The role of functional imaging in developing strategies towards a patient-tailored approach in prostate cancer


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Karin Haustermans1
1University Hospital, Leuven, Belgium

Abstract

Purpose

To investigate functional imaging modalities for nodal staging and for localizing intraprostatic lesion(s) (IPL) in prostate cancer (PCa).

Materials and Methods

Patients with a risk ≥10% but <35% of lymph node (LN) metastases (Partin) with a negative CT-scan, were prospectively enrolled in an imaging study consisting of a pelvic MRI and a 11C-choline PET-CT. All patients underwent a radical prostatectomy with a superextended LN dissection, including a sentinel node (SN) procedure. Histopathology served as the gold standard.

Results

Seventy-five patients were enrolled of which 34 patients were node positive (N+). As for LN staging, preliminary results show a sensitivity of 9.4% for choline PET-CT (n=36) and 9.5% for Diffusion Weighted (DW) MRI (n=65). Specificity and NPV were high (99.7% and 91.0% for choline PET-CT and 97.6% and 89.6% for DW MRI). A region-based analysis of the SN procedure showed 74 N+ regions of which only 42 regions held a SN. If a SN was present, it was affected in 93% of the cases (39/42). When regions without SN are regarded as false negatives, sensitivity decreased to 53% (39/74).

As for choline PET-CT at the level of the primary tumor, a maximal accuracy of 63% was reached for localizing IPLs with a SUVmax cutoff of 4.5 (n=73). When comparing T2-weigthed, dynamic contrast-enhanced and DW MRI with histopathology, the highest sensitivity was obtained with DW MRI and sensitivity further improved when all modalities were combined.

Conclusion

Nor functional imaging nor the SN procedure can be implemented in daily practice for nodal staging in PCa due to its low sensitivity. As for the primary tumor, multimodality MRI significantly improved IPL detection and localization as compared to each MRI modality alone. The additional value of 11C-choline PET-CT in IPL detection is limited.