INTRODUCTION
Switching from screen-film mammography to digital mammography entails a lot more for the
reporting radiologists, than switching from a light box to a computer monitor. Soft-copy viewing of
the digitally processed image demands different skills and thus knowledge from the radiologist.
The image processing option on digital mammography units is vendor dependant and the optimal
processing options have not yet been established.
The main aim of this study was to develop and evaluate a soft-copy viewing protocol for
mammography through participative learning to improve radiological reporting.
METHODS
A phantom-based method was used to identify a smaller set of processing options to be evaluated
for image quality assessment on clinical images. Three (3) radiologists were trained in the new
modality with specific emphasis on how to address the challenges of soft-copy viewing. The
viewing protocol was developed through participative learning. The radiologists scored the image
quality on thirty six (36) medio-lateral oblique images processed with four (4) different image
processing options (MUSICA2, MUSICA2 Invert, Unprocessed, and Unprocessed Invert). An
image quality score was calculated to find the best processing option for the anatomical structures
overall, anatomical structures individually, masses, calcifications, noise, and the early detection of
breast cancer. A viewing protocol was recommended based on the findings. The effect of the
viewing protocol was assessed by comparing diagnostic accuracy of the radiologists before and
after the viewing protocol. They reported on eighty (80) mammograms using the breast imaging
and reporting data system (BI-RADS) of the American College of Radiology. Sensitivity, specificity, positive predictive value (PPV) and BI-RADS category 3 were calculated and
compared.
RESULTS
The phantom-based method found Unprocessed Invert, MUSICA2, MUSICA2 Invert, and
Unprocessed to provide the best image quality. These processing options were therefore
identified for image quality assessment on clinical images. For the anatomical structures overall,
MUSICA2 provided significantly superior image quality compared to Unprocessed (p<0.0001) and
Unprocessed Invert (p<0.0001). MUSICA2 Invert also provided significantly superior image quality
compared to Unprocessed (p<0.0001) and Unprocessed Invert (p=0.0003) for that. The only
significant difference between MUSICA2 and MUSICA2 Invert was found for skin outline for which
MUSICA2 Invert showed superiority (p=0.0563). The image quality of vessels in dense
parenchyma was found be significantly inferior to that of all other anatomical structures with all
processing options, even with the processed images (p<0.0001). For calcifications MUSICA2
provided significantly superior image quality compared to Unprocessed and its Invert (p=0.0066
and p=0.0001 respectively). However, no significant difference was found between any of the
processing options for masses (p>0.05). Noise was significantly less visible for Unprocessed
compared to MUSICA2 (p = 0.016) although it was still acceptable to all three radiologists in 97.2%
of cases with MUSICA2. For the early detection of breast cancer, MUSICA2 was found to be
significantly superior to Unprocessed (p=0.0003) and Unprocessed Invert (p=0.0005). The
recommended default processing option for the viewing protocol was MUSICA2 Invert. After the
development of the viewing protocol, sensitivity increased for two of the radiologists [from 90% to
95% (p=0.6752)], and from 90% to 97.5% (p =0.3589) respectively]; specificity increased for two of
the radiologists [from 61.5% to 72.5% (p=0.2999), and from 70% to 85% (p=0.1082) respectively];
PPV increased for all three radiologists [from 71.7% to 77.6% (p=0.6198), from 75% to 86.4%
(p=0.1699), and from 83.7% to 84.8% (p=0.8907) respectively]. The percentage BI-RADS category 3 cases decreased for two of the radiologists [from 15% to 12.5% (p=0.6461) and from
28.8% to 22.5% (p=0.2810) respectively].
CONCLUSIONS
Although not significant, the study found improvement in diagnostic accuracy after the
development of the viewing protocol. Training of radiologists in the new modality and knowledge
of the effect of image processing on image quality is regarded as important. The development of
the viewing protocol through participative learning of the radiologist provided evidence to the
radiologists that they could confidently use the proposed viewing protocol in clinical practice.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-09162013-125601 |
| Date | 16 September 2013 |
| Creators | Meyer, Carin |
| Contributors | Prof CP Herbst, Prof WID Rae |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-09162013-125601/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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