Postprocessing Imaging Techniques of the Computed Tomography Angiography in Trauma Patients for Preprocedural Planning

Computed tomography provides a wealth of diagnostic information in the trauma patient including the presence of organ, bone, and vasculature injuries for the rapid triage of trauma patients. In the context of interventional radiology, appropriately protocoled studies can be reviewed for vascular injury and help focus the angiographic assessment of bleeding patients to ideally achieve earlier hemostasis. This article outlines various image-processing techniques such as multiplanar reformats, curved planar reformats, maximum intensity projections, and volume rendering to identify and more thoroughly characterize vascular injuries as a preprocedural planning tool to expedite endovascular hemostasis in a case-based format.

Foot Trauma

Chapter 24 reviews the mechanism of injury, imaging strategy, imaging characteristics, and treatment of foot trauma including the calcaneus, talus, navicular, Lisfranc joint, metatarsals, and phalanges. Classification of fractures and associated injuries are also discussed. Radiographs should be performed first in the evaluation of foot trauma. Standard views of the foot are anterior-posterior (AP), lateral and oblique. CT with multiplanar reformats is commonly used for preoperative assessment of calcaneal fractures and can show tendon entrapment. CT examination is also frequently performed for talar head, neck and body fractures for presurgical planning to assess the degree of displacement, joint reduction, comminution and intraarticular involvement.

Computed tomography

Computed tomography (CT) has increased in use exponentially for the assessment of patients with renal tract pathology. This has been promoted by the availability of multidetector thin-slice CT so that intravenous urography has been superseded by CT urography. The latter may be considered as a ‘one-stop’ imaging investigation for haematuria, with increased detection of both urinary tract cancers and urolithiasis. Multiplanar reformats are made possible with the use of thin slices, allowing clear delineation of other pathologies such as urinary tract injury. In the transplant recipient, protocols have been developed for the assessment of more immediate complications such as thrombotic and stenotic disease. During follow-up, CT continues to inform the management of post-transplant lymphoproliferative disorder and other immunosuppressant-related complications. Unenhanced CT of the urinary tract has established its role in assessment of patients with renal colic, with the ability to detect pathology outside of the urinary tract. Renal CT has been developed for the characterization of renal masses, accompanied by the now well-established Bosniak renal cyst classification system. As the usefulness of CT increases, clear awareness of safety issues has to be maintained. These include the administration of intravenous iodinated contrast medium in higher-risk patient groups, particularly those with renal impairment. The radiation burden that comes with CT poses an added risk to the patient that should not be ignored. This necessitates clear referral guidelines for its use, which should be applied in careful balance with the global assessment of the patient.

Identification of Cardiac and Aortic Injuries in Trauma with Multi-detector Computed Tomography

Blunt and penetrating cardiovascular (CV) injuries are associated with a high morbidity and mortality. Rapid detection of these injuries in trauma is critical for patient survival. The advent of multi-detector computed tomography (MDCT) has led to increased detection of CV injuries during rapid comprehensive scanning of stabilized major trauma patients. MDCT has the ability to acquire images with a higher temporal and spatial resolution, as well as the capability to create multiplanar reformats. This pictorial review illustrates several common and life-threatening traumatic CV injuries from a regional trauma center.

Measurement of Carotid Stenosis on Computed Tomographic Angiography: Reliability Depends on Postprocessing Technique

Purpose We previously demonstrated the validity of axial source (AxS) image quantification of computed tomographic angiography (CTA) visualized carotid stenosis. There is concern that AxS images may not accurately measure stenosis in patients with obliquely orientated stenosis and that measurements on axial oblique (AxO) multiplanar reformats (MPR), maximum intensity projections (MIP) images, or Doppler ultrasound (DUS) are superior. We tested the performance of AxS images against AxO MPRs, MIPs, and DUS techniques for stenosis quantification. Methods A total of 120 consecutive patients with CTA and DUS detected carotid disease were enrolled; carotids with occlusion, near occlusion, or stenosis <40% were excluded. Proximal and distal carotid diameters and North American Symptomatic Carotid Endarterectomy Trial (NASCET) style ratios were measured independently by 2 neuroradiologists on AxS, AxO, and MIP images on separate occasions in a blinded protocol. Intra- and interobserver agreements were determined for all measurements. The performance of different image types to identify ≥70% stenosis was assessed against a NASCET-style reference standard. Results Intra- and interobserver reliabilities for stenosis measurements were higher for both AxS (interclass correlation coefficients [ICC], 0.87–0.93 and 0.84–0.89) and AxO images (ICCs, 0.82–0.89 and 0.86–0.92) than for MIPs (ICCs, 0.66–0.86 and 0.79–0.82), respectively. Intra- and interobserver agreements on the NASCET ratio tended to be lower than proximal stenosis measurements. AxS and AxO image proximal stenosis measurements most accurately distinguished patients with ≥70% stenosis (0.90), followed by DUS (0.83) and MIP images (0.76). Conclusions A single AxS image stenosis measurement was highly reproducible and accurate in the estimation of carotid stenosis, which precluded the need for AxO MPRs.