CT Contrast Studies Preparation

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Questions and Answers

Which of the following is a common purpose for abdominal CT imaging?

Detection of cardiac arrhythmias

Diagnosis of abdominal abnormalities (correct)

Assessment of brain activity

Evaluation of bone density

What is the required slice thickness for routine chest CT imaging?

5 mm

15 mm

10 mm (correct)

20 mm

Which of the following types of neoplasms is commonly associated with brain metastases in children?

Breast cancer

Lung cancer

Sarcomas (correct)

Melanoma

Which contrast administration route is frequently used in CT procedures?

Intravenous Signup and view all the answers

What is the typical slice thickness used for image reformation during CT scans?

1-2 mm Signup and view all the answers

What is the purpose of oral contrast in the initial study of the pancreas?

To improve the outlining of the gastrointestinal tract Signup and view all the answers

What is the required iodine contrast amount for evaluating a renal neoplasm?

30-40g of iodine Signup and view all the answers

Which imaging technique is mandated for evaluating a suspected renal neoplasm?

Both pre-and post-contrast images Signup and view all the answers

What is the recommended scan timing after the initiation of CM for renal imaging?

60 sec Signup and view all the answers

What is the key aspect evaluated during the assessment of images in imaging protocols?

Isocenter positioning and overall image quality Signup and view all the answers

What is the purpose of bolus administration in computed tomography?

To achieve maximum plasma iodine concentration and tissue enhancement Signup and view all the answers

What is a safe dilution percentage for oral or rectal water-soluble contrast media?

2-5% Signup and view all the answers

In a CT scan protocol for stroke, what type of scan is mandatory?

Routine plan of head without contrast Signup and view all the answers

What should be included in filming during a head CT scan for trauma?

Both brain parenchyma and bone windows Signup and view all the answers

Which is NOT a key point in evaluating CT images for neoplasms?

Type of contrast used during imaging Signup and view all the answers

How should contrast media be handled before administration to ensure patient safety?

Achieve a 2-5% dilution as found clinically useful Signup and view all the answers

What constitutes a completed stroke in clinical terminology?

Neurologic deficit lasting more than 21 days Signup and view all the answers

What is the significance of using thin slices in obtaining head CT scans?

To enhance visualization of the base of the skull Signup and view all the answers

Study Notes

Computed Tomography (CT) Contrast Administration

Bolus administration (manual or automatic) maximizes plasma iodine concentration and tissue enhancement.
Water-soluble contrast media alternatives include diatrizoate meglumine and diatrizoate sodium for GI tract opacification.
Careful preparation of water-soluble solutions is essential; 2-5% dilution is safe, while 15-40% may lead to hypovolemia.
Standard dilution involves mixing 20-30ml of contrast media in 1,000ml of solution (970ml of H2O).

CT Acquisition Protocol for Head/Neck, Thorax, and Abdomen

Head CT Scan Protocol

Used for post-traumatic abnormalities, suspected brain neoplasms, aneurysms, abscesses, atrophy, and metastases.
Trauma evaluation requires a plain study without contrast; thin slices (2-3mm) are necessary for base of the skull.
Include brain parenchyma and bone windows in imaging; follow-up studies may require contrast.

Stroke/CVA Protocol

Stroke ranks as the third leading cause of death in the US.
Terminology includes Transient Ischemic Attack (TIA), Reversible Ischemic Neurologic Deficit (RIND), and Completed Stroke.
Routine head CT plan (2-3mm for base, 10mm for brain) generally does not require contrast, except in traumatic cases.

Neoplasm Protocol

Primary CNS neoplasms occur at a rate of 5-6 per 100,000 adults; 20% of malignancies under 20 years are brain tumors.
Key evaluation points include lesion location, extent, and anatomical classification (intraaxial vs. extraaxial).

Pancreas Protocol

Initial study necessitates non-contrast imaging.
Scanning should begin at the iliac crest and move upward in 5mm intervals.
Involves a bolus IV injection of contrast (3ml/sec) and a 750-1000ml oral contrast solution.
For helical scanners, specific delays for arterial (30-35 sec) and venous phases (70 sec) are critical.

Kidney Protocol

CT is preferred for evaluating renal neoplasms; both pre- and post-contrast images are mandatory.
Pre-contrast images require 5mm increments; lesions <2cm necessitate 3-5mm contiguous sections.
Administer 30-40g of iodine (150-180ml) IV contrast bolus; scans taken after 60 seconds from diaphragm to kidney.

Image Assessment and Quality Control

Isocenter refers to the absolute center of the gantry; crucial for accurate imaging.
In-plane resolution denotes image resolution in the x-y direction.
CT scans provide detailed information on bone abnormalities, with thin slices (1-2mm) used for reformation.

Intracranial Metastatic Disease Protocol

Common parenchymal brain metastases originate from lung, breast, melanoma, and genitourinary and gastrointestinal tracts in adults; sarcomas and germ cell tumors in children.
Both plain and contrast-enhanced studies are recommended with specific bone and parenchyma windows.

Chest CT Scan Protocol

Acts as a diagnostic adjunct to radiography, useful for mediastinal lesions, aneurysms, abscesses, and cardiac diseases.
Requires contrast media, with various methods for administration; images typically taken in 10mm slice thickness.

Abdomen CT Scan Protocol

Recognized for speed and accuracy in diagnosing abdominal issues.
Abdominal CT is indicated for abnormalities affecting various organs including liver, pancreas, kidneys, adrenal glands, and pelvic tumors.
Reduction in use of ERCP and lymphangiography due to the effectiveness of abdominal CT.

Contrast Administration Essentials

Understanding types, dosages, purposes, and administration routes for common CT procedures is vital for optimal imaging outcomes.

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Description

This quiz covers the essential patient preparation for commonly performed computed tomography contrast studies. It focuses on the administration of oral and rectal contrast media, including water-soluble solutions. Understanding the impact of contrast on tissue enhancement and maximizing plasma iodine concentration is key for students in the medical field.