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Adel Maataoui

Publications and source records attributed to Adel Maataoui.

13 recordsLinked to original sources
PubMed2006

Facilitating coronary artery evaluation in MDCT using a 3D automatic vessel segmentation tool.

The purpose of this study was to investigate a 3D coronary artery segmentation algorithm using 16-row MDCT data sets. Fifty patients underwent cardiac CT (Sensation 16, Siemens) and coronary angiography. Automatic and manual detection of coronary artery stenosis was performed. A 3D coronary artery segmentation algorithm (Fraunhofer Institute for Computer Graphics, Darmstadt) was used for automatic evaluation. All significant stenoses (>50%) in vessels >1.5 mm in diameter were protocoled. Each detection tool was used by one reader who was blinded to the results of the other detection method and the results of coronary angiography. Sensitivity and specificity were determined for automatic and manual detection as well as was the time for both CT-based evaluation methods. The overall sensitivity and specificity of the automatic and manual approach were 93.1 vs. 95.83% and 86.1 vs. 81.9%. The time required for automatic evaluation was significantly shorter than with the manual approach, i.e., 246.04+/-43.17 s for the automatic approach and 526.88+/-45.71 s for the manual approach (P<0.0001). In 94% of the coronary artery branches, automatic detection required less time than the manual approach. Automatic coronary vessel evaluation is feasible. It reduces the time required for cardiac CT evaluation with similar sensitivity and specificity as well as facilitates the evaluation of MDCT coronary angiography in a standardized fashion.

Aged↗
PubMed2006

Navigation-based needle puncture of a cadaver using a hybrid tracking navigational system.

PURPOSE: The purpose of this study was to determine the puncture accuracy of a navigational system, Medarpa, in a soft tissue environment using augmented overlay imaging. MATERIALS AND METHODS: Medarpa is an optical electromagnetic tracking system, which allows tracking of instruments, the radiologist's head position, and the transparent display. The display superimposes a computed tomography scan of a cadaver chest on a human cadaver in real time. In group A, needle puncture was performed using the Medarpa system. Three targets located inside the cadaver chest were selected. In group B, the same targets were used to perform standard computed tomography-guided puncture using a single-slice technique. A total of 42 punctures were performed in each group. Postpuncture computed tomography scans were made to verify needle tip positions. RESULTS: Mean deviation from targets was 8.42 mm +/- 1.78 mm for group A and 8.90 mm +/- 1.71 mm for group B. No significant difference was found between group A and B in any target (P > 0.05). No significant difference was found between the targets of the same group (P > 0.05). Procedural time for 42 punctures was 160 minutes in group A versus 289 minutes in group B (P < 0.05). CONCLUSION: Needle puncture in a soft tissue environment using the navigational system Medarpa can be reliably performed and matches the accuracy achieved by a computed tomography-guided puncture technique.

Biopsy, Needle↗
PubMed2005

Quantitative cartilage volume measurement using MRI: comparison of different evaluation techniques.

This study was aimed to investigate the accuracy and time saving of MRI Argus application in the assessment of cartilage volume in osteoarthritic knees. Twelve knees of patients suffering from osteoarthritis were scanned with a 1.5 T MRI using a 3D gradient echo sequence with selective water excitation. Cartilage volume of the tibial and patellar compartment was determined with a validated multiprocessing computer system (Octane Duo, Silicon Graphics, Mountain View, Calif., USA). The calculated cartilage volumes were compared to the results acquired by the Argus (Siemens Inc., Erlangen, Germany) application software using the MRI data sets. Compared to the multiprocessing computer system a time saving of at least 30 min for cartilage volume determination was achieved. The mean differences of Argus versus the multiprocessing computer system were 4.26+/-0.84 and 7.80+/-0.87% for the medial and lateral tibial plateau and 5.94+/-0.59% for the patella (no statistical significant difference; P>0.05). The applied Argus software can be used for fast and accurate determination of cartilage volume in the knee joint.

Aged↗
PubMed2005

Multislice CT of the pelvis: dose reduction with regard to image quality using 16-row CT.

To optimize examination protocols of 16-row multi-detector CT (MDCT) of pelvis for dose reduction with regard to image quality. MDCT of pelvis was performed on 12 cadaver specimens with stepwise reduction of tube current from 160 mA (113, 80, 56, 40, 28) to 20 mA at 120 kV. Scan parameters were 16 x 1.5 mm collimation. Reconstructions of axial and coronal images were used for evaluation of cortex, trabeculum, image quality, image noise, acetabulum and iliosacral (ISJ) joints. After data were blinded, evaluation of images was done by three radiologists according to 5-point Likert scale. Accuracy of the observers in sorting films according to dose reduction was determined with kappa coefficient. Mean values of image evaluation were determined. Pronounced deterioration of image quality for all criteria was observed between 80 and 28 mA. Adequate image quality was obtained at 40 mA [effective dose (E): 2.2 mSv, CTDI(w): 2.8 mGy] for criterion detailed definition of acetabulum and ISJ and at 80 mA (E: 4.4 mSv, CTDI(w): 5.6 mGy) for remaining criteria. Moderate agreement was observed between the three observers (kappa coefficient: 0.31). All observers were excellent in arranging images according to decreasing dose. Using 16-row MDCT image quality of pelvis is acceptable at 80 mA and 120 kV. This translates into a dose reduction of 33% of average value of the nationwide survey of the German Roentgen Society (1999) for this type of examination.

Acetabulum↗
PubMed2005

Accuracy of biopsy needle navigation using the Medarpa system--computed tomography reality superimposed on the site of intervention.

The aim of this work was to determine the accuracy of a new navigational system, Medarpa, with a transparent display superimposing computed tomography (CT) reality on the site of intervention. Medarpa uses an optical and an electromagnetic tracking system which allows tracking of instruments, the radiologist and the transparent display. The display superimposes a CT view of a phantom chest on a phantom chest model, in real time. In group A, needle positioning was performed using the Medarpa system. Three targets (diameter 1.5 mm) located inside the phantom were punctured. In group B, the same targets were used to perform standard CT-guided puncturing using the single-slice technique. The same needles were used in both groups (15 G, 15 cm). A total of 42 punctures were performed in each group. Post puncture, CT scans were made to verify needle tip positions. The mean deviation from the needle tip to the targets was 6.65+/-1.61 mm for group A (range 3.54-9.51 mm) and 7.05+/-1.33 mm for group B (range 4.10-9.45 mm). No significant difference was found between group A and group B for any target (p>0.05). No significant difference was found between the targets of the same group (p>0.05). The accuracy in needle puncturing using the augmented reality system, Medarpa, matches the accuracy achieved by CT-guided puncturing technique.

Biopsy, Needle↗
PubMed2005

Liver metastases in rats: chemoembolization combined with interstitial laser ablation for treatment.

PURPOSE: To assess the effect of transcatheter arterial chemoembolization (TACE) combined with laser-induced thermotherapy (LITT) for treatment of liver metastases in an animal model. MATERIALS AND METHODS: All experiments were approved by the German government and the institutional animal research review board. After subcapsular liver implantation of colorectal cancer cells in 30 WAG rats (on day 0), the animals were randomly assigned to three interventional treatment groups. In the 10 rats in group A, TACE was performed: Fourteen days after cancer cell implantation and within 20 minutes after laparotomy and retrograde placement of a microcatheter into the gastroduodenal artery, these rats were injected with mitomycin (0.1 mg), iodized oil (0.1 mL), and degradable starch microspheres (5.0 mg). In the 10 rats in group B, LITT was performed: Also on day 14, the tumors in these animals were exposed to Nd:YAG laser light of 1064 nm at 2 W for 5 minutes. In the 10 rats in group C, combined treatment was administered: TACE was performed on day 14, and LITT was performed on day 21. Tumor volumes were measured before (on day 13) and after (on day 28) treatment with magnetic resonance (MR) imaging, and the mean tumor growth ratio (day 13 tumor volume divided by day 28 tumor volume) was calculated. RESULTS: The mean tumor volumes measured before and after the treatments were, respectively, 0.11 and 0.60 cm(3) in group A, 0.11 and 0.68 cm(3) in group B, and 0.11 and 0.35 cm(3) in group C. The mean tumor growth ratio was 5.42 in group A, 6.14 in group B, and 3.15 in group C. According to Bonferroni test results, compared with the rats in groups A and B (controls), the group C rats had significantly inhibited tumor growth (P < .01 for both comparisons). CONCLUSION: Use of combined TACE-LITT treatment, compared with the use of TACE or LITT alone, significantly inhibits tumor growth.

Analysis of Variance↗
PubMed2004

MDCT of the proximal anastomoses created by nitinol implants in coronary artery bypass grafting: a retrospective two-observer evaluation.

The purpose of this study was to investigate the proximal anastomosis of CABG grafts created by a nitinol aortic connector. After receiving CABG, 33 patients underwent CT examination of the heart. On the same patients, CT was performed on postoperative day 5 (4-row CT, group A) and again 1 year thereafter (16-row CT, group B). Twenty-three ACVB to RCX and 27 ACVB to RCA grafts were included. Every anastomosis was reviewed under different reformations (MIP, MPR and VRT). Interobserver correlation was determined. Five days postoperatively, 48/50 anastomoses were classified as patent. One year postoperatively, 42/50 anastomoses were classified as patent. In both groups, the aortic connector could be visualized with good quality: 1.82+/-1.10 (group A) and 1.93+/-1.22 (group B) for ACVB to RCA, similar results for ACVB to RCX grafts (MPR). Image quality at the aortic connector site did not display a significant difference for any reformation between groups (P>0.05). Within groups, MPR displayed better visualization than MIP and VRT (P<0.05). In the presence of metal implants, CT provides reliable data in evaluation of the proximal anastomosis. Sixteen-row CT does not bring a significant benefit to image quality. MPR displayed the best visualization within both groups.

Aged↗
PubMed2004

Visualisation of non-invasive coronary bypass imaging: 4-row vs. 16-row multidetector computed tomography.

UNLABELLED: The purpose of this study was to investigate the image quality of coronary artery bypass graft visualization in 4- and 16-row multidetector CT using multiple imaging reformations. MATERIAL AND METHODS: One hundred sixteen patients underwent CT examination of the heart after receiving CABG. Group A (n=58) received 4-row MDCT; group B (n=58) received 16-row MDCT. Various bypass types such as LITA to LAD and venous grafts to the RCA and RCX were included in the study. A five-point Likert scale was used to grade image quality. Each bypass was reviewed under different imaging reformations: thin slap maximum intensity projection (MIP thin), multiplanar reformation (MPR) and volume rendering technique (VRT). Special attention was paid to the delineation of the distal anastomosis. Interobserver correlation was determined. RESULTS: From 289 bypass grafts examined, 279 (96.54%) were classified as patent and 10 (3.46%) as not patent. Except for the distal anastomosis, 16-row MDCT showed significantly better results for all segments of bypasses. Comparison of reformations within group A and B showed that MIP thin (P<0.05) and VRT (P<0.05) displayed better visualization as compared to MPR. CONCLUSION: Significantly better imaging of all bypass types is possible using 16-row MDCT as compared to 4-row MDCT. Assessment of the distal anastomosis yields no difference between 4- and 16-row technology.

Adult↗
PubMed2004

Virtual endoscopy of the tracheo-bronchial system: sub-millimeter collimation with the 16-row multidetector scanner.

The purpose of this study was to evaluate the scope of sub-millimeter collimation reconstruction parameters using 16-row computer tomography and ECG triggering on image quality in virtual bronchoscopy. Thirty-two patients (5 women, 27 men, mean age 66.6+/-1.4) who had been admitted for coronary artery bypass graft surgery underwent CT examination of the thorax (Sensation 16, Siemens, Inc., Forchheim, Germany). All patients were examined with 16x0.75-mm collimation. Image reconstruction was performed for two groups. In group A ( n=32), slice thickness of 1.5 mm and an overlap of 0.75 mm were used. In group B ( n=32), slice thickness of 0.75 mm and an overlap of 0.4 mm were applied. Retrospective ECG triggering was performed in all patients. The maximum order of recognizable bronchi was determined in each data set. In addition to assessing the maximum order of bronchial bifurcation, bronchial diameter was determined in truly perpendicular sections in each patient. For every segment proximal to a bifurcation, image quality was subjectively graded as poor (grade 1), moderate (grade 2) or good (grade 3). The observers were asked to identify the minimum cardiac movement ECG-triggered image sets assuming that they would be of better quality than the maximum cardiac movement ECG-triggered image sets. The Mann-Whitney U-test and the Fisher's Exact Test were used for statistical evaluation. In group A, a mean of 4.8+/-0.2 bifurcations was ascertained vs. 6.5+/-0.3 bifurcations in group B [ P<0.0003]. For bronchial diameters in group A, a mean of 7.5+/-0.4 mm was determined vs. 4.6+/-0.4 mm in group B [ P<0.0001]. In group B, two independent radiologists observed a significant shift to better image quality in all segments evaluated [ P<0.006 to P<0.000001]. Motion artifacts were judged as being significantly reduced by minimum cardiac movement ECG-triggering in group B [observer 1: P=0.0007 (20/32); observer 2: P=0.008 (18/32)], but not in group A [observer 1: P=0.286 (13/32); observer 2: P=0.123 (16/32)]. Sub-millimeter collimation and minimum cardiac movement ECG-triggered data acquisition allow deeper penetration into the tracheo-bronchial system allowing visualization of the bronchial surface down to diameters below 5 mm in certain cases up to the eighth bifurcation. Along with an enhanced visualization as such, better image quality is acquired in all segments evaluated. Trade off between better image quality, of doubtful diagnostic consequence, and much higher irradiation dose must be made.

Aged↗
PubMed2003

Hyperthermic preconditioning protects pig islet grafts from early inflammation but enhances rejection in immunocompetent mice.

The induction of heat shock proteins (HSP) protects isolated islet cells against the cytotoxicity of inflammatory mediators in vitro. Very little information is available about the effect of HSP overexpression on function of preconditioned islet grafts. The present study investigated the function of heat-exposed pig islets after transplantation into immunocompetent mice in comparison with in vitro resistance against inflammatory mediators. Pig islets were preconditioned at 43 degrees C or sham treated prior to subcapsular transplantation into diabetic C57/Bl6j mice. Nondiabetic mice simultaneously receiving preconditioned and control islets were subjected to bilateral nephrectomy for determination of pig insulin. Resistance against H2O2, NO, human Il-1beta, IFN-gamma, or TNF-alpha was assessed by trypan blue exclusion and insulin determination. Heat-induced protein expression was confirmed by Western blot analysis. Graft preconditioning increased resistance against H2O2, NO, or cytokines (p < 0.05) but decreased survival in nondiabetic mice (p < 0.05) and function in diabetic mice (p < 0.01). Upregulation of caspase-3 activity as well as Bax, Fas, FasL, and DFF expression (p < 0.05) indicated simultaneous induction of apoptosis. The coexpression of HSP and proapoptotic proteins reveals the dual character of the stress response simultaneously starting mechanisms for protection and apoptosis. In vitro assays seem to reflect only insufficiently the situation of islets after transplantation.

Animals↗