Multi-phase postmortem CT angiography (MPMCTA): a new axillary approach suitable in fatal thromboembolism

T1 mapping is useful for staging deep venous thrombosis in the lower extremities

BACKGROUND

The discrimination of acute and chronic deep venous thrombosis (DVT) is of great importance. Quantitative imaging is an urgent requirement in reflecting intrinsic characteristics of thrombosis.

PURPOSE

To investigate the feasibility of T1 mapping in staging DVT in the lower extremities.

MATERIAL AND METHODS

A total of 57 patients with DVT in the lower extremities (26 men, 31 women; mean age = 53.3 years) underwent T1-weighted imaging and T1 mapping for obtaining T1 signal intensity (SI) and T1 time of thrombus. The relative SI (rSI) of DVT was obtained by calculating the ratio of thrombus SI to muscle SI. The Mann-Whitney U test was used to compare rSI and T1 time of DVT between acute group (patients with limb edema ≤ 2 weeks) and chronic group (patients with limb edema > 2 weeks). A receiver operator characteristic (ROC) curve was constructed for further evaluation.

RESULTS

DVT rSI was significantly higher in the acute group versus the chronic group (2.8 ± 1.2 vs. 1.4 ± 0.6; P<0.05). DVT T1 time was significantly lower in the acute group versus the chronic group (819.4 ± 223.7 ms vs. 1264.8 ± 270.7 ms; P<0.05). The area under the curve (AUC) was 0.93 for T1 time and 0.75 for rSI. When using 1015 ms as the cut-off, the sensitivity and specificity of T1 time were 91% (32/35) and 86% (19/22), respectively.

CONCLUSION

T1 mapping is a potential technique in discriminating acute from chronic DVT in the lower extremities and warrants further investigation.

Role of 3D Volumetric and Perfusion Imaging for Detecting Early Changes in Pancreatic Adenocarcinoma

Purpose

There is a major shortage of reliable early detection methods for pancreatic cancer in high-risk groups. The focus of this preliminary study was to use Time Intensity-Density Curve (TIDC) and Marley Equation analyses, in conjunction with 3D volumetric and perfusion imaging to demonstrate their potential as imaging biomarkers to assist in the early detection of Pancreatic Ductal Adenocarcinoma (PDAC).

Experimental Designs

A quantitative retrospective and prospective study was done by analyzing multi-phase Computed Tomography (CT) images of 28 patients undergoing treatment at different stages of pancreatic adenocarcinoma using advanced 3D imaging software to identify the perfusion and radio density of tumors.

Results

TIDC and the Marley Equation proved useful in quantifying tumor aggressiveness. Perfusion delays in the venous phase can be linked to Vascular Endothelial Growth Factor (VEGF)-related activity which represents the active part of the tumor. 3D volume analysis of the multiphase CT scan of the patient showed clear changes in arterial and venous perfusion indicating the aggressive state of the tumor.

Conclusion

TIDC and 3D volumetric analysis can play a significant role in defining the response of the tumor to treatment and identifying early-stage aggressiveness.

Pulmonary PMCT angiography by right ventricle cardiac puncture: a novel, promising approach for investigating pulmonary thromboembolism

Forensic scholars are paying more attention to postmortem computed tomography (PMCT) and PMCT angiography (PMCTA), which are gradually becoming effective and practical methods in forensic practice. However, few studies have focused on the application of PMCTA to cardiac ventricular puncture-especially of the right ventricle. In this article, we introduce a pulmonary PMCTA approach by right ventricle cardiac puncture and its potential value in fatalities from pulmonary thromboembolism (PTE). The procedure was performed on 11 males and 6 females. PMCT was performed first; then a biopsy core needle was used for percutaneous puncture of the right ventricle under CT guidance. About 400 mL of contrast media was injected at a rate of 50 mL/8 s, followed by CT scanning. Visualization of the pulmonary artery contrast filling was complete in 9 cadavers, and the pulmonary arteries showed significant filling defects in 8 subjects. Unlike in clinical practice, the phenomenon of postmortem coagulation sometimes occurs in the vascular lumina after death. Therefore, the results of these 8 cases can only suggest or be highly suspicious of death from PTE. Then autopsy and histopathological examination confirmed that 4 of the above 8 patients were diagnosed with PTE; the remaining 4 had postmortem clot including chicken fat clot in the pulmonary artery. Pulmonary PMCTA approach is a simple, convenient, and effective method for the visualization of the pulmonary artery, which can be used as an effective auxiliary tool to identify PTE in forensic practice. It will also provide technical support to further investigate PTE imaging characteristics.

Diagnosing coronary thrombosis using multiphase post-mortem CT angiography (MPMCTA): A case study

While post-mortem angiography (PMA) is gradually establishing its role in Forensic Radiology, the available literature in Italy lacks a solid foundation, particularly regarding its use in criminal court proceedings. An illustrative example of multiphase post-mortem CT angiography (MPMCTA) is presented here to encourage the systematic implementation of PMA methods. To demonstrate concordance between MPMCTA and the reference standard (autopsy and histology) in a case of acute coronary thrombosis, we report a case where MPMCTA, autopsy, histological and toxicological analyses were performed on a previously healthy 51-year-old man. MPMCTA detected a right coronary artery filling defect that could be ascribed to coronary thrombosis, which was later confirmed by autopsy and histological examinations.

Evolution of post-mortem coronary imaging: from selective coronary arteriography to post-mortem CT-angiography and beyond

Since the 1970s, remarkable efforts have been made in the post-mortem coronary study, especially by angiography, as an added tool to diagnose heart-related deaths. In more recent times, post-mortem CT (PMCT) and post-mortem CT-angiography (PMCTA) have become an established practice in numerous forensic units, because of the undeniable advantages these diagnostic instruments can offer: data acquisition times are increasingly fast, costs have become lower and, once acquired, data can be re-utilized and re-evaluated at any given time. This review aims to chart the history of post-mortem cardiac imaging, highlighting its evolution both in terms of methodology and technology as well as the contribution that forensic radiology has been able to offer to forensic pathology, not as an alternative to autopsy but as a guide and aid when performing one. Finally, the latest advances in the study of cardiac deaths are explored, namely by cardiac post-mortem MRI (PMMR), able to visualize all the various stages of a myocardial infarction, post-mortem MRI-angiography (PMMRA), useful in investigating coronary artery pathology and post-mortem cardiac micro-CT, able to provide near-histological levels of myocardial, coronary and valvular detail.

Forensic Radiology: An Update

Forensic radiology is a specialized area of medical imaging using radiological techniques to assist physicians and pathologists in matters related to the law. The forensic application of diagnostic medical radiology can be applied in many fields; the prime target of evaluation is the osseous skeleton, but soft tissues and abdominal and thoracic viscera may offer key findings. The technological progress in clinical radiology provides a lot of potential tools to forensic radiology, allowing wider fields of applications in this matter.

Medico-Legal Aspects of Pulmonary Thromboembolism

Pulmonary ThromboEmolism (PTE) is an important disease for legal medicine. Because of their sudden lethal onset, generally medicolegal autopsies show few clinical information when PTE is the cause of death. During medicolegal autopsies, the autopsy operator must answer to important questions. For example, autopsy operator can need to assess the casual relationship between PTE and recent accident, such as trauma or long air travel. Furthermore, the autopsy operator needs to investigate the pathology of PTE as a cause of sudden cardiovascular death. It is relatively simple to confirm a fatal massive thromboembolus in the initial stage of thoracic investigations, but sometimes it might be difficult to distinguish this from postmortem clot. In such cases histopathological examination can help in the differentiation. Histological examination is also required for observation of chronological changes of the thrombi. Chronological evaluation is an important factor especially to determine whether the death coincides with the date of a specific accident/event or instead there is an earlier onset of PTE. In addition, histological sections sometimes show additional information, such as tumor fragments in cases of malignancy or small fragments of bone marrow in cases of active resuscitation, that can be useful in a medicolegal scenario. Furthermore, new diagnostic tools are arising, which they can be very helpful in the individuation of this frequently underdiagnosed disease. The goal of our work is to investigate these aspects through the review of the recent literature.

Modern post-mortem imaging: an update on recent developments

Modern post-mortem investigations use an increasing number of digital imaging methods, which can be collected under the term "post-mortem imaging". Most methods of forensic imaging are from the radiology field and are therefore techniques that show the interior of the body with technologies such as X-ray or magnetic resonance imaging. To digitally image the surface of the body, other techniques are regularly applied, e.g. three-dimensional (3D) surface scanning (3DSS) or photogrammetry. Today's most frequently used techniques include post-mortem computed tomography (PMCT), post-mortem magnetic resonance imaging (PMMR), post-mortem computed tomographic angiography (PMCTA) and 3DSS or photogrammetry. Each of these methods has specific advantages and limitations. Therefore, the indications for using each method are different. While PMCT gives a rapid overview of the interior of the body and depicts the skeletal system and radiopaque foreign bodies, PMMR allows investigation of soft tissues and parenchymal organs. PMCTA is the method of choice for viewing the vascular system and detecting sources of bleeding. However, none of those radiological methods allow a detailed digital view of the body's surface, which makes 3DSS the best choice for such a purpose. If 3D surface scanners are not available, photogrammetry is an alternative. This review article gives an overview of different imaging techniques and explains their applications, advantages and limitations. We hope it will improve understanding of the methods.

Postmortem-computed tomography and postmortem-computed tomography-angiography: a focused update

The use of multidetector CT (MDCT) represents a reality routinely used in several forensic institutes, for the numerous advantages that this diagnostic tool can provide; costs are becoming increasingly lower; data acquisition is always faster and once acquired may be revalued at any time. However, there are also some diagnostic limitations, for example, the visualization of the vascular system or a limited soft tissue contrast. In order to overcome these limitations, in recent years, contrast medium has been introduced in postmortem cases, with the development of several techniques of PMCT angiography (PMCTA) and standardized protocols to make them easily reproducible. The aim of this review is to highlight the advantages and pitfalls of PMCT and PMCTA in forensic investigation, taking into consideration the broad spectrum of applications both for natural and unnatural deaths and the numerous methods currently used. Secondly, in the light of the considerable progress in this field and the attempt to develop standardized protocols of PMCTA, the authors aim to evaluate the diagnostic value of PMCTA in comparison both to PMCT and conventional autopsy.

Application of contrast media in post-mortem imaging (CT and MRI)

The application of contrast media in post-mortem radiology differs from clinical approaches in living patients. Post-mortem changes in the vascular system and the absence of blood flow lead to specific problems that have to be considered for the performance of post-mortem angiography. In addition, interpreting the images is challenging due to technique-related and post-mortem artefacts that have to be known and that are specific for each applied technique. Although the idea of injecting contrast media is old, classic methods are not simply transferable to modern radiological techniques in forensic medicine, as they are mostly dedicated to single-organ studies or applicable only shortly after death. With the introduction of modern imaging techniques, such as post-mortem computed tomography (PMCT) and post-mortem magnetic resonance (PMMR), to forensic death investigations, intensive research started to explore their advantages and limitations compared to conventional autopsy. PMCT has already become a routine investigation in several centres, and different techniques have been developed to better visualise the vascular system and organ parenchyma in PMCT. In contrast, the use of PMMR is still limited due to practical issues, and research is now starting in the field of PMMR angiography. This article gives an overview of the problems in post-mortem contrast media application, the various classic and modern techniques, and the issues to consider by using different media.