Radiology Course CT scan Ghione Emanuele Prof. Fabrizio Calliada

History CT was introduced in 1972 born from two separated research groups A.M.Cormack (american physicist) and G.N.Hounsfield (british electronic engineer) in the 60s Both won in 1979 the Nobel prize. … It is said that revenues from the sales of The Beatles records in the 1960s helped fund the development of the first CT scanner at EMI

Definition CT CT = Computed Tomography is a diagnostic technique which exploits ionizing radiations (X ray) It uses a computer that takes data from several X-ray images of structures inside a human's body and converts them into pictures on a monitor. Tomography is the process of generating a 2-dimensional image of a slice or section through a 3-dimensional object.

How is it made?

6

1) X ray rotating tube 7

2) Multiple rows of Detectors 8

3) The Gantry 9

4) The bed!!! (of course! :-) 10

What kind of images I can get? IT’S A SLICE!!!

2D coronal plan On the traditional radiogram in a single image represent the whole segment of the examined body Anatomic structures superimpose and may have no differences on density on the plain film. 13

CT scan - Body on slices 2D axial plan 14 All these projections are mathematically integrated to reconstruct a slice of the body. Every pixel of the image has an intensity corresponding to a density All the anatomic structures are visible without problems of superimposement The tissue density is measured with the Hounsfield units 2D axial plan 14

HOUNSFIELD UNIT 15

1 2 3 Evolution of CT scan Computed Axial Tomography (CAT scan) Spiral CT Multi-slice (multi-detector CT) 2 3

CAT (Computed Axial tomography) •Scanners were used to acquire sequential layers • They provided axial images of the han body "slices" of the human body • The exam is slow and complex

• CAT (computed axial tomography) • Spiral CT (single detector) • Computed tomography (CT Scan) • CAT (computed axial tomography) • Spiral CT (single detector) • Concept of body volume

Single slice One Rotation - One Image

• CAT (computed axial tomography) • Spiral CT (single detector) • Computed tomography (CT Scan) • CAT (computed axial tomography) • Spiral CT (single detector) • Multidetector CT (Multi Slice) • 16 layers • 64 layers • 128 layers • 600 layers

Multi slice One Rotation – Multiple Images

Multi slice

Contrast agent, or not contrast agent, that is the question… Brain / basal skull • vascular disease (ischemia-bleeding), trauma, infections. Brain / Skull with MDC • Vascular Pathology (study of intracranial vessels) • Pathology Oncology • Infectious pathology (abscesses) Abdomen baseline • Urinary stones Abdomen with MDC • Pathology of cancer parenchyma • Liver, pancreas, spleen, kidneys, adrenal glands • Vascular Pathology (study aorta; study mesenteric vasculature) • Pathology of the peritoneum • Pathology of the pelvis (oncology) Chest baseline • HRCT (high-resolution CT) Chest with MDC • Pathology of lung cancer (primary and secondary) • Vascular Pathology (study of the pulmonary vessels, study aorta) • Pathology heart (coronary study) Arterial and venous vascular system (only with MDC) • Arts • Aorta • Mesenteric vessels • Intracranial vessels

Brain CT Scan (without contrast)

Brain CT Scan (with contrast)

Lung CT Scan (without contrast) Pleural effusion Pericardic effusion

Lung CT Scan (with contrast) Lung carcinoma MDC

Abdomen CT Scan (without contrast) Kidney stones

Abdomen CT Scan (with contrast)

CT Scan CONTRAST PHASES Arterious - manual 10-30 sec - automatic 2) Venous or portal - 90 sec 3) Late or corticomedullary - 3-5 min

1) Arterious PHASE (ANGIO CT) how to make it - scan during transit of contrast media in artery

2) Venous PHASE How to make it for evaluation of the venous spleno-portal axis for evaluation of the parenchimas of the abdomen

3) Late - Corticomedullary PHASE Evaluation of kidneys, excretory system and urinary bladder washout of some tumors (e.g. HCC) Adrenal gland behaviour Better visualization of peripheral veins

Thank you!!!