The role of computed tomography in imaging
Computed tomography remains the cornerstone of imaging in oncology. The method is based on cross-sectional scanning of the body using X-rays.
In modern diagnostics, CT is not limited to simple anatomical evaluation. With the help of specialized software (such as computer-aided detection — CAD systems), effective screening can be performed. This is particularly relevant for detecting small pulmonary nodules and colorectal polyps.
Dynamic and spectral CT
Advancements in technology have led to the emergence of functional CT-based tissue evaluation methods:
- Dynamic contrast-enhanced CT — used for physiological imaging. It makes it possible to evaluate tumor perfusion and vascular network development (angiogenesis), which serves as an important cancer biomarker.
- Spectral CT (Spectral CT) — designed for better differentiation and precise characterization of tissue structures (especially in parenchymal organs such as the liver and kidneys). This technology is often implemented using dual-source scanners (Dual Source CT).
Methods of spectral CT implementation include the use of two radiation sources with different tube voltages (with two detectors), rapid voltage switching on a single source, pre-filtered dual beams, and multi-layer detectors sensitive to different radiation spectra.
The role of CT in a multimodal approach
Cross-sectional imaging methods (Cross-sectional imaging) serve as the basis for diagnosing neoplasms. Today, there is a shift from simple anatomical structure assessment to combining anatomical data with functional and molecular characteristics.
Computed tomography is frequently used as part of hybrid systems, such as PET/CT (PET/CT). In such systems, positron emission tomography provides targeted molecular imaging (e.g., assessing glucose metabolism using 18F-FDG), while CT provides precise anatomical localization of detected radiopharmaceutical uptake foci. The choice of a specific strategy is always individual and based on tumor type, clinical objectives, and cost-effectiveness.
Briefly: answers to topical questions
What radiopharmaceuticals are used for targeted molecular imaging in PET/CT?
Biomedical compounds labeled with fluorine-18, carbon-11, or oxygen-15 are used for targeted molecular imaging in PET/CT.
- 18F-FDG (fluorodeoxyglucose / FDG) — a glucose analogue used to evaluate glucose metabolism.
- 18F-FLT (18F-fluorothymidine / 18F-labelled 3-deoxy-3-fluorothymidine) — a thymidine analogue to evaluate cellular proliferation and growth.
- MET (L-[methyl-11C]methionine) — reflects amino acid transport and metabolism.
- Other radiopharmaceuticals — 18F- or 11C-choline, 11C-acetate, 18F-FMISO, 18F-FAZA, 61Cu-ATSM, 64Cu-ATSM.
What contrast phases are distinguished during dynamic liver CT?
During multiphase liver CT, four main contrast phases are distinguished.
- Unenhanced phase (unenhanced) — pre-contrast scanning.
- Arterial phase (arterial phase) — typically, the late arterial phase is used, in which the hepatic veins are not yet enhanced.
- Portal venous phase (portal phase) — the hepatic veins fill with contrast media and become radiopaque.
- Delayed phase (delayed phase) — used selectively for diagnosing specific lesions (e.g., hemangiomas and cholangiocarcinomas).
Early and late arterial phases may also be acquired during the study.
Class and exam questions
What are CAD systems used for in computed tomography?
These are computer-aided detection systems used for screening, for example, pulmonary nodules and colorectal polyps.
What clinical task is addressed using spectral CT?
Spectral CT improves the detection and characterization of various tissues and pathological lesions (e.g., in the liver or kidneys).
What does dynamic contrast-enhanced CT allow to evaluate?
This method helps evaluate physiological tumor parameters, specifically tissue perfusion and angiogenesis.
What else to study on this topic
- Magnetic resonance imaging (MRI)
- Physiological MRI sequences (DWI, DCE-MRI, BOLD)
- Positron emission tomography (PET) and radiopharmaceuticals
- Tissue acquisition methods: FNA and core-needle biopsy
- Biopsy instrumentation (Westcott-type needles)
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Computed tomography" and 2,199 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other topics in the "Diagnostic Radiology in Oncology" section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.