Biomedical subjects

M Reiser

Publications and source records attributed to M Reiser.

At least 37 records · Page 2Linked to original sources

PubMed2006

[Soft tissue manifestations of early rheumatic disease: imaging with MRI].

PURPOSE: The aim of this study was to evaluate typical magnetic resonance imaging (MRI) findings in early rheumatic diseases manifesting at the soft tissues of the hand using a retrospective analysis. MATERIAL AND METHODS: A total of 186 MRI examinations of patients with clinical suspicion of a rheumatic disease were evaluated in a consensus reading by two experienced radiologists. All imaging patterns were assessed with respect to their type and localization. Under blinded and non-blinded conditions diagnoses were correlated with final clinical diagnosis. RESULTS: The most frequent diagnoses were rheumatoid arthritis (RA, 45.7%) and psoriatic arthritis (PsA, 15.6%). The mean correlation between clinical and MRI diagnosis (r) was 0.75 in blinded and 0.853 in non-blinded reading (p <0.001). The following extra-articular imaging patterns were found: synovitis (59.1%), tendovaginitis (91.4%), dactylitis (14.5%), and bone marrow edema (18.3%). Only dactylitis was specific for a particular rheumatic disease (PsA; r=0.934; sensitivity 84.9%, specificity 82.4%). CONCLUSION: Inflammatory conditions of the hand can be reliably detected with MRI. In many cases the definite diagnosis can only be made when taking clinical, serological, and radiographic results into account (+13.7% increase of significance).

Adult↗

PubMed2006

[Chronic critical ischemia of the lower leg: pretherapeutic imaging and methods for revascularization].

Each year 1-2% of patients with peripheral arterial occlusive disease (pAOD) develop critical limb ischemia (CLI), characterized by rest pain and peripheral ulcer or gangrene. This aggravation of the disease is accompanied by an increase of the 1-year mortality rate up to 25% and a similarly increased frequency of major amputation. We can choose between conservative, endovascular, and surgical procedures for an adequate therapy of the underlying vascular stenoses or occlusions. Yet, clear therapeutic recommendations only exist for suprapopliteal lesions. However, in a number of cases, especially in diabetics, target lesions have an infrapopliteal location. Since endovascular procedures have undergone significant improvement in the last few years, the following review discusses methods for infrapopliteal revascularization taking into consideration the newest publications on this topic.

Angioplasty↗

PubMed2006

[Stenting of the SFA--indications, techniques, results].

Aggressive risk factor modification, change of eating habits, exercise programs, and forceful antiplatelet therapy are the most important tools for the treatment of PAOD in symptomatic patients suffering from intermittent claudication. There are however no guidelines for revascularization at this stage. Endovascular treatment has been increasingly utilized over the last decade and increasingly displaced vascular surgery. Amongst numerous endovascular techniques beside PTA, stents meanwhile play the most important role due to constant technical progress. Results regarding the rate of restenosis or patency rates still remain worse compared to other vascular beds. This paper gives a review over recent results, currently available stent techniques, and possible indications for the endovascular therapy of an artery, which has turned out to be the biggest ordeal for material and construction of stents.

Blood Vessel Prosthesis↗

PubMed2006

[Intravascular optical coherence tomography: differentiation of atherosclerotic plaques and quantification of vessel dimensions in crural arterial specimens].

PURPOSE: Intravascular optical coherence tomography (OCT) is a new technique based on infrared light that visualizes the arteries with a resolution of 10-20 microm. Intravascular ultrasound (IVUS) is the current in vivo reference standard and provides a resolution of 100-150 microm. This study compared OCT to IVUS and histopathology with respect to the ability to differentiate atherosclerotic plaques and quantify vascular dimensions in peripheral crural arteries ex vivo. MATERIALS AND METHODS: 50 segments of atherosclerotic arteries derived from five amputated human lower extremities were examined. The different plaque types (fibrous, high-lipid content, calcified) were assigned by two independent examiners, and the sensitivity and specificity of OCT in comparison with histopathology as well as intra- and interobserver consensus were calculated. A comparison of OCT with IVUS addressed the parameters: luminal area (LA), vascular wall area (VA) and plaque area (PA). RESULTS: When comparing OCT and histopathology with respect to the differentiation of various plaque types, sensitivities of 81 % and specificities of 89 % for fibrous plaques, of 100 % and 93 % for lipid-rich plaques and of 80 % and 89 % for calcified plaques were achieved (overall correlation 83 %). Intra- and interobserver consensus was very high (kappa = 0.86 and kappa = 0.89, p < 0.001, respectively). There was also a high correlation between quantitative measurements (Bland-Altman plot [LA]: mean bias, 0.1 mm(2) accuracy +/- 1.8 mm(2), r = 0.95 [p < 0.001] Bland-Altman plot [VA]: mean bias, 0.3 mm(2) accuracy +/- 2.3 mm(2), r = 0.94 [p < 0.001] Bland-Altman plot [PA]: mean bias, 0.4 mm(2) accuracy +/- 2.3 mm(2), r = 0.80 [p < 0.01]. CONCLUSION: OCT allows the differentiation of atherosclerotic plaque types in crural arteries with high accuracy compared to histopathology. Quantitative measurements show a high correlation with IVUS, the current reference standard.

Atherosclerosis↗

PubMed2006

[Ultrasound guided implantation of chest port systems via the lateral subclavian vein].

PURPOSE: Retrospective analysis of the success and complication rates of chest port implantation via the lateral subclavian vein. MATERIALS AND METHODS: Between January 2003 and June 2004, the lateral subclavian vein in 271 patients (186 women, 85 men, mean age 53.2 years) was punctured guided by ultrasound. This access was used to insert a port system, and the catheter tip was placed at the cavoatrial junction. The port reservoir was implanted in a subcutaneous infraclavicular pocket and fixed to the fascia of the pectoralis muscle. Indications for port implantation were chemotherapy (n = 239), total parenteral nutrition (n = 2) and intravenous medication (n = 30). The patient follow-up was mainly performed either by the oncology division of the department of gynecology or by the department of internal medicine. RESULTS: A chest port catheter system was successfully implanted in all patients. The catheter remained in place for a mean duration of 269.4 days (SD 192.3 days). No complications occurred during implantation. In the post-interventional period, 6 catheter dysfunctions were found (thrombotic 0.09 per 1000 catheter days; mechanic 0.05 per 1000 catheter days). While one local infection occurred in the early post-interventional period, 3 local and 15 systemic infections were independent of the port catheter placement (0.39 per 1000 catheter days). The rate of port catheter ex-plantation due to dysfunction or infection was 0.07 per 1000 catheter days. CONCLUSION: Ultrasound-guided puncture of the lateral subclavian vein is a safe procedure for the insertion of central venous port catheter systems and had a very low complication rate in our study. For further evaluation of our port placement technique, prospective studies compared to placement through the internal jugular vein are necessary.

Catheterization, Central Venous↗

PubMed2006

[Impact of a PACS/RIS-integrated speech recognition system on radiology reporting time and report availability].

PURPOSE: Quantification of the impact of a PACS/RIS-integrated speech recognition system (SRS) on the time expenditure for radiology reporting and on hospital-wide report availability (RA) in a university institution. MATERIAL AND METHODS: In a prospective pilot study, the following parameters were assessed for 669 radiographic examinations (CR): 1. time requirement per report dictation (TED: dictation time (s)/number of images [examination] x number of words [report]) with either a combination of PACS/tape-based dictation (TD: analog dictation device/mini-cassette/transcription) or PACS/RIS/speech recognition system (RR: remote recognition/transcription and OR: online recognition/self-correction by radiologist), respectively, and 2. the Report Turnaround Time (RTT) as the time interval from the entry of the first image into the PACS to the available RIS/HIS report. Two equal time periods were chosen retrospectively from the RIS database: 11/2002 - 2/2003 (only TD) and 11/2003 - 2/2004 (only RR or OR with speech recognition system [SRS]). The mid-term (> or = 24 h, 24 h intervals) and short-term (< 24 h, 1 h intervals) RA after examination completion were calculated for all modalities and for CR, CT, MR and XA/DS separately. The relative increase in the mid-term RA (RIMRA: related to total number of examinations in each time period) and increase in the short-term RA (ISRA: ratio of available reports during the 1st to 24th hour) were calculated. RESULTS: Prospectively, there was a significant difference between TD/RR/OR (n = 151/257/261) regarding mean TED (0.44/0.54/0.62 s [per word and image]) and mean RTT (10.47/6.65/1.27 h), respectively. Retrospectively, 37 898/39 680 reports were computed from the RIS database for the time periods of 11/2002 - 2/2003 and 11/2003 - 2/2004. For CR/CT there was a shift of the short-term RA to the first 6 hours after examination completion (mean cumulative RA 20 % higher) with a more than three-fold increase in the total number of available reports within 24 hours (all modalities). The RIMRA for CR/CT/MR was 3.1/5.8/4.0 in the first 24 hours, and 2.0 for XA/DS in the second 24-hour interval. CONCLUSION: In comparison to tape-based dictation, an SRS results in a significantly higher primary time expenditure and a modified report dictation workflow. In a university institution, a PACS/RIS-integrated SRS achieves a marked improvement in both short- and mid-term RA which eventually results in an improvement in patient care.

Efficiency, Organizational↗

PubMed2006

[Comparison of different review displays with respect to the detection of low-contrast details in digital radiographs].

PURPOSE: Assessment of low-contrast details in digital radiographs on different review displays (RD). MATERIALS AND METHODS: 20" flat screen panels (RD1: standard color LCD-TFT, RD2: monochrome LCD-TFT for radiological reading, RD1*: RD1 with optional image inversion; 205 cd/m (2) luminance, respectively) were evaluated. At 30 lx ambient lighting, 10 radiologists gradually increased the contrast (constant steps) for both a homogeneous picture and a cutout of a thorax radiography of n = 480 simulated nodules until they became recognizable. RESULTS: In the case of bright nodules on an anthropomorphic background, the use of image inversion produced significantly better results. No other significant differences were detected. CONCLUSION: Provided that the working environment is not bright, the results suggest that low-cost RD can be used for the recognition of low-contrast details in radiographies of the chest. Further studies including more display models are necessary. Among different ambient lighting and luminance settings, these studies should include a closer analysis of the special features of digital systems such as brightness/contrast adaptation, picture enlargement (zoom shot), and image inversion.

Equipment Design↗

PubMed2005

Task difficulty in a simultaneous face matching task modulates activity in face fusiform area.

The level of difficulty of a task can alter the neural network that activates for performance of the task. Previous studies have shown increased activation with task difficulty in the frontal lobes while the effects in the extrastriate visual areas have been unclear. We hypothesized that the face fusiform area (FFA), an area specialized for face processing, would increase activation as task difficulty increased in a face matching task. The difficulty level was increased by degrading the quality of the images. The degradation levels were 10%, 20%, 40% and 60%. Based on the correct response rate, the data were divided into a baseline level (composed of non-degraded and 10% degraded images) and a difficult level (composed of the 20%, 40% and 60% degraded images). Brain activation was measured using functional magnetic resonance imaging. The baseline face matching task activated a wide network of regions that included bilaterally the occipital, temporal and parietal lobes and the right frontal lobe. A novel behavioral finding was that task difficulty did not linearly increase with image degradation. The novel brain imaging finding was that the FFA is modulated by task difficulty and performance in the task was linearly correlated to activation in FFA. In addition, we found that activation in the dorsolateral prefrontal cortex (DLPFC) had increased activation as task difficulty increased. When adding the response time as a covariate, the differences in the DLPFC did not remain statistically significant. Increased task difficulty also led to a decrease in activation of visual areas in the extrastriate cortex. Task difficulty increased activation in the FFA to enhance the face processing and suppressed activation in visual extrastriate areas that processed low level properties of the stimuli. Task difficulty led to enhanced response in the FFA and suppressed response in other visual areas.

Adult↗

PubMed2005

Cine magnetic resonance imaging vs high-resolution ultrasonography for detection of adhesions after laparoscopic and open incisional hernia repair: a matched pair pilot analysis.

BACKGROUND: Intraabdominal adhesions represent nonspecific complications before or after laparoscopic or open incisional hernia repair. The objective of this matched control pilot study was to display long-term adhesions noninvasively by applying functional cine magnetic resonance (MR) imaging, as compared with applying high-resolution ultrasonography (US). METHODS: The study group, composed of 17 consecutive patients (12 men and 5 women; mean age, 52 years), underwent laparoscopic intraperitoneal onlay mesh repair using expanded polytetrafluoroethylene (ePTFE) mesh. Their mean body mass index was 30 kg/m(2), and the size of the hernia was 95 cm(2). Another group, matched for age, gender, and type of hernia, was subjected to open abdominal wall repair using the preperitoneal sublay technique with a large-pore, low-weight polypropylene mesh. For cine MR imaging (1.5 T), section-by-section dynamic depiction of induced visceral slide throughout the entire abdomen was achieved by applying transverse or sagittal true fast imaging with steady-state precession sequences. The location and type of adhesions were compared with high-resolution ultrasonography using nine segments of the abdominal map. RESULTS: The patients subjected to laparoscopic and open incisional hernia repair were examined 16 and 28 months after surgery. The findings showed functional cine MR imaging as superior to high-resolution ultrasonography for assessing the amount of intraabdominal adhesions (n = 53 vs n = 3; p < 0.01). Most frequently, adhesions were seen between small bowel loops and the abdominal wall (n = 22), followed by bowel-to-bowel adhesions (n = 19; p < 0.05). However, adhesions between small bowel loops and the abdominal wall occurred more frequently after open mesh repair (p < 0.05). Furthermore, a strong correlation was observed between patient complaints and findings with cine MR imaging (p < 0.05). Maximum pain correlated significantly with the region of the most distinctive adhesions (p < 0.05). CONCLUSIONS: Functional cine MR imaging represents a reliable noninvasive technique for detecting long-term adhesions after open and laparoscopic incisional hernia repair. The study results suggest that this approach has distinct advantages over high-resolution ultrasonography.

Adult↗

PubMed2005

Cerebral perfusion pressure for prediction of recurrent intracranial hypertension after primary decompressive craniectomy.

BACKGROUND: Decompressive craniectomy (DC) with dural grafting may be performed in patients with moderate (Glasgow-Coma-Scale [GCS] score 9-12 points) or severe traumatic brain injury (TBI; GCS score <or= 8 points) and threatening herniation. However, its effectiveness especially after primary craniectomy is still discussed due to missing evidence of improved outcome. The objectives of this study were to show the incidence of recurrent intracranial hypertension after primary DC, to identify predictive parameters for secondary DC, and to evaluate the long-term neurological performance 12 months after TBI. METHODS: Between 01/1997 and 06/2001 all consecutive patients admitted with moderate or severe isolated TBI were enrolled in this study. They were treated according to the guidelines of the European Brain Injury Consortium, and the American Association of Neurosurgical Surgeons (AANS) for the management of severe TBI. Process and clinical data as well as every intervention were registered prospectively. The long-term neurological status was reassessed using the Glasgow Outcome Score (GOS) 12 months after TBI. Statistical comparison was performed using Mann-Whitney-U test, and multivariate testing by means of logistic regression analysis. RESULTS: Fifty-one (43 males, 8 females; median age 51.4 years) of 119 isolated TBI patients were included. Ten patients (8 males, 2 females; median age 38.4 years) underwent secondary extended or contralateral DC in their clinical course. Three of them (30%) died at a median of 1 day after revision respectively 6 days after TBI. According to univariate analysis, secondary DC significantly correlated with arterial hypotension (p = 0.020) and otorrhagia at admission (p = 0.041), skull base fracture (p = 0.011) and decreased maximum cerebral perfusion pressure (CPP; p = 0.006) after primary surgery. Multivariate analysis identified decreased maximum CPP as the only independent predictive parameter (p = 0.036) for secondary DC and unfavourable GOS after 12-months follow-up. CONCLUSION: Arterial hypotension, otorrhagia at admission and skull base fractures are negatively influencing the mortality and morbidity of patients with isolated moderate or severe TBI. However, only decreased maximum CPP may independently indicate secondary DC after primary craniectomy in case of recurrent intracranial hypertension.

Adult↗

PubMed2005

Observation of the anomalous increase of the longitudinal energy spread in a space-charge-dominated electron beam.

We report a new experimental study of the growth of longitudinal energy spread in a space-charge-dominated electron beam, with a beam energy of several keV and beam current of approximately 100 mA. At relatively low beam densities, we measure growing energy spreads with distance along the transport channel, which are in remarkably good agreement with the theory of energy relaxation via Coulomb collisions. At higher beam densities, however, anomalous energy spreads exceeding the predictions of the relaxation theory are observed, which, we believe, could be caused by collective longitudinal-transverse instabilities observed in computer simulation studies. The onset of these instabilities occurs after several plasma periods according to calculations.

Journal Article↗

PubMed2005

Differential activation of pre-SMA and SMA proper during action observation: effects of instructions.

Many neurophysiological studies give evidence for a matching system between action observation and imitation. We used functional MRI to investigate the effects of different instructions for observing identical stimuli of whole-body gymnastics movements. The imitative-like observation mode asked normal human participants to observe the sequence containing repetitive parts and to subsequently imagine the observed movements in the first-person perspective. The evaluative observation mode asked the participants to carefully observe and judge movement accuracy and consistency in the repetitive sequence. We hypothesized that the supplementary motor area would be specifically involved in performing the observational tasks. Results indicate that the SMA proper is generally activated during observation of whole-body gymnastic movements and shows pronounced activation in imitative-like observation mode. Pre-SMA activity can be differentially modulated by instructions related to the observation task.

Adult↗

PubMed2005

[Liver tumor ablation].

Minimal-invasive techniques for ablation of primary and secondary hepatic tumors gain increasingly clinical importance. This is especially true since surgical resection and classic chemotherapy is successful only in a limited number of patients. Local ablative methods incorporate chemo- (percutaneous alcohol instillation, transarterial chemoembolization), thermo- (radiofrequency-, laser-, microwave-, cryoablation, high intensive focused ultrasound) and radio-ablative techniques (interstitial brachytherapy, selective internal radiotherapy). Regarding their implementation and specific effects these methods are varying widely, nevertheless all of them have a high therapeutical efficacy together with a low complication rate in common-correct application presumed. The knowledge on specific indications and contraindications is crucial to implement these methods into multimodality therapy concepts.

Brachytherapy↗

PubMed2005

[Clip marker placement following MR-guided vacuum biopsy of the breast].

PURPOSE: The purpose of our study was to determine the placement accuracy, usefulness as a guide for wire localization, and long-term stability of tissue marker clips following MR-guided vacuum-assisted biopsy (VB) of breast lesions. METHODS: During a 2-year period, MR-guided VB with an 11-gauge device was performed in 79 lesions. In 26 lesions a marker clip was placed at the biopsy site. RESULTS: In 18 cases, the clip was shown to be closely adjacent to the lesion on post-interventional MR images. In seven cases in which minor bleeding occurred, the clip dislocated (< or =15 mm) in the direction of the needle pathway. In one case dislocation in the dorsal direction (< or =5 mm) was observed. In eight cases with a malignant or borderline histology according to the VB, the marker clips served as targets for mammographically guided wire localization. In all of those patients, histology results derived from open surgery confirmed those of VB. Eighteen patients with benign findings according to the VB were followed up 6 months later. Among these cases we found a significant displacement of the marker clip in one case (3 cm). The clip generally caused a round artifact (diameter of 9+/-2 mm). In two cases it was not possible to determine whether the lesion had been removed completely or was just behind the artifact caused by the clip. CONCLUSION: Based on our results, clip marker placement following MR-guided vacuum biopsy should be called into question due to the possibility of masking the lesion by a metallic artifact and because of possible dislocation.

Adult↗

PubMed2005

[Sonographically guided, minimally invasive biopsy of uncertain mammary lesions. Clinical experience with a new biopsy system].

METHODS: We performed Vacora biopsy on 53 patients for minimally invasive breast diagnostics. Each histologically malignant lesion underwent surgery. The histopathology of the Vacora biopsy was then compared to the surgical report. When there was a discrepancy between Vacora histopathology and the report, the patient underwent open biopsy. In all patients with benign histopathology results, sonography was performed 5-7 days after biopsy and after 3 months. RESULTS: We performed biopsies on two lesions in eight patients, and on three lesions in one patient. Mean age of the patients was 52.1+/-12.8 years. A total of 62 lesions were examined. Mean size of the lesions was 13.3+/-9.6 mm. Fourteen (26.4%) were malignant (n=2 DCIS, n=12 invasive carcinoma). Histological grading was identical for Vacora biopsy and the surgical specimens. One case showed ADH by Vacora biopsy, which was confirmed by open biopsy. Vacora biopsy generated one false negative. There were a total of 36 benign lesions. CONCLUSION: Vacora biopsy under sonographic guidance is a method which is easy to handle, diagnostically accurate and without severe complications. Due to higher costs in comparison to high speed core biopsy, Vacora biopsy should be performed only in cases in which high speed core biopsy is not expected to result in a valid result.

Adult↗

PubMed2005

[O-twist marker for post-interventional marking in imaging of suspected breast lesions].

AIM: The aim of this study was to develop a marker clip for use in minimally invasive diagnostics of breast cancer that can be placed and visualized during ultrasonography, mammography, and magnetic resonance imaging. METHODS: The newly developed O-twist marker consists of three 0.15-mm biocompatible nitinol wires twisted together to form rings with a diameter of 2.5 mm. These are inserted elongated into a 20G cannula. The marker is ejected into the tissue through a mandrin and reverts to its predetermined ring form. RESULTS: The multiple curves of the surface render the marker highly visible. Its geometry permits secure anchorage even in larger biopsy cavities and additionally prevents migration within the tissue. CONCLUSION: The O-twist marker is applicable for all examination modalities and biopsy needles or biopsy systems and represents an important development for breast cancer diagnostics.

Breast Neoplasms↗

PubMed2005

[The quality of digital mammograms. Development and use of phantoms for optimal safety].

Digital imaging in mammography is becoming more and more accepted using both computed (CR) and direct radiography (DR). These techniques will soon be used in screening programs. Therefore, quality assurance for this technique is indispensable. The relevance of the current regulations, such as EPOC and the German QS-RL was investigated. For the investigation, a breast phantom and appropriate software were developed. Both were tested using digital mammography systems from six manufactures. Quality assurance parameters (such as contrast to noise ratio and contrast resolution) were calculated from these data sets. The results should be considered in future standards for mammography (IEC respectively DIN). In addition, this type of test procedure is time saving and enables a reduction in test devices, i. e. in costs.

Breast Neoplasms↗

PubMed2005

[3D ultrasound (3D US) in the diagnosis of focal breast lesions].

BACKGROUND: It was to analyse whether 3D breast US is able to enhance the diagnosis of focal breast lesions. MATERIAL AND METHODS: 60 patients were examined with 2D- and 3D US (GE logiq 9, 14 MHz). The solid lesions were analyzed by using the BIRADS classification. As standard of reference, histopathologic results were available in all cases. RESULTS: 38 malignant and 22 benign lesions were analyzed. With 2D US the sensitivity/specificity was 92/81%, with 3D US 97/72%, and by combination of 2D and 3D 97/81%. Characteristics of benign solid masses included a round or oval shape as well as clearly defined and sharply demarcated margins. CONCLUSIONS: 3D US allows to demonstrate breast masses in multiple planes. Distorsion of the surrounding soft tissues is an important sign indicative of malignancy.

Breast Neoplasms↗