Contrast-enhanced 3-D MRA in decision making for carotid endarterectomy: a 6-year experience

BACKGROUND: Systematic need for angiography in diagnosis of carotid artery stenosis and indication of surgical therapy is still debated. Noninvasive imaging techniques such as MR angiography (MRA) or CT angiography (CTA) offer an alternative to digital subtraction angiography (DSA) and are increasingly used in clinical practice. In this study, we present the radiological characteristics and clinical results of a series of patients operated on the basis of combined ultrasonography (US)/MRA. METHODS: This observational study included all the patients consecutively operated for a carotid stenosis in our Department from October 1998 to December 2004. The applied MRA protocol had previously been established in a large correlation study with DSA. DSA was used only in case of discordance between US and MRA. The preoperative radiological information furnished by MRA was compared with intraoperative findings. The outcome of the operation was assessed according to ECST criteria. RESULTS: Among 327 patients, preoperative MRA was performed in 278 (85%), DSA in 44 (13.5%) and CT angiography in 5 (1.5%). Most of DSA studies were performed as emergency for preparation of endovascular therapy or for reasons other than carotid stenosis. Eleven additional DSA (3.3%) complemented US/MRA, mostly because diverging diagnosis of subocclusion of ICA. No direct morbidity or intraoperative difficulty was related to preoperative MRA. Combined mortality/major morbidity rate was 0.9% (3 patients) and minor morbidity rate 5.5% (18 patients). CONCLUSIONS: This observational study describes a well-established practice of carotid surgery and supports the exclusive use of non invasive diagnostic imaging for indicating and deciding the operation.

Examining the gateway to the limbic system with diffusion tensor imaging: the perforant pathway in dementia

Current treatments for Alzheimer's disease (AD) are only able to slow the progression of mental deterioration, making early and reliable diagnosis an essential part of any promising therapeutic strategy. In the initial stages of AD, the first neuropathological alterations occur in the perforant pathway (PP), a large neuronal fiber tract located at the entrance to the limbic system. However, to date, there is no sensitive diagnostic tool for performing in vivo assessments of this structure. In the present bimodal magnetic resonance imaging (MRI) study, we examined 10 elderly controls, 10 subjects suffering from mild cognitive impairment (MCI), and 10 AD patients in order to evaluate the sensitivity of diffusion tensor imaging (DTI), a new MRI technique, for detecting changes in the PP. Furthermore, the diagnostic explanatory power of DTI data of the PP should be compared to high-resolution MRI volumetry and intervoxel coherences (COH) of the hippocampus and the entorhinal cortex, two limbic regions also involved in the pathophysiology of early AD. DTI revealed a marked decrease in COH values in the PP region of MCI (right side: 26%, left side: 29%, as compared to controls) and AD patients (right side: 37%, left side: 43%, as compared to controls). Reductions in COH values of the PP region were significantly correlated with cognitive impairment. DTI data of the PP zone were the only parameter differing significantly between control subjects and MCI patients, while the volumetric measures and the COH values of the hippocampus and the entorhinal cortex did not. DTI of medial temporal brain regions is a promising non-invasive tool for the in vivo diagnosis of the early/preclinical stages of AD.

Influence of water immersion, water gymnastics and swimming on cardiac output in patients with heart failure

Background Whole-body water immersion leads to a significant shift of blood from the periphery into the intra-thoracic circulation, followed by an increase in central venous pressure and heart volume. In patients with severely reduced left ventricular function, this hydrostatically in-duced volume shift might overstrain the cardiovascular adaptive mechanisms and lead to cardiac decompensation. The aim of this study is to assess the hemodynamic response to water immer-sion, gymnastics and swimming in patients with heart failure (CHF). Methods We examined 10 patients with compensated CHF (62.9 +/- 6.3 years, EF 31.5 +/- 4.1%, peak VO2 19.4 +/- 2.8 ml/kg/min.), 10 patients with coronary artery disease (CAD) but preserved left ventricular function (57.2 +/- 5.6 years, EF 63.9 +/- 5.5%, peak VO2 28.0 +/- 6.3 ml/kg/min.) and 10 healthy subjects (32.8 +/- 7.2 years, peak VO2 45.6 +/- 6.0 ml/kg/min.). Hemodynamic response to thermo-neutral (32 degrees C) water immersion and exercise was measured using a non-invasive foreign gas rebreathing method during stepwise water immersion, water gymnastics and swimming. Results Water immersion up to the chest increased cardiac index by 19% in healthy subjects, by 21% in CAD patients and 16% in CHF patients. While some CHF patients showed a decrease of stroke volume during immersion, all subjects were able to increase cardiac index (by 87% in healthy subjects, 77% in CAD patients and 53% in CHF patients). Oxygen uptake during swim-ming was 9.7 +/- 3.3 ml/kg/min. in CHF patients, 12.4 +/- 3.5 ml/kg/min. in CAD patients and 13.9 +/- 4.0 ml/kg/min. in healthy subjects. Conclusions Patients with severely reduced left ventricular function but stable clinical conditions and a minimal peak VO2 of at least 15 ml/kg/min. during a symptom-limited exercise stress test tolerate water immersion and swimming in thermo-neutral water well. Although cardiac in-dex and oxygen uptake are lower compared with CAD patients with preserved left ventricular function and healthy controls, these patients are able to increase cardiac index adequately during water immersion and swimming.

Post-mortem tissue sampling using computed tomography guidance

PURPOSE: Currently, in forensic medicine cross-sectional imaging gains recognition and a wide use as a non-invasive examination approach. Today, computed tomography (CT) or magnetic resonance imaging that are available for patients are unable to provide tissue information on the cellular level in a non-invasive manner and also diatom detection, DNA, bacteriological, chemical toxicological and other specific tissue analyses are impossible using radiology. We hypothesised that post-mortem minimally invasive tissue sampling using needle biopsies under CT guidance might significantly enhance the potential of virtual autopsy. The purpose of this study was to test the use of a clinically approved biopsy needle for minimally invasive post-mortem sampling of tissue specimens under CT guidance. MATERIAL AND METHODS: ACN III biopsy core needles 14 gauge x 160 mm with automatic pistol device were used on three bodies dedicated to research from the local anatomical institute. Tissue probes from the brain, heart, lung, liver, spleen, kidney and muscle tissue were obtained under CT fluoroscopy. RESULTS: CT fluoroscopy enabled accurate placement of the needle within the organs and tissues. The needles allowed for sampling of tissue probes with a mean width of 1.7 mm (range 1.2-2 mm) and the maximal length of 20 mm at all locations. The obtained tissue specimens were of sufficient size and adequate quality for histological analysis. CONCLUSION: Our results indicate that, similar to the clinical experience but in many more organs, the tissue specimens obtained using the clinically approved biopsy needle are of a sufficient size and adequate quality for a histological examination. We suggest that post-mortem biopsy using the ACN III needle under CT guidance may become a reliable method for targeted sampling of tissue probes of the body.

Role of proton MR for the study of muscle lipid metabolism

1H-MR spectroscopy (MRS) of intramyocellular lipids (IMCL) became particularly important when it was recognized that IMCL levels are related to insulin sensitivity. While this relation is rather complex and depends on the training status of the subjects, various other influences such as exercise and diet also influence IMCL concentrations. This may open insight into many metabolic interactions; however, it also requires careful planning of studies in order to control all these confounding influences. This review summarizes various historical, methodological, and practical aspects of 1H-MR spectroscopy (MRS) of muscular lipids. That includes a differentiation of bulk magnetic susceptibility effects and residual dipolar coupling that can both be observed in MRS of skeletal muscle, yet affecting different metabolites in a specific way. Fitting of the intra- (IMCL) and extramyocellular (EMCL) signals with complex line shapes and the transformation into absolute concentrations is discussed. Since the determination of IMCL in muscle groups with oblique fiber orientation or in obese subjects is still difficult, potential improvement with high-resolution spectroscopic imaging or at higher field strength is considered. Fat selective imaging is presented as a possible alternative to MRS and the potential of multinuclear MRS is discussed. 1H-MRS of muscle lipids allows non-invasive and repeated studies of muscle metabolism that lead to highly relevant findings in clinics and patho-physiology.

Noninvasive monitoring of chest wall movement in infants using laser

Traditionally, non-invasive monitoring of tidal volume in infants has been performed using impedance plethysmography analyzed using a one or two compartment model. We developed a new laser system for use in infants, which measures antero-posterior movement of the chest wall during quiet sleep. In 24 unsedated or sedated infants (11 healthy, 13 with respiratory disease), we examined whether the analysis of thoracoabdominal movement based on a three compartment model could more accurately estimate tidal volume in comparison to V(T) measured at the mouth. Using five laser signals, chest wall movements were measured at the right and left, upper and lower ribcage and the abdomen. Within the tidal volume range from 4.6 to 135.7 ml, a three compartment model showed good short term repeatability and the best agreement with tidal volume measured at mouth (r(2) = 0.86) compared to that of a single compartment model (r(2) = 0.62, P < 0.0001) and a two compartment model (r(2) = 0.82, P < 0.01), particularly in the presence of respiratory disease. Three compartment modeling of a 5 laser thoracoabdominal monitoring permits more accurate estimates of tidal volume in infants and potentially of regional differences of chest wall displacement in future studies.

Assessment of spline-based 2D-3D registration for image-guided spine surgery

2D-3D registration of pre-operative 3D volumetric data with a series of calibrated and undistorted intra-operative 2D projection images has shown great potential in CT-based surgical navigation because it obviates the invasive procedure of the conventional registration methods. In this study, a recently introduced spline-based multi-resolution 2D-3D image registration algorithm has been adapted together with a novel least-squares normalized pattern intensity (LSNPI) similarity measure for image guided minimally invasive spine surgery. A phantom and a cadaver together with their respective ground truths were specially designed to experimentally assess possible factors that may affect the robustness, accuracy, or efficiency of the registration. Our experiments have shown that it is feasible for the assessed 2D-3D registration algorithm to achieve sub-millimeter accuracy in a realistic setup in less than one minute.

How can we measure the impact of pollutants on respiratory function in very young children? Methodological aspects

There is increasing evidence that air pollution particularly affects infants and small preschool children. However, detecting air pollution effects on lung function in small children is technically difficult and requires non-invasive methods that can assess lung function and inflammatory markers in larger cohorts. This review discusses the principles, usefulness and shortcomings of various lung function techniques used to detect pollution effects in small children. The majority of these techniques have been used to detect effects of the dominant indoor pollutant, tobacco exposure. However there is increasing evidence that non-invasive lung function techniques can also detect the effects of outdoor air pollution.

Virtopsy - the concept of a centralized database in forensic medicine for analysis and comparison of radiological and autopsy data

Recent developments in clinical radiology have resulted in additional developments in the field of forensic radiology. After implementation of cross-sectional radiology and optical surface documentation in forensic medicine, difficulties in the validation and analysis of the acquired data was experienced. To address this problem and for the comparison of autopsy and radiological data a centralized database with internet technology for forensic cases was created. The main goals of the database are (1) creation of a digital and standardized documentation tool for forensic-radiological and pathological findings; (2) establishing a basis for validation of forensic cross-sectional radiology as a non-invasive examination method in forensic medicine that means comparing and evaluating the radiological and autopsy data and analyzing the accuracy of such data; and (3) providing a conduit for continuing research and education in forensic medicine. Considering the infrequent availability of CT or MRI for forensic institutions and the heterogeneous nature of case material in forensic medicine an evaluation of benefits and limitations of cross-sectional imaging concerning certain forensic features by a single institution may be of limited value. A centralized database permitting international forensic and cross disciplinary collaborations may provide important support for forensic-radiological casework and research.

ECG-triggered muscular counterpulsation for treatment of low cardiac output

BACKGROUND: Skeletal muscular counterpulsation (MCP) has been used as a new noninvasive technique for treatment of low cardiac output. The MCP method is based on ECG-triggered skeletal muscle stimulation. The purpose of the present study was to evaluate acute hemodynamic changes induced by MCP in the experimental animal. METHODS: Eight anaesthetized pigs (43+/-4 kg) were studied at rest and after IV â-blockade (10 mg propranolol) before and after MCP. Muscular counterpulsation was performed on both thighs using trains (75 ms duration) of multiple biphasic electrical impulses with a width of 1 ms and a frequency of 200 Hz at low (10 V) and high (30 V) amplitude. ECG-triggering was used to synchronize stimulation to a given time point. LV pressure-volume relations were determined using the conductance catheter. After baseline measurements, MCP was carried out for 10 minutes at low and high stimulation amplitude. The optimal time point for MCP was determined from LV pressure-volume loops using different stimulation time points during systole and diastole. Best results were observed during end-systole and, therefore, this time point was used for stimulation. RESULTS: Under control conditions, MCP was associated with a significant decrease in pulmonary vascular resistance (-18%), a decrease in systemic vascular resistance (-11%) and stroke work index (-4%), whereas cardiac index (+2%) and ejection fraction (+6%) increased slightly. Pressure-volume loops showed a leftward shift with a decrease in end-systolic volume. After â-blockade, cardiac function decreased (HR, MAP, EF, dP/dt max), but it improved with skeletal muscle stimulation (HR +10% and CI +17%, EF +5%). There was a significant decrease in pulmonary (-19%) and systemic vascular resistance (-29%). CONCLUSIONS: In the animal model, ECG-triggered skeletal muscular counterpulsation is associated with a significant improvement in cardiac function at baseline and after IV â-blockade. Thus, MCP represents a new, non-invasive technique which improves cardiac function by diastolic compression of the peripheral arteries and veins, with a decrease in systemic vascular resistance and increase in cardiac output.

Cerebral connectivity and psychotic personality traits : A diffusion tensor imaging study

This study aims to investigate the relationship between regional connectivity in the brain white matter and the presence of psychotic personality traits, in healthy subjects with psychotic traits. Thirteen healthy controls were administered the MMPI-2, to assess psychotic traits and, according to MMPI results, a dichotomization into a group of "high-psychotic" and "low-psychotic" was performed. Diffusion tensor imaging (DTI) was used as a non-invasive measure, in order to obtain information about the fractional anisotropy (FA), an intravoxel index of local connectivity and, by means of a voxelwise approach, the between-group differences of the FA values were calculated. The "high-psychotic" group showed higher FA in the left arcuate fasciculus. Subjects with low scores for psychotic traits had significantly higher FA in the corpus callosum, right arcuate fasciculus, and fronto-parietal fibers. In line with previous brain imaging studies of schizophrenia spectrum disorders, our results suggest that psychotic personality traits are related to altered connectivity and brain asymmetry.

Matrix metalloproteinase-19 is a predictive marker for tumor invasiveness in patients with oropharyngeal squamous cell carcinoma

AIMS: To evaluate the expression of matrix metalloproteinase-19 (MMP-19) in oropharyngeal squamous cell carcinoma along with its association with structural features of invasiveness. To investigate whether MMP-19 expression correlates with lymphatic or systemic metastasis and prognosis in patients who have received definitive radiotherapy. METHODS AND RESULTS: The histological evaluation of the invasive front was based on Bryne's malignancy grading system. We correlated the immunohistochemical expression pattern with morphological parameters which characterize tumor invasiveness such as keratinization, nuclear polymorphism, invasion pattern, and the host inflammatory response. Local immunoreactivity for MMP-19 was positively correlated with tumor invasiveness as reflected in its structural characteristics and the degree of nuclear polymorphism, and negatively correlated with the inflammatory response of the host. No correlation existed between MMP-19 expression and clinicopathological features (TNM stage, grade of differentiation) or a patient''s outcome and prognosis. CONCLUSIONS: This latter finding probably reflects the unique change for MMPs from high immunoreactivity within healthy tissue areas and non-invasive tumor parts, through absence in the least invasive neoplastic regions, to strong re-expression at a highly invasive front of the same tumor. Our findings indicate that MMP-19 can be used as a marker for tumor invasiveness in patients with oropharyngeal squamous cell carcinoma.

Virtual autopsy using imaging: bridging radiologic and forensic sciences. A review of the Virtopsy and similar projects

The transdisciplinary research project Virtopsy is dedicated to implementing modern imaging techniques into forensic medicine and pathology in order to augment current examination techniques or even to offer alternative methods. Our project relies on three pillars: three-dimensional (3D) surface scanning for the documentation of body surfaces, and both multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) to visualise the internal body. Three-dimensional surface scanning has delivered remarkable results in the past in the 3D documentation of patterned injuries and of objects of forensic interest as well as whole crime scenes. Imaging of the interior of corpses is performed using MSCT and/or MRI. MRI, in addition, is also well suited to the examination of surviving victims of assault, especially choking, and helps visualise internal injuries not seen at external examination of the victim. Apart from the accuracy and three-dimensionality that conventional documentations lack, these techniques allow for the re-examination of the corpse and the crime scene even decades later, after burial of the corpse and liberation of the crime scene. We believe that this virtual, non-invasive or minimally invasive approach will improve forensic medicine in the near future.

Indocyanine green plasma disappearance rate during the anhepatic phase of orthotopic liver transplantation

Non-invasive pulse spectrophotometry to measure indocyanine green (ICG) elimination correlates well with the conventional invasive ICG clearance test. Nevertheless, the precision of this method remains unclear for any application, including small-for-size liver remnants. We therefore measured ICG plasma disappearance rate (PDR) during the anhepatic phase of orthotopic liver transplantation using pulse spectrophotometry. Measurements were done in 24 patients. The median PDR after exclusion of two outliers and two patients with inconstant signal was 1.55%/min (95% confidence interval [CI]=0.8-2.2). No correlation with patient age, gender, body mass, blood loss, administration of fresh frozen plasma, norepinephrine dose, postoperative albumin (serum), or difference in pre and post transplant body weight was detected. In conclusion, we found an ICG-PDR different from zero in the anhepatic phase, an overestimation that may arise in particular from a redistribution into the interstitial space. If ICG pulse spectrophotometry is used to measure functional hepatic reserve, the verified average difference from zero (1.55%/min) determined in our study needs to be taken into account.

Abdominal magnetic resonance imaging in small rodents using a clinical 1.5 T MR scanner

Because of superior soft-tissue contrast compared to other imaging techniques, non-invasive abdominal magnetic resonance imaging (MRI) is ideal for monitoring organ regeneration, tissue repair, cancer stage, and treatment effects in a wide variety of experimental animal models. Currently, sophisticated MR protocols, including technically demanding procedures for motion artefact compensation, achieve an MRI resolution limit of < 100 microm under ideal conditions. However, such a high spatial resolution is not required for most experimental rodent studies. This article describes both a detailed imaging protocol for MR data acquisition in a ubiquitously and commercially available 1.5 T MR unit and 3-dimensional volumetry of organs, tissue components, or tumors. Future developments in MR technology will allow in vivo investigation of physiological and pathological processes at the cellular and even the molecular levels. Experimental MRI is crucial for non-invasive monitoring of a broad range of biological processes and will further our general understanding of physiology and disease.