127Even though the reporter-gene imaging is still mostly limited to animal model
studies the genetic labeling holds promise towards deciphering subcellular mecha-
nisms that take place within therapeutic cells. Also, further studies need to be done
to establish an approach that is practical and can be used within clinical setting.
8.5 Cardiac Imaging for Functional Effects of Stem Cell
Therapy
Cardiac Imaging can be used to evaluate the functional changes following stem cell
therapy. This mainly includes changes in left ventricular (LV) function, myocardial
perfusion, infarct size and myocardial viability. A summary of various imaging tech-
niques used to study the functional effect of stem cell therapy is provided in Table 8.1.
8.5.1 LV Function
Multiple studies have suggested changes in LV function following stem cell therapy.
This includes studies in patients with acute myocardial infarction and chronic isch-
emic heart disease. Although the results for some studies remained inconclusive
[ 48 , 49 ] several studies including work at the authors’ institution suggest some
improvement in LV function post stem-cell therapy [ 19 , 50 – 52 ]. While multiple
imaging modalities have been employed for evaluation of LV function, including
LV angiography, 2-dimensional echocardiography, gated SPECT and MRI, gated
SPECT and MRI are probably the most accurate modalities for assessment of LVEF
and LV volumes. The global improvement of LVEF in these studies was mainly
related to an improvement of regional LV function in the infarct zone, although
improvement along the infarction border zone has also been reported. For most
studies left ventricular end diastolic volume did not change suggesting absence of
reverse modeling. A variation in time course of LV function was also noted in
BOOST study [ 53 ] which showed that the improvement in LV function did not per-
sist for a longer duration of time and beyond 18 months there was no difference
when compared to the control group.
8.5.2 Infarct Size
Various cardiac imaging modalities have been used post stem cell transplant to eval-
uate the infarct size [ 51 , 53 , 54 , 56 ]. These studies include both patients with acute
myocardial infarction as well as chronic ischemic heart disease. Most studies evalu-
ated the infarct size between 3 and 18 months time period using either direct
8 Cardiac Imaging and Stem Cell Transplantation