Imaging in Surgery Final Year MBBS .pptx

Imaging in Surgery Final year MBBS

1. Imaging in Surgery

2. Introduction -Imaging is a veritable tool in surgical patients. -Radiological investigations remain vital to the diagnosis, preparation and follow up of patients .

3. Uses # To aid in diagnosis of a surgical disorder # To guide a surgical procedure # Monitoring # Interventional radiological techniques

4. Imaging Techniques X rays Fluoroscopy Ultrasound CT MRI Nuclear medicine

5. Radiography Oldest and commonest imaging technique Uses ionising radiations Parts : X ray tube , collimator, table , film Principle : X-rays emitted from an X-ray source are absorbed to varying degrees by different materials and tissues and therefore causes different degree of darkening of radiographic films , resulting in an image

6. Advantages cheap Available Short developing time Good for assessing bone

7. Disadvantages ionising radiation Poor soft tissue contrast

8. Fluroscopy uses X-rays like in conventional radiographs. However, a fluorescent screen,image intensifier and a video converter is used Allows for real time imaging Higher dose of radiation Extensive use in functional studies , interventional radiology and imagine guidance

9. Ultrasound Second most common method of imaging Relies on high frequency sound waves generated by a transducer containing piezoelectric material Principle : Generated sound waves are reflected by tissue interfaces and by ascertaining the direction and time taken for a pulse to return it is possible to form an image

10. CT scan Method of cross sectional imaging CT uses a computer to create an image from an integration of multiple X-rays exposures taken in a circle round the patient Heavy ionising radiation dose Parts : Gantry, X-ray source,detectors table

11. MRI Newest of the imaging techniques Does not use ionising radiation Parts : magnet , radio frequency coil , table Principle : Body tissues consist of protons and electrons. In a strong uniform magnetic field such as a MRI scanner , these nuclei align themselves with the main magnetic field.A brief radio frequency pulse is applied to alter the motion of nuclei. When removed , the nuclei realign with the main magnetic field,emitting energy.

12. T1- fat, methemoglobin, mucinous fluid appear white. Important for delineating anatomy T2- fat, water and most pathological fluid appear white. Highlights pathology better

13. Radionuclide scan A radioactive element (radionuclide) is administered as a radio pharmaceutical agent and a detector ( gamma camera ) is used to record and localise the emission ( gamma ray ) and thus form an image Agents : technetium,gallium,thallium,iodine These are usually labelled for organ specificity

14. PET scan An extension of radionuclide studies Same principle but uses substances that emit positron and not gamma rays Agent : 18F-2Fluoro-2deoxy-D glucose ( FDG)

15. Others CONTRAST STUDIES * positive , negative and combine * Radiocontrast * MRI contrast * USS contrast SPECT

16. Application in surgery Acute abdomen : Bowel obstruction, perforation , ischemia , GIT haemorrhage , inflammatory lesions. Modalities:- Chest X-ray , abdominal X-ray , USS , CT scan , MRI Trauma : USS , CT , MRI Masses : USS , Contrast studies , CT , MRI

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