Pitfalls in post-mortem CT-angiography--intravascular contrast induces post-mortem pericardial effusion

We present a case where multi-phase post-mortem computed tomography angiography (PMCTA) induced a hemorrhagic pericardial effusion during the venous phase of angiography. Post-mortem non-contrast CT (PMCT) suggested the presence of a ruptured aortic dissection. This diagnosis was confirmed by PMCTA after pressure controlled arterial injection of contrast. During the second phase of multi-phase PMCTA the presence of contrast leakage from the inferior cava vein into the pericardial sac was noted. Autopsy confirmed the post-mortem nature of this vascular tear. This case teaches us an important lesson: it underlines the necessity to critically analyze PMCT and PMCTA images in order to distinguish between artifacts, true pathologies and iatrogenic findings. In cases with ambiguous findings such as the case reported here, correlation of imaging findings with autopsy is elementary.

Essentials of forensic post-mortem MR imaging in adults

Post-mortem MR (PMMR) imaging is a powerful diagnostic tool with a wide scope in forensic radiology. In the past 20 years, PMMR has been used as both an adjunct and an alternative to autopsy. The role of PMMR in forensic death investigations largely depends on the rules and habits of local jurisdictions, availability of experts, financial resources, and individual case circumstances. PMMR images are affected by post-mortem changes, including position-dependent sedimentation, variable body temperature and decomposition. Investigators must be familiar with the appearance of normal findings on PMMR to distinguish them from disease or injury. Coronal whole-body images provide a comprehensive overview. Notably, short tau inversion–recovery (STIR) images enable investigators to screen for pathological fluid accumulation, to which we refer as “forensic sentinel sign”. If scan time is short, subsequent PMMR imaging may be focussed on regions with a positive forensic sentinel sign. PMMR offers excellent anatomical detail and is especially useful to visualize pathologies of the brain, heart, subcutaneous fat tissue and abdominal organs. PMMR may also be used to document skeletal injury. Cardiovascular imaging is a core area of PMMR imaging and growing evidence indicates that PMMR is able to detect ischaemic injury at an earlier stage than traditional autopsy and routine histology. The aim of this review is to present an overview of normal findings on forensic PMMR, provide general advice on the application of PMMR and summarise the current literature on PMMR imaging of the head and neck, cardiovascular system, abdomen and musculoskeletal system.

MR Spectroscopy and Spectroscopic Imaging for Evaluation of Skeletal Muscle Metabolism: Basics and Applications in Metabolic Diseases

Magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) provide metabolic information on the musculoskeletal system, thus helping to understand the biochemical and pathophysiological nature of numerous diseases. In particular, MRS has been used to study the energy metabolism of muscular tissue since the very beginning of magnetic resonance examinations in humans when small-bore magnets for studies of the limbs became available. Even more than in other organs, the observation of non-proton-nuclei was important in muscle tissue. Spatial localization was less demanding in these studies, however, high temporal resolution was necessary to follow metabolism during exercise and recovery. The observation of high-energy phosphates during and after the application of workload gives insight into oxidative phosphorylation, a process that takes place in the mitochondria and characterizes impaired mitochondrial function. New applications in insulin-resistant patients followed the development of volume-selective 1H-MRS in whole-body magnets. Nowadays, multinuclear MRS and MRSI of the musculoskeletal system provide several windows to vital biochemical pathways noninvasively. It is shown how MRS and MRSI have been used in numerous diseases to characterize an involvement of the muscular metabolism.

C-reactive protein predicts mortality in patients referred for coronary angiography and symptoms of heart failure with preserved ejection fraction

AIMS Heart failure with preserved ejection fraction (HFpEF) has a different pathophysiological background compared to heart failure with reduced ejection fraction (HFrEF). Tailored risk prediction in this separate heart failure group with a high mortality rate is of major importance. Inflammation may play an important role in the pathogenesis of HFpEF because of its significant contribution to myocardial fibrosis. We therefore aimed to assess the predictive value of C-reactive protein (CRP) in patients with HFpEF. METHODS AND RESULTS Plasma levels of CRP were determined in 459 patients with HFpEF in the LUdwigshafen Risk and Cardiovascular Health (LURIC) study using a high-sensitivity assay. During a median follow-up of 9.7 years 40% of these patients died. CRP predicted all-cause mortality with an adjusted hazard ratio (HR) of 1.20 [95% confidence interval (CI) 1.02-1.40, P = 0.018] and cardiovascular mortality with a HR of 1.32 (95% CI 1.08-1.62, P = 0.005) per increase of one standard deviation. CRP was a significantly stronger mortality predictor in HFpEF patients than in a control group of 522 HFrEF patients (for interaction, P = 0.015). Furthermore, CRP added prognostic value to N-terminal pro B-type natriuretic peptide (Nt-proBNP): the lowest 5-year mortality rate of 6.8% was observed for patients in the lowest tertile of Nt-proBNP as well as CRP. The mortality risk peaked in the group combining the highest values of Nt-proBNP and CRP with a 5-year rate of 36.5%. CONCLUSION It was found that CRP was an independent and strong predictor of mortality in HFpEF. This observation may reflect immunological processes with an adverse impact on the course of HFpEF.

Lettre aux auteurs juifs d'un mémoire adressé à Mr. Teller

par J. A. de Luc

Multi-phase postmortem CT angiography: recognizing technique-related artefacts and pitfalls

BACKGROUND AND PURPOSE Multi-phase postmortem CT angiography (MPMCTA) is increasingly being recognized as a valuable adjunct medicolegal tool to explore the vascular system. Adequate interpretation, however, requires knowledge about the most common technique-related artefacts. The purpose of this study was to identify and index the possible artefacts related to MPMCTA. MATERIAL AND METHODS An experienced radiologist blinded to all clinical and forensic data retrospectively reviewed 49 MPMCTAs. Each angiographic phase, i.e. arterial, venous and dynamic, was analysed separately to identify phase-specific artefacts based on location and aspect. RESULTS Incomplete contrast filling of the cerebral venous system was the most commonly encountered artefact, followed by contrast agent layering in the lumen of the thoracic aorta. Enhancement or so-called oedematization of the digestive system mucosa was also frequently observed. CONCLUSION All MPMCTA artefacts observed and described here are reproducible and easily identifiable. Knowledge about these artefacts is important to avoid misinterpreting them as pathological findings.

Outcome of patients with occlusions of the internal carotid artery or the main stem of the middle cerebral artery with NIHSS score of less than 5: comparison between thrombolysed and non-thrombolysed patients

BACKGROUND AND PURPOSE The use of thrombolysis in patients with minor neurological deficits and large vessel occlusion is controversial. METHODS We compared the outcome of patients with low National Institutes of Health Stroke Scale (NIHSS) scores and large vessel occlusions between thrombolysed and non-thrombolysed patients. RESULTS 88 (1.7%) of 5312 consecutive patients with acute (within 24 h) ischaemic stroke had occlusions of the internal carotid or the main stem of the middle cerebral artery and baseline NIHSS scores ≤5.47 (53.4%) were treated without thrombolysis, and 41 (46.6%) received intravenous thrombolysis, endovascular therapy or both. Successful recanalisation on MR or CT angiography at 24 h was more often observed in thrombolysed than in non-thrombolysed patients (78.9% versus 10.5%; p<0.001). Neurological deterioration (increase of NIHSS score ≥1 compared to baseline) was observed in 22.7% of non-thrombolysed versus 10.3% of thrombolysed after 24 h (p=0.002), in 33.3% versus 12.5% at hospital discharge (p=0.015) and in 41.4% versus 15% at 3 months (p<0.001). Symptomatic intracerebral haemorrhage occurred in two (asymptomatic in five) thrombolysed and in none (asymptomatic in three) non-thrombolysed. Thrombolysis was an independent predictor of favourable outcome (p=0.030) but not survival (p=0.606) at 3 months. CONCLUSIONS Non-thrombolysed patients with mild deficits and large vessel occlusion deteriorated significantly more often within 3 months than thrombolysed patients. Symptomatic intracerebral haemorrhages occurred in less than 5% of patients in both groups. These data suggest that thrombolysis is safe and effective in these patients. Therefore, randomised trials in patients with large vessel occlusions and mild or rapidly improving symptoms are needed.

Interactive Segmentation of MR Images from Brain Tumor Patients

Medical doctors often do not trust the result of fully automatic segmentations because they have no possibility to make corrections if necessary. On the other hand, manual corrections can introduce a user bias. In this work, we propose to integrate the possibility for quick manual corrections into a fully automatic segmentation method for brain tumor images. This allows for necessary corrections while maintaining a high objectiveness. The underlying idea is similar to the well-known Grab-Cut algorithm, but here we combine decision forest classification with conditional random field regularization for interactive segmentation of 3D medical images. The approach has been evaluated by two different users on the BraTS2012 dataset. Accuracy and robustness improved compared to a fully automatic method and our interactive approach was ranked among the top performing methods. Time for computation including manual interaction was less than 10 minutes per patient, which makes it attractive for clinical use.

Postmortem MR quantification of the heart for characterization and differentiation of ischaemic myocardial lesions.

OBJECTIVES Recently, an MRI quantification sequence has been developed which can be used to acquire T1- and T2-relaxation times as well as proton density (PD) values. Those three quantitative values can be used to describe soft tissue in an objective manner. The purpose of this study was to investigate the applicability of quantitative cardiac MRI for characterization and differentiation of ischaemic myocardial lesions of different age. MATERIALS AND METHODS Fifty post-mortem short axis cardiac 3 T MR examinations have been quantified using a quantification sequence. Myocardial lesions were identified according to histology and appearance in MRI images. Ischaemic lesions were assessed for mean T1-, T2- and proton density values. Quantitative values were plotted in a 3D-coordinate system to investigate the clustering of ischaemic myocardial lesions. RESULTS A total of 16 myocardial lesions detected in MRI images were histologically characterized as acute lesions (n = 8) with perifocal oedema (n = 8), subacute lesions (n = 6) and chronic lesions (n = 2). In a 3D plot comprising the combined quantitative values of T1, T2 and PD, the clusters of all investigated lesions could be well differentiated from each other. CONCLUSION Post-mortem quantitative cardiac MRI is feasible for characterization and discrimination of different age stages of myocardial infarction. KEY POINTS • MR quantification is feasible for characterization of different stages of myocardial infarction. • The results provide the base for computer-aided MRI cardiac infarction diagnosis. • Diagnostic criteria may also be applied for living patients.

Temperature dependence of postmortem MR quantification for soft tissue discrimination.

OBJECTIVES To investigate and correct the temperature dependence of postmortem MR quantification used for soft tissue characterization and differentiation in thoraco-abdominal organs. MATERIAL AND METHODS Thirty-five postmortem short axis cardiac 3-T MR examinations were quantified using a quantification sequence. Liver, spleen, left ventricular myocardium, pectoralis muscle and subcutaneous fat were analysed in cardiac short axis images to obtain mean T1, T2 and PD tissue values. The core body temperature was measured using a rectally inserted thermometer. The tissue-specific quantitative values were related to the body core temperature. Equations to correct for temperature differences were generated. RESULTS In a 3D plot comprising the combined data of T1, T2 and PD, different organs/tissues could be well differentiated from each other. The quantitative values were influenced by the temperature. T1 in particular exhibited strong temperature dependence. The correction of quantitative values to a temperature of 37 °C resulted in better tissue discrimination. CONCLUSION Postmortem MR quantification is feasible for soft tissue discrimination and characterization of thoraco-abdominal organs. This provides a base for computer-aided diagnosis and detection of tissue lesions. The temperature dependence of the T1 values challenges postmortem MR quantification. Equations to correct for the temperature dependence are provided. KEY POINTS • Postmortem MR quantification is feasible for soft tissue discrimination and characterization • Temperature dependence of the T1 values challenges the MR quantification approach • The results provide the basis for computer-aided postmortem MRI diagnosis • Diagnostic criteria may also be applied for living patients.

Von Willebrand Factor Improves Risk Prediction in Addition to N-Terminal Pro-B-type Natriuretic Peptide in Patients Referred to Coronary Angiography and Signs and Symptoms of Heart Failure and Preserved Ejection Fraction.

BACKGROUND Heart failure with preserved ejection fraction (HFpEF) represents a growing health burden associated with substantial mortality and morbidity. Consequently, risk prediction is of highest importance. Endothelial dysfunction has been recently shown to play an important role in the complex pathophysiology of HFpEF. We therefore aimed to assess von Willebrand factor (vWF), a marker of endothelial damage, as potential biomarker for risk assessment in patients with HFpEF. METHODS AND RESULTS Concentrations of vWF were assessed in 457 patients with HFpEF enrolled as part of the LUdwigshafen Risk and Cardiovascular Health (LURIC) study. All-cause mortality was observed in 40% of patients during a median follow-up time of 9.7 years. vWF significantly predicted mortality with a hazard ratio (HR) per increase of 1 SD of 1.45 (95% confidence interval, 1.26-1.68; P<0.001) and remained a significant predictor after adjustment for age, sex, body mass index, N-terminal pro-B-type natriuretic peptide (NT-proBNP), renal function, and frequent HFpEF-related comorbidities (adjusted HR per 1 SD, 1.22; 95% confidence interval, 1.05-1.42; P=0.001). Most notably, vWF showed additional prognostic value beyond that achievable with NT-proBNP indicated by improvements in C-Statistic (vWF×NT-proBNP: 0.65 versus NT-proBNP: 0.63; P for comparison, 0.004) and category-free net reclassification index (37.6%; P<0.001). CONCLUSIONS vWF is an independent predictor of long-term outcome in patients with HFpEF, which is in line with endothelial dysfunction as potential mediator in the pathophysiology of HFpEF. In particular, combined assessment of vWF and NT-proBNP improved risk prediction in this vulnerable group of patients.

Metastases in normal-sized pelvic lymph nodes: detection with diffusion-weighted MR imaging

PURPOSE To prospectively assess the diagnostic performance of diffusion-weighted (DW) magnetic resonance (MR) imaging in the detection of pelvic lymph node metastases in patients with prostate and/or bladder cancer staged as N0 with preoperative cross-sectional imaging. MATERIALS AND METHODS This study was approved by an independent ethics committee. Written informed consent was obtained from all patients. Patients with no enlarged lymph nodes on preoperative cross-sectional images who were scheduled for radical resection of the primary tumor and extended pelvic lymph node dissection were enrolled. All patients were examined with a 3-T MR unit, and examinations included conventional and DW MR imaging of the entire pelvis. Image analysis was performed by three independent readers blinded to any clinical information. Metastases were diagnosed on the basis of high signal intensity on high b value DW MR images and morphologic features (shape, border). Histopathologic examination served as the standard of reference. Sensitivity and specificity were calculated, and bias-corrected 95% confidence intervals (CIs) were obtained with the bootstrap method. The Fleiss and Cohen κ and median test were applied for statistical analyses. RESULTS A total of 4846 lymph nodes were resected in 120 patients. Eighty-eight lymph node metastases were found in 33 of 120 patients (27.5%). Short-axis diameter of these metastases was less than or equal to 3 mm in 68, more than 3 mm to 5 mm in 13, more than 5 mm to 8 mm in five; and more than 8 mm in two. On a per-patient level, the three readers correctly detected metastases in 26 (79%; 95% CI: 64%, 91%), 21 (64%; 95% CI: 45%, 79%), and 25 (76%; 95% CI: 60%, 90%) of the 33 patients with metastases, with respective specificities of 85% (95% CI: 78%, 92%), 79% (95% CI: 70%, 88%), and 84% (95% CI: 76%, 92%). Analyzed according to hemipelvis, lymph node metastases were detected with histopathologic examination in 44 of 240 pelvic sides (18%); the three readers correctly detected these on DW MR images in 26 (59%; 95% CI: 45%, 73%), 19 (43%; 95% CI: 27%, 57%), and 28 (64%; 95% CI: 47%, 78%) of the 44 cases. CONCLUSION DW MR imaging enables noninvasive detection of small lymph node metastases in normal-sized nodes in a substantial percentage of patients with prostate and bladder cancer diagnosed as N0 with conventional cross-sectional imaging techniques.