Table 3.
Application of PET radiotracers for the detection of hypoxia in patients with PDAC.
| PET Radiotracer | Patients with Pancreatic Cancer | Hypoxia-Related Parameter(s) | Other Parameters | Hypoxic Fraction | Other Associations | Ref. |
|---|---|---|---|---|---|---|
| 18F-FMISO | Seven patients with PDAC | SUVmax and TBR (considering background uptake in skeletal muscle) |
18F-FDG PET/CT imaging to demarcate the tumor zone. CT or MRI in non-distinguishable tumors to identify a suitable ROI |
28% increased uptake values | - No association between 18F-FMISO SUVmax or TBR with tumor size, histological type or metabolic activity. | [134] |
| 25 patients with PDAC | Peak tumor–blood ratio: SUVpeak of 18F-FMISO in the tumor divided by SUVpeak of the aorta | Tumor ROIs were manually registered by two nuclear medicine physicians IHC of HIF-1α in 22 patients |
36% visually positive for 18F-FMISO | - Patients with high peak tumor–blood ratio experienced worse RFS and OS. - Ratio not associated with HIF-1α. |
[135] | |
| 18F-HX4 | 13 patients with PDAC | TBRmax: SUVmax in the VOI divided by average SUV in the aorta. VOI and HV: all voxels in the tumor VOI with a TBR > 1 |
- | High repeatability of the amount and location of elevated 18F-HX4 uptake | - TBRmax values were more stable compared to the SUVmax and they varied by 16%. | [136] |
| 18F-FAZA | 20 patients with locally advanced or metastatic PDAC (four cases with both primary tumor and liver metastasis were evaluated) | HF: percentage of voxels with SUVs more than three standard deviations from the mean SUV of skeletal muscle, as obtained from two-hour static scans | Tumor perfusion: based on tracer kinetics by acquiring dynamic scans minutes after the injection of 18F-FAZA and applying a two-compartment model, including blood and extravascular space, under the assumption that pancreatic tumors have low perfusion (flow limited). | Heterogeneity in the HF ranged from values less than 5% to those greater than 50% | - No correlation with tumor volume or perfusion. - Similar 18F-FAZA SUV reported in primary and metastatic tumors. - A trend of higher HF in primary tumors in patients with metastasis than those who are metastasis-free. |
[137] |
FMISO: fluoromisonidazole; FAZA: fluoroazomycin–arabinofuranoside; HX4: flortanidazole; SUVmax: maximum standardized uptake value; TBR: tumor-to-background ratio; ROI: region of interest; VOI: volume of interest; HV: hypoxic volume; HF: hypoxic fraction.