Is Additive Manufacturing an Environmentally and Economically Preferred Alternative for Mass Production?

The manufacturing sector accounts for a large percentage of global energy use and greenhouse gas emissions, and there is growing interest in the potential of additive manufacturing (AM) to reduce the sector's environmental impacts. Across multiple industries, AM has been used to reduce material use in final parts by 35-80%, and recent publications have predicted that AM will enable the fabrication of customized products locally and on-demand, reducing shipping and material waste. In many contexts, however, AM is not a viable alternative to traditional manufacturing methods due to its high production costs. And in high-volume mass production, AM can lead to increased energy use and material waste, worsening environmental impacts compared to traditional production methods. Whether AM is an environmentally and economically preferred alternative to traditional manufacturing depends on several hidden aspects of AM that are not readily apparent when comparing final products, including energy-intensive and expensive material feedstocks, excessive material waste during production, high machine costs, and slow rates of production. We systematically review comparative studies of the environmental impacts and costs of AM in contrast with traditional manufacturing methods and identify the conditions under which AM is the environmentally and economically preferred alternative. We find that AM has lower production costs and environmental impacts when production volumes are relatively low (below ∼1,000 per year for environmental impacts and below 42-87,000 per year for costs, depending on the AM process and part geometry) or the parts are small and would have high material waste if traditionally manufactured. In cases when the geometric freedom of AM enables performance improvements that reduce environmental impacts and costs during a product's use phase, these can counteract the higher production impacts of AM, making it the preferred alternative at larger production volumes. AM's ability to be environmentally and economically beneficial for mass manufacturing in a wider variety of contexts is dependent on reducing the cost and energy intensity of material feedstock production, eliminating the need for support structures, raising production speeds, and reducing per unit machine costs. These challenges are not primarily caused by economies of scale, and therefore, they are not likely to be addressed by the increasing expansion of the AM sector. Instead, they will require fundamental advances in material science, AM production technologies, and computer-aided design software.

Establishing Local Diagnostic Reference Levels in IR Procedures with Dose Management Software.

PURPOSE: To obtain local diagnostic reference levels (DRLs) in diagnostic and therapeutic IR procedures with dose management software to improve radiation protection. MATERIALS AND METHODS: Dose data of various vascular and nonvascular IR procedures performed within 18 months were collected and analyzed with dose management software. To account for different levels of complexity, procedures were subdivided into simple, standard, and difficult procedures as graded by interventional radiologists. Based on these analyses, local DRLs (given as kerma-area product [KAP]) were proposed. Comparison with dose data of others was conducted, and Spearman correlation coefficients were calculated to evaluate relationships between dose metrics. RESULTS: Analysis included 1,403 IR procedures (simple/standard/difficult, n = 346/702/355). Within the same procedure, KAP tended to increase with level of complexity. Overall, very strong correlation between KAP (Gy ∙ cm2) and cumulative air kerma (KA,R; Gy) was observed, and moderate to strong correlation between KAP and time and KA,R and time was observed. For simple procedures, strong correlation was seen between KAP and time and KA,R and time; for standard and difficult procedures, only moderate correlation was seen. Correlation between KAP and time and KA,R and time was strong in nonvascular procedures but only moderate in vascular procedures. CONCLUSIONS: Dose management software can be used to derive local DRLs for various IR procedures, taking into consideration different levels of complexity. Proposed local DRLs can contribute to obtaining detailed national DRLs as part of efforts to improve patients' radiation protection further.

Combined Use of a Patient Dose Monitoring System and a Real-Time Occupational Dose Monitoring System for Fluoroscopically Guided Interventions.

PURPOSE: To determine the effect on patient radiation exposure of the combined use of a patient dose monitoring system and real-time occupational dose monitoring during fluoroscopically guided interventions (FGIs). MATERIALS AND METHODS: Patient radiation exposure, in terms of the kerma area product (KAP; Gy ∙ cm(2)), was measured in period 1 with a patient dose monitoring system, and a real-time occupational dose monitoring system was additionally applied in period 2. Mean/median KAP in 19 different types of FGIs was analyzed in both periods for two experienced interventional radiologists combined as well as individually. Patient dose and occupational dose were correlated, applying Pearson and Spearman correlation coefficients. RESULTS: Although FGIs were similar in numbers and types over both periods, a substantial decrease was found for period 2 in total mean ± SD/median KAP for both operators together (period 1, 47 Gy ∙ cm(2) ± 67/41 Gy ∙ cm(2); period 2, 37 Gy ∙ cm(2) ± 69/34 Gy ∙ cm(2)) as well as for each individual operator (for all, P < .05). Overall, KAP declined considerably in 15 of 19 types of FGIs in period 2. Mean accumulated dose per intervention was 4.6 µSv, and mean dose rate was 0.24 mSv/h. There was a strong positive correlation between patient and occupational dose (r = 0.88). CONCLUSIONS: Combined use of a patient dose monitoring system and a real-time occupational dose monitoring system in FGIs significantly lessens patient and operator doses.

Improving Patient Safety: Implementing Dose Monitoring Software in Fluoroscopically Guided Interventions.

PURPOSE: To assess whether dose monitoring software can be successfully implemented in fluoroscopically guided interventions and to provide dose data based on levels of complexity. MATERIALS AND METHODS: After launching the software (DoseWatch; GE Healthcare Systems, Buc, France), data were collected for 6 months and analyzed by means of kerma-area product (KAP; Gy/cm(2)), cumulative air kerma (KA,R; Gy), and fluoroscopic time (minutes). Data analysis was executed by level of complexity as graded by the operators. Complexity grading was based on factors such as tortuosity and calcification of vessel, variant anatomy, and patient cooperation. RESULTS: The software successfully transferred dose data of 357 fluoroscopically guided procedures. KAP was 0.238-400 Gy/cm(2) with mean, median, and 75th percentile values of 46.0 Gy/cm(2), 163.2 Gy/cm(2), and 541.1 Gy/cm(2) (KA,R, 0.013-4.1 Gy; mean, median, 75th percentile, 0.48 Gy, 0.97 Gy, 3.98 Gy). Highest dose values were seen in transarterial chemoembolization (KAP mean, median, 75th percentile, 229.5 Gy/cm(2), 216.4 Gy/cm(2), 299.9 Gy/cm(2); KA,R mean, median, 75th percentile, 1.9 Gy, 1.2 Gy, 1.7 Gy). Analysis revealed that the level of complexity strongly correlated with KAP (r = 0.88; P < .001) whereas there was no direct correlation of KAP and fluoroscopy time. During the same intervention, KA,R and fluoroscopy time increased with level of complexity, but the correlation was not statistically significant. CONCLUSIONS: Implementation of dose monitoring software in fluoroscopically guided interventions can be successfully accomplished, and it facilitates data comparison.

The effect of Er,Cr:YSGG laser irradiation on titanium discs with microtextured surface morphology.

Both mechanical and chemical methods can be used to clean and decontaminate implant surfaces. Incomplete debridement of infected tissue and failure to clear endotoxins can result in graft failure and a return of the defect. Recently, lasers have gained popularity for sterilizing and cleaning implant surfaces. We determined the effects of laser treatment on the surface characteristics of titanium discs with a Laser-Lok surface. The discs were irradiated with an erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser under various conditions (R1-9). Scanning electron microscopy was used to evaluate the surface. Considerable surface alterations such as melting and flattening were seen at R6 (2 W, 20 Hz, 4 mm, 45 s) and R8 (3 W, 25 Hz, 2 mm, 45 s). In addition, cracking was seen at R8. The laser parameters should be optimized to conserve surface characteristics during the irradiation of implant surfaces.

Characterization and differentiation of body fluids, putrefaction fluid, and blood using Hounsfield unit in postmortem CT.

The purpose of the present study was to evaluate the ranges of Hounsfield unit (HU) found in body fluids, putrefaction fluids, and blood on postmortem CT and how these ranges are affected by postmortem interval, temperatures, and CT beam energy. Body fluids, putrefaction fluids, and blood from a total of 53 corpses were analyzed to determine the ranges of HU values from postmortem CT images that were taken prior to autopsy. The fluids measured in CT images were obtained at autopsy and examined in terms of macroscopic and microscopic appearances. Body fluids and blood were also collected in plastic bottles, which were subjected to CT scans at different beam energies (80-130 kV) and at various fluid temperatures (4 to 40 °C). At a postmortem interval of 1 to 4 days, the ranges of HU values of the serous fluids (13-38 HU) and the nonsedimented blood (40-88 HU) did not overlap. In the sedimented blood, the upper serum layer exhibited HU value ranges that overlapped with those of the serous fluids. The putrefaction fluids exhibited a range of HU values between 80 and -130 HU. Elevated HU values were observed in fluids with accretive cell impurities. HU values decreased slightly with increasing temperature and CT beam energy. We concluded that serous fluids and blood in fresh corpses can be characterized and differentiated from each other based on HU value ranges. In contrast, body fluids in decomposed corpses cannot be differentiated by their HU value ranges. Different beam energies and corpse temperatures had only minor influences on HU value ranges and therefore should not be obstacles to the differentiation and characterization of body fluids and blood.

Effects of Er,Cr:YSGG laser irradiation on the surface characteristics of titanium discs: an in vitro study.

Lasers are used to modify the surfaces of dental implants or to decontaminate exposed implant surfaces. However, research is lacking on whether the laser causes any change on the surfaces of titanium implants. We aimed to determine the effects of laser treatment on the surface characteristics of titanium discs. Nine discs were fabricated using grade-V titanium with resorbable blast texturing surface characteristics. The discs were irradiated with an erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser under different experimental conditions (R1-9). Scanning electron microscopy was used to evaluate implant surface topography qualitatively, and a mechanical contact profilometer was used to evaluate surface roughness. The R3 and R5 parameters caused no measurable change. Minor cracks and grooves were observed in discs treated with the R1, R2, R4, R7 and R9 parameters. Major changes, such as melting, flattening and deep crack formation, were observed in discs subjected to R6 (2 W, 30 Hz, 2 mm. distance, 30 s) and R8 (3 W, 25 Hz, 2 mm. distance, 45 s) parameters. The lowest surface roughness value was obtained with the R8 parameter. Irradiation distance, duration, frequency and power were the most significant factors affecting surface roughness. Parameters such as wavelength, output power, energy, dose and duration should be considered during irradiation. The results of this study indicate that the distance between the laser tip and the irradiated surface should also be considered.

A robotic needle-positioning and guidance system for CT-guided puncture: Ex vivo results.

PURPOSE: To test the feasibility of a robotic needle-guidance platform during CT-guided puncture ex vivo. MATERIAL AND METHODS: Thin copper wires inserted into a torso phantom served as targets. The phantom was placed on a carbon plate and the robot-positioning unit (RPU) of the guidance platform (iSYS Medizintechnik GmbH, Kitzbuehel, Austria) was attached. Following CT imaging and automatic registration a double oblique trajectory was planned and the RPU was remotely moved into appropriate position and angulation. A 17G-puncture needle was then manually inserted until the preplanned depth, permanently guided by the RPU. The CT scan was repeated and the distance between the actual needle tip and the target was evaluated. RESULTS: Automatic registration was successful in ten experiments and the median duration of an experiment was 9.6 (6.4-46.0) minutes. The angulation of the needle path in x-y and z-axis was within 15.6° to 32.6°, and -32.8° to 3.2°, respectively and the needle insertion depth was 92.8 ± 14.4 mm. The Euclidean distance between the actual needle tip and the target was 2.3 ± 0.8 (range, 0.9-3.7) mm. CONCLUSION: Automatic registration and accurate needle placement close to small targets was demonstrated. Study settings and torso phantom were very close to the clinical reality.

Design of target specific peptide inhibitors using generative deep learning and molecular dynamics simulations.

We introduce a computational approach for the design of target-specific peptides. Our method integrates a Gated Recurrent Unit-based Variational Autoencoder with Rosetta FlexPepDock for peptide sequence generation and binding affinity assessment. Subsequently, molecular dynamics simulations are employed to narrow down the selection of peptides for experimental assays. We apply this computational strategy to design peptide inhibitors that specifically target ß-catenin and NF-κB essential modulator. Among the twelve ß-catenin inhibitors, six exhibit improved binding affinity compared to the parent peptide. Notably, the best C-terminal peptide binds ß-catenin with an IC50 of 0.010 ± 0.06 µM, which is 15-fold better than the parent peptide. For NF-κB essential modulator, two of the four tested peptides display substantially enhanced binding compared to the parent peptide. Collectively, this study underscores the successful integration of deep learning and structure-based modeling and simulation for target specific peptide design.

Quantification of popliteal artery deformation during leg flexion in subjects with peripheral artery disease: a pilot study.

PURPOSE: To quantify the in vivo deformations of the popliteal artery during leg flexion in subjects with clinically relevant peripheral artery disease (PAD). METHODS: Five patients (4 men; mean age 69 years, range 56-79) with varying calcification levels of the popliteal artery undergoing endovascular revascularization underwent 3-dimensional (3D) rotational angiography. Image acquisition was performed with the leg straight and with a flexion of 70°/20° in the knee/hip joints. The arterial centerline and the corresponding branches in both positions were segmented to create 3D reconstructions of the arterial trees. Axial deformation, twisting, and curvatures were quantified. Furthermore, the relationships between the calcification levels and the deformations were investigated. RESULTS: An average shortening of 5.9%±2.5% and twist rate of 3.8±2.2°/cm in the popliteal artery were observed. Maximal curvatures in the straight and flexed positions were 0.12±0.04 cm(-1) and 0.24±0.09 cm(-1), respectively. As the severity of calcification increased, the maximal curvature in the straight position increased from 0.08 to 0.17 cm(-1), while an increase from 0.17 to 0.39 cm(-1) was observed for the flexed position. Axial elongations and arterial twisting were not affected by the calcification levels. CONCLUSION: The popliteal artery of patients with symptomatic PAD is exposed to significant deformations during flexion of the knee joint. The severity of calcification directly affects curvature, but not arterial length or twisting angles. This pilot study also showed the ability of rotational angiography to quantify the 3D deformations of the popliteal artery in patients with various levels of calcification.

Percutaneous transhepatic biliary puncture simulator: a cord network prototype.

BACKGROUND: The aim of this study was to present a percutaneous transhepatic biliary puncture simulator that can be used without radiation exposure and that reflects the conventional anatomy of the biliary ducts and its vicinity structures. METHODS: An anatomically based model of the biliary tree was developed using a cord network fixed to a wooden frame. The skin, ribs, intercostal muscles, and right lower lobe pleura were simulated using foam sponge, plastic tubes, a polystyrene foam panel, and an air pad, respectively. For the puncture, we used a 20-G Chiba needle and a wire with distal double arches; these were used to troll a cord, simulating the successful puncture of a bile duct. A camera was also placed above the model to allow the trainees to train eye-hand coordination while viewing the image on a monitor in real time. The simulator was tested with 60 radiology residents to evaluate the confidence and skills transferability of the training model. RESULTS: After receiving an introduction of the system and 5 min of training under tutor surveillance, all participants were able to troll a cord of the biliary simulator by themselves in less than 4 min. Only one participant punctured the simulated pleura. The participants' evaluations showed positive results, with increased user confidence and skills transferability after the training session. CONCLUSIONS: This proposed simulator can be an effective tool to improve a trainee's confidence and competence while achieving procedural and non-procedural interventional radiology skills related to the liver. TRIAL REGISTRATION: Retrospectively registered.

Soft tissue deformation tracking by means of an optimized fiducial marker layout with application to cancer tumors.

OBJECTIVE: Interventional radiology methods have been adopted for intraoperative control of the surgical region of interest (ROI) in a wide range of minimally invasive procedures. One major obstacle that hinders the success of procedures using interventional radiology methods is the preoperative and intraoperative deformation of the ROI. While fiducial markers (FM) tracing has been shown to be promising in tracking such deformations, determining the optimal placement of the FM in the ROI remains a significant challenge. The current study proposes a computational framework to address this problem by preoperatively optimizing the layout of FM, thereby enabling an accurate tracking of the ROI deformations. METHODS: The proposed approach includes three main components: (1) creation of virtual deformation benchmarks, (2) method of predicting intraoperative tissue deformation based on FM registration, and (3) FM layout optimization. To account for the large variety of potential ROI deformations, virtual benchmarks are created by applying a multitude of random force fields on the tumor surface in physically based simulations. The ROI deformation prediction is carried out by solving the inverse problem of finding the smoothest force field that leads to the observed FM displacements. Based on this formulation, a simulated annealing approach is employed to optimize the FM layout that produces the best prediction accuracy. RESULTS: The proposed approach is capable of finding an FM layout that outperforms the rationally chosen layouts by 40% in terms of ROI prediction accuracy. For a maximum induced displacement of 20 mm on the tumor surface, the average maximum error between the benchmarks and our FM-optimized predictions is about 1.72 mm, which falls within the typical resolution of ultrasound imaging. CONCLUSIONS: The proposed framework can optimize FM layout to effectively reduce the errors in the intraoperative deformation prediction process, thus bridging the gap between preoperative imaging and intraoperative tissue deformation.

Temperature-induced configuration changes in hydrogel-coated coils and their relevance in embolization procedures.

BACKGROUND: The present study attempted to demonstrate how the configuration of hydrogel-coated coils is influenced by different temperature exposures. Thirty detachable hydrogel-coated coils were evaluated in an in vitro water immersion test under five different temperature ranges (22.6 °C, 37 °C, 40-50 °C, 50-60 °C, and 60-70 °C). The configuration changes were classified (configuration I, configuration II, and configuration III) according to the curling that occurred during 30 min of immersion. Configuration stability of five Hydrogel-coated coils was also evaluated in a two-step temperature immersion test. RESULTS: All hydrogel-coated coils showed some configuration changes during water immersion. However, a logarithmic transformation of the time and temperature data showed a significant (p < 0.05) negative linear correlation between time and temperature for all coil configurations (configuration I: R = 0.97, configuration II: R = 0.98, configuration III: R = 0.97). The time needed to reach configuration III (complete coiling) was 160.4 ± 41.9 s at 37.5 °C (range: 100-205 s), 45.7 ± 22.2 s at 47.5 °C (range: 23-70 s), 20.2 ± 7.2 s at 57.5 °C (range: 14-32 s), and 10.3 ± 2.4 s at 67.5 °C (range: 7-13 s). CONCLUSIONS: Temperatures above 55 °C induced immediate configurational changes in the hydro-coated coils, achieving complete curling within less than 30 s. Temperatures near 36 °C (normal body temperature) require more time to reach optimal coil curling (configuration III). The optimization of HydroCoil preparation can reduce interventional procedural time and improve clinical results.

Nano-Hydroxyapatite Airborne-Particle Abrasion System as an Alternative Surface Treatment Method on Intraorally Contaminated Titanium Discs.

The aim of this study was to test the nano-hydroxyapatite powder decontamination method on intraorally contaminated titanium discs and to compare this method with current decontamination methods in the treatment of peri-implantitis. Contaminated discs were assigned to six treatment groups (n = 10 each): titanium hand curette; ultrasonic scaler with a plastic tip (appropriate for titanium); ultrasonic scaler with a plastic tip (appropriate for titanium) + H2O2; short-term airflow system (nano-hydroxyapatite airborne-particle abrasion for 30 seconds); long-term airflow system (nano-hydroxyapatite airborne-particle abrasion for 120 seconds); Er:YAG laser (120 mJ/pulse at 10 Hz). There were also two control groups (n = 10 each): contaminated disc (negative control) and sterile disc (positive control). Scanning electron microscopy, energy-dispersive x-ray spectroscopy, and dynamic contact angle analysis were used to determine the most effective surface-treatment method. The highest percentage of carbon (C) atoms was observed in the negative control group, and the lowest percentage of C atoms was found in the long-term airflow group, followed by the short-term airflow, laser, ultrasonic + H2O2, ultrasonic, and mechanical groups. When the groups were examined for wettability, the lowest contact angle degree was observed in the long-term airflow, short-term airflow, and laser groups. Nano-hydroxyapatite and laser treatments for detoxifying and improving infected titanium surfaces may show the most suitable results for reosseointegration.

Reconstruction of a Deformed Tumor Based on Fiducial Marker Registration: A Computational Feasibility Study.

Interstitial photodynamic therapy has shown promising results in the treatment of locally advanced head and neck cancer. In this therapy, systemic administration of a light-sensitive drug is followed by insertion of multiple laser fibers to illuminate the tumor and its margins. Image-based pretreatment planning is employed in order to deliver a sufficient light dose to the complex locally advanced head-and-neck cancer anatomy, in order to meet clinical requirements. Unfortunately, the tumor may deform between pretreatment imaging for the purpose of planning and intraoperative imaging when the plan is executed. Tumor deformation may result from the mechanical forces applied by the light fibers and variation of the patient's posture. Pretreatment planning is frequently done with the assistance of computed tomography or magnetic resonance imaging in an outpatient suite, while treatment monitoring and control typically uses ultrasound imaging due to considerations of costs and availability in the operation room. This article presents a computational method designed to bridge the gap between the 2 imaging events by taking a tumor geometry, reconstructed during preplanning, and by following the displacement of fiducial markers, which are initially placed during the preplanning procedure. The deformed tumor shape is predicted by solving an inverse problem, seeking for the forces that would have resulted in the corresponding fiducial marker displacements. The computational method is studied on spheres of variable sizes and demonstrated on computed tomography reconstructed locally advanced head and neck cancer model. Results of this study demonstrate an average error of less than 1 mm in predicting the deformed tumor shape, where 1 mm is typically the order of uncertainty in distance measurements using magnetic resonance imaging or computed tomography imaging and high-quality ultrasound imaging. This study further demonstrates that the deformed shape can be calculated in a few seconds, making the proposed method clinically relevant.

Disastrous Portal Vein Embolization Turned into a Successful Intervention.

Portal vein embolization (PVE) may be performed before hemihepatectomy to increase the volume of future liver remnant (FLR) and to reduce the risk of postoperative liver insufficiency. We report the case of a 71-year-old patient with hilar cholangiocarcinoma undergoing PVE with access from the right portal vein using a mixture of n-butyl-2-cyanoacrylate and ethiodized oil. During the procedure, nontarget embolization of the left portal vein occurred. An aspiration maneuver of the polymerized plug failed; however, the embolus obstructing portal venous flow in the FLR was successfully relocated into the right portal vein while carefully bypassing the plug with a balloon catheter, inflating the balloon, and pulling the plug into the main right portal vein.

Contrast agents and ionization with respect to safety for patients and doctors.

In hemodialysis patients, radiographic imaging with iodinated contrast medium (ICM) application plays a central role in the diagnosis and/or follow-up of disease-related conditions. Therefore, safety aspects concerning ICM administration and radiation exposure have a great impact on this group of patients. Current hardware and software improvements including the design and synthesis of modern contrast compounds allow the use of very small amounts of ICM in concert with low radiation exposure. Undesirable ICM side effects are divided into type A (predictable reactions such as heat feeling, headache, and contrast-induced acute kidney injury, for example) and type B (nonpredictable or hypersensitivity) reactions; this chapter deals with the latter. The first onset cannot be prevented. To prevent hypersensitivity upon reexposure of ICM, an allergological workup is recommended. If this is not possible and ICM is necessary, the patient should receive a premedication (H1 antihistamine with or without corticosteroids). Current imaging hardware and software improvements (e.g. such as additional filtration of the X-ray beam) allow the use of very small amount of ICM and small X-ray doses. Proper communication among the team involved in the treatment of a patient may allow to apply imaging protocols and efficient imaging strategies limiting radiation exposure to a minimum. Practical recommendations will guide the reader how to use radiation and ICM efficiently to improve both patient and staff safety.

Survival after trepanation-Early cranial surgery from Late Iron Age Switzerland.

Trepanation is defined as the intentional perforation of the cranial vault with removal of a piece of skull bone. In Europe, trepanation is known to have been practiced at least since the Neolithic, and it can still be found today in East African native tribes. Two skulls with lesions from the Late Iron Age site Münsingen-Rain (420-240 BC) were investigated. The aim of this study was to analyse the lesions and to determine whether they were caused by surgical interventions. Both individuals were analysed by current morphologic-anthropological methods and radiological examinations were performed with a multislice CT-scanner. Additionally, this work surveys trepanations reported in Switzerland and calculates survival rates. In Switzerland, 34 individuals with trepanations have been published. As a tendency, the survival rate appears to be relatively high from the Neolithic to Late Antiquity but then decreases until Pre-Modern times. The 78% survival rate in Late Iron Age Switzerland indicates that the surgery was often performed successfully. Skull injuries sustained in conflicts could have been a reason for trepanation during the Iron Age.

Rigor mortis at the myocardium investigated by post-mortem magnetic resonance imaging.

INTRODUCTION: Post-mortem cardiac MR exams present with different contraction appearances of the left ventricle in cardiac short axis images. It was hypothesized that the grade of post-mortem contraction may be related to the post-mortem interval (PMI) or cause of death and a phenomenon caused by internal rigor mortis that may give further insights in the circumstances of death. METHOD AND MATERIALS: The cardiac contraction grade was investigated in 71 post-mortem cardiac MR exams (mean age at death 52 y, range 12-89 y; 48 males, 23 females). In cardiac short axis images the left ventricular lumen volume as well as the left ventricular myocardial volume were assessed by manual segmentation. The quotient of both (LVQ) represents the grade of myocardial contraction. LVQ was correlated to the PMI, sex, age, cardiac weight, body mass and height, cause of death and pericardial tamponade when present. In cardiac causes of death a separate correlation was investigated for acute myocardial infarction cases and arrhythmic deaths. RESULTS: LVQ values ranged from 1.99 (maximum dilatation) to 42.91 (maximum contraction) with a mean of 15.13. LVQ decreased slightly with increasing PMI, however without significant correlation. Pericardial tamponade positively correlated with higher LVQ values. Variables such as sex, age, body mass and height, cardiac weight and cause of death did not correlate with LVQ values. There was no difference in LVQ values for myocardial infarction without tamponade and arrhythmic deaths. CONCLUSION: Based on the observation in our investigated cases, the phenomenon of post-mortem myocardial contraction cannot be explained by the influence of the investigated variables, except for pericardial tamponade cases. Further research addressing post-mortem myocardial contraction has to focus on other, less obvious factors, which may influence the early post-mortem phase too.