Novel mammogram-based measures improve breast cancer risk prediction beyond an established mammographic density measure

Mammograms contain information that predicts breast cancer risk. We developed two novel mammogram-based breast cancer risk measures based on image brightness (Cirrocumulus) and texture (Cirrus). Their risk prediction when fitted together, and with an established measure of conventional mammographic density (Cumulus), is not known. We used three studies consisting of: 168 interval cases and 498 matched controls; 422 screen-detected cases and 1197 matched controls; and 354 younger-diagnosis cases and 944 controls frequency-matched for age at mammogram. We conducted conditional and unconditional logistic regression analyses of individually- and frequency-matched studies, respectively. We estimated measure-specific risk gradients as the change in odds per standard deviation of controls after adjusting for age and body mass index (OPERA) and calculated the area under the receiver operating characteristic curve (AUC). For interval, screen-detected and younger-diagnosis cancer risks, the best fitting models (OPERAs [95% confidence intervals]) involved: Cumulus (1.81 [1.41-2.31]) and Cirrus (1.72 [1.38-2.14]); Cirrus (1.49 [1.32-1.67]) and Cirrocumulus (1.16 [1.03 to 1.31]); and Cirrus (1.70 [1.48 to 1.94]) and Cirrocumulus (1.46 [1.27-1.68]), respectively. The AUCs were: 0.73 [0.68-0.77], 0.63 [0.60-0.66], and 0.72 [0.69-0.75], respectively. Combined, our new mammogram-based measures have twice the risk gradient for screen-detected and younger-diagnosis breast cancer (P ≤ 10^-12 ), have at least the same discriminatory power as the current polygenic risk score, and are more correlated with causal factors than conventional mammographic density. Discovering more information about breast cancer risk from mammograms could help enable risk-based personalised breast screening.

Reproducibility of choroidal thickness measurements in subjects on 3 spectral domain optical coherence tomography machines

The purpose of this study was to investigate the reproducibility of choroidal thickness measurements in normal subjects on 3 spectral domain optical coherence tomography instruments, namely: Zeiss Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA), Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany), and Optovue RTVue (Optovue Inc., Fremont, CA). This cross-sectional non-interventional study was performed in a single institution. Images were obtained in 47 eyes of 47 healthy volunteers which age ranged between 23 and 72 without ocular pathology. All subjects were imaged on the fovea using Cirrus HD 1-line raster, Spectralis enhanced depth imaging, and RTVue retina-cross. The choroid was measured subfoveally and at intervals of 500 µm from the fovea nasally and temporally up to 2500 µm. Paired t test, modified Bland-Altman plot, and Pearson's correlation were used to compare the results. There is no significant difference between the systems for any measurement within 2500 µm either side of the fovea for most points. Inter-observer correlation was strong for RTVue, and moderate in both Cirrus and Spectralis.

Repeatability of peripapillary retinal nerve fiber layer and inner retinal thickness among two spectral domain optical coherence tomography devices

PURPOSE

To compare measurement of macular inner retina and peripapillary retinal nerve fiber layer (pRNFL) thickness using two spectral-domain optical coherence tomography (SD-OCT) devices in glaucoma patients, patients with ocular hypertension, idiopathic and atypical Parkinson disease, and healthy controls.

METHODS

A total of 171 eyes of 146 participants underwent successful pRNFL and macular scanning and automated measurement of ganglion cell layer+inner plexiform layer (GCL-IPL) using Cirrus HD-OCT or retinal nerve fiber layer+GCL-IPL (RNFL-GCL-IPL) using RTVue-100. Macular RNFL was added to the GCL-IPL thickness measured by Cirrus and was compared to the RNFL-GCL-IPL thickness of the RTVue in the corresponding Cirrus sectors. Intraclass correlation coefficient (ICC) was calculated to determine repeatability of three consecutive measurements; ICC and Bland-Altman analysis to assess agreement between OCTs; Pearson's correlation coefficient to assess strength of linear correlation.

RESULTS

Repeatability of average macular RNFL-GCL-IPL thickness measurement was excellent with an ICC of 0.998 for Cirrus and 0.995 for RTVue. Repeatability was also good for average pRNFL thickness measurements. Both instruments demonstrated a good consistency in measurements with ICC values ranging from 0.844 to 0.862 for macular RNFL-GCL-IPL and 0.718 to 0.958 for pRNFL thickness.

CONCLUSIONS

Measurement of pRNFL and macular RNFL-GCL-IPL thickness has a high degree of repeatability for both OCT devices. Despite a high correlation between measurements of the two OCT devices and fair to excellent ICC values representing a high consistency in the measurements of the two devices, RTVue measured a thicker macular RNFL-GCL-IPL and pRNFL thickness.

Artifacts in optical coherence tomography

Optical coherence tomography (OCT) is now an integral part of management for numerous retinal diseases for diagnosis, treatment planning and follow up. OCT interpretation must involve the understanding of the associated artifacts. These artifacts can mislead physicians to wrong diagnosis or inappropriate management. This review article discusses the various types of artifacts in OCT scans obtained from various devices in various retinal diseases. This article would help to improve the understanding about the various artifacts and their clinical importance.