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1.
In Vivo ; 37(2): 848-857, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36881047

RESUMEN

BACKGROUND/AIM: The objective of this study was to assess the perception of the forensic medical examination (FME) by victims of sexual violence. Based on patient-related outcomes gained in terms of personnel, chronological and spatial parameters, an additional aim was to derive improved examination procedures. PATIENTS AND METHODS: A total of 49 sexually assaulted women were enrolled in this study. After standardized FME by a forensic doctor followed by a gynecologist, women were asked to complete a questionnaire addressing general perception, preferences regarding attending staff's sex, sequence and time frame of the examinations performed. The attending gynecologist also completed a questionnaire addressing demographic and medical parameters of the patient as well as assault-related information. RESULTS: The examination setting in general was evaluated positively. Nevertheless, 52% of examined victims perceived the FME as an additional psychological burden. Overall, 85% of the affected women preferred a female forensic physician and 76% a female gynecologist to perform the examination. When women said they experienced a violation of their privacy during the gynecological examination, a male was more often present (60% vs. 35%, p=0.0866). Regarding the sequence of the examination components, 65% of the victims preferred to start with their medical history followed by the forensic and then the gynecological examination. CONCLUSION: Forensic medical and gynecological examination after sexual assault is an essential procedure, yet it is a potentially further traumatizing experience for the victim. The identified patient preferences should be taken into account in order to diminish further trauma.


Asunto(s)
Médicos , Delitos Sexuales , Femenino , Humanos , Masculino , Ginecólogos , Examen Físico
2.
Forensic Sci Med Pathol ; 17(4): 634-642, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34613594

RESUMEN

This study aimed to assess the validity and efficacy of blue dye in colposcopic assessment of genital injury in pre- and postmenopausal women with and without history of consensual sexual intercourse. Two hundred women were prospectively enrolled and examined colposcopically with and without toluidine blue dye in order to detect and categorize genital lesions (laceration, bruise and abrasion). Examination of genital trauma was accomplished in a standardized way and findings were photo documented. A wide range of influencing factors with a potential impact on prevalence and nature of genital injury was recorded beforehand using a questionnaire. The frequency of diagnostic injury differed substantially depending on the examination technique, ranging from 9% using colposcopic magnification only to 28% with the additional use of toluidine blue dye. A vertical laceration affecting the posterior fourchette was the most frequent lesion detected (17%, n = 32). Menopausal status seems to have significant impact on genital injury prevalence (p = 0.0165), as 42% (16/ 38) of postmenopausal compared to 24% (36/ 151) of premenopausal women had at least one genital lesion. Furthermore, vaginal medication (p = 0.0369), vaginal dryness (p = 0.0228), dyspareunia (p = 0.0234) and low frequency of sexual intercourse (p = 0.0022) were found to significantly correlate with the presence of genital lesions. According to our findings, standardized colposcopy in combination with toluidine blue dye facilitates accurate assessment of genital lesions. Genital trauma situated at another site than the posterior part of the vaginal introitus seems to be uncommon after consensual intercourse.


Asunto(s)
Colposcopía , Cloruro de Tolonio , Coito , Colorantes , Femenino , Genitales Femeninos , Humanos , Embarazo
3.
Forensic Sci Res ; 5(1): 74-84, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32490313

RESUMEN

Examination of a person who has been a victim of a physical or sexual assault may be very important for upcoming legal proceedings. In the context of a clinical forensic examination, physical findings are recorded and biological trace material is gathered and secured. Ideally, all forensic findings are documented in a detailed report combined with photographic documentation, which employs a forensic scale to depict the size of the injuries. However, the integrity of such forensic findings depends particularly on two factors. First, the examination needs to be conducted professionally to ensure that the findings are properly admissible as court evidence. Second, the examination should take place as soon as possible because the opportunity to successfully secure biological samples declines rapidly with time. Access to low-threshold clinical forensic examinations is not evenly provided in all member states of the European Union (EU); in some states, they are not available at all. As part of the JUSTeU! (Juridical standards for clinical forensic examinations of victims of violence in Europe) project, the Ludwig Boltzmann Institute for Clinical Forensic Imaging in Graz, Austria created (in cooperation with its international partner consortium) a questionnaire: the purpose was to collect information about support for victims of physical and/or sexual assault in obtaining a low-threshold clinical forensic examination in various countries of the EU. Our paper provides a summary of the responses and an overview of the current situation concerning provided clinical forensic services.

4.
Forensic Sci Int ; 287: 12-24, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29626838

RESUMEN

Three-dimensional (3D) crime scene documentation using 3D scanners and medical imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) are increasingly applied in forensic casework. Together with digital photography, these modalities enable comprehensive and non-invasive recording of forensically relevant information regarding injuries/pathologies inside the body and on its surface. Furthermore, it is possible to capture traces and items at crime scenes. Such digitally secured evidence has the potential to similarly increase case understanding by forensic experts and non-experts in court. Unlike photographs and 3D surface models, images from CT and MRI are not self-explanatory. Their interpretation and understanding requires radiological knowledge. Findings in tomography data must not only be revealed, but should also be jointly studied with all the 2D and 3D data available in order to clarify spatial interrelations and to optimally exploit the data at hand. This is technically challenging due to the heterogeneous data representations including volumetric data, polygonal 3D models, and images. This paper presents a novel computer-aided forensic toolbox providing tools to support the analysis, documentation, annotation, and illustration of forensic cases using heterogeneous digital data. Conjoint visualization of data from different modalities in their native form and efficient tools to visually extract and emphasize findings help experts to reveal unrecognized correlations and thereby enhance their case understanding. Moreover, the 3D case illustrations created for case analysis represent an efficient means to convey the insights gained from case analysis to forensic non-experts involved in court proceedings like jurists and laymen. The capability of the presented approach in the context of case analysis, its potential to speed up legal procedures and to ultimately enhance legal certainty is demonstrated by introducing a number of representative forensic cases.

5.
Eur J Gen Pract ; 24(1): 26-31, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-29168414

RESUMEN

BACKGROUND: The external post-mortem examination (EPME) is an important medical, legal and socio-economic task with far-reaching relevance; however, due to discrepancies between findings from EPMEs and actual cause of death, improvements in accuracy and quality are needed. OBJECTIVES: To investigate knowledge, competencies and attitudes regarding EPME in general practitioner (GP) post-graduate trainees. METHODS: Before four post-graduate training courses on the EPME for general practitioner trainees, organized in 2014 in the German federal state of Baden-Wuerttemberg, a questionnaire on the EPME was distributed by the lecturer, completed by the GP post-graduate trainees and returned to the lecturer. The questionnaire consisted of 19 items related to three main categories: knowledge, competencies and attitudes. RESULTS: Out of 380 GP post-graduate trainees, 128 completed and returned the questionnaire (response rate 33.7%). Less than 18% felt adequately confident in identifying a natural cause of death and less than 5% felt adequately confident in identifying an unnatural cause of death. Only 33% consistently fully uncover the corpse for the EPME. CONCLUSION: We found an important uncertainty in GP post-graduate trainees regarding their EPME knowledge and competencies.


Asunto(s)
Autopsia/métodos , Competencia Clínica , Educación de Postgrado en Medicina , Medicina General/educación , Adulto , Actitud del Personal de Salud , Causas de Muerte , Evaluación Educacional , Femenino , Médicos Generales/educación , Alemania , Conocimientos, Actitudes y Práctica en Salud , Humanos , Masculino , Estudiantes de Medicina , Encuestas y Cuestionarios
6.
Forensic Sci Med Pathol ; 13(2): 135-144, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28251480

RESUMEN

In legal medicine, reliable localization and analysis of hematomas in subcutaneous fatty tissue is required for forensic reconstruction. Due to the absence of ionizing radiation, magnetic resonance imaging (MRI) is particularly suited to examining living persons with forensically relevant injuries. However, there is limited experience regarding MRI signal properties of hemorrhage in soft tissue. The aim of this study was to evaluate MR sequences with respect to their ability to show high contrast between hematomas and subcutaneous fatty tissue as well as to reliably determine the volume of artificial hematomas. Porcine tissue models were prepared by injecting blood into the subcutaneous fatty tissue to create artificial hematomas. MR images were acquired at 3T and four blinded observers conducted manual segmentation of the hematomas. To assess segmentability, the agreement of measured volume with the known volume of injected blood was statistically analyzed. A physically motivated normalization taking into account partial volume effect was applied to the data to ensure comparable results among differently sized hematomas. The inversion recovery sequence exhibited the best segmentability rate, whereas the T1T2w turbo spin echo sequence showed the most accurate results regarding volume estimation. Both sequences led to reproducible volume estimations. This study demonstrates that MRI is a promising forensic tool to assess and visualize even very small amounts of blood in soft tissue. The presented results enable the improvement of protocols for detection and volume determination of hemorrhage in forensically relevant cases and also provide fundamental knowledge for future in-vivo examinations.


Asunto(s)
Hematoma/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Tejido Subcutáneo/diagnóstico por imagen , Animales , Patologia Forense , Hematoma/patología , Modelos Animales , Tejido Subcutáneo/patología , Porcinos
7.
Int J Legal Med ; 131(2): 489-496, 2017 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-27448110

RESUMEN

PURPOSE: The aim of this multi-reader feasibility study was to evaluate new post-processing CT imaging tools in rib fracture assessment of forensic cases by analyzing detection time and diagnostic accuracy. MATERIALS AND METHODS: Thirty autopsy cases (20 with and 10 without rib fractures in autopsy) were randomly selected and included in this study. All cases received a native whole body CT scan prior to the autopsy procedure, which included dissection and careful evaluation of each rib. In addition to standard transverse sections (modality A), CT images were subjected to a reconstruction algorithm to compute axial labelling of the ribs (modality B) as well as "unfolding" visualizations of the rib cage (modality C, "eagle tool"). Three radiologists with different clinical and forensic experience who were blinded to autopsy results evaluated all cases in a random manner of modality and case. RESULTS: Rib fracture assessment of each reader was evaluated compared to autopsy and a CT consensus read as radiologic reference. A detailed evaluation of relevant test parameters revealed a better accordance to the CT consensus read as to the autopsy. Modality C was the significantly quickest rib fracture detection modality despite slightly reduced statistic test parameters compared to modalities A and B. CONCLUSION: Modern CT post-processing software is able to shorten reading time and to increase sensitivity and specificity compared to standard autopsy alone. The eagle tool as an easy to use tool is suited for an initial rib fracture screening prior to autopsy and can therefore be beneficial for forensic pathologists.


Asunto(s)
Imagenología Tridimensional , Fracturas de las Costillas/diagnóstico por imagen , Tomografía Computarizada Espiral , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Estudios de Factibilidad , Humanos , Persona de Mediana Edad , Fracturas de las Costillas/patología , Programas Informáticos , Imagen de Cuerpo Entero , Adulto Joven
8.
Forensic Sci Int ; 266: 281-288, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27344264

RESUMEN

Determination of skeletal development is a key pillar in forensic age estimation of living persons. Radiological assessment of hand bone age is widely used until the age of about 17-18 years, applying visual grading techniques to hand radiographs. This study investigated whether Greulich-Pyle (GP) and Tanner-Whitehouse (TW2) grading can be equally used for magnetic resonance imaging (MRI) data, which would offer the huge benefit of avoiding ionizing radiation. In 18 subjects aged between 7 and 17 years a radiograph and an MRI scan of the hand were performed. Epiphyseal ossification of hand bones was rated by two blinded radiologists with both GP and TW2. Correlation between hand MRIs and radiographs was analyzed by linear regression and inter-observer agreement was assessed. Correlation between age estimates from MRI and radiographs was high for both GP (r(2)=0.98) and TW2 (r(2)=0.93). MRI showed a tendency to estimate age slightly lower for 14-18 year-olds, which would be favorable regarding majority age determination in case this result could be reproduced using a currently not existing reference estimation method based on MRI data. Inter-observer agreement was similar for GP in radiographs and MRI, while for TW2, agreement in MRI was lower than in radiographs. In spite of limitations regarding sample size and recruited subjects, our results indicate that the use of GP and TW2 on MRI data offers the possibility of hand bone age estimation without the need for ionizing radiation.


Asunto(s)
Determinación de la Edad por el Esqueleto/instrumentación , Determinación de la Edad por el Esqueleto/normas , Huesos de la Mano/diagnóstico por imagen , Imagen por Resonancia Magnética , Humanos , Proyectos Piloto
9.
Dtsch Med Wochenschr ; 140(15): 1148-52, 2015 Jul.
Artículo en Alemán | MEDLINE | ID: mdl-26230067

RESUMEN

In Germany the postmortem examination has to be performed by a physician. It has to include the determination of at least one sign of death, a statement about the time and cause of death and the distinction between a "death by natural causes" in the sense of the law and its opposite.


Asunto(s)
Autopsia/métodos , Accidentes/legislación & jurisprudencia , Causas de Muerte , Muerte , Certificado de Defunción , Alemania , Homicidio/legislación & jurisprudencia , Humanos , Cambios Post Mortem , Suicidio/legislación & jurisprudencia
11.
Int J Comput Assist Radiol Surg ; 10(5): 573-86, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25149272

RESUMEN

PURPOSE: During autopsy, forensic pathologists today mostly rely on visible indication, tactile perception and experience to determine the cause of death. Although computed tomography (CT) data is often available for the bodies under examination, these data are rarely used due to the lack of radiological workstations in the pathological suite. The data may prevent the forensic pathologist from damaging evidence by allowing him to associate, for example, external wounds to internal injuries. To facilitate this, we propose a new multimodal approach for intuitive visualization of forensic data and evaluate its feasibility. METHODS: A range camera is mounted on a tablet computer and positioned in a way such that the camera simultaneously captures depth and color information of the body. A server estimates the camera pose based on surface registration of CT and depth data to allow for augmented reality visualization of the internal anatomy directly on the tablet. Additionally, projection of color information onto the CT surface is implemented. RESULTS: We validated the system in a postmortem pilot study using fiducials attached to the skin for quantification of a mean target registration error of [Formula: see text] mm. CONCLUSIONS: The system is mobile, markerless, intuitive and real-time capable with sufficient accuracy. It can support the forensic pathologist during autopsy with augmented reality and textured surfaces. Furthermore, the system enables multimodal documentation for presentation in court. Despite its preliminary prototype status, it has high potential due to its low price and simplicity.


Asunto(s)
Autopsia/métodos , Medicina Legal , Tomografía Computarizada por Rayos X/métodos , Estudios de Factibilidad , Marcadores Fiduciales , Humanos , Proyectos Piloto , Programas Informáticos
12.
Int J Legal Med ; 129(2): 317-24, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25416961

RESUMEN

In clinical forensic medicine, hematomas and other externally visible injuries build the basis for the reconstruction of events. However, dating of subcutaneous hematomas based on their external aspect is difficult. Magnetic resonance imaging (MRI) has proven its use in dating intracranial hemorrhage. Thus, the aim was to investigate if MRI can also be used for dating subcutaneous hematomas and to analyze an eventual influence of the hematoma shape. In 20 healthy volunteers (11 females, 9 males, aged 26.9 ± 3.8 years), 4 ml of autologous blood were injected subcutaneously in the thigh. The hematoma was scanned immediately after the injection, after 3 and 24 h and 3, 7, and 14 days using three sequences with different contrast. Data was analyzed by measuring signal intensities of the hematoma, the muscle, and the subcutaneous tissue over time, and the Michelson contrast coefficients between the tissues were calculated. In the analysis, hematoma shape was considered. Signal intensity of blood in the proton density-weighted sequence reached its maximum 3 h after the injection with a subsequent decrease, whereas the signal intensities of muscle and fatty tissue remained constant. The time course of the Michelson coefficient of blood versus muscle decreased exponentially with a change from hyperintensity to hypointensity at 116.9 h, depending on hematoma shape. In the other sequences, either variability was large or contrast coefficients stayed constant over time. The observed change of contrast of blood versus muscle permits a quick estimate of a hematoma's age. The consideration of the hematoma shape is expected to further enhance dating using MRI.


Asunto(s)
Hematoma/patología , Imagen por Resonancia Magnética/métodos , Tejido Subcutáneo/patología , Adulto , Femenino , Patologia Forense , Humanos , Procesamiento de Imagen Asistido por Computador , Masculino , Músculo Esquelético/patología , Muslo , Factores de Tiempo
13.
Forensic Sci Int ; 241: 155-66, 2014 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-24952238

RESUMEN

The increasing use of CT/MR devices in forensic analysis motivates the need to present forensic findings from different sources in an intuitive reference visualization, with the aim of combining 3D volumetric images along with digital photographs of external findings into a 3D computer graphics model. This model allows a comprehensive presentation of forensic findings in court and enables comparative evaluation studies correlating data sources. The goal of this work was to investigate different methods to generate anonymous and patient-specific 3D models which may be used as reference visualizations. The issue of registering 3D volumetric as well as 2D photographic data to such 3D models is addressed to provide an intuitive context for injury documentation from arbitrary modalities. We present an image processing and visualization work-flow, discuss the major parts of this work-flow, compare the different investigated reference models, and show a number of cases studies that underline the suitability of the proposed work-flow for presenting forensically relevant information in 3D visualizations.


Asunto(s)
Simulación por Computador , Imagenología Tridimensional , Maniquíes , Femenino , Medicina Legal/métodos , Humanos , Lactante , Imagen por Resonancia Magnética , Masculino , Fotograbar , Programas Informáticos , Imagen de Cuerpo Entero , Adulto Joven
14.
Korean J Radiol ; 15(2): 205-9, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24644410

RESUMEN

A 63-year-old man was found in the street after overrun by a car. Postmortem CT revealed multiple bone fractures, but surprisingly all without any relevant hemorrhage which would have been expected under such circumstances. A round radiopaque formation was found in the duodenum, which was reminiscent of ingested tablets. The toxicological analysis revealed high concentrations of zopiclone and alcohol. By combining radiologic and forensic results, zopiclone and alcohol intoxication were concluded as the cause of death, followed by a postmortem overrun accident.


Asunto(s)
Intoxicación Alcohólica/diagnóstico , Compuestos de Azabiciclo/envenenamiento , Duodeno/diagnóstico por imagen , Hipnóticos y Sedantes/envenenamiento , Piperazinas/envenenamiento , Tomografía Computarizada por Rayos X/métodos , Accidentes de Tránsito , Compuestos de Azabiciclo/análisis , Resultado Fatal , Humanos , Hipnóticos y Sedantes/análisis , Masculino , Persona de Mediana Edad , Piperazinas/análisis
15.
J Trace Elem Med Biol ; 28(1): 1-7, 2014 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-24188895

RESUMEN

Recent brain research reveals a major role of trace elements in various diseases such as multiple sclerosis, Alzheimer's and Wilson's disease. The majority of published tissue concentrations dates back decades, and was assessed with various methods. Little is known about hemispherical differences, the correlation of trace elements or age-dependent changes in the human brain. Thus, the aim of this study was to examine trace element concentrations in different human brain regions after whole brain formalin fixation. 549 samples of 13 brain regions were investigated in 11 deceased subjects without known history of brain pathology. Regional wet-to-dry mass ratios and concentrations of iron, copper, magnesium, manganese, calcium and zinc were determined using inductively coupled plasma mass spectrometry. Cortical gray matter revealed higher water content (wet-to-dry mass ratios 5.84-6.40) than white matter regions (wet-to-dry mass ratios 2.95-3.05). Element concentrations displayed specific regional differences. Good linear correlation of concentrations between elements was found for iron/copper as well as for manganese/magnesium (Spearman's rank correlation coefficient 0.74 and 0.65, respectively). Significant inter-hemispherical differences were found for copper in occipital white matter, for magnesium and calcium in putamen and for iron and copper in temporal white matter. An age dependent increase was seen in cortical gray matter for calcium, for magnesium in all regions except in cortical gray matter, for copper in substantia nigra and for zinc in occipital cortex. The presented trace element concentrations can serve as a fundamental basis for further brain research. Wet-to-dry mass ratios allow a comparison with reference data from other studies.


Asunto(s)
Encéfalo/metabolismo , Espectrometría de Masas/métodos , Oligoelementos/análisis , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados
17.
Int J Legal Med ; 127(1): 195-200, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-22399104

RESUMEN

The purpose of this prospective study was to evaluate the rate of detection and correct classification of traumatic soft tissue injuries of the head using clinical multislice computed tomography (MSCT) compared with an external forensic examination. Thirty-one patients with soft tissue injuries after head trauma and clinically indicated cerebral MSCT scan underwent an external forensic examination with documentation of the morphological appearance and the exact localization of scalp and facial injuries. MSCT data were evaluated by a radiologist blinded to the results of the external examination using axial images as well as multiplanar reconstruction tools. The results of the radiological and forensic report were compared and analyzed. The main finding was that clinical MSCT data of the head detected 55 % of all external lesions and diagnosed the correct morphological type of lesion in 30 %. All lacerations and 44 % of the hematomas were correctly identified in the radiological report, whereas the diagnosis of swellings and abrasions was difficult. MSCT showed a high specificity for all types of soft tissue lesions. Additionally, a substantial number of internal lesions such as fractures or intracerebral bleedings were revealed which were not detected in the external examination. The results demonstrate that the forensic-radiologic evaluation of clinical MSCT data has a good diagnostic performance and is a valuable method to retrospectively supplement external forensic examination in living crime victims. It also might-to a certain extent-be used as the only source in cases where no forensic external examination has taken place within due time.


Asunto(s)
Tomografía Computarizada Multidetector , Cuero Cabelludo/diagnóstico por imagen , Cuero Cabelludo/lesiones , Adulto , Anciano , Anciano de 80 o más Años , Hemorragia Cerebral/diagnóstico por imagen , Hemorragia Cerebral/patología , Femenino , Patologia Forense , Fracturas Óseas/diagnóstico por imagen , Fracturas Óseas/patología , Hematoma/diagnóstico por imagen , Hematoma/patología , Humanos , Imagenología Tridimensional , Laceraciones/diagnóstico por imagen , Laceraciones/patología , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Cuero Cabelludo/patología , Sensibilidad y Especificidad , Adulto Joven
18.
Neuroimage ; 62(3): 1593-9, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22634862

RESUMEN

Quantitative susceptibility mapping (QSM) is a novel technique which allows determining the bulk magnetic susceptibility distribution of tissue in vivo from gradient echo magnetic resonance phase images. It is commonly assumed that paramagnetic iron is the predominant source of susceptibility variations in gray matter as many studies have reported a reasonable correlation of magnetic susceptibility with brain iron concentrations in vivo. Instead of performing direct comparisons, however, all these studies used the putative iron concentrations reported in the hallmark study by Hallgren and Sourander (1958) for their analysis. Consequently, the extent to which QSM can serve to reliably assess brain iron levels is not yet fully clear. To provide such information we investigated the relation between bulk tissue magnetic susceptibility and brain iron concentration in unfixed (in situ) post mortem brains of 13 subjects using MRI and inductively coupled plasma mass spectrometry. A strong linear correlation between chemically determined iron concentration and bulk magnetic susceptibility was found in gray matter structures (r=0.84, p<0.001), whereas the correlation coefficient was much lower in white matter (r=0.27, p<0.001). The slope of the overall linear correlation was consistent with theoretical considerations of the magnetism of ferritin supporting that most of the iron in the brain is bound to ferritin proteins. In conclusion, iron is the dominant source of magnetic susceptibility in deep gray matter and can be assessed with QSM. In white matter regions the estimation of iron concentrations by QSM is less accurate and more complex because the counteracting contribution from diamagnetic myelinated neuronal fibers confounds the interpretation.


Asunto(s)
Química Encefálica , Mapeo Encefálico/métodos , Hierro/análisis , Imagen por Resonancia Magnética/métodos , Adulto , Anciano , Anciano de 80 o más Años , Autopsia , Femenino , Humanos , Interpretación de Imagen Asistida por Computador , Masculino , Persona de Mediana Edad , Espectrofotometría Atómica
19.
Neuroimage ; 59(2): 1413-9, 2012 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-21893208

RESUMEN

MR phase images have shown significantly improved contrast between cortical gray and white matter regions compared to magnitude images obtained with gradient echo sequences. A variety of underlying biophysical mechanisms (including iron, blood, myelin content, macromolecular chemical exchange, and fiber orientation) have been suggested to account for this observation but assessing the individual contribution of these factors is limited in vivo. For a closer investigation of iron and myelin induced susceptibility changes, postmortem MRI of six human corpses (age range at death: 56-80 years) was acquired in situ. Following autopsy, the iron concentrations in the frontal and occipital cortex as well as in white matter regions were chemically determined. The magnetization transfer ratio (MTR) was used as an indirect measure for myelin content. Susceptibility effects were assessed separately by determining R2* relaxation rates and quantitative phase shifts. Contributions of myelin and iron to local variations of the susceptibility were assessed by univariate and multivariate linear regression analysis. Mean iron concentration was lower in the frontal cortex than in frontal white matter (26 ± 6 vs. 45 ± 6 mg/kg wet tissue) while an inverse relation was found in the occipital lobe (cortical gray matter: 41 ± 10 vs. white matter: 34 ± 10mg/kg wet tissue). Multiple regression analysis revealed iron and MTR as independent predictors of the effective transverse relaxation rate R2 but solely MTR was identified as source of MR phase contrast. R2 was correlated with iron concentrations in cortical gray matter only (r=0.42, p<0.05). In conclusion, MR phase contrast between cortical gray and white matter can be mainly attributed to variations in myelin content, but not to iron concentration. Both, myelin and iron impact the effective transverse relaxation rate R2 significantly. Magnitude contrast is limited because it only reflects the extent but not the direction of the susceptibility shift.


Asunto(s)
Química Encefálica , Hierro/química , Imagen por Resonancia Magnética/métodos , Vaina de Mielina/química , Fibras Nerviosas Mielínicas/química , Neuronas/química , Anciano de 80 o más Años , Encéfalo/citología , Cadáver , Humanos , Hierro/análisis , Masculino , Fibras Nerviosas Mielínicas/ultraestructura , Neuronas/citología
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