Progression of bone metastases in patients with prostate cancer - automated detection of new lesions and calculation of bone scan index

Abstract

BackgroundThe objective of this study was firstly to develop and evaluate an automated method for the detection of new lesions and changes in bone scan index (BSI) in serial bone scans and secondly to evaluate the prognostic value of the method in a group of patients receiving chemotherapy.MethodsThe automated method for detection of new lesions was evaluated in a group of 266 patients using the classifications by three experienced bone scan readers as a gold standard. The prognostic value of the method was assessed in a group of 31 metastatic hormone-refractory prostate cancer patients who were receiving docetaxel. Cox proportional hazards were used to investigate the association between percentage change in BSI, number of new lesions and overall survival. Kaplan-Meier estimates of the survival function were used to indicate a significant difference between patients with an increase/decrease in BSI or those with two or more new lesions or less than two new lesions.ResultsThe automated method detected progression defined as two or more new lesions with a sensitivity of 93% and a specificity of 87%. In the treatment group, both BSI changes and the number of new metastases were significantly associated with survival. Two-year survival for patients with increasing and decreasing BSI from baseline to follow-up scans were 18% and 57% (p = 0.03), respectively. Two-year survival for patients fulfilling and not fulfilling the criterion of two or more new lesions was 35% and 38% (n.s.), respectively.ConclusionsAn automated method can be used to calculate the number of new lesions and changes in BSI in serial bone scans. These imaging biomarkers contained prognostic information in a small group of patients with prostate cancer receiving chemotherapy.

Computer-assisted interpretation of planar whole-body bone scintigraphy in patients with newly diagnosed prostate cancer

“…The file format issue is relevant when comparing data among sites and in serial scans if different file formats are used.The diagnostic properties of the computer-aided analysis program showed sensitivities and specificities of 90-100% with DICOM format files and 69-88% with Interfile formats. The high sensitivities and specificities are in line with previous reports[9,10,12,17]. Most studies with EXINI Bone BSI have been performed in patients with metastatic disease in whom the prevalence of metastasis varied from 15 to 40%[10,12,15].…”

Analytic Validation of the Automated Bone Scan Index as an Imaging Biomarker to Standardize Quantitative Changes in Bone Scans of Patients with Metastatic Prostate Cancer

“…Variables such as image count corresponding to scanning time and interpatient-dependent attenuation factors can cause noise in BSI interpretations, and this noise can affect the reliability of the on-treatment BSI change as a quantitative biomarker. In previous studies, the on-treatment BSI change has been reported as the percentage of BSI change, BSI doubling time, and BSI difference (5,14,15), but none of the studies have accounted for the noise in BSIs that results from the inherent variability of the bone scan procedure.…”

Use of modern imaging methods to facilitate trials of metastasis-directed therapy for oligometastatic disease in prostate cancer: a consensus recommendation from the EORTC Imaging Group

“…25 . The bone scan index (BSI) carries a prognostic value for estimating survival and the PCWG 3 criteria (two new confirmed lesions = progressive disease (PD)) predict overall survival 98,99,100,101,102,103 . The lack of sensitivity of BS to treatment response, however, exposes patients with short life expectancy to futile and potentially toxic treatment.…”