Diagnostic accuracy of mammography readers and their memory performance have no correlation with each other

INTRODUCTION

The study aims to determine if any association exists between visual memory performance and diagnostic accuracy performance in a group of radiologist mammogram readers.

MATERIALS AND METHODS

One hundred proven mammograms (23 with cancers) were grouped into 5 sets of 20 cases, with sets being of equal difficulty. Pairs of sets were presented in 5 reads (40 cases per read, order random) to a panel of 8 radiologist readers (either present or past screening readers, with experience range from <1 year to >20 years). The readers were asked to either 'clear' or 'call back' cases depending on need for further workup, and at post-baseline reads to indicate whether each case was 'new' or 'old' (i.e. remembered from prior read). Two sets were presented only at baseline (40 cases per reader), and were used to calculate the reader's false recollection rate. Three sets were repeated post-baseline once or twice (100 cases per reader). Reading conditions were standardised.

RESULTS

Memory performance differed markedly between readers. The number of correctly remembered cases (of 100 'old' cases) had a median of 10.5 and range of 0-58. The observed number of false recollections (of 40 'totally new' cases) had a median of 2 and range of 0-17. Diagnostic performance measures were mean (range): sensitivity 0.68 (0.54-0.81); specificity 0.82 (0.74-0.91); positive predictive value (PPV) 0.55 (0.50-0.65); negative predictive value (NPV) 0.89 (0.86-0.93) and accuracy 0.78 (0.76-0.83). Confidence intervals (CIs; 95%) for each reader overlapped for all the diagnostic parameters, indicating a lack of statistically significant difference between the readers at the 5% level. The most sensitive and the most specific reader showed a trend away from each other on sensitivity, specificity, NPV and PPV; their accuracies were 0.76 and 0.82, respectively, and their accuracy 95% CIs overlapped considerably. Correlation analysis by reader showed no association between observed memory performance and any of the diagnostic accuracy measures in our group of readers. In particular, there was no correlation between diagnostic accuracy and memory performance.

CONCLUSION

There was no association between visual memory performance and diagnostic accuracy as a screening mammographer in our group of eight representative readers. Whether a radiologist has a good or a bad visual memory for cases, and in particular mammograms, should not impact on his or her performance as a radiologist and mammogram reader.

Invasive breast cancers detected by screening mammography: a detailed comparison of computer-aided detection-assisted single reading and double reading

To compare double reading plus arbitration for discordance, (currently best practice, (BP)) with computer-aided-detection (CAD)-assisted single reading (CAD-R) for detection of invasive cancers detected within BreastScreen Australia. Secondarily, to examine characteristics of cancers detected/rejected using each method. Mammograms of 157 randomly selected double-read invasive cancers were mixed 1:9 with normal cancers (total 1569), all detected in a BreastScreen service. Cancers were detected by two readers or one reader (C2 and C1 cancers, ratio 70:30%) in the program. The 1569 film-screen mammograms were read by two radiologists (reader A (RA) and reader B(RB)), with findings recorded before and after CAD. Discordant findings with BP were resolved by arbitration. We compared CAD-assisted reading (CAD-RA, CAD-RB) with BP, and CAD and arbitration contribution to findings. We correlated cancer size, sensitivity and mammographic density with detection methods. BP sensitivity 90.4% compared with CAD-RA sensitivity 86.6% (P = 0.12) and CAD-RB 94.3% (P = 0.14). CAD-RB specificity was less than BP (P = 0.01). CAD sensitivity was 93%, but readers rejected most positive CAD prompts. After CAD, reader's sensitivity increased 1.9% and specificity dropped 0.2% and 0.8%. Arbitration decreased specificity 4.7%. Receiving operator curves analysis demonstrated BP accuracy better than CAD-RA, borderline significance (P = 0.07), but not CAD-RB. Secondarily, cancer size was similar for BP and CAD-R. Cancers recalled after arbitration (P = 0.01) and CAD-R (P = 0.10) were smaller. No difference in cancer size or sensitivity between reading methods was found with increasing breast density. CAD-R and BP sensitivity and cancer detection size were not significantly different. CAD-R specificity was significantly lower for one reader.

A systematic review of the effectiveness of magnetic resonance imaging (MRI) as an addition to mammography and ultrasound in screening young women at high risk of breast cancer

Breast magnetic resonance imaging (MRI) has been proposed as an additional screening test for young women at high risk of breast cancer in whom mammography alone has poor sensitivity. We conducted a systematic review to assess the effectiveness of adding MRI to mammography with or without breast ultrasound and clinical breast examination (CBE) in screening this population. We found consistent evidence in 5 studies that adding MRI provides a highly sensitive screening strategy (sensitivity range: 93-100%) compared to mammography alone (25-59%) or mammography plus ultrasound+/-CBE (49-67%). Meta-analysis of the three studies that compared MRI plus mammography versus mammography alone showed the sensitivity of MRI plus mammography as 94% (95%CI 86-98%) and the incremental sensitivity of MRI as 58% (95%CI 47-70%). Incremental sensitivity of MRI was lower when added to mammography plus ultrasound (44%, 95%CI 27-61%) or to the combination of mammography, ultrasound plus CBE (31-33%). Estimates of screening specificity with MRI were less consistent but suggested a 3-5-fold higher risk of patient recall for investigation of false positive results. No studies assessed as to whether adding MRI reduces patient mortality, interval or advanced breast cancer rates, and we did not find strong evidence that MRI leads to the detection of earlier stage disease. Conclusions about the effectiveness of MRI therefore depend on assumptions about the benefits of early detection from trials of mammographic screening in older average risk populations. The extent to which high risk younger women receive the same benefits from early detection and treatment of MRI-detected cancers has not yet been established.

The sensitivity, specificity, and positive predictive value of screening mammography and symptomatic status

OBJECTIVE

To examine whether the accuracy of screening mammography varies according to symptomatic status reported at the time of screening.

SETTING

Victoria, Australia, where free biennial screening is provided to women aged 40 and older.

METHODS

We examined the sensitivity, specificity, and the positive predictive value of screening mammography by symptom status in 106,826 women from Victoria, who attended for first round mammography in 1994 and who did not have a personal history of breast cancer. Symptomatic status was divided into the following categories: asymptomatic; significant symptoms, if the woman reported a breast lump and/or blood stained or watery nipple discharge; and other symptoms, if reported. Unconditional logistic regression modelling was used to adjust for age, use of hormone replacement therapy (HRT), and family history.

RESULTS

Sensitivity was lower for women with other symptoms (60.0%) than asymptomatic women (75.6%), or women with significant symptoms (80.8%). Specificity was lower for women with significant symptoms (73.7%) than asymptomatic women (94.9%), or women with other symptoms (95.4%). Among women who had invasive cancer detected during screening interval, women with other symptoms were more likely to get a false negative result (odds ratio 1.79, 95% confidence interval 1.03 to 3.04) than asymptomatic women, after adjusting for age, use of HRT, and family history.

CONCLUSION

The lower sensitivity in women with other symptoms requires further investigation. Possible explanations include increased breast density and poor image quality. The high sensitivity in women with significant symptoms is probably due to more cautious radiological practice, which has also resulted in low specificity in this group.

Invasive lobular carcinoma: sonographic features of cancers detected in a BreastScreen Program

Sixty-two screen-detected invasive lobular carcinomas (ILC) were studied for sonographic, mammographic, clinical and histological findings. Ultrasound (US) features were compared with 60 invasive duct cancers (IDC). Size and axillary lymph node status in ILC were compared with all other cancers detected. In 41 ILC examined with US, 36 were found as masses (87.8% sensitivity; 95% CI 77.8-97.8%). Some US features of ILC and IDC differed: ILC were 9.94 times more likely to be hyperechoic (odds ratio, OR, 9.94; 95% CI 3.28-31.74) and 77% less likely to be taller than wide (OR 0.23; 95% CI 0.18-0.62). Thirty-three ILC showed typical malignant features of spiculate margins and acoustic shadowing. invasive lobular carcinomas had a greater mean diameter (20.4 mm; n = 60) than other invasive cancers (14.4 mm; n = 322) (P < 0.001). Ultrasound-guided needle biopsy was the method of diagnosis in 26 of 41 impalpable ILC (63%). Ultrasound has high sensitivity in characterizing screen-detected ILC, which may have atypical sonographic features including hyperechogenicity and a wider than tall shape. Ultrasound was an important contributor to diagnosis.

Axillary dissection and ductal carcinoma in situ of the breast: a change in practice

BACKGROUND

Axillary dissection may be associated with significant morbidity and, while it is necessary in the treatment of invasive breast cancer, is not indicated for the treatment of pure ductal carcinoma in situ (DCIS), although it is being performed in a significant number of cases. The present study examined the incidence of elective axillary dissection in the treatment of DCIS cases detected in a mammographic screening programme over a 4-year period, and whether surgeons have changed their practice in this respect.

METHODS

BreastScreen Victoria records were examined retrospectively for the period from January 1995 to December 1998 to identify patients treated for DCIS. The incidence and indications for axillary surgery were investigated.

RESULTS

There were 579 cases of DCIS and 93 (16%) had some form of axillary surgery, which was thought to be inappropriate in 57 (10%), the latter being performed by 21 city surgeons and 20 rural surgeons. Before surgery, 36 (63%) cases were diagnosed by core biopsy or excision, and 21 (37%) had imaging and cytology alone for diagnosis. The rate of unnecessary axillary dissections dropped steadily from 14% in 1995 to 4% in 1998, a significant reduction (P = 0.01).

CONCLUSION

The incidence of axillary dissection for DCIS has dropped significantly over the last 4 years in Victoria, possibly due to increased awareness through education and guidelines. Surgeons are now more aware that in situ lesions do not need axillary dissection, and that axillary dissection should not be performed for breast cancer unless invasion has been proved histologically.

Epidermal cyst of the breast: detection in a screening programme

Two cases of epidermal cyst of the breast, a rare benign condition, were detected during a 3-year period in a mammographic screening programme, from 57,954 screening examinations. It is not uncommon for epidermal cysts to be initially misdiagnosed. The mammographic, ultrasound and histological features are presented. It is recommended that these lesions be resected because they possibly have malignant potential.

Characteristics and treatment of breast cancers 10 mm or less detected by a mammographic screening programme

BACKGROUND

Small invasive breast cancers up to 10 mm in size have an excellent prognosis and are being detected in increasing numbers by mammographic screening, yet optimal treatment remains controversial.

METHODS

A review was made of pathology and treatment data relating to 100 consecutive invasive breast cancers up to 10 mm in size detected among 52,126 women who were screened over a 32-month period.

RESULTS

The most common radiological finding was a stellate lesion (44%). Thirty-three cases had an extensive in situ component in addition to the invasive tumour, and included among these were seven ductal carcinoma in situ (DCIS) cases with microinvasion. Of 79 patients who had axillary dissections, seven (9%) were node-positive. Tumours < or = 5 mm were as likely to be node-positive (11%) as those 6-10 mm in size (8%). Positive nodes were found only in patients with more than five nodes excised. Breast conservation surgery was performed in 84% of patients treated by surgeons associated with the programme, and 63% of patients were treated by other surgeons (P = 0.054, exact test). Breast radiation after breast conservation surgery was used in 44% of the cases, but was almost twice as likely to be used if the tumours were > 5 mm (51%) than if the tumours were < or = 5 mm (29%). Adjuvant tamoxifen was given to 61% of the cases.

CONCLUSIONS

We found that small invasive breast cancers are commonly treated by breast conservation, which usually includes axillary dissection. Even the smallest may be node-positive, and there is uncertainty about the place of adjuvant radiation therapy and tamoxifen.

Risk factors and preventive strategies for breast cancer

Several risk factors for breast cancer are readily identifiable, but most are not preventable. Hence the importance of screening, as early diagnosis and treatment offer the best hope of saving lives.