TEST-RETEST REPRODUCIBILITY OF PET-CT USING RADIOLABELLED WATER (H2[15]O) IN PATIENTS WITH NON-SMALL-CELL LUNG CANCER

With the arrival of molecular-targeted therapeutics for cancer treatment,
questions arise which tool is best for response monitoring. The most promising
drugs in this category target VEGF and/or EGFR and are also called antivascular
or antiangiogenic agents. Since these agents do not regularly result in cell
kill, their effect results in consolidation of the tumor mass rather than
regression. Therefore, the standard volumetric approach (RECIST) is not
suitable. H2[15]O PET-CT offers the opportunity to measure tumor blood flow,
and seems to be a perfect tool to monitor response and effects to these new
agents. To interpret future results, test-retest reproducibility needs to be
known. In the oncological setting only two inhalation PET studies have been
performed in a limited number of patients and range of tumors (mainly hepatic
lesions). Test-retest results of hepatic tumors cannot be directly translated
to tumors of other origin, due to their dual blood supply. Integrated PET-CT
allows to perform a H2[15]O PET-CT study in approximately 30 minutes. This
minimizes patient burden when compared to a *traditional* PET-scanner where,
besides a transmission scan, a tissue-accumulating tracer is needed for
adequate ROI definition, adding 70 minutes to the acquisition protocol.

To measure the test-retest reproducibility of tumor blood flow and associated
measurements as measured with H2[15]O PET-CT in patients with non-small-cell
lung cancer.

A prospective study in 20 patients with NSCLC who will be scanned twice on one
day with a minimal time-interval of four hours without intervening therapy. The
dynamic H2[15]O PET scan will be preceded by a low-dose thoracic CT scan for
photon attenuation correction and ROI definition. A venous cannula will be
inserted for administration of the PET tracer. Total scan time will be 60
minutes (2 x 30 minutes).

The venous cannula can cause a hematoma.

The effective dose equivalent of 1100 MBq H2[15]O is 1.2 mSv, while the
low-dose thoracic CT scan accounts for 0.9 mSv. The total delivered dose will
be 4.2 mSv for both scans (2.1 mSv per scan). The average annual radiation load
per person in the Netherlands from the environment measures 2.3 mSv.