Skeletal 18F-PSMA-1007 uptake in prostate cancer patients

Jorinde Janssen; Walter Noordzij; Ton Velleman; Igle Jan de Jong; Johannes A Langendijk; J Fred Verzijlbergen; Gilles N Stormezand; Shafak Aluwini

doi:10.1177/17588359231179311

Skeletal ¹⁸F-PSMA-1007 uptake in prostate cancer patients

Ther Adv Med Oncol. 2023 Jun 29:15:17588359231179311. doi: 10.1177/17588359231179311. eCollection 2023.

Authors

Jorinde Janssen¹, Walter Noordzij², Ton Velleman², Igle Jan de Jong³, Johannes A Langendijk⁴, J Fred Verzijlbergen⁵, Gilles N Stormezand², Shafak Aluwini⁴

Affiliations

¹ Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, Groningen 9713GZ, The Netherlands.
² Department of Radiology and Nuclear Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
³ Department of Urology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
⁴ Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
⁵ Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.

Abstract

Background/objectives: Accurate and uniform interpretation and reporting of metastatic prostate cancer (PCa) lesions on prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) are indispensable. ¹⁸F-PSMA-1007 is increasingly used because of its favorable imaging characteristics. However, increased non-specific skeletal uptake may be an important pitfall of this radioligand. Therefore, we aimed to assess the interobserver variation in reporting skeletal ¹⁸F-PSMA-1007 uptake on PET/CT.

Design/methods: In total, 33 ¹⁸F-PSMA-1007 PET/CT scans of 21 patients with primary PCa and 12 patients with biochemical recurrence were included, and a total of 85 skeletal lesions were evaluated by three independent observers. The primary endpoint was the interobserver variability of the likelihood of malignancy of the skeletal lesions on both patient and lesion level (kappa analysis).

Results: Observers qualified most lesions as not malignant (81-91%) and the overall mean interobserver agreement was moderate on both patient (κ: 0.54) and lesion level (κ: 0.55). In 52 lesions without corresponding CT substrate, the rating resulted in not malignant in 95-100%. Availability of additional imaging (60% of lesions) did not improve interobserver agreement (κ: 0.39 on lesion level) and resulted in unchanged rating for all observers in 78%.

Conclusion: This interobserver analysis of skeletal ¹⁸F-PSMA-1007 uptake resulted in moderate agreement, in line with rates reported in literature. Importantly, the presence of non-specific skeletal uptake without CT substrate, as a potential shortcoming of ¹⁸F-PSMA-1007, did not impair interobserver agreement.

Keywords: 18F-PSMA-1007; PSMA PET/CT; interobserver agreement; prostate cancer; skeletal uptake.