Optimal 68Ga-PSMA and 18F-PSMA PET window levelling for gross tumour volume delineation in primary prostate cancer

PURPOSE: This study proposes optimal tracer-specific threshold-based window levels for PSMA PET-based intraprostatic gross tumour volume (GTV) contouring to reduce interobserver delineation variability.

METHODS: Nine 68Ga-PSMA-11 and nine 18F-PSMA-1007 PET scans including GTV delineations of four expert teams (GTVmanual) and a majority-voted GTV (GTVmajority) were assessed with respect to a registered histopathological GTV (GTVhisto) as the gold standard reference. The standard uptake values (SUVs) per voxel were converted to a percentage (SUV%) relative to the SUVmax. The statistically optimised SUV% threshold (SOST) was defined as those that maximises accuracy for threshold-based contouring. A leave-one-out cross-validation receiver operating characteristic (ROC) curve analysis was performed to determine the SOST for each tracer. The SOST analysis was performed twice, first using the GTVhisto contour as training structure (GTVSOST-H) and second using the GTVmajority contour as training structure (GTVSOST-MA) to correct for any limited misregistration. The accuracy of both GTVSOST-H and GTVSOST-MA was calculated relative to GTVhisto in the 'leave-one-out' patient of each fold and compared with the accuracy of GTVmanual.

RESULTS: ROC curve analysis for 68Ga-PSMA-11 PET revealed a median threshold of 25 SUV% (range, 22-27 SUV%) and 41 SUV% (40-43 SUV%) for GTVSOST-H and GTVSOST-MA, respectively. For 18F-PSMA-1007 PET, a median threshold of 42 SUV% (39-45 SUV%) for GTVSOST-H and 44 SUV% (42-45 SUV%) for GTVSOST-MA was found. A significant pairwise difference was observed when comparing the accuracy of the GTVSOST-H contours with the median accuracy of the GTVmanual contours (median, - 2.5%; IQR, - 26.5-0.2%; p = 0.020), whereas no significant pairwise difference was found for the GTVSOST-MA contours (median, - 0.3%; IQR, - 4.4-0.6%; p = 0.199).

CONCLUSIONS: Threshold-based contouring using GTVmajority-trained SOSTs achieves an accuracy comparable with manual contours in delineating GTVhisto. The median SOSTs of 41 SUV% for 68Ga-PSMA-11 PET and 44 SUV% for 18F-PSMA-1007 PET form a base for tracer-specific window levelling.

TRIAL REGISTRATION: Clinicaltrials.gov ; NCT03327675; 31-10-2017.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:48

Enthalten in:

European journal of nuclear medicine and molecular imaging - 48(2021), 4 vom: 06. Apr., Seite 1211-1218

Sprache:

Englisch

Beteiligte Personen:

Draulans, Cédric [VerfasserIn]
De Roover, Robin [VerfasserIn]
van der Heide, Uulke A [VerfasserIn]
Kerkmeijer, Linda [VerfasserIn]
Smeenk, Robert J [VerfasserIn]
Pos, Floris [VerfasserIn]
Vogel, Wouter V [VerfasserIn]
Nagarajah, James [VerfasserIn]
Janssen, Marcel [VerfasserIn]
Isebaert, Sofie [VerfasserIn]
Maes, Frederik [VerfasserIn]
Mai, Cindy [VerfasserIn]
Oyen, Raymond [VerfasserIn]
Joniau, Steven [VerfasserIn]
Kunze-Busch, Martina [VerfasserIn]
Goffin, Karolien [VerfasserIn]
Haustermans, Karin [VerfasserIn]

Links:

Volltext

Themen:

9G34HU7RV0
Delineation
Edetic Acid
Focal boost
Gallium 68 PSMA-11
Gallium Isotopes
Gallium Radioisotopes
Journal Article
Oligopeptides
PSMA PET
Prostatic neoplasms
Radiotherapy
Research Support, Non-U.S. Gov't

Anmerkungen:

Date Completed 28.05.2021

Date Revised 04.12.2021

published: Print-Electronic

ClinicalTrials.gov: NCT03327675

Citation Status MEDLINE

doi:

10.1007/s00259-020-05059-4

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM315952733