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Manuel Belgrano

Publications and source records attributed to Manuel Belgrano.

10 recordsLinked to original sources
PubMed2005

Diagnostic accuracy of multislice computed tomography coronary angiography is improved at low heart rates.

PURPOSE: Assess the effect of heart rate on diagnostic accuracy for the detection of significant coronary artery stenosis using 16-row multislice computed tomography (MSCT). MATERIAL AND METHODS: About 120 patients (105 males; 59+/-11 years) with suspected coronary artery disease who underwent conventional coronary angiography (CA) and MSCT-CA were retrospectively enrolled for the study. Patients underwent a MSCT-CA (Sensation 16, Siemens, Germany), with the following protocol: collimation 16 x 0.75 mm, gantry rotation time 420 ms, feed/rotation 3.0 mm, kV 120, mAs 400-500. The protocol for contrast material administration was 100 ml of Iodixanol (Visipaque 320 mg l/ml, Amersham, UK) at 4 ml/s and the delay was defined with a bolus tracking technique. In all patients the mean heart rate (HR) during the scan was used as a criteria to divide the population in two groups of 60 patients each. In one group (Low HR) the 60 patients with lower heart rates, and in the other group (High HR) the patients with higher heart rates. In the two groups diagnostic accuracy (per coronary segment) for the detection of significant stenosis (>or=50% lumen reduction) was evaluated in vessels >or=2 mm of diameter using quantitative CA as reference standard. The difference in diagnostic accuracy were compared with a Chi(2) test and a p<0.05 was considered significant. RESULTS: There was no significant difference between the two groups regarding age, gender, weight, mean intravascular attenuation, and calcium score. Overall 1,310 (652 for Low HR and 658 for High HR) segments with 219 (105 for Low HR and 114 for High HR) significant lesions were available for the analysis. The average heart rate was 52+/-4 HU and 63+/-5 HU for Low HR and High HR, respectively (p<0.001). The sensitivity and specificity were 92 and 96% for Low HR and 90 and 92% for High HR (p<0.05). There were 22 vs. 44 false positives, and 8 vs. 12 false negatives in the Low HR and High HR, respectively. CONCLUSION: Increasing HR significantly deteriorates diagnostic accuracy in MSCT-CA.

Chi-Square Distribution↗
PubMed2005

3D reconstruction techniques made easy: know-how and pictures.

Three-dimensional reconstructions represent a visual-based tool for illustrating the basis of three-dimensional post-processing such as interpolation, ray-casting, segmentation, percentage classification, gradient calculation, shading and illumination. The knowledge of the optimal scanning and reconstruction parameters facilitates the use of three-dimensional reconstruction techniques in clinical practise. The aim of this article is to explain the principles of multidimensional image processing in a pictorial way and the advantages and limitations of the different possibilities of 3D visualisation.

Audiovisual Aids↗
PubMed2005

Image assessment with multislice CT coronary angiography.

AIM: To investigate the diagnostic accuracy of two different protocols for image evaluation used in multislice computed tomography coronary angiography (MSCT-CA). MATERIALS AND METHODS: Sixty patients with suspected coronary artery disease undergoing conventional coronary angiography (CA) were enrolled for MSCT-CA. All patients underwent 16-row MSCT (Sensation 16, Siemens, Germany) with the following parameters: detector rows 16, collimation 0.75 mm, gantry rotation time 375 ms. Two independent observers assessed the images for significant stenosis using a a protocol with standard projections and a three-dimensional protocol. The diagnostic accuracy for both methods was calculated using quantitative CA as a reference standard. RESULTS: The sensitivity, specificity, negative predictive value and positive predictive value obtained with the conventional projection protocol and with three-dimensional protocol were: 54% and 93%, 97% and 97%, 76% and 86%, 92% and 99%, respectively. CONCLUSIONS: Conventional projections in the assessment of MSCT-CA provide insufficient diagnostic accuracy compared with three-dimensional processing.

Contrast Media↗
PubMed2005

Influence of increasing convolution kernel filtering on plaque imaging with multislice CT using an ex-vivo model of coronary angiography.

PURPOSE: To assess the variability in attenuation of coronary plaques with multislice CT-angiography (MSCT-CA) in an ex-vivo model with varying convolution kernels. MATERIALS AND METHODS: MSCT-CA (Sensation 16, Siemens) was performed in three ex-vivo left coronary arteries after instillation of contrast material solution (Iomeprol 400 mgI/ml, dilution: 1/80). The specimens were placed in oil to simulate epicardial fat. Scan parameters: slices 16/0.75 mm, rotation time 375 ms, feed/rotation 3.0 mm, mAs 500, slice thickness 1 mm, and FOV 50 mm. Datasets were reconstructed using 4 different kernels (B30f-smooth, B36f-medium smooth, B46f-medium, and B60f-sharp). Each scan was scored for the presence of plaques. Once a plaque was detected, the operator performed attenuation measurements (HU) in coronary lumen, oil, calcified and soft plaque tissue using the same settings in all datasets. The results were compared with T-test and correlated with Pearson's test. RESULTS: Overall, 464 measurements were performed. Significant differences (p<0.05) were found for the mean attenuation of lumen (B30f/B36f, B30f/B60f, B36f/B46f, B36f/B60f, and B46f/B60f), oil (B30f/B36f, B30f/B46f, B30f/B60f, B36f/B46f, and B46f/B60f), calcium (all kernels), and plaque (B30f/B36f, B30f/B46f, B30f/B60f, and B46f/B60f) using 4 different kernels. The attenuation values (mean+/-SD) within the lumen (246+/-6, 215+/-13, 248+/-5, and 270+/-7), oil (-123+/-3, -127+/-1, -121+/-6, and -127+/-4), calcified plaque tissue (703+/-334, 739+/-364, 817+/-381, and 1181+/-503), and soft plaque tissue (134+/-56, 111+/-49, 120+/-56, and 102+/-41) showed high correlation (p<0.001) when attenuation of all structures were compared in different kernels. CONCLUSIONS: Use of sharper convolution kernels significantly increases the attenuation of the calcium within coronary plaques and reduces the attenuation of soft plaque tissue.

Aged↗
PubMed2005

Direct contrast enhanced MR in the study of central venous accesses in children receiving total parenteral nutrition.

PURPOSE: To present direct contrast-enhanced Magnetic Resonance Venography, a recently developed method for the study of central venous accesses. MATERIALS AND METHODS: Six patients (4 males and 2 females; age range 15-18 years) with severe intestinal failure treated with indwelling central venous catheter since childhood were studied by MR-angiography. The examination was carried out with a 1.5 Philips Gyroscan Intera magnet, sequences during the simultaneous injection of about 60 ml/limb paramagnetic contrast material, Gd-DTPA, diluted with saline solution at a ratio of 1:12. The images were processed with maximum intensity coronal projections and compared with the phlebographic images obtained earlier. RESULTS: In 4 cases the method demonstrated superior vena cava occlusion, in 2 cases inferior vena cava occlusion. The examination was well tolerated by all patients and image quality was very similar to that of the gold-standard study, conventional phlebography. CONCLUSIONS: We believe direct contrast-enhanced MR-venography to be a minimally invasive, panoramic and diagnostically reliable method, which should be considered the first choice in the study of central venous accesses of patients receiving total parenteral nutrition for the medical treatment of intestinal failure. The method does not expose the patients to ionizing radiation or require iodinated contrast material, and is relatively short with a room time of about 30-40 minutes.

Adolescent↗
PubMed2003

Endovascular treatment of external iliac artery injuries after hip arthroplasty.

PURPOSE: To report endovascular repair of injuries to the external iliac artery during hip surgery. CASE REPORTS: Two elderly women with histories of chronically infected hip prostheses were found to have iatrogenic leaking pseudoaneurysms of the external iliac artery due to hip surgery trauma in the past. Both were treated successfully with a Jostent Peripheral Stent-Graft. The first patient died 17 months after treatment, and the second was well, with an excluded false aneurysm, at the 6-month follow-up. CONCLUSIONS: Stent-graft repair may be an appropriate and effective treatment for some traumatic arterial lesions.

Aged↗
PubMedDate not supplied

Virtual stenting of iliac arteries: a new technique for choosing stents and stent-grafts by means of 3D rotational angiography. Preliminary data.

PURPOSE: Virtual stenting (VS) is a new tool in the 3D processing work station of rotational angiography (RA) systems. This tool enables the 3D visualization of a stent or stent-graft in the site of a stenotic, obstructive or aneurysmatic lesion to be treated. We report the preliminary results obtained with this software in the treatment of segmental stenotic, obstructive or aneurysmal lesions of the iliac artery. MATERIALS AND METHODS: Seventeen patients under-went rotational angiography and 3D reformations for one or more stenoses (19 cases), obstructive lesions (2 cases) or aneurysms (2 cases) of the common and/or external iliac artery and were treated with stents in 22/23 of cases. In all cases, the VS tool was applied to the stenotic-obstructive lesion on the identified on the 3D angiogram obtained before the stenting procedure. RESULTS: The measurements of the stents/stents-grafts (length, proximal and distal diameter) provided by the tool were compared to those of the stent deployed. In 22/23 procedures, the measurements of virtual stenting and those of the deployed stent showed a good level of concordance. The system failed to provide correct measurements in only one long and tortuous iliac aneurysm. CONCLUSIONS: The ''virtual stenting'' tool proved to be reliable and fast, and enabled a more objective selection of the stent to be deployed on a stenotic-obstructive lesion in almost all cases. In cases of aneurysms of marked tortuosity, the system tends to suggest an inappropriate stent. The possibility of manually defining the optimal stent path within the aneurysmal sac might be useful.

Aged↗
PubMedDate not supplied

Introduction to coronary imaging with 64-slice computed tomography.

The aim of this article is to illustrate the main technical improvements in the last generation of 64-row CT scanners and the possible applications in coronary angiography. In particular, we describe the new physical components (X-ray tube-detectors system) and the general scan and reconstruction parameters. We then define the scan protocols for coronary angiography with the new generation of 64-row CT scanners to enable radiologists to perform a CT study on the basis of the diagnostic possibilities.

Algorithms↗
PubMedDate not supplied

Impact of intravascular enhancement, heart rate, and calcium score on diagnostic accuracy in multislice computed tomography coronary angiography.

PURPOSE: To assess the effect of intravascular enhancement, heart rate, and calcium score on diagnostic accuracy in the detection of significant coronary artery stenosis using 16-row multislice computed tomography (MSCT). MATERIALS AND METHODS: One hundred patients (88 males; 59+/-11 years) with suspected coronary artery disease who had undergone conventional coronary angiography (CA) and MSCT-CA were retrospectively enrolled for the study. Patients underwent a MSCT-CA, with the following protocol: collimation 16x0.75 mm, gantry rotation time 420 ms, feed/rotation 2.8 mm, kV 120, mAs 400-500. The protocol for contrast material administration was 100 ml of Iodixanol 320 mgI/ml at 4 ml/s and the scan delay was defined with a bolus tracking technique. In all patients vascular enhancement was measured in the aortic root, and in the left and right coronary arteries. The average vascular enhancement was used to divide the population in two groups of 50 patients each, one with lower enhancement (Low), and one with higher enhancement (High). In the two groups diagnostic accuracy (per coronary segment) for the detection of significant stenosis (= or >50% lumen reduction) was evaluated in vessels = or >2 mm in diameter using quantitative CA as the reference standard. The differences in diagnostic accuracy were compared with a Chi-square test and a p<0.05 was considered significant. RESULTS: Of the total 1116 segments (= or >2 mm lumen diameter), 173 presented significant stenosis. The sensitivity and specificity for the assessment of significant stenosis were 89.4% and 93.3% vs 94.3% and 97.4% in the presence of increasing intravascular enhancement, 92.8% and 96.7% vs 91.1% and 93.9% in the presence of increasing heart rate, and 89.7% and 97.6% vs 93.3% and 92,8% in the presence of an increasing calcium score. CONCLUSIONS: Increasing intravascular enhancement significantly improves diagnostic accuracy in MSCT-CA. A higher heart rate lowers the specificity in the detection of significant obstructing lesions of the coronary artery. An increasing calcium score determines a lower specificity and a higher sensitivity.

Aged↗