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British Journal of Radiology [journal]
- The utility of atlas-assisted segmentation in the male pelvis is dependent on the inter-observer agreement of the structures segmented. [JOURNAL ARTICLE]
- Br J Radiol 2014 Aug 29.:20140299.
Objectives: To investigate the relationship between the ability of atlas based auto-segmentation to reduce outlining time in the male pelvis (body, bladder, rectum, femoral heads, prostate and seminal vesicles) and the inter-observer agreement in the delineation of these structures. To examine any increase of the inter-observer agreement with the use of an auto-segmentation tool. Methods: We created atlases in the Elekta ABAS system and recorded the time to delineate the above structures on 8 patients with and without its aid. We also measured the inter-observer agreement in the structure definitions using several metrics (Dice's Similarity Coefficient (DSC), Mean Distance to Conformity, Percentage Volume Difference) with and without its aid. Results: There is a high degree of correlation between the time saving with the use of ABAS and the degree of inter-observer agreement (r=0.90 for DSC). This indicates that for structures where inter-observer agreement is low (DSC<0.65) then ABAS does not reduce outlining time. We found that the inter-observer agreement is increased with ABAS only for the prostate. Conclusions: Outlining time saved in the male pelvis is highly correlated with the inter-observer agreement of the structures. Only for the prostate does the use of ABAS significantly reduce the amount of inter-observer variation in contouring. Advances in Knowledge: The use of auto-segmentation software increases the outlining time for structures where inter-observer agreement is low. Any increase in the inter-observer agreement in contouring with the aid of such software may be limited to those structures where there is currently mid-range agreement between observers.
- Prediction of pathologic complete response of breast cancer patients undergoing neoadjuvant chemotherapy: usefulness of Breast MRI computer-aided detection. [JOURNAL ARTICLE]
- Br J Radiol 2014 Aug 27.:20140142.
Purpose: The purpose of this study is to evaluate usefulness of MR CAD in patients undergoing neoadjuvant chemotherapy for prediction of tumor's pathologic complete response. Objective: 148 breast cancer patients (mean age: 47.3, range: 29-72 years) who underwent neoadjuvant chemotherapy included our study. They had taken MRI before and after neoadjuvant chemotherapy, and pathologic result reviewed as gold standard. Methods: Computer-generated kinetic features for each lesion were recorded, and features analyzed included "threshold enhancement" at 50% and 100% minimum thresholds; degree of initial peak enhancement; and enhancement profiles composed of lesion percentages of washout, plateau, and persistent enhancement. Final pathologic size and character of tumor was correlated with post-chemotherapy mammography, ultrasonography and MR CAD findings. Kruskal-Wallis test and intraclass correlation coefficient (ICC) were used to analysis. Results: We divided 148 patients as complete pathologic response group and non-complete pathologic response group. Complete pathologic response was defined as no histopathologic evidence of any residual invasive cancer cells in the breast or axillary lymph nodes. 39 patients showed complete pathologic response, 109 patients showed non-complete pathologic response. Between enhancement profiles of MR CAD, plateau proportion of tumor was significantly correlated with tumor's pathologic response (mean proportion of plateau on complete pathologic response group was 27%, p-value=0.007). Conclusion: When plateau proportion of tumor is high on MR CAD, we can predict non-complete pathologic response of neoadjuvant chemotherapy. Advances in knowledge: MR CAD can be a useful tool for the assessment of response to neoadjuvant chemotherapy and prediction of pathologic result.
- Diffusion-Weighted MR Imaging in Early Assessment of Tumor Response to Radiotherapy in high-risk Prostate Cancer. [JOURNAL ARTICLE]
- Br J Radiol 2014 Aug 27.:20140359.
Objectives: The objective of this study was to assess the efficacy of diffusion-weighted MRI (DWI) in monitoring the response to radiotherapy in high-risk prostate cancer. Materials and Methods: This retrospective study included 78 patients with high-risk prostate cancer undergoing 3.0 T MRI (supplemented by DWI) before and after Intensity Modulated Radiotherapy (IMRT). Based on follow-up clinical exams, patients were divided into two groups: the recurrence group (patients suffered biochemical/clinical recurrence within 3 years, n=13) and non-recurrence group (patients with over 3-years of recurrence-free, n=65). The apparent diffusion coefficient?ADC?values pre- and post-IMRT were compared between these two groups. The receiver-operating characteristics (ROC) analysis was carried out to investigate the discriminatory capability for pre- and post-IMRT ADC values. Results: The overall ADC values were 1.04± 0.18×10(-3)mm(2)/s for prostate cancers before IMRT, and 1.45± 0.15×10(-3)mm(2)/s after IMRT (P<0.001). A statistically significant difference in post-IMRT ADC values was noted between patients with and without recurrence (1.27 ± 0.14×10-3 mm(2)/s vs. 1.49 ± 0.12×10(-3)mm(2)/s, P<0.001), though there was no statistical difference between them in pre-IMRT ADC values (1.00 ± 0.17×10(-3)mm(2)/s vs. 1.05 ± 0.18×10(-3)mm(2)/s, P=0.31). ROC curve analysis revealed that the post-IMRT ADC values could help identify patients suffering recurrences (area under the curve 0.88, P<0.001) Conclusions: Marked increase in ADC values was observed in prostate cancer after radiotherapy, especially in good responders. DWI is a valuable tool for monitoring the response to radiotherapy. Advances in knowledge: This study examined the relationship between ADC changes and tumor response to treatment in prostate cancer.
- Measurement of breast density with Digital Breast Tomosynthesis- a systematic review. [JOURNAL ARTICLE]
- Br J Radiol 2014 Aug 22.:20140460.
Digital breast tomosynthesis (DBT) has gained acceptance as an adjunct to digital mammography (DM) in screening. Now that breast density reporting is mandated in several States in America, it is increasingly important that the methods of breast density measurement be robust, reliable and consistent. Breast density assessment with DBT needs some consideration since quantitative methods are modeled for 2D mammography. A review of methods used for breast density assessment with DBT was performed. Existing evidence shows Cumulus has better reproducibility than BIRADS but still suffers from subjective variability; MedDensity is limited by image noise, whilst Volpara and Quantra are robust and consistent. Reported BI-RADS inter-reader breast density agreement (k) ranged from 0.65 to 0.91, with inter-reader correlation (r) ranging from 0.7 to 0.93. The correlations (r) between BI-RADS and quantitative methods are: Cumulus (0.54 to 0.94); MedDensity (0.48 to 0.78). Reported agreement (k) between BI-RADS and Volpara is 0.953. Breast density correlation between DBT and 2-dimensional mammography ranged from 0.73 to 0.97, with agreement (k) ranging from 0.56 to 0.96. To avoid variability and provide more reliable breast density information for clinicians, automated volumetric methods are preferred.
- High intensity focused ultrasound ablation: An effective and safe treatment for secondary hypersplenism. [JOURNAL ARTICLE]
- Br J Radiol 2014 Aug 20.:20140374.
Objective: Hypersplenism is a common disease, The conventional treatment is splenectomy and partial splenic embolization (PSE), however, both of them have high complication rates and technical defects. Therefore, safer and more effective techniques should be considered for the treatment of hypersplenism. High intensity focused ultrasound (HIFU) may provide an effective and safe way for treatment of hypersplenism. Therefore, we conducted this study, thus assessing the safety, efficacy of HIFU in treatment of secondary hypersplenism. Methods: A total of 28 patients who suffered from secondary hypersplenism were treated with HIFU ablation. All patients underwent HIFU were closely followed-up over a year. Magnetic resonance imaging (MRI) scan was performed and the spleens were observed. Blood counts and liver function tests were also detected. Results: In the follow-up process, the levels of white blood cell and platelets in the blood after HIFU were significantly higher than those of levels before HIFU, liver function also improved after HIFU treatment. In addition, the symptoms were ameliorated significantly or even disappeared. The MRI showed that the ablation area had turned into a non-perfused volume, after twelve months of HIFU ablation, the ablated area shrank evidently, the local outline of the spleen showed a depression and formed lobular, and the splenic volume decreased. Conclusion: For the first time, we used HIFU ablation to treat secondary hypersplenism. Splenic HIFU ablation is a safe, effective and noninvasive approach for secondary hypersplenism, it not only expand indications of HIFU, but also provided better choice for the treatment of secondary hypersplenism.
- Random variation in rectal position during radiotherapy for prostate cancer is two to three times greater than that predicted from prostate motion. [JOURNAL ARTICLE]
- Br J Radiol 2014 Oct; 87(1042):20140343.
Objective: Radiotherapy for prostate cancer does not explicitly take into account daily variation in the position of the rectum. It is important to accurately assess accumulated dose (DA) to the rectum in order to understand the relationship between dose and toxicity. The primary objective of this work was to quantify systematic (Σ) and random (σ) variation in the position of the rectum during a course of prostate radiotherapy. Methods: The rectum was manually outlined on the kilo-voltage planning scan and 37 daily mega-voltage image guidance scans for 10 participants recruited to the VoxTox study. The femoral heads were used to produce a fixed point to which all rectal contours were referenced. Results: Σ [standard deviation (SD) of means] between planning and treatment was 4.2 mm in the anteroposterior (AP) direction and 1.3 mm left-right (LR). σ (root mean square of SDs) was 5.2 mm AP and 2.7 mm LR. Superior-inferior variation was less than one slice above and below the planning position. Conclusion: Our results for Σ are in line with published data for prostate motion. σ, however, was approximately twice as great as that seen for prostate motion. This suggests that DA may differ from planned dose in some patients treated with radiotherapy for prostate cancer. Advances in knowledge: This work is the first to use daily imaging to quantify Σ and σ of the rectum in prostate cancer. σ was found to be greater than published data, providing strong rationale for further investigation of individual DA.
- Cardiac CT for Myocardial Ischemia Detection and Characterization - Comparative Analysis. [JOURNAL ARTICLE]
- Br J Radiol 2014 Aug 19.:20140159.
The assessment of patients presenting with symptoms of myocardial ischemia remains one of the most common and challenging clinical scenarios faced by physicians. Current imaging modalities are capable of three-dimensional, functional, and anatomical views of the heart and as such offer a unique contribution to understanding and managing the pathology involved. Evidence has accumulated that visual anatomical coronary evaluation does not adequately predict hemodynamic relevance and should be complemented by physiological evaluation, highlighting the importance of functional assessment. Technical advances in CT technology over the last decade have progressively moved cardiac CT imaging into the clinical workflow. In addition to anatomical evaluation cardiac CT is capable of providing myocardial perfusion parameters. A variety of CT techniques can be used to assess the myocardial perfusion. The Single Energy First Pass CT (SE FPCT) and Dual Energy First Pass CT (SE FPCT) allow static assessment of myocardial blood pool. Dynamic cardiac CT imaging allows quantification of myocardial perfusion through time resolved attenuation data. CT-based myocardial perfusion imaging is showing promising diagnostic accuracy compared to the current reference modalities. The aim of this review is to present currently available myocardial perfusion techniques with a focus on CT imaging in light of recent clinical investigations.
- Vaginal displacement during course of adjuvant radiation for cervical cancer: results from a prospective IG-IMRT study. [JOURNAL ARTICLE]
- Br J Radiol 2014 Oct; 87(1042):20140428.
Objective: To compare internal target volume (ITV) generated using population-based displacements (ITV_study) with empty and full bladder scan fusion (ITV_EBFB) for organ-at-risk (OAR) doses during adjuvant intensity-modulated radiation therapy (IMRT) for cervical cancer. Methods: From January 2011 to October 2012, patients undergoing IMRT were included. CT simulation was carried out after inserting vault markers. Planning target volume (PTV)_EBFB received 50 Gy per 25 fractions. Pre-treatment megavoltage CT (MVCT) was performed. MVCTs were registered using bony landmarks with Day 1 MVCT. Displacement of the centre of mass of markers was measured along each axis. Directional ITV was calculated using mean ± 2 standard deviations (SDs) (ITV_study). Replanning was performed using PTV study, and OAR doses were compared with PTV_EBFB using Wilcoxon test. Results: A total of 348/386 data sets were evaluable for 16 patients. The median vaginal displacement was 1.2 mm (SD, 1.3 mm), 4.0 mm (SD, 3.5 mm) and 2.8 mm (SD, 3.3 mm) in the mediolateral, superoinferior and anteroposterior directions, respectively. The ITV margins were 4.1, 10.3 and 10.6 mm. ITV_study and ITV_EBFB were 115.2 cm(3) (87.7-152.2 cm(3)) and 151 cm(3) (95.7-277.1 cm(3)) (p < 0.0001), respectively. PTV_study and PTV_EBFB were 814 and 881 cm(3) (p < 0.0001), respectively. Median doses to the bladder were lower with the PTV_study (46.2 Gy vs 43.2 Gy; p = 0.0001), and a similar trend was observed in the volume of the small bowel receiving 40 Gy (68.2 vs 60.1 cm(3); p = 0.09). Conclusion: Population-based PTV margins can lead to reduction in OAR doses. Advances in knowledge: Population-based ITV may reduce OAR doses while executing adjuvant IMRT for cervical cancer.
- Multi-Centre Analysis of Incidental Findings on Low resolution CT Attenuation Correction (CTAC) Images. [JOURNAL ARTICLE]
- Br J Radiol 2014 Aug 19.:20130701.
Objectives: To review new incidental findings detected on low-resolution CT attenuation correction (CTAC) images acquired during SPECT-CT myocardial perfusion imaging (MPI). To determine whether the CTAC images had diagnostic value and warrant reporting. Methods: A multi-centre study was performed in four UK Nuclear Medicine departments. CTAC images acquired as part of MPI performed using SPECT were evaluated to identify incidental findings. New findings considered to be clinically significant were evaluated further. Positive predictive value (PPV) was determined at the time of definitive diagnosis. Results: Of 1819 patients studied, 497 (27%) had a positive CTAC finding. Fifty-one (2.8%) patients had findings that were clinically significant at the time of CTAC report and had not been previously diagnosed. Only 4 (0.2%) of these were potentially detrimental to patient outcome. Conclusion: One centre had a PPV of 0% and the study suggests that these CTAC images should not be reported. Two centres with more modern equipment had low PPVs of 0% and 6%, respectively, and further research is suggested prior to drawing a conclusion. The centre with best quality CT had a PPV of 67% and the study suggests that CTAC images from this equipment should be reported. Advances in knowledge: This study is unique compared with previous studies which have reported only the potential to identify incidental findings on low-resolution CT images. This study both identifies and evaluates new clinically significant incidental findings and it demonstrates that the benefit of reporting the CTAC images depends on the type of equipment used.
- Ability of 18-fludeoxyglucose positron emission tomography/CT to detect incidental cancer. [JOURNAL ARTICLE]
- Br J Radiol 2014 Oct; 87(1042):20140030.
Objective: To determine the prevalence and clinical features of pathologically proven incidental cancer (IC) detected by whole-body fluorine-18 fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)/CT, as well as the incidence of false-positive and false-negative results. Methods: We retrospectively reviewed reports derived from (18)F-FDG PET/CT images of 3079 consecutive patients with known or suspected malignancies for 3 years. Discrete focal uptake indicating IC was identified from reports as well as pathological or clinical diagnoses, and the clinical courses were investigated. The false-positive result was defined as uptake indicating IC but not pathologically confirmed as malignant during follow-up. The false-negative result was defined as pathologically proven IC detected by another modality at initial clinical work-up or diagnosed during the follow-up period. Results: We found (18)F-FDG uptake indicating IC in 6.7% of all patients, and IC was pathologically proven in 2.2% of all patients. The most common sites were the colon, lung and stomach. The median survival duration of patients with IC was 42 months. The results were false positive in 4.5% of all patients, and the results were false negative in 2.3% of all patients. Conclusion: (18)F-FDG PET/CT is a valuable tool for detecting IC. The rates of false-positive and false-negative results are within acceptable range. Advances in knowledge: This is the first report to describe the survival of patients with IC, and the detailed features of false-negative results at actual clinical settings.