L'magerie forensique [Forensic imaging].

In recent years, modern techniques of medical imaging such as MDCT (multidetector-computed tomography) and MRI (magnetic resonance imaging) have pioneered post mortem (pm) investigations, especially in forensic medicine. Particularly pm angiography permits investigating the vascular system in a way which is not possible by performing only conventional autopsy. Beside these radiological methods, other modem visualizing techniques like the three dimensional (3D) surface scan have been implemented in order perform reconstructions of complex cases. By the use of pm imaging techniques, more objective and accurate documentations can be realized that permit an increase of quality in forensic investigations.

Prognostic accuracy of cerebral blood flow measurement by perfusion computed tomography, at the time of emergency room admission, in acute stroke patients.

The purpose of this study was to determine the prognostic accuracy of perfusion computed tomography (CT), performed at the time of emergency room admission, in acute stroke patients. Accuracy was determined by comparison of perfusion CT with delayed magnetic resonance (MR) and by monitoring the evolution of each patient's clinical condition. Twenty-two acute stroke patients underwent perfusion CT covering four contiguous 10mm slices on admission, as well as delayed MR, performed after a median interval of 3 days after emergency room admission. Eight were treated with thrombolytic agents. Infarct size on the admission perfusion CT was compared with that on the delayed diffusion-weighted (DWI)-MR, chosen as the gold standard. Delayed magnetic resonance angiography and perfusion-weighted MR were used to detect recanalization. A potential recuperation ratio, defined as PRR = penumbra size/(penumbra size + infarct size) on the admission perfusion CT, was compared with the evolution in each patient's clinical condition, defined by the National Institutes of Health Stroke Scale (NIHSS). In the 8 cases with arterial recanalization, the size of the cerebral infarct on the delayed DWI-MR was larger than or equal to that of the infarct on the admission perfusion CT, but smaller than or equal to that of the ischemic lesion on the admission perfusion CT; and the observed improvement in the NIHSS correlated with the PRR (correlation coefficient = 0.833). In the 14 cases with persistent arterial occlusion, infarct size on the delayed DWI-MR correlated with ischemic lesion size on the admission perfusion CT (r = 0.958). In all 22 patients, the admission NIHSS correlated with the size of the ischemic area on the admission perfusion CT (r = 0.627). Based on these findings, we conclude that perfusion CT allows the accurate prediction of the final infarct size and the evaluation of clinical prognosis for acute stroke patients at the time of emergency evaluation. It may also provide information about the extent of the penumbra. Perfusion CT could therefore be a valuable tool in the early management of acute stroke patients.

Abdominal Angiostrongylosis in Southern Brazil - Prevalence and Parasitic Burden in Mollusc Intermediate Hosts from Eighteen Endemic Foci

Angiostrongylus costaricensis is a parasitic nematode of rodents and molluscs are the intermediate hosts. Nocturnal collection of molluscs and search for infective third stage larvae of A. costaricensis was carried out in 18 endemic foci identified by the notification of a confirmed diagnosis in human biopsies or surgical specimens. Molluscs were digested in acidic solution and isolation of larvae eventually present was done in a Baermann funnel. Larvae identified by the presence of a delicate groove in the tail were counted to assess the individual parasitic burden. Four species were found infected, with ranges of prevalence in parenthesis: Phyllocaulis variegatus (7% to 33.3%); Bradybaena similaris (11.7% to 24.1%); Belocaulus angustipes (8.3% ) and Phyllocaulis soleiformis (3.3% to 14.2%). Parasitic burden varied from 1 to 75 with P. variegatus, 1 to 98 with B. similaris, 1 to 13 with B. angustipes and 1 larvae in each of two specimens of P. soleiformis. P. variegatus was present in all sites and was found infected with the highest prevalence figures and the highest individual parasitic burdens. These data stress the importance of veronicellid slugs as intermediate hosts for A. costaricensis in the endemic areas in Rio Grande do Sul, Brazil

Computed tomography angiography vs 3 T black-blood cardiovascular magnetic resonance for identification of symptomatic carotid plaques.

BACKGROUND: The purpose of this prospective study was to perform a head-to-head comparison of the two methods most frequently used for evaluation of carotid plaque characteristics: Multi-detector Computed Tomography Angiography (MDCTA) and black-blood 3 T-cardiovascular magnetic resonance (bb-CMR) with respect to their ability to identify symptomatic carotid plaques. METHODS: 22 stroke unit patients with unilateral symptomatic carotid disease and >50% stenosis by duplex ultrasound underwent MDCTA and bb-CMR (TOF, pre- and post-contrast fsT1w-, and fsT2w- sequences) within 15 days of symptom onset. Both symptomatic and contralateral asymptomatic sides were evaluated. By bb-CMR, plaque morphology, composition and prevalence of complicated AHA type VI lesions (AHA-LT6) were evaluated. By MDCTA, plaque type (non-calcified, mixed, calcified), plaque density in HU and presence of ulceration and/or thrombus were evaluated. Sensitivity (SE), specificity (SP), positive and negative predictive value (PPV, NPV) were calculated using a 2-by-2-table. RESULTS: To distinguish between symptomatic and asymptomatic plaques AHA-LT6 was the best CMR variable and presence / absence of plaque ulceration was the best CT variable, resulting in a SE, SP, PPV and NPV of 80%, 80%, 80% and 80% for AHA-LT6 as assessed by bb-CMR and 40%, 95%, 89% and 61% for plaque ulceration as assessed by MDCTA. The combined SE, SP, PPV and NPV of bb-CMR and MDCTA was 85%, 75%, 77% and 83%, respectively. CONCLUSIONS: Bb-CMR is superior to MDCTA at identifying symptomatic carotid plaques, while MDCTA offers high specificity at the cost of low sensitivity. Results were only slightly improved over bb-CMR alone when combining both techniques.

Postmortem computed tomography angiography vs. conventional autopsy: advantages and inconveniences of each method.

PURPOSE: Postmortem computed tomography angiography (PMCTA) was introduced into forensic investigations a few years ago. It provides reliable images that can be consulted at any time. Conventional autopsy remains the reference standard for defining the cause of death, but provides only limited possibility of a second examination. This study compares these two procedures and discusses findings that can be detected exclusively using each method. MATERIALS AND METHODS: This retrospective study compared radiological reports from PMCTA to reports from conventional autopsy for 50 forensic autopsy cases. Reported findings from autopsy and PMCTA were extracted and compared to each other. PMCTA was performed using a modified heart-lung machine and the oily contrast agent Angiofil® (Fumedica AG, Muri, Switzerland). RESULTS: PMCTA and conventional autopsy would have drawn similar conclusions regarding causes of death. Nearly 60 % of all findings were visualized with both techniques. PMCTA demonstrates a higher sensitivity for identifying skeletal and vascular lesions. However, vascular occlusions due to postmortem blood clots could be falsely assumed to be vascular lesions. In contrast, conventional autopsy does not detect all bone fractures or the exact source of bleeding. Conventional autopsy provides important information about organ morphology and remains the only way to diagnose a vital vascular occlusion with certitude. CONCLUSION: Overall, PMCTA and conventional autopsy provide comparable findings. However, each technique presents advantages and disadvantages for detecting specific findings. To correctly interpret findings and clearly define the indications for PMCTA, these differences must be understood.

A fully echo-guided trans-apical aortic valve implantation.

The trans-apical aortic valve implantation (TA-AVI) is an established technique for high-risk patients requiring aortic valve replacement. Traditionally, preoperative (computed tomography (CT) scan, coronary angiogram) and intra-operative imaging (fluoroscopy) for stent-valve positioning and implantation require contrast medium injections. To preserve the renal function in elderly patients suffering from chronic renal insufficiency, a fully echo-guided trans-catheter valve implantation seems to be a reasonable alternative. We report the first successful TA-AVI procedure performed solely under trans-oesophageal echocardiogram control, in the absence of contrast medium injections.

Neuroimaging techniques in Alzheimer's disease

Neuroimaging techniques provide valuable tools for diagnosing Alzheimer's disease (AD), monitoring disease progression and evaluating responses to treatment. There is currently a wide array of techniques available including computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and, for recording electrical brain activity, electroencephalography (EEG). The choice of technique depends on the contrast between tissues of interest, spatial resolution, temporal resolution, requirements for functional data and the probable number of scans required. For example, while PET, CT and MRI can be used to differentiate between AD and other dementias, MRI is safer and provides better contrast of soft tissues. Neuroimaging is a technique spanning many disciplines and requires effective communication between doctors requesting a scan of a patient or group of patients and those with technical expertise. Consideration and discussion of the most suitable type of scan and the necessary settings to achieve the best results will help ensure appropriate techniques are chosen and used effectively. Neuroimaging techniques are currently expanding understanding of the structural and functional changes that occur in dementia. Further research may allow identification of early neurological signs ofAD, before clinical symptoms are evident, providing the opportunity to test preventative therapies. CombiningMRI and machine learning techniques may be a powerful approach to improve diagnosis ofAD and to predict clinical outcomes.

Supervivencia de los enfermos con aneurisma de aorta abdominal tratados con técnica endovascular

La reparació endovascular dels aneurismes d’aorta abdominal (AAA) és cada cop més usada, encara que només conta amb 15 anys des de l’inici amb una ràpida evolució. Davant la falta d’estudis amb resultats a més de 10 anys. L’objectiu del treball es analitzar prospectivament la supervivència dels 172 pacients tractats en nostre centre desde 06/1998 fins 01/2008, amb seguiment a 10 anys. S’obtingué una supervivència del 61% als 6 anys (error 5%), als 9 anys de 51% (error 7%), a 10 anys 47% (error 11%). La causa més freqüent de mort va ser per neoplàsia.

Volumetric quantification of atherosclerotic plaque in CT considering partial volume effect.

Coronary artery calcification (CAC) is quantified based on a computed tomography (CT) scan image. A calcified region is identified. Modified expectation maximization (MEM) of a statistical model for the calcified and background material is used to estimate the partial calcium content of the voxels. The algorithm limits the region over which MEM is performed. By using MEM, the statistical properties of the model are iteratively updated based on the calculated resultant calcium distribution from the previous iteration. The estimated statistical properties are used to generate a map of the partial calcium content in the calcified region. The volume of calcium in the calcified region is determined based on the map. The experimental results on a cardiac phantom, scanned 90 times using 15 different protocols, demonstrate that the proposed method is less sensitive to partial volume effect and noise, with average error of 9.5% (standard deviation (SD) of 5-7mm(3)) compared with 67% (SD of 3-20mm(3)) for conventional techniques. The high reproducibility of the proposed method for 35 patients, scanned twice using the same protocol at a minimum interval of 10 min, shows that the method provides 2-3 times lower interscan variation than conventional techniques.

Síndrome compartimental abdominal en el paciente crítico con patología médica

Estudi observacional de 60 pacients ingressats a la UCI per patologia extraabdominal, que demostra alta incidència de HIA (90%) i que el valor de PIA màxima és marcador pronòstic del SCA però no prediu mortalitat. Els graus més elevats d’HIA s’associen amb VMI, shock, SDRA, insuficiència renal e ili. La PIA màxima del pacient crític no neurològic (sèptic, traumatològic i respiratori) és més elevada que la del no neurològic, 20 i 16 mmHg respectivament. El valor de PIA màxima que millor prediu insuficiència renal al pacient no neurològic és 18,5mmHg. La PIA màxima es correlaciona amb l’estada a UCI i hospitalària.

Imaging of Lemierre Syndrome in children and young adultsA case-series analysis

Background / Purpose : Lemierre Syndrome (LS) is defined by a recent oro-pharangeal infection, the clinical presence or radiological demonstration of internal jugular vein (IJV) thrombosis and documented anaerobe germ, principally Fusobacterium necrophorum (Fn) leading to septicaemia and septic embolization. It is a rare infection described since 1900 and it nearly disappeared since the beginning of the antibiotic area. Even if it is seldom described in the literature, this infection is reappearing in the last 10 years, either because of the increase of antibiotic resistance or by modification of antibiotic prescription. The aim of this study is to describe the role of medical imaging in the diagnosis, staging and follow up of Lemierre syndrome, as well as to describe the ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) findings of this rare disease. Patients and methods : Radiological and medical files of patients diagnosed with Lemierre syndrome in the past 6 years at CHUV hospital were analysed retrospectively. The CT scan, US, colour Doppler US (CDUS) and MRI examinations that were performed have been examined so as to define their specific imaging findings. Results IJV thrombosis was demonstrated in 2 cases by US, by CT in 6 cases and MRI in one case. Septic pulmonary emboli were detected by CT in 5 patients. Complications of the LS were depicted by MR in one case and by CT in 1 case. Conclusion : In the appropriate clinical settings, US, CT or MR evidence of IJV thrombosis and chest CT suggestive of septic emboli, should lead the physician to consider the diagnosis of LS. As a consequence, imaging allows a faster diagnosis and a more efficient treatment of this infection, which in case of insufficient therapy can lead to death.

Detection of the acute phase of abdominal angiostrongyliasis with a parasite-specific IgG enzyme linked immunosorbent assay

Angiostrongylus costaricensis may cause intestinal lesions of varied severity when it accidentally infects man in Central and South America. First-stage larvae have never been detected in stools. Therefore, a parasite-specific IgG ELISA was evaluated for the determination of the acute phase of infection. The specificity and the sensitivity of the immunoassay was shown to be 76.2% and 91.1%, respectively. Eight serum samples taken from patients with histopathological diagnosis, at different time points (3 to 15 months) after surgical treatment, showed a sharp and early decline in antibody reactivity. The titration of anti-A. costaricensis antibodies has proved to be a useful method for the diagnosis of acute abdominal angiostrongyliasis.

Implicacions diagnòstiques del strem-1 (soluble triggering receptor expressed on myeloid cells) en malalts amb síndrom del distress respiratori agut (sdra) i patologia abdominal. estudi preliminar

Els pacients amb patologia abdominal aguda poden desenvolupar una insuficiència respiratòria secundària a la resposta inflamatòria generada o a una pneumònia nosocomial. El mesurament del “soluble *triggering receptor expressed on myeloid cells 1” (sTREM-1) en líquid alveolar, pleural, sinovial o cefalorraquidi ha demostrat la seva utilitat en el diagnòstic d'infecció. Es va determinar el sTREM-1 alveolar i peritoneal en pacients amb quadre abdominal agut més síndrom de distress respiratori agut (SDRA). Es va concloure que el sTREM-1 és útil per diagnosticar infeccions abdominals i pulmonars en aquests pacients i que la relació sTREM-1 alveolar/peritoneal podria ser útil per determinar el focus infecciós.