The radiologist has the essential task of providing an adequate diagnosis and classification of a splenic injury in order to refer the patient to a conservative treatment or to a surgical one.

The poly-injured patient’s radiological study is different according to the dynamics of trauma and their clinical conditions upon arrival at the emergency room.

US and CT have a key role in the management of blunt abdominal trauma. Studies have shown that US has sensitivity of 97% and specificity of 100% in predicting the presence of hemoperitoneum: in fact, US is the first choice technique for early screening, allowing to demonstrate the presence of hemoperitoneum in which patients that are hemodynamically unstable, and refer them to embolization or surgery [15]. Ultrasound should be the initial investigation of choice when examining children or in young woman [16]. However, US has low sensitivity in diagnosing an organ injury [17]. Over the last few years, with the introduction of Contrast Enhanced UltraSonography (CEUS) the sensitivity is greatly increased, with 96% sensitivity and 99% specificity rates compared to CT. CEUS shows a high sensitivity both in lesion detection and grading [18, 19] but it has a lower accuracy in the evaluation of prognostic factors; CEUS plays an important role also in blunt abdominal trauma in pediatric patients [20–22]. CT is undeniably the gold standard for the identification, diagnosis, and staging of abdominal organs in trauma patients: CT also shows all non-parenchymal organ lesions that US and CEUS are not capable of detecting. CT must always be performed in CEUS-positive patients to exclude active bleeding [23].

Computed tomography (CT) is the gold standard for patient evaluation in case of blunt injury and for the detection and staging of splenic lesions.

This technique is widely used in Emergency Radiology Departments, due to increasing diffusion of multi-detector CT (MDCT) and because it’s able to meet the main targets of Emergency Surgery which are early lesion identification, the assessment of the presence of hemoperitoneum and any further injury in whole body. Computed tomography study, due to its panoramicity, allows to identify any damage to every organ beyond the spleen. The aim of a correct and prompt diagnosis is to refer the patient to a surgical or conservative treatment, already in the acute phase, and avoid the misdiagnosis of the most insidious injuries, that may show signs only hours or days later.

In a patient with left-quadrant isolated trauma, after US and CEUS, CT can be used as a second choice, to clarify any questionable sonographic findings [16]; instead in a poly-traumatized hemodynamically stable patient, MDCT is the first choice and helps in differentiation of patients with active splenic bleeding (who risk hemorrhagic shock and which could indicate a need for surgery or embolization) from patients with stable non-bleeding injuries, who are candidates for conservative management, with the valuation of vital parameters and a close follow-up, to reduce surgical morbidity and preserve immune competence [24].

Total-body MDCT is always performed in basal phase and after intravenous administration of contrast, with dual-phase (acquisitions in the arterial and portal-venous phases): it is vital that the amount of contrast is adequate and customized to the patient’s weight, and that the flow must be high, because those parameters greatly influence the quality of the examination.

The multiphasic protocol provides a better overall diagnostic tool for the evaluation of the splenic lesions: in particular, the arterial phase is more sensitive for the evaluation of vascular injury including active bleeding and vascular lesions, while the portal-venous phase is better for the illustration of parenchymal damage. Several types of splenic injury can occur: intraparenchymal and subcapsular hematoma, contusion, laceration, active extravasation, and contained vascular injury [25]. Clotted blood has an attenuation of approximately 45–70 Hounsfield Units (HU); it is better seen in basal phase as a slightly hyperdense area, while unclotted blood has an attenuation of 30–45 HU.

According to Marmery, the splenic lesion is classified from Grade 1 to Grade 3, and the grade increases according to the depth of the laceration [14, 27]. Concerning vascular lesions, this classification adds grade 4 injury, that is divided into subgroups: 4a and 4b. In fact, a laceration that compromises the vascularization of the spleen (vascular hilar damage) coincides with a severe injury (Grade 4). A contrast-medium extravasation is an active sign of bleeding, which can be subcapsular/parenchymal (Grade 4a) (Fig. 16.11) or endo-peritoneal/peri-splenic (Grade 4b) (Fig. 16.12) and almost always requires immediate surgical treatment. When the exam detects a bleeding, a vascular study is essential, as it allows to detect focal areas of high attenuation, which often is evident in the arterial phase and then spreads in portal-venous phase, this change in morphology allows to make a differential diagnosis between active bleeding and a contained vascular lesion (such as pseudoaneurysm and arteriovenous fistula) that does not change in its morphology. On single-phase scanning, it can be difficult to differentiate active extravasation from contained vascular injury; however, on equilibrium phase scans, an area of active extravasation will remain hyperdense and enlarged, whereas a contained vascular injury will typically “wash out” and be isodense or slightly hypodense relative to splenic parenchyma (Fig. 16.13). These contained vascular lesions are recognized as a well-defined margin in intraparenchymal areas, with high attenuation in arterial phase and isodensity in portal-venous phase (Fig. 16.14). The distinction between fistula and post-traumatic pseudoaneurysm is easier to identify with arteriography. In the pseudoaneurysm there is a tear in the artery, but bleeding is typically limited by the arterial adventitia.

Active bleeding increases in size on delayed-phase images unlike a contained vascular lesion [14]. Pseudoaneurysm and arteriovenous fistula are conditions predisposing a late-breaking spleen and typically are managed through embolization. Pseudoaneurysm breaks in a percentage that ranges from 3 to 46% of cases.

When the capsule is break, typically, hemoperitoneum is associated. According to the Federle semi-quantitative scale [28], hemoperitoneum is divided into small (when the blood is in only one endo-peritoneal space, as the peri-splenic, peri-hepatic, in the parieto-colic or Morrison spaces, with an estimated blood loss of about 250–500 mL) or large (with blood effusion in two or more endo-peritoneal/pelvic spaces, with blood extravasation greater than 500 mL) (Fig. 16.12).

Ultrasonography is used first in hemodynamically stable patients with minor trauma, because it is easy to perform, quick, affordable, and noninvasive. However, even in expert hands, basic US has too low sensitivity to diagnose organ injuries (no more than 50%) especially in case of spleen injury because the “fresh blood” has similar echogenicity as a recent parenchymal lesion. For this reason, CT was used excessively over the years so as not to miss potentially dangerous splenic injuries [3].