Josef Matthias Kerl
Research interests
-
InterestsMRI, Computed Tomography
Publications
-
1.42Impact points
High-pitch Dual-source Computed Tomography Pulmonary Angiography in Freely Breathing Patients.
Journal of thoracic imaging. 04/2012;
PURPOSE:: To investigate pulmonary arterial (PA) enhancement, image noise, and artifacts related to breathing and heart motion in patients with suspected pulmonary embolism. MATERIALS AND METHODS:: Seventy-six consecutive patients underwent computed tomographic pulmonary angiography (CTPA) in dual-s... [more] PURPOSE:: To investigate pulmonary arterial (PA) enhancement, image noise, and artifacts related to breathing and heart motion in patients with suspected pulmonary embolism. MATERIALS AND METHODS:: Seventy-six consecutive patients underwent computed tomographic pulmonary angiography (CTPA) in dual-source high-pitch mode (pitch 3.0, 100 kV, 180 mAs, 50 mL contrast material) without breathing commands. PA enhancement, image noise, signal to noise ratio, overall image quality, incidence of total or partial interruption of the contrast column in the PAs, and heart motion-related and breathing-related artifacts of the diaphragm and pulmonary structures were recorded. RESULTS:: Mean central and peripheral PA attenuation was 404±104 and 453±119 HU; mean image noise was 11±2 HU; mean examination time was 0.67±0.09 s; and mean dose-length product was 142±31 mGy cm. There were no motion artifacts of the diaphragm or pulmonary vessels related to breathing or heart motion. There was no case of partial or total interruption of the contrast column in the PA tree. No examination was rated nondiagnostic. CONCLUSIONS:: High-pitch dual-source CTPA in freely breathing patients effectively produces images that are free of artifacts related to breathing and cardiac motion. Hence, Valsalva-related artifacts can be eliminated using this technique.
-
2.95Impact points
Image-quality perception as a function of dose in digital radiography.
AJR. American journal of roentgenology. 12/2011; 197(6):1399-403.
The purpose of this article is to determine the degree to which the skin entrance dose could be lowered, by adjusting exposure parameters and filtration, and the subsequent effect on readers' confidence levels of digital radiographs. The study was prospectively performed on a cadaver. Digital ra... [more] The purpose of this article is to determine the degree to which the skin entrance dose could be lowered, by adjusting exposure parameters and filtration, and the subsequent effect on readers' confidence levels of digital radiographs. The study was prospectively performed on a cadaver. Digital radiographs of bones were evaluated and scored on a 9-point scale separately by four radiologists who were blinded to the types of filtration and doses used. The study entailed three phases: phase 1, random dose and filter; phase 2, fixed filter and varying radiation doses (100%, 75%, 50%, and 25% of the standard recommended dose); and phase 3, fixed dose and varying filtration (no filtration, aluminum filter, and aluminum-copper filter). Skin entrance dose was measured using a dosimeter placed on the skin. Differences in scores were tested using a Friedman test. The mean scores given to images with 100%, 75%, 50%, and 25% of the recommended standard dose were 6.18, 6.1, 5.11, and 4.07, respectively. No significant difference was noted between 100%- and 75%-dose images (p = 0.1). A significant difference (p < 0.0001) was noted when we compared the 100%- and 75%-dose images with the 50%- and 25%-dose images. The mean scores given for no filtration, aluminum filtration, and aluminum-copper filtration were 5.67, 5.43, and 5.18, respectively. No significant difference between no filtration and aluminum filtration (p = 0.411) was noted. A significant difference was detected between no filtration and aluminum-copper filtration (p = 0.012). The combination of an aluminum filter and a 75% standard dose achieved a 31.1% reduction in skin entrance dose. It is possible to achieve a 31.1% reduction in skin entrance dose for imaging bony structures by using 75% of the standard dose and aluminum filtration without significantly affecting image quality.
-
2.65Impact points
Intravenous contrast material administration at high-pitch dual-source CT pulmonary angiography: Test bolus versus bolus-tracking technique.
European journal of radiology. 10/2011;
PURPOSE: To compare test bolus and bolus tracking for the determination of scan delay of high-pitch dual-source CT pulmonary angiography in patients with suspected pulmonary embolism using 50ml of contrast material. MATERIALS AND METHODS: Data of 80 consecutive patients referred for CT pulmonary ang... [more] PURPOSE: To compare test bolus and bolus tracking for the determination of scan delay of high-pitch dual-source CT pulmonary angiography in patients with suspected pulmonary embolism using 50ml of contrast material. MATERIALS AND METHODS: Data of 80 consecutive patients referred for CT pulmonary angiography were evaluated. All scans were performed on a 128-channel dual-source CT scanner with a high-pitch protocol (pitch 3.0, 100kV, 180mAs). Contrast enhancement was achieved by injecting 50ml of iomeprol followed by a saline chaser of 50ml injected at a rate of 4ml/s. The scan delay was determined using either the test bolus (n=40) or bolus tracking (n=40) technique. Test bolus required another 15ml CM to determine time to peak enhancement of the contrast bolus within the pulmonary trunk. Attenuation profiles in the pulmonary trunk and on segmental level as well as in the ascending aorta were measured to evaluate the timing techniques. Additionally, overall image quality was evaluated. RESULTS: In all patients an adequate and homogeneous contrast enhancement of more than 250HU was achieved in the pulmonary arteries. No statistically significant difference between test bolus and bolus tracking was found regarding attenuation of the pulmonary arteries or overall image quality. However, using bolus tracking 15ml CM less was injected. CONCLUSION: A homogeneous opacification of the pulmonary arteries and sufficient image quality can be achieved with both the bolus tracking and test bolus techniques with significant lower contrast doses compared to conventional contrast material injection protocols.
-
3.59Impact points
High-pitch dual-source CT angiography of the whole aorta without ECG synchronisation: initial experience.
European radiology. 09/2011; 22(1):129-37.
To investigate the feasibility, image quality and radiation dose for high-pitch dual-source CT angiography (CTA) of the whole aorta without ECG synchronisation. Each group of 40 patients underwent CTA either on a 16-slice (group 1) or dual-source CT device with conventional single-source (group 2) o... [more] To investigate the feasibility, image quality and radiation dose for high-pitch dual-source CT angiography (CTA) of the whole aorta without ECG synchronisation. Each group of 40 patients underwent CTA either on a 16-slice (group 1) or dual-source CT device with conventional single-source (group 2) or high-pitch mode with a pitch of 3.0 (group 3). The presence of motion or stair-step artefacts of the thoracic aorta was independently assessed by two readers. Subjective and objective scoring of motion and artefacts were significantly reduced in the high-pitch examination protocol (p < 0.05). The imaging length was not significantly different, but the imaging time was significantly (p < 0.001) shorter in the high-pitch group (12.2 vs. 7.4 vs. 1.7 s for groups 1, 2 and 3). The ascending aorta and the coronary ostia were reliably evaluable in all patients of group 3 without motion artefacts as well. High-pitch dual-source CT angiography of the whole aorta is feasible in unselected patients. As a significant advantage over regular pitch protocols, motion-free imaging of the aorta is possible without ECG synchronisation. Thus, this CT mode bears potential to become a standard CT protocol before trans-catheter aortic valve implantation (TAVI).
-
1.27Impact points
Dual energy CT for the assessment of reperfused chronic infarction - a feasibility study in a porcine model.
Acta radiologica (Stockholm, Sweden : 1987). 08/2011; 52(8):834-9.
BACKROUND: Detection of myocardial infarction has been the focus of considerable research over the past few decades. Recently developed dual source computed tomography (DSCT) scanners with dual energy mode have been used to detect myocardial infarction, but the studies on this topic are few. To eval... [more] BACKROUND: Detection of myocardial infarction has been the focus of considerable research over the past few decades. Recently developed dual source computed tomography (DSCT) scanners with dual energy mode have been used to detect myocardial infarction, but the studies on this topic are few. To evaluate the feasibility and performance of dual energy CT (DECT) during arterial phase in coronary CT angiography for the detection of chronic infarction compared with late enhancement MRI (LE-MRI) and histopathology in a porcine model of reperfused myocardial infarction. Myocardial infarctions were induced by 30 min occlusion of the proximal left anterior descending coronary artery in eight minipigs. DECT, post-contrast LE-MRI and histopathology were performed 60 days after infarct induction. The CT scan was performed in dual energy mode using a dedicated protocol. Myocardial iodine distribution was superimposed as color maps on grey scale multiplanar reformats of the heart. Two radiologists in consensus interpreted all imaging studies for presence of gadolinium uptake at LE-MRI reduced iodine content at DECT and hypoenhanced areas in the initial 100 kV coronary CT angiography images that were acquired during the DECT-acquisition. Results were compared with histopathology. Based on evaluable segments, DECT showed a sensitivity and specificity of 0.72 and 0.88; LE-MRI showed a sensitivity and specificity of 0.78 and 0.92; and the 100 kV data-set of the DECT scan showed a sensitivity and specificity of 0.60 and 0.93, respectively, for the detection of histological proved ischemia. DECT during arterial phase coronary CT angiography, which is ordinarily used for coronary artery evaluation, is feasible for the detection of a chronic reperfused myocardial infarction.
-
6.34Impact points
Evaluation of heavily calcified vessels with coronary CT angiography: comparison of iterative and filtered back projection image reconstruction.
Radiology. 06/2011; 260(2):390-9.
To prospectively compare traditional filtered back projection (FBP) and iterative image reconstruction for the evaluation of heavily calcified arteries with coronary computed tomography (CT) angiography. The study had institutional review board approval and was HIPAA compliant. Written informed cons... [more] To prospectively compare traditional filtered back projection (FBP) and iterative image reconstruction for the evaluation of heavily calcified arteries with coronary computed tomography (CT) angiography. The study had institutional review board approval and was HIPAA compliant. Written informed consent was obtained from all patients. Fifty-five consecutive patients (35 men, 20 women; mean age, 58 years ± 12 [standard deviation]) with Agatston scores of at least 400 underwent coronary CT angiography and cardiac catheterization. Image data were reconstructed with both FBP and iterative reconstruction techniques with corresponding cardiac algorithms. Image noise and subjective image quality were compared. To objectively assess the effect of FBP and iterative reconstruction on blooming artifacts, volumes of circumscribed calcifications were measured with dedicated volume analysis software. FBP and iterative reconstruction series were independently evaluated for coronary artery stenosis greater than 50%, and their diagnostic accuracy was compared, with cardiac catheterization as the reference standard. Statistical analyses included paired t tests, Kruskal-Wallis analysis of variance, and a modified McNemar test. Image noise measured significantly lower (P = .011-.035) with iterative reconstruction instead of FBP. Image quality was rated significantly higher (P = .031 and .042) with iterative reconstruction series than with FBP. Calcification volumes measured significantly lower (P = .019 and .026) with iterative reconstruction (44.3 mm(3) ± 64.7 and 46.2 mm(3) ± 68.8) than with FBP (54.5 mm(3) ± 69.5 and 56.3 mm(3) ± 72.5). Iterative reconstruction significantly improved some measures of per-segment diagnostic accuracy of coronary CT angiography for the detection of significant stenosis compared with FBP (accuracy: 95.9% vs 91.8%, P = .0001; specificity: 95.8% vs 91.2%, P = .0001; positive predictive value: 76.9% vs 61.1%, P = .0001). Iterative reconstruction reduces image noise and blooming artifacts from calcifications, leading to improved diagnostic accuracy of coronary CT angiography in patients with heavily calcified coronary arteries.
-
2.95Impact points
Perfusion CT of head and neck cancer: effect of arterial input selection.
AJR. American journal of roentgenology. 06/2011; 196(6):1374-80.
The purpose of this study is to evaluate the effect of arterial input selection on perfusion CT parameters of head and neck tumors. Perfusion calculations were done for 50 cases using deconvolution-based software. Peak enhancement values of the ipsilateral internal carotid artery (ICA) and external ... [more] The purpose of this study is to evaluate the effect of arterial input selection on perfusion CT parameters of head and neck tumors. Perfusion calculations were done for 50 cases using deconvolution-based software. Peak enhancement values of the ipsilateral internal carotid artery (ICA) and external carotid artery (ECA) were recorded. Blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability surface area product were calculated using ipsilateral ECA, ipsilateral ICA, and contralateral ICA as input arteries. Values were compared using Wilcoxon's matched pair test and Pearson's correlation coefficients (r). A highly significant correlation was observed between peak enhancement values of the ICA and ECA (r = 0.97; p < 0.0001). A high correlation was observed between perfusion calculations obtained using ipsilateral ICA and ECA (BF, r = 0.98; BV, r = 0.92; MTT, r = 0.91; and permeability surface area product, r = 0.89), ipsilateral and contralateral ICA (BF, r = 0.97; BV, r = 0.95; MTT, r = 0.93; and permeability surface area product, r = 0.89), as well as left and right ICA (BF, r = 0.97; BV, r = 0.95; MTT, r = 0.94; and permeability surface area product, r = 0.88). All correlations were statistically significant (p < 0.0001). No significant differences were observed between perfusion calculations obtained using ipsilateral ICA versus ECA, ipsilateral versus contralateral ICA, or left versus right ICA (p > 0.05). Arterial input selection has no significant effect on perfusion CT calculation of head and neck cancer. For standardization and simplification of postprocessing, we recommend the use of the ICA instead of the ECA as the arterial input because of its better visualization, perpendicular course, and larger caliber, all of which decrease partial volume effects.
-
2.65Impact points
Effect of contrast material on image noise and radiation dose in adult chest computed tomography using automatic exposure control: a comparative study between 16-, 64- and 128-slice CT.
European journal of radiology. 06/2011; 79(2):e128-32.
To determine the difference in radiation dose between non-enhanced (NECT) and contrast-enhanced (CECT) chest CT examinations contributed by contrast material with different scanner generations with automatic exposure control (AEC). Each 42 adult patients received a NECT and CECT of the chest in one ... [more] To determine the difference in radiation dose between non-enhanced (NECT) and contrast-enhanced (CECT) chest CT examinations contributed by contrast material with different scanner generations with automatic exposure control (AEC). Each 42 adult patients received a NECT and CECT of the chest in one session on a 16-, 64- or 128-slice CT scanner with the same scan protocol settings. However, AEC technology (Care Dose 4D, Siemens) underwent upgrades in each of the three scanner generations. DLP, CTDIvol and image noise were compared. Although absolute differences in image noise were very small and ranged between 10 and 13 HU for NECT and CECT in median, the differences in image noise and dose (DLP: 16-slice:+2.8%; 64-slice:+3.9%; 128-slice:+5.6%) between NECT and CECT were statistically significant in all groups. Image noise and dose parameters were significantly lower in the most recent 128-slice CT generation for both NECT and CECT (DLP: 16-slice:+35.5-39.2%; 64-slice:+6.8-8.5%). The presence of contrast material lead to an increase in dose for chest examinations in three CT generations with AEC. Although image noise values were significantly higher for CECT, the absolute differences were in a range of 3 HU. This can be regarded as negligible, thus indicating that AEC is able to fulfill its purpose of maintaining image quality. However, technological developments lead to a significant reduction of dose and image noise with the latest CT generation.
-
3.59Impact points
Dose and image quality at CT pulmonary angiography-comparison of first and second generation dual-energy CT and 64-slice CT.
European radiology. 05/2011; 21(10):2139-47.
To compare dose and image quality of 64-slice, first and second generation dual-energy CT (DECT) for CT pulmonary angiography (CTPA). Totally 120 patients, 30 in each group, underwent CTPA on a first generation (group 1: single-energy, 120 kV/145 mAs; group 2: DE, 140/80 kV, 70/350 mAs) or second ge... [more] To compare dose and image quality of 64-slice, first and second generation dual-energy CT (DECT) for CT pulmonary angiography (CTPA). Totally 120 patients, 30 in each group, underwent CTPA on a first generation (group 1: single-energy, 120 kV/145 mAs; group 2: DE, 140/80 kV, 70/350 mAs) or second generation dual-source DECT device (group 3: DE, 100/Sn140 kV, 120/102 mAs; group 4: DE, 80/Sn140 kV, 202/86 mAs). CTDIvol, DLP, background noise (BN), thorax diameter and attenuation in the pulmonary trunk were compared. Thorax diameter and attenuation in the pulmonary trunk did not differ significantly (p > 0.4 and >0.19) between the groups. Mean CTDIvol and DLP were significantly lower (p < 0.003) in group 4 (6.2 ± 1.6 mGy/170 ± 41 mGycm) compared to group 1 (8.5 ± 2.6 mGy/235 ± 117 mGycm), group 2 (9.2 ± 3.3 mGy/224 ± 122 mGycm) and group 3 (8.7 ± 2.8 mGy/246 ± 86 mGycm). BN was significantly lower (p < 0.0001) in group 4 (12 ± 3 HU) and group 1 (13 ± 6 HU) compared to group 3 and 2 (16 ± 6 HU and 23 ± 9). The use of second generation DECT in 80/Sn140 kV configuration allows for significant dose reduction with image quality similar to 120 kV CTPA.
-
4.85Impact points
Dual-Energy CT of Head and Neck Cancer: Average Weighting of Low- and High-Voltage Acquisitions to Improve Lesion Delineation and Image Quality-Initial Clinical Experience.
Investigative radiology. 05/2011;
OBJECTIVES:: Mixing low- and high-voltage acquisitions of dual-energy CT (DECT) scan using different weighting factors leads to differences in attenuation values and image quality. The aim of this work was to evaluate whether average weighting of DECT acquisitions could improve delineation of head a... [more] OBJECTIVES:: Mixing low- and high-voltage acquisitions of dual-energy CT (DECT) scan using different weighting factors leads to differences in attenuation values and image quality. The aim of this work was to evaluate whether average weighting of DECT acquisitions could improve delineation of head and neck cancer and image quality. MATERIALS AND METHODS:: Among 60 consecutive patients who underwent DECT scan of the head and neck, 35 patients had positive findings and were included in the study. Images were reconstructed as pure 80 kVp, pure Sn140 kVp, and weighted-average (WA) image datasets from low- and high-voltage acquisitions using 3 different weighting factors (0.3, 0.6, 0.8) incorporating 30%, 60%, 80% from the 80 kVp data, respectively. Lesion contrast-to-noise ratio (CNR), attenuation measurements, and objective noise were compared between different image datasets. Two independent blinded radiologists subjectively rated the overall image quality of each image dataset on a 5-point grading scale comprising lesion delineation, image sharpness, and subjective noise. RESULTS:: Mean venous and tumor enhancement and muscle attenuation increased stepwise with decreasing tube voltage from Sn140 kVp through 80 kVp. CNR increased significantly from Sn140 kVp to weighting factor 0.3 then to weighting factor 0.6 (P < 0.0001). The increase in CNR from weighting factor 0.6 to 0.8 then to 80 kVp was nonsignificant (P = 1.00). The 0.6 weighted-average image dataset received the best image quality score by the 2 readers. CONCLUSION:: Mixing the DE data from the 80 kVp and Sn140 kVp tubes using weighting factor 0.6 (60% from 80 kVp data) could improve lesion CNR and subjective overall image quality (including lesion delineation). This weighting factor was significantly superior to the 0.3 weighting factor which simulates standard 120 kVp acquisition.
-
3.59Impact points
Accuracy of coronary artery stenosis detection with CT versus conventional coronary angiography compared with composite findings from both tests as an enhanced reference standard.
European radiology. 05/2011; 21(9):1895-903.
To prospectively compare the accuracy of coronary CT angiography (CCTA) and conventional coronary angiography (CCA) for stenosis detection using composite findings from both tests as an enhanced reference standard. One hundred thirteen patients underwent CCTA and CCA. Per-segment and per-patient acc... [more] To prospectively compare the accuracy of coronary CT angiography (CCTA) and conventional coronary angiography (CCA) for stenosis detection using composite findings from both tests as an enhanced reference standard. One hundred thirteen patients underwent CCTA and CCA. Per-segment and per-patient accuracy of CCTA compared with initial CCA interpretation were determined. Angiographers were then unblinded to the CCTA results and re-evaluation of the CCA studies was performed with knowledge of CCTA findings, which was used as an enhanced reference standard to compare the diagnostic accuracy of CCTA versus CCA. When using the enhanced reference standard instead of initial CCA interpretation, CCTA accuracy for identifying segments (patients) with ≥50% stenosis increased from 97.7% (96.5%) to 98.1% (98.2%), sensitivity from 90.5% (100%) to 90.8% (100%), and specificity from 98.4% (94.3%) to 98.9% (97.1%). CCTA identified six segments and two patients with stenoses ≥50% missed on initial CCA interpretation. Compared with the enhanced reference standard the accuracies of CCTA and of initial CCA interpretation were not different (p = 0.87). CCTA compares favourably with CCA for stenosis detection. Use of a composite reference standard combining findings from both tests can control for the effect of false-negative CCA results when evaluating the accuracy of CCTA.
-
3.59Impact points
Dual energy CT pulmonary blood volume assessment in acute pulmonary embolism - correlation with D-dimer level, right heart strain and clinical outcome.
European radiology. 04/2011; 21(9):1914-21.
To investigate the role of perfusion defect (PD) size on dual energy CT pulmonary blood volume assessment as predictor of right heart strain and patient outcome and its correlation with d-dimer levels in acute pulmonary embolism (PE). 53 patients with acute PE who underwent DECT pulmonary angiograph... [more] To investigate the role of perfusion defect (PD) size on dual energy CT pulmonary blood volume assessment as predictor of right heart strain and patient outcome and its correlation with d-dimer levels in acute pulmonary embolism (PE). 53 patients with acute PE who underwent DECT pulmonary angiography were retrospectively analyzed. Pulmonary PD size caused by PE was measured on DE iodine maps and quantified absolutely (VolPD) and relatively to the total lung volume (RelPD). Signs of right heart strain (RHS) on CT were determined. Information on d-dimer levels and readmission for recurrent onset of PE and death was collected. D-dimer level was mildly (r = 0.43-0.47) correlated with PD size. Patients with RHS had significantly higher VolPD (215 vs. 73 ml) and RelPD (9.9 vs. 2.9%) than patients without RHS (p < 0.003). There were 2 deaths and 1 readmission due of PE in 18 patients with >5% RelPD, while no such events were found for patients with <5% RelPD. Pulmonary blood volume on DECT in acute PE correlates with RHS and appears to be a predictor of patient outcome in this pilot study.
-
4.85Impact points
Dual-energy computed tomography for the detection of late enhancement in reperfused chronic infarction: a comparison to magnetic resonance imaging and histopathology in a porcine model.
Investigative radiology. 03/2011; 46(7):450-6.
To evaluate the performance of late enhancement dual-energy CT (LE-DECT) for the detection of infarcted myocardium as compared with 1.5-T late enhancement magnetic resonance imaging (LE-MRI) in a porcine model of reperfused chronic myocardial infarction (MI), using histopathology as standard of refe... [more] To evaluate the performance of late enhancement dual-energy CT (LE-DECT) for the detection of infarcted myocardium as compared with 1.5-T late enhancement magnetic resonance imaging (LE-MRI) in a porcine model of reperfused chronic myocardial infarction (MI), using histopathology as standard of reference. In 8 healthy minipigs, MI was induced by 30-minute balloon occlusion of the left anterior descending coronary artery. Sixty-one ± 4 days after left anterior descending coronary artery occlusion, LE-DECT was performed 5, 10, and 15 minutes subsequent to contrast material injection. Therefore, a dual-source CT scanner (Somatom Definition, Siemens Healthcare, Forchheim, Germany) was used in dual-energy mode with the following protocol: tube potential/current 140 kV/95 mAs on tube A and 100 kV/165 mAs on tube B, collimation 2 × 32 × 0.6 mm, 1.5 mL/kg contrast material injected at 3 to 4 mL/s. Myocardial iodine distribution was calculated from the dual-energy data and superimposed on the gray scale multiplanar reformats of the heart in short-axis view. Fifty ± 12 minutes after LE-DECT imaging, 1.5-T LE-MRI (Magnetom Avanto, Siemens Healthcare, Forchheim, Germany) was performed 10 minutes successive to injection of contrast material using phase-sensitive inversion recovery sequences. For all pigs investigated, 2,3,5-triphenyltetrazolium chloride staining and histopathology of stained-tissue samples were acquired. Two experienced radiologists assessed all imaging studies in a random manner and were blinded to the results of the other techniques for the presence of late enhancement (LE). The American Heart Association 17-segment model was used to compare the results of LE-DECT, 100 kV grayscale LE images, LE-MRI, and histopathology. Size of MI was calculated for histopathological findings, LE-MRI, LE-DECT, and 100 kV grayscale LE images 10 minutes after contrast agent injection. Agreement between infarct size assessed with imaging modalities and histopathology was evaluated with Bland-Altman analysis. Of the 136 myocardial segments in 8 minipigs, histopathology found MI in 27 segments. Diagnostic per-segment sensitivities and specificities for 100 kV grayscale LE images, LE-DECT images, and MR images obtained 10 minutes after contrast agent injection for both the readers were 0.62, 0.77, 0.79 and 0.97, 0.92, 0.94, respectively. Although sensitivities were higher for LE-DECT and LE-MRI than for 100 kV grayscale images, no statistically significant difference for the diagnostic accuracies of 100 kV grayscale LE images, LE-DECT images, and MR images (0.9, 0.89, 0.9) existed 10 minutes successive to contrast agent injection (all P > 0.05). Infarct size for LE-MRI, LE-DECT, and 100 kV grayscale LE images correlated well with histopathological findings (r = 0.97, 0.96, and 0.94; all P < 0.01). This feasibility study shows a high accuracy and a good correlation of LE-DECT and LE-MRI to histopathology for the detection of LE in a porcine model of reperfused chronic MI.
-
3.59Impact points
Dose levels at coronary CT angiography--a comparison of Dual Energy-, Dual Source- and 16-slice CT.
European radiology. 03/2011; 21(3):530-7.
To compare the dose estimates and image quality of Dual Energy CT (DECT), Dual Source CT (DSCT) and 16-slice CT for coronary CT angiography (cCTA). Sixty-eight patients were examined with 16 - slice MDCT (group 1), 68 patients with DSCT (group 2) and 68 patients using DSCT in dual energy mode (DECT ... [more] To compare the dose estimates and image quality of Dual Energy CT (DECT), Dual Source CT (DSCT) and 16-slice CT for coronary CT angiography (cCTA). Sixty-eight patients were examined with 16 - slice MDCT (group 1), 68 patients with DSCT (group 2) and 68 patients using DSCT in dual energy mode (DECT group 3). CT dose index volume, dose length product, effective dose, signal-to-noise, and contrast-to-noise ratio were compared. Subjective image quality was rated by two observers, blinded to technique. The mean estimated radiation dose of all patients investigated on a 16 - slice MDCT was 12 ± 3.59 mSv, for DSCT in single energy 9.8 ± 4.77 mSv and for DECT 4.54 ± 1.87 mSv. Dose for CTA was significantly lower in group 3 compared to group 1 and 2. The image noise was significantly lower in Group 2 in comparison to group 1 and group 3. There was no significant difference in diagnostic image quality comparing DECT and DSCT. cCTA shows better dose levels at both DECT and DSCT compared to 16-slice CT. Further, DECT delivers significantly less dose than regular DSCT or single source single energy cCTA while maintaining diagnostic image quality.
-
3.59Impact points
Low-dose computed tomography of the paranasal sinus and facial skull using a high-pitch dual-source system--first clinical results.
European radiology. 01/2011; 21(1):107-12.
Computed tomography (CT) of the paranasal sinus is the standard diagnostic tool for a wide range of indications in mostly younger patients. This study aims to assess the image quality of CT of the sinus by using a high-pitch dual-source technique with special regard to the radiation dose. Examinatio... [more] Computed tomography (CT) of the paranasal sinus is the standard diagnostic tool for a wide range of indications in mostly younger patients. This study aims to assess the image quality of CT of the sinus by using a high-pitch dual-source technique with special regard to the radiation dose. Examinations were performed on a second-generation dual-source CT with a pitch factor of 3.0 (dual-source mode). Images were compared with those with a pitch factor of 0.9 on the same system (single-source mode) and with those of 16-slice CT. Image quality was evaluated by four blinded readers using a 5-point scale (1=poor, 5=excellent). Comparison of the dose length product (DLP) was used to estimate radiation exposure. Seventy-three consecutive patients underwent imaging with the proposed CT protocols. The viewers rated the image quality of the dual-source image sets as nearly as good (3.62) as the single-source images on the same device (4.18) and those on 16-slice CT (3.7). DLP was cut to half of the dose [51 mGycm vs. 97.8 mGycm vs. 116.9 mGycm (p<0.01)]. Using the proposed dual-source mode when examining the paranasal sinus, diagnostic image quality can be achieved while drastically lowering the patient's radiation exposure.
-
1.42Impact points
64-slice multidetector-row computed tomography in the diagnosis of coronary artery disease: interobserver agreement among radiologists with varied levels of experience on a per-patient and per-segment basis.
Journal of thoracic imaging. 12/2010; 27(1):29-35.
To assess the interobserver variability of 4 radiologists with different levels of experience in the evaluation of 64-slice coronary computed tomographic angiography (cCTA). Two board-certified radiologists with 10 and 8 years of experience in reading cCTA and 2 radiology residents, 1 with 3 years o... [more] To assess the interobserver variability of 4 radiologists with different levels of experience in the evaluation of 64-slice coronary computed tomographic angiography (cCTA). Two board-certified radiologists with 10 and 8 years of experience in reading cCTA and 2 radiology residents, 1 with 3 years of experience in reading cCTA and 1 with experience in reading general computed tomographic scans but without dedicated cCTA training, participated in the study. All the observers independently analyzed 50 cCTA studies for signs of coronary artery disease (stenosis of 0%, ≤49%, 50% to 74%, 75% to 99%, or 100%). Diagnostic accuracy of the 4 readers for stenosis detection on cCTA was compared with that of conventional angiography on a per-segment and per-patient basis. No patients, vessels, or segments were excluded from analysis. On a per-segment basis, correlation between cCTA and invasive coronary angiography was good for readers with more than 10 (r=0.75), more than 8 (r=0.75), and more than 3 (r=0.73) years of cCTA experience. The correlation coefficient was poor (r=0.39) for the untrained reader. Sensitivity was not significantly (P=0.56) different between observers with more than 8 and more than 10 years of experience but was significantly (P>0.05) lower for the reader with less than 3 years experience and for the untrained reader. However, we found no significant difference in overall diagnostic accuracy on a per-patient (P=0.86) and on a per-segment level (P=0.72) among the 4 readers. The level of experience significantly influences the sensitivity of coronary artery stenosis detection at cCTA, and thus highlights the need for dedicated training in cCTA interpretation.
-
2.65Impact points
Lung perfusion analysis with dual energy CT in patients with suspected pulmonary embolism--influence of window settings on the diagnosis of underlying pathologies of perfusion defects.
European journal of radiology. 10/2010; 80(3):e476-82.
On lung perfusion analysis with dual energy CT (DECT) in patients with suspected pulmonary embolism (PE) commonly three patterns of perfusion defects (PD) are observed: wedge-shaped, circumscribed but not wedge-shaped, and patchy. We investigated the influence of different window settings on the ide... [more] On lung perfusion analysis with dual energy CT (DECT) in patients with suspected pulmonary embolism (PE) commonly three patterns of perfusion defects (PD) are observed: wedge-shaped, circumscribed but not wedge-shaped, and patchy. We investigated the influence of different window settings on the identification of the underlying pathologies for these types of PD. 3724 segments in 196 consecutive patients who underwent pulmonary DECT angiography for clinically suspected acute PE were analyzed. Iodine distribution in the lung parenchyma was calculated from the dual energy data and displayed as color map in axial, sagittal and coronal view. Afterwards, lung and angiography window were applied separately and assessed for pulmonary embolism and pathologies of the lung parenchyma. 1420 segments in 141 patients showed PD, of which 276 were wedge-shaped, 287 circumscribed and 857 patchy. Circumscribed PD were associated in 99% with interstitial or alveolar fluid collections and in 1% with located bullae. Patchy PD were associated in 65% with emphysematous or fibrotic changes, in 38% with diffuse infiltrations or interstitial fluid collections and in 0.2% with PE. The underlying pathologies for wedge-shaped PD were in 78% PE, in 3% tumors compressing pulmonary arteries, in another 3% located bullae and in further 3% infiltrations. 13% (n=15) of the segments in this group did not show vascular or parenchymal pathologies, but in 80% (n=10) of these cases patients had PE in another segment. Totally n=6 of wedge-shaped PD in 5 patients remained with unclear direct cause. Whereas patchy and circumscribed PD are almost exclusively associated with pathologies of the lung parenchyma, wedge-shaped PD are mostly associated with PE. For a small number of wedge-shaped PD the underlying cause cannot be detected with DECT. Very small peripherally situated micro-emboli may be discussed as a reason. However, prospective trials are needed to clarify the value of this finding.
-
2.65Impact points
Triphasic contrast injection improves evaluation of dual energy lung perfusion in pulmonary CT angiography.
European journal of radiology. 10/2010; 80(3):e483-7.
Lung perfusion analysis at dual energy CT (DECT) is sensitive to beam hardening artifacts from dense contrast material (CM). We compared two scan and four CM injection protocols in terms of severity of artifacts and attenuation levels in the thoracic vessels. Data of 120 patients who had undergone d... [more] Lung perfusion analysis at dual energy CT (DECT) is sensitive to beam hardening artifacts from dense contrast material (CM). We compared two scan and four CM injection protocols in terms of severity of artifacts and attenuation levels in the thoracic vessels. Data of 120 patients who had undergone dual source dual energy CT pulmonary angiography for suspected acute pulmonary embolism were evaluated. Group 1 (n=30) was scanned in craniocaudal direction using 64×0.6 mm collimation; groups 2-4 (n=30 each) were scanned in caudocranial direction using 14×1.2 mm collimation. In groups 1-3 biphasic injection protocols with different amounts of CM and NaCl were investigated. In group 4 a split-bolus protocol with an initial CM bolus of 50 ml followed by 30 ml of a 70%:30% NaCl/CM mixture and a 50 ml NaCl chaser bolus was used. CT density values in the subclavian vein (SV), superior vena cava (SVC), pulmonary artery tree (PA), and the descending aorta (DA) were measured. Artifacts arising from the SV and SVC on DE pulmonary iodine distribution map were rated on a scale from 1 to 5 (1=fully diagnostic; 5=non-diagnostic) by two blinded readers. In protocol 4 mean attenuation in the SV (645±158 HU) and SVC (389±114 HU) were significantly lower compared to groups 1-3 (p<0.002). Artifacts in group 4 (1.1±0.4 and 1.5±0.7 for the SV and SVC, respectively) were rated significantly less severe compared to group 1 (3.2±1.0 and 3.0±1.1), 2 (2.6±1.1 and 2.3±1.0) and 3 (1.9±0.9 and 1.9±0.7) (p<0.01 for all), whereas no significant difference was found between groups 1 and 2 for the subclavian vein (p=0.07). Attenuation in the PA was also significantly lower in group 4 (282±116 HU) compared to group 1 (397±137 HU), group 2 (376±115 HU) and group 3 (311±104 HU), but still on a diagnostic level. Split-bolus injection provides sufficient attenuation for pulmonary DECT angiography while beam hardening artifacts arising from high density contrast material in the thoracic vessels can be reduced significantly.
-
2.95Impact points
Dual-energy CT for the assessment of chronic myocardial infarction in patients with chronic coronary artery disease: comparison with 3-T MRI.
AJR. American journal of roentgenology. 09/2010; 195(3):639-46.
The purpose of this article is to compare the performance of dual-energy CT with that of 3-T MRI with late enhancement for the detection of chronic myocardial infarction during first-pass coronary CT angiography (CTA). Thirty-six patients underwent coronary CTA for the assessment of coronary bypass ... [more] The purpose of this article is to compare the performance of dual-energy CT with that of 3-T MRI with late enhancement for the detection of chronic myocardial infarction during first-pass coronary CT angiography (CTA). Thirty-six patients underwent coronary CTA for the assessment of coronary bypass graft patency on a first-generation dual-source CT scanner in dual-energy mode. Gray-scale images (100 kV, 140 kV, and blended virtual 120 kV) were assessed for areas of hypodense myocardium during the arterial phase. In addition, a color-coded map of myocardial iodine distribution was calculated from the dual-energy data for perfusion analysis. Dual-energy CT data were compared with data from 3-T MRI with late enhancement, which served as the reference standard for scar detection using the American Heart Association's 17-segment model of the left ventricle. One hundred one (17%) of 612 myocardial segments in 22 (61%) of 36 patients showed late enhancement on MRI. Although myocardial iodine mapping was prone to artifacts, mostly arising from sternal wires (70% sensitivity), 100-kV gray-scale images showed the highest sensitivity (80%) for the detection of myocardial scar. Blended virtual 120-kV images with lower noise and higher resolution had the best diagnostic accuracy (77% sensitivity, 97% specificity, 85% positive predictive value, 96% negative predictive value, and 94% accuracy). Detection of chronic myocardial infarction on color-coded iodine distribution analysis with first-generation dual-energy CT is impeded by thoracic metallic devices. This group of patients benefits more from adequate blending of high- and low-kilovoltage gray-scale images. Further technical improvements are desirable to lower artifact burden and improve sensitivity on myocardial iodine distribution mapping.
-
2.95Impact points
In vitro evaluation of metallic coronary artery stents with 64-MDCT using an ECG-gated cardiac phantom: relationship between in-stent visualization, stent type, and heart rate.
AJR. American journal of roentgenology. 03/2010; 194(3):W256-62.
The purpose of this study was to assess the accuracy of 64-MDCT in the visualization of different coronary artery stents and in the appraisal of in-stent stenosis. MATERIALS AND METhODS: Five different coronary stent types with three diameters (2.5, 3.0, and 4.0 mm) were analyzed using anthropomorph... [more] The purpose of this study was to assess the accuracy of 64-MDCT in the visualization of different coronary artery stents and in the appraisal of in-stent stenosis. MATERIALS AND METhODS: Five different coronary stent types with three diameters (2.5, 3.0, and 4.0 mm) were analyzed using anthropomorphic dynamic cardiac phantom. All stents were mounted on polyurethane sticks of defined outer diameter and contained a default concentric stenosis of 50% each. Imaging was performed at four different heart rates (no motion, 60 beats/min, 75 beats/min, and 90 beats/min). Apparent stent diameter, degree of stenosis, in-stent attenuation, and diagnostic accuracy were assessed. A significant (p < 0.05) overestimation of the degree of stenosis (41.1% +/- 41.4%), underestimation of the stent lumen (-42.7% +/- 41.4%), and increase in in-stent attenuation (36.6 +/- 29.2 HU) were observed for all stents and heart rates. In-stent stenosis > 50% was detected with an overall sensitivity of 88.9% (95% CI, 75.9-96.3%) and an overall specificity of 51.1% (95% CI, 35.8-66.3%) by observer 1 and with an overall sensitivity of 86.7% (95% CI, 73.2-94.9%) and an overall specificity of 57.8% (95% CI, 42.2-72.3%) by observer 2. A trend toward higher specificity was observed for increasing stent diameter, however, without reaching statistical significance (p = 0.63). In an experimental setting, 64-MDCT allows a reliable detection of instent stenosis but significantly overestimates the actual degree of stenosis. Within the range of physiologic heart rates, diagnostic accuracy is restricted by spatial, not temporal, resolution.
Following (8)
-
Markus Hambek
Goethe-Universität Frankfurt am Main -
Nour-Eldin A Nour-Eldin
Johann Wolfgang Goethe University, Frankfurt University Hospital -
Garrett W Rowe
The Medical University of South Carolina -
Matthias Renker
Kerckhoff Heart and Thorax Center, Bad Nauheim -
Jijo Paul
J.W Goethe University hospital
Topics (3)
