Conspicuity of microcalcifications on digital screening mammograms using varying degrees of monitor zooming

Evaluation of the effect of zoom function on lesion detection by soft-copy reading of screening mammograms

INTRODUCTION

This study aims to evaluate the effectiveness of zooming in improving screen-reader performance in reporting digital mammograms.

METHOD

Two experiments were conducted. In the first experiment, 5 readers were asked to report 59 two-view bilateral mammograms retrospectively with zooming function turned off. The second session was similar to the first one except that zooming was enabled. The task of readers was to assess if the mammograms were normal or abnormal and rate the confidence levels for each of the lesion they detected. The reader performances were evaluated via case sensitivity, lesion sensitivity, specificity, receiver operating characteristics (ROC) area under the curve (AUC) and jackknife free-response receiver operating characteristics (JAFROC) figure of merit (FOM).

RESULTS

There was no significant improvement in overall reader performance in detecting abnormalities in zooming condition compared with no zooming in terms of case sensitivity (96% and 87%, P = 0.285) or lesion sensitivity (88% and 81%, P = 0.224). However, differences in ROC AUC and JAFROC FOM (P ≤ 0.05) were found in two readers when they performed the test set with zooming function.

CONCLUSION

The results suggested that the use of the zooming function did improve the performance of some readers in detecting abnormal cases.

Human Factors and Human-Computer Considerations in Teleradiology and Telepathology

Radiology and pathology are unique among other clinical specialties that incorporate telemedicine technologies into clinical practice, as, for the most part in traditional practice, there are few or no direct patient encounters. The majority of teleradiology and telepathology involves viewing images, which is exactly what occurs without the "tele" component. The images used are generally quite large, require dedicated displays and software for viewing, and present challenges to the clinician who must navigate through the presented data to render a diagnostic decision or interpretation. This digital viewing environment is very different from the more traditional reading environment (i.e., film and microscopy), necessitating a new look at how to optimize reading environments and address human factors issues. This paper will review some of the key components that need to be optimized for effective and efficient practice of teleradiology and telepathology using traditional workstations as well as some of the newer mobile viewing applications.

Full Field Digital Mammography (FFDM) versus CMOS Technology, Specimen Radiography System (SRS) and Tomosynthesis (DBT) - Which System Can Optimise Surgical Therapy?

Aim: This prospective clinical study aimed to evaluate whether it would be possible to reduce the rate of re-excisions using CMOS technology, a specimen radiography system (SRS) or digital breast tomosynthesis (DBT) compared to a conventional full field digital mammography (FFDM) system. Material and Method: Between 12/2012 and 2/2013 50 patients were diagnosed with invasive breast cancer (BI-RADS™ 5). After histological verification, all patients underwent breast-conserving therapy with intraoperative imaging using 4 different systems and differing magnifications: 1. Inspiration™ (Siemens, Erlangen, Germany), amorphous selenium, tungsten source, focus 0.1 mm, resolution 85 µm pixel pitch, 8 lp/mm; 2. BioVision™ (Bioptics, Tucson, AZ, USA), CMOS technology, photodiode array, flat panel, tungsten source, focus 0.05, resolution 50 µm pixel pitch, 12 lp/mm; 3. the Trident™ specimen radiography system (SRS) (Hologic, Bedford, MA, USA), amorphous selenium, tungsten source, focus 0.05, resolution 70 µm pixel pitch, 7.1 lp/mm; 4. tomosynthesis (Siemens, Erlangen, Germany), amorphous selenium, tungsten source, focus 0.1 mm, resolution 85 µm pixel pitch, 8 lp/mm, angular range 50 degrees, 25 projections, scan time > 20 s, geometry: uniform scanning, reconstruction: filtered back projection. The 600 radiographs were prospectively shown to 3 radiologists. Results: Of the 50 patients with histologically proven breast cancer (BI-RADS™ 6), 39 patients required no further surgical therapy (re-excision) after breast-conserving surgery. A retrospective analysis (n = 11) showed a significant (p < 0.05) increase of sensitivity with the BioVision™, the Trident™ and tomosynthesis compared to the Inspiration™ at a magnification of 1.0 : 2.0 or 1.0 : 1.0 (tomosynthesis) (2.6, 3.3 or 3.6 %), i.e. re-excision would not have been necessary in 2, 3 or 4 patients, respectively, compared to findings obtained with a standard magnification of 1.0 : 1.0. Conclusion: The sensitivity of the BioVision™, the Trident™ and tomosynthesis was significantly (p < 0.05) higher and the rate of re-excisions was reduced compared to FFDM using a conventional detector at a magnification of 2.0 but without zooming.

Full Field Digital Mammography (FFDM) versus CMOS Technology versus Tomosynthesis (DBT) - Which System Increases the Quality of Intraoperative Imaging?

Aim: The aim of this prospective clinical study was to assess whether it would be possible to reduce the rate of re-excisions and improve the quality using CMOS technology or digital breast tomosynthesis (DBT) compared to a conventional FFDM system. Material and Methods: An invasive breast cancer (BI-RADS 5) was diagnosed in 200 patients in the period from 5/2011 to 1/2012. After histological verification, a breast-conserving therapy was performed with intraoperative imaging. Three different imaging systems were used: 1) Inspiration™ (Siemens, Erlangen, Germany), amorphous selenium, tungsten source, focus 0.1 mm, resolution 85 µm pixel pitch, 8 l/mm as the standard; 2) BioVision™ (Bioptics, Tucson, USA), flat panel photodiode array, tungsten source, focus 0.05, resolution 50 µm pixel pitch, 12 l/mm; 3) Tomosynthesis (Siemens, Erlangen, Germany), amorphous selenium, tungsten source, focus 0.1 mm, resolution 85 µm pixel pitch, 8 l/mm, range: 50°, 25 projections, scan time > 20 s, geometry: uniform scanning, reconstruction: filtered back projection. The 600 radiograms were prospectively shown to 3 radiologists. Results: Out of a total of 200 patients with histologically confirmed breast cancer (BI-RADS 6) 156 patients required no further operative therapy (re-excision) after breast-conserving therapy. A retrospective analysis (n = 44) showed an increase in sensitivity with tomosynthesis compared to the BioVision™ (CMOS technology) and the Inspiration™ at a magnification of 1.0 : 1.0 of 8 % (p < 0.05), i.e. re-excision would not have been necessary in 16 patients with tomosynthesis. Conclusions: The sensitivity of tomosynthesis for intraoperative radiography is significantly (p < 0.05) higher compared to both CMOS technology and an FFDM system with a conventional detector. Additional studies using higher magnification, e.g. 2.0 : 1.0, but no zooming will be necessary to evaluate the method further.

Detection of microcalcifications on digital screening mammograms using varying degrees of monitor zooming

OBJECTIVE

The American College of Radiology recommends that mammogram images be viewed at 100% resolution (also called one-to-one or full resolution). We tested the effect of this and three other levels of zooming on the ability of radiologists to identify malignant calcifications on screening mammographic views.

MATERIALS AND METHODS

Seven breast imagers viewed 77 mammographic images, 32 with and 45 without malignant microcalcifications, using four different degrees of monitor zooming. The readers indicated whether they thought a cluster of potentially malignant calcifications was present and where the cluster was located. Tested degrees of zooming included fit screen, a size midway between fit screen and 100%, 100%, and a size slightly larger than 100%.

RESULTS

Readers failed to detect 17 clusters of malignant calcifications with fit-screen images, 12 clusters with midway images, 13 clusters with 100% images, and 11 clusters with slightly larger images. When viewing images without malignant microcalcifications, the readers marked false-positive areas on 25 images using fit-screen images, 43 of the midway images, 40 of the 100% images, and 29 of the slightly larger images.

CONCLUSION

All four tested levels of zooming functioned well. There was a trend for the fit-screen images to function slightly less well than the others with regard to sensitivity, so it may not be prudent to rely on those images without other levels of zooming. The 100% resolution images did not function noticeably better than the others.