Diagnostic nuclear medicine in diseases of the heart and circulatory system.

Transcription

1 Diagnostic nuclear medicine in diseases of the heart and circulatory system. Basic diagnostic methods: myocardial perfusion imaging radionuclide angiocardiography gated blood pool imaging radionuclide angiocardiography the first pass imaging perfusion scintigraphy of leg muscles Others: nuclear imaging of myocardial necrosis nuclear imaging of sympathetic innervation of the myocardium nuclear imaging of blood flow and metabolism of glucose or fatty acids in myocardium thromboscintigraphy lymphoscintigraphy of lower extremities

2 Myocardial heart perfusion imaging Radiopharmaceutical Radio thallium 201Tl chloride mechanism of the uptake by myocytes (proportional to the perfusion rate) active transport via cellular membranes the transport system by the sodium-potassium ATPase Complex of radiotechnetium (99mTc) passive diffusion via cellular and with metoxyisobuthyl (99mTc-MIBI) mitochondrial membranes accumulation proportional to electrical membrane potential Complex of radiotechnetium with phosphine ((99mTc-tetrophosmin) passive diffusion via cellular membrane dependant upon its electrical potential

3 Myocardial perfusion imaging Clinical applications: 1. Detection of coronary disease. 2. Evaluation of therapeutic effects of the acute infarct therapy. 3. Assessment of perfusion defects after the previous infarct. 4. Prognosing in the coronary disease. 5. Evaluation of the effectiveness of intravascular angioplasty or surgical revascularization. 6. Evaluation of viability of myocardium. 7. Assessment of the effect of coronary artery stenosis on myocardial perfusion.

4 Scintigraphic visualization of blood perfusion defects of the left ventricular myocardium - principle rest stress Perfusion of the myocardium Rest Stress Narrowing of a coronary artery reduces blood flow. Although blood supply at rest conditions is sufficient, it becomes to low during stress. This is why a critical narrowing of a coronary artery can be detected only when a radiopharmaceutical is administered to a patient during stress.

5 Myocardial perfusion; assessment by tomographic (SPECT) scintigraphy Transversal cuts Sagittal cuts Coronal cuts

6 A polar map presenting myocardial perfusion in a form of a 2D map, with apex in _ parts in the outer circle. the middle and basal A S L I A anterior wall, S septal wall, L lateral wall, I inferior wall LAD,LCX and RCA - regions of interest tentatively corresponding to the perfusion territories of 3 main coronary arteries.

7 Gated acquisition of myocardial perfusion scintigrams ECG Gating Gamma Acquisition module camera module Every R-wave releases a signal in a gating module informing a computer that a maximal diastole has just occurred. 1 1 Diastole 8 Systole 8 16 Every cardiac cycle is divided into 16 time bins. 16 Diastole

8 Gated SPECT simultaneous study of myocardial perfusion and contractility Regional EF Regional EF Thickening Thickening Perfusion Perfusion

9 Myocardial perfusion scintigraphy its position in diagnosis of coronary disease Clinical symptoms stress ECG age, sex risk factors Intermediate probability Low probability Myocardial perfusion scintigraphy Stress echocardiography Angio-CT High probability + Follow-up Low probability High probability Coronary angiography

10 Stress-induced ischaemia of left ventricular myocardium S R S R Sensitivity: 90-95%, Specificity: >75%

11 Post infarct scar in the left ventricle anterior wall S R S R

12 Post infarct scar and ischaemia of the postero-lateral wall of LV S R S R

13 SPECT (tomographic) myocardial perfusion study A Stress S L I Polar map A S L B Rest Before revascularisation Stress Rest After revascularisation

14 Hibernated myocardium scintigraphic criteria of viability (perfusion scintigraphy SPECT; metabolic scintigraphy PET) Glucose metabolism present (the most accurate radionuclide method for detection of viable myocardium!!!) 99mTc-MIBI 18FDG SPECT PET

15 Radionuclide angiocardiography gated blood pool imaging. A study of global and regional contractility of the left ventricle Radiopharmaceutical: 99mTc labeled erythrocytes (labeling in vivo) in circulation. Clinical applications: 1. Diagnostics of coronary disease. 2. Diagnosis of the cardiac aneurysm. 3. Monitoring of the functional state of the left ventricle. 4. Precise assessment of left ventricular function before a surgical intervention.

16 Gated Blood Pool Study Acquisition Gating ECG Detector

17 Gated blood pool study Radionuclide angiocardiography (proj. LAO 40) PT LA RA LV RV A PT RA RV LA LV - aorta - pulmonary trunk - right atrium - right ventricle - left atrium - left ventricle

18 Angiocardiography Gated Blood Pool Study Ed - Es EF= Ed x 100 % A scintigram with LV contours: diastolic (Ed) and systolic (Es) EF - ejection fraction of LV Ed - diastolic no of counts Es - systolic no of counts Ed Es counts proportional to ejection volume LV activity vs. time curve; changes of activity in blood inside the LV during representative cardiac cycle

19 Parametric images of ejection fraction and corresponding phases of LV evolution Scintigraphic image analyzed on a pixelby-pixel basis Right ventricle Left ventricle Gamma camera image LV in diastole Changes of activity between diastole and systole in particular pixels LV in systole EF=65% EF=26% EF=0% EF=21% Normokinesis Hypokinesis Akinesis Dyskinesis Phase of contraction delayed

20 Parametric images of ejection fraction akinesis Normal LV contour Abnormal in a patient with a history of an infarction of left ventricular inferior wall and septum

21 Parametric images and histograms of LV systolic phases Both ventricles contracting simultaneously (the same phase of contraction) Normal Parametric image of systolic phase Parametric image Histogram of LV systolic phase Histogram of systolic phase Contraction of inferior wall of the LV delayed Pathological A part representing delay in LV systolic phase Delay in LV systolic phase dyskinesis caused by the LV aneurysm A very sensitive method for detection of asynchronic left ventricular contracion

22 Radionuclide angiocardiography - first pass nuclear imaging A dynamic study. A bolus of activity travels through a central circulation Radiopharmaceuticals: 99mTc-pertechnetate, 99mTc-ethylenedicysteine (EC). Clinical applications: 1. Diagnostics of pathological shunts. 2. Assessment of heart ventricles contractility.

23 Heart and circulatory system Radionuclide angiocardiography first pass technique - Diagnostics of pathological shunts RV phase Pulmonary phase LV phase Normal passage of RPh through the central circulation QP/QS = 2,3 Left to right heart shunt

24 Radionuclide angiocardiography first pass technique RV phase Pulmonary phase LV phase 1. Vena cava sup. 2. Right atrium 3. Right ventricle 4. Lungs 5. Left ventricle 6. Aorta

25 Radionuclide angiocardiography first pass technique counts Real curve Fitted curves (A1, A2) time

26 Perfusion scintigraphy of leg muscles Radiopharmaceuticals: 201TlCl 99mTc-MIBI Clinical applications: 1. Diagnosis of lower extremities ischemia. 2. Assessment of the effectiveness of surgical therapy applied to obturatory atherosclerosis (lower extremities).

27 Blood perfusion of lower extremities muscular system (posterior view) femora L R calves Before treatment After treatment

28 Blood perfusion of lower extremities muscular system (posterior view) femora L R calves Before surgical treatment After the surgery