IMPLICATIONS FOR FALSE POSITIVE ROTATIONAL SPECT RSPECT STUDIES BEING CAUSED BY POSTSTRESS CHANGES I

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IMPLICATIONS FOR FALSE POSITIVE ROTATIONAL SPECT
(RSPECT) STUDIES BEING CAUSED BY POST-STRESS
CHANGES IN CARDIAC VOLUME

• T.P. Bublitz, D.L. Kirch, J.E. Koss, P.P. Steele
• Nuclear Cardiology Research
• Western Cardiology Associates, PC
• Englewood, Colorado

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PREVIOUS INDICATIONS THAT CARDIAC CHAMBER SIZE
CHANGES COULD BE A PROBLEM

• Literature describes dramatic shape and volume
  changes during and following exercise and change
  of position
• Occurrence of unexplainable false positive
  myocardial perfusion studies (specificity in the
  70-80 range)
• Numerous attempts to identify and correct for
  sources of artifacts in RSPECT studies have
  proven inconclusive
• Visual inspection of cine playback of RSPECT
  images
• Ability of NRSPECT to monitor cardiac chamber
  volume changes over a 20-30 min period following
  stress

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METHODOLOGY APPLIED TO SEQUENTIALLY MONITOR
CARDIAC VOLUME CHANGES

• MULTI-PINHOLE NRSPECT IS UNIQUELEY SUITED FOR
  SERIAL MEASUREMENTS
• EXCELLENT STATISTICS PERMIT VOLUME COMPUTATIONS
  TO BE MADE IN THREE MINUTE INTERVALS
• MIDLINE OR CENTER WALL TRACKING USED TO COMPUTE
  VOLUMES
• VISUAL INSPECTION USED TO CORROBORATE THE
  MAGNITUDE AND DIRECTION OF THE COMPUTED CHANGES
• CHAMBER SHAPE CHANGES ARE VISUALLY APPRECIATED

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SIMULTANEOUS DUAL-ISOTOPE (TL-201/TC99m)
MYOCARDIAL PERFUSION IMAGING PROTOCOL

• SETUP IV AND INJECT 6.0 mCi OF Tc AGENT
• PATIENT DRINKS 8-16 oz OF CLEAR LIQUID DURING 10
  min WAIT PRIOR TO EKG HOOK-UP FOR STRESS TEST
• INJECTION OF 4.0 mCi OF Tl-201 OCCURS 1-2 min
  PRIOR TO CESSATION OF STRESS MANEUVRE
• GATED, SIMULTANEOUS DUAL-ISOTOPE IMAGING IS
  PERFORMED IMMEDIATELY FOLLOWING COOL DOWN
• LIST-MODE DATA ACQUISITION TAKES ABOUT 20 MINUTES
  AND RESULTS IN 3 MILLION COUNTS PER VIEW
• TOTAL DURATION OF TEST IS lt 90 min

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MULTI-PINHOLE TOMOGRAPHIC RECONSTRUCTIONS
SHORT AXIS RESTING IMAGES Tc-99m
SHORT AXIS STRESS IMAGES Tl-201
LONG AXIS RESTING IMAGES
LONG AXIS STRESS IMAGES
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CENTER WALL TRACKING PERFORMED ON 8 SHORT AXIS
SLICES FROM APEX TO BASE
CCP CURVES DEVELOPED AT 60 POINTS THROUGH 360o.
SEARCH FOR MAXIMUM VALUE AVERAGED WITH TWO
NEAREST RADIAL NEIGHBORS
APEX
BASE
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CIRCUMFERENTIAL COUNT PROFILE CURVES

STRESS
REST
STRESS-REST DIFFERENCE
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VOLUME IMAGES UNGATED (TOP) GATED (BOTTOM)
RESTING (LATE) VOLUME IMAGES 72cc
STRESS (EARLY) VOLUME IMAGES 77 cc
MID VOL 73cc
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ACUTELY DILATED VOLUME (77 cc TO 72 cc) WITH
INFERIOR LATERAL SHAPE CHANGES
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ACUTELY DIMINISHED VOLUME (113 cc TO 130 cc) WITH
SUPERIOR LATERAL SHAPE CHANGES
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NO VOLUME CHANGES (50 cc TO 52 cc) AND NO
SIGNIFICANT SHAPE CHANGES
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ACUTELY DILATED VOLUME (135 cc TO 126 cc) WITH
SUPERIOR SEPTAL SHAPE CHANGES
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NEGLIGIBLE VOLUME CHANGES (110 cc TO 111cc) WITH
REDISTRIBUTATIVE SIZE CHANGES
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ACUTE VOLUME DILATION (102 cc TO 96 cc) WITH
INFERIOR SHAPE CHANGES
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CORRELATION BETWEEN POST STRESS VOLUME CHANGES
AND RATE-PRESSURE PRODUCT
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CORRELATION BETWEEN POST STRESS VOLUME CHANGES
AND AGE (MEN AND WOMEN COMBINED)
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CORRELATION BETWEEN POST STRESS VOLUME CHANGES
AND AGE (MEN ONLY)
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CORRELATION BETWEEN POST STRESS VOLUME CHANGES
AND AGE (WOMEN ONLY)
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CORRELATION BETWEEN POST STRESS VOLUME CHANGES
AND BODY MASS INDEX
OBESE
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CONCLUSIONS FROM ANALYSIS OF 818 DUAL-ISOTOPE
GATED PERFUSION STUDIES

• THE MEAN VALUE OF LV VOLUME CHANGES IS 4.5
• MAJORITY OF PATIENTS (70) SHOW ACUTE DILATION
  FOLLOWING EXERCISE AND RECLINE FOR IMAGING
• 23.3 OF PATIENTS SHOW DILATION GREATER THE 10
• 3 OF PATIENTS SHOW DIMINATION GREATER THAN -10
• IN 13 OF PATIENTS SHOWING VOLUME CHANGES gt10
  RESOLUTION TO LESS THAN 5 OCCURS BY THE 10 min
  MID-POINT
• SIGNIFICANT VENTRICULAR SHAPE CHANGES CAN OCCUR
  WITH LITTLE CHANGE IN THE COMPUTED VOLUME OF THE
  VENTRICLE
• WE HAVE NOT FOUND ANY PRE- OR POST-TEST CORRELATE
  THAT PREDICTS THE MAGNITUDE OF THESE CHANGES
• SEQUENTIAL STUDIES ON THE SAME PATIENT ARE
  UNPREDICTABLE

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Study Comparison
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CINE DISPLAY OF TWO SUCCESSIVE RESTING IMAGES
ACQUIRED BACK-TO-BACK
RESTING DATA SET
PSEUDO STRESS DATA SET
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CINE DISPLAY OF FRAMES 31 AND 32
These are the transitional frames acquired by
detector 1 and detector 2
RESTING STUDY PSEUDO STRESS
STUDY
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