NUCLEAR RADIOLOGY

1. NUCLEAR RADIOLOGY CHAPTER22

2. RADIONUCLIDES • RADIONUCLIDE = RADIOISOTOPE • ISOTOPES- chemical elements with the same atomic number (# of protons) but different mass (# of neutrons). Because of this difference in mass, the nuclei of isotopes are unstable and they spontaneously decay, emitting radiation in the process. • See http://en.wikipedia.org/wiki/Isotope

3. RADIONUCLIDES • Some occur naturally, others are produced by bombarding the nucleus with subatomic fragments in a cyclotron to make them unstable. • Radionuclides can be used both for therapeutic and diagnostic purposes (I131). • Here we will look only at their diagnostic uses.

4. RADIATION HAZARD • “SLIGHT” – low dose, brief duration. • However, cells that are dividing rapidly are more susceptible to effects of radiation. • As such, radionuclides are not used in pregnancy or childhood if other diagnostic measures suffice. • Pregnant women should void frequently post-exposure to minimize exposure to the fetus. • In breast-feeding women, breast milk should be discarded post-exposure until radionuclide is eliminated.

5. RADIONUCLIDES USED IN DIAGNOSTIC TESTING • I131. • Technetium. (Tc-99m) • Gallium. • Indium. • Thallium. • Sodium chromate (Cr-51). • Cobalt (Co-57).

6. TECHNETIUM • Tc-99m- very unstable, has a short half-life of 6 hrs. Commonly used for numerous types of scans. • Can be combined w/ various biologically-active substances (“tagged”) that transport Tc-99m to target organs. • Bone Scans- Tc-99m combined with pyrophosphate. • Lung Scans- Tc-99m combined with albumin. • Other- RBC’s, thyroid, brain, hepatobiliary.

7. BONE SCANS • Tc-99m-labelled pyrophosphate incorporated into bone. • Entire body is scanned. • Detects areas of increased bone activity, osteolytic and osteoblastic. • Used to detect metastases, fractures. • Metastases show up on bone scan 6 months or so before they show on a plain radiograph.

8. Bone Scan – Metastatic Prostate Cancer

9. PLAIN FILM- 21 YOM W/ LEFT KNEE PAIN

10. BONE SCAN – OSTEOSARCOMANO METASTASES

11. BONE SCAN – PAGET’S DISEASE

12. BRAIN SCANS • 1) EVALUATION FOR DISRUPTION OF THE BLOOD-BRAIN BARRIER. • 2) PERFUSION SCAN.

13. BRAIN SCANS EVALUATION FOR DISRUPTION OF THE BLOOD-BRAIN BARRIER • Blood-brain barrier is a “complex system of membranes and fluid spaces that keeps substances in the blood from diffusing into the brain tissue.” Tc-99m given IV → localizes in areas where the blood-brain barrier is disrupted, by stroke, trauma, neoplasms, etc.

14. BRAIN SCANS PERFUSION SCAN • Lipid-soluble radiopharmaceuticals that can cross the blood-brain barrier used to evaluate perfusion of certain areas of the brain.

15. BRAIN SCAN (PET) - ALZHEIMERS

16. PET SCAN – ALZHEIMERS

17. GALLIUM SCAN • Gallium (Ga-67) localizes in areas of inflammation and in some neoplasms. • Used to detect areas of inflammation such as osteomyelitis, abscesses, and to look for occult metastases. • Highly sensitive and specific for detecting Hodgkin’s Disease, for staging and for post-treatment evaluation to assess response to therapy.

18. GALLIUM SCAN- LYMPHOMA

19. GALLIUM SCAN- 2 MOS POST-OP BUNIONECTOMY W/ CONTINUED PAIN OSTEOMYELITIS

20. INDIUM SCAN • INDIUM – In-111-labelled leukocytes go to areas of acute infection, not as much for chronic infection which is better evaluated by Gallium. • Indium is not taken up by neoplastic tissue. • Can also be used to tag RBC’s and paltelets. • Patients blood is drawn, tagged w/ Indium, and reinjected. Scan is done

21. GALL BLADDER SCAN • HIDA SCAN- used to evaluate for cholecystitis. • Tc-99m-labeled HIDA is excreted into the bile the same as bilirubin → fills the hepatobiliary tree. • In cholecystitis the gall bladder does not visualize. • Highly specific and highly sensitive.

22. HIDA SCAN- NON-VIS GALL BLADDER- ACUTE CHOLEYCYSTITIS

23. GASTROINTESTINAL SCANS • Variety of scans used to evaluate: • 1) GI Motility- gastric and esophageal emptying, reflux, etc. • 2) GI Bleeding. • 3) Presence of specific tissue types in abnormal locations- Ex Meckel’s Diverticulum – a congenital malformation of the terminal ileum in which a diverticulum is present and contains gastric or pancreatic tissue- associated w/ GI bleeding mostly in children- “currant jelly stools.”

24. MECKEL’S DIVERTICULUM

25. Tc-99-TAGGED RBC’SBLEEDING FROM JEJUNUM/J-TUBE

26. LIVER-SPLEEN SCANS • Tc-99m used to asses hepatic function and biliary function. • Tc-99m taken up by the reticuloendothelial system so can be used to image both the liver and the spleen. • Used to look for: changes of cirrhosis, areas of hypo- or hyperfunction, presence of metastases or an abscess, and to assess liver damage in trauma → leakage of bile into the abdomen around the liver.

27. NORMAL Tc-99 LIVER-SPLEEN SCAN

28. Tc-99 LIVER SCANFOCAL NODULAR HYPERPLASIA

29. 3 WEEKS POST-OP REPAIR OF LIVER LACERATION BILOMA

30. LUNG SCANS VENTILATION / PERFUSION SCANS • Done to R/O pulmonary embolus. • Ventilation scan- inhaled Xenon-123, exhaled. Scan looks for uniformity (or lack of) in the lungs, looking for areas that are not being ventilated, due to collapse, atelectasis, pneumothorax, etc • Perfusion scan- Tc-99m-labeled albumin injected, scan looks for uniformity (or lack of) in perfusion.

31. LUNG SCANS VENTILATION / PERFUSION SCANS • Comparison is done of the ventilation and the perfusion scans looking for a “mismatch” of perfusion in 2 or more lungs field. • Results are given as high, intermediate, or low probability, and used along w/ clinical suspicion to assess for likelihood of pulmonary embolus. • Need to compare to chest X-Ray to be sure symptoms are not due to other pathology.

32. V / Q SCAN – P.E. VENTILATION SCAN: NORMAL

33. V / Q SCAN – P.E. VENTILATION SCAN: NORMAL

34. V / Q SCAN – P.E. PERFUSION STUDY ABNORMAL: 2 AREAS OF “MISMATCH” (COMPARED TO VENTILATION)

35. ANGIOGRAM – P.E.

36. CARDIAC SCANS PERFUSION SCANS • Thallium is a physiologic analog of potassium. • Taken up by normally-perfused areas of myocardium. • Low uptake can indicate poor coronary perfusion vs. old infarction. • Often combined with a stress / treadmill test, aka “thallium treadmill.”

37. CARDIAC SCANS MUGA SCAN • Multiple gated acquisition scan. • Measures ventricular wall motion and ejection fraction. • Used in the evaluation of cardiac function in patients with cardiomyopathy, heart failure, ventricular aneurysms.

38. RENAL SCANS • Used to assess renal perfusion, structure, and/or excretory ability. When all 3 are measured, referred to as a triple renal study. • Tc-99m or iodine-tagged substance give IV, dynamic images taken to assess perfusion, static images taken to assess structure. • Can be used as an alternative to IVP if patients are allergic to iodinated-IVP dye.

39. THYROID SCANS I-123 • Used for evaluation of thyroid nodules. • I-123 given PO or IV. • “Cold” Nodules = do not take up the iodine. Associated w/ malignant nodules. • “Hot”Nodules = take up the iodine. • Associated w/ benign nodules. • Still need to prove benign or malnigant w/ biopsy.

40. THYROID SCANS I-131 • Used to detect metastases from thyroid malignancy. RAIU • Radioactive iodine uptake. • Uptake of iodine is a representation of its function. • Hypothyroidism – decreased uptake. • Hyperthyroidism – increased uptake.

41. THYROID SCAN – GRAVE’S DISEASE- I131 + Tc-99

42. Tc-99 THYROID SCAN- AUTONOMOUSLY FX NODULE

43. RBC TESTS RBC SURVIVAL TEST • Sodium chromate (Cr-51) binds w/ hemoglobin. • RBC’s can be tagged to evaluate RBC survival, to assess for hemolysis. RED CELL VOLUME • Cr-51 tagged onto RBC’s, other isotopes used to tag plasma. • Used in the evaluation of polycythemia vera.

44. SCHILLING TEST • Used to evaluate intestinal absorption of Vitamin B-12 in patients w/ macrocytic anemia. • B-12 tagged with Co-57. • Test measures how much Co-57 is eliminated in the urine. • Given with and without intrinsic factor to evaluate for pernicious anemia vs. malabsorption.

45. WHOLE BODY BONE SCAN SCAN – Tc-99m 54 YOF W/ BREAST CANCER, BONE SCAN TO R/O METASTASES

46. SAME PATIENT RENAL AGENESIS