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Theranostics 2016; 6(10):1619-1628. doi:10.7150/thno.15344 This issue Cite

Research Paper

⁶⁸Ga-HBED-CC-PSMA PET/CT Versus Histopathology in Primary Localized Prostate Cancer: A Voxel-Wise Comparison

Constantinos Zamboglou^1✉*, Florian Schiller^2*, Tobias Fechter^1*, Gesche Wieser², Cordula Annette Jilg³, Alin Chirindel⁴, Nasr Salman¹, Vanessa Drendel⁵, Martin Werner⁵, Michael Mix², Philipp Tobias Meyer^2#, Anca Ligia Grosu^1#

1. Department of Radiation Oncology, University Medical Center Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany;
2. Department of Nuclear Medicine, University Medical Center Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany;
3. Department of Urology, University Medical Center Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany;
4. Department of Nuclear Medicine, Claraspital Basel, Switzerland;
5. Department of Pathology, University Medical Center Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.
* Contributed equally to this work
^# Contributed equally to this work

✉ Corresponding author: Constantinos Zamboglou, Department of Radiation Oncology, University Medical Center Freiburg, Germany. Robert-Koch Straße 3, D-79106 Freiburg. Telephone: +4976127094620 Telefax: +497612709582039670 Email: constantinos.zambogloude. More

Abstract

Purpose: We performed a voxel-wise comparison of ⁶⁸Ga-HBED-CC-PSMA PET/CT with prostate histopathology to evaluate the performance of ⁶⁸Ga-HBED-CC-PSMA for the detection and delineation of primary prostate cancer (PCa).

Methodology: Nine patients with histopathological proven primary PCa underwent ⁶⁸Ga-HBED-CC-PSMA PET/CT followed by radical prostatectomy. Resected prostates were scanned by ex-vivo CT in a special localizer and histopathologically prepared. Histopathological information was matched to ex-vivo CT. PCa volume (PCa-histo) and non-PCa tissue in the prostate (NPCa-histo) were processed to obtain a PCa-model, which was adjusted to PET-resolution (histo-PET). Each histo-PET was coregistered to in-vivo PSMA-PET/CT data.

Results: Analysis of spatial overlap between histo-PET and PSMA PET revealed highly significant correlations (p < 10^-5) in nine patients and moderate to high coefficients of determination (R²) from 42 to 82 % with an average of 60 ± 14 % in eight patients (in one patient R² = 7 %). Mean SUVmean in PCa-histo and NPCa-histo was 5.6 ± 6.1 and 3.3 ± 2.5 (p = 0.012). Voxel-wise receiver-operating characteristic (ROC) analyses comparing the prediction by PSMA-PET with the non-smoothed tumor distribution from histopathology yielded an average area under the curve of 0.83 ± 0.12. Absolute and relative SUV (normalized to SUVmax) thresholds for achieving at least 90 % sensitivity were 3.19 ± 3.35 and 0.28 ± 0.09, respectively.

Conclusions: Voxel-wise analyses revealed good correlations of ⁶⁸Ga-HBED-CC-PSMA PET/CT and histopathology in eight out of nine patients. Thus, PSMA-PET allows a reliable detection and delineation of PCa as basis for PET-guided focal therapies.

Keywords: Prostate cancer, PSMA PET/CT, voxel-wise, histopathology, SUV.

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