Virtual colonoscopy: effect of computer-assisted detection (CAD) on radiographer performance

AIM: To investigate the effect of a virtual colonoscopy (VC) computed-assisted detection (CAD) system on polyp detection by trained radiographers. MATERIALS AND METHODS: Four radiographers trained in VC interpretation and utilization of CAD systems read a total of 62 endoscopically validated VC examinations containing 150 polyps (size range 5-50mm) in four sessions, recording any polyps found and the examination interpretation time, first without and then with the addition of CAD as a "second reader". After a temporal separation of 6 weeks to reduce recall bias, VC examinations were re-read using "concurrent reader" CAD. Interpretation times, polyp detection, and number of false-positives were compared between the different reader paradigms using paired t and paired exact tests. RESULTS: Overall, use of "second reader" CAD significantly improved polyp detection by 12% (p<0.001, CI 6%,17%)) from 48 to 60%. There was no significant improvement using CAD as a concurrent reader (p=0.20; difference of 7%, CI -3%, 16%) and no significant overall difference in recorded false-positives with second reader or concurrent CAD paradigms compared with unassisted reading (p=0.25 and 0.65, respectively). The mean interpretation time was 21.7 min for unassisted reading, 29.6 (p<0.001) min for second reader and 19.1 min (p=0.12) for concurrent reading paradigms. CONCLUSION: CAD, when used as a second reader, can significantly improve radiographer reading performance with only a moderate increase in interpretation times.     

Reproducibility of prompts in computer-aided detection (CAD) of breast cancer

AIM: We evaluated the reproducibility of prompts using the R2 ImageChecker M2000 computer-aided detection (CAD) system. MATERIALS AND METHODS: Forty selected two-view mammograms of women with breast cancer were digitized and analysed using the ImageChecker on 10 separate occasions. The mammograms were chosen to provide both straightforward and subtle signs of malignancy. Data analysed included mammographic abnormality, pathology, and whether the cancer was prompted or given an emphasized prompt. RESULTS: Correct prompts were generated in 86 out of 100 occasions for screen-detected cancers. Reproducibility was less in the other categories of more subtle cancers: 21% for cancers previously missed by CAD, a group that contained more grade 1 and small (<10 mm) tumours. Prompts for calcifications were more reproducible than those for masses (76% versus 53%) and these cancers were more likely to have an emphasized prompt. CONCLUSIONS: Probably the most important cause of variability of prompts is shifts in film position between sequential digitizations. Consequently subtle lesions that are only just above the threshold for display may not be prompted on repeat scanning. However, users of CAD should be aware that even emphasized prompts are not consistently reproducible.     

The role of MRI in assessment of asymmetrical breast densities

This study included 86 women presented with asymmetric breast densities, seen on either routine screening or diagnostic mammogram.     

Performance of a fully automatic lesion detection system for breast DCE-MRI

Purpose:

To describe and test a new fully automatic lesion detection system for breast DCE‐MRI.

Materials and Methods:

Studies were collected from two institutions adopting different DCE‐MRI sequences, one with and the other one without fat‐saturation. The detection pipeline consists of (i) breast segmentation, to identify breast size and location; (ii) registration, to correct for patient movements; (iii) lesion detection, to extract contrast‐enhanced regions using a new normalization technique based on the contrast‐uptake of mammary vessels; (iv) false positive (FP) reduction, to exclude contrast‐enhanced regions other than lesions. Detection rate (number of system‐detected malignant and benign lesions over the total number of lesions) and sensitivity (system‐detected malignant lesions over the total number of malignant lesions) were assessed. The number of FPs was also assessed.

Results:

Forty‐eight studies with 12 benign and 53 malignant lesions were evaluated. Median lesion diameter was 6 mm (range, 5–15 mm) for benign and 26 mm (range, 5–75 mm) for malignant lesions. Detection rate was 58/65 (89%; 95% confidence interval [CI] 79%–95%) and sensitivity was 52/53 (98%; 95% CI 90%–99%). Mammary median FPs per breast was 4 (1st–3rd quartiles 3–7.25).

Conclusion:

The system showed promising results on MR datasets obtained from different scanners producing fat‐sat or non–fat‐sat images with variable temporal and spatial resolution and could potentially be used for early diagnosis and staging of breast cancer to reduce reading time and to improve lesion detection. Further evaluation is needed before it may be used in clinical practice. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

Breast MRI lesion classification: improved performance of human readers with a backpropagation neural network computer-aided diagnosis (CAD) system

PURPOSE: To develop and test a computer-aided diagnosis (CAD) system to improve the performance of radiologists in classifying lesions on breast MRI (BMRI). MATERIALS AND METHODS: A CAD system was developed that uses a semiautomated segmentation method. After segmentation, 42 features based on lesion shape, texture, and enhancement kinetics were computed, and the 13 best features were selected and used as inputs to a backpropagation neural network (BNN). The BNN was trained and tested using the leave-one-out method on 80 BMRI lesions (37 benign, 43 malignant). Lesion histopathology was used as the reference standard. Five human readers classified the 80 lesions first without and then with CAD assistance. The performance of the computer classifier and the human readers was assessed using receiver operating characteristic curves; the performance of the human readers was also evaluated using multireader multicase (MRMC) analysis. RESULTS: The performance of the human readers significantly improved when aided by the CAD system (P < 0.05). MRMC analysis showed that human reader performance with and without CAD system assistance can be generalized to the population of cases (P < 0.001). CONCLUSION: A CAD system based on lesion morphology and enhancement kinetics can improve the performance of human readers in classifying lesions on breast MRI.     

Clinical evaluation of a computer-aided diagnosis (CAD) prototype for the detection of pulmonary embolism

RATIONALE AND OBJECTIVES: To evaluate the performance of a prototype computer-aided diagnosis (CAD) tool using artificial intelligence techniques for the detection of pulmonary embolism (PE) and the possible benefit for general radiologists. MATERIALS AND METHODS: Forty multidetector row computed tomography datasets (16/64- channel scanner) using 100 kVp, 100 mAs effective/slice, and 1-mm axial reformats in a low-frequency reconstruction kernel were evaluated. A total of 80 mL iodinated contrast material was injected at a flow rate of 5 mL/seconds. Primarily, six general radiologists marked any PE using a commercially available lung evaluation software with simultaneous, automatic processing by CAD in the background. An expert panel consisting of two chest radiologists analyzed all PE marks from the readers and CAD, also searching for additional finding primarily missed by both, forming the ground truth. RESULTS: The ground truth consisted of 212 emboli. Of these, 65 (31%) were centrally and 147 (69%) were peripherally located. The readers detected 157/212 emboli (74%) leading to a sensitivity of 97% (63/65) for central and 70% (103/147) for peripheral emboli with 9 false-positive findings. CAD detected 168/212 emboli (79%), reaching a sensitivity of 74% for central (48/65) and 82%(120/147) for peripheral emboli. A total of 154 CAD candidates were considered as false positives, yielding an average of 3.85 false positives/case. CONCLUSIONS: The CAD software showed a sensitivity comparable to that of the general radiologists, but with more false positives. CAD detection of findings incremental to the radiologists suggests benefit when used as a second reader. Future versions of CAD have the potential to further increase clinical benefit by improving sensitivity and reducing false marks.     

Breast cancer detection: Comparison of digital mammography and digital breast tomosynthesis across non-dense and dense breasts

IntroductionBreast density is associated with an increase in breast cancer risk and limits early detection of the disease. This study assesses the diagnostic performance of mammogram readers in digital mammography (DM) and digital breast tomosynthesis (DBT).MethodsEleven breast readers with 1–39 years of experience reading mammograms and 0–4 years of experience reading DBT participated in the study. All readers independently interpreted 60 DM cases (40 normal/20 abnormal) and 35 DBT cases (20 normal/15 abnormal). Sensitivity, specificity, ROC AUC, and diagnostic confidence were calculated and compared between DM and DBT.ResultsDBT significantly improved diagnostic confidence in both dense breasts (p = 0.03) and non-dense breasts (p = 0.003) but not in other diagnostic performance metrics. Specificity was higher in DM for readers with >7 years' experience (p = 0.03) in reading mammography, non-radiologists (p = 0.04), readers who had completed a 3–6 months training fellowship in breast imaging (p = 0.04), and those with ≤2 years’ experience in reading DBT (p = 0.02), particularly in non-dense breasts.ConclusionDiagnostic confidence was higher in DBT when compared to DM. In contrast, other performance metrics appeared to be similar or better with DM and may be influenced by the lack of experience of the reader cohort in reading DBT.Implications for practiceThe benefits of DBT may not be entirely accrued until radiologists attain expertise in DBT interpretation. Specificity of DBT varied according to reader characteristics, and these characteristics may be useful for optimising pairing strategies in independent double reading of DBT as practiced in Australia to reduce false positive diagnostic errors.     

非共面布野方式的调强放射治疗泪腺腺样囊性癌

目的 改进调强放射治疗的照射野布野方法,在提高靶区剂量的同时,尽量减少患侧晶体及其他正常组织的受照射剂量,提高患者长期生存质量.方法 5例患有泪腺腺样囊性癌患者（左侧）,所有患者靶区均包括患侧眶左下壁和眶顶壁.布野方式采取以下三种：（1）常规共面均分9野;（2）非常规共面不均分5野;（3）非常规非共面不均分6野（以下分别简称为9野、5野和6野）.比较以上三种布野方式完成计划的剂量体积直方图（dose volume histogram,DVH）、剂量分布图及物理和生物学参数（最大、最小、平均剂量,适形指数（conformity indexes,CI）和等效均匀剂量（equivalent uniform dose,EUD）.结果 6野计划靶体积（planning target volume,PTV）的D98%、V95%分别比9野和5野增大1.3%、0.6%和11.4%、3.5%,D2%比5野小1%,CI及EUD无明显差别.对于危及器官（organ at risk,OAR）,6野除了脑干的Dmin略差于5野以外,其余均优于9野和5野.结论 从PTV和OARs所受剂量比对情况来看,非常规不均分6野明显具有剂量学优势,要优于其他两种方法.     

18F—FDGPET—CT诊断乳腺癌骨转移的临床应用

目的分析18F—FDGPET—CT对乳腺癌骨转移的诊断价值。方法对107例乳腺癌患者静脉注射18F—FDG行全身PET—CT显像。结果107例中发现骨转移22例,阳性率20．6％。其中无骨痛患者发生骨转移4例,单发转移9例,多发转移13例。发现骨转移灶的部位依次为胸廓（61处）、骨盆（41处）、脊柱（39处）、四肢（8处）及头颅（4处）。随乳腺癌术后回访年限的增加,骨转移阳性率增加。结论18F—FDGPET—CT可早期诊断乳腺癌骨转移,对于病情评价及制定治疗方案有重要的指导意义。     

Computer-aided detection (CAD) in screening mammography: sensitivity of commercial CAD systems for detecting architectural distortion

OBJECTIVE: Computer-aided detection (CAD) algorithms have successfully revealed breast masses and microcalcifications on screening mammography. The purpose of our study was to evaluate the sensitivity of commercially available CAD systems for revealing architectural distortion, the third most common appearance of breast cancer. MATERIALS AND METHODS: Two commercially available CAD systems were used to evaluate screening mammograms obtained in 43 patients with 45 mammographically detected regions of architectural distortion. For each CAD system, we determined the sensitivity for revealing architectural distortion on at least one image of the two-view mammographic examination (case sensitivity) and for each individual mammogram (image sensitivity). Surgical biopsy results were available for each case of architectural distortion. RESULTS: Architectural distortion was deemed present and actionable by a panel of expert breast imagers in 80 views of the 45 cases. One CAD system detected distortion in 22 of 45 cases of distortion (case sensitivity, 49%) and in 30 of 80 mammograms (image sensitivity, 38%); it displayed 0.7 false-positive marks per image. Another CAD system identified distortion in 15 of 45 cases (case sensitivity, 33%) and 17 of 80 mammograms (image sensitivity, 21%); it displayed 1.27 false-positive marks per image. Sensitivity for malignancy-caused distortion was similar to or lower than sensitivity for all causes of distortion. CONCLUSION: Fewer than one half of the cases of architectural distortion were detected by the two most widely available CAD systems used for interpretations of screening mammograms. Considerable improvement in the sensitivity of CAD systems is needed for detecting this type of lesion. Practicing breast imagers who use CAD systems should remain vigilant for architectural distortion.     

Imaging findings in mucinous breast carcinoma and correlating factors

Objective

To investigate the factors influencing mammographic and sonographic features of mucinous breast carcinoma.

Materials and methods

Forty-six patients diagnosed as mucinous breast carcinoma between March 2005 and April 2009 were studied. Mammographies of all patients and sonographies of 41 patients were analyzed retrospectively. Microscopic slides were re-evaluated by a pathologist in order to estimate the volume of extracellular mucus which was classified as: (+), less than 50% of mucus; (++), 50–80% of mucus; and (+++), more than 80% of mucus.

Results

Thirty-one (61.3%) cases of pure mucinous type and 2 (33.3%) of mixed mucinous carcinoma presented as masses had well-defined margins on mammography. No correlation was found between margin characteristics and histological type as well as extracellular mucus rates. Denser breasts and young age group had significantly higher ratios of tumors presented with ill-defined masses than its counterpart. Sonographically, 100% lesions showed a hypoechoic lesion, 76.5% lesions in pure type and 71.4% lesions in mixed type showed a heterogeneous internal echo. No correlation was found between sonographic findings and histological type as well as extracellular mucus rates. Lesions with >40 positivity PCNA had higher ratio presented as ill-defined margins than those of ≤40% positivity PCNA.

Conclusions

The most common appearance of mucinous breast carcinoma is a mass on mammography and a hypoechoic lesion with heterogeneous internal echo on sonography. Mammographic margins and sonographic findings have no relation with histological type and extracellular mucus rate. Mammographic margin features are correlated with breast density and age and PCNA.     

Microcalcification detection with and without CAD system (LIBCAD): A comparative study

The objective of this research is to assess the performance of the LIBCAD as a recent prototype CAD in microcalcification detection, and compare it to the readings of an experienced radiologist.     

乳癌哨兵淋巴结检测临床应用

目的：探讨乳癌哨兵淋巴结活检预测腋窝淋巴结转移状态的可靠性.方法：本组为2000年11月至2004年2月我院收治的140例乳癌患者.术中应用国产亚甲蓝注射液4～6 ml肿瘤上、外、下半圆形皮下连续注射,134例行乳癌改良根治术或患侧乳腺区段切除加腋窝淋巴结清扫术.术后解剖蓝染淋巴管,沿着色淋巴管找到蓝染的哨兵淋巴结.哨兵淋巴结及腋窝淋巴结常规行石蜡病理切片检查.5例行乳腺区段切除加哨兵淋巴结活检,1例行全乳切除加哨兵淋巴结活检（冰冻、石蜡病理检查SLN转移阴性）,未行全腋窝淋巴结清扫.结果：140例患者中136例检出哨兵淋巴结,检出率97.14%,灵敏度 88.71%,准确率94.31%,阴性预测值89.71%,假阴性率11.29%,仅哨兵淋巴结阳性7例.结论：应用亚甲蓝注射液淋巴结着色方法行乳癌哨兵淋巴结活检可以准确地预测腋窝淋巴结转移状态.     

Image-guided core breast biopsy of ductal carcinoma in situ presenting as a non-calcified abnormality

Objective: Ductal carcinoma in situ (DCIS) typically presents as calcifications which are detected mammographically. Our aim was to evaluate the less common presentations of ductal carcinoma in situ diagnosed by image-guided core biopsy and correlate with histopathologic diagnoses. Methods and Material: Imaging and histopathologic findings were retrospectively reviewed in 11 patients with ductal carcinoma in situ diagnosed at core biopsy that presented as noncalcified radiographic abnormalities. Results: Mammography showed non-calcified, circumscribed nodules, ill-defined nodules and architectural distortion. In two patients, no mammographic abnormality was detected. Sonography showed circumscribed, round or oval, solid masses; irregular, heterogeneous masses; and a tubular structure. Histopathologic diagnoses included multiple architectural subtypes and ranged from low to high nuclear grade. Conclusion: Although image-guided core biopsy diagnosis of ductal carcinoma is typically made when sampling calcifications, DCIS can be diagnosed following biopsy of non-calcified masses or distortion. There is no correlation between histopathologic subtype and radiologic appearance.     

Advanced imaging findings and computer-assisted surgery of suspected synovial chondromatosis in the temporomandibular joint

Synovial chondromatosis of the joint occurs mainly in teenagers and young adults. Only 3% of these neoplasms are located in the head and neck region. Synovial chondromatosis of the temporomandibular joint is therefore a very rare disorder. Therefore, developing a working, histological confirmation is required for differential diagnosis. In this case series, the outcome of histological investigation and imaging techniques are compared. Based on clinical symptoms, five cases of suspected synovial chondromatosis of the temporomandibular joint are presented. In each of the subjects, the diagnosis was confirmed by histology. Specific imaging features for each case are described. The tomography images were compared with the histological findings. All patients demonstrated preauricular swelling, dental midline deviation, and limited mouth opening. Computer-assisted surgery was performed. Histology disclosed synovial chondromatosis of the temporomandibular joint in four cases. The other case was found to be a developmental disorder of the tympanic bone. The diagnosis of synovial chondromatosis of the temporomandibular joint can only be based on histology. Clinical symptoms are too general and the available imaging techniques only show nonspecific tumorous destruction, infiltration, and/or residual calcified bodies, they are only for advanced cases. A rare developmental disorder of the tympanic bone--persistence of foramen of Huschke--has to be differentiated.     

Effects of incorrect computer-aided detection (CAD) output on human decision-making in mammography

RATIONALE AND OBJECTIVES: To investigate the effects of incorrect computer output on the reliability of the decisions of human users. This work followed an independent UK clinical trial that evaluated the impact of computer-aided detection(CAD) in breast screening. The aim was to use data from this trial to feed into probabilistic models (similar to those used in "reliability engineering") which would detect and assess possible ways of improving the human-CAD interaction. Some analyses required extra data; therefore, two supplementary studies were conducted. Study 1 was designed to elucidate the effects of computer failure on human performance. Study 2 was conducted to clarify unexpected findings from Study 1. MATERIALS AND METHODS: In Study 1, 20 film readers viewed 60 sets of mammograms (30 of which contained cancer) and provided "recall/no recall" decisions for each case. Computer output for each case was available to the participants. The test set was designed to contain an unusually large proportion (50%) of cancers for which CAD had generated incorrect output. In Study 2, 19 different readers viewed the same set of cases in similar conditions except that computer output was not available. RESULTS: The average sensitivity of readers in Study 1 (with CAD) was significantly lower than the average sensitivity of read-ers in Study 2 (without CAD). The difference was most marked for cancers for which CAD failed to provide correct prompting. CONCLUSION: Possible automation bias effects in CAD use deserve further study because they may degrade human decision-making for some categories of cases under certain conditions. This possibility should be taken into account in the assessment and design of CAD tools.