Imaging in Stem Cell Transplant and Cell-based Therapy

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used both left ventricular angiography and echocardiography to estimate LVEF
[ 47 ]. Interestingly, Traverse et al. reported that in their MRI laboratory, LVEF mea-
sured by MRI was 5–10% higher compared with LVEF measured by echocardiog-
raphy, highlighting a quantitative difference in assessment of cardiac parameters
that is based on the choice of imaging technique [ 76 ]. In this regard, several studies
that utilized more than one imaging modality also reported data from these dissimi-
lar techniques at various time-points. A comparative review of these numbers reveal
that despite minor differences, results were consistent across multiple modes of
imaging, thereby indicating no major or significant impact of the mode of imaging
on study conclusions [ 26 , 47 , 67 ]. These observations are consistent with the results
from studies that compared the accuracy of various cardiac imaging and reported a
high degree of correlation among CT, echocardiography and MRI [ 89 ].
In order to determine whether the outcomes of BMC therapy were influenced by
imaging techniques in clinical trials, we performed subgroup analysis based on data
from LVG, echocardiography, SPECT and MRI (Table 9.3) [ 19 ]. Interestingly, our
results showed that BMC therapy improved LVEF compared with controls when
measured by echocardiography, LVG and MRI, but not SPECT. Similarly, LVESV
was significantly reduced by BMC therapy when measured by echocardiography,
LVG and MRI, but not SPECT. Infarct size was significantly decreased by SPECT
analysis but not by MRI. LVEDV decreased significantly in BMC-treated patients
when measured by echocardiography and SPECT, but not LVG and MRI. However,
it is important to note that data from these diverse modalities are directionally con-
cordant. Overall, these subgroup analyses indicate that BMC therapy improves car-
diac function when measured by all imaging techniques, even though statistical
significance was not reached for some parameters with certain modes of imaging
perhaps due to smaller patient numbers.

Table 9.2 Relative advantages and disadvantages of imaging modalities used in clinical trials of
bone marrow cell therapy

Mode of imaging Advantages Disadvantages

Echocardiography Easy availability,

reproducibility, good

correlation with MRI data

Potential inter- and intra-observer

variability

Left ventriculography Easy to perform during index

procedure of cell

transplantation

Invasive procedure, inconvenient for

serial assessment of cardiac

function. Potential inter- and

intra-observer variability

SPECT Superior pixel-based

quantitative data for infarct

size measurement

Radiation exposure. Gated data for

volumetric assessment could be

influenced by the underlying rhythm

MRI Accurate volumetric

assessment. Accurate infarct

size assessment at follow up

Less widely available. Difficult to
perform in patients with certain
implanted cardiac devices or other
implants
SPECT single-photon emission computed tomography, MRI magnetic resonance imaging

A. Samanta et al.