SP8:Cardiovascular System Scintigraphy Flashcards
What portion of an ECG wave represents the depolarization of the ventricles?
(a)QRS complex
(b) P wave
(c) ST segment
(d) T wave
(a) The QRS complex represents depolarization of the ventricles. The P-wave represents depolarization of the atria. The ST segment is representative of a pause between depolarization and repolarization of the ventricles. The T-wave represents repolarization of the ventricles.
A patient is only able to tolerate three images during a 201Tl chloride myocardial perfusion study. From those views listed, which would be the best choice of images to obtain?s
(a)RAO 10°, LAO 45°, and left lateral
(b) Anterior, LAO 25°, and LAO 60°
(c) Anterior, LAO 45°, and LAO 70°
(d) Anterior, LAO 70°, and left lateral
(c) In general, the 45° LAO should allow visualization of the septum and the inferoapical and posterolateral sections of the left ventricular wall. The anterior would then show the inferior, apical, and the anterolateral wall sections, and the 70° LAO would allow evaluation of the anterior, apical, inferior, and posterolateral all sections. If the septum is not well resolved on the 45° LAO due to the patient’s anatomy, another angle could be chosen, and the remaining two angles calculated by subtracting 45° for the “anterior” and by adding 25° for the steep lateral oblique.
Within what time frame must imaging be initiated following injection of 201Tl chloride in an exercise perfusion study?
(a)Within 5 min
(b) Within 10–15 min
(c) Within 20–30 min
(d) Within 4 h
(b) Following injection the patient ideally continues to exercise for 30 s to 1 min to allow localization of the radiopharmaceutical in the myocardium, and imaging begins as soon as possible. Most sources state 10-15 min as the maximum time allowed before imaging is begun. Although 5 min would be better, it is not usually possible to remove the patient from the exercise situation and into imaging position within this time.
Of the choices offered, which is the best imaging view for calculating right ventricular ejection fraction, using a first-pass study?
(a)RAO 60°
(b) RAO 30°
(c) Anterior
(d) LAO 10°
(b) First-pass studies are used to calculate the ejection fraction of the right ventricle and are generally performed using the 30 RAO position.
Of the choices offered, which is the best imaging view for calculating left ejection fraction?
(a)Anterior
(b) LAO 5
(c) LAO 45
(d) Left lateral
(c) The 45 LAO is, from the choices listed, the best choice for imaging when calculation of the left ventricular ejection fraction.
Given the data below, calculate the left ventricular ejection fraction.
Net ED = 58,219
Net Es = 35,317
(a)16%
(b) 39%
(c) 43%
(d) 60%
(b) Ejection fraction is the portion of blood in the ventricle that is pumped out with a single heartbeat. Ejection fraction is calculated as a percentage of the counts at end diastole using the formula:
(End diastolic counts - end systolic counts x 100) / (End diastolic counts - background counts)
Because the counts given in the question are net counts, we do not need to subtract background. Using the formula given, 39% is the ejection fraction.
The left ventricular ejection fraction determined is within the normal range.
Net ED = 58,219
Net Es = 35,317
(a)True
(b)False
(b) Ejection fraction of the left ventricle is usually considered normal if above 50%, though some sources state 55%. Normal EF for the right ventricle is >40%
Figure 1 shows computer-generated time activity curves over a cardiac cycle for two patients. Which curve represents the patient with the higher ejection fraction?
a: ED = 15319 - ES = 7886
b: ED = 24614 - ES = 8148
(a) 1a
(b) 1b
(b) Without calculating, it can be seen that there is a greater difference in counts at the end of end diastole vs. end systole (counts at end systole are nearly a third of those at end diastole) in the lower curve than on the upper curve (where end systolic counts are roughly half of end diastolic counts). The ejection fraction calculated for the upper curve is 66%. and the ejection fraction represented by the lower curve is 48%.
Which of the following cannot be evaluated by radionuclide ventriculography?
(a)Wall motion
(b) Wall thickness
(c) Aneurysmal flow
(d) Conduction abnormalities
(b) The radionuclide ventriculography can be used to assess wall motion but is not ideal for measuring wall thickness because camera resolution and partial volume effects limit the reliability of such measurements. Dyskinetic segments resulting from left ventricular aneurysms can be assessed by creating a paradox image (subtraction of the diastolic frame from the systolic frame) which may show increased activity in this case. Ventricular aneurysm may also cause parts of the wall to contract out of phase with the rest of the ventricle.
The images in Fig. 2 represent what type of images?
(Cardiac image > )
(a)Short axis
(b) Vertical long axis
(c) Horizontal long axis
(d) None of the above
(b) The vertical long-axis projections have been created during a SPECT 201Tl study. These images logically show the left ventricle from the septum to the lateral wall of the ventricle.
During a gated study, 24 images per cardiac cycle are obtained. If the patient’s heart rate is 65 bpm, the length of time per image is:
(a)3.8 ms
(b) 38 ms
(c) 4.1 ms
(d) 41 ms
(b) If there are 65 bpm, each cardiac cycle lasts 0.92 s (60/65=0.92). If that cycle is divided into 23 images, each images represents 38 msec (0.92/24 = 0.0384).
A right anterior oblique is useful for:
(a)Facilitating calculation of LVEF and RVEF on first pass
(b) Separating ventricles from the stomach on first pass
(c) Visualizing the lateral wall of the left ventricle
(d) Increasing patient comfort and potentially improving image quality
(a) First-pass studies are often performed using an RAO of 10-30 in order to allow calculation of ejection fraction for both right and left ventricles. This position also separates ventricular from atrial activity.
What will reverse the effects of dipyridamole?
(a)Dobutamine
(b) Cholecystokinin
(c) Aminophylline
(d) Adenosine
(e) Thallium
(c) Dipyridamole, adenosine, and dobutamine can be used to produce pharmacologic stress. The side effects of dipyridamole can be reversed by using aminophylline, which should be on hand during, and for 1 h following, dipyridamole administration. Side effects of dipyridamole include angina, dizziness, and headaches and nausea.
Which of the following will most negatively affect radionuclide ventriculography?
(a)Sinus tachycardia
(b) Sinus bradycardia
(c) Long Q-T interval
(d) Occasional PVC
(e) Sinus arrhythmia
(e) The R-wave signals the start of data collection, but each R-R interval is divided into segments, so if the R-R interval varies, as it does in arrhythmia, the data will be degraded. If this data is filtered out, the exam time will be increased.
The vertical long-axis view of the heart is most comparable to a:
(a)Coronal image
(b) Sagittal image
(c) Transverse image
(b) Vertical long-axis slices show sections of the left ventricle from the septum to the free wall and are most similar to sagittal images.
As an alternative to exercise studies, pharmacologic stress can be achieved through the use of any of the following except:
(a)Dipyridamole
(b) Aminophylline
(c) Dobutamine
(d) Adenosine
(b) Aminophylline may be used to reverse the side effects of dipyridamole which is used to create pharmacologic stress, as are adenosine and dobutamine.
In multigated analysis of the left ventricle, end systole is best described as:
(a)The frame with the highest number of counts in the ROI around the left ventricle
(b) The frame with the lowest number of counts in the ROI around the right ventricle
(c) The frame with the lowest number of counts in the ROI around the left ventricle, plus the counts from the background ROI
(d) All of the above
(e) None of the above
(e) End systole is represented by the frame with the lowest number of counts in the ROI around left ventricle.
All of the following will negatively affect a non-gated myocardial study with 201Tl chloride except:
(a)Wrong collimator
(b) Arrhythmia
(c) Incorrect COR
(d) Increased patient to detector distance
(e) None of the above
(b) The quality of a non-gated study would not be affected by arrhythmia, but using the wrong collimator, or center of rotation would, as would increased patient to detector distance.
Dipyridamole is supplied to a nuclear medicine department in 10-ml vials, each containing 50 mg. If a patient weighs 155 lb, how many milliliters must be injected for him to receive 0.56 mg/kg?
(a)7.9 ml
(b) 8.7 ml
(c) 17.4 ml
(d) 39.5 ml
(a) The patient’s weight must first be converted from pounds to kilograms (155 lb divided by 2.2 lb/kg = 70.7) and then multiplied by 0.56 mg to find the required dose (39.5 mg required). Since each ml of dipyridamole contains 5 mg, 39.5 is divided by 5 to find the number of ml to inject 39.5/5 = 7.9).
Which of the following does not describe correct preparation for an exercise myocardial perfusion study?
(a)NPO at least 4 h prior to radiopharmaceutical administration
(b) Catheter placement for injection of radiopharmaceutical during exercise
(c) Halt all medication 24 h before study
(d) None of the above
(c) Patients should be on NPO for at least 4 h before the exam, although some departments now allow water to drink, and in the case of diabetics, a light meal is often allowed. Caffeinated food and beverages are also often restricted after midnight before the exam, and sometimes for 24 h before it. Medications may or may not be taken before the exam according to the needs of the patient. Intravenous access is always in place before exercise begins to facilitate the administration of the radiopharmaceutical.
During an exercise gated study, the ECG pattern suddenly becomes dramatically different, although the patient is responsive, has an unchanged pulse rate, continues to exercise, and has no pain. The technologist should first:
(a)Start CPR
(b) Call a code
(c) Check for a disconnected lead
(d) Call the referring physician
(e) Do nothing
(c) In the situation described, the most likely explanation is a disconnected ECG lead and can quickly be confirmed. If this is not the case, medical assistance should be immediately sought.
Which of the following radiopharmaceuticals is not used to study the heart?
(a)99mTc sestamibi
(b) 99mTc HSA
(c) 99mTc PYP
(d) 32P chromic phosphate
(e) both (b) and (d)
(d) 99mTc sestamibi is used for myocardial perfusion imaging, 99mTc pyrophosphate has been used for myocardial infarct detection, and 99mTc HSA can be used for cardiac blood pool scintigraphy. 32P is a beta emitter and has therapeutic applications.
Which of the following is not a critical factor in obtaining a gated first-pass study?
(a)Tracer bolus of small volume
(b) Regular heartbeat
(c) The use of a multi-crystal gamma camera
(d) Positioning the heart in the center of the field of view
(e) Injection of at least 10 mCi of radiotracer
(c) The radioactive dose should be administered in as small a volume as possible, in the hope that the bolus will be intact upon entering the heart. Because the first-pass study represents very few heartbeats, it is important that those beats not be rejected. As with all dynamic studies, careful positioning is critical. Hot markers can be used to ascertain that the sternal notch and teh xiphoid process are within the FOV, and the detector head should be in an RAO position. A multi-crystal camera is ideal because of the high count rate, but is not strictly necessary. A high-sensitivity collimator is also preferred.
The best collimator for use during a first-pass study is:
(a)LEAP
(b) High sensitivity
(c) High resolution
(d) Medium energy
(b) A high-sensitivity collimator is also preferred.
A neonatal first-pass study is performed, and the time activity curve for the ROI around the left ventricle shows a peak of activity occurring before the activity peak on the lung ROI. This most likely indicates:
(a)Improperly drawn regions of interest
(b) Interventricular shunt
(c) Prolapsed mitral valve
(d) Radiotracer contained in a too high volume
(b) If activity is seen in the left ventricle before the lungs are visible, it is very likely that activity has passed from the right to the left side of the heart through an intracardiac shunt.
A nuclear medicine physician prefers that static myocardial perfusion images be obtained according to the best septal visualization. If the septum is well visualized on LAO 40, what other views should be obtained?
(a)Anterior, LAO 70
(b) RAO 20, LAO 60
(c) Anterior, LAO 60
(d) RAO 5, LAO 65
(d) In general, the 45° LAO should allow visualization of the septum and the inferoapical and posterolateral sections of the left ventricular wall. The anterior would then show the inferior, apical, and the anterolateral wall sections, and the 70° LAO would allow evaluation of the anterior, apical, inferior, and posterolateral all sections. If the septum is not well resolved on the 45° LAO due to the patient’s anatomy, another angle could be chosen, and the remaining two angles calculated by subtracting 45° for the “anterior” and by adding 25° for the steep lateral oblique.
Cardiac contraction is initiated in the:
(a)SA node
(b) AV node
(c) Bundle of His
(d) P wave
(a) The action potential that causes contraction arises in the sinoatrial (SA) node which is located in the right atria. It then travels to the AV node and through the bundle of His. The bundle of His branches into the right and left bundle branches which end in the Purkinje fibers; these innervate the individual contractile myocardial cells. The P-wave is that part of the ECG that represents the depolarization of the atria.
Treadmill exercise tests increase heart rate by:
(a)Increasing the slope of the treadmill
(b) Increasing treadmill speed
(c) Simulating infarct
(d) All of the above
(e) (a) and (b) only
(e) A commonly used exercise protocol is the Bruce protocol which gradually increases both the speed and the grade of the treadmill. A false-negative exercise myocardial perfusion study may be the result of insufficient exercise.
A high-resolution collimator would be most appropriate for:
(a)Myocardial perfusion study with 201Tl chloride
(b) Myocardial perfusion with 99mTc sestamibi
(c) First-pass study with 99mTc DTPA
(d) Myocardial imaging with 99mTc pyrophosphate
(b) The high photon flux involved with 99mTc sestamibi necessitates the use of a high-resolution collimator. It is sufficient to use a low-energy all-purpose collimator (LEAP) for the 201Tl exam (as well as the infarct study with pyrophosphate). High-sensitivity collimation is preferable to a first-pass study.
On Monday morning, a technologist receives a telephone request to perform a myocardial study with 99mTc PYP for detection of a myocardial infarct suspected to have taken place that morning at about 8:00 a.m. What should be done?
(a)The patient should be injected, but not scanned until at least 8:00 a.m. on Tuesday.
(b) The study should be delayed until 8:00 a.m. on Tuesday.
(c) The study should be delayed until 8:00 a.m. on Thursday.
(d) The patient should be injected and scanned as soon as possible.
(b) Pyrophosphate and other bone agents will bind in sites of myocardial injury because calcium will travel into the damaged cells, but this does not take place until at least 12 h and more often between 24 and 72 h after an infarct has occurred. The scan should not take place before 24 h after the suspected even.
Infarct-avid myocardial imaging with 99mTc PYP is usually interpreted by comparing cardiac activity with:
(a)Rib
(b) Sternum
(c) Kidneys
(d) All of the above
(e) (a) and (b) only
(e) Uptake in the myocardium is usually compared to the uptake in the ribs and sternum when interpreting infarct studies.
If a SPECT myocardial study with 99mTc PYP is performed using 64 views of 20 s each over 360, how long will the study take assuming continuous rotation?
(a)18 min
(b) 21 min
(c) 92 min
(d) 112 min
(b) The number of views is multiplied by seconds per view and divided by 60 to obtain the total number of minutes. If this was acquired in step-and-shoot mode, the stepping time would need to be added to find the total acquisition time. Myocardial perfusion SPECT studies are usually performed over 180.
