Cardiac and vascular MDCT: thoracic imaging.
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Aorta, Thoracic↗
Biomedical subjects
Martin Heuschmid
Publications and source records attributed to Martin Heuschmid.
Comparison of volume-rendered and surface-rendered MR colonography.
In the United States and Europe, colorectal cancer is the second leading cause of cancer-related deaths. It is well known that colorectal carcinomas may originate from preexisting adenomas. For the visualization of colorectal cancer and other pathologic changes such as polyps, two 3D methods (volume-rendering (VR) and surface-rendering (SR)) in MR colonography were compared in our study. MR colonography was carried out in 17 patients on a 1.5 T MR scanner using a 10 mmolar gadolinium water solution enema. Coronal as well as rotated VR and SR views were compared in order to examine the technical quality (TQ) of the visualization model and grade of confidence (GC) in the pathological findings. Colonoscopic findings revealed 8 colorectal carcinoma, 10 patients with polyps, 4 diverticular disease, and 2 with redundant bowel loops. Based on a total of 248 colonic segments for both visualization methods, volume rendering were significantly superior to surface rendering for both, TQ (p<0.0001) and GC (p<0.0001). Volume rendering and surface rendering were not dependent on individual colon segments (p=0.13 for TQ and p=0.18 for GC) or on image rotation (p=0.06 for TQ and p=0.062 for GC). It is also independent of the type of pathology (p=0.31 for TQ and p=0.42 for GC) and the reviewers (p=0.62 for TQ and p=0.88 for GC). This indicates, that for the purpose of interpreting the technical quality and pathological findings, volume rendering is superior to surface rendering in MR colonography. Volume rendering could be used as an 3D visualization tool, enabling MR colonography examinations to be completed sooner in cases where colon distension is sufficient, and it would also provide an overview of potential mass lesions.
Aged↗
Virtual bronchoscopy: comparison of different surface rendering models.
The aim of this study was to compare different representation models of surface-rendered virtual bronchoscopy. 10 consecutive patients with inoperable primary lung tumors underwent thin-section spiral computed tomography. The structures of interest, the tracheobronchial system and anatomical and pathological thoracic structures were segmented using an interactive threshold interval volume-growing segmentation algorithm and visualized with the aid of a color-coded surface rendering method. For virtual bronchoscopy, the tracheobronchial system was visualized using a triangle-surface rendering model, a shaded-surface rendering model and a transparent shaded-surface rendering model. The triangle-surface rendering model allowed optimum detailed spatial representation of the dimensions of extraluminal anatomical and pathological mediastinal structures. As the lumen of the tracheobronchial system was less well defined, the rendering model was of limited use for depiction of the airway surface. The shaded-surface rendering model facilitated an optimum assessment of the airway surface, but the mediastinal structures could not be depicted. The transparent shaded-surface rendering model provides simultaneous adequate to optimum visualization and assessment of the intraluminal airway surface and the extraluminal mediastinal structures as well as a quantitative assessment of the spatial relationship between these structures. Fast data acquisition with a multi-slice detector spiral computed tomography scanner and the use of virtual bronchoscopy with the transparent shaded-surface rendering model obviate the need for time consuming detailed analysis and presentation of axial source images by providing improved the diagnostic imaging of endotracheal and endobronchial diseases and offering a useful alternative to fiberoptic bronchoscopy.
Bronchoscopy↗
Multidetector-row CT cardiac imaging with 4 and 16 slices for coronary CTA and imaging of atherosclerotic plaques.
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Coronary Artery Disease↗
Reproducibility and accuracy of coronary calcium measurements with multi-detector row versus electron-beam CT.
PURPOSE: To methodically evaluate the reproducibility and accuracy of coronary arterial calcification measurements by using spiral multi-detector row and electron-beam computed tomography (CT) with a beating heart phantom. MATERIALS AND METHODS: A phantom was built to mimic a beating heart with coronary arteries and calcified plaques. The simulated vessels moved in a pattern similar to that of a beating heart. The phantom operated at a variety of pulse rates (0-140 beats per minute). The phantom was repeatedly scanned in various positions by using various protocols with electron-beam and multi-detector row CT scanners to assess interexamination variability. Statistical analysis was performed to determine significant differences in interexamination variability for various acquisition protocols. RESULTS: Electrocardiographically (EKG) gated volume coverage with spiral multi-detector row CT (2.5-mm collimation) and overlapping image reconstruction (1-mm increment) was found to significantly improve the reliability of coronary arterial calcium quantification, especially for small plaques (P <.05). Mean interexamination variability was reduced from 35% +/- 6 (SD) (Agatston score, standard electron-beam CT) to 4% +/- 2 (P <.05) (volumetric score, spiral EKG-gated multi-detector row CT). CONCLUSION: By coupling retrospective gating with nearly isotropic volumetric imaging data, spiral multi-detector row CT provides better input data for quantification of coronary arterial calcium volume. Multi-detector row CT allows precise and repeated measurement of coronary arterial calcification, with low interexamination variability.
Calcinosis↗
Multidetector helical CT of the liver for tumor detection and characterization.
Multidetector-row CT (MDCT) scanners have been recently introduced into clinical practice. Major attributes that are improved are the z-axis coverage speed and the longitudinal resolution. These improvements translate into rapid hepatic imaging and allow new imaging protocols. Thin sections can now be used on a routine basis in single-breath-hold technique. This results in improved lesion detection and the nearly isotropic image acquisition provides high-resolution multiplanar reformations. Furthermore, the ability to scan through the entire liver in 10 s or less allows acquisition of two separate sets of CT images of the liver within the time generally regarded as the hepatic arterial dominant phase in monoslice CT; thus, MDCT may demonstrate three clear separate distinct hepatic circulatory phases with a triple-pass technique. Multidetector-row CT with the improvements in morphological and functional information compared with single-slice CT enables a comprehensive approach to hepatic imaging within a single examination.
Carcinoma, Hepatocellular↗
Coronary vessel visualization using true 16-row multi-slice computed tomography technology.
BACKGROUND: Multi-slice computed tomography (MSCT) scanners with retrospective ECG-gating permit visualization of the coronary arteries. Limited spatial and temporal resolution as well as breathing artefacts due to the scan time can cause poor distal vessel segment and side branch visualization. The latest MSCT generation with true 16-detector slices (Sensation 16), Siemens, Forchheim, Germany) provides furthermore improved temporal and spatial resolution, as well as significantly reduced scan time. To assess, whether this technical improvement has also an impact on image quality we conducted the following study. METHODS AND MATERIAL: Sixty-two consecutive patients (33 male, 29 female, mean age 63+/-8 [47-79] years, heart rate after beta-blockade 63+/-7 [45-86] bpm) with suspicion of coronary artery disease (CAD) were examined by cardiac MSCT. Parameter settings were: 0.75 mm collimation, 2.8mm table feed/rotation, caudocranial scan direction, 80 cc contrast media biphasic injection protocol, gantry rotation time 375 ms, temporal resolution 188 ms). Thirteen coronary segments (sgts) were evaluated in each patient (total number: 806 sgts). Image quality of each segment was determined as: excellent--free of motion artefacts, good--mild motion artefacts, relevant artefacts--still diagnostic value, severe calcification and insufficient image quality--not visualized segment. RESULTS: 301/806 (37%) sgts showed excellent and 294/806 (36%) sgts good image quality. Relevant artefacts were seen in 107/806 (13%) sgts, calcifications in 41/806 (5%) sgts. 63/806 (8%) sgts could not be visualized (34 of them (54%) either segment 9 or 10). Diagnostic image quality was achieved in 702/806 (87%) sgts. CONCLUSIONS: Due to true 16-slice technology and faster gantry rotation time MSCT image quality could be improved and allows a visualization of the entire coronary tree. Larger, randomized, catheter-controlled studies have to be conducted to determine, whether this improved visualization also translates into better diagnostic accuracy.
Aged↗
Influence of heart rate on vessel visibility in noninvasive coronary angiography using new multislice computed tomography: experience in 94 patients.
OBJECTIVES: Initial reports indicate that coronary artery lesions might be visualized with high sensitivity and specificity by the use of recently introduced multislice computed tomography (MSCT). Current CT technology offers a temporal resolution of 250 ms. In case of heart rates (HRs) >65 beats/min (bpm), however, the reconstruction software switches from a single-phase algorithm (using data from one heart cycle only) to a biphase algorithm using image data of two consecutive heart cycles, improving temporal resolution to down to 125 ms. Thus, it was the aim of the present study to evaluate the influence of the patients' (pts) HR on image quality expressed by vessel segment visibility. METHODS AND RESULTS: MSCT scans (Somatom VZ) were performed in 94 pts. Ten coronary segments were analyzed in each patient with regard to image quality (RCA: segments [sgts] 1-4, LMS: sgt 5, LAD: sgts 5-8, LCX: sgts 11, 12). A total of 697 of 940 (74.1%) sgts were accurately visualizable (RCA: 244/376 [64.9%], LMS: 94/94 [100%], LAD: 232/283 (82.3%), LCX: 146/188 [77.7%]). Beta-blocker therapy had a significant influence on mean HR (65 pts on beta-blocker, HR 65.1+/-10.7 bpm vs. 29 pts, HR 71.6+/-12.2 bpm, P=.01). A significant inverse correlation between HR and segmental visibility was found (r=-.48, P<.0001), with best visibility in pts with lower HRs (n=14 pts with 10 analyzable sgts, HR 60+/-10.1 vs. n=8 pts with 4 analyzable sgts, HR 79.9+/-6.9, P<.0001). CONCLUSIONS: Our results indicate that vessel visibility is highly dependent on the pts HR. Best vessel visibility was found in pts with HR <65 bpm with single-phase image reconstruction. Thus, it appears to be advisable to evaluate, and if needed, to lower the pts HRs before undergoing MSCT coronary angiography in order to achieve best image quality.
Adult↗
Reliability of differentiating human coronary plaque morphology using contrast-enhanced multislice spiral computed tomography: a comparison with histology.
BACKGROUND: Initial clinical results indicate that multislice spiral computed tomography (MDCT) might be useful for the noninvasive characterization of human coronary plaque morphology by determining tissue density within the lesions. This seems to be of clinical relevance, because coronary artery disease might be detected at an early stage before calcifications occur and noncalcified plaques that may be more likely to rupture could also be visualized noninvasively. The aim of the present study was to evaluate the reliability of contrast-enhanced MDCT in differentiating human atherosclerotic coronary plaque morphology by comparing it with the histopathologic gold standard. METHODS AND RESULTS: Twelve human hearts were scanned postmortem using an MDCT (Somatom Volume Zoom; Siemens, Forchheim, Germany) high-resolution computed tomography scanner to detect atherosclerotic coronary plaques. Density measurements were performed within detected plaque areas. The exact location of each plaque was marked at the surface of the heart to assure accurate histopathologic sectioning of these lesions. The plaques were classified according to a modified Stary classification. Seventeen plaques were identified by MDCT. Six plaques were histopathologically classified as lipid rich (Stary III/IV), 6 plaques as intermediate (Stary V), and 5 plaques as calcific (Stary VII). Lipid-rich plaques had a mean density on MDCT of 42 +/- 22 Hounsfield units (HU), intermediate plaques had a mean density of 70 +/- 21 HU, and calcific plaques had a mean density of 715 +/- 328 HU. ANOVA analysis revealed a significant difference in plaque density between the 3 groups (P < 0.0001). CONCLUSIONS: The comparison with histopathology confirms that tissue density as determined by contrast-enhanced MDCT might be used to differentiate atherosclerotic plaque morphology.
Analysis of Variance↗
Image quality and diagnostic accuracy of 16-slice multidetector spiral computed tomography for the detection of coronary artery disease in elderly patients.
OBJECTIVES: To determine the image quality and diagnostic accuracy of cardiac multislice spiral computed tomography (MSCT) in elderly patients (>65 years old) in comparison to younger patients, this retrospective analysis was performed. METHODS: The catheter-controlled MSCT results from patients older than 65 years of age were compared with the results of younger patients in a cohort of 117 patients with regard to sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and image quality. Fifty-three patients were older than 65 years of age (group 1: 31 men, age range: 72.2 +/- 4.1 years, number of risk factors: 2.6 +/- 1.3, Agatston score: 866 +/- 1090) and 64 were younger (group 2: 45 men, age range: 57.4 +/- 6.1 years, number of risk factors: 2.6 +/- 1.0, Agatston score: 765 +/- 1013). All patients were examined by MSCT (Sensation 16 Speed 4 D; Siemens, Forchheim, Germany, with a gantry rotation time of 375 milliseconds) and invasive coronary angiography. The MSCT results were compared blinded with the results of the coronary angiography with regard to the presence or absence of significant stenosis (>50%) in a 13-segment model. Image quality was assessed on a qualitative scale between 1 (very good) and 5 (insufficient image quality) for each segment. RESULTS: Sensitivity, specificity, PPV, and NPP were not different statistically in both groups (group 1: 0.80/0.96/0.89/0.93 and group 2: 0.89/0.98/0.93/0.97). Three patients (all <65 years old) had to be excluded from analysis because of technical problems. Image quality was significantly better in group 2. Gender, body mass index, number of risk factors, and mean heart rate were not significantly different in either group. CONCLUSIONS: Age has an impact on MSCT image quality but did not hamper diagnostic accuracy. Thus, MSCT is a noninvasive method to detect or rule out coronary artery disease independently of age. These retrospective data have to be confirmed in larger prospective trials.
Age Factors↗
Detection of pulmonary embolism using 16-slice multidetector-row computed tomography: evaluation of different image reconstruction parameters.
OBJECTIVE: To compare different image reconstruction parameters for detecting emboli of the pulmonary arteries according to anatomic levels using 16-slice multidetector-row computed tomography in patients suspected of having an acute pulmonary embolism (PE). METHODS: Sixty-two patients (33 male and 29 female) with a clinically suspected acute PE were included in the present study. Multidetector-row computed tomography scans were performed using 16-mmx0.75-mm collimation. Based on the computed tomography data set, different image reconstruction parameters were used for each patient: axial slice thicknesses (STs) of 0.75, 2, 4, and 6 mm; axial maximum intensity projection (MIP) STs of 4 mm; and coronal STs of 2 and 4 mm. In joint reading fashion, 2 experienced radiologists reviewed examination findings regarding the presence and/or absence of a PE. The reference standard for visualization and detection of PEs was defined using the axial images with a 0.75-mm ST. RESULTS: In 23 of 62 patients, a PE was diagnosed. For main and lobar pulmonary arteries, the sensitivities and specificities were as follows: axial 2-mm images, 1.0/1.0; axial 4-mm images, 1.0/1.0; axial 6-mm images, 0.97/0.99; MIP 4-mm images, 0.95/0.99; coronal 2-mm images, 1.0/1.0; and coronal 4-mm images, 1.0/1.0. Regarding segmental and subsegmental pulmonary arteries, sensitivity and specificity varied: axial 2-mm images, 0.97/1.0; axial 4-mm images, 0.81/0.99; axial 6-mm images, 0.65/0.99; axial MIP 4-mm images, 0.63/0.99; coronal 2-mm images, 0.91/0.99; and coronal 4-mm images, 0.74/0.99. CONCLUSIONS: In detecting segmental and subsegmental PEs, only the axial images with an ST of 2 mm proved to have results comparable with the axial 0.75-mm images. Therefore, thin-slice collimation and ST are mandatory for visualization of segmental and subsegmental PEs in patients suspected of having an acute PE.
Aged↗
Different antigen unmasking techniques lead to significant differences in immunohistochemical staining of Ki-67 (Mib-1) in renal cell carcinomas.
For immunohistochemistry on formalin-fixed, paraffin-embedded specimens adequate pretreatment of the sections to achieve an unmasking of antigenic domains before staining the specimens is necessary. In this study, we compared the effect of microwave and autoclave heating on the expression of the cell proliferation marker Ki-67 (Mib-1) in renal cell carcinomas. A total of 177 formalin-fixed and paraffin-embedded tumor specimens of locally confined renal cell carcinomas with clear cell morphology were investigated. Two different antigen unmasking techniques were used: microwave and autoclave heating. The fraction of Ki-67 positively stained nuclei was determined in APAAP (alkaline phosphatase-antialkaline phosphatase) stained slides. The fraction of Mib-1-labelled cells was significantly higher after autoclave compared to microwave pretreatment (mean value 4.95 vs. 1.43, p<0.001). We recommend the autoclave heating technique for quantitative detection of Ki-67 with the Mib-1 antibody in renal cell carcinomas.
Adult↗