1 Introduction to Diagnostic Radiology ImagingBY Dr Riaz Mohammad

2 Definition of RadiologyRadiology is a medical specialty using medical imaging technologies to diagnose and treat patients.

3 Diagnostic imaging ModalitiesPlain x-rays Fluoroscopy(real time imaging, contrast often used) Mammography Ultrasound CT Scan MRI Angiography Nuclear Medicine,conventional,Spect/Pet and PET/CT fusion Which of these modalities use ionizing radiation?

4 X-Rays is a form of electromagnetic radiation:They are produced when high energetic electrons interact with matter. Kinetic energy of electron are converted in to electromagnetic energy by atomic interaction

5 Three things can happenX-rays can: Pass all the way through the body Be deflected or scattered Be absorbed Q: Where on this image have x-rays passed through the body to the greatest degree?

6 Schematic diagram of x-ray machine

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8 Continue X-ray image • The image is the result of interaction of X-ray beam and body tissue • X-rays that pass through a structure easily are least absorbed and therefore cause blackening on the radiograph (air-lung). • Whereas structure that absorbs or reflects x-ray most appear white. (bone-metallic). • Soft tissues lie in between are gray. According to thickness of these, the shades of gray differ. • Projections are usually described by the path of the x-ray beam. Thus, the term PA (poster anterior) view designates that the beam passes from the back to the front, the standard projection for a routine chest film. • The image on an x-ray film is two-dimensional. All the structures along the path of the beam are projected on to the same portion of the film (superimposed). Therefore, it is often necessary to take at least two views to gain information about the third dimension

9 Image key:5 Basic Radiographic DensitiesLingo Density Opacity Radiographic image key or Air Fat Soft tissue/fluid Mineral Metal 5 Observable Densities: 1 2. 4 3. Name these radiographic densities?

10 Ultrasound Is a very high frequency sound directed in to the body from a transducer placed in contact with the skin. In order to make a good acoustic contact, the skin is smeared with a gel like substance. As the sound travel through the body, it is reflected by the tissue interfaces, which is pick up by the same transducer and convert it to an electrical signal. Machine process the data and form a grey scale image. Not invasive, cheap and available in almost every hospital. No ionizing radiation Safe for pregnant patient Operator dependent There is organ limitation( It can not penetrate air or bone so we can not use with lung or brain for instance) Fluid is a good conductor of sound, therefore, ultrasound, is particularly good imaging modality for diagnosing cyst and other fluid filled structures like urinary bladder and biliary system and demonstrating the fetus in its amniotic sac.

11 Lingo Echogenicity /Hypo echoic or hyper echoic Shadowing Doppler for flow

12 Ultrasound

13 Ultrasound Ultrasound is often used to determine weather the structure is solid or cystic Cyst and other fluid filled structure produce a large echo from their but no echo from the fluid contained with in them. Also more echo than usual are received from behind the fluid filled structures, an effect called acoustic enhancement. Conversely with calcified structures, e.g. gall stone, there is great reduction in the sound that will pass through, so a band of reduced echoes, referred to as an acoustic shadow is seen behind the stones.

14 US Indications: OB/GYN.Evaluation of first, second and third trimester pregnancy Congenital Anomalies. Evaluation of placenta Previa and hemorrhages Evaluation of gynecological diseases. Abdominal indications. Muscuskeletal indications Neonatal brain ultrasound.

15 Ultrasound Advantages No ionizing radiation Safe for pregnant womenApplicable to any plane Cost-effective Portable Real-time imaging Disadvantages 1.Operator dependent 2. Can not penetrate every structure like bone and air containing organs

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17 2D vs 3D

18 3-4 D U/S images

19 Computed Tomography Computerized (or computed) tomography, and often formerly referred to as computerized axial tomography is an X-ray procedure that combines many X-ray images with the aid of a computer to generate cross-sectional views and, if needed, three-dimensional images of the internal organs and structures of the body. Computerized tomography is more commonly known by its abbreviated names, CT scan or CAT scan. A CT scan is used to define normal and abnormal structures in the body and/or assist in procedures by helping to accurately guide the placement of instruments or treatment planning. There is more sensitive x-ray detection system and the image consist of sections (slice) through the body and the data is manipulated by computer. CT has a very small difference in x-ray absorption value compared with conventional radiography, the range of densities recorded is increase approximately 10 fold. So gradation of densities with in the soft tissues can be recognized e.g brain substance from CSF and tumor from normal tissues. Even grey and white matter of brain can be differentiated. The major risk behind the CT is ,that 1 brain CT scan radiation is 200 X-ray and 1 pelvis CT is 400 x-ray which means do not request Ct scan unless it is needed and we can not do it for pregnant women unless it is necessary.

20 CT scan

21 Lingo: Attenuation Density Enhancement Hounsfield Units -1000 air ***-100 fat 0 water *** 20-80 soft tissues 100’s bone/Ca/contrast >1000’s metal Lingo: Attenuation Density Enhancement

22 Computed Tomography

23 MRI

24 MRI Lingo: Signal intensity(Hyper intense or hypo intense) T1 T2 FLAIR. (Fluid attenuated inversion recovery) Enhancement No radiation Strong magnetic field No pacemakers No electronic implants

25 MRI(magnetic resonance imaging)To perform the test, the patient is put in the MR scanner which form a strong magnetic field around the area to be imaged Hydrogen atom(protons) in water molecules and lipids are excited with radio waves by radiofrequency coil which after a while return to the equilibrium state produce radiofrequency signal. Radiofrequency coils are switched off and an to change the direction of magnetic field. When ever molecules spin around they produce a light radio waves. MRI machine detect this change and convert it to an MR image. MRI contrast agent. Gadolinium DTPA( Ethylene Triamine Penta acetic acid) is used as contrast agent. It is used with T1W images only. T1weighted. Fat appear white, fluid dark and sub acute hemorrhage also appear white T2 weighted. Fluid appear white, fat less white compared to T1 weighted Bone appear black on all sequences Air also appear black on all sequences.

26 MRI Disadvantages Advantages of MRIBetter contrast resolution and tissue discriminations Many detail without contrast There is no ionizing radiation Procedure of choice for MSK It can be done for pregnant women with caution. Many sequences to play with characteristic abnormal tissues Multiplanner so image can be taken in any plan with out changing the position of the patient. MR angiogram can be perform wit out introducing contrast media Expensive and time consuming Patient fear it and dislike it because it is a narrow place(claustrophobia) . Now a days open MRI system has over come this problem Since it is magnetic no metal can be allowed Patient has to keep still during the producer.

27 MRI continue Axial T2 Weighted T1 Weighted

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30 Contraindications of MRI if there isCardiac pace maker Intracranial vascular clips Neurostimulators of any kind Intraocular metallic foreign body Ossicular implants Any metallic implants, rods, metal plates and pins. Heart failure Surgical clips on arteries and wire sutures

31 Very important to know different planes

32 Fluoroscopy Utilizes X-Rays Real-time imagingUtilizes image intensifier May involves use of contrast agents

33 Fluoroscopy Mechanism: Continuous X-ray beam from below patient, amplified by intensifier above patient; shown on high-resolution television screen Provides real time moving image of internal structure

34 Fluoroscopy Advantages DisadvantagesWidely Available Inexpensive Functional and Anatomic No sedation required High radiation dose ingestion/injection of contrast Patient cooperation Time consuming

35 Barium swallow spot films

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37 Angiography 1. Conventional angiography 2. CT angiography 3Angiography 1.Conventional angiography 2.CT angiography 3.MR angiography Conventional or catheter angiography. Radiographic visualization of blood vessels after injection of radioopaque contrast media in to the blood vessels Contrast is rapidly injected in to the blood vessel and a series of images are taken rapidly to follow the flow of contrast in the blood vessel. It is performed under fluoroscopy. Angiography is indicated to diagnose vascular pathology. Conventional angiography is diagnostic as well as therapeutic.

38 Thoracic aorta

39 Abdominal aorta

40 Renal angiogram Cerebral angiogram

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43 Nuclear Medicine (Scintigraphy)Bone Scan

44 How nuclear medicine detects problems within different areas in our organIn order to investigate a body organ. A suitable radioactive tracer having a particular affinity for that organ is injected into the blood stream this is up taken by the organ of interest which is then assessed by imaging with the gamma camera. The image beside explains how whole process works.

45 SPECT: Single-photon emission computed tomography (SPECT) is a nuclear medicine tomographic imaging technique using gamma rays. It is very similar to conventional nuclear medicine planar imaging using a gamma camera However, it is able to provide true 3D information which is then presented as cross sectional image. PET Scanner: positron emission tomography A PET scan uses a small amount of radioactive material (tracer). The tracer is given through a vein (IV), most often on the inside of your elbow. The tracer travels through your blood and collects in organs and tissues. This helps the radiologist see certain areas of concern more clearly A PET scan measure the important body functions such as blood flow, oxygen use and glucose metabolism

46 PET/ CT fusion

47 PET SCAN

48 Mammography Mammography is the process of using low-energy X-rays (usually around 30 kVp) to image the human breast and is used as a diagnostic and a screening tool. The goal of mammography is the early detection of breast cancer, typically through detection of characteristic masses and/or microcalcifications.

50 Diagnostic Mammogram Diagnostic mammograms are used after suspicious results on a screening mammogram or after some signs of breast cancer alert the physician to check the tissue. Such signs may include: A lump, Breast pain and nipple discharge For woman presenting with clinical evidence of breast disease, palpable mass or other symptom Specific projections are used to Rule out cancer Demonstrate suspicious area seen on screening mammogram

52 Routine diagnostic mammography projections1.Craniocaudal (CC) 2.Medio lateral oblique (MLO)

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54 Additional views. Such as magnification views are done to detect microcalcifications

55 Fibro adenoma commonest benign tumor of breastBreast cancer

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57 Breast cyst on mammographyIt appear like a mass The lesion on ultrasound is simple cyst

58 Breast ultrasound is usually done to differentiate between solid and cystic masses

59 Dense breast MRI. Superior modality to Detect occult cancer Cancer dense breast Multi centric cancer Detection of cancer in breast with implants

60 Breast implants

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63 RUQ pain in a middle age patient.Identify these four imaging modalities used in this patient?

64 The End