Virtopsy: forensic traumatology of the subcutaneous fatty tissue; multislice computed tomography (MSCT) and magnetic resonance imaging (MRI) as diagnostic tools

Traumatic lesions of the subcutaneous fatty tissue provide important clues for forensic reconstruction. The interpretation of these patterns requires a precise description and recording of the position and extent of each lesion. During conventional autopsy, this evaluation is performed by dissecting the skin and subcutaneous tissues in successive layers. In this way, depending on the force and type of impact (right angle or tangent), several morphologically distinct stages of fatty tissue damage can be differentiated: perilobular hemorrhage (I), contusion (II), or disintegration (III) of the fat lobuli, and disintegration with development of a subcutaneous cavity (IV). In examples of virtopsy cases showing blunt trauma to the skin and fatty tissue, we analyzed whether these lesions can also be recorded and classified using multislice computed tomography (MSCT) and magnetic resonance imaging (MRI). MSCT has proven to be a valuable screening method to detect the lesions, but MRI is necessary in order to properly differentiate and classify the grade of damage. These noninvasive radiological diagnostic tools can be further developed to play an important role in forensic examinations, in particular when it comes to evaluating living trauma victims.

Dynamic contrast-enhanced and diffusion-weighted MRI for early detection of tumoral changes in single-dose and fractionated radiotherapy: evaluation in a rat rhabdomyosarcoma model

We aimed to examine different intratumoral changes after single-dose and fractionated radiotherapy, using diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI in a rat rhabdomyosarcoma model. Four WAG/Rij rats with rhabdomyosarcomas in the flanks received single-dose radiotherapy of 8 Gy, and four others underwent fractionated radiotherapy (five times 3 Gy). In rats receiving single-dose radiotherapy, a significant perfusion decrease was found in the first 2 days post-treatment, with slow recuperation afterwards. No substantial diffusion changes could be seen; tumor growth delay was 12 days. The rats undergoing fractionated radiotherapy showed a similar perfusion decrease early after the treatment. However, a very strong increase in apparent diffusion coefficient occurred in the first 10 days; growth delay was 18 days. DW-MRI and DCE-MRI can be used to show early tumoral changes induced by radiotherapy. Single-dose and fractionated radiotherapy induce an immediate perfusion effect, while the latter induces more intratumoral necrosis.

Far lateral lumbar disc extrusion: MRI findings and surgical treatment

This case report describes the magnetic resonance imaging (MRI) findings and the treatment of a far lateral extrusion of disc material at the sixth and seventh lumbar vertebrae (L6-L7) in a five-year-old male Alpine Dachsbracke dog referred to our hospital for investigation of the complaint of a one week progressive lameness in the left pelvic limb and poorly localized back pain. An extra-foraminal left lateral disc herniation impinging on the sixth lumbar nerve root was diagnosed by MRI examinations. Due to the far lateral position of the extruded disc material on MRI, surgical opening of the spinal canal was not necessary. Removal of the herniated soft disc material impinging on the L6 nerve root, and fenestration of the L6-L7 disc was performed laterally. To the author's knowledge 'far-lateral' disc herniation beyond the neuroforamen without any spinal canal contact has not been described in dogs until now. A complete recovery with no evidence of pain was achieved only after a couple of weeks after surgery. We acknowledge that it is possible that other pathological mechanisms may have contributed to clinical signs and to a delayed recovery.

Prevalence of cam and pincer-type deformities on hip MRI in an asymptomatic young Swiss female population: a cross-sectional study

OBJECTIVES Femoroacetabular impingement is proposed to cause early osteoarthritis (OA) in the non-dysplastic hip. We previously reported on the prevalence of femoral deformities in a young asymptomatic male population. The aim of this study was to determine the prevalence of both femoral and acetabular types of impingement in young females. METHODS We conducted a population-based cross-sectional study of asymptomatic young females. All participants completed a set of questionnaires and underwent clinical examination of the hip. A random sample was subsequently invited to obtain magnetic resonance images (MRI) of the hip. All MRIs were read for cam-type deformities, increased acetabular depths, labral lesions, and impingement pits. Prevalence estimates of cam-type deformities and increased acetabular depths were estimated, and relationships between deformities and signs of joint damage were examined using logistic regression models. RESULTS The study included 283 subjects, and 80 asymptomatic females with a mean age of 19.3 years attended MRI. Fifteen showed some evidence of cam-type deformities, but none were scored to be definite. The overall prevalence was therefore 0% [95% confidence interval (95% CI) 0-5%]. The prevalence of increased acetabular depth was 10% (95% CI 5-19). No association was found between increased acetabular depth and decreased internal rotation of the hip. Increased acetabular depth was not associated with signs of labral damage. CONCLUSIONS Definite cam-type deformities in women are rare compared to men, whereas the prevalence of increased acetabular depth is higher, suggesting that femoroacetabular impingement has different gender-related biomechanical mechanisms.

Effect of dark chocolate on renal tissue oxygenation as measured by BOLD-MRI in healthy volunteers

BACKGROUND Cocoa is rich in flavonoids, has anti-oxidative properties and increases the bioavailability of nitric oxide (NO). Adequate renal tissue oxygenation is crucial for the maintenance of renal function. The goal of this study was to investigate the effect of cocoa-rich dark chocolate (DC) on renal tissue oxygenation in humans, as compared to flavonoid-poor white chocolate (WC). METHODS Ten healthy volunteers with preserved kidney function (mean age ± SD 35 ± 12 years, 70% women, BMI 21 ± 3 kg/m2) underwent blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) before and 2 hours after the ingestion of 1 g/kg of DC (70% cocoa). Renal tissue oxygenation was determined by the measurement of R2* maps on 4 coronal slices covering both kidneys. The mean R2* (= 1/T2*) values in the medulla and cortex were calculated, a low R2* indicating high tissue oxygenation. Eight participants also underwent BOLD-MRI at least 1 week later, before and 2 hours after the intake of 1 g/kg WC. RESULTS The mean medullary R2* was lower after DC intake compared to baseline (28.2 ± 1.3 s-1 vs. 29.6 ± 1.3 s-1, p = 0.04), whereas cortical and medullary R2* values did not change after WC intake. The change in medullary R2* correlated with the level of circulating (epi)catechines, metabolites of flavonoids (r = 0.74, p = 0.037), and was independent of plasma renin activity. CONCLUSION This study suggests for the first time an increase of renal medullary oxygenation after intake of dark chocolate. Whether this is linked to flavonoid-induced changes in renal perfusion or oxygen consumption, and whether cocoa has potentially renoprotective properties, merits further study.

Electrophysiological properties of mouse and epitope-tagged human cardiac sodium channel Na v1.5 expressed in HEK293 cells

Background: The pore-forming subunit of the cardiac sodium channel, Na v1.5, has been previously found to be mutated in genetically determined arrhythmias. Na v1.5 associates with many proteins that regulate its function and cellular localisation. In order to identify more in situ Na v1.5 interacting proteins, genetically-modified mice with a high-affinity epitope in the sequence of Na v1.5 can be generated. Methods: In this short study, we (1) compared the biophysical properties of the sodium current (I Na) generated by the mouse Na v1.5 (mNa v1.5) and human Na v1.5 (hNa v1.5) constructs that were expressed in HEK293 cells, and (2) investigated the possible alterations of the biophysical properties of the human Na v1.5 construct that was modified with specific epitopes. Results: The biophysical properties of mNa v1.5 were similar to the human homolog. Addition of epitopes either up-stream of the N-terminus of hNa v1.5 or in the extracellular loop between the S5 and S6 transmembrane segments of domain 1, significantly decreased the amount of I Na and slightly altered its biophysical properties. Adding green fluorescent protein (GFP) to the N-terminus did not modify any of the measured biophysical properties of hNa v1.5. Conclusions: These findings have to be taken into account when planning to generate genetically-modified mouse models that harbour specific epitopes in the gene encoding mNa v1.5.

Does normalized signal intensity of cervical discs on T2 weighted MRI images change in whiplash patients?

PURPOSE We tested the hypothesis that whiplash trauma leads to changes of the signal intensity of cervical discs in T2-weighted images. METHODS AND MATERIALS 50 whiplash patients (18-65 years) were examined within 48h after motor vehicle accident, and again after 3 and 6 months and compared to 50 age- and sex-matched controls. Signal intensity in ROI's of the discs at the levels C2/3 to C7/T1 and the adjacent vertebral bodies were measured on sagittal T2 weighted MR images and normalized using the average of ROI's in fat tissue. The contrast between discs and both adjacent vertebrae was calculated and disc degeneration was graded by the Pfirrmann-grading system. RESULTS Whiplash trauma did not have a significant effect on the normalized signals from discs and vertebrae, on the contrast between discs and adjacent vertebrae, or on the Pfirrmann grading. However, the contrast between discs and adjacent vertebrae and the Pfirrmann grading showed a strong correlation. In healthy volunteers, the contrast between discs and adjacent vertebrae and Pfirrmann grading increased with age and was dependent on the disc level. CONCLUSION We could not find any trauma related changes of cervical disc signal intensities. Normalized signals of discs and Pfirrmann grading changed with age and varied between disc levels with the used MR sequence.

Pulmonary thromboembolism as cause of death on unenhanced postmortem 3T MRI

OBJECTIVES: To investigate unenhanced postmortem 3-T MR imaging (pmMRI) for the detection of pulmonary thrombembolism (PTE) as cause of death. METHODS: In eight forensic cases dying from a possible cardiac cause but with homogeneous myocardium at cardiac pmMRI, additional T2w imaging of the pulmonary artery was performed before forensic autopsy. Imaging was carried out on a 3-T MR system in the axial and main pulmonary artery adapted oblique orientation in situ. In three cases axial T2w pmMRI of the lower legs was added. Validation of imaging findings was performed during forensic autopsy. RESULTS: All eight cases showed homogeneous material of intermediate signal intensity within the main pulmonary artery and/or pulmonary artery branches. Autopsy confirmed the MR findings as pulmonary artery thrombembolism. At lower leg imaging unilateral dilated veins and subcutaneous oedema with or without homogeneous material of intermediate signal intensity within the popliteal vein were found. CONCLUSIONS: Unenhanced pmMRI demonstrates pulmonary thrombembolism in situ. PmMR may serve as an alternative to clinical autopsy, especially when consent cannot be obtained. KEY POINTS: • Postmortem MRI (pmMRI) provides an alternative to clinical autopsy • Fatal pulmonary thrombembolism (PTE) can now be diagnosed using postmortem MRI (pmMRI). • Special attention has to be drawn to the differentiation of postmortem clots.