Multislice Computed Tomography Data Research Articles

Evaluation of a semiautomatic software tool for left ventricular function analysis with 16-slice computed tomography

The purpose of the study was to evaluate a semiautomatic analysis tool for assessing global left ventricular myocardial function with multislice computed tomography (MSCT). We examined 33 patients with MSCT using 16x0.5 mm detector collimation and magnetic resonance imaging (MRI) on a 1.5-T scanner. MSCT data were analyzed using semiautomatic volumetric analysis software (ANET, CSCF-001A, Toshiba). This software tool automatically creates endo- and epicardial contours that can be manually corrected on all short-axis slices at all reconstructed time points within the cardiac cycle, based on a contour-detection and density-threshold algorithm. All global left ventricular function parameters assessed with the semiautomatic MSCT software were highly correlated with the results of MRI. Bland-Altman analysis showed minor systematic overestimation of end-diastolic (10.7 ml) and end-systolic volumes (5.6 ml) and underestimation of ejection fraction (2.1%) with MSCT as compared with MRI. The post-processing time was moderately but significantly longer with the MSCT software (15.9+/-2.8 min) than necessary for MRI (14.0+/-2.5 min, P<0.01), mainly as a result of the longer time required for uploading of the MSCT datasets, which were on average 54 times larger (1.3 GByte). In conclusion, it appears feasible to accurately assess global left ventricular function with MSCT in a reasonable post-processing time using a semiautomatic software tool.

Bestimmung linksventrikulärer Funktionsparameter: Vergleich von 16-Zeilen-Mehrschicht-CT mit der MR-Tomographie

The quantitative measurement of left ventricular functional parameters using multislice computed tomography (MSCT) with retrospective ECG-gating and comparison of the results with magnetic resonance imaging (MRI). Thirty-one patients with suspected or known coronary artery disease underwent MSCT angiography with retrospective ECG-gating (Sensation 16, Siemens). Based on the CT data set, short axis reformations of the left ventricle were performed for functional analysis. On a commercially available workstation, end-diastolic- (EDV), end-systolic- (ESV), stroke volume (SV), ejection fraction (EF) and myocardial mass (MM) were calculated from MSCT (temporal resolution 105 - 210 ms) data according to the modified Simpson's rule and compared to MRI (1.5 T scanner, temporal resolution 48 ms) using a 2D TrueFISP cine sequence with respiration hold. In all cases, the quality was adequate for both MSCT and MRI. MSCT and MRI had an excellent correlation for EDV (r = 0.86), ESV (r = 0.91), EF (r = 0.87) and MM (r = 0.88), and a good correlation for SV (r = 0.70). The mean difference was 13.2 +/- 21.9 ml for EDV, 8.7 +/- 15.9 ml for ESV, 4.6 +/- 12.3 ml for SV, 1.4 +/- 5.2 % for EF, and 11.9 +/- 13.8 g for MM. However, EDV (p = 0.002), ESV (p = 0.005), SV (p = 0.048), and MM (p < 0.0001) were significantly overestimated with MSCT compared to MRI. For EF, no significant difference between MSCT and MRI was found (p = 0.15). For left ventricular functional parameters, MSCT of the heart with retrospective ECG-gating showed a high correlation with MRI, which has an important implication when using MSCT for non-invasive cardiac imaging. Despite the high correlation, overestimation of EDV, EVS, SV, and MM with MSCT has to be taken into account when applying this technology in clinical practice. EF was not significantly different between both modalities.

Evaluation of Venous and Arterial Conduit Patency by 16-Slice Spiral Computed Tomography

Computed tomography has been shown to be useful in the evaluation of aortocoronary bypass grafts (CABG). This is the first prospective study to evaluate the accuracy of a new-generation scanner in the detection of patency and significant stenoses (>50% decrease in diameter) of venous and arterial grafts in patients with previous CABG. In 96 patients (80 males, mean age 62 years) with previous CABG, a multislice computed tomography (MSCT) scan was performed (collimation 16x0.625 mm). Patients with atrial fibrillation, renal failure, severe respiratory disease, severe heart failure, heart rate >70 bpm despite therapy, or unstable angina were excluded. A total of 285 conduits implanted on the native coronary arteries at the time of CABG were evaluated. MSCT data were analyzed by 2 independent radiologists and compared with the results of conventional angiography. Three patients were excluded from analysis. All conduits were judged evaluable in 84 patients. Among these patients, MSCT correctly diagnosed 54 occluded grafts and 4 significant stenoses on the body of the grafts. Of the 17 significant anastomotic lesions, MSCT correctly diagnosed 15. For these 84 patients, diagnostic accuracy was 99%, sensitivity was 97%, and specificity was 100%. When all 93 patients were considered, the sensitivity of MSCT in diagnosing significant stenoses was 96%. MSCT with the new-generation scanner allows for accurate assessment of venous and arterial conduits in patients with previous CABG with a high degree of sensitivity and specificity. Exclusion criteria and radiation exposure remain limitations of the method.

Visualization and Quantification of Air Embolism Structure by Processing Postmortem MSCT Data

Venous air embolism (VAE) is an often occurring forensic finding in cases of injury to the head and neck. Whenever found, it has to be appraised in its relation to the cause of death. While visualization and quantification is difficult at traditional autopsy, Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) offer a new potential in the diagnosis of VAE. This paper reports the findings of VAE in four cases of massive head injury examined postmortem by Multislice Computed Tomography (MSCT) prior to autopsy. MSCT data of the thorax were processed using 3D air structure reconstruction software to visualize air embolism within the vascular system. Quantification of VAE was done by multiplying air containing areas on axial 2D images by their reconstruction intervals and then by summarizing the air volumes. Excellent 3D visualization of the air within the vascular system was obtained in all cases, and the intravascular gas volume was quantified.

Sixteen-row multislice computed tomography in the assessment of pulmonary veins prior to ablative treatment: validation vs conventional pulmonary venography and study of reproducibility.

The aim of this study was to validate multislice computed tomography (MSCT) venography measurements of pulmonary vein (PV) diameters vs conventional pulmonary venography (CPV), and to assess the reproducibility of MSCT data. The study included 21 consecutive patients with atrial fibrillation who were planned for cryothermal ablation of PVs. One day before ablation, all patients underwent CPV and contrast-enhanced non-gated MSCT venography. The MSCT was repeated 3 months after ablation. The CPV images of the treated PVs ( n=40) were analyzed and compared with the results of MSCT measurements. Reproducibility of MSCT venography-based data was assessed by interobserver ( n=84 PVs) and interexamination ( n=44 PVs) variability. Pre-treatment PV diameters on MSCT and CPV showed good correlation ( r=0.87, p<0.01; 18.9+/-.2.3 mm, 188.5+/-.2.4 mm, respectively). Interobserver agreement and interexamination reproducibility were good ( r=0.91, r=0.82, respectively, p<0.01), with narrow limits of agreement (Bland and Altman method). The MSCT venography allows accurate and reproducible assessment of PVs. It can be used both in non-invasive planning of treatment for ablative therapy and in the follow-up of patients.

General surface reconstruction for cone-beam multislice spiral computed tomography.

A new family of cone-beam reconstruction algorithm, the General Surface Reconstruction (GSR), is proposed and formulated in this paper for multislice spiral computed tomography (CT) reconstructions. It provides a general framework to allow the reconstruction of planar or nonplanar surfaces on a set of rebinned short-scan parallel beam projection data. An iterative surface formation method is proposed as an example to show the possibility to form nonplanar reconstruction surfaces to minimize the adverse effect between the collected cone-beam projection data and the reconstruction surfaces. The improvement in accuracy of the nonplanar surfaces over planar surfaces in the two-dimensional approximate cone-beam reconstructions is mathematically proved and demonstrated using numerical simulations. The proposed GSR algorithm is evaluated by the computer simulation of cone-beam spiral scanning geometry and various mathematical phantoms. The results demonstrate that the GSR algorithm generates much better image quality compared to conventional multislice reconstruction algorithms. For a table speed up to 100 mm per rotation, GSR demonstrates good image quality for both the low-contrast ball phantom and thorax phantom. All other performance parameters are comparable to the single-slice 180 degrees LI (linear interpolation) algorithm, which is considered the "gold standard." GSR also achieves high computing efficiency and good temporal resolution, making it an attractive alternative for the reconstruction of next generation multislice spiral CT data.

Virtual endoscopy of the tympanic cavity based on high-resolution multislice computed tomographic data.

This study was designed to assess the value of high-resolution multislice computed tomography (MSCT) data of the petrous bone for the virtual endoscopic visualization of the tympanic cavity. The recently introduced MSCT technology has improved spatial resolution in the z axis as well as scan speed in computed tomography. Three-dimensional rendering of high-resolution MSCT data of the petrous bone may be expected to provide endoluminal views of superior image quality, thus competing with transtympanic endoscopy (otoendoscopy). This study was conducted at a university teaching hospital. Cadaveric phantom studies in a MSCT scanner were performed to define a data acquisition protocol, combining adequate detail resolution with low tube current. Subsequently, the cadaveric phantom underwent otoendoscopy. The postprocessing parameters of the three-dimensional rendering protocol were chosen to produce views closely resembling the corresponding otoendoscopic images. High-resolution data from 18 patients with pathologic conditions of the middle ear, as suggested by clinical findings and assessment of cross-sectional data, were postprocessed using the volume rendering technique to generate standardized virtual endoscopic views. A total of 36 virtual endoscopic scans of the tympanic cavity were generated. With regard to intermediate and high-density structures, virtual endoscopic images, based on MSCT data, yielded endoluminal views closely resembling corresponding otoendoscopic views. Virtual endoscopy seems useful for imaging ossicular pathologic conditions such as dysplasia and chain disruption as well as for assessing patient status before and after otosurgery. MSCT data sets allow for generating virtual endoscopic views closely resembling otoendoscopic images. The technique is especially useful when ossicular pathologic changes are present as well as for preoperative and postoperative imaging of otologic procedures.