Introduction & Objectives
Prostate cancer treatment is shifting from radical to focal therapy. Instant tumor visualization on a microscopic level is crucial for clinical application of focal therapy. Optical Coherence Tomography (OCT) produces instant tissue visualization on a µm scale. OCT also provides the attenuation as a measure of tissue organization. The objective is to correlate qualitative and quantitative OCT analysis with histopathology.
Material & Methods
Twenty prostates were analyzed by needle based OCT after radical prostatectomy. For precise correlation, whole mount histology slides were cut through the OCT trajectory. OCT images were classified in one of eight histological categories (RvK). Two reviewers (AS & BM) independently performed assessments of the OCT images into these categories. Sensitivity and specificity for detection of malignancy on OCT were calculated. Quantitative attenuation coefficient was found to discriminate stroma and malignant tissue. Figure: Correlation of histology and OCT: The arrows in A, B & C indicate the same atrophic cyst. A: Digitized H&E stained whole mount slide with tissue annotation. Both OCT measurement trajectories are visible. B: An OCT scan at the location of the atrophic cyst. C: The longitudinal section of the OCT scan that corresponds with the upper OCT measurement trajectory shown on A.
Visual analyses showed that OCT can reliably differentiate between fat, cystic and regular atrophy and benign glands. Differentiation of benign stroma and inflammation and also malignancy Gleason 3 and 4 is more difficult. Sensitivity and specificity for detection of malignancy on OCT were calculated at 77% and 84%. Quantitative analysis by means of the attenuation coefficient for differentiation between stroma and malignancy showed no significant difference (4.39 mm-1 vs. 5.31 mm-1).
One to one correlation of histology and OCT helps us to understand what we see and measure on OCT. Visual malignancy detection shows reasonable sensitivity and specificity. Our future studies focus on improving discrimination of malignancy with OCT for example by combining an extra imaging modality.