Patients with brain tumors are routinely monitored for tumor progression an
d response to therapy using magnetic resonance imaging (MRI). Although seri
al changes in gadolinium enhancing lesions provide valuable information for
making treatment decisions, they do not address the fate of non-enhancing
lesions and are unable to distinguish treatment induced necrosis from resid
ual or recurrent tumor. The introduction of a non-invasive methodology, whi
ch could identify an active tumor more reliably, would have a major impact
upon patient care and evaluation of new therapies. There is now compelling
evidence that magnetic resonance spectroscopic imaging (MRSI) can provide s
uch information as an add-on to a conventional MRI examination. We discuss
data acquisition and analysis procedures which are required to perform such
serial MRI-MRSI examinations and compare their results with data from hist
ology, contrast enhanced MRI, MR cerebral blood volume imaging and FDG-PET.
Applications to the serial assessment of response to therapy are illustrat
ed by considering populations of patients being treated with brachytherapy
and gamma knife radiosurgery. Copyright (C) 1999 John Wiley & Sons, Ltd.