Introduction To Radiology

1 INTRODUCTION TO RADIOLOGY I. DIAGNOSTIC X-RAY X -rays are useful: • In diagnosis of diseases involving bones, lungs, gut, kidneys & gall bladder • In CT- scan , Mammography • In detecting the congenital, inflammatory, traumatic, degenerative & neoplastic disease PLAIN STUDY • Certain diseases need only plain X-rays for diagnosis e.g. in bone, lungs, intestines, kidneys & gall bladder stones. RADIO-OPAQUE/DENSE • Infiltrate / inflammatory process • Mass / tumor • Fluid • Lithiasis • Foreign body e.g. coin RADIOLUCENT • Pneumoperitoneum • Pneumothorax • Pneumomediastinum • Pneumopericardium • tumor Fluoroscopy Contrast examination Contrast (barium / iodine ) • Contrast is given orally / IV /other routes depending upon region ( part ) under investigation. - Upper gastrointestinal series (UGIS) o To evaluate the esophagus, stomach, duodenal bulb and the prox small bowel segments

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Small intestinal series (SIS) o To evaluate the small bowel segments BARIUM ENEMA (BE) o To evaluate the colonic segments IVP o Intravenous contrast for functional & structural assessment of kidneys. Hysterosalpingogram studies o To evaluate uterus & tubes of infertile women Angiogram study o To evaluate the lumen of blood vessels

II. ULTRASOUND Advantages • No radiation risk. • Non-invasive. • Inexpensive • Painless. • Don't require contrast material • Sedation is not required. SOLID NODULE VS CYST SOLID NODULE • Well defined • Ovoid shape • With uniform internal echoes CYST • Well defined • Round or oval shape • Anechoic • Enhance through transmission Limitations of the UTZ • Large body habitus, obese patients limit image quaility as the overlying adipose tissue. • Have trouble penetrating bone

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Performs very poorly when there is a gas It is operator-dependent. There is no scout image as there is with CT and MR. Once an image is acquired there is no exact way to tell which part of the body was imaged.

III. MAMMOGRAPHY • plays a central role in early detection of breast cancer because it can show cancer signs in the breast even years before a patient or physician would be able feel a breast cancer lump. • Screening mammography can assist in the detection of disease even if a woman has no complaints or symptoms BENEFITS • Use for early detection of breast cancers • Ability to detect small tumors / non-palpable nodules and microcalcifications, first indication of breast cancer LIMITATIONS • the appearance of an image may be compromised if there is powder on the breasts or undergone breast surgery. • need to compare the image to views from previous examinations • declines significantly with increasing breast density with dense breasts. • Breast implants can also impede accurate mammogram readings

IV. CT Scan • technique that uses X-rays to take many multiple "crosssection" images of the body, which are then assembled into a three-dimensional image by a computer. It is painless non -invasive radiological investigation. Uses of CT Scan • Detection, measurement, localization, extent of lesions and its relationship to other organs • Characterization of borders, composition and content • Used for staging tumor • Locating internal bleeding and organ damage in trauma patients • Detecting and staging tumors of various body parts • Detecting sources of infection and deep abscesses. • Detecting urinary stone disease without x-ray dye • Performing non-invasive blood vessel imaging (CT angiography DISADVANTAGES • Requires placement of an intravenous line for IV contrast. • Exposes patient to radiation. • Contrast toxicity or allergy • Most young children require sedation to undergo a CAT scan. Attenuation value Hyperdense • + 1000 calcium ------• >250 compact bone • 30-230 spongy bone • 70-90 bld coagulated • 50-60 whole bld

3 • Isodense • 20-70 • > 18 • < 18 Hypodense • 0 • -50 to -75 • -1000

soft tissue ExudateTransudate Water Fat Air

V. MRI - technique that uses a magnetic field and radio waves to take multiple 'cross-section' images of the body, which are then assembled into a threedimensional image by a computer • Uses radiofrequency waves • no ionization radiation is used • gives multiplanar display ( axial, coronal, sagittal and transverse) What are advantages of MRI Scan over CT Scan • No radiation. • No bony or air artifact. • Multi-section imaging. • High intrinsic contrast. • Specificity & extension of disease is more accurate. • Few diseases can diagnosis early. Limitations • Can not be used by people with pacemakers or other metallic implants. • More expensive than the price for CT. • Not very useful for bones

Even very slight movement of the part being scanned can cause very distorted images that will have to be repeated.