Diagnostic Imaging

Transcription

1 Diagnostic Imaging Diagnostic Imaging is no longer limited to radiography. Major technological advancements have lead to the use of new and improved imaging technologies. The following modalities will be discussed: Radiography Computed Tomography (CT) Magnetic Resonance (MR) Diagnostic Medical Sonography (US)

2 Radiography What is it? Radiography utilizes x-rays to produce an image How does it work? A vacuum tube boils off electrons which interact with a metal target and produce x-rays. The x-rays penetrate tissue based on its composition and provide a shadow gram.

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4 What does a radiograph look like? Radiographs are a gray scale representation of the tissue imaged. What are a few common exams and why are they performed? Chest radiographs- evaluation of lung and heart tissue. Musculoskeletal- evaluation of bones and joints. Abdomen radiographs- evaluation of organs. Contrast Studies of organ systems, GI or GU

5 Chest Radiography Emphysema CHF Metasteses

6 Musculoskeletal Scapular Fracture Dislocation C3-4 Severe Arthritis

7 Abdominal Radiography Gallstones Intestinal Obstruction

8 Abdominal Radiography contrast studies IVP UGI Ba Enema

9 Computed Tomography Computed tomography produces images through the use of an x-ray tube and a detector bank that receives and transmits the exit radiation from a patient to a computer for image construction

10 Single Slice Spiral CT Diagrams courtesy of CTISUS.com

11 Diagrams courtesy of CTISUS.com Multi-slice CT

12 First CT scanner from EMI 1973 Image constructed on a 80 X 80 matrix Current Image quality Image constructed on a 1024 X 1024 matrix

13 All CT images are acquired as axial images. Similar to a loaf of bread. These images can be restacked and sliced from front to back, coronals, or from left to right, sagittals. Below are two images of the same midbrain. The image on the right was done without the use of IV contrast, the image on the left used IV contrast and highlights the abnormal area. IV contrast is used to demonstrate highly vascular tissue.

14 This image shows a Shaded Surface Display or SSD image. The slices of axial information were restacked to create a virtual 3D model of the skull.

15 The images below demonstrate a large Abdominal Aortic Aneurism or AAA. The upper right image demonstrates the vessel at the very white area and the outer layers of the vessel as the light gray ring. Axial image Coronal image Volume image Maximum Intensity projection

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17 Splenic laceration I+ Renal Infarct due to arterial Injury I+ Orbital Fracture Images courtesy of CTISUS.com Gunshot wound with multiple fractures

18 Aortic dissection Axial image Pulmonary Embolism I+ MIP image Images courtesy of CTISUS.com

19 CT Angiography

20 Magnetic Resonance Imaging Patient inside a superconducting 1.5-tesla magnet. Some patients cannot be scanned because of claustrophobia. Courtesy General Electric Medical Systems, Milwaukee, Wis)

21 A proton with magnetic properties can be compared to a tiny bar magnet. The curved arrow indicates that a proton spins on its own axis. In the absence of a strong magnetic field, the protons (arrows) point in random directions and cannot be used for imaging. Fig & 36-2 Merrill s

22 Magnetic Resonance Imaging uses extremely strong magnetic field to flip protons using their magnetic properties. Scanners are described in Tesla or magnetic strength. Currently scanners are available from Tesla. For comparison the earths magnetic field is Tesla. Radio frequencies are used in MR imaging to create the image via the resonance of the sound wave off the anatomical tissue (proton).

23 This image shows remarkable anatomic detail in a midsagittal image of the head. Normal folds (F) on the inner surface of the brain are identified. CC, Corpus callosum; CL, cerebellum; B, brainstem; V, ventricle; A, air in sinuses. Fig Merrill s

24 Data from an entire volume within the imaging coil are obtained concurrently. The data may then be reconstructed into thin slices in any plane, such as the sagittal knee image shown here. This imaging sequence shows hyaline cartilage (arrowheads) as a fairly high signal intensity rim overlying the bone. Meniscal fibrocartilage (arrows) has low signal intensity. High signal intensity from joint fluid in a tear (curved arrow) within the posterior meniscus is visualized.

25 Coronal images through a normal brain. The T1- weighted image shows relatively low differentiation of gray matter (G) and white matter (W) within the brain. The heavily T2-weighted image shows improved differentiation between gray and white matter. CSF around the brain (arrows) and within the ventricles (V) also changes in appearance with changes in image type Fig , & Fig Merrill s

26 Image obtained after IV administration of gadolinium contrast material. Previously seen metastases are more conspicuous, and additional metastases are visualized. This coronal pelvis shows the prostate (P), which is enlarged and bladder (B). Hips (H) and acetabula (A) are also shown. A loop of the sigmoid (S) colon is on top of the bladder. Fig & 36-8

27 Chest images in a patient with extensive mesothelioma. The ascending and descending aorta (A) and pulmonary artery (P) are well visualized. Extensive rind of tumor (T) is visualized. This sagittal image demonstrate a thin line of diaphragm and fluid (arrows) between the liver (L) and tumor (T), indicating that the tumor has not invaded through the diaphragm. Fig Merrill s

28 Contrast-enhanced MRA of the abdominal aorta (arrow), showing the renal arteries (arrowheads) and iliac bifurcations (broken arrows). Contrast-enhanced MRA showing the carotid arteries (arrows) from the aortic arch (arrowhead) to the circle of Willis (broken arrow). Fig &27 Merrill s

29 Diagnostic Medical Sonography Ultrasound uses transducers or probes that create and receive sound waves. The sound waves penetrate tissue and are returned to the transducer. Similar to dropping a stone in a pond- the waves ripple out, until they interact with an object and return to the original area. Depending on the tissue type, the wave that returns will look different and be represented in an image.

30 Sagittal sonogram of the right upper quadrant over the medial segment of the left lobe of the liver (L),( the hepatic vein (hv),, and the inferior vena cava (IVC( IVC). Fig A,Merrill s

31 Transverse scan hepatic vein as it empties into the inferior vena cava with blood flow. Fig B,Merrill s

32 Echoes within the prominent portal vein (PV) represent thrombus (arrows) secondary to portal hypertension. Multiple hyperechoic and "bulls-eye" tumors (t) within the liver represent metastatic disease. Fig E Merrill s Fig B,Merrill s

33 Four chamber heart in a 31 week fetus. Spine (S) L Left ventricle (lv) Right ventricle (rv) Interventricular septum (s) separates ventricles. Left atrium (la) Right atrium (ra) Mitral valve (m) is on the left Tricuspid valve (t) is on the right. (l, lungs.) Fig Merrill s

34 Posterior coronal image of an 8-day8 day-old premature infant with a bilateral grade III bleed. The ventricles are slightly dilated, and a subependymal bleed (arrow) extends into the ventricular cavity Fig Merrill s