because of methodical parameters 2D-CT must be the basic of clinical diagnostic.