Comparison of Comparison of 8282Rb PET/CT Rb PET/CT Myocardial Perfusion Imaging with Myocardial Perfusion Imaging with

Cardiac CatheterizationCardiac Catheterization

byby

H. Backhaus, C. JohnsonH. Backhaus, C. Johnson

St. Joseph’s Hospital,St. Joseph’s Hospital,

Marshfield, WIMarshfield, WI

BackgroundBackground

– St. Joseph’s Hospital is a 500+ bed facility St. Joseph’s Hospital is a 500+ bed facility located in north central Wisconsin. located in north central Wisconsin.

– It serves the primarily rural population of It serves the primarily rural population of Northern and Central Wisconsin plus Upper Northern and Central Wisconsin plus Upper MichiganMichigan

– St. Joseph’s has one of the largest Nuclear St. Joseph’s has one of the largest Nuclear Medicine departments in the regionMedicine departments in the region

– It is also the only facility in the State of It is also the only facility in the State of Wisconsin to utilize Wisconsin to utilize 8282Rb PET/CT imagingRb PET/CT imaging

Myocardial Perfusion ImagingMyocardial Perfusion Imaging

The primary modality used for myocardial The primary modality used for myocardial perfusion studies at St. Joseph’s Hospital perfusion studies at St. Joseph’s Hospital is is 99m99mTc-sestamibi SPECT/CT imagingTc-sestamibi SPECT/CT imaging

However, for all patients weighing over However, for all patients weighing over 250 lbs or with a BMI 250 lbs or with a BMI ≥ 35 ≥ 35 8282Rb PET/CT Rb PET/CT imaging is preferred by our physiciansimaging is preferred by our physicians

Why?Why?

8282Rb emits a higher energy gamma than Rb emits a higher energy gamma than 99m99mTcTc

The higher energy gamma is more able to The higher energy gamma is more able to penetrate excess tissuepenetrate excess tissue

This results in more counts reaching the This results in more counts reaching the cameracamera

Ultimately, higher quality diagnostic Ultimately, higher quality diagnostic images are obtainedimages are obtained

Plus…Plus…

8282Rb PET/CT imaging takes only about 1 Rb PET/CT imaging takes only about 1 hour to complete (hour to complete (99m99mTc-sestamibi is a 2-Tc-sestamibi is a 2-day protocol for obese patients)day protocol for obese patients)This results in less time spent at the This results in less time spent at the hospital by the patients – making them hospital by the patients – making them much happiermuch happierAnd, this allows more patients to be seen And, this allows more patients to be seen in a shorter amount of time – resulting in in a shorter amount of time – resulting in higher throughputhigher throughput

ObjectivesObjectives

The purpose of this study was to The purpose of this study was to determine the diagnostic quality of determine the diagnostic quality of 8282Rb Rb PET/CT myocardial perfusion imaging on PET/CT myocardial perfusion imaging on obese patients obese patients This was done by comparing the Nuclear This was done by comparing the Nuclear Medicine physician’s interpretations of Medicine physician’s interpretations of these images to the results of cardiac these images to the results of cardiac catheterizations performed on the same catheterizations performed on the same patientspatients

MethodsMethods

Out of all patients seen Out of all patients seen between January 2008 & between January 2008 & March 2009 thirty-six March 2009 thirty-six (25 male, 11 female) (25 male, 11 female) underwent both underwent both 8282Rb Rb PET/CT MPI & cardiac PET/CT MPI & cardiac catheterization catheterization

All patients were imaged All patients were imaged on a Philips Gemini GXL on a Philips Gemini GXL PET/CT systemPET/CT system

Methods (cont.)Methods (cont.)

Surview Topogram Surview Topogram CT Transmission CT Transmission ScanScanInjected 30-50 mCi Injected 30-50 mCi 8282Rb over 30-60 secRb over 30-60 sec6 min of Gated Rest 6 min of Gated Rest ImagesImages

Adenosine Stress Adenosine Stress (over 7 min)(over 7 min)Injected 30-50 mCi Injected 30-50 mCi 8282Rb over 30-60 sec Rb over 30-60 sec (2 min after start of (2 min after start of adenosine injection) adenosine injection) 6 min of Gated Stress 6 min of Gated Stress ImagesImagesCT Transmission CT Transmission ScanScan

Methods (cont.)Methods (cont.)

Images were processed by technologist & read Images were processed by technologist & read by either a Nuclear Medicine physician or by either a Nuclear Medicine physician or Nuclear CardiologistNuclear CardiologistAll 36 patients in this study were referred to & All 36 patients in this study were referred to & received Cardiac Catheterization following their received Cardiac Catheterization following their 8282Rb PET/CT scansRb PET/CT scansPhysicians’ reports from the Nuclear Medicine Physicians’ reports from the Nuclear Medicine procedures were compared to the physicians’ procedures were compared to the physicians’ reports from the Catheterizations in order to reports from the Catheterizations in order to determine any correlation between the findingsdetermine any correlation between the findings

Results…

Out of the 36 patients studied...Out of the 36 patients studied...

26 Confirmed Stenoses

3 Confirmed

MI

2 Confirmed

Clear

1 Confirmed Non-stenotic

Abn.3 False +

1 False -

Example #1Example #1(attenuation corrected images)(attenuation corrected images)

- No definitive fixed defects - No definitive fixed defects - Moderate size, mild, stress-induced defect of mid lateral wall- Moderate size, mild, stress-induced defect of mid lateral wall

Example #2Example #2(attenuation corrected images)(attenuation corrected images)

- Confirmation of known fixed defect- Confirmation of known fixed defect- Prior MI to apex- Prior MI to apex

Example #3Example #3(attenuation corrected images)(attenuation corrected images)

- No ischemia- No ischemia

Example #4Example #4Attenuation corrected vs. non attenuation correctedAttenuation corrected vs. non attenuation corrected- Corrected images show more realistic perfusion- Corrected images show more realistic perfusion

- Uncorrected images show fixed defect in the inferior wall- Uncorrected images show fixed defect in the inferior wall

(attenuation corrected) (uncorrected)(attenuation corrected) (uncorrected)

Results (cont.)Results (cont.)

100% of the perfusion defects to locations in the 100% of the perfusion defects to locations in the myocardium supplied by the LCX artery (lateral myocardium supplied by the LCX artery (lateral wall) were verified by catheterizationwall) were verified by catheterization89% of the perfusion defects involving areas of 89% of the perfusion defects involving areas of the heart typically supplied by the LAD artery the heart typically supplied by the LAD artery (anterior wall & apex) were confirmed to be LAD (anterior wall & apex) were confirmed to be LAD occlusions by cardiac catheterizationocclusions by cardiac catheterization79% of the perfusion defects to areas of the 79% of the perfusion defects to areas of the heart supplied by the RCA (inferior wall) were heart supplied by the RCA (inferior wall) were confirmed by cardiac catheterizationconfirmed by cardiac catheterization

ConclusionsConclusions

Based on these results, it seems more difficult to make Based on these results, it seems more difficult to make an accurate diagnosis of a small perfusion defect to an an accurate diagnosis of a small perfusion defect to an area of the myocardium that is partially blocked by a area of the myocardium that is partially blocked by a solid organ such as the liver (count attenuation)solid organ such as the liver (count attenuation)Attenuation correction software does help improve the Attenuation correction software does help improve the ability to differentiate true perfusion defects from organ ability to differentiate true perfusion defects from organ attenuationattenuationHowever, smaller perfusion defects can sometimes be However, smaller perfusion defects can sometimes be maskedmaskedNevertheless, 89% of the perfusion defect diagnoses Nevertheless, 89% of the perfusion defect diagnoses made using the made using the 8282Rb PET/CT scans correlated Rb PET/CT scans correlated completely with the findings of cardiac catheterizationcompletely with the findings of cardiac catheterization

Conclusions (cont.)Conclusions (cont.)

8282Rb MPI can also be a valuable tool for Rb MPI can also be a valuable tool for detecting non-stenotic abnormalities that have a detecting non-stenotic abnormalities that have a deleterious effect on the blood flow to a patient’s deleterious effect on the blood flow to a patient’s heartheart

In one case an RCA that originated from the In one case an RCA that originated from the circumflex system instead of the aorta was foundcircumflex system instead of the aorta was found

In another, an uncharacteristically small RCA In another, an uncharacteristically small RCA supplying the patient’s inferior wall was foundsupplying the patient’s inferior wall was found

Conclusions (cont.)Conclusions (cont.)

So, overall, So, overall, 8282Rb PET/CT myocardial Rb PET/CT myocardial perfusion imaging is an accurate and perfusion imaging is an accurate and efficient diagnostic tool for detecting life-efficient diagnostic tool for detecting life-threatening pathologies in obese patients threatening pathologies in obese patients exhibiting symptoms of CADexhibiting symptoms of CAD

And, this makes everyone happy!And, this makes everyone happy!

Questions?Questions?