Quantification of myocardium at risk in myocardial perfusion SPECT by co-registration and fusion with delayed contrast-enhanced magnetic resonance imaging--an experimental ex vivo study

Clin Physiol Funct Imaging. 2012 Jan;32(1):33-8. doi: 10.1111/j.1475-097X.2011.01051.x. Epub 2011 Sep 22.

Abstract

Background: Myocardial perfusion single-photon emission computed tomography (MPS) can be used to assess myocardium at risk in occlusive coronary ischaemia. The aim was to develop a method to quantify myocardium at risk as perfusion defect size on ex vivo MPS using co-registration and fusion with ex vivo magnetic resonance imaging (MRI).

Methods: Pigs (n = 19) were injected 99mTc-tetrofosmin prior to concluding 40 min of coronary artery occlusion, followed by reperfusion and MRI contrast injection. The excised heart was imaged with T1-weighted MRI and MPS, and images were co-registered using freely available software (Segment v1.8, http://segment.heiberg.se). The left ventricle was semi-automatically delineated in MRI and copied to MPS. The threshold for a MPS perfusion defect was defined as the mean counts in the MPS image at the MRI-determined border between remote myocardium and air. The threshold was measured using count maxima set to the 100th-95th percentile of counts within the myocardium. The count maximum that gave the lowest threshold variability (SD) was considered the most robust.

Results: A count maximum using the 100th percentile yielded a threshold of (mean ± SD) 55 ± 6·2%. This method showed the lowest SD compared to 99th-95th percentile count maxima (6·6-7·2%).

Conclusions: We describe a method for objective quantification of myocardium at risk as perfusion defect size on MPS using knowledge of the anatomy of the myocardium from co-registered MRI. This enables simultaneous quantification of myocardium at risk by MPS and infarct size by MRI for the evaluation of treatments for myocardial infarction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Contrast Media*
  • Coronary Circulation
  • Coronary Occlusion / complications
  • Coronary Occlusion / diagnosis*
  • Coronary Occlusion / diagnostic imaging
  • Coronary Occlusion / pathology
  • Coronary Occlusion / physiopathology
  • Disease Models, Animal
  • Female
  • Magnetic Resonance Imaging*
  • Male
  • Myocardial Infarction / diagnosis*
  • Myocardial Infarction / diagnostic imaging
  • Myocardial Infarction / etiology
  • Myocardial Infarction / pathology
  • Myocardial Infarction / physiopathology
  • Myocardium / pathology*
  • Organophosphorus Compounds
  • Organotechnetium Compounds
  • Predictive Value of Tests
  • Radiopharmaceuticals
  • Swine
  • Tomography, Emission-Computed, Single-Photon*

Substances

  • Contrast Media
  • Organophosphorus Compounds
  • Organotechnetium Compounds
  • Radiopharmaceuticals
  • technetium tc-99m tetrofosmin