Ashima Chander1, Peeyush Dhagat2, Debraj Sen3, Harkirat Singh4
BACKGROUND
The differentiation of tumour progression from treatment-induced changes is
critical in evaluating response to therapy among patients with gliomas. Although
conventional magnetic resonance imaging (MRI) is invaluable in the overall
assessment of such lesions, it is often difficult to differentiate between these two
entities. We wanted to evaluate the role of contrast-enhanced MRI (CE MRI) and
magnetic resonance spectroscopy (MRS) and correlation with 99 m Tc Sestamibi
single-photon emission tomography (SPECT) in differentiating tumour progression
from post-therapy changes in patients with glioma.
METHODS
This was a cross-sectional study. Being a rare disease, all adult patients (25 in
number) with brain glioma reporting to the hospital for over a period of 12 months
were included in the study. CE MRI, MRS and SPECT were performed at three
months, six months and 12 months’ post-surgery and radiotherapy. The ratios for
choline (Cho) / N-acetyl aspartate (NAA) and choline (Cho) creatine (Cr) were
obtained from the areas suspicious for tumour progression on CE MRI and were
correlated with the presence or absence of uptake on SPECT. These findings were
correlated with the patients’ clinical course and tumour histopathology.
RESULTS
Both choline (Cho) / N-acetyl aspartate (NAA) and choline (Cho) / creatine (Cr)
ratios had high detection rates for tumour progression when cut-off values of >
1.75 were used. For the Cho / NAA ratio, the sensitivity and specificity were 93.7
% and 100 %, respectively. The sensitivity and specificity for the Cho / Cr ratio
were 81.3 % and 88.9 %, respectively. The sensitivity and specificity of 99 m Tc
Sestamibi SPECT were 87.5 % and 100 %, respectively.
CONCLUSIONS
MRS and SPECT have high sensitivity and specificity for diagnosing tumour
progression and must be used in conjunction with conventional CE MRI in the posttherapy
setting.
