First Pass in Nuclear Cardiology Presented by Jennifer S. Love, CNMT, NCT, PET

Objectives Examine the concept of First Pass and its role in Nuclear Cardiology imaging. Define and describe the necessary technical aspects of First Pass in order to obtain quality information. Evaluate radiopharmaceuticals that can be used to perform the procedure. Compare and contrast various methods of obtaining an ejection fraction and the advantages and disadvantages of each.

What is First Pass? “A dynamic series of images of a radiopharmaceutical bolus as it flows sequentially from the vena cava into the right atrium, right ventricle, pulmonary arteries and lungs, left atrium, left ventricle, and aorta.” Nuclear Cardiology Technology Study Guide 2010 SNM, Inc., p.30.

Why do a First Pass? Evaluate for cardiotoxicity in patients undergoing chemotherapy treatment Reproducible RVEF and LVEF Evaluation of Left-to-Right Shunt (bump on pulmonary TAC) True STRESS EF (acquired during actual exercise) Comparison of Rest and Stress EF can help evaluate for Triple Vessel Disease

This is what we are after! Stress FP Rest FP

How does it work?

Crystal technology Single crystal = gamma camera Multi-crystal = First Pass Solid state detector = (CZT) the future of imaging technology?!

Single crystal NaI (Tl) Emit a flash of light proportional to the energy of the photon that is stopped by the crystal. PMT’s then convert the light into electrical pulses.

Multi-crystal Multiple crystals associated with an individual PMT on the detector assembly Principles and Practice of Nuclear Medicine, Paul J. Early and D. Bruce Sodee, 2nd edition, p.253.

Solid State Detector CZT = Cadmium Zinc Telluride Converts the incident photon directly into electrical pulses High sensitivity High resolution

PROCEDURE

How does it all happen? Verify patient identification using two identifiers (National Patient Safety Goal) Start an IV Position the patient Connect the dose “load the line” Start the acquisition Push, push, push!! (2-3 sec for good quality bolus)

IV Access Antecubital or external jugular preferred (according to ASNC guidelines) Right arm > left arm 18 to 22 gauge catheter Portacath, Hickman, PICC line (central lines)

Set-up Extension tubing Three-way stopcock 10 – 20ml saline flush Dose (10 – 30 mCi in 0.4 - 1.0 ml)

Patient Positioning Anterior or slightly RAO Upright or supine Shallow RAO helps eliminate anatomic overlap May want to use transmission source Upright or supine Pulmonary background is reduced in the upright orientation

Connect the dose Needs to be luer lock not a slip lock! Extension tubing 3-way stopcock 10-20ml saline flush Needs to be luer lock not a slip lock!

GO TIME!! “load the line” Press START Push, push, push!!! 2 – 3 sec for a good bolus

TRIVIA QUESTION!!!

What is the only Tc radiopharmaceutical that may NOT be used to perform a FIRST PASS?

Tc Radiopharmaceuticals 99mTc-DTPA 99mTc-Tetrofosmin 99mTc-Sestamibi 99mTc-MDP 99mTc-MAA 99mTc-MAG3 99mTc-Tagged RBC’s 99mTc-Pertechnetate

99mTc MAA (because it gets trapped in the lungs)! RV – LUNGS - LV All the other RP’s circulate all the way through the heart – MAA stops in the lungs!

99mTc-DTPA RP of choice is… because of its renal excretion, minimizing radiation exposure to the patient

Watch this!!!

Acquire the raw data Evaluate the bolus Evaluate the beat histogram Pulmonary Transit Time Right Ventricle Ejection Fraction Left Ventricle Ejection Fraction

Evaluating the Bolus

Beat Histogram ED = End Diastole ES = End Systole

Pulmonary Transit Time

Right Ventricle

Right Ventricle ED = End Diastole ES = End Systole

Left Ventricle

Left Ventricle ED = End Diastole ES = End Systole

First Pass at Stress

Comparison of Rest vs. Stress

Comparison of Rest vs. Stress

First Pass vs. MUGA First Pass MUGA Advantages Advantages Reproducibility Lower radiation exposure when compared to tagged RBC’s 30 sec acquisition Measurement of RVEF True stress EF Disadvantages Technical pitfalls Camera/computer need to be able to accept lots of counts in short time frame Advantages No specialty camera needed IV placement is not an issue Disadvantages Need to tag red blood cells Longer acquisition time Higher radiation exposure

Questions?