Patient Preferences of Breast Radiologists' Attire and Appearance

RATIONALE AND OBJECTIVES

To assess patient preferences for breast radiologists' attire and appearance.

MATERIALS AND METHODS

A multi-institutional anonymous, voluntary 19-question survey was administered to patients undergoing screening and diagnostic mammography examinations over a 5-week period. Using a 5-point Likert scale, respondents were asked about their preferences for gender-neutral attire (white coat), male-presenting attire (scrubs, dress shirt with tie, or dress shirt without tie), and female-presenting attire (scrubs, dress, blouse with pants, and blouse with skirt). Patient responses were compared to demographic data using bivariable analysis and multivariable regression.

RESULTS

Response rate was 84.7% (957/1130). Mean respondent age was 57.2 years±11.9. Most respondents agreed/strongly agreed that the breast radiologist's appearance mattered (52.5%, 502/956) followed by being indifferent (28.1%, 269/956). Respondents with greater education levels felt less strongly (p=0.001) about the radiologist's appearance: 63.3% (70/110) less than college cared about appearance compared to 53.5% (266/497) college/vocational and 47.4% (165/348) graduate. Most respondents felt indifferent about a breast radiologist wearing a white coat (68.9%, 657/954) or about male-presenting breast radiologists wearing a tie (77.1%, 734/952) without significant demographic differences. Almost all respondents either prefer/strongly prefer (60.1%, 572/951) or were indifferent (39.6%, 377/951) to all breast radiologists wearing scrubs when performing procedures. While respondents approved of all attire choices overall, most respondents preferred scrubs for both male- and female-presenting breast radiologists (64.0%, 612/957 and 64.9%, 621/957, respectively).

CONCLUSION

A variety of breast radiologists' attire can be worn while maintaining provider professionalism and without compromising patient expectations.

Impact of Interruptions During Screening Mammography on Physician Well-Being and Patient Care

OBJECTIVE

To assess the impact of interruptions on radiologists' efficiency, accuracy, and job satisfaction in interpreting screening mammograms.

METHODS

This institutional review board-approved retrospective reader study recruited nine breast radiologists from a single academic institution [name withheld] to interpret 150 screening mammograms performed between December 1, 2008, and December 31, 2015 under two different reading conditions, as follows: (1) uninterrupted batch reading and (2) interrupted reading. The 150 cases consisted of 125 normal mammograms and 25 mammograms with subtle breast cancers. Cases were divided into two groups of 75 cases each (cohort 1 and cohort 2), with a comparable distribution of cancer cases. Four rounds of 75 cases each were conducted with a 6-week washout period between rounds 2 and 3. After completing each interpretation session, readers completed a seven-question survey, assessing perceptions of mental and physical effort, level of frustration, and performance satisfaction. Clinical performance metrics (reading time, recall rate, sensitivity, specificity, accuracy, and positive predictive value 1) were calculated.

RESULTS

Recall rates were significantly (P = .04) higher during interrupted reading sessions (35.4%) than they were during uninterrupted batch reading sessions (31.4%). Accuracy was significantly (P = .049) worse in the interrupted reading sessions (69.5%), compared with uninterrupted sessions (73.6%). Differences in overall image interpretation times were not statistically significant (P = .065). Compared with uninterrupted batch reading sessions, readers during interrupted sessions reported feeling busier (P < .001), encountered higher levels of cognitive demand (P = .005), experienced elevated levels of physical fatigue (P = .004), and expressed lower levels of satisfaction with their performance (P = .041).

CONCLUSION

Interruptions during interpretation of screening mammography have deleterious effects on physician performance and their sense of well-being.

Racial Disparities in Breast Imaging Wait Times Before and After the Implementation of a Same-Day Biopsy Program

OBJECTIVE

To examine time from screening to diagnostic workup, biopsy, and surgery for non-Hispanic White (NHW) and Black women following implementation of a same-day biopsy program.

METHODS

All NHW and Black women with BI-RADS category 0 screening mammogram at Duke University Hospital were identified between August 1, 2020, and August 1, 2021. Patient characteristics were recorded. Time between screening mammogram, diagnostic workup, breast biopsy, surgical consultation, and surgery were recorded. Comparisons were made between NHW and Black women using a multivariable regression model. Diagnostic imaging to biopsy time interval was compared to historical averages before same-day biopsy implementation.

RESULTS

There were 2156 women: 69.9% NHW (1508/2156) and 30.1% Black (648/2156). Mean ± standard deviation time from screening to diagnostic imaging overall was 13.5 ± 32.5 days but longer for Black (18.0 ± 48.3 days) than for NHW women (11.5 ± 22.2 days) (P < 0.001). The mean time from diagnostic mammogram to biopsy was 5.9 ± 18.9 days, longer for Black (9.0 ± 27.9 days) than for NHW women (4.4 ± 11.8 days) (P = 0.017). The same-day biopsy program shortened the time from diagnostic imaging to biopsy overall (12.5 ± 12.4 days vs 5.9 ± 18.9 days; P < 0.001), with a significant reduction for NHW women (12.4 ± 11.7 days vs 4.4 ± 11.8 days) (P < 0.001) but not Black women (11.5 ± 9.9 days vs 9.0 ± 27.9 days) (P = 0.527).

CONCLUSION

Disparities exist along the breast imaging pathway. A same-day biopsy program benefited NHW women more than Black women.

Ethanol Sclerotherapy for Postoperative Seroma of the Breast and Axilla

OBJECTIVE

Evaluate the effectiveness of alcohol sclerotherapy in postoperative breast and axillary seromas.

METHODS

This was an IRB-approved retrospective review of consecutive patients from 2017 to 2021. The procedure involves aspiration of seroma fluid, injection of ethanol for 15 to 30 minutes, and then aspiration of the injected ethanol. Following review of the medical record, patient and procedure data were recorded. Success was defined as no recurrence of seroma. Statistical analysis was performed using a chi-square or t-test, as appropriate.

RESULTS

Twenty seromas were treated in 19 patients (mean age, 63 years; range, 49-79) following mastectomy (9/20, 45%), lumpectomy (25%, 5/20), axillary nodal dissection (5/20, 25%), or chest wall surgery (1/20, 5%). The mean seroma volume was 146 ± 165 mL. There was a mean of 1.4 prior aspiration attempts (range, 0-3). Mean injected ethanol volume was 39 mL (range, 8-60 mL) for a mean of 26 ± 5 minutes. Seromas recurred in 85% (17/20) of cases, and repeat aspiration was performed in 35% (6/17). The mean recurrence time was 34 ± 29 days. The recurrent seromas were 31% smaller (mean, 80 ± 48 mL). Only a smaller pre-ablation seroma was associated with successful ablation (P < 0.01), as the mean pre-ablation volume was 36 ± 24 mL for successful ablations and 119 ± 56 mL for unsuccessful ablations. There were no post-procedural complications.

CONCLUSION

Single-treatment ethanol sclerotherapy is typically unsuccessful in ablating breast and axillary seromas. Only a smaller pre-ablation seroma size was associated with successful ablation.

Detection efficiency calibration for an array of fourteen HPGe detectors

The CUP array of germanium (CAGe) is an array of fourteen high-purity germanium (HPGe) detectors. The detection efficiency of full-energy-peak emitted from the various samples assayed on the CAGe was calculated using the Monte Carlo simulation toolkit GEANT4. If the dead layer on the surface of the crystal is treated in the simulation as a continuous part of the active crystal, then the detection efficiency will be overestimated. Thus, the detection efficiency of the CAGe was adjusted using multi-nuclide source data and Monte Carlo simulations. The gamma spectra of the known activity source were obtained for each HPGe detector of the CAGe. The detection efficiency measured by the multi-source data was smaller than that of simulation data if the simulation treated the whole volume of germanium crystals as active for gamma detection. By optimizing the dead layers' thicknesses in the simulation, the detection efficiency calculated by the simulation could be matched to that of multi-source data.

Mixed-Methods Study to Predict Upstaging of DCIS to Invasive Disease on Mammography

BACKGROUND. The incidence of ductal carcinoma in situ (DCIS) has steadily increased, as have concerns regarding overtreatment. Active surveillance is a novel treatment strategy that avoids surgical excision, but identifying patients with occult invasive disease who should be excluded from active surveillance is challenging. Radiologists are not typically expected to predict the upstaging of DCIS to invasive disease, though they might be trained to perform this task. OBJECTIVE. The purpose of this study was to determine whether a mixed-methods two-stage observer study can improve radiologists' ability to predict upstaging of DCIS to invasive disease on mammography. METHODS. All cases of DCIS calcifications that underwent stereotactic biopsy between 2010 and 2015 were identified. Two cohorts were randomly generated, each containing 150 cases (120 pure DCIS cases and 30 DCIS cases upstaged to invasive disease at surgery). Nine breast radiologists reviewed the mammograms in the first cohort in a blinded fashion and scored the probability of upstaging to invasive disease. The radiologists then reviewed the cases and results collectively in a focus group to develop consensus criteria that could improve their ability to predict upstaging. The radiologists reviewed the mammograms from the second cohort in a blinded fashion and again scored the probability of upstaging. Statistical analysis compared the performances between rounds 1 and 2. RESULTS. The mean AUC for reader performance in predicting upstaging in round 1 was 0.623 (range, 0.514-0.684). In the focus group, radiologists agreed that upstaging was better predicted when an associated mass, asymmetry, or architectural distortion was present; when densely packed calcifications extended over a larger area; and when the most suspicious features were focused on rather than the most common features. Additionally, radiologists agreed that BI-RADS descriptors do not adequately characterize risk of invasion, and that microinvasive disease and smaller areas of DCIS will have poor prediction estimates. Reader performance significantly improved in round 2 (mean AUC, 0.765; range, 0.617-0.852; p = .045). CONCLUSION. A mixed-methods two-stage observer study identified factors that helped radiologists significantly improve their ability to predict upstaging of DCIS to invasive disease. CLINICAL IMPACT. Breast radiologists can be trained to better predict upstaging of DCIS to invasive disease, which may facilitate discussions with patients and referring providers.

Predicting Upstaging of DCIS to Invasive Disease: Radiologists's Predictive Performance

RATIONALE AND OBJECTIVES

The purpose of this study is to quantify breast radiologists' performance at predicting occult invasive disease when ductal carcinoma in situ (DCIS) presents as calcifications on mammography and to identify imaging and histopathological features that are associated with radiologists' performance.

MATERIALS AND METHODS

Mammographically detected calcifications that were initially diagnosed as DCIS on core biopsy and underwent definitive surgical excision between 2010 and 2015 were identified. Thirty cases of suspicious calcifications upstaged to invasive ductal carcinoma and 120 cases of DCIS confirmed at the time of definitive surgery were randomly selected. Nuclear grade, estrogen and progesterone receptor status, patient age, calcification long axis length, and breast density were collected. Ten breast radiologists who were blinded to all clinical and pathology data independently reviewed all cases and estimated the likelihood that the DCIS would be upstaged to invasive disease at surgical excision. Subgroup analysis was performed based on nuclear grade, long axis length, breast density and after exclusion of microinvasive disease.

RESULTS

Reader performance to predict upstaging ranged from an area under the receiver operating characteristic curve (AUC) of 0.541-0.684 with a mean AUC of 0.620 (95%CI: 0.489-0.751). Performances improved for lesions smaller than 2 cm (AUC: 0.676 vs 0.500; p = 0.002). The exclusion of microinvasive cases also improved performance (AUC: 0.651 vs 0.620; p = 0.005). There was no difference in performance based on breast density (p = 0.850) or nuclear grade (p = 0.270) CONCLUSION: Radiologists were able to predict invasive disease better than chance, particularly for smaller DCIS lesions (<2 cm) and after the exclusion of microinvasive disease.

Machine learning-based prediction of future breast cancer using algorithmically measured background parenchymal enhancement on high-risk screening MRI

BACKGROUND

Preliminary work has demonstrated that background parenchymal enhancement (BPE) assessed by radiologists is predictive of future breast cancer in women undergoing high-risk screening MRI. Algorithmically assessed measures of BPE offer a more precise and reproducible means of measuring BPE than human readers and thus might improve the predictive performance of future cancer development.

PURPOSE

To determine if algorithmically extracted imaging features of BPE on screening breast MRI in high-risk women are associated with subsequent development of cancer.

STUDY TYPE

Case-control study.

POPULATION

In all, 133 women at high risk for developing breast cancer; 46 of these patients developed breast cancer subsequently over a follow-up period of 2 years.

FIELD STRENGTH/SEQUENCE

5 T or 3.0 T T₁ -weighted precontrast fat-saturated and nonfat-saturated sequences and postcontrast nonfat-saturated sequences.

ASSESSMENT

Automatic features of BPE were extracted with a computer algorithm. Subjective BPE scores from five breast radiologists (blinded to clinical outcomes) were also available.

STATISTICAL TESTS

Leave-one-out crossvalidation for a multivariate logistic regression model developed using the automatic features and receiver operating characteristic (ROC) analysis were performed to calculate the area under the curve (AUC). Comparison of automatic features and subjective features was performed using a generalized regression model and the P-value was obtained. Odds ratios for automatic and subjective features were compared.

RESULTS

The multivariate model discriminated patients who developed cancer from the patients who did not, with an AUC of 0.70 (95% confidence interval: 0.60-0.79, P < 0.001). The imaging features remained independently predictive of subsequent development of cancer (P < 0.003) when compared with the subjective BPE assessment of the readers.

DATA CONCLUSION

Automatically extracted BPE measurements may potentially be used to further stratify risk in patients undergoing high-risk screening MRI.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;50:456-464.

Relationship between Background Parenchymal Enhancement on High-risk Screening MRI and Future Breast Cancer Risk

RATIONALE AND OBJECTIVES

To determine if background parenchymal enhancement (BPE) on screening breast magnetic resonance imaging (MRI) in high-risk women correlates with future cancer.

MATERIALS AND METHODS

All screening breast MRIs (n = 1039) in high-risk women at our institution from August 1, 2004, to July 30, 2013, were identified. Sixty-one patients who subsequently developed breast cancer were matched 1:2 by age and high-risk indication with patients who did not develop breast cancer (n = 122). Five fellowship-trained breast radiologists independently recorded the BPE. The median reader BPE for each case was calculated and compared between the cancer and control cohorts.

RESULTS

Cancer cohort patients were high-risk because of a history of radiation therapy (10%, 6 of 61), high-risk lesion (18%, 11 of 61), or breast cancer (30%, 18 of 61); BRCA mutation (18%, 11 of 61); or family history (25%, 15 of 61). Subsequent malignancies were invasive ductal carcinoma (64%, 39 of 61), ductal carcinoma in situ (30%, 18 of 61) and invasive lobular carcinoma (7%, 4of 61). BPE was significantly higher in the cancer cohort than in the control cohort (P = 0.01). Women with mild, moderate, or marked BPE were 2.5 times more likely to develop breast cancer than women with minimal BPE (odds ratio = 2.5, 95% confidence interval: 1.3-4.8, P = .005). There was fair interreader agreement (κ = 0.39).

CONCLUSIONS

High-risk women with greater than minimal BPE at screening MRI have increased risk of future breast cancer.

Authorship and Impact of Gender-Specific Research in Major Radiology Journals

PURPOSE

The purpose of this study is to quantify the relationship between author gender and publication topic, as well as the impact of gender-related research.

METHODS

We reviewed all original research publications in Radiology, American Journal of Roentgenology, and Academic Radiology from 2011 through 2015. For each article, we recorded the gender of all authors and the last author H-index, years in practice, and academic rank. The total citations and citation rate (citations per year) were calculated for each article. Articles were categorized as gender-neutral, women's health, or men's health.

RESULTS

There were 1,934 publications involving 11,657 authors. Women represented 30% of first, 25% of last, and 28% of all authors. There were 1,596 (83%) gender-neutral, 276 (14%) women's health, and 61 (3%) men's health articles. Women's health articles were associated with a female first (odds ratio [OR] = 5.0, P < .001) and last author (OR = 6.4, P < .001), as well as more female authors (male = 1.4, female = 3.6, P < .001). Men's health articles were associated with a male first (OR = 2.6, P = .004) and last author (OR = 2.2, P = .03). There were significantly more citations for men's (43.5 ± 54.9, P < .001) and women's health (27.6 ± 37.5, P < .008) articles than gender-neutral articles (21.9 ± 28.9). Similarly, the article citation rate was higher for men's (10.6 ± 11.3, P < .001) and women's health (6.8 ± 8.5, P = .004) articles than gender-neutral publications (5.3 ± 7.0).

CONCLUSION

Radiology researchers publish more often on topics related to their own gender. Furthermore, men's and women's health research generates more citations than gender-neutral research.

Bridging the Gap: Identifying Global Trends in Gender Disparity Among the Radiology Physician Workforce

RATIONALE AND OBJECTIVES

Women make up half of American medical school graduates, but remain underrepresented among radiologists. This study sought to determine whether workforce gender disparities exist in other countries, and to identify any country-specific indices associated with increased female representation.

MATERIALS AND METHODS

In this cross-sectional study, 95 professional radiology organizations in 75 countries were contacted via email to provide membership statistics, including proportion of female members, female members aged 35 or under, and women in society leadership positions. Country-specific metrics collected included gross domestic product, Gini index, percent female medical school enrollment, and Gender Development Index for the purposes of univariate multiple regression analysis.

RESULTS

Twenty-nine organizations provided data on 184,888 radiologists, representing 26 countries from Europe (n = 12), North America (n = 2), Central/South America (n = 6), Oceania (n = 2), Asia (n = 3), and Africa (n = 1) for a response rate of 34.7% (26/75). Globally, 33.5% of radiologists are female. Women constitute a higher proportion of younger radiologists, with 48.5% of radiologists aged 35 or under being female. Female representation in radiology is lowest in the United States (27.2%), highest in Thailand (85.0%), and most variable in Europe (mean 40.1%, range 28.8%-68.9%). The proportion of female radiologists was positively associated with a country's Gender Development Index (P = .006), percent female medical student enrollment (P = .001), and Gini index (P = .002), and negatively associated with gross domestic product (P = .03).

CONCLUSIONS

Women are underrepresented in radiology globally, most notably in the United States. Countries with greater representation of women had higher gender equality and percent female medical school enrollment, suggesting these factors may play a role in the gender gap.

Collaboration Metrics Among Female and Male Researchers: A 5-Year Review of Publications in Major Radiology Journals

RATIONALE AND OBJECTIVES

Women are under-represented in radiology, but the implications of this under-representation are poorly understood. Therefore, the purpose of this study was to determine if articles published by women in major radiology journals were more collaborative.

MATERIALS AND METHODS

Following an institutional review board exemption, we reviewed all original research articles in Radiology, in the American Journal of Roentgenology, and in Academic Radiology from 2011 to 2015. For each article, the gender of the first and the last authors and proxy measures of collaboration were recorded, including the total number of authors, female authors, departments, and institutions. Nominal logistic regression analysis was used to test for associations while controlling for confounders.

RESULTS

There were 1934 articles analyzed. Female first and last authors represented 30.2% (585 of 1934) and 24.4% (473 of 1934) of the articles, respectively. A female first author was associated with more female last authors (36% vs 20%, P < .001), total female authors (2.9 vs 1.2, P < .001), and departments (3.3 vs 3.0, P < .001). Similarly, a female last author was associated with more female first authors (44% vs 26%, P = .001), total female authors (3.1 vs 1.2, P < .001), departments (3.5 vs 3.0 P < .001), and institutions (2.3 vs 1.9, P = .006). Each additional female author increased the mean number of institutions by 0.33 and departments by 0.46 on linear regression. First- or last-author gender was not associated with total authors (P = .17).

CONCLUSIONS

Original research articles published with a female first or last author were associated with more departments and institutions, but not with the total number of authors, suggesting that women engage in some metrics of more collaborative research.

Differential Motivations for Pursuing Diagnostic Radiology by Gender: Implications for Residency Recruitment

RATIONALE AND OBJECTIVES

The purpose of this study is to determine how the motivations to pursue a career in radiology differ by gender. In addition, the influence of medical school radiology education will be assessed.

MATERIALS AND METHODS

Radiology applicants to our institution from the 2015-2016 interview season were offered an online survey in February 2016. Respondents scored the influence of 24 aspects of radiology on their decision to pursue radiology. Comparisons were made between male and female respondents. Respondents were also asked the type of medical school radiology education they received and to score the influence this experience had on their decision to pursue radiology.

RESULTS

There were 202 total respondents (202/657) including 47 women and 155 men. Compared to men, the following factors had a more negative impact on women: flexible work hours (P = 0.04), work environment (P = 0.04), lifestyle (P = 0.04), impact on patient care (P = 0.05), high current debt load (P = 0.02), gender distribution of the field (P = 0.04), and use of emerging/advanced technology (P = 0.02). In contrast, women felt more favorably about the opportunities for leadership (P = 0.04) and research (P < 0.01). Dedicated radiology exposure was as follows: 20% (n = 20) none, 48% (n = 96) preclinical exposure, 55% (n = 111) elective rotation, and 18% (n = 37) core rotation. More intensive radiology exposure via a core rotation had a significantly positive impact on the decision to pursue radiology (P < 0.01).

CONCLUSIONS

Male and female radiology applicants are motivated by different aspects of radiology, which may influence residency recruitment practices. In addition, more intensive radiology exposure has a net positive impact on the decision to pursue radiology.

Anxiety prior to breast biopsy: Relationships with length of time from breast biopsy recommendation to biopsy procedure and psychosocial factors

This study investigated how time from breast biopsy recommendation to biopsy procedure affected pre-biopsy anxiety ( N = 140 women), and whether the relationship between wait time and anxiety was affected by psychosocial factors (chronic life stress, traumatic events, social support). Analyses showed a significant interaction between wait time and chronic life stress. Increased time from biopsy recommendation was associated with greater anxiety in women with low levels of life stress. Women with high levels of life stress experienced increased anxiety regardless of wait time. These results suggest that women may benefit from shorter wait times and receiving strategies for managing anxiety.

HMGB1 in the pathogenesis of ultraviolet-induced ocular surface inflammation

High-mobility group box 1 (HMGB1) functions as a transcription-enhancing nuclear protein as well as a crucial cytokine that regulates inflammation. This study demonstrated that secretion of HMGB1 due to ultraviolet (UV) radiation inducing ocular surface inflammation-mediated reactive oxygen species (ROS) production. After treating conjunctival epithelial cells with UV radiation, HMGB1 was translocated from the nucleus to the cytoplasm and then eventually to the extracellular space. HMGB1 played a crucial role in UV-induced conjunctival neutrophil infiltration, which subsided when mice were pretreated with the HMGB1 inhibitors soluble receptor for advanced glycation endproducts (sRAGEs) and HMGB1 A box protein. In case of using ROS quencher, there was decrease in UV-induced HMGB1 secretion in conjunctival epithelial cells and mice. Considering that UV-induced chronic inflammation causes ocular surface change as pterygium, we have confirmed high HMGB1 translocation and ROS expression in human pterygium. Our findings therefore revealed a previously unknown mechanism of UV-induced ocular inflammation related to ROS and HMGB1 suggesting a new medical therapeutic target.

Whole Breast Ultrasound: Comparison of the Visibility of Suspicious Lesions with Automated Breast Volumetric Scanning Versus Hand-Held Breast Ultrasound

RATIONALE AND OBJECTIVES

To assess how well radiologists visualize relevant features of lesions seen with automated breast volumetric scanning (ABVS) in comparison to hand-held breast ultrasound in women going to breast biopsy.

MATERIALS AND METHODS

Twenty-five subjects were recruited from women who were scheduled to undergo a breast biopsy for at least one Breast Imaging-Reporting and Data System four or five lesion identified in a diagnostic setting. In this institutional review board-approved study, the subjects underwent imaging of the breast(s) of concern using a dedicated system that allowed both hand-held breast ultrasound and ABVS. Five experienced breast radiologists reviewed the 30 lesions in 25 subjects in a reader study. Each reader was asked to specify the lesion type, size, imaging features, Breast Imaging-Reporting and Data System, and suspicion of malignancy and to compare the lesion characteristics of shape and margins between the two modalities.

RESULTS

Seven (23.3%) masses were malignant and 23 (76.4%) were benign. Across all lesions regardless of size or final pathology, there was no significant difference in sensitivity or specificity (P > .15) between the two modalities. For malignant lesions, the reader visualization confidence scores between the two ultrasound modalities were not significantly different (P > .1). However, analysis for nonmalignant cases showed a statistically significant increase in reader visualization confidence in lesion shape and margins (P < .001).

CONCLUSIONS

Radiologists showed increased confidence in visualization of benign masses and equal confidence in suspicious masses with ABVS imaging. This information could help decrease the need for additional hand-held imaging after automated whole breast ultrasound.

Using computer-extracted image features for modeling of error-making patterns in detection of mammographic masses among radiology residents

PURPOSE

Mammography is the most widely accepted and utilized screening modality for early breast cancer detection. Providing high quality mammography education to radiology trainees is essential, since excellent interpretation skills are needed to ensure the highest benefit of screening mammography for patients. The authors have previously proposed a computer-aided education system based on trainee models. Those models relate human-assessed image characteristics to trainee error. In this study, the authors propose to build trainee models that utilize features automatically extracted from images using computer vision algorithms to predict likelihood of missing each mass by the trainee. This computer vision-based approach to trainee modeling will allow for automatically searching large databases of mammograms in order to identify challenging cases for each trainee.

METHODS

The authors' algorithm for predicting the likelihood of missing a mass consists of three steps. First, a mammogram is segmented into air, pectoral muscle, fatty tissue, dense tissue, and mass using automated segmentation algorithms. Second, 43 features are extracted using computer vision algorithms for each abnormality identified by experts. Third, error-making models (classifiers) are applied to predict the likelihood of trainees missing the abnormality based on the extracted features. The models are developed individually for each trainee using his/her previous reading data. The authors evaluated the predictive performance of the proposed algorithm using data from a reader study in which 10 subjects (7 residents and 3 novices) and 3 experts read 100 mammographic cases. Receiver operating characteristic (ROC) methodology was applied for the evaluation.

RESULTS

The average area under the ROC curve (AUC) of the error-making models for the task of predicting which masses will be detected and which will be missed was 0.607 (95% CI,0.564-0.650). This value was statistically significantly different from 0.5 (p<0.0001). For the 7 residents only, the AUC performance of the models was 0.590 (95% CI,0.537-0.642) and was also significantly higher than 0.5 (p=0.0009). Therefore, generally the authors' models were able to predict which masses were detected and which were missed better than chance.

CONCLUSIONS

The authors proposed an algorithm that was able to predict which masses will be detected and which will be missed by each individual trainee. This confirms existence of error-making patterns in the detection of masses among radiology trainees. Furthermore, the proposed methodology will allow for the optimized selection of difficult cases for the trainees in an automatic and efficient manner.

Predictors of pain experienced by women during percutaneous imaging-guided breast biopsies

PURPOSE

The purpose of this study was to evaluate pain experienced during imaging-guided core-needle breast biopsies and to identify factors that predict increased pain perception during procedures.

METHODS

In this institutional review board-approved, HIPAA-compliant protocol, 136 women undergoing stereotactically or ultrasound-guided breast biopsy or cyst aspiration were recruited and provided written informed consent. Participants filled out questionnaires assessing anticipated biopsy pain, ongoing breast pain, pain experienced during biopsy, catastrophic thoughts about pain during biopsy, anxiety, perceived communication with the radiologist, chronic life stress, and demographic and medical information. Procedure type, experience level of the radiologist performing the biopsy, number of biopsies, breast density, histology, and tumor size were recorded for each patient. Data were analyzed using Spearman's ρ correlations and a probit regression model.

RESULTS

No pain (0 out of 10) was reported by 39.7% of women, mild pain (1-3 out of 10) by 48.5%, and moderate to severe pain (≥4 out of 10) by 11.8% (n = 16). Significant (P < .05) predictors of greater biopsy pain in the probit regression model included younger age, greater prebiopsy breast pain, higher anticipated biopsy pain, and undergoing a stereotactic procedure. Anticipated biopsy pain correlated most strongly with biopsy pain (β = .27, P = .004).

CONCLUSIONS

Most patients report minimal pain during imaging-guided biopsy procedures. Women experiencing greater pain levels tended to report higher anticipated pain before the procedure. Communication with patients before biopsy regarding minimal average pain reported during biopsy and encouragement to make use of coping strategies may reduce patient anxiety and anticipated pain.

Radiogenomic analysis of breast cancer: luminal B molecular subtype is associated with enhancement dynamics at MR imaging

PURPOSE

To investigate associations between breast cancer molecular subtype and semiautomatically extracted magnetic resonance (MR) imaging features.

MATERIALS AND METHODS

Imaging and genomic data from the Cancer Genome Atlas and the Cancer Imaging Archive for 48 patients with breast cancer from four institutions in the United States were used in this institutional review board approval-exempt study. Computer vision algorithms were applied to extract 23 imaging features from lesions indicated by a breast radiologist on MR images. Morphologic, textural, and dynamic features were extracted. Molecular subtype was determined on the basis of genomic analysis. Associations between the imaging features and molecular subtype were evaluated by using logistic regression and likelihood ratio tests. The analysis controlled for the age of the patients, their menopausal status, and the orientation of the MR images (sagittal vs axial).

RESULTS

There is an association (P = .0015) between the luminal B subtype and a dynamic contrast material-enhancement feature that quantifies the relationship between lesion enhancement and background parenchymal enhancement. Cancers with a higher ratio of lesion enhancement rate to background parenchymal enhancement rate are more likely to be luminal B subtype.

CONCLUSION

The luminal B subtype of breast cancer is associated with MR imaging features that relate the enhancement dynamics of the tumor and the background parenchyma.

Radiology resident mammography training: interpretation difficulty and error-making patterns

RATIONALE AND OBJECTIVES

The purpose of this study was to better understand the concept of mammography difficulty and how it affects radiology resident performance.

MATERIALS AND METHODS

Seven radiology residents and three expert breast imagers reviewed 100 mammograms, consisting of bilateral medial lateral oblique and craniocaudal views, using a research workstation. The cases consisted of normal, benign, and malignant findings. Participants identified abnormalities and scored the difficulty and malignant potential for each case. Resident performance (sensitivity, specificity, and area under the receiver operating characteristic curve [AUC]) was calculated for self- and expert-assessed high and low difficulties.

RESULTS

For cases classified by self-assessed difficulty, the resident AUCs were 0.667 for high difficulty and 0.771 for low difficulty cases (P = .010). Resident sensitivities were 0.707 for high and 0.614 for low difficulty cases (P = .113). Resident specificities were 0.583 for high and 0.905 for low difficulty cases (P < .001). For cases classified by expert-assessed difficulty, the resident AUCs were 0.583 for high and 0.783 for low difficulty cases (P = .001). Resident sensitivities were 0.558 for high and 0.796 for low difficulty cases (P < .001). Resident specificities were 0.714 for high and 0.740 for low difficulty cases (P = .807).

CONCLUSIONS

Increased self- and expert-assessed difficulty is associated with a decrease in resident performance in mammography. However, while this lower performance is due to a decrease in specificity for self-assessed difficulty, it is due to a decrease in sensitivity for expert-assessed difficulty. These trends suggest that educators should provide a mix of self- and expert-assessed difficult cases in educational materials to maximize the effect of training on resident performance and confidence.

Supine linac treatment versus tomotherapy in craniospinal irradiation: planning comparison and dosimetric evaluation

Craniospinal irradiation (CSI) is the standard treatment of primary intracranial tumour with risk of leptomeningeal dissemination. However, supine setup field-in-field technique does not need inter-fractional junction shift. Recently, the studies of CSI with tomotherapy showed excellent target coverage and tolerable normal organ dose in paediatric patients. The planning comparison and dosimetric difference between conventional radiotherapy and tomotherapy are presented. Three patients with central nervous system germinoma received supine CSI treatment. Normal tissue complication probability calculation was performed for parotid gland, kidney, lens, small bowel, ovary and testis. Homogenous vertebral body coverage for tomotherapy compared with conformal radiotherapy was found. The mean dose to each parotid gland decreased by 7.3 and 10 Gy, respectively, with tomotherapy. The volume of oesophagus and small bowel receiving >10 Gy was significantly lower. The V2, V5, V10 and V20 of the lungs are 81.6, 12.4, 2.3 and 0 % with tomotherapy. Tomotherapy showed excellent homogenous dose distribution through the craniospinal axis (PTV) and higher conformity index.

Salmonella contamination in shell eggs exposed to modified-pressure imaging for microcrack detection

Microcracks in egg shells are a food safety risk and are difficult for professional human graders to detect. Modified-pressure imaging technology with 99.6% accuracy has been developed to detect microcracks. This study was conducted to determine whether the microcrack detection system would increase penetration of Salmonella into egg contents or lead to cross-contamination within the system. Thirty dozen grade A large white retail eggs were used for each of 3 replicates. Cracked eggs were removed and 72 eggs/replicate were dip inoculated in buffered peptone water containing 10(5) cfu/mL of nalidixic acid-resistant Salmonella Typhimurium (ST), whereas 144 eggs were dipped in sterile buffered peptone water. All eggs were incubated overnight at 25°C before imaging. Forty-five eggs of each treatment were imaged in the following order: control, inoculated, control. Imaged and nonimaged eggs from each treatment were used for cultural analysis of a shell rinse, shell emulsion, and contents sample for each egg. The ST levels were monitored on brilliant green sulfa agar with 200 mg/L of nalidixic acid. Egg contents were also enriched to determine the prevalence of ST in low levels. Salmonella Typhimurium was not detected on or in any of the control eggs, including the eggs imaged after the inoculated eggs. The highest level of ST was detected in inoculated shell emulsions (4.79 log cfu/mL). No differences in ST levels were found for any sample location between imaged and nonimaged inoculated eggs. Therefore, the modified-pressure imaging system for microcrack detection did not result in microbial cross-contamination or increase the level of microbial penetration in inoculated eggs. The imaging system can be used to assess eggs for cracks without negative food safety implications.

Modified pressure imaging for egg crack detection and resulting egg quality

Cracks in the shell surface compromise the primary barrier for external microbial contamination of the egg. Microcracks are very small cracks in the shell surface that are difficult to detect by human graders. New technology has been developed that uses modified pressure and imaging to detect microcracks in eggs. Research has shown the system to have an accuracy of 99.6% in detecting both cracked and intact eggs. A study was undertaken to determine if quality differences existed between modified pressure imaged and control eggs during extended cold storage. Three replicates were conducted with eggs stored at 4 degrees C for 5 wk with weekly quality testing. The physical quality factors monitored were Haugh units, albumen height, egg weight, shell strength, vitelline membrane strength and elasticity, and whole egg total solids. All measurements were conducted on individual eggs (12/treatments per replicate) each week with the exception of whole egg solids, which were determined from 3 pools (4 eggs each)/treatment per replicate each week. Percentage of whole egg total solids was the only significant difference (P < 0.05) between treatments (23.65% modified pressure imaged and 23.47% control). There was a significant difference (P < 0.05) for egg weight between replicates (60.82, 58.02, and 60.58 g for replicates 1, 2, and 3, respectively). Therefore, imaging eggs in the modified pressure system for microcrack detection did not alter egg quality during extended cold storage. Utilizing the modified pressure crack detection technology would result in fewer cracked eggs reaching the consumer, consequently enhancing food safety without affecting product quality.

Cancer cases from ACRIN digital mammographic imaging screening trial: radiologist analysis with use of a logistic regression model

PURPOSE

To determine which factors contributed to the Digital Mammographic Imaging Screening Trial (DMIST) cancer detection results.

MATERIALS AND METHODS

This project was HIPAA compliant and institutional review board approved. Seven radiologist readers reviewed the film hard-copy (screen-film) and digital mammograms in DMIST cancer cases and assessed the factors that contributed to lesion visibility on both types of images. Two multinomial logistic regression models were used to analyze the combined and condensed visibility ratings assigned by the readers to the paired digital and screen-film images.

RESULTS

Readers most frequently attributed differences in DMIST cancer visibility to variations in image contrast--not differences in positioning or compression--between digital and screen-film mammography. The odds of a cancer being more visible on a digital mammogram--rather than being equally visible on digital and screen-film mammograms--were significantly greater for women with dense breasts than for women with nondense breasts, even with the data adjusted for patient age, lesion type, and mammography system (odds ratio, 2.28; P < .0001). The odds of a cancer being more visible at digital mammography--rather than being equally visible at digital and screen-film mammography--were significantly greater for lesions imaged with the General Electric digital mammography system than for lesions imaged with the Fischer (P = .0070) and Fuji (P = .0070) devices.

CONCLUSION

The significantly better diagnostic accuracy of digital mammography, as compared with screen-film mammography, in women with dense breasts demonstrated in the DMIST was most likely attributable to differences in image contrast, which were most likely due to the inherent system performance improvements that are available with digital mammography. The authors conclude that the DMIST results were attributable primarily to differences in the display and acquisition characteristics of the mammography devices rather than to reader variability.

Accuracy of computerized frameless stereotactic image-guided pedicle screw placement into previously fused lumbar spines

STUDY DESIGN

A retrospective chart and radiographic review of 122 pedicle screws placed with computerized stereotactic image-guidance into posterolateral fusion masses.

OBJECTIVES

To determine the accuracy rate of computerized stereotactic image-guided pedicle screw placement in previously fused lumbar spines.

SUMMARY OF BACKGROUND DATA

Placement of pedicle screws into a previously fused lumbar spine is challenging. The normal anatomic landmarks used to determine the starting point and trajectory of the screws have either been removed or are obscured by the fusion mass. Computerized frameless stereotaxis provides precise intraoperative real time multiplanar image-guidance and may be valuable in this clinical situation.

METHODS

Computerized frameless stereotactic image-guidance was used to place pedicle screws into 78 consecutive patients with prior lumbar spine fusions. Postoperative computed tomography was available on 35 patients (231 screws). One hundred and twenty-two screws were placed into fusion masses. Pedicle cortical perforations were characterized by the direction (medial, inferior, lateral, or superior) and magnitude (in 2-mm increments) of perforation.

RESULTS

Five (4.1%) of the 122 pedicle screws placed into previously fused levels were found to have unintentional cortical violations. There were 1 superior (<2 mm), 1 medial (<2 mm), and 3 lateral perforations (<2, 4, and 6 mm). None of these perforations led to clinically apparent radicular pain or weakness. No pedicle screws required revision for malpositioning.

CONCLUSIONS

The accuracy rate of stereotactic image-guided pedicle screw placement into previously fused lumbar spine levels is 96%. Computerized stereotactic image-guidance may have particular application in situations in which posterior element anatomy is altered, such as in the presence of a prior fusion mass.

Symptomatic spondylolysis: diagnosis and treatment

PURPOSE OF REVIEW

Approximately 35% of adolescents experience back pain. In athletic adolescents, spondylolysis is the most common offending cause. With growing numbers of adolescents participating in sports with higher levels of intensity, spondylolysis is becoming an increasingly common clinical problem.

RECENT FINDINGS

A recent report demonstrated the benign natural history of asymptomatic spondylolysis. However, long-term follow-up studies of patients who experience painful spondylolysis as adolescents remain unavailable. Modern imaging modalities have led to earlier diagnosis with greater accuracy. Conservative management with bracing continues to be a mainstay of treatment. In patients who are not helped by conservative therapy, recent studies have demonstrated the satisfactory long-term results of surgical repair.

SUMMARY

The long-term sequelae of symptomatic spondylolysis and unhealed pars defects require investigation. MRI promises to be a valuable tool for diagnosis and clinical stratification, but further studies are necessary to demonstrate its clinical utility.

Biosynthesis and local sequence specific degradation of poly(3-hydroxyvalerate-co-4-hydroxybutyrate) in Hydrogenophaga pseudoflava

A novel copolymer that consisted of 3-hydroxyvalerate and 4-hydroxybutyrate, P(3HV-co-4HB), was synthesized in Hydrogenophaga pseudoflava by growing it in media containing gamma-valerolactone and gamma-butyrolactone as a carbon source. The monomer ratio in the copolymer was changed by altering the feed ratio of the two lactones. The cultivation technique was composed of three steps: the first-step for high cell production in Luria-Bertani medium, the second-step for intracellular degrading removal of poly(3-hydroxybutyrate) (P(3HB)), which was formed in the first step, by culturing the cells in carbon-source-free medium, and the final step for accumulation of P(3HV-co-4HB) in a mixed lactone medium. All the P(3HV-co-4HB) copolymers contained less than 1 mol % of 3HB unit. These copolymers were characterized by NMR spectroscopy, differential scanning calorimetry, wide-angle X-ray diffraction, and first-order kinetic analysis of intracellular degradation. The copolymer with an approximately equal ratio of the comonomers was found amorphous. The NMR microstructural analysis showed that the copolymers contained appreciable amounts of 3HV-rich or 4HB-rich chains. The (13)C NMR splitting patterns associated with the four carbons in the 4HB unit of P(3HV-co-4HB) bear close resemblance to those observed in the 4HB unit of P(3HB-co-4HB). The signals arising from the carbons in the 3HV unit of P(3HV-co-4HB) split in a manner similar to those in the 3HB unit of P(3HB-co-4HB). Thus the sequences were assigned by comparing the NMR splittings for P(3HV-co-4HB) with those for P(3HB-co-4HB) and P(3HB-co-3HV). The sequence assignment was further checked by comparing the signal intensities before and after degradation of the copolymers. This was considered reasonable because the H. pseudoflava intracellular PHA depolymerase is more specific to the 3HV unit than to the 4HB unit, which was also confirmed by the higher degradation rate constant for the 3HV unit in the first-order kinetic analysis.

No association of the TGF-beta1 gene polymorphisms with the renal progression in autosomal dominant polycystic kidney disease (ADPKD) patients

BACKGROUND

Two genetic loci, PKD I and PKD2, have been identified as being responsible for ADPKD, and PKD1 is known to be associated with a poor prognosis. However, the presence of an intrafamilial study clinical diversity suggests that there are disease-modifying loci. Because the mechanism ofthe renal failure in ADPKD includes a cystic growth and tubulointerstitial atrophy and fibrosis, we studied the associations between 2 polymorphisms in the TGF-beta1 gene, which are known to be associated with chronic tubulointerstitial inflammation, and ADPKD progression in Korean patients.

PATIENTS AND METHODS

One hundred and twenty-five individuals who had ADPKD and 47 normal control subjects were genotyped by PCR-RFLP, the T869C (Leu10Pro) variant of TGF-beta gene leader sequence was discriminated with MspA1I and the G915C (Arg25Pro) variants with Bg1I. Statistical significances were determined using the Chi-square test.

RESULTS

The distribution of the alleles for the TGF beta1 Leu10Pro polymorphism in ADPKD was: T 54%, C 46%, which was similar to the Korean (56: 44, p = 0.887) and Western controls (65: 35). In addition, no differences were found between the ESRD and the non-ESRD groups (p = 0.888) or the early hypertension and the normotension groups (p = 0.249). The distribution of alleles for the TGF beta1 Arg25Pro polymorphism showed only the GG type which was different from the Western population controls (G:C = 90:10, p = 0.000).

CONCLUSIONS

Our results suggest that the polymorphism at Arg25Pro of TGF-beta1 in the Korean population has an allele distribution different from that ofthe Western population and that the polymorphism at Leu10Pro of TGF-beta1 has no association with the renal progression in Korean ADPKD patients.

Intracellular degradation of two structurally different polyhydroxyalkanoic acids accumulated in Pseudomonas putida and Pseudomonas citronellolis from mixtures of octanoic acid and 5-phenylvaleric acid

From a set of mixed carbon sources, 5-phenylvaleric acid (PV) and octanoic acid (OA), polyhydroxyalkanoic acid (PHA) was separately accumulated in the two pseudomonads Pseudomonas putida BM01 and Pseudomonas citronellolis (ATCC 13674) to investigate any structural difference between the two PHA accumulated under a similar culture condition using one-step culture technique. The resulting polymers were isolated by chloroform solvent extraction and characterized by fractional precipitation and differential scanning calorimetry. The solvent fractionation analysis showed that the PHA synthesized by P. putida was separated into two fractions, 3-hydroxy-5-phenylvalerate (3HPV))-rich PHA fraction in the precipitate phase and 3-hydroxyoctanoate (3HO)-rich PHA fraction in the solution phase whereas the PHA produced by P. citronellolis exhibited a rather little compositional separation into the two phases. According to the thermal analysis, the P. putida PHA exhibited two glass transitions indicative of the PHA not being homogeneous whereas the P. citronellolis PHA exhibited only one glass transition. It was found that the structural heterogeneity of the P. putida PHA was caused by a significant difference in the assimilation rate between PV and OA. The structural heterogeneity present in the P. putida PHA was also confirmed by a first order degradation kinetics analysis of the PHA in the cells. The two different first-order degradation rate constants (k(1)), 0.087 and 0.015/h for 3HO- and 3HPV-unit, respectively, were observed in a polymer system over the first 20 h of degradation. In the later degradation period, the disappearance rate of 3HO-unit was calculated to be 0.020 h. The k(1) value of 0.083/h, almost the same as for the 3HO-unit in the P. putida PHA, was obtained for the P(3HO) accumulated in P. putida BM01 grown on OA as the only carbon source. In addition, the k(1) value of 0.015/h for the 3HPV-unit in the P. putida PHA, was also close to 0.019/h for the P(3HPV) homopolymer accumulated in P. putida BM01 grown on PV plus butyric acid. On the contrary, the k(1) values for the P. citronellolis PHA were determined to be 0.035 and 0.029/h for 3HO- and 3HPV-unit, respectively, thus these two relatively close values implying a random copolymer nature of the P. citronellolis PHA. In addition, the faster degradation of P(3HO) than P(3HPV) by the intracellular P. putida PHA depolymerase indicates that the enzyme is more specific against the aliphatic PHA than the aromatic PHA.

Hetero-Diels-Alder reactions of alpha-aryl-beta-monohalo-alpha-nitrosoethylenes: diastereoselective synthesis of 6-substituted 3-aryl-4-halo-5,6-dihydro-4H-1,2-oxazines

Treatment of alpha-aryl-beta-bromo(or chloro)-alpha-nitrosoethylene, prepared in situ from alpha-monobromo(or chloro)ketoximes and sodium carbonate in ether at rt, with allytrimethylsilane afforded exclusively trans-(4S,6S)- and trans-(4R,6R)-3-aryl-4-halo-6-[(trimethylsilyl)methyl]-5,6-dihydro-4H-1,2-oxazines 10 albeit in low yields. Similar treatment of beta-halo-alpha-nitrosoethylenes with ethyl vinyl ether, however, gave single stereoisomers, i.e., cis-(4S,6S)- and cis-(4R,6R)-6-ethoxy-4-halo-5,6-dihydro-4H-1,2-oxazines 11, in moderate to good yields. The result is in contrast to the reported predominant formation of trans-11a by a radical reaction. On the other hand, similar reactions with tert-butyl vinyl ether at 30 degrees C gave diastereomeric mixtures of cis-(4S,6S)-, cis-(4R,6R)-, trans-(4S,6R)-, and trans-(4R,6S)-6-(tert-butoxy)-4-halo-5,6-dihydro-4H-1,2-oxazines 12. In contrast to compounds 11, the major isomers have (4S,6R) and (4R,6S) configurations. The tendency of a [4 + 2] cycloaddition reaction is consistent with that observed in the Diels-Alder reaction with inverse-electron demand. The stereochemistries of compounds 10-12 were assigned on the basis of the (1)H NMR coupling constants, which were unambiguously determined by the decoupling experiments. All reactions leading to compounds 10-12 proceed with very high regioselectivity. Diastereoselectivity and high regioselectivity are understood in terms of the frontier orbital method. It has been found that cis-12g is isomerized to a mixture of stereoisomers in favor of the trans-isomer in the presence of HClO(4) (72%) in CHCl(3) at rt.

Accumulation of polyhydroxyalkanoic acid containing large amounts of unsaturated monomers in Pseudomonas fluorescens BM07 utilizing saccharides and its inhibition by 2-bromooctanoic acid

A psychrotrophic bacterium, Pseudomonas fluorescens BM07, which is able to accumulate polyhydroxyalkanoic acid (PHA) containing large amounts of 3-hydroxy-cis-5-dodecenoate unit up to 35 mol% in the cell from unrelated substrates such as fructose, succinate, etc., was isolated from an activated sludge in a municipal wastewater treatment plant. When it was grown on heptanoic acid (C(7)) to hexadecanoic acid (C(16)) as the sole carbon source, the monomer compositional characteristics of the synthesized PHA were similar to those observed in other fluorescent pseudomonads belonging to rRNA homology group I. However, growth on stearic acid (C(18)) led to no PHA accumulation, but instead free stearic acid was stored in the cell. The existence of the linkage between fatty acid de novo synthesis and PHA synthesis was confirmed by using inhibitors such as acrylic acid and two other compounds, 2-bromooctanoic acid and 4-pentenoic acid, which are known to inhibit beta-oxidation enzymes in animal cells. Acrylic acid completely inhibited PHA synthesis at a concentration of 4 mM in 40 mM octanoate-grown cells, but no inhibition of PHA synthesis occurred in 70 mM fructose-grown cells in the presence of 1 to 5 mM acrylic acid. 2-Bromooctanoic acid and 4-pentenoic acid were found to much inhibit PHA synthesis much more strongly in fructose-grown cells than in octanoate-grown cells over concentrations ranging from 1 to 5 mM. However, 2-bromooctanoic acid and 4-pentenoic acid did not inhibit cell growth at all in the fructose media. Especially, with the cells grown on fructose, 2-bromooctanoic acid exhibited a steep rise in the percent PHA synthesis inhibition over a small range of concentrations below 100 microM, a finding indicative of a very specific inhibition, whereas 4-pentenoic acid showed a broad, featureless concentration dependence, suggesting a rather nonspecific inhibition. The apparent inhibition constant K(i) (the concentration for 50% inhibition of PHA synthesis) for 2-bromooctanoic acid was determined to be 60 microM, assuming a single-site binding of the inhibitor at a specific inhibition site. Thus, it seems likely that a coenzyme A thioester derivative of 2-bromooctanoic acid specifically inhibits an enzyme linking the two pathways, fatty acid de novo synthesis and PHA synthesis. We suggest that 2-bromooctanoic acid can substitute for the far more expensive (2,000 times) and cell-growth-inhibiting PHA synthesis inhibitor, cerulenin.

Potential of adenoviral p53 gene therapy and irradiation for the treatment of malignant gliomas

We investigated the combined effects of p53 gene transfer and irradiation and its still unclear interaction mechanism in human gliomas. Four human glioma cell lines expressing mutant type p53 (U373 and A172) and wild-type p53 (D54MG and EFC-2) were transfected by adenoviral vectors bearing p53 gene at 50 multiplicity of infection. Two days after transfection, cells were irradiated (3, 6, and 9 Gy). The cytotoxicity was evaluated by clonogenic assay. The quantitative analysis of apoptosis and cell cycle analysis were performed using flow cytometry. Irradiation combined with adenoviral p53 transfection significantly increased cytotoxicity, which was additive in cell lines with wild-type p53 and more than additive in cell lines with mutant p53. The combination of two modalities increased the apoptotic population by 14% in A172 cells and 20% in D54 MG cells, which were the sum of apoptosis from each modality. Adenoviral p53 transfection increased the G1 phase fraction and concomitant decrease of radioresistant S phase fraction in A172 and D54MG cells. Our study demonstrated that p53 gene transfer combined with irradiation increased absolute cytotoxicity in human glioma cells used in this experiment. The interaction mechanism for increased cytotoxicity involved, in part, increased apoptosis and change of cell cycle profile.

Non-linear dynamic analysis of clozapine-induced electroencephalographic changes in schizophrenic patients--a preliminary study

1. In order to find the electroencephalographic (EEG) parameters that reflect the effect of clozapine in schizophrenic patients, the authors applied various non-linear analyses on multi-channel EEG data drawn from patients before and after a therapeutic trial of clozapine. 2. The correlation dimension was difficult to extract from our limited time series EEG data and the authors did not find a meaningful association with clozapine use. The primary Lyapunov exponent could be reliably calculated but also did not reflect the effect of clozapine. 3. However, the mutual cross-prediction (MCP) algorithm showed potentially meaningful results. The driving system was shifted to the frontal channels after a 4-week trial with clozapine. Moreover, MCP might have a value as a predictor of treatment response. 4. Although preliminary in nature, the MCP might have greater power for interpreting complex changes from channel to channel in EEG induced by clozapine.

Surface modification of polyhydroxyalkanoate films and their interaction with human fibroblasts

A poly(3-hydroxybutylate-co-hydroxyvalerate) (PHA) film containing 34 mol.% 3-hydroxyvalerate (Biopol D600P) was prepared by the solvent cast method using a 10 wt.% chloroform solution of PHA. The PHA film was exposed to an oxygen plasma glow discharge to produce peroxides on its surfaces. These peroxides were then used as catalysts for the polymerization of acrylic acid (AA) in order to prepare carboxyl group-introduced PHA (PHA-C). Insulin-immobilized PHA was prepared using the coupling reaction of PU-C with insulin. The surface-modified PHAs were then characterized by attenuated total reflection Fourier transform infrared spectroscopy, electron spectroscopy for chemical analysis, and a contact angle goniometer. The amounts of insulin directly coupled to the carboxyl groups on PHA-C and coupled to the terminus amino groups of the grafted polyethylene oxide were 2.9 and 0.8 microg cm(-2), respectively. The PHA water contact angle (75 degrees ) decreased with AA grafting (33 degrees ) and insulin immobilization (31 degrees ), thereby exhibiting the increased hydrophilicity of the modified PHAs. When compared with PHA and PHA-C, the proliferation of human fibroblasts in the presence of serum was significantly accelerated on the insulin-immobilized PHAs.

Preparation and characterization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microspheres for the sustained release of 5-fluorouracil

Biodegradable microspheres were prepared with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV, 85:15 by mole ratio of hydroxybutyrate to hydroxyvalerate) by an water-in-oil-in-water (W/O/W), oil-in-water (O/W) and oil-in-oil (O/O) solvent evaporation method for the sustained release of anti-cancer drug, 5-fluorouracil (5-FU) with controlling the fabrication conditions. The shape of microspheres prepared was relatively rough due to highly crystalline property of PHBV and spherical. The efficiency of 5-FU loading into the PHBV microsphere with O/O method was over 80% compared to that 7% for microspheres by O/W method and below 1% for microspheres by a conventional W/O/W method. However, the most desirable release pattern can be achieved from the O/W method due to the cosolvent effect. The effects of preparation conditions such as the type and amount of surfactant, initial amount of loaded drug, the temperature of solvent evaporation, and etc. on the morphology for W/O/W method were investigated. Possible mechanisms of the desirable sustained release pattern for O/W system have been proposed.

Surface characterization and in vitro blood compatibility of poly(ethylene terephthalate) immobilized with insulin and/or heparin using plasma glow discharge

Poly(ethylene terephthalate)(PET) film was exposed to oxygen plasma glow discharge to produce peroxides on its surfaces. These peroxides were then used as catalysts for the polymerization of acrylic acid (AA) in order to prepare a carboxylic acid group-introduced PET (PET-AA). Insulin and heparin co-immobilized PET (PET-I-H) was prepared by the grafting of poly(ethylene oxide) (PEO) on to PET-AA, followed by reaction first with insulin and then heparin. These surface-modified PETs were characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, electron spectroscopy for chemical analysis (ESCA), and a contact angle goniometer. The concentration of the heparin (1.23 microg/cm2) bound to the PEO-grafted PET (PET-PEO) was higher than that (0.77 microg/cm2) on the insulin-immobilized PET (PET-In). The blood compatibilities of the surface-modified PETs were examined using in vitro thrombus formation, plasma recalcification time (PRT), activated partial thromboplastin time (APTT), and platelet adhesion and activation. In the experiment with plasma proteins, the PRT and APTT were significantly prolonged for both the heparin-immobilized PET (PET-He) and the PET-I-H, suggesting the binding of immobilized heparin to antithrombin III. The percentage of platelet adhesion slightly increased with the introduction of AA on the PET surfaces, decreased with the introduction of PEO and insulin, and decreased further with the immobilization of heparin. The release of serotonin was highly suppressed on PET-He and PET-I-H, and on surface-modified PETs the percentage of its release increased with an increase in platelet adhesion.

Local sequence dependence of polyhydroxyalkanoic acid degradation in Hydrogenophaga pseudoflava

The first order intracellular degradation of various polyhydroxyalkanoic acid (PHA) inclusions in Hydrogenophaga pseudoflava cells was investigated by analyzing the compositional and microstructural changes of the PHA using gas chromatography, (13)C NMR spectroscopy, and differential scanning calorimetry. Two types of PHA, copolymers and blend-type polymers, were separately accumulated in cells for comparison. The constituent monomers were 3-hydroxybutyric acid (3HB), 4-hydroxybutyric acid (4HB), and 3-hydroxyvaleric acid (3HV). It was found that the 3HB-4HB copolymer was degraded only when the polymer contained a minimal level of 3HB units. With the cells containing a 3HB/4HB blend-type polymer, only poly(3HB) was degraded, whereas poly(4HB) was not degraded, indicating the totally inactive nature of the intracellular depolymerase against poly(4HB). On the basis of the magnitude of the first order degradation rate constants, the relative substrate specificity of the depolymerase toward the constituting monomer units was determined to decrease in the order 3HB > 3HV > 4HB. (13)C NMR resonances of the tetrad, triad, and dyad sequences were analyzed for the samples isolated before and after degradation experiments. The results showed that the intracellular degradation depended on the local monomer sequence of the copolymers. The relative substrate specificity of the depolymerase determined from the NMR local sequence analysis agreed well with that obtained from the kinetics analysis. It is suggested that, without isolation and purification of the intracellular PHA depolymerase and "native" PHA substrates, the relative specificity of the enzyme as well as the microstructural heterogeneity of the PHA could be determined by measuring in situ the first order degradation rate constants of the PHA in cells.

Production of poly(3-hydroxybutyric acid-co-4-hydroxybutyric acid) and poly(4-hydroxybutyric acid) without subsequent degradation by Hydrogenophaga pseudoflava

A Hydrogenophaga pseudoflava strain was able to synthesize poly(3-hydroxybutyric acid-co-4-hydroxybutyric acid) [P(3HB-co-4HB)] having a high level of 4-hydroxybutyric acid monomer unit (4HB) from gamma-butyrolactone. In a two-step process in which the first step involved production of cells containing a minimum amount of poly(3-hydroxybutyric acid) [P(3HB)] and the second step involved polyester accumulation from the lactone, approximately 5 to 10 mol% of the 3-hydroxybutyric acid (3HB) derived from the first-step culture was unavoidably reincorporated into the polymer in the second cultivation step. Reincorporation of the 3HB units produced from degradation of the first-step residual P(3HB) was confirmed by high-resolution 13C nuclear magnetic resonance spectroscopy. In order to synthesize 3HB-free poly(4-hydroxybutyric acid) [P(4HB)] homopolymer, a three-stage cultivation technique was developed by adding a nitrogen addition step, which completely removed the residual P(3HB). The resulting polymer was free of 3HB. However, when the strain was grown on gamma-butyrolactone as the sole carbon source in a synthesis medium, a copolyester of P(3HB-co-4HB) containing 45 mol% 3HB was produced. One-step cultivation on gamma-butyrolactone required a rather long induction time (3 to 4 days). On the basis of the results of an enzymatic study performed with crude extracts, we suggest that the inability of cells to produce 3HB in the multistep culture was due to a low level of 4-hydroxybutyric acid (4HBA) dehydrogenase activity, which resulted in a low level of acetyl coenzyme A. Thus, 3HB formation from gamma-butyrolactone is driven by a high level of 4HBA dehydrogenase activity induced by long exposure to gamma-butyrolactone, as is the case for a one-step culture. In addition, intracellular degradation kinetics studies showed that P(3HB) in cells was completely degraded within 30 h of cultivation after being transferred to a carbon-free mineral medium containing additional ammonium sulfate, while P(3HB-co-4HB) containing 5 mol% 3HB and 95 mol% 4HB was totally inert in interactions with the intracellular depolymerases. Intracellular inertness could be a useful factor for efficient synthesis of the P(4HB) homopolymer and of 4HB-rich P(3HB-co-4HB) by the strain used in this study.

Differential scanning calorimetric study of poly(3-hydroxyoctanoate) inclusions in bacterial cells

Medium chain length polyhydroxyalkanoates, MCL-PHAs, produced by bacteria as inclusion bodies or granules were analyzed in situ by differential scanning calorimetry (DSC) without isolation from the cells. The kinetic DSC study of PHA granules, which contained mostly 3-hydroxyoctanoate units (PHO), in Pseudomonas putida BM01 cells showed that the polymer within the granules existed in an amorphous state, but it crystallized after dehydration of the cells under freeze-drying condition (below -50 degrees C) followed by annealing at ambient temperature. In this manner, PHO within the cells readily crystallized to the maximum degree of crystallinity within 24 h at room temperature, which was much faster than for the same polymer isolated by solvent extraction. This observation suggests that the polymer within the cellular granules may be well organized. The DSC endothermic melting peak areas for the room-temperature annealed polymers within the cells were directly proportional to the amount of polymer in the cell, and the results from this type of quantitative analysis were essentially identical to those obtained by gas chromatographic and gravimetric analysis of the polymers. X-Ray diffraction analysis of the polymer in the freeze-dried, whole cells and of the isolated, fully crystallized polymer showed that the two types of PHO samples had similar crystal structures, but the polymer in the granules exhibited better side-chain packing and higher crystallinity.

Clinical results of 24 pituitary macroadenomas with linac-based stereotactic radiosurgery

PURPOSE

To determine the impact of stereotactic radiosurgery (SRS) on the clinical course, hormonal status, and follow-up CT/MRI scan of pituitary macroadenomas.

METHODS AND MATERIALS

From July 1988 to March 1996, 24 pituitary macroadenomas had been treated using 6 MV linear accelerator based SRS. They consisted of 11 (45.8%) prolactinomas, 2 (8.3%) growth hormone (GH)-secreting tumors, 1 (4.2%) Cushing's disease, 8 (33.3%) nonsecreting (nonfunctioning: NF) tumors, and 2 (8.3%) mixed prolactin-growth hormone (PRL-GH)-secreting tumors (M:F = 12:12; aged 21-61 years). Postoperative irradiation was performed in all cases except for the instance of Cushing's disease. The prescribed dose to tumor center varied from 10 to 27 Gy (mean 21.1 Gy) using a collimator size of 0.5 to 2.5 cm. The follow-up duration ranged from 13 to 89 months (mean 49.2 months). Results from these patients were compared to our results using conventional radiation.

RESULTS

Visual acuity and field defect were improved or became normal in 19 (79.2%) cases. Four (16.7%) remained unchanged after the treatment. One (4.1%) progressed 6 years after SRS and subsequently had repeat surgery with conventional boost irradiation. Of the 13 (46.4%) prolactinomas, including two mixed PRL-GH secreting tumors, 11 (84.1%) revealed normal hormonal levels within 1 year after SRS. In contrast, it took 2 years to become normal after conventional radiation therapy. In four GH-secreting tumors including two mixed PRL-GH secreting tumors, SRS and conventional methods showed similar responses. On follow-up imagings of the 21 patients, the mass was completely resolved in 4 (16.7%), including 3 PRLs and one NF, decreased in 11 (45.8%), and unchanged in 5 (16.7%) with central necrosis or cysts. One (4.2%) progressed and was reoperated 6 years after treatment. The complications related to SRS were comparable to those from conventional method.

CONCLUSION

Radiosurgery can be used effectively in patients with pituitary adenoma. In this study, a more rapid hormonal and clinical response was achieved with radiosurgery than with conventional pituitary irradiation treatment.

Computer-aided design optimization with the use of a fast dose model for linear-accelerator-based stereotactic radiosurgery

In order to efficiently plan non-spherical radiosurgical targets we have used computer-aided design optimization techniques with a fast dose model. A study of the spatial dose distribution for single or multiple non-coplanar arcs was carried out using a 18 cm diameter spherical head model. The dose distribution generated from the 3D dose computation algorithm can be represented by a simple analytic form. Two analytic dose models were developed to represent the dose for preset multiple non-coplanar arcs or a single arc: spherical and cylindrical. The spherical and cylindrical dose models compute dose quickly for each isocentre and single arc. Our approach then utilizes a computer-aided design optimization (CAD) with the use of two fast approximate dose models to determine the positions of isocentres and arcs. The implementation of CAD with fast dose models was demonstrated. While the fast dose models are only approximations of the true dose distribution, it is shown that this approximate model is sufficient to optimize isocentric position, collimator size and arc positions with CAD.

Biosynthesis of Novel Aromatic Copolyesters from Insoluble 11-Phenoxyundecanoic Acid by Pseudomonas putida BM01

Two types of novel aromatic copolyesters were synthesized from 11-phenoxyundecanoic acid (11-POU) as the sole carbon source and the cosubstrates 11-POU and octanoate, respectively, by isolated Pseudomonas putida BM01 that is known to accumulate high concentrations of medium-chain-length polyesters. Insoluble 11-POU was recrystallized in situ in buffer by alkaline treatment and pH adjustment, followed by autoclaving. The resulting microcrystals, whose structure was different from that of the commercially available crystalline powder, suspended in media were rapidly consumed by the bacterium. Synthesized polymers were characterized by gas chromatography, nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. The aromatic copolyesters synthesized from 11-POU were composed of two monomer units consisting of 3-hydroxy-5-phenoxyvalerate (5POHV) as the major component (72 to 85 mol%) and 3-hydroxy-7-phenoxyheptanoate (7POHH) as the minor component (15 to 28 mol%). The aromatic copolyesters showed a crystalline melting transition at 70(deg)C. When the bacterium was grown on the cosubstrates 11-POU and octanoate, the bacterium synthesized the copolyesters composed of aromatic and aliphatic monomers poly(5POHV-co-7POHH-co-3-hydroxy-9-phenoxynonanoate-co-3-hydroxyalkanoates) . The addition of octanoate in the feed shifted the major monomer unit in the polymer from 5POHV to 7POHH. A further-fragmented metabolite, 3-phenoxypropionate, whose concentration reached a steady state at the time of greatest polyester accumulation, was detected in the medium. The metabolic pathway of 11-POU is suggested.

Radioprotective effect of captopril on the mouse jejunal mucosa

PURPOSE

Captopril, an inhibitor of angiotensin I converting enzyme, has been shown to modify radiation damage and prevent radiation injury of normal tissue in rats and pigs. The present study was carried out to determine whether captopril would reduce radiation changes in the proximal small bowel in mice.

METHODS AND MATERIALS

Mice were subjected to whole body irradiation with 9 Gy or 15 Gy. Captopril was administered in drinking water at a regimen of 62.5 mg/kg/day (captopril group I) and 125 mg/kg/day (captopril group II), continuously from 7 days before irradiation to the end of each designed experiment. The jejunal damage was evaluated microscopically by crypt count per circumference and by histologic damage grading.

RESULTS

Crypt number in the sham-irradiated control was 133 +/- 6.8/circumference. In both captopril group I and II, crypt numbers and histologic scores were not significantly different from those in the normal group. The 9 Gy and 15 Gy radiation alone groups showed significantly lower crypt counts and histologic scores compared with the sham-irradiated control group (p < 0.05). The groups exposed to 9 Gy radiation plus captopril I and II showed significantly higher crypt counts and lower histologic damage scores on the third day, and lower histologic damage scores on the fifth day compared with the 9 Gy radiation alone group (p < 0.05). The 15 Gy radiation plus captopril I and II groups had significantly higher crypt counts and lower histologic damage scores on the third day than those of the 15 Gy radiation alone group (p < 0.05). All mice of the 15 Gy radiation group succumbed to intestinal radiation death.

CONCLUSION

Our results suggest that captopril provides protection from acute radiation damage to the jejunal mucosa in mice.

Polyester Biosynthesis Characteristics of Pseudomonas citronellolis Grown on Various Carbon Sources, Including 3-Methyl-Branched Substrates

Forty-two different carbon sources were tested for the polyester synthesis of a citronellol-utilizing bacterium, Pseudomonas citronellolis (ATCC 13674). These included linear C 2 to C 10 monocarboxylic acids, C 3 to C 10 dicarboxylic acids, saccharides, α,ω-diols, hydrocarbons, and 3-methyl-branched substrates such as 3,7-dimethyl-6-octen-1-ol (citronellol), 3-methyl- n -valerate, 3-methyl-1-butanol, and 3-methyladipate. Isolated polymers were characterized by gas chromatography, infrared spectroscopy, 1 H- or 13 C-nuclear magnetic resonance spectroscopy, 1 H- 13 C heteronuclear correlation spectroscopy ( 1 H- 13 C COSY), 1 H- 1 H homonuclear COSY, and differential scanning calorimetry. Polyesters from nine monocarboxylic acids and two related carbon sources could be metabolically divided into three groups. The first group of C 2 to C 4 carbon sources resulted in copolyesters composed of 61 to 70 mol% 3-hydroxydecanoate, 23 to 33 mol% 3-hydroxyoctanoate, 3.6 to 9.0 mol% 3-hydroxy-5- cis -dodecenoate, and 1.8 to 2.6 mol% 3-hydroxy-7- cis -tetradecenoate. Carbon sources in group II (C 7 to C 10 ) produced copolyesters composed of 3-hydroxyacid monomer units with the same number of carbon atoms as the substrate (major constituent) and monomer units with either two less or two more carbons. Negligible amounts of 3-hydroxy-5- cis -dodecenoate and 3-hydroxy-7- cis -tetradecenoate were detected in copolyesters from this group. Copolyesters from group III (C 5 and C 6 ) had a monomer unit distribution that could be said to be between those of groups I and II. In addition, a novel copolyester, poly(3-hydroxy-7-methyl-6-octenoate-co-3-hydroxy-5-methylhexanoate), was synthesized when grown on citronellol. The 1 H- 13 C heteronuclear COSY spectrum for monomer unit II revealed that both methylene and isopropyl groups, proximately connected in series to a single chiral center, had magnetically diastereotopic natures.

Optimisation of dose distribution for linear accelerator-based stereotactic radiosurgery

The work presented in the paper addresses a method for obtaining the optimal dose distribution for LINAC-based stereotactic radiosurgery. As many targets have nonspherical or irregular shapes and three-dimensional dose calculations included in dose optimisation, long computation times are required to determine the optimum isocentre separation and collimator sizes to shape the irregular target using the multiple-isocentre approach, by trial-and-error types of method. The simple approach, using a computer-aided design optimisation technique and a fast approximate dose model, has been developed to find the optimum isocentre positions and collimator sizes quickly and automatically. A spherical dose model has been developed to represent the dose for a standard arc system with a single isocentre. The implementation of computer-aided design algorithms with the spherical dose model and their application to several cases are discussed. It is shown that the spherical dose model gives dose distribution similar to that of the exact dose model, which makes this simple dose model more efficient, with computer-aided design optimisation, in finding optimum isocentre positions and collimator sizes used in stereotactic radiosurgery.

Stimulation of radiation-impaired plasminogen activator release by phorbol ester in aortic endothelial cells

Ionizing radiation has been reported to affect the fibrinolytic activity of exposed tissue. With cultured bovine aortic endothelial cells, radiation suppresses the release of plasminogen activator to the conditioned media, with a concomitant increase in intracellular plasminogen activator. Thus study was undertaken to determine whether radiation-impaired plasminogen activator release can be modified by phorbol ester. We exposed cultured bovine aortic endothelial cells to a sterilizing dose of 10 Gy of gamma-rays and found the treatment led to cell injury, as evidenced by an increased release of prelabeled chromium, and to a reduction of plasminogen activator in the conditioned media with elevated intracellular plasminogen activator in irradiated cells. Phorbol ester enhanced plasminogen activator activity in both sham-irradiated and irradiated endothelial cells. It was interesting to note that the increased plasminogen activator in phorbol ester-stimulated sham-irradiated cells was largely retained inside the cell, while it was released to the conditioned media in irradiated cells. Apparently, altered plasminogen activator activity of radiation-sterilized endothelial cells can be modified by exogenous stimuli.