215brain tumors showed changes in the diffusion map if chemotherapy or radiation
therapy was having any effect. It worked within 3 weeks, 10 weeks before tradi-
tional MRI techniques of assessing whether therapy is working. Usually, patients
get 7 weeks of treatment, followed by a traditional MRI scan 6 weeks afterwards to
see if the tumor has shrunk. If it does not, the management approach may be altered
depending on the tumor. Speeding up this process can save patients from often-
uncomfortable treatments that may be a waste of time. Use of MRI tumor diffusion
values to accurately predict the treatment response early on could enable some
patients to switch to a more benefi cial therapy and avoid the side effects of a pro-
longed and ineffective treatment. There are plans to test the technique with breast
cancer as well as head and neck cancer.
FDG-PET/CT for Personalizing Cancer Treatment
Multimodality imaging, as represented by PET, has a defi nite role in the evaluation
of a patient with cancer. Fluorodeoxyglucose (FDG)-PET is rapidly becoming the
key investigative tool for the staging and assessment of cancer recurrence. In the last
5 years, PET has also gained widespread acceptance as a key tool used to demon-
strate early response to intervention and therapy, whereas changes in size of tumor
as shown by CT alone may take longer. This clinical need is being addressed with
FDG-PET/CT, because of its inherent ability to demonstrate (before other biomark-
ers of response) if disease modifi cation has occurred (Ben-Haim and Ell 2009 ). This
is an important factor in personalizing cancer treatment.
In non-small cell lung cancer (NSCLC), reduction of metabolic activity as dem-
onstrated by FDG-PET after one cycle of chemotherapy is closely correlates with
fi nal outcome of therapy. Using metabolic response as an end point may shorten the
duration of phase II studies evaluating new cytotoxic drugs and may decrease the
morbidity and costs of therapy in non-responding patients. Another example of a
generic functional imaging method is the use of FDG-PET to look at the response
of gastrointestinal stromal tumor (GIST) to Gleevec. Preliminary studies show
marked decrease of FDG uptake in GIST tumors within 24 h in patients who go on
to show clinical response to Gleevec. PET accurately diagnosed tumor response in
85 % of patients at 1 month and 100 % at 3–6 months whereas CT was found to be
accurate in 44 % of patients at 1 month, 60 % at 3 months, and 57 % at 6 months
(Antoch et al. 2004 ). Radiolabeled annexin V may provide an early indication of the
success or failure of anticancer therapy on a patient-by-patient basis as an in vivo
marker of tumor cell killing. The temporal patterns of tumor cell loss has been dem-
onstrated by SPECT and provides a better understanding of the timing of radiola-
beled annexin V uptake for its development as a biomarker of therapeutic effi cacy.
Abnormal tryptophan metabolism catalyzed by indoleamine 2,3-dioxygenase
may play a prominent role in tumor immunoresistance in many tumor types, includ-
ing lung tumors. Prolonged retention of alpha-(11)C-methyl-l-tryptophan (AMT), a
PET tracer for tryptophan metabolism, in NSCLCs suggests high metabolic rates of
tryptophan in these tumors. AMT PET/CT may be a clinically useful molecular
Impact of Molecular Diagnostics on the Management of Cancer