Search PubMed⌕ Search

Biomedical subjects

R Seibel

Publications and source records attributed to R Seibel.

At least 19 recordsLinked to original sources
PubMed2004

Prognostic value of electron-beam computed tomography-derived coronary calcium scores compared with clinical parameters in patients evaluated for coronary artery disease. Prognostic value of EBCT in symptomatic patients.

OBJECTIVE: The electron-beam computed tomography-(EBCT-)derived calcium score provides a measure of coronary atherosclerotic plaque disease which may allow for more precise risk stratification in symptomatic patients. However, it remains unclear if EBCT can add prognostic information compared with the clinical information derived from risk factor assessment, exercise stress testing, and coronary angiography. METHODS AND RESULTS: A cohort of 300 consecutive patients with recent (<3 months) onset of symptoms was retrospectively identified who were examined for possible coronary artery disease (CAD) and who all underwent EBCT. Successful follow-up after 3.5 years was obtained in 255 (85%) patients whose mean age at baseline was 58+/-11 years (n = 181 (71%), males). Four clinical categories with increasing evidence of CAD were constructed on the basis of risk factor assessment, exercise stress testing, coronary angiographic anatomy, and coronary revascularization at baseline. During follow-up, major adverse cardiac events (MACE: myocardial infarction, cardiac death, revascularization) were observed in 40 (16%) patients, including myocardial infarction and cardiac death in 5 patients. The 4 clinical categories were highly predictive of MACE, with a relative risk estimate of 28.3 (95% CI, 6.7-119.1) in the upper vs. the reference category. In univariate analysis, the relative risk estimate of MACE associated with a calcium score > or =100 was 12.0 (95% CI, 4.7-30.6). After adjustment for the clinical categories and for age, this estimate decreased in multivariate analysis, but remained predictive at 4.4 (95% CI, 1.5-12.6). CONCLUSION: In patients with first-time evaluation of possible CAD, EBCT-derived coronary calcium is suggested to provide for independent and additional information compared with the clinically available information.

Adult↗
PubMed2001

Anaphylactic shock from a latex allergy in a patient with spinal trauma.

Allergy to latex is a condition that affects patients as well as health care workers. It is a spectrum of immunologic disorders that ranges from mild hypersensitivity to life-threatening anaphylaxis. Beginning in the early 1970s, the health care community has become more aware of this entity, leading to many improvements in the understanding, diagnosis and treatment of patients with latex allergy. Many hospitals have developed protocols and procedures for patients with latex sensitivity. However, some physicians remain unaware of the logistics of taking care of patients with this disorder. We present a case of a severe anaphylactic reaction to latex in a trauma patient with a spinal cord injury. The difficulty of treating the acutely injured patient with this disorder is illustrated. A list of equipment that may be included in a latex-free emergency kit is provided.

Adult↗
PubMed2001

Natural history and topographic pattern of progression of coronary calcification in symptomatic patients: An electron-beam CT study.

Electron-beam CT may assess the progression of coronary atherosclerosis by visualizing changes in calcification. The present investigation analyzes (1) the rate of progression of calcification in symptomatic patients, (2) the topographic pattern, and (3) the influence of baseline plaque burden and risk factors. Progression of calcification during a mean (median) interval of 18 (15) months was measured in 102 symptomatic outpatients (aged 59+/-9 years, 80% male) with calcification. In 4 patient groups with a baseline total score (Agatston criteria) of 1 to 30, >30 to 100, >100 to 400, and >400, the median was 3.1, 26.1, 58.9, and 109.7, respectively, for absolute annual progression of the score (P<0.05) and 57%, 49%, 32%, and 15%, respectively, for relative progression (P<0.05). On the coronary segmental level, changes were largely restricted to typical predilection sites of coronary atherosclerosis. The presence of angiographically defined coronary narrowing influenced absolute, but not relative, progression. Of the risk factors, only low density lipoprotein cholesterol levels showed a trend, although not significant, for predicting progression. These data indicate that baseline plaque burden determines the rate of progression of calcification. This appears to be a coronary systemic process, reflecting the natural history of coronary atherosclerosis.

Aged↗
PubMed2000

Usefulness of topography of coronary calcium by electron-beam computed tomography in predicting the natural history of coronary atherosclerosis.

Electron-beam computed tomography (EBCT) allows for accurate noninvasive detection and quantification of coronary calcium that is representative of underlying atherosclerotic disease. The present study quantitatively analyzes the topography and establishes the natural history of coronary calcium in patients with variable degrees of coronary atherosclerosis. EBCT was performed in 330 consecutive patients aged 56 +/- 12 years (70% men) with recent (<3 months) onset of signs or symptoms of coronary artery disease (CAD) or who were evaluated because of a presumed high risk. Total calcium scores, computed by the Agatston method, were positive in 269 patients (82%) (mean age 58 +/- 11 years, 73% men). These patients were classified into 4 groups, with total calcium scores ranging between 1 and 30, >30 and 100, >100 and 400, and >400, respectively. The presence and amount of calcium was additionally assessed in 10 major segments of the coronary arterial tree, including the major coronary arteries. Of the 72 patients with calcium of only 1 of the major coronary arteries, the left anterior descending coronary artery was involved in 39 patients (54%) and the right coronary artery in 18 patients (25%). Left main stem calcium was observed in only 10 of 139 patients (7%) with 1- or 2-vessel calcium and in 17 of 77 patients (23%) with 3-vessel calcium. Calcium was consistent most frequently in the proximal left anterior descending coronary artery, followed by the proximal left circumflex and right coronary artery segments. A significant decrease of frequency and amount of calcium from the proximal to distal segments was observed in the left coronary system but not in the right coronary artery, where the distribution was more even. With increasing total calcium scores, segmental scores in the more distal segments were enhanced, but the increase was most pronounced in the proximal segments and particularly in the proximal left anterior descending coronary artery. EBCT-derived coronary calcium shows an axial distribution that appears comparable to that of atherosclerotic lesions observed in pathologic and angiographic studies, highlighting the potential role of EBCT for studying the natural history of CAD.

Aged↗
PubMed2000

Assessment of coronary calcification by electron-beam computed tomography in symptomatic patients with normal, abnormal or equivocal exercise stress test.

AIMS: Exercise stress testing is often used as the initial non-invasive diagnostic test in symptomatic patients with suspected obstructive coronary artery disease. Positive standard ECG criteria are quite specific for obstructive coronary artery disease, but there may be a substantial number of false negative tests, including patients with severe coronary artery disease. Also, exercise stress tests frequently yield equivocal results. Instead of detecting the functional consequences, electron-beam computed tomography visualized atherosclerotic plaque disease directly, but its relationship to functional testing has not been clearly delineated. It was the aim of the current study to examine electron-beam computed tomography for the identification of obstructive coronary artery disease in patients with a normal, abnormal, or equivocal exercise stress test. METHODS AND RESULTS: Symptomatic patients referred for coronary angiography were prospectively included in a consecutive manner if they had no prior diagnosis of coronary artery disease and an unremarkable resting ECG. All patients underwent both exercise stress test and electron-beam computed tomography on the day before coronary angiography. Standard protocols and ECG criteria to diagnose inducible ischaemia were used for the exercise stress test. The electron-beam computed tomography-derived total calcium score was computed according to standard Agatston criteria. Of the 323 patients (mean age, 55+/-11 years; 77% male), 179 (55%) had obstructive coronary artery disease, defined angiographically as luminal diameter narrowing >/=50%. A normal exercise stress test was documented in 105 patients (32.5%), an abnormal exercise stress test ('diagnostic for ischaemia') in 113 (35%), and an equivocal exercise stress test ('inadequate exercise or non-diagnostic ECG-changes') in 105 (32.5%). Multivariate analysis indicated that exercise stress test and electron-beam computed tomography yielded independent information for predicting obstructive coronary artery disease. Sensitivity, specificity and overall accuracy of the exercise stress test were 71%, 75% and 73%, respectively, if equivocal tests were not included, and 50%, 84% and 65% if they were included. Irrespective of the cutpoint regarded as 'positive', the overall accuracy of the electron-beam computed tomography-derived calcium score remained approximately 80% in patients with a normal, abnormal or equivocal exercise stress test. In patients with an equivocal and - to a lesser degree - with a normal exercise stress test, electron-beam computed tomography was able to significantly improve classification regarding obstructive coronary artery disease. Electron-beam computed tomography added no incremental predictive value in patients with an abnormal exercise stress test. CONCLUSION: In patients who are judged to have an intermediate post-test probability of disease after exercise stress test, electron-beam computed tomography scanning may be a meaningful strategy for further stratification regarding the likelihood of obstructive coronary artery disease.

Calcinosis↗
PubMed1999

Ultrasound for the detection of intraperitoneal fluid: the role of Trendelenburg positioning.

A prospective, observational study was performed to evaluate the role of Trendelenburg positioning in improving the sensitivity of the single-view ultrasound examination. Hemodynamically stable patients undergoing diagnostic peritoneal lavage (DPL) were assigned to one of two groups: supine or 5 degrees of Trendelenburg positioning. Baseline right intercostal oblique images of Morison's pouch were obtained followed by additional images for each 100 cc of lavage fluid instilled into the peritoneal cavity. The initial volume of fluid required to identify an anechoic stripe was recorded for each patient. Patients were excluded if they had (1) a positive DPL for hemoperitoneum (defined as 10 cc of gross blood or >100,000 red blood cells/microL), (2) positive baseline ultrasound study, (3) hemodynamic instability, or (4) lack of documentation (ie, baseline/subsequent hard copy images were not obtained or inadequately demonstrated anechoic stripe). The mean quantity of fluid for visualization of the anechoic stripe was 443.8 cc in the Trendelenburg group (n = 8) and 668.2 cc in the supine group (n = 11). These means were statistically different (P < .05, t test). The median amount of fluid needed for visualization of the anechoic stripe was 400 cc and 700 cc for the Trendelenburg and supine groups, respectively.

Abdominal Injuries↗
PubMed1998

Myocardial nuclear factor-kappaB activity and nitric oxide production in rejecting cardiac allografts.

BACKGROUND: Nuclear factor-kappaB (NF-kappaB) is a rapid response transcription factor for genes whose products are critical for inflammation and immunity. In a rat model of heterotopic cardiac transplantation, we studied NF-kappaB DNA binding activity and nitric oxide (.NO) production in untreated allografts and whether inhibition of NF-kappaB suppresses .NO production and prolongs graft survival. METHODS: In allograft recipients and isograft controls, NF-kappaB was assayed by electrophoretic mobility shift assay, daily from transplant until rejection. Myocardial .NO was directly detected in explanted allografts by electron spin resonance spectroscopy on day 6 after transplant. The potent inhibitor of NF-kappaB, pyrrolidine dithiocarbamate (PDTC; 250 mg/kg s.c.) was administered daily from transplant until day of rejection. The extent of graft lymphocytic infiltrate was assessed by routine hematoxylin and eosin staining. Immunohistochemical staining of NF-kappaB was per formed to identify the cell type responsible for NF-kappaB activity. RESULTS: A time-dependent increase in myocardial NF-kappaB activity was seen in untreated allografts as compared with isografts as determined by PhosphorImage analysis. Peak NF-kappaB activity occurred in allografts on day 4 with a ninefold increase as compared with isografts (24.0+/-3.7% vs. 2.7+/-0.5; P<0.05). On posttransplant day 6, electron spin resonance spectroscopy analysis of allografts demonstrated .NO identified by a triplet nitrogen signal centered at g=2.012 with hyperfine splitting of 17.5 Gauss, which is consistent with nitrosoheme formation and low-field signals at g=2.08 and g=2.03 consistent with nitrosomyoglobin. These signals were not seen in native hearts of allograft recipients. With PDTC administration, a threefold decrease in NF-kappaB activity within the transplanted heart was observed on posttransplant day 5 as compared with untreated allografts (9.7+/-1.6% vs. 23.5+/-2.5%; P<0.01). PDTC prolonged graft survival as compared with untreated allografts (11.7+/-0.3 vs. 6.6+/-0.2 days; P<0.05) and reduced the intensity of the nitrosoheme and nitrosomyoglobin signals. Allograft mononuclear cell infiltrate correlated with peak NF-kappaB activity with peak infiltrate on posttransplant day 4. PDTC treatment had no effect on the extent of infiltrate. Immunohistochemical staining localized NF-kappaB to the infiltrating mononuclear cells on posttransplant day 5. CONCLUSION: These data support a role for NF-kappaB in allograft rejection.

Animals↗
PubMed1998

Electron spin resonance analysis of heme-nitrosyl and reduced iron-sulfur centered complexes in allogeneic, heterotopic cardiac transplants: effects of treatment with pyrrolidine dithiocarbamate.

Inhibition of inducible nitric oxide synthase (iNOS) prolongs allograft survival suggesting a role for nitric oxide (.NO) in allograft rejection. Induction of iNOS is regulated by the oxidant-sensitive, nuclear factor kappa B (NF-kappaB) in many cell types. In the present study using electron spin resonance (ESR) spectroscopy, we evaluated whether pyrrolidine dithiocarbamate (PDTC), a metal chelator and antioxidant, might limit .NO production during the development of rejection in cardiac allografts. We performed either isogeneic (Lewis to Lewis) or allogeneic (Wistar-Furth to Lewis) heterotopic abdominal cardiac transplantation. Allograft recipients received daily injections of PDTC or aminoguanidine (a known inhibitor of iNOS). At postoperative days 4 or 6, grafted and native hearts of transplant recipients were flushed with cardioplegic solution to remove blood contamination. ESR data of allografts revealed a triplet nitrogen signal (aN=17.5 G) and centered at g=2.012 and an additional broad signal at g=2.08. This signal was not seen in either isografts or native hearts of either isograft or allograft recipients. Based upon these parameters, these signals are attributed to nitrosomyoglobin. This signal was inhibited by treatment with aminoguanidine or PDTC. Under these conditions, PDTC also prolonged graft survival from 6.6+/-0.2 to 11.7+/-0.3 days. Thus, it is conceivable that nitrosylmyoglobin formation precedes rejection in cardiac allografts and inhibition of nitrosomyoglobin with agents such as PDTC contribute to improved graft survival.

Animals↗
PubMed1998

Comparison of electron-beam computed tomography and intracoronary ultrasound in detecting calcified and noncalcified plaques in patients with acute coronary syndromes and no or minimal to moderate angiographic coronary artery disease.

We compared intracoronary ultrasound (ICUS) and electron-beam computed tomography (EBCT) on a coronary segmental basis in 40 consecutive patients with acute coronary syndromes and no or minimal to moderate angiographic disease (53+/-10 years; 34 men, 6 women). ICUS was used to define plaques, and EBCT was used to quantify coronary calcium (using a threshold of a CT density > 130 Hounsfield units in an area > 1.03 mm2). In a site-by-site analysis, coronary segments were defined as normal if both methods were negative, as containing noncalcified plaques if only ICUS was positive, and as containing calcified plaques if both methods were positive. A total of 222 coronary segments were analyzed (5.6+/-1.9 segments per patient). In 36 patients (90%), a total of 95 segments with plaques were identified, whereas in 4 patients (10%), only normal segments were seen. Of the 95 segments with plaques, 61 (64%) were calcified, and 34 (36%) were noncalcified. There was a linear relationship between the number of segments with calcified and with noncalcified plaques (r = 0.86, p <0.0001), but the mean relative frequency of segments with calcified plaques (55+/-38%) was highly variable. Calcium was found in 15 of 16 patients (93%) with 3 or more segments with plaques, while it was found in only 12 of 20 patients (60%) with one or 2 segments with plaques (p = 0.026). Younger age, higher low-density lipoprotein-cholesterol levels, diabetes, and active smoking predicted a higher relative frequency of segments with noncalcified plaques. Thus, in patients with acute coronary syndromes but no angiographically critical stenoses, there is a linear relationship between segments with calcified plaques versus segments with noncalcified plaques. However, while the mean ratio of these segments is close to 1:1, it is highly variable among individual patients.

Acute Disease↗
PubMed1998

Tomographic microtherapy.

Minimally invasive techniques using endoscopes for image-guided therapy are now common in the field of surgery. Fast real-time radiologic imaging should be integrated into the procedure for increased safety in access and guidance techniques for endoscopes and instruments. The transparency of computed tomography (CT) guidance, magnetic resonance imaging, and electron beam tomography scan techniques allows precise guidance of instruments and endoscopes while permitting their diameter to be minimized. This guarantees safe and transparent access into the body, especially in high-risk areas such as the spine and brain. Combining both technologies has the potential to reduce complications and offers significant advantages in microinvasive operative procedures such as biopsies; local tumor therapy with lasers, radio frequency, or drugs; and percutaneous diskectomies or implants. CT is the golden standard for microtherapeutic procedures because of its precise tip discrimination.

Diagnostic Imaging↗
PubMed1998

Measuring the effect of risk factors on coronary atherosclerosis: coronary calcium score versus angiographic disease severity.

OBJECTIVES: This study sought to determine whether noninvasive quantification of coronary calcium is comparable to selective coronary angiography in measuring the effect of cardiovascular risk factors on coronary atherosclerosis. BACKGROUND: Electron beam computed tomography (EBCT) allows the delineation of anatomic coronary atherosclerotic disease and may be useful for noninvasively defining the role of established and new cardiovascular risk factors in selected patient groups. METHODS: A total of 211 consecutive patients, 26 to 79 years old, referred for evaluation of suspected or recently diagnosed coronary artery disease were examined. Selective coronary angiography was used to define five angiographic disease categories: normal coronary arteries, nonobstructive disease and one-, two- or three-vessel disease. EBCT was used to calculate coronary calcium scores, and cardiovascular risk, including lipid variables and fibrinogen levels, was assessed. RESULTS: Coronary calcium score and angiographic disease severity categories were largely predicted by identical risk factors (i.e., age, male gender, total/high density lipoprotein cholesterol ratio, fibrinogen) and, to a lesser degree, hypertension. Only smoking predicted angiographic disease severity but not calcium scores. The risk factors together explained a comparable proportion of the variability in angiographic disease categories and in calcium score quintiles (33% vs. 41%, p=0.16 by bootstrap analysis). An overall risk score composed of these risk factors separated angiographic disease categories and calcium score quintiles with a similar area under the receiver operating characteristic curve ([mean+/-SE] 0.81+/-0.03 vs. 0.83+/-0.03, p=NS). CONCLUSIONS: Quantification of coronary calcium is comparable to selective coronary angiography in measuring the effect of established cardiovascular risk factors on coronary atherosclerosis. Thus, EBCT may be useful for the noninvasive evaluation of the relations between conventional or developing cardiovascular risk factors and coronary atherosclerosis.

Adult↗
PubMed1998

Dynamic tracking in interventional MRI using wavelet-encoded gradient-echo sequences.

This work describes a newly developed magnetic resonance imaging (MRI) data-acquisition strategy which replaces the standard Fourier phase-encoding with the spatially localized coefficients of wavelet-encoding and offers a new technique for image guidance when combined with a dynamic tracking algorithm. By using this new technique, only a specific fraction of the entire raw data set needs to be updated and reconstructed to visualize the movement of an interventional device during an MR guided procedure. The combination of wavelet-encoding and a dynamic tracking algorithm was implemented in two-dimensional and three-dimensional gradient-echo sequences on a 0.2-T open C-arm-shaped MR system (Siemens, Erlangen Germany) and tested in phantom and in vitro experiments. When applying the wavelet-encoding direction parallel to the movement of a straight interventional device, only those spatially localized wavelet-coefficients mainly affected by the interventional device are updated. This led to potential increases of the image frame rate by a factor of up to seven.

Animals↗
PubMed1997

Coronary artery calcium in acute coronary syndromes: a comparative study of electron-beam computed tomography, coronary angiography, and intracoronary ultrasound in survivors of acute myocardial infarction and unstable angina.

BACKGROUND: Quantification of coronary artery calcified plaques by electron-beam CT (EBCT) may predict cardiovascular events. However, whereas advanced coronary atherosclerotic plaques can be identified, mildly stenotic lipid-rich (soft) plaques may be difficult to detect. The value of EBCT in a subgroup of patients has therefore been questioned. To investigate this, we evaluated patients with acute coronary syndromes by EBCT and compared the results with coronary angiography and, in patients with an indeterminate angiogram, intracoronary ultrasound (ICUS). METHODS AND RESULTS: EBCT was performed in 118 consecutive patients (57+/-11 years of age) with previous myocardial infarction (n=101) or unstable angina (n=17). A standard protocol requiring a CT density >130 Hounsfield units in an area > or =1.03 mm2 was used for the definition of coronary artery calcium. We found that 110 patients had moderate to severe coronary artery disease by coronary angiography, and 8 had either mildly stenotic plaques at a single site (4 patients, confirmed by ICUS) or nonatherosclerotic causes of the unstable coronary syndrome (4 patients). One hundred and five of the 110 patients (96%) with moderate to severe angiographic disease but only 1 of the 8 other patients (13%) had a positive EBCT. Patients with acute coronary syndromes and negative EBCTs were significantly younger than patients with positive EBCTs (46+/-12 versus 58+/-10 years, P<.001), and a higher percentage was actively smoking (100% of the smokers versus 46%, P<.05). CONCLUSIONS: The vast majority of patients with acute coronary syndromes and at least moderate angiographic disease have identifiable coronary calcium by EBCT. Those patients with negative EBCTs have minimal or no atherosclerotic plaque formation. They are younger and tend to be active cigarette smokers.

Acute Disease↗
PubMed1997

Technology and principles of tomographic image-guided interventions and surgery.

Image guidance of instruments can be performed by fluoroscopy, ultrasound imaging, computed tomography (CT), magnetic resonance imaging (MRI), and by stereotactic navigation. During the last year, there has been significant progress in MRI instrument guidance in the field of interventional radiology. Our first 168 clinical cases of MRI-guided interventional procedures, e.g., aspiration biopsy of neoplasms and tomographic microtherapy with local interstitial chemo-ablation, confirm the feasibility of MRI guidance. An expansion of MRI guidance during surgical endoscopic procedures is currently under evaluation and the initial results of this development are presented. Tomographic-guided surgery and the implementation of MRI or CT scanning within the environment of an operating room (OR) entail specific technological requirements and OR design considerations. Fast sequences, interventional protocols, in-room monitor, as well as MR-compatible probes, cannulae, catheters, instruments, endoscopes, and auxiliary equipment that are necessary for this combined surgical image-guided approach are described.

Endoscopes↗
PubMed1997

Comparison of electron beam computed tomography with intracoronary ultrasound and coronary angiography for detection of coronary atherosclerosis.

OBJECTIVES: This analysis compared the results of electron beam computed tomography (EBCT) with those of coronary angiography and intracoronary ultrasound (ICUS) for the in vivo detection of coronary atherosclerotic plaques. BACKGROUND: EBCT is a new imaging modality for identification of coronary calcifications. Coronary angiography depicts advanced changes in coronary morphology, whereas ICUS is an established diagnostic tool that detects the early stages of coronary artery disease. METHODS: In 57 patients (54 +/- 9 years old), 267 coronary segments were analyzed with EBCT (3-mm slices, acquisition time 100 ms, threshold definition of coronary calcification at 130 Hounsfield units in an area > or = 1 mm2, Agatston calcium score), coronary angiography and ICUS. The analysis was based on the number and extent of coronary calcifications on EBCT, coronary lumen reduction on coronary angiography and plaque formation with and without ultrasound signs of calcifications on ICUS. RESULTS: Compared with coronary angiography, EBCT yielded a sensitivity of 66%, a specificity of 78%, a positive predictive value of 39% and a negative predictive value of 91%. Compared with ICUS, EBCT yielded an overall sensitivity of 66%, a specificity of 88% and an overall accuracy of 81%. For plaques with and without ultrasound signs of calcifications, the sensitivity of EBCT was 97% and 47%, specificity 80% and 75% and overall accuracy 82% and 69%, respectively. CONCLUSIONS: This in vivo correlation between ICUS and EBCT demonstrates that EBCT is a noninvasive method that helps to visualize the atherosclerotic process by localization and quantification of coronary artery calcifications. EBCT detects calcified plaques with high accuracy. Plaques without ultrasound signs of calcifications can be detected by EBCT but with lower sensitivity but equivalent specificity.

Adult↗
PubMed1996

Equipment configuration and procedures: preferences for interventional microtherapy.

Magnetic resonance imaging (MRI), computed tomography, and electron beam tomography scanners are built for radiologic diagnosis. With increasing frequency they are being used in the field of interventional Microtherapy to permit transparent visualization of the therapeutic field. Each of these scanners can be combined with endoscopy, fluoroscopy/digital subtraction angiography, and ultrasound units for hybrid imaging techniques as well as with therapeutic systems like lasers or radiofrequency. MRI affords 3D localization without x-ray exposure. Open access and keyhole imaging allow nearly real time guidance of instruments. Minimally invasive techniques using endoscopes and hybrid tomographic guidance result in improved tip tracking of microinstruments and reduced complications. This safer access into the body will lead to interdisciplinary cooperation with the potential for large cost reductions. This report summarizes our experience regarding which of the hybrid imaging suites is best suited for procedures including among others drug instillations, prosthesis (stent) implantation, or microoperations (endoscopic diskectomy/sequestrectomy), and physiological measurements simultaneously.

Diagnostic Imaging↗
PubMed1996

Non-invasive assessment of coronary Palmaz-Schatz stents by contrast enhanced electron beam computed tomography.

UNLABELLED: The aim of the study was the evaluation of electron beam computed tomography as a non-invasive method to localize coronary stents and to document patency in stented vessel segments. METHODS: Twenty-two patients (16m/6f, 58 +/- 7.8 years) with coronary Palmaz-Schatz stents were examined. Contrast enhanced electron beam computed tomography using an Evolution scanner (Siemens) and coronary angiography were carried out within 7 days of each other. Stent localization was performed using the single-slice mode of the electron beam computed tomography scanner. Patency of the coronary target segment was assessed using the multi-slice mode after peripheral venous injection of a 40 ml bolus of contrast medium (Ultravist 370). Qualitative image analysis of a cine loop of 10 consecutive frames and quantitative analysis of densitometric curves in a region of interest distal to the stented vessel segment were performed. RESULTS: All stented vessel segments were identified. In 20 patients (91%), qualitative assessment of contrast enhancement patterns enabled stent patency to be evaluated. In 18 patients (90%), contrast medium was visualized distal to the stent. Quantitative coronary angiography confirmed that the stented vessel segments were not stenosed. Densitometric curves obtained in 16 of these 18 patients yielded contrast enhancement distal to the stented vessel segment of 63 +/- 6% compared to the aorta. In one patient, qualitative and quantitative analysis showed prolonged contrast enhancement of reduced density, which hinted at a stenosis related to the stented vessel segment. Coronary angiography revealed subtotal occlusion of the stented vessel directly distal to the stent. In another patient, no contrast visualization of the vessel distal to the stent was achieved. Coronary angiography revealed complete stent occlusion in this case. CONCLUSION: Electron beam computed tomography can reliably localize coronary stents and may become a useful tool for providing information on stented vessel segment patency.

Adult↗