310 likes | 681 Views
Radiology in GIT. Introduction. SLO. To know the types and principles of radiological investigations available for evaluation of GIT disorders. Indications for these investigations, advantages and disadvantages. What are the Radiological investigations for following clinical scenario?.
E N D
Radiology in GIT Introduction
SLO • To know the types andprinciples of radiological investigations available for evaluation of GIT disorders. • Indications for these investigations, advantages and disadvantages.
What are the Radiological investigations for following clinical scenario? • Acute abdominal pain and vomiting • Chronic, colicky abdominal pain with distension, vomiting, constipation
Conventional X rays • Roentgen- 1895 • X rays emitted from x ray source are absorbed to varying degrees by different tissues and structures causing different degrees of blackening of radiographic film • High density tissues cause reduced blackening. E.g., bone, minerals as compared to air. • Intraluminal contrast/ intravenous. • i
Plain X-rays- Upright, supine, lateral decubitus • Contrast X-rays- Barium swallow- pharynx, esophagus, G- E junction Barium meal- stomach and duodenum Barium meal follow through- duodenum, jejunum, ileum Small bowel enema(enteroclysis)- Barium enema- colorectal diseases Cholangiography- I.V./ on table/ post op
Advantages- cheap, easily available, easily reproducible, comparable • Disadvantages- radiation hazard with repeated/ contrast x rays, lack of soft tissue contrast
Interpretation of the images • Clinician/ Radiologist
Ultrasound examination • High frequency sound wave generated by transducer containing piezoelectric material. • 3 to 20 M Hz • Modifications – EndocavitaryUsglike transvaginal,transrectal, endoscopic Usg, Laparoscopic Usg, Doppler Usg • Cheap, safe • Expertise/ air, bone xx
C T Scan • Gantry containing X ray tube, filters and detectors revolve round the patient at different angles and projections • Images are digitally reconstructed to produce two dimensional grey scale image of slice of the body. Hounsefield units • Can be combined with intravenous/ oral or rectal contrast for better delineation of tissues.
Magnetic Resonance Imaging • The nuclei contain protons and electrons and they have a characteristic motion in a magnetic field • Brief radiofrequency pulse is applied to alter the motion of nuclei. Once the radiofrequency pulse is removed, the nuclei will realign themselves with magnetic field( relaxation). • This emits radiofrequency signal which is recorded, encoded and grey scale images are constructed. • Staging of Ca rectum, liver tumour assessment, study of biliary tract ( MRCP)
T1 • T1 weighted images- fat, mucous fluid appear bright. To see the normal anatomy • T2 weighted images- water and pathological process appear brighter • Can be combined with I V contrast Gadolinium
Hazards of radiological imaging • Ionizing radiation • Contrast media- allergic reaction, nephrotoxic
Conclusion • Choose simplest, cheapest, appropriate investigation • Invasive, expensive tests if the disease is complex • The hazards of radiological investigations should always kept in mind while referring for these tests.