3D skeletal uptake of 18F sodium fluoride in PET/CT images is associated with overall survival in patients with prostate cancer

Abstract

BackgroundSodium fluoride (NaF) positron emission tomography combined with computer tomography (PET/CT) has shown to be more sensitive than the whole-body bone scan in the detection of skeletal uptake due to metastases in prostate cancer. We aimed to calculate a 3D index for NaF PET/CT and investigate its correlation to the bone scan index (BSI) and overall survival (OS) in a group of patients with prostate cancer.MethodsNaF PET/CT and bone scans were studied in 48 patients with prostate cancer. Automated segmentation of the thoracic and lumbar spines, sacrum, pelvis, ribs, scapulae, clavicles, and sternum were made in the CT images. Hotspots in the PET images were selected using both a manual and an automated method. The volume of each hotspot localized in the skeleton in the corresponding CT image was calculated. Two PET/CT indices, based on manual (manual PET index) and automatic segmenting using a threshold of SUV 15 (automated PET15 index), were calculated by dividing the sum of all hotspot volumes with the volume of all segmented bones. BSI values were obtained using a software for automated calculations.ResultsBSI, manual PET index, and automated PET15 index were all significantly associated with OS and concordance indices were 0.68, 0.69, and 0.70, respectively. The median BSI was 0.39 and patients with a BSI >0.39 had a significantly shorter median survival time than patients with a BSI <0.39 (2.3 years vs not reached after 5 years of follow-up [p = 0.01]). The median manual PET index was 0.53 and patients with a manual PET index >0.53 had a significantly shorter median survival time than patients with a manual PET index <0.53 (2.5 years vs not reached after 5 years of follow-up [p < 0.001]). The median automated PET15 index was 0.11 and patients with an automated PET15 index >0.11 had a significantly shorter median survival time than patients with an automated PET15 index <0.11 (2.3 years vs not reached after 5 years of follow-up [p < 0.001]).ConclusionsPET/CT indices based on NaF PET/CT are correlated to BSI and significantly associated with overall survival in patients with prostate cancer.

Artificial intelligence‐based versus manual assessment of prostate cancer in the prostate gland: a method comparison study

“…In the last few years, convolutional neural networks (CNNs) have revolutionized the field of image analysis, and they are now the first option for image classification, detection and segmentation. CNNs have already been trained to accurately segment organs in CT (Lindgren Belal et al ., ; Roth et al ., ). However, due to misalignment between the PET and CT modalities, a direct transfer of a CT‐based prostate segmentation to the PET image often leads to voxels in the bladder being incorrectly classified as prostate.…”

“…The proposed method requires approximate knowledge of the position of the prostate in CT. This is achieved by first running a simple segmentation network on the CT image (Lindgren Belal et al ., ; Roth et al ., ). Figure shows the overall structure of our CNN.…”

“…In patients with bone metastases, the use of the automated bone scan index is now a validated prognostic biomarker (Armstrong et al ., ). With the increasing use of positron emission tomography/computed tomography (PET/CT), methods for automated volumetric calculations of bone metastatic burden are emerging (Lindgren Belal et al ., ) and direly needed as manual segmentation and determination are both very time‐consuming and observer‐dependent. Imaging is frequently known as a biomarker in patients with disseminated disease, but little is known about this approach in patients undergoing treatment with curative intent.…”

18F-NaF PET/CT IMAGING IN FIBROUS DYSPLASIA OF BONE

“…The optimal SUV threshold values for application of 18 F‐NaF PET/CT have not been standardized and should be determined based on the underlying pathologic condition and the goals of the evaluation. In several oncologic studies of patients with prostate cancer, researchers used an SUV threshold > 15 for 18 F‐NaF uptake to segment bone metastases . In other oncologic studies utilizing 18 F‐NaF PET/CT scans to evaluate metastatic diseases from a variety of cancer types, an SUV threshold of > 10 was applied .…”

Functional and Hybrid Imaging of Bone Metastases

“…The measurement of total skeletal metastatic burden is possible with 18F‐fluoride PET as there is generally high contrast between metastases and normal bone. In prostate cancer, a number of studies have shown that global quantitative metrics can predict treatment response and progression‐free survival or overall survival …”