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Christopher Herzog

Publications and source records attributed to Christopher Herzog.

At least 19 recordsLinked to original sources
PubMed2005

Peripheral artery stent visualization and in-stent stenosis analysis in 16-row computed tomography: an in-vitro evaluation.

The accuracy of 16-row multidetector CT in the visualization of different peripheral artery stents and in the appraisal of in-stent stenosis was assessed. Nine different stent types (nitinol and stainless steel) with three diameters (6, 8 and 10 mm) were used; altogether 27 stents were analyzed in a barrel-shaped vascular model. Low-grade (<40%) and high-grade (>60%) in-stent stenoses were simulated by polyurethane sticks (70 HU) of differing diameters (2-6 mm). Imaging was performed with 16x0.75-mm detector collimation, 130 mAs, 120 kV, 12-mm table feed/rotation, 1.0-mm slice thickness and 0.5-mm increment. The stent diameter, strut thickness, in-stent attenuation values, degree and degree of in-stent stenosis were evaluated. Nitinol stents showed significantly (P<10-6) less stent lumen narrowing, artificial strut thickening and overestimation of the degree of in-stent stenoses than stainless steel stents. In-stent attenuation values and artificial strut thickening were significantly (P<10-6) lower in 10- and 8-mm stents than in 6-mm stents. Stent lumen narrowing was significantly less in 10-mm stents than in 8-mm (P<10-4) or 6-mm (P<10-6) stents. In-stent stenoses were significantly overestimated, irrespective of the stent diameter. In 6-mm stents overestimation was significantly higher than in 8-mm (P<0.01) or 10-mm stents (P<10-6). Under in-vitro conditions 16-row MDCT allowed an accurate identification of in-stent stenosis, but significantly overestimated the effective degree of the stenosis.

Constriction, Pathologic↗
PubMed2005

Percutaneous interventional reconstruction of the iliac arteries: primary and long-term success rate in selected TASC C and D lesions.

We report the primary and long-term outcome of patients with selected TransAtlantic Inter-Society Consensus (TASC) C or D lesions of the iliac arteries after percutaneous interventional reconstruction. Between 1999 and 2001, 89 patients with peripheral arterial disease categorized as TASC C (n=37) and D (n=52) underwent percutaneous interventional reconstruction and stent implantation. Patients were followed for 1-62 months (mean 36 months). Patency rates were assessed by Duplex ultrasound and ankle-brachial index (ABI) measurement. The primary technical success rate was 96.9% with an overall complication rate of 5.6%. The ABI improved from an average of 0.51+/-0.15 before intervention to 0.79+/-0.16 on the day following intervention and to 0.81+/-0.17 within 3 years after intervention. Clinical improvement was observed in 97.3% of the patients in the TASC C group and in 88.5% in the TASC D group. Eighty of 89 patients (89.9%) remained patent at 3-year follow-up. In five patients the reintervention was successful. The secondary patency rate was 95.5%. The patency rates were similar in our selected TASC C and D patients to those so far published for TASC A and B, with low complication rates. Therefore, percutaneous intervention can be recommended for these patients.

Angioplasty, Balloon↗
PubMed2005

Decreased intermediate term patency of automated proximal anastomoses evaluated by sequential ultrafast CT.

OBJECTIVE: The Symmetrytrade mark aortic connector creates proximal anastomoses of saphenous vein grafts using a nitinol implant. The device avoids partial clamping and thus possibly reduces neurologic complications. To evaluate graft patency, a single surgeon randomised study was performed in our institution. METHODS: Seventy-seven patients were randomised either to automated proximal anastomoses (group I, n=39, 61 vein grafts connected using the aortic connector, 47 as single, 15 as sequential bypasses) or controls (group II, n=38, 62 proximal anastomoses handsewn, 46 as single, 16 as sequential bypasses). Ultrafast CT-scans were performed on postoperative day 5 in 34 patients of group I and 16 patients of group II to evaluate early graft patency. Intermediate term patency was evaluated with ultrafast CT-scan in 30 patients of group I (46 grafts) and 25 patients of group II (39 grafts) 1 year after the operation. RESULTS: Two early graft occlusions were detected in group I (3.8%). In group II all evaluated grafts were patent 5 days after surgery. 11.4 months after surgery, seven out of 46 grafts were found occluded (15.2%) in group I. In the control group, only one occlusion was detected (2.6%). CONCLUSIONS: We observed a trend towards an increased occlusion rate 1 year after surgery with automated connector devices. For evaluation of long-term patency larger patient groups have to be evaluated. Other benefits of these devices have to be proven to promote their clinical application.

Adult↗
PubMed2005

Flat-panel detector computed tomography for the assessment of coronary artery stents: phantom study in comparison with 16-slice spiral computed tomography.

PURPOSE: The evaluation of coronary artery stents is a major limitation of cardiac multislice spiral computed tomography (MSCT). The development of flat-panel detector computed tomography (FPCT) with truly isotropic spatial resolution may overcome this limitation. Thus, we evaluated the use of FPCT in comparison to MSCT for the assessment of coronary artery stents. MATERIAL AND METHODS: Eight different coronary artery stents with a diameter of 3 mm each were placed in a static chest phantom. The phantom was positioned in the CT gantry at angles of 0 degrees , 45 degrees , and 90 degrees toward the z-axis and examined with the prototype of a FPCT (Siemens, Forchheim, Germany) and a commercially available 16-detector row MSCT (Sensation 16, Siemens). Slice thickness was 0.25 mm with FPCT whereas for MSCT, an effective slice thickness of 1 mm with a reconstruction increment of 0.5 mm was used. Image quality was assessed visually using a 5-point grading scale. Stent diameters were measured and compared using a repeated-measures analysis of variance. RESULTS: When compared with MSCT, artificial lumen reduction was significantly less using FPCT. On average the visible stent lumen was reduced by 16.1% with FPCT, whereas the mean of the lumen reduction was 47.2% with 16-detector row MSCT. Visible lumen diameter as well as image noise significantly increased using FPCT (P < 0.001). With FPCT delineation of the different stent struts became possible. CONCLUSION: FPCT proved to be superior when compared with 16-detector row MSCT for the in vitro assessment of coronary artery stents. Improved spatial resolution allows for a detailed assessment of the coronary artery stent lumen.

Coronary Angiography↗
PubMed2004

MDCT of the proximal anastomoses created by nitinol implants in coronary artery bypass grafting: a retrospective two-observer evaluation.

The purpose of this study was to investigate the proximal anastomosis of CABG grafts created by a nitinol aortic connector. After receiving CABG, 33 patients underwent CT examination of the heart. On the same patients, CT was performed on postoperative day 5 (4-row CT, group A) and again 1 year thereafter (16-row CT, group B). Twenty-three ACVB to RCX and 27 ACVB to RCA grafts were included. Every anastomosis was reviewed under different reformations (MIP, MPR and VRT). Interobserver correlation was determined. Five days postoperatively, 48/50 anastomoses were classified as patent. One year postoperatively, 42/50 anastomoses were classified as patent. In both groups, the aortic connector could be visualized with good quality: 1.82+/-1.10 (group A) and 1.93+/-1.22 (group B) for ACVB to RCA, similar results for ACVB to RCX grafts (MPR). Image quality at the aortic connector site did not display a significant difference for any reformation between groups (P>0.05). Within groups, MPR displayed better visualization than MIP and VRT (P<0.05). In the presence of metal implants, CT provides reliable data in evaluation of the proximal anastomosis. Sixteen-row CT does not bring a significant benefit to image quality. MPR displayed the best visualization within both groups.

Aged↗
PubMed2004

Visualisation of non-invasive coronary bypass imaging: 4-row vs. 16-row multidetector computed tomography.

UNLABELLED: The purpose of this study was to investigate the image quality of coronary artery bypass graft visualization in 4- and 16-row multidetector CT using multiple imaging reformations. MATERIAL AND METHODS: One hundred sixteen patients underwent CT examination of the heart after receiving CABG. Group A (n=58) received 4-row MDCT; group B (n=58) received 16-row MDCT. Various bypass types such as LITA to LAD and venous grafts to the RCA and RCX were included in the study. A five-point Likert scale was used to grade image quality. Each bypass was reviewed under different imaging reformations: thin slap maximum intensity projection (MIP thin), multiplanar reformation (MPR) and volume rendering technique (VRT). Special attention was paid to the delineation of the distal anastomosis. Interobserver correlation was determined. RESULTS: From 289 bypass grafts examined, 279 (96.54%) were classified as patent and 10 (3.46%) as not patent. Except for the distal anastomosis, 16-row MDCT showed significantly better results for all segments of bypasses. Comparison of reformations within group A and B showed that MIP thin (P<0.05) and VRT (P<0.05) displayed better visualization as compared to MPR. CONCLUSION: Significantly better imaging of all bypass types is possible using 16-row MDCT as compared to 4-row MDCT. Assessment of the distal anastomosis yields no difference between 4- and 16-row technology.

Adult↗
PubMed2004

Extracorporeal shock wave therapy in calcific tendinitis of the shoulder.

OBJECTIVE: To investigate clinical (pain, mobility) and radiological (resolution of calcium deposits) efficacy of different energy levels of extracorporeal shock wave therapy (ESWT) in calcific tendinitis of the shoulder. DESIGN AND PATIENTS: There were 90 study subjects with radiographically verified calcific tendinitis of one shoulder, mean age 52+/-6 years (range 29-65 years; females:males=55:35), all of whom had had symptoms for at least 6 months and substantial restriction of shoulder mobility and pain that required taking anti-inflammatory drugs. Calcium deposits were of type I or type II (clearly circumscribed and dense) and ranged from 1 cm to 3 cm in diameter. Subjects were divided into three groups to receive ESWT at one of two energy levels (E1=0.15 mJ/mm2, E2=0.44 mJ/mm2) or sham treatment. Treatment was given at 6 weekly intervals until symptoms resolved, five treatments had been given or the subject dropped out of the programme. RESULTS: All subjects in groups E1 and E2 completed the programme. Those in group E1 had significantly less pain during treatment but more treatments than those in group E2, and at 6 month follow-up had residual calcification and recurrence of pain (87%). Subjects in group E2 had no residual calcification or recurrence of pain. Sham treatment had no effect. There were no side effects except a small number of haematomas (2 in E1, 6 in E2; maximum size 2 cm). CONCLUSION: ESWT in calcific tendinitis of the shoulder is very effective. It does not have significant side effects at an energy level of E=0.44 mJ/mm2, which can therefore be recommended.

Adult↗
PubMed2004

MR-guided transgluteal biopsies with an open low-field system in patients with clinically suspected prostate cancer: technique and preliminary results.

The purpose of this study was to examine the feasibility and safety of MR-guided biopsies with a transgluteal approach in patients with uncertain or suspicious prostate lesions. Twenty-five patients with uncertain or suspicious focal prostate lesions detected by high-field MR imaging of the prostate gland using endorectal coil imaging were biopsied with a transgluteal approach in a low-field MRI system (0.2 T, Concerto, Siemens). The procedures were guided using T1-weighted FLASH sequences. The prostate gland was biopsied repeatedly with a coaxial technique through a 15-gauge pencil tip with a 16-gauge biopsy handy (median 3.8 samples per patient). Complications and biopsy findings were documented retrospectively. Using T1-weighted sequences biopsy procedures were performed successfully with MR guidance in all cases without any side effects or complications. The median intervention time was 11.3 min. Pathological findings revealed ten cases of hyperplasia or atrophy, three cases of prostatitis, ten cases of carcinoma and two cases of normal tissue. The clinical follow-up showed that in two patients prostate cancer was missed at MR-guided biopsy. Transgluteal MR-guided biopsy of the prostate gland is a safe and promising approach for histological clarification of uncertain or suspicious lesions.

Aged↗
PubMed2004

Virtual endoscopy of the tracheo-bronchial system: sub-millimeter collimation with the 16-row multidetector scanner.

The purpose of this study was to evaluate the scope of sub-millimeter collimation reconstruction parameters using 16-row computer tomography and ECG triggering on image quality in virtual bronchoscopy. Thirty-two patients (5 women, 27 men, mean age 66.6+/-1.4) who had been admitted for coronary artery bypass graft surgery underwent CT examination of the thorax (Sensation 16, Siemens, Inc., Forchheim, Germany). All patients were examined with 16x0.75-mm collimation. Image reconstruction was performed for two groups. In group A ( n=32), slice thickness of 1.5 mm and an overlap of 0.75 mm were used. In group B ( n=32), slice thickness of 0.75 mm and an overlap of 0.4 mm were applied. Retrospective ECG triggering was performed in all patients. The maximum order of recognizable bronchi was determined in each data set. In addition to assessing the maximum order of bronchial bifurcation, bronchial diameter was determined in truly perpendicular sections in each patient. For every segment proximal to a bifurcation, image quality was subjectively graded as poor (grade 1), moderate (grade 2) or good (grade 3). The observers were asked to identify the minimum cardiac movement ECG-triggered image sets assuming that they would be of better quality than the maximum cardiac movement ECG-triggered image sets. The Mann-Whitney U-test and the Fisher's Exact Test were used for statistical evaluation. In group A, a mean of 4.8+/-0.2 bifurcations was ascertained vs. 6.5+/-0.3 bifurcations in group B [ P<0.0003]. For bronchial diameters in group A, a mean of 7.5+/-0.4 mm was determined vs. 4.6+/-0.4 mm in group B [ P<0.0001]. In group B, two independent radiologists observed a significant shift to better image quality in all segments evaluated [ P<0.006 to P<0.000001]. Motion artifacts were judged as being significantly reduced by minimum cardiac movement ECG-triggering in group B [observer 1: P=0.0007 (20/32); observer 2: P=0.008 (18/32)], but not in group A [observer 1: P=0.286 (13/32); observer 2: P=0.123 (16/32)]. Sub-millimeter collimation and minimum cardiac movement ECG-triggered data acquisition allow deeper penetration into the tracheo-bronchial system allowing visualization of the bronchial surface down to diameters below 5 mm in certain cases up to the eighth bifurcation. Along with an enhanced visualization as such, better image quality is acquired in all segments evaluated. Trade off between better image quality, of doubtful diagnostic consequence, and much higher irradiation dose must be made.

Aged↗
PubMed2004

Interstitial photodynamic laser therapy in interventional oncology.

Photodynamic therapy (PDT) is a well-investigated locoregional cancer treatment in which a systemically administered photosensitizer is activated locally by illuminating the diseased tissue with light of a suitable wavelength. PDT offers various treatment strategies in oncology, especially palliative ones. This article focuses on the development and evaluation of interstitial PDT for the treatment of solid tumors, particularly liver tumors. The PDT is mostly used for superficial and endoluminal lesions like skin or bladder malignancies and also more frequently applied for the treatment of lung, esophageal, and head and neck cancer. With the help of specially designed application systems, PDT is now becoming a practicable option for solid lesions, including those in parenchymal organs such as the liver. After intravenous treatment with the photosensitizer followed by interstitial light activation, contrast-enhanced computed tomography shows the development of therapy-induced necrosis around the light-guiding device. With the use of multiple devices, ablation of liver tumors seems to be possible, and no severe side effects or toxicities related to the treatment are reported. PDT can become a clinically relevant adjunct in the locoregional therapy strategies.

Humans↗
PubMed2004

Successful treatment of deep sternal infections following open heart surgery by bilateral pectoralis major flaps.

OBJECTIVES: Severe sternum necrosis requiring extended resection necessitates plastic reconstruction of the resulting defect and stabilization of the chest. We analyzed the outcome of patients undergoing bilateral pectoralis major flap repair on functional and cosmetic results, chest stabilization and pulmonary function. METHODS: Twelve patients undergoing cardiac surgery between 1997 and 2001 suffered from a deep mediastinal wound infection and sternum necrosis. After a mean of two attempts of extensive wound debridement, all 12 patients underwent complete sternal resection with plastic reconstruction by bilateral pectoralis major flaps. Risk factors were obesity (n=10) and diabetes (n=11). Six months postoperatively patients underwent physical examination, pulmonary function testing and functional CT scan. RESULTS: Three patients died in hospital (two septic multiorgan failure, one heart failure) and nine were discharged with complete wound closure. One patient suffered a lethal stroke during follow-up. At 6-month follow-up no recurrent sternum infection had occurred. Chest stability was satisfactory without impairment of pulmonary function (VC 77.5+/-12.1% at follow-up vs 77.8+/-12.5% preoperatively). Mobility and force of arms and shoulder were adequate; at CT scan the maximum distance change between the former sternoclavicular joint in inspiration versus expiration was minimal. Quality of life questionnaires showed no significant limitations except a disturbed sleep and mild restriction of executing hobbies and social activities. CONCLUSIONS: Bilateral pectoralis major flap repair is a safe technique to cure severe mediastinitis necessitating complete sternal resection. Wounds close without extensive reconstructive surgery. Cosmetic results as well as stabilization of the chest were good. Patients reported an almost uncompromised quality of life without respiratory impairment.

Aged↗
PubMed2004

Automatic connector devices for proximal anastomoses do not decrease embolic debris compared with conventional anastomoses in CABG.

OBJECTIVE: Emboli generated during cardiac surgery have been associated with aortic clamping and manipulation. Proximal anastomotic devices are thought to be less traumatic by eliminating partial clamping, potentially resulting in fewer adverse outcomes. Intra-aortic filtration has been shown to effectively capture particulate debris. We compared the amount of debris released using intra-aortic filtration and the clinical outcomes between conventionally handsewn and automated proximal anastomoses. METHODS: Seventy-seven patients undergoing primary coronary artery bypass grafting with cardiopulmonary bypass were enrolled in a prospective randomized study. Patients were assigned to the anastomotic device Group I (Symmetry Aortic Connector, n = 39) or the conventional handsewn anastomosis control Group II (n = 38). Proximal anastomoses were performed before cardiopulmonary bypass in both groups. Intra-aortic Filter 1 (EMBOL-X)was deployed prior to partial clamping or puncturing the aorta for device application and removed after the proximal anastomosis was completed. Prior to cross-clamp removal, a second filter was inserted (Filter 2). A core laboratory performed quantitative and histologic analyses of the debris captured. Clinical outcomes included adverse events, neurocognitive test scores, graft patency, and mortality. RESULTS: Preoperative variables and risk factors were not significantly different between Groups I and II (EuroSCORE 3.9+/-2.6 vs. 4.2+/-2.5). Filter analyses showed no significant difference between Groups I and II in Filter 1 or 2 for either surface area of particles or total number of particles (P> 0.005). There was a significant decrease between Filters 1 and 2 in both Groups for surface area of particles (Group I: 18.5+/-23.8 mm2 vs. 10.7+/-16.3 mm2, P = 0.017; Group II: 15.0+/-15.4 mm2 vs. 6.9+/-.6.5 mm2, P = 0.004), and for total number of particles in Group II (8.6+/-3.7 vs. 7.1+/-2.4, P = 0.023). No significant differences were observed between Group I (device) and Group II (control) outcomes for myocardial infarction, neurocognitive deficit, stroke, length of stay, graft occlusion, or mortality. CONCLUSIONS: The application of proximal aortic connectors without partial clamping does not reduce particulate emboli or affect clinical outcomes compared with conventional anastomoses. Cross-clamping during cardiopulmonary bypass produces less particulate debris than conventional or automated proximal anastomoses performed off-pump, suggesting a major source of emboli is the anastomotic process.

Adult↗
PubMed2004

Progress in CT imaging for the cardiac surgeon.

The aim of this article is to critically assess the role of multidetector-row CT (MDCT) in the field of cardiothoracic surgery. In the beginning, a short overview is given about technical aspects such as scan protocols, optimal image reconstruction, image reformation techniques, data evaluation, and data presentation. This is followed by sections about possible indications for cardiothoracic surgery and future prospects for this technology. For the cardiac surgeon, the main benefit of MDCT lies in the combination of large scan-volume coverage, high spatial resolution, proper identification of calcifications, and the simultaneous registration of other thoracic structures. Preoperative applications may include the assessment of cardiac valves, noninvasive evaluation of large thoracic vessels, staging of cardiac tumors, and planning of minimally invasive surgical procedures. After surgery, MDCT examinations particularly facilitate an early identification of severe postoperative complications. MDCT may also be used to assess coronary artery bypass graft patency and to identify transplant-related complications in heart transplant recipients at an early stage. New technological developments such as 64-row MDCT or flat panel computed tomography will further increase the field of possible indications.

Coronary Artery Bypass↗
PubMed2003

Multidetector-row cardiac CT: diagnostic value of calcium scoring and CT coronary angiography in patients with symptomatic, but atypical, chest pain.

The aim of this study was to investigate the accuracy of multidetector-row cardiac CT (MDCT), calcium scoring (Ca-Sc), and MDCT coronary angiography (MD CTA) in the assessment of coronary atherosclerosis. Thirty-eight patients underwent invasive coronary angiography (CA) and MDCT (collimation 4x1 mm, pitch 1.5 mm, TI 500 ms, 120 kV, 300 mAs, and retrospective ECG-gating). Calcium scoring was calculated for the total coronary artery territory and for RCA, LCA, and LCX separately. The MD CTA served to assess the degree and the localization of stenoses. All findings were compared to invasive coronary angiography. Approximately 68.4% (390 of 570) of all coronary segments could be visualized by MDCT. Correlation coefficient for MD CTA and CA amounted to r=0.58, showing distinct differences for the individual segments. Proximal segments generally showed better correlation (range 0.81-0.77) than medial segments (range 0.91-0.20), distal segments (range 0.55-0.04), or side branches (range 0.76-0.00). Patients with hemodynamically relevant (>75%) stenoses were detected by MD CTA with 72.2% sensitivity (13 of 18) and 100% specificity (20 of 20). For Ca-Sc sensitivity ranged between 94.7% (17 of 18) and 66.7% (12 of 18), specificity between 20% (4 of 20) and 80% (16 of 20) respectively, depending on the prevailing cutoff value. Combination of both methods led to 83.3% sensitivity (15 of 18) and 100% specificity (20 of 20), reaching no level of significance as compared with Ca-Sc (p=0.73) or MD CTA (p=0.23) alone. Calcium scoring as a single method showed highest sensitivity in the detection of coronary atherosclerosis but at the expense of low specificity. In patients with no or moderate calcifications, combination with MD CTA helped to distinctly increase specificity and NPV.

Adult↗
PubMed2003

Multidetector-row CT: cardiosurgery indications.

This article critically evaluates the role of multidetector-row CT before and after cardiosurgical procedures. In addition, technical aspects, such as scan protocols, optimal image reconstruction intervals, image reformation techniques, and data evaluation, are presented and briefly discussed.

Aortic Valve↗
PubMed2003

Multi-detector row CT versus coronary angiography: preoperative evaluation before totally endoscopic coronary artery bypass grafting.

PURPOSE: To assess multi-detector row spiral computed tomography (CT) for preoperative evaluation of patients undergoing totally endoscopic coronary artery bypass grafting and to correlate the data with coronary angiographic and intraoperative findings. MATERIALS AND METHODS: Thirty-six patients preoperatively underwent multi-detector row CT (4 x 1-mm collimation, pitch of 1.5, 500-msec rotation time, retrospective electrocardiographic gating, 1.25-mm effective section thickness) and coronary angiography. Assessment criteria for both techniques were visibility and cardiac course of coronary arteries, localization and degree of stenoses, composition of atherosclerotic plaques, and vascular diameter at anastomosis site. Site for distal bypass anastomosis was recommended. Results at multi-detector row CT were calculated relative to results at coronary angiography and surgery. RESULTS: Multi-detector row CT properly displayed 79.4% (154 of 194) of all surgical relevant coronary segments and 80.4% (434 of 540) of all coronary segments. For coronary angiography, ratios of 88.7% (172 of 194) and 94.6% (511 of 540), respectively, were observed. For detection of calcified plaques, multi-detector row CT results exceeded those at coronary angiography by a difference of 17% (18 of 18 [100%] compared with 15 of 18 [83%]). Hemodynamically relevant stenoses were identified with multi-detector row CT in 76% (42 of 55) of cases. Bridging of coronary segments through either myocardium (four of five) or epicardial fat (two of three) was better identified at multi-detector row CT than it was at coronary angiography (one of five compared with zero of three, respectively). At multi-detector row CT, 76% (28 of 37) of all distal bypass touchdown segments were identified, but at coronary angiography, only 70% (26 of 37) were identified. CONCLUSION: Multi-detector row CT provides extended information about coronary target site and therefore should be regarded as an ideal additive planning tool for complex minimally invasive procedures such as totally endoscopic coronary artery bypass grafting or minimally invasive direct coronary artery bypass grafting.

Adult↗