**Question:** Non-contrast spiral CT is investigation of choice for

A. Abdominal trauma
B. Acute ischemic stroke
C. Thoracic trauma
D. Acute stroke evaluation

**Correct Answer:** C. Thoracic trauma

**Core Concept:** Non-contrast spiral CT is a type of computed tomography (CT) scan that uses a combination of rapid X-ray rotation and computer processing to create detailed images of internal organs and structures. It is a valuable diagnostic tool in medicine, particularly in emergency situations where rapid assessment is crucial.

**Why the Correct Answer is Right:** Non-contrast spiral CT is particularly useful in evaluating thoracic trauma patients, as it allows for detailed assessment of the lungs, heart, mediastinum, and chest wall without the potential hazards of contrast media in certain patient populations. This type of CT scan allows for early detection of life-threatening complications, such as pneumothorax, hemothorax, and aortic injury.

**Why Each Wrong Option is Incorrect:**

A. Abdominal trauma: While CT scans are generally used for abdominal trauma evaluation, non-contrast spiral CT may not be the first choice, especially considering the risks of iodinated contrast media in some patients. Other imaging modalities like ultrasound or plain films may be more suitable in certain cases.

B. Acute ischemic stroke: CT scans, including non-contrast spiral CT, are essential in stroke evaluation, but they are not the primary choice for acute ischemic stroke assessment. Magnetic resonance imaging (MRI) is often preferred due to its superior soft tissue resolution and lack of ionizing radiation exposure.

D. Acute stroke evaluation: Similar to option B, while CT scans are valuable in stroke evaluation, non-contrast spiral CT may not be the first choice due to its lower soft tissue resolution compared to MRI.

**Clinical Pearl:** In emergency situations, a combination of clinical assessment, non-contrast CT, and MRI can be used to cover all aspects of stroke evaluation, ensuring comprehensive diagnosis and treatment. However, it is essential to consider the patient's specific condition and contraindications to MRI before deciding on the imaging modality.