Cardiac Case Study 2

Summary

Patient History
Patient is a 59 year old female who presented with a single episode of chest pain, dizziness, diaphoresis, and lightheadedness. The patient had no prior history of any previous episodes of this type. There was no prior history of chest pain on exertion. Height: 65 inches; weight: 210 lbs.
Imaging Procedure
The One Day Cardiolite Protocol was used, and rest imaging was performed first. Imaging was done on a GE Millennium Dual Head Camera with 36 stops/detector, 180 degrees.

Acquisition Parameters:

  Type of Acquisition Time per stop Agent Dose Injection-Image Interval
Rest Ungated SPECT 35 seconds 99m Tc Sestamibi 8.9 mCi 45 minutes after injection
Stress Gated SPECT 30 seconds 99m Tc Sestamibi 31 mCi 40 minutes after injection

Target heart rate (85% of maximum heart rate): 136 bpm. Maximal heart rate achieved on treadmill: 147 bpm.

> GE Millennium Dual Head Camera


Imaging Analysis

Both the rest and stress studies were count rich. Stress counts within a circular ROI over the heart were 13,228; stress maximum pixel value was 134. Rest counts were 9881; rest maximum pixel value was 85. The guideline for an adequate count study for this many projection images is to have 2500 or more counts within a tight circular ROI around the epicardial edge of the myocardium on an anterior view. The maximum pixel value within this ROI should be at least 50 counts. These values can be automatically determined in the MyoSPECT protocol.

Both the rest and stress projection images show some attenuation. The slices were reconstructed using the Cardiac SPECT Protocol. Both the rest and stress short axis images show a decrease of counts in the anterior wall. The counts in the anterior wall of the vertical long axis images are also diminished.
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Note: Reconstruction and reformatting could have been done by QGS/QPS, Cardiac SPECT, or the ECToolbox (they all use the same format) or by the MyoSPECT protocol.



The data was first processed with the CEqual option of the ECToolbox. The fixed nature of the anterior defect is clearly seen in the CEqual plots. However, the standard deviation plots show that these defects are not very severe, only two to three SD below normal. 		qgs plots

Further, the results from Perfex TM , an ECToolbox option available from the plot review, show that the defects are not statistically significant. Perfex also provides an impression of a normal scan with high confidence.

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The beating slices for this patient thicken and brighten normally at systole. When a perfusion defect is not visible consistently at both diastole and systole, it is more likely to be an attenuation artifact than a true defect. (DePuey; 1994)

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The data was then processed with QGS to give additional functional and 3D information. QGS will use as input the slices created in the ECToolbox. There is no need to reconstruct the data in QGS. The left ventricular function appeared normal.

The ES Perfusion Map shows good perfusion in the anterior wall at end systole. Normal function would strongly favor breast attenuation as a cause of the anterior fixed defect. (DePuey and Rozanski; 1995)
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MyoSPECT was then used for additional information. Since the slices were already created, there was no need to reconstruct them in MyoSPECT. The 3D surfaces visually reinforce the artifactual nature of the defect since they show no defect in the anterior wall.

The beating plot created from the stress gated images also shows that the defect is not present at end-systole.

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EKG Results:

There was adequate and appropriate blood pressure response to exercise. There weren't any exercise induced ischemic repolarization changes or any significant arrhythmias. (EKG results courtesy of Oconomowoc Memorial Hospital)

Findings:

There wasn’t any evidence of stress induced myocardial ischemia. The left ventricular function was normal. There was mild diminished perfusion in the anterior wall consistent with breast attenuation. (Findings courtesy of Oconomowoc Memorial Hospital)

References:

  1. Robert C. Hendel, Raymond J. Gibbons, and Timothy M. Bateman. "Use of rotating (cine) planar projection images in the interpretation of a tomographic myocardial perfusion study." J Nucl Cardiol 1999; 6:234-240.
  2. E. Gordon DePuey and Alan Rozanski. "Using gated Technetium-99m-Sestamibi SPECT to characterize fixed myocardial defects as infarct or artifact." J Nucl Med 1995; 36:952-955.
  3. E. Gordon DePuey. "How to detect and avoid myocardial perfusion SPECT artifacts". J Nucl Med 1994; 35:699-702.


Images Courtesy of:

Oconomowoc Memorial Hospital,
Oconomowoc, WI