Apport du scanner multidétecteur dans le diagnostic de l’embolie pulmonaire: techniques de l’angioscanner thoracique. F. Fadhlaoui, M. Grissa, M. Souei. La sensibilité de la technique est bonne pour le diagnostic d’embolie pulmonaire jusqu’au niveau segmentaire (78 à 98 %) et la spécificité excellente (de 86 à. Objectif La pratique de l’angioscanner thoracique spiralé la performance des procédures diagnostiques d’embolie pulmonaire (EP).
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With a mortality rate at approximately 25 percent, pulmonary embolism PE is one of the leading causes of maternal death during pregnancy and pu,monaire. Moreover, foetuses are especially sensitive to dose. Over-diagnosis may also result in treatments that might be dangerous for the unborn child and the mother.
Evolution falsely relieving of angio scanner in the follow up..|INIS
Lastly, conventional imaging modalities are more complicated when used for pregnant patients. When PE is suspected, a computed tomography CT scan may be recommended in some countries as a quick response. Diagnosing cases of PE presents particular challenges, however; pregnancy-related physiological changes have the potential to impair image quality to such an extent that a diagnosis may no longer be possible.
Not only is CTPA usually readily available, it also enables comprehensive assessment of the thorax and visualization of the thrombus to support differential diagnoses Fig.
During CTPA, radiologists and radiographers subjectively evaluate injection quality to check for sufficient contrast enhancement of the pulmonary arteries. Objective evidence would be when a region of interest ROI placed at the pulmonary artery indicates a density higher than HU. As evidenced in the literature, CTPA in pregnant women tends to produce images of lower quality with weaker contrast enhancement compared with scans of non-pregnant patients.
This reduced quality of CTPA in pregnant women is caused almost entirely by pregnancy related physiological changes that can last for several weeks postpartum.
Researchers conducted a survey to find out whether other imaging facilities had a specific protocol for CT pulmonary angiography in pregnant women and how satisfied they were with the quality of these types of examinations. Results showed that very few institutions had a specific protocol and levels of satisfaction varied widely. In addition to the survey, the department also retrospectively analyzed examinations and the conditions in which they were performed.
The researchers identified four fundamental factors that could improve contrast enhancement of the pulmonary arteries during CT angiography in pregnant women: Prohibition of deep inspiration to prevent the Valsalva Maneuver, low voltage scan, appropriate injection volume and rate, and early acquisition.
As a result, they proposed adjustment of these four parameters to improve pulmonary arterial contrast enhancement and, therefore, image quality. In the following, we will take a closer look at these four parameters.
Pulmonary Embolism Diagnosis in Pregnancy: How Bicêtre Hospital Overcomes Imaging Challenges
This is known as the Valsalva Maneuver. It almost completely dilutes the contrast agent coming from the angioscsnner vena cava SVC. Voltage affects image quality, particularly when contrast is involved.
When voltage is decreased, the photoelectric effect dominates and contrast increases. Conversely, when voltage is increased, the dominant Compton Effect reduces contrast. Moreover, lowering kV from to also considerably reduces radiation, given that the dose delivered to the patient is proportional to the square of the voltage at an identical mAs.
This remarkable speed means that time is now also a key factor in pulmonary imaging. Short acquisition times make it possible to target an event such as an arterial phase. The disadvantage is that if the acquisition window misses the point of maximum enhancement, the arteries will not be fully opacified and it becomes difficult to rule out pulmonary embolism.
This is why timing is considered so important: In the case of pregnancy, the increased speed of blood flow requires an earlier acquisition that starts when the superior vena cava is opacified vs the opacification of the pulmonary trunk in the general population. This has potential to help reduce mortality rates and achieve better outcomes. With the improved diagnostic image quality, PE could also potentially be ruled out faster allowing patients to possibly be discharged sooner and given peace of mind.
For further information, please refer to the original article: Embolie Pulmonaire et Grossesse. Ann Fr Anesth Reanim.
Grossesse et embolie pulmonaire: Mescape, Aug 09, Prise en charge des principales urgences thoraciques et abdominales durant la grossesse. Quality of CT pulmonary angiography for suspected pulmonary embolus in pregnancy. Does pregnancy affect vascular enhancement in patients undergoing CT pulmonary angiography?
CTPA for the diagnosis of acute pulmonary embolism during pregnancy. Pulmonary CT angiography protocol adapted to the hemodynamic effects of pregnancy. Measurement of caval blood flow with MRI during respiratory maneuvers: Thorac Imaging ; 22 2. Image quality and radiation exposure at angioscxnner CT angiography with or kVp protocol: Feuillets de Radiologie ; 47 3: Pulmonary Embolism Diagnosis in Pregnancy: Overcoming CT imaging limitations.