Imaging Pearls ❯ Trauma ❯ CTA
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- “CTA is a frequently used first-line imaging study for the assessment of peripheral vascular trauma. CTA is usually readily available in emergency settings where trauma protocol CTs of the chest and abdomen are performed and is often faster and prone to less iatrogenic complications than conventional an- giography. Multiple specific manifestations of vascular trauma are readily demonstrated on CTA, which guide the next steps in patient management. Identification of these imaging signs is important to prevent devastating complications of vascular injury.”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152 - "CTA is now widely accepted as the first-line imaging investigation when an upper or lower extremity vascular injury is in question. Compared with conventional angiography, CTA has the advantages of being less invasive, more readily avail- able, and allowing for the evaluation of the adjacent soft tissues and bones. CTA avoids potential iatrogenic complica- tions associated with catheter angiography, such as pseudoaneurysm, hematoma, thrombosis of the access vessel, and peripheral embolization. CTA is also less expensive and can be obtained quickly, as opposed to the delay often required to assemble a specialized team to perform conventional angiography, a particular advantage of CTA when reducing ischemic time is known to be an important factor in limb salvage.”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152 - "Analyses of trauma patients who underwent upper or lower extremity CTA showed sensitivities in the range of 95–100%, specificities of 87–100%, a low nondiagnostic imaging rate, and good inter-observer agreement between radiologists indicating that CTA can replace conventional diagnostic angiography in the acute trauma setting. Several of these studies are limited by verification and follow-up bias, and although some injuries may have been missed by CTA, none of the missed injuries was likely to have been clinically significant”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152 - "When unilateral upper extremity CTA is to be performed, an IV should be placed contralateral to the affected extremity to prevent dense venous contrast from obscuring the adjacent arteries. Optimal positioning is with the body supine with the arm over the head, palm facing upward with fingers extended. If more comfortable for the patient, prone body position- ing with the palm facing the table is also acceptable. Positioning the arm above the head helps to reduce noise; however, this may not be possible in the setting of an upper extremity injury. In such cases, the arms can be positioned at the patient’s side with images acquired in the same field-of- view as the chest, abdomen, and pelvis CT.”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152 - "Multiplanar reconstructions in the coronal and sagittal planes are performed at the scanner. Curved planar reconstructions (CPR) and maximum intensity projection (MIP) images can be constructed at the workstation. 3D renderings produced at the workstation or in a dedicated 3D lab are offered upon ordering provider request. Vascular structures are usually best viewed with window width setting around 600 and window level setting around 80.”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152 - “A pseudoaneurysm is an injury to the artery contained by fibrous tissue or adventitia, which is in contrast to true aneurysms which contain all three layers of the vessel wall. On CTA, a pseudoaneurysm will appear as a focal contrast-filled outpouching .In contrast to active hemorrhage, pseudoaneurysms maintain their shape on delayed phase imaging, whereas contrast will increase and change shape in the setting of active hemorrhage. Occasionally, the outpouching will not entirely fill with contrast owing to the presence of thrombus. Sometimes pseudoaneurysm can have delayed presentation with atypical clinical symptoms such as compressive neuropathy or pulsatile soft tissue mass.”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152 - "An AVF occurs when traumatic injury results in a direct communication between an artery and an adjacent vein without an intervening capillary bed. The exact site of communication may not be visible; however, early filling of a vein adjacent to an artery in the region of traumatic injury (in the absence of venous filling in the more distal extremity) is indicative of an AVF.”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152 - “Arterial vasospasm occurring in the setting of traumatic injury can be difficult to differentiate from dissection with a thrombosed false lumen. The etiology of vasospasm in the absence of visible endothelial injury is not entirely clear, but has been hypothesized to be related to mechanical stimulus from pressure waves transmitted from a high velocity pene- trating object and/or release of vasoconstrictive substances. Like other types of arterial injury, vasospasm is usually present adjacent to soft tissue injury or vessel segments along the path of the penetrating injury and appears as a narrowed segment of the artery. Management depends on the severity and length of the narrowed segment, but may include conventional angiography, MR angiography, or clinical monitoring with follow-up imaging to ensure resolution and differentiate from a true arterial injury.”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152 - "Variant vascular anatomy can be a potential source of false positives results. If an artery does not arise at its conventional location, it may be mistaken for an occlusion. In a study of conventional arteriograms of the upper extremity, variants were noted in 9% of individuals, the most common being a high origin of the radial artery from the brachial artery, with high origins of the radial and ulnar artery from the axillary artery occurring less frequently. In the lower extremity, approximately 9% of individuals have variant popliteal and tibial artery branching patterns, with high origins of the anterior tibial artery being most common. In addition, the tibial arteries may be congenitally absent or hypoplastic, and in these cases should not be confused with occlusion. Findings that suggest a congenitally absent or hypoplastic tibial artery include robust remaining tibial arteries supplying the extremity in the region of the absent artery, finding present on a prior imaging study, lack of abrupt vessel cutoff, and extended distance from region of trauma.”
Imaging primer for CT angiography in peripheral vascular trauma
Lara Walkoff et al.
Emergency Radiology (2021) 28:143–152
- “CTA of the lower extremities is an important and versatile noninvasive tool for diagnosis as well as surgical or endovascular interventional planning. Although lower extremity CTA is most commonly performed in patients who suffer from PAD or trauma affecting the lower extremities, it also plays a role in the workup of nonischemic etiologies and congenital vascular malformations. CT scanner protocols should adjust bolus timing and multi- phasic imaging to account for the clinical question of interest, and 3-dimensional postprocessing plays an important role in the visualization and interpretation of these high-resolution imaging examinations.”
Computed Tomography Angiography of the Lower Extremities Cook TS Radiol Clin N Am 54 (2016) 115–130 - “Trauma to the lower extremities can occur from blunt or penetrating causes. Blunt trauma includes motor vehicle collisions, falls, athletic injuries, and occupational injuries, and is often associated with severe pelvic, femoral, and/or tibial fractures. Penetrating trauma may occur secondary to ballistics, shrapnel, or low-velocity sharp objects, and may or may not affect the bones of the extremity depending on the trajectory of the ballistic missile. Arterial injury in the setting of trauma may result in active extravasation, subcutaneous or intramuscular hematoma, pseudoaneurysm, vessel narrowing/stretching, occlusion, or arteriovenous fistula.”
Computed Tomography Angiography of the Lower Extremities Cook TS Radiol Clin N Am 54 (2016) 115–130
- “ In this article, we discuss potential indications for whole body CT angiography, the benefit of reviewing multiplanar reformation (MPR) and three dimensional (3D) images for timely and accurate interpretation.”
Blunt Polytrauma: Evaluation with 64-Section Whole-Body CT Angiography
Dreizin D, Munera F
RadioGraphics 2012; 32:609-631 - “ Acquisition of subisotropic voxels confers nearly equivalent resolution in any plane and provides many opportunities for maximizing efficiency in evaluating for injuries in patients with blunt polytrauma, necessitating a move away from overreliance on axial images; thus, the use of coronal and sagittal images should no longer be considered complimentary.”
Blunt Polytrauma: Evaluation with 64-Section Whole-Body CT Angiography
Dreizin D, Munera F
RadioGraphics 2012; 32:609-631