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Biomedical subjects

Marc Dewey

Publications and source records attributed to Marc Dewey.

At least 19 recordsLinked to original sources
PubMed2007

Multislice computed tomography: angiographic emulation versus standard assessment for detection of coronary stenoses.

The present study investigated angiographic emulation of multislice computed tomography (MSCT) (catheter-like visualization) as an alternative approach of analyzing and visualizing findings in comparison with standard assessment. Thirty patients (120 coronary arteries) were randomly selected from 90 prospectively investigated patients with suspected coronary artery disease who underwent MSCT (16-slice scanner, 0.5 mm collimation, 400 ms rotation time) prior to conventional coronary angiography for comparison of both approaches. Sensitivity and specificity of angiographic emulation [81% (26/32) and 93% (82/88)] were not significantly different from those of standard assessment [88% (28/32) and 99% (87/88)], while the per-case analysis time was significantly shorter for angiographic emulation than for standard assessment (3.4 +/- 1.5 vs 7.0 +/- 2.5 min, P < 0.001). Both interventional and referring cardiologists preferred angiographic emulation over standard curved multiplanar reformations of MSCT coronary angiography for illustration, mainly because of improved overall lucidity and depiction of sidebranches (P < 0.001). In conclusion, angiographic emulation of MSCT reduces analysis time, yields a diagnostic accuracy comparable to that of standard assessment, and is preferred by cardiologists for visualization of results.

Aged↗
PubMed2007

Coronary artery stenosis quantification using multislice computed tomography.

RATIONALE AND OBJECTIVES: Reliable noninvasive detection of stenoses with multislice computed tomography (MSCT) is feasible. This study's aim was to analyze the agreement, correlation, and reliability of MSCT with conventional coronary angiography as the reference standard for quantification of coronary artery stenoses. MATERIALS AND METHODS: A total of 118 significant (at least 50%) coronary artery stenoses with a reference vessel diameter of at least 1.5 mm in 62 patients were analyzed by MSCT using 16 detector rows (Aquilion, Toshiba, Otawara, Japan), multisegment reconstruction, and voxel sizes of 0.35x0.35x0.5 mm. The degree of stenosis on MSCT and quantitative coronary angiography (QCA) was measured by correlating the difference between the reference vessel diameter (average of 2 measurements directly proximal and distal to the stenosis) and the stenotic vessel diameter to the reference vessel diameter. RESULTS: Correlation between the percent diameter stenosis determined by MSCT (78.2+/-13.6%) and QCA (76.0+/-14.8%) was significant (P<0.001) but only moderately so (R=0.51). Bland-Altman analysis revealed no systematic under- or overestimation with MSCT but large limits of agreements (+/-27.6%). Also the limits of agreement for interobserver agreement (reliability) of MSCT data were considerably large (+/-24.8%). Among the 27 coronary artery stenoses with a reference diameter of at least 3.5 mm, there was improved correlation (R=0.80) and the limits of agreement between MSCT and QCA were significantly smaller (+/-17.3%, P<0.008). The agreement between MSCT and QCA was not significantly different for stenoses with no calcification or only calcium spots (+/-28.2%) as compared with those with moderate-or-severe calcifications (+/-27.3%; P=0.8). MSCT allowed correct classification of coronary stenoses into low-grade (below 75%) and high-grade stenoses (at least 75%), in 62% (73 of 118). CONCLUSIONS: The accuracy and reliability of coronary artery stenosis quantification with MSCT using isotropic voxel sizes and multisegment reconstruction is still too low to recommend routine clinical application because of rather low agreement, correlation, and reliability. Despite these limitations, the current results demonstrate the potential of MSCT for reliable and accurate quantification of coronary artery stenoses in the near future provided that further improvements in spatial and temporal resolution will be achieved.

Anatomy, Cross-Sectional↗
PubMed2006

Evaluation of global and regional left ventricular function with 16-slice computed tomography, biplane cineventriculography, and two-dimensional transthoracic echocardiography: comparison with magnetic resonance imaging.

OBJECTIVES: We sought to compare left ventricular (LV) function assessed with multislice computed tomography (MSCT), biplane cineventriculography (CVG), and transthoracic echocardiography (Echo), with magnetic resonance imaging (MRI) as the reference standard. BACKGROUND: With the same data as acquired for noninvasive coronary angiography, MSCT enables registration of myocardial function. METHODS: A total of 88 patients (64 men and 24 women) underwent MSCT with 16 x 0.5 mm detector collimation, CVG, and MRI, whereas Echo was retrospectively analyzed in a subset of 30 patients. RESULTS: Regarding the ejection fraction, the agreement was significantly superior for MSCT than for CVG (+/- 10.2% vs. +/- 16.8%; p < 0.001) and Echo (+/- 11.0% vs. +/- 21.2%; p < 0.001). For the end-diastolic and end-systolic volumes, the limits of agreement with CVG (p < 0.001) and Echo (p < 0.001 and p < 0.02, respectively) were also significantly larger than with MSCT. In comparison with MSCT, CVG significantly overestimated the end-diastolic and end-systolic volumes (p < 0.001). Intraobserver analysis of MSCT yielded limits of agreement for ejection fraction (+/- 4.8%), end-diastolic volume (+/- 15.6 ml) and end-systolic volume (+/- 8.0 ml), and myocardial mass (+/- 18.2 g). The accuracy in identifying patients and myocardial segments with abnormal regional function was significantly higher with MSCT (84% and 95%) than with CVG (63% and 90%; p < 0.002 and p < 0.001), whereas MSCT and Echo were not significantly different in identifying patients with abnormal regional function. CONCLUSIONS: Our results indicate that the assessment of global and regional LV function with MSCT is more accurate than with CVG, whereas MSCT is superior to Echo for global function. This suggests that MSCT allows reliable evaluation of global and regional LV function.

Aged↗
PubMed2006

Cost effectiveness of coronary angiography and calcium scoring using CT and stress MRI for diagnosis of coronary artery disease.

We compared the cost effectiveness of recent approaches [coronary angiography and calcium scoring using computed tomography (CT) and stress magnetic resonance imaging (MRI)] to the diagnosis of coronary artery disease (CAD) with those of the traditional diagnostic modalities [conventional angiography (CATH), exercise ECG, and stress echocardiography] using a decision tree model. For patients with a 10% to 50% pretest likelihood of coronary artery disease, non-invasive coronary angiography using CT was the most cost effective approach, with costs per correctly identified CAD patient of euro4,435 (10% likelihood) to euro1,469 (50% likelihood). Only for a pretest likelihood of 30% to 40% was calcium scoring using CT more cost effective than any of the traditional diagnostic modalities, while MRI was not cost effective for any pretest likelihood. At a pretest likelihood of 60%, CT coronary angiography and CATH were equally effective, while CATH was most cost effective for a pretest likelihood of at least 70%. In conclusion, up to a pretest likelihood for coronary artery disease of 50%, CT coronary angiography is the most cost-effective procedure, being superior to the other new modalities and the most commonly used traditional diagnostic modalities. With a very high likelihood for disease (above 60%), CATH is the most effective procedure from the perspective of society.

Adult↗
PubMed2006

Noninvasive detection of coronary artery stenoses with multislice computed tomography or magnetic resonance imaging.

BACKGROUND: Multislice computed tomography (CT) and magnetic resonance imaging (MRI) are the main candidates for noninvasive coronary angiography; however, multislice CT, unlike MRI, exposes patients to radiation and an iodinated intravenous contrast agent. OBJECTIVE: To compare the diagnostic accuracy of multislice CT and MRI for noninvasive detection of clinically significant coronary stenoses (> or =50%). DESIGN: Prospective intention-to-diagnose study. SETTING: Single tertiary referral center, Berlin, Germany. PATIENTS: 129 consecutive patients with suspected coronary artery disease. INTERVENTIONS: Multislice CT and MRI were both performed within a median of 1 day before conventional coronary angiography, which served as the reference standard. MEASUREMENTS: Diagnostic performance of multislice CT and MRI. RESULTS: 129 patients completed the study. Altogether, 108 patients with 430 vessels could be examined with both multislice CT and MRI and were used for analysis. In the per-patient analysis, the sensitivity of multislice CT (92% [95% CI, 82% to 96%]) was significantly higher than that of MRI (74% [CI, 61% to 83%]; P = 0.013). The sensitivity for detecting clinically significant stenoses was 82% for multislice CT and 54% for MRI (P < 0.001). Specificity and negative predictive value of multislice CT and MRI in the per-vessel analysis were 90% versus 87% (P = 0.73) and 95% versus 90% (P = 0.032), respectively. The effective radiation dose used with multislice CT (mean, 12.3 mSv [SD, 1.4]) in a consecutive subgroup of 73 patients was not significantly different from that used with diagnostic cardiac catheterization (11.4 mSv [SD, 4.8]) (P = 0.169). Most patients (74%) indicated that they would prefer multislice CT for future diagnostic imaging (P < 0.001). LIMITATIONS: This was a single-center study with 129 patients. CONCLUSIONS: In patients referred for conventional coronary angiography, multislice CT compares favorably with MRI for noninvasive detection of coronary stenoses.

Coronary Angiography↗
PubMed2006

Head-to-head comparison of multislice computed tomography and exercise electrocardiography for diagnosis of coronary artery disease.

AIMS: To prospectively compare multislice computed tomography (MSCT) and exercise electrocardiography (ex-ECG) for diagnosis of coronary artery disease (CAD) with conventional coronary angiography as the reference standard. METHODS AND RESULTS: A consecutive cohort of 80 patients with suspected CAD was examined with MSCT using 16 x 0.5 mm detector collimation, ex-ECG, and conventional coronary angiography according to standard protocols. Results were compared using the paired McNemar's test, the chi(2) test, and 95%CIs. Both the sensitivity and specificity of MSCT [91% (40 of 44 patients, 95%CI 78-97%) and 83% (30 of 36 patients, 95%CI 67-94%)] were significantly higher (P = 0.039 and P < 0.001) than those for ex-ECG [73% (32 of 44 patients, 95%CI 57-85%) and 31% (11 of 36 patients, 95%CI 16-48%)]. The pairwise McNemar's test showed significant differences between MSCT and ex-ECG in the overall diagnosis in patients with suspected CAD (P = 0.036). The rate of non-diagnostic examinations was not significantly (P = 0.078) different between MSCT and ex-ECG [8% (6 of 80 patients, 95%CI 3-16%) vs. 19% (15 of 80 patients, 95%CI 11-29%)]. CONCLUSION: In this consecutive cohort of patients scheduled to undergo conventional coronary angiography, the performance of MSCT for diagnosis of CAD was superior to that of ex-ECG.

Aged↗
PubMed2006

Myocardial viability: assessment with three-dimensional MR imaging in pigs and patients.

PURPOSE: To prospectively evaluate the correlation between a three-dimensional (3D) delayed enhancement magnetic resonance (MR) imaging sequence and a two-dimensional (2D) delayed enhancement MR imaging sequence for noninvasive assessment of myocardial viability in pigs and patients. MATERIALS AND METHODS: The pig and patient studies were approved by the responsible authorities, and patients gave written informed consent. MR imaging was performed by using a rapid 3D inversion-recovery balanced steady-state free precession sequence and a 2D segmented inversion-recovery fast low-angle shot sequence as the reference standard. Fourteen pigs with reperfused (n=7) or nonreperfused (n=7) myocardial infarction and 17 patients (13 men, four women; mean age, 64.9 years+/-8.6 [standard deviation]) suspected of having myocardial infarction were included. Linear regression analysis and Bland-Altman analysis were used to compare the infarction volumes. RESULTS: In 10 of the 14 pigs the induction of myocardial infarction was successful. In these pigs, altogether 81 segments with myocardial infarction were demonstrated by both MR sequences, and agreement between the two sequences for classification of transmural extent of myocardial infarction was 99.7%. The infarction volume determined by using 3D MR imaging (4.64 cm3+/-2.48) in the pigs highly correlated with that of 2D MR imaging (4.65 cm3+/-2.39, r=0.989, P<.001) and that of staining by using triphenyltetrazolium chloride (4.67 cm3+/-2.44, r=0.996, P<.001). Thirteen of the 17 patients examined showed myocardial infarction in 34 myocardial segments with both sequences, and agreement between the two sequences for classification of transmural extent of myocardial infarction was 98.6%. In the patients, the infarction volume determined with both sequences highly correlated (9.71 cm3+/-7.47 for the 3D sequence vs 10.01 cm3+/-8.04 for the 2D sequence, r=0.982, P<.001). The breath-hold time necessary for the 3D MR imaging (21.0+/-2.3 seconds) was significantly shorter than that for 2D MR imaging (188.3+/-20.2 seconds, P<.001). CONCLUSION: Myocardial infarction volumes obtained with the 3D MR imaging sequence are highly correlated and in good agreement with volumes obtained with the 2D MR imaging standard approach and reduced the acquisition time by a factor of nine.

Animals↗
PubMed2006

Combination of free-breathing and breathhold steady-state free precession magnetic resonance angiography for detection of coronary artery stenoses.

PURPOSE: To analyze the incremental diagnostic value of a combination of two approaches (free-breathing and breathhold) vs. the sole free-breathing approach to coronary magnetic resonance angiography (CMRA) for detection of significant stenoses. MATERIALS AND METHODS: Thirty patients were consecutively included in this prospective trial. CMRA was performed on a 1.5-T MR scanner (Magnetom Sonata, Siemens) using a balanced steady-state free precession (SSFP) sequence during free-breathing (2.4 x 0.9 x 0.7 mm3). Breathholding acquisitions (3.0 x 1.5 x 0.7 mm3) were only performed in cases in which the quality of free-breathing CMRA precluded assessment. Patients with contraindications to CMRA, claustrophobia, or nonassessable images were not excluded from the assessment of diagnostic accuracy (intention-to-diagnose design). RESULTS: In 60% of all free-breathing coronary acquisitions the image quality was adequate for diagnostic assessment. For the remaining 40% of the cases, breathhold acquisitions were obtained. The sensitivity, specificity, nonassessable rate, and accuracy in identifying main coronary branches with significant stenoses using the combination of both breathing approaches and the free-breathing approach alone were 65% vs. 32%, 73% vs. 53%, 24% vs. 52%, and 71% vs. 46%, respectively (P < 0.001). CONCLUSION: In this consecutive cohort of patients, the combination of free-breathing and breathhold CMRA significantly improved diagnostic accuracy. Nevertheless, even this combination did not reach accuracies sufficient for routine clinical application.

Cohort Studies↗
PubMed2006

Respiratory-triggered MRCP applying parallel acquisition techniques.

PURPOSE: To evaluate the influence of parallel imaging on the image quality of respiratory triggered magnetic resonance cholangiopancreatography (MRCP). MATERIALS AND METHODS: A total of 30 consecutive patients underwent MRCP applying a respiratory triggered T2-weighted (T2w) turbo spin-echo (TSE) sequence without and with parallel imaging (acceleration factor of 2). Acquisition times of both sequences were recorded. Quantitative evaluation included measurement of a contour sharpness index of two segments of the pancreaticobiliary tree as well as calculation of the relative contrast between ductal structures and organ parenchyma at four different segments. The qualitative evaluation was performed by two independent radiologists who graded overall image quality, depiction of eight segments of the pancreaticobiliary tree, and the frequency of artifacts. RESULTS: The application of parallel imaging significantly (P<0.05) reduced the acquisition time of the respiratory triggered MRCP sequence by 37.7% (six minutes and two seconds+/-one minute and 26 seconds vs. three minutes and 46 seconds+/-58 seconds). The quantitative and qualitative evaluation revealed no statistically significant differences between the two sequences (P>0.05). The frequency of artifacts was at the same level for both sequences as well. CONCLUSION: The application of parallel imaging for respiratory triggered MRCP significantly reduces the acquisition time without relevant influence on image quality.

Adult↗
PubMed2006

Multisegment and halfscan reconstruction of 16-slice computed tomography for assessment of regional and global left ventricular myocardial function.

RATIONALE AND OBJECTIVES: We sought to prospectively compare multisegment and halfscan reconstruction of 16-slice computed tomography (CT) for the assessment of regional and global left ventricular myocardial function with magnetic resonance imaging (MRI) as the reference standard. MATERIALS AND METHODS: Forty-two patients underwent CT with 16 x 0.5-mm detector collimation. Electrocardiogram-gated reconstructions were generated with multisegment reconstruction (using up to 4 segments correlated with the raw data of up to 4 heartbeats) and standard halfscan reconstruction. Steady-state free-precession cine MRI was acquired within 24 hours. RESULTS: More normal myocardial segments were identified correctly with multisegment (95%, 620/656) compared with halfscan reconstruction (88%, 582/656) of CT (P < 0.001). Also, the accuracy (92% [657/714] vs. 87% [620/714]) and rate of nondiagnostic segments (0% vs. 5% [33/714]) were significantly better when using multisegment reconstruction (P < 0.001). The image quality with multisegment reconstruction was significantly superior to that achieved with halfscan reconstruction (P < 0.001). In the assessment of global left ventricular function, multisegment and halfscan reconstruction of CT showed high correlations for all parameters with MRI, whereas Bland-Altman analysis revealed smaller limits of agreement for assessment of myocardial mass with multisegment reconstruction (P = 0.025), but no significant differences between both reconstruction techniques in the measurement of left ventricular volumes as compared with MRI. CONCLUSIONS: Multisegment reconstruction of 16-detector row CT improves image quality and assessment of regional wall motion compared with standard halfscan reconstruction.

Adult↗
PubMed2006

Ernst Ferdinand Sauerbruch and his ambiguous role in the period of National Socialism.

The role of German physicians under National Socialism is highly controversial. We show that Ferdinand Sauerbruch, one of twentieth century's most outstanding surgeons and chair of surgery at Berlin's Charité from 1927 to 1949, openly supported National Socialism in his public statements and in his position as head of the medical section of the Reich Research Council. He was appointed state councilor and received the Knight's Cross of the War Merit Cross by the National Socialists. But Sauerbruch also supported victims of Nazi persecution, attempted to use his influence to put a stop to the "Euthanasia Program T4," and in private expressed his criticism of National Socialists. The ambiguous stance of Ferdinand Sauerbruch is probably more typical of the role physicians played during National Socialism than the well-known black-and-white cases.

General Surgery↗
PubMed2005

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.

Contrast Media↗