CT/Ultrasound Fusion, a novel sampling technique of ovarian biopsy
Improving patient stratification is a major challenge in high-grade serous ovarian cancer (HGSOC) where both genomic and tumour microenvironment heterogeneity is found within and between patients. High genomic heterogeneity is associated with reduced progression-free survival. In a recent study, researchers have developed a novel precision tissue sampling technique that co-registers CT-based radiomics–based tumour habitats with Ultrasound (US) images in the clinical routine for patients with HGSOC. The research has been published in the journal European Radiology on December 14, 2020.
MRI or CT/US fusion biopsies are an emerging technique to selectively target areas of interest. MRI/US fusion biopsies improve the accuracy to detect especially clinically significant prostate cancer while decreasing the detection of low-grade cancers. MRI or CT/US fusion systems are increasingly used to target hepatic lesions as they increase the accuracy to target tumours that are undetectable with US alone. So far no studies have applied imaging-guided US fusion biopsies in patients with HGSOC. Therefore researchers of the Cancer Research UK Cambridge Centre, University of Cambridge, conducted a study to develop a precision tissue sampling technique that uses computed tomography (CT)–based radiomic tumour habitats for ultrasound (US)-guided targeted biopsies that can be integrated with the clinical workflow of patients with high-grade serous ovarian cancer (HGSOC).
It was a prospective study in Six patients with suspected HGSOC scheduled for US-guided biopsy before starting neoadjuvant chemotherapy from September 2019 to February 2020. Researchers performed the tumour segmentation manually on the pre-biopsy contrast-enhanced CT scan. They used spatial radiomic maps to identify tumour areas with similar or distinct radiomic patterns, and tumour habitats were identified using the Gaussian mixture modelling. CT images with superimposed tumour habitat maps were then co-registered with ultrasound data using Smart Fusion software. They used the dice similarity coefficient (DSC) to assess the tumour-specific CT/US fusion accuracy.
A gynecological radiologist utilized the fused images to perform an ultrasound-guided biopsy on all six participants using an ultrasound scanner with a 3.5-MHz convex transducer. Up to six biopsies -- two per tumour habitat -- were collected for each patient, according to the researchers. They noted that the median time between CT scan and biopsy was 21 days (range 7–30 days) and the median DSC for tumour-specific CT/US fusion accuracy was 0.53. They found that CT/US fusion accuracy was high for the larger pelvic tumours (DSC: 0.76–0.79) while it was lower for the smaller omental metastases.
The authors concluded, "We developed a precision tissue sampling technique that uses radiomic habitats to guide in vivo biopsies using CT/US fusion and that can be seamlessly integrated in the clinical routine for patients with HGSOC".
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