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Biomedical subjects

David Maintz

Publications and source records attributed to David Maintz.

At least 19 recordsLinked to original sources
PubMed2006

Granulocyte-colony stimulating factor (G-CSF) and G-CSF receptor expression in human ischemic stroke.

Granulocyte-colony stimulating factor (G-CSF) receptor signaling counteracts detrimental pathways in ischemic stroke. In rodents, neuroprotection provided by the G-CSF system involves up-regulation of the G-CSF receptor and its ligand, G-CSF, during cerebral ischemia. The confirmation of a similar response in the human brain would be an important rationale for the use of G-CSF in clinical stroke trials. Therefore, the temporal and cellular profile of G-CSF and G-CSF receptor expression was examined in a series of human stroke brains. The median age of the 21 stroke patients was 67 years; median time from death to autopsy was 24 h (range: 10-67 h). In acute ischemic stroke, strong neuronal G-CSF receptor immunoreactivity was encountered in the infarct area and the peri-infarct rim as compared to the contralateral cortex. In subacute infarctions, microglial and macrophage G-CSF receptor immunoreactivity predominated, whereas chronic infarction was characterized by the presence of G-CSF receptor expressing reactive astrocytes. Neuronal G-CSF expression was encountered very early upon ischemic stroke. At later time-points, an up-regulation of vascular G-CSF expression in the peri-infarct area prevailed. In conclusion, the observed up-regulation of G-CSF receptors and G-CSF points towards a role in the pathophysiology of human ischemic stroke.

Aged↗
PubMed2006

Assessment of regional left ventricular function with multidetector-row computed tomography versus magnetic resonance imaging.

This study compares quantitative and qualitative information on global and regional left ventricular (LV) function obtained with multidetector-row computed tomography (MDCT) with that obtained with magnetic resonance imaging (MRI) in patients with a high prevalence of LV wall motion abnormalities. Thirty patients (19 male, 63.7+/-15.1 years) with myocardial infarction (n=12), coronary artery disease (n=9), arrhythmogenic right ventricular cardiomyopathy (n=6), and dilation cardiomyopathy (n=3) were included. Segmental LV wall motion (LV-WM) was assessed using a 4-point scale. Wall thickness measurements were calculated in diastolic and systolic short axis images. Two hundred and fifty-two out of 266 (94.7%) normal and 189 out of 214 (88.3%) segments with decreased wall motion were correctly identified by MDCT, yielding a sensitivity of 88% and specificity of 95% for identification of wall motion abnormalities. LV-WM scores were identical in 86.7% of 480 segments (kappa=0.809). MDCT had a tendency to underestimate the degree of wall motion impairment. Interobserver agreement was lower in MDCT (66.5%) than in MRI (89.1%; p<0.01). Normokinetic segments are reliably identified with MDCT. Sensitivity for detection and accurate classification of LV wall motion abnormalities need to be improved. Better temporal resolution of the CT system seems to be the most important factor for enhancing MDCT performance.

Adrenergic beta-Antagonists↗
PubMed2006

Selective coronary artery plaque visualization and differentiation by contrast-enhanced inversion prepared MRI.

AIMS: We sought to evaluate the utility of contrast-enhanced coronary magnetic resonance imaging (CE-MRI) for selective visualization and non-invasive differentiation of atherosclerotic coronary plaque in humans. METHODS AND RESULTS: Nine patients with coronary artery disease (CAD) as confirmed by X-ray angiography and multidetector computed tomography (MDCT) were studied by T1-weighted black blood inversion recovery coronary MRI before (N-IR) and after administration of Gd-DTPA (CE-IR). Plaques were categorized as calcified, non-calcified, and mixed based on their Hounsfield number derived from MDCT. With MDCT, a total of 29 plaques were identified, including calcified (n=6), non-calcified (n=6), and mixed calcified/non-calcified (n=17). On N-IR MRI, 26 plaques (90%) were dark, whereas three plaques (two non-calcified and one mixed) appeared bright. On CE-MRI, 13/29 (45%) plaques, 11 of which were mixed, one non-calcified, and one calcified showed contrast uptake. All others remained dark. CONCLUSION: In this preliminary study, we demonstrate the potential utility of CE-IR MRI for selective plaque visualization and differentiation of plaque types. The observed contrast uptake may be associated with endothelial dysfunction, neovascularization, inflammation, and/or fibrosis.

Adult↗
PubMed2006

64- Versus 16-slice CT angiography for coronary artery stent assessment: in vitro experience.

OBJECTIVES: We sought to assess the visualization of different coronary artery stents and the delineation of in-stent stenoses using 64- and 16-slice multidector computed tomography (MDCT). MATERIALS AND METHODS: A total of 15 different coronary stents with a simulated in-stent stenosis were placed in a vascular phantom and scanned with a 16-slice and a 64-slice MDCT at orientations of 0 degree, 45 degrees, and 90 degrees relative to the scanner's z-axis. Visible lumen diameter and attenuation in the stented and the unstented segment of the phantom were measured. Three readers assessed stenosis delineation and visualization of the residual lumen using a 5-point scale. RESULTS: Artificial lumen narrowing (ALN) was significantly reduced with 64-slice CT compared with 16-slice CT. At an angle of 0 degree, 45 degrees, and 90 degrees relative to the scanner's z-axis, the ALN for 16-slice CT was 42.2%, 39.8%, and 44.0% using a slice-thickness of 1.0 mm and 40.9%, 40.4%, and 41.6% using a slice thickness of 0.75 mm, respectively. With 64-slice CT, the ALN was 39.1%, 37.3%, and 36.0% at the respective angles. The differences between attenuation values in the stented and unstented segment of the tube were significantly lower for 64-slice CT. Mean visibility scores were significantly higher for 64-slice CT. CONCLUSION: Use of the 64-slice CT results in superior visualization of the stent lumen and in-stent stenosis compared with 16-slice CT, especially when the stent is orientated parallel to the x-ray beam.

Coronary Angiography↗
PubMed2006

Electrocardiogram-independent image reconstruction in cardiac multidetector computed tomography using retrospective motion synchronization.

OBJECTIVE: We sought to evaluate an electrocardiogram (ECG)-independent image reconstruction technique for coronary computed tomography (CT)-angiography based on cardiac motion. MATERIALS AND METHODS: The raw data from 20 patients was reconstructed with both an ECG-gated algorithm and a motion-dependent algorithm that calculates the cardiac motion-function directly from the CT raw data using a center of mass technique. Images were reconstructed in 5% steps over the R-R interval and the cardiac motion-cycle. For both approaches multiplanar reformations were created and the set of images with the least motion artifacts was used for the evaluation. Motion artifacts affecting the ascending aorta, the left main coronary artery and the entire course of the LAD, LCX and RCA were scored using a 5-point scale. RESULTS: The mean optimal reconstruction window was at 60% of the R-R interval and 30% of the cardiac motion cycle. A total of 73 of 100 vascular regions showed no motion artifacts in ECG-gated images, with the motion-synchronized algorithm only 41 regions were free of motion artifacts. The mean motion-score was 1.4 (+/-0.6) and 2.4 (+/-1.2) respectively (P < 0.05). CONCLUSION: In the currently implemented form the motion-gated algorithm is inferior to ECG-gated image reconstruction but can be used in patients with an incomplete or corrupt ECG-signal.

Algorithms↗
PubMed2006

MDCT determination of volume and function of the left ventricle: are short-axis image reformations necessary?

OBJECTIVE: Determination of left ventricular (LV) volumes and global function parameters from MDCT data sets is usually based on short-axis reformations from primarily reconstructed axial images, which prolong postprocessing time. The aim of this study was to evaluate the feasibility of LV volumetry and global LV function assessment from axial images in comparison with short-axis image reformations. SUBJECTS AND METHODS: This study consisted of 20 patients with either coronary artery disease or dilated cardiomyopathy. We evaluated MDCT results using cine MRI as the reference technique. RESULTS: LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) were significantly overestimated by the axial MDCT approach in comparison with volume measurements from short-axis CT image reformations. The mean LV ejection fraction (LVEF) was not significantly different (41.2% vs 42.7%). Short-axis and axial MDCT determination of LVEF revealed a systematic underestimation by a mean +/- SD of -2.1% +/- 3.6% versus -3.6% +/- 8.2%, respectively, when compared with LVEF values based on cine MRI. The interobserver variability for volume and function measurements from axial images (LVEDV = 8.5%, LVESV = 10.8%, LVEF = 9.6%) was slightly higher than those measurements from short-axis reformations (LVEDV = 7.2%, LVESV = 9.5%, LVEF = 8.7%). The mean total evaluation time was significantly shorter using axial images (14.1 +/- 3.9 min) compared with short-axis reformations (16.9 +/- 5.2 min) (p < 0.05). CONCLUSION: Determination of LV volumes and assessment of global LV function from axial MDCT image reformations is feasible and time efficient. This approach might be a clinically useful alternative to established short-axis-based measurements in patients with normal or near-normal LV function. A progressive underestimation of LVEF with increasing LV volumes may limit the clinical applicability of the axial approach in patients with dilated cardiomyopathy.

Cardiomyopathy, Dilated↗
PubMed2006

Frequency of unexpected and important histopathological findings in routine intervertebral disc surgery.

OBJECT: The value of routine histopathological examination of intervertebral disc tissue has been questioned, but sufficient numbers of studies have yet to be conducted to provide a definitive sense of its importance. The aim of this study was to investigate the nature and frequency of unexpected histopathological findings in intervertebral disc surgery. METHODS: The authors conducted a retrospective examination of consecutive surgical specimens obtained in patients with benign indication for discectomy at four neurosurgical centers. Surgical specimens obtained during 2102 operations (2177 intervertebral discs) in 2017 patients were evaluated. In addition to one case of cavernous malformation, two specimens (obtained in 0.1% of patients) revealed unexpected pathological diagnoses of malignancy (metastasized prostate carcinoma and diffuse large B-cell lymphoma). CONCLUSIONS: The results of this retrospective study suggest that routine histopathological examination of specimens obtained during intervertebral disc procedures is both justified and cost effective.

Adult↗
PubMed2005

64-slice multidetector coronary CT angiography: in vitro evaluation of 68 different stents.

The purpose of this study was to test a large sample of different coronary artery stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation, and image noise in 64-slice multidetector-row computed tomography (MDCT) in vitro and to provide a catalogue of currently used coronary artery stents when imaged with state-of the-art MDCT. We examined 68 different coronary artery stents (57 stainless steel, four cobalt-chromium, one cobalt-alloy, two nitinol, four tantalum) in a coronary artery phantom (vessel diameter 3 mm, intravascular attenuation 250 HU, extravascular density -70). Stents were imaged in axial orientation with standard parameters: 32 x 0.6 collimation, pitch 0.24, 680 mAs, 120 kV, rotation time 0.37 s. Four different image reconstructions were obtained with varying convolution kernels and section thicknesses: (1) soft, 0.6 mm, (2) soft, 0.75, (3) medium soft, 0.6, and (4) stent-optimized sharp, 0.6. To evaluate visualization characteristics of of the stent, the lumen diameter, intraluminal density and noise were measured. The high-resolution kernel offered significantly better average lumen visualization (57% +/-10%) and more realistic lumen attenuation (222 HU +/-66 HU) at the expense of increased noise (15.3 HU +/-3.7 HU) compared with the soft and medium-soft CT angiography (CTA) protocol (p<0.001 for all). Stents with a lumen visibility of more than 66% were: Arthos pico, Driver, Flex, Nexus2, S7, Tenax complete, Vision (all 67%), Symbiot, Teneo (70%), and Radius (73%). Only ten stents showed a lumen visibility of less than 50%. Stent lumen visibility largely varies depending on the stent type. Even with the improved spatial resolution of 64-slice CT, a stent-optimized kernel remains beneficial for stent visualization when compared with the standard medium-soft CTA protocol. Using 64-slice CT and high-resolution kernel, the majority of stent products show a lumen visibility of more than 50% of the stent diameter.

Alloys↗
PubMed2005

Assessment of coronary artery stents using 16-slice MDCT angiography: evaluation of a dedicated reconstruction kernel and a noise reduction filter.

To compare the effect of different reconstruction kernels and a noise-reducing postprocessing filter on the delineation of coronary artery stents in 16-slice CT-angiography. Ten patients with coronary stents (seven LAD, five RCX and three RCA) were examined with a 16-slice MDCT using standard acquisition parameters. Images were reconstructed using a medium soft (B30f) and a dedicated, edge-enhancing kernel (B46f). Additional postprocessing with an edge-preserving filter was performed on B46f images to reduce the image noise. In multiplanar reformations (MPRs) along and perpendicular to the stent axis, intraluminal attenuation values and the visible lumen diameter were measured. Image noise was measured in the subcutaneous fat using a region of interest (ROI) technique. Arterial enhancement in the aorta was 275.1 HU. Attenuation in the stent lumen was 390.4, 340.0 and 346.8 HU in MPRs derived from B30f, original B46 and postprocessed B46f images. The mean noise level was 20.4, 35.0 and 24.9 HU respectively. The visible lumen diameter was significantly greater in B46f and postprocessed B46f images (2.17 and 2.16 mm), compared to 1.93 mm in B30f images (p<0.01). Edge-enhancing reconstruction kernels increase the visible stent lumen, but also increase image noise. Dedicated postprocessing filters can reduce the introduced noise without a loss of spatial resolution.

Artifacts↗
PubMed2005

3.0 T vs. 1.5 T MR angiography: in vitro comparison of intravascular stent artifacts.

PURPOSE: To evaluate the signal characteristics of different iliac artery stents in MR angiography (MRA) at 3 T in comparison with 1.5 T. MATERIALS AND METHODS: Sixteen iliac artery stents were implanted in plastic tubes filled with a solution of Gd-DTPA and imaged at 3 T and 1.5 T using a T1-weighted 3D spoiled gradient-echo sequence. Image analysis included a subjective assessment of artifact characteristics, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements in stented and unstented vessel parts, and quantitative measurements of total artifact size. RESULTS: The pattern of stent artifacts inside the stents evidently did not differ at 3 T and 1.5 T. The average total size of the artifact areas surrounding the stents was significantly larger at 3 T (P < 0.03). However, within the stented part of the vessel phantom, the signal of the lumen and its contrast to modeled surrounding tissue was significantly higher at the higher field. The mean SNR of the lumen increased from 95.5 at 1.5 T to 127.3 at 3 T, and the CNR of the vessel increased from 70.3 to 93. CONCLUSION: Assessment of the stent lumen in iliac artery stents in a phantom model is not compromised by imaging at 3 T compared to 1.5 T. The signal gain inside the stented part of the vessel lumen at higher field compensates for the higher degree of stent artifacts seen in stents made of steel or cobalt.

Artifacts↗
PubMed2005

Comparison of 3D segmented gradient-echo and steady-state free precession coronary MRI sequences in patients with coronary artery disease.

OBJECTIVE: Our objective was to compare two state-of-the-art coronary MRI (CMRI) sequences with regard to image quality and diagnostic accuracy for the detection of coronary artery disease (CAD). SUBJECTS AND METHODS: Twenty patients with known CAD were examined with a navigator-gated and corrected free-breathing 3D segmented gradient-echo (turbo field-echo) CMRI sequence and a steady-state free precession sequence (balanced turbo field-echo). CMRI was performed in a transverse plane for the left coronary artery and a double-oblique plane for the right coronary artery system. Subjective image quality (1- to 4-point scale, with 1 indicating excellent quality) and objective image quality parameters were independently determined for both sequences. Sensitivity, specificity, and accuracy for the detection of significant (> or = 50% diameter) coronary artery stenoses were determined as defined in invasive catheter X-ray coronary angiography. RESULTS: Subjective image quality was superior for the balanced turbo field-echo approach (1.8 +/- 0.9 vs 2.3 +/- 1.0 for turbo field-echo; p < 0.001). Vessel sharpness, signal-to-noise ratio, and contrast-to-noise ratio were all superior for the balanced turbo field-echo approach (p < 0.01 for signal-to-noise ratio and contrast-to-noise ratio). Of the 103 segments, 18% of turbo field-echo segments and 9% of balanced turbo field-echo segments had to be excluded from disease evaluation because of insufficient image quality. Sensitivity, specificity, and accuracy for the detection of significant coronary artery stenoses in the evaluated segments were 92%, 67%, 85%, respectively, for turbo field-echo and 82%, 82%, 81%, respectively, for balanced turbo field-echo. CONCLUSION: Balanced turbo field-echo offers improved image quality with significantly fewer nondiagnostic segments when compared with turbo field-echo. For the detection of CAD, both sequences showed comparable accuracy for the visualized segments.

Aged↗
PubMed2004

Multi-detector row computed tomography of the heart: does a multi-segment reconstruction algorithm improve left ventricular volume measurements?

A multi-segment cardiac image reconstruction algorithm in multi-detector row computed tomography (MDCT) was evaluated regarding temporal resolution and determination of left ventricular (LV) volumes and global LV function. MDCT and cine magnetic resonance (CMR) imaging were performed in 12 patients with known or suspected coronary artery disease. Patients gave informed written consent for the MDCT and the CMR exam. MDCT data were reconstructed using the standard adaptive cardiac volume (ACV) algorithm as well as a multi-segment algorithm utilizing data from three, five and seven rotations. LV end-diastolic (LV-EDV) and end-systolic volumes and ejection fraction (LV-EF) were determined from short-axis image reformations and compared to CMR data. Mean temporal resolution achieved was 192+/-24 ms using the ACV algorithm and improved significantly utilizing the three, five and seven data segments to 139+/-12, 113+/-13 and 96+/-11 ms (P<0.001 for each). Mean LV-EDV was without significant differences using the ACV algorithm, the multi-segment approach and CMR imaging. Despite improved temporal resolution with multi-segment image reconstruction, end-systolic volumes were less accurately measured (mean differences 3.9+/-11.8 ml to 8.1+/-13.9 ml), resulting in a consistent underestimation of LV-EF by 2.3-5.4% in comparison to CMR imaging (Bland-Altman analysis). Multi-segment image reconstruction improves temporal resolution compared to the standard ACV algorithm, but this does not result in a benefit for determination of LV volume and function.

Adult↗
PubMed2004

3.0 Tesla magnetic resonance angiography of endovascular aortic stent grafts: phantom measurements in comparison with 1.5 Tesla.

RATIONALE AND OBJECTIVES: This study evaluated different stent grafts by 3 T magnetic resonance angiography (MRA) with respect to lumen visibility, susceptibility-induced signal loss, and type of stent artifacts compared with 1.5 T MRA in a phantom model. METHODS: Six different stent-grafts (tube: n = 3, bifurcated: n = 3) were evaluated by 3 T and 1.5 T MRA using a tube phantom. MRA was performed using T1-weighted sequences at both systems with comparable parameters (3T: TR 5.4/TE 2.0/FA 30 degrees, 1.5 T: TR 6.2/TE 2.2/FA 30 degrees). A blind study of the image quality, including artifacts, was performed by 3 radiologists. Furthermore, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) values were calculated. Statistical analysis was performed with Student's t test (P < 0.05). RESULTS: One Elgiloy stent graft showed almost a complete intraluminal signal loss at 1.5 and 3 T. All other models could be evaluated by both systems by MRA, resulting in a favorable lumen visibility (score: 1) for prostheses made of nitinol. Scores for overall image quality and artifacts were the same for both MR systems. SNR and CNR values of the stented part of the vessel phantom increased from 320 +/- 33 to 618 +/- 40 and from 306 +/- 34 to 596 +/- 40 at 3 T when compared with 1.5 T, resulting in a significant signal gain of 93% at the higher field strength. CONCLUSIONS: 3 Tesla MRA of aortic stent grafts in a phantom model demonstrates an increase in SNR and CNR when compared with 1.5 T. However, the magnitude of imaging artifacts as well as coherent intraluminal signal loss within the stent does not increase equally in both MR systems.

Aorta↗
PubMed2004

Coronary MR angiography: comparison of quantitative and qualitative data from four techniques.

OBJECTIVE: The optimal coronary MR angiography sequence has yet to be determined. We sought to quantitatively and qualitatively compare four coronary MR angiography sequences. SUBJECTS AND METHODS. Free-breathing coronary MR angiography was performed in 12 patients using four imaging sequences (turbo field-echo, fast spin-echo, balanced fast field-echo, and spiral turbo field-echo). Quantitative comparisons, including signal-to-noise ratio, contrast-to-noise ratio, vessel diameter, and vessel sharpness, were performed using a semiautomated analysis tool. Accuracy for detection of hemodynamically significant disease (> 50%) was assessed in comparison with radiographic coronary angiography. RESULTS: Signal-to-noise and contrast-to-noise ratios were markedly increased using the spiral (25.7 +/- 5.7 and 15.2 +/- 3.9) and balanced fast field-echo (23.5 +/- 11.7 and 14.4 +/- 8.1) sequences compared with the turbo field-echo (12.5 +/- 2.7 and 8.3 +/- 2.6) sequence (p < 0.05). Vessel diameter was smaller with the spiral sequence (2.6 +/- 0.5 mm) than with the other techniques (turbo field-echo, 3.0 +/- 0.5 mm, p = 0.6; balanced fast field-echo, 3.1 +/- 0.5 mm, p < 0.01; fast spin-echo, 3.1 +/- 0.5 mm, p < 0.01). Vessel sharpness was highest with the balanced fast field-echo sequence (61.6% +/- 8.5% compared with turbo field-echo, 44.0% +/- 6.6%; spiral, 44.7% +/- 6.5%; fast spin-echo, 18.4% +/- 6.7%; p < 0.001). The overall accuracies of the sequences were similar (range, 74% for turbo field-echo, 79% for spiral). Scanning time for the fast spin-echo sequences was longest (10.5 +/- 0.6 min), and for the spiral acquisitions was shortest (5.2 +/- 0.3 min). CONCLUSION: Advantages in signal-to-noise and contrast-to-noise ratios, vessel sharpness, and the qualitative results appear to favor spiral and balanced fast field-echo coronary MR angiography sequences, although subjective accuracy for the detection of coronary artery disease was similar to that of other sequences.

Aged↗
PubMed2003

Multi-detector row CT of left ventricular function with dedicated analysis software versus MR imaging: initial experience.

PURPOSE: To determine left ventricular (LV) volumetric and functional parameters from retrospectively electrocardiographically gated multi-detector row computed tomography (CT) by using semiautomated analysis software and to correlate results with those of magnetic resonance (MR) imaging. MATERIALS AND METHODS: In 30 patients (mean age, 59.2 years +/- 7.1 [SD]) known to have or suspected of having coronary artery disease, four-channel multi-detector row CT was performed with standard technique, and diastolic and systolic image reconstructions were generated. With commercially available analysis software capable of semiautomated contour detection, end diastolic and end systolic LV volumes were determined from short-axis secondary CT reformations. Steady-state free-precession cine MR images were acquired in short-axis orientation within 48 hours and analyzed by using dedicated software. Bland-Altman analysis was performed to calculate limits of agreement and systematic errors between CT and MR imaging. RESULTS: Mean end diastolic (138.8 mL +/- 31.9) and end systolic (53.9 mL +/- 21.2) LV volumes as determined with CT correlated well with MR imaging measurements (142.0 mL +/- 32.5 [r = 0.93] and 54.9 mL +/- 22.8 [r = 0.94], respectively [P <.001]). LV ejection fraction (61.6% +/- 10.6 for CT vs 62.3% +/- 10.1 for MR imaging; r = 0.89) and stroke volume (84.6 mL +/- 20.9 for CT vs 86.9 mL +/- 21.5 for MR imaging; r = 0.88) also showed good correlation (P <.001). Bland-Altman analysis showed acceptable limits of agreement (+/-9.8% for ejection fraction) without systematic errors. CONCLUSION: In selected patients, semiautomated analysis software enables LV volumetric and functional analysis based on multi-detector row CT data sets, the results of which correlate well with MR imaging findings.

Aged↗
PubMed2003

Kirner's deformity of all fingers in a 5-year-old girl: soft-tissue enhancement with normal bones on contrast-enhanced MRI.

Kirner's deformity is an uncommon, but characteristic volar-radial incurvature of the distal phalanx of the little finger. We report a 5-year-old girl with dystelephalangy of all fingers. Some members of the mother's family showed dystelephalangy of the little fingers; the father's family history was unaffected. Contrast-enhanced MRI showed enhancement of the soft tissues of the distal phalanges, but no bone deformities. This leads to the assumption that the radial and volar deviation of the distal phalanges is the result of a chronic inflammatory process or a vascularisation disorder of the soft tissue.

Child, Preschool↗