One of the principal hallmarks of cancer is angiogenesis [
1], which leads to increased blood flow in the tumor. Tumor blood flow (TBF) imaging has therefore previously been studied for characterization and treatment response evaluation in various cancers, including non-small cell lung cancer [
2,
3], breast cancer [
4‐
7], head and neck cancer [
8], colorectal cancer [
3,
9], brain cancer [
10], and prostate cancer [
11‐
13].
15O-H
2O positron emission tomography (PET) is the gold standard method for non-invasive blood flow imaging. Several studies have found a high reproducibility of TBF measurements with
15O-H
2O PET in various cancers [
14‐
17]. Clinical implementation of
15O-H
2O PET is, however, challenging and limited to few PET centers due to the requirement of an on-site cyclotron to produce the short-lived
15O tracer. An alternative flow tracer is the generator-produced potassium analogue
82Rubidium (
82Rb), which is already clinically available for cardiac blood flow measurement at many PET centers worldwide.
82Rb is a retention tracer that allows both kinetic modeling and static analysis of late uptake images using standardized uptake values (SUV). Enhanced
82Rb uptake has previously been described in breast cancer [
18], lung cancer, lymphoma, multiple myeloma [
19], malignant pheochromocytoma [
20], and metastatic renal cell carcinoma [
21]. We have recently demonstrated three novel insights: first, that TBF measures derived from static and dynamic
82Rb PET were highly correlated with
15O-H
2O PET; second, that
82Rb TBF in prostate cancer was significantly larger than blood flow in healthy prostate tissue; and third, that
82Rb TBF correlates with prostate cancer aggressiveness [
22].
The clinical usefulness of TBF measurement with
82Rb PET is highly dependent on the repeatability of the method. To design and interpret active surveillance and treatment response studies, knowledge of the test-retest variability is also required.
82Rb PET has a high reproducibility in quantitative myocardial blood flow assessment [
23]. However, no test-retest data on
82Rb PET on tumors exist. Hence, the aim of the present study was to evaluate the repeatability of TBF measurement with static and dynamic
82Rb PET.