Owen J. O’Connor

Emergency CT brain: preliminary interpretation with a tablet device: image quality and diagnostic performance of the Apple iPad

Tablet devices have recently been used in radiological image interpretation because they have a display resolution comparable to desktop LCD monitors. We identified a need to examine tablet display performance prior to their use in preliminary interpretation of radiological images. We compared the spatial and contrast resolution of a commercially available tablet display with a diagnostic grade 2 megapixel monochrome LCD using a contrast detail phantom. We also recorded reporting discrepancies, using the ACR RADPEER system, between preliminary interpretation of 100 emergency CT brain examinations on the tablet display and formal review on a diagnostic LCD. The iPad display performed inferiorly to the diagnostic monochrome display without the ability to zoom. When the software zoom function was enabled on the tablet device, comparable contrast detail phantom scores of 163 vs 165 points were achieved. No reporting discrepancies were encountered during the interpretation of 43 normal examinations and five cases of acute intracranial hemorrhage. There were seven RADPEER2 (understandable) misses when using the iPad display and 12 with the diagnostic LCD. Use of software zoom in the tablet device improved its contrast detail phantom score. The tablet allowed satisfactory identification of acute CT brain findings, but additional research will be required to examine the cause of “understandable” reporting discrepancies that occur when using tablet devices.

An assessment of medical students’ awareness of radiation exposures associated with diagnostic imaging investigations

ObjectivesThis study assessed students’ awareness of radiation exposures and determined the impact a curriculum in clinical radiology (CICR) had on awareness.MethodsSix hundred seventy medical students at one medical school were studied. CICR was delivered in yearly modules over the 5-year programme. Five hundred twenty-three students (years 1–5), exposed to increasing numbers of CICR modules and 147 students beginning medical school (year 0), represented the study and control groups, respectively. Students completed a multiple choice questionnaire assessing radiation knowledge and radiology teaching.ResultsMost students in the study population received CICR but 87% considered they had not received radiation protection instruction. The percentage of correctly answered questions was significantly higher in the study population than the control group (59.7% versus 38%, p < 0.001). Students who received CICR achieved higher scores than those who did not (61.3% compared with 42.8%, p < 0.001). Increasing exposure to CICR with each year of medical education was associated with improved performance.ConclusionsAssessment of students’ awareness of radiation exposures in diagnostic imaging demonstrates improved performance with increasing years in medical school and/or increasing exposure to CICR. Findings support the Euroatom 97 directive position, advocating implementation of radiation protection instruction into the undergraduate medical curriculum.

Minimization of radiation exposure due to computed tomography in inflammatory bowel disease.

Exposure to ionising radiation as a result of diagnostic imaging is increasing among patients with inflammatory bowel disease (IBD), primarily due to the more widespread use of computed tomography (CT). The potentially harmful effects of ionising radiation are a major cause for concern and radiologists, technologists and referring physicians who have a responsibility to the patient to ensure judicious use of those imaging modalities which result in exposure to ionising radiation and, when imaging is necessary, to ensure that a diagnostic quality imaging examination is acquired with lowest possible radiation exposure. This can be achieved by limiting the use of those imaging studies which involve ionising radiation to clinical situations where they are likely to change management, by implementing advances in low-dose CT technology, and, where feasible, by using alternative imaging modalities, such as ultrasonography or magnetic resonance imaging, which avoid radiation exposure.

The impact of routine open nonsuction drainage on fluid accumulation after thyroid surgery: a prospective randomised clinical trial

BackgroundThyroid drains following thyroid surgery are routinely used despite minimal supportive evidence. Our aim in this study is to determine the impact of routine open drainage of the thyroid bed postoperatively on ultrasound-determined fluid accumulation at 24 hours.MethodsWe conducted a prospective randomised clinical trial on patients undergoing thyroid surgery. Patients were randomly assigned to a drain group (n = 49) or a no-drain group (n = 44) immediately prior to wound closure. Patients underwent a neck ultrasound on day 1 and day 2 postoperatively. After surgery, we evaluated visual analogue scale pain scores, postoperative analgesic requirements, self-reported scar satisfaction at 6 weeks and complications.ResultsThere was significantly less mean fluid accumulated in the drain group on both day 1, 16.4 versus 25.1 ml (P-value = 0.005), and day 2, 18.4 versus 25.7 ml (P-value = 0.026), following surgery. We found no significant differences between the groups with regard to length of stay, scar satisfaction, visual analogue scale pain score and analgesic requirements. There were four versus one wound infections in the drain versus no-drain groups. This finding was not statistically significant (P = 0.154). No life-threatening bleeds occurred in either group.ConclusionsFluid accumulation after thyroid surgery was significantly lessened by drainage. However, this study did not show any clinical benefit associated with this finding in the nonemergent setting. Drains themselves showed a trend indicating that they may augment infection rates. The results of this study suggest that the frequency of acute life-threatening bleeds remains extremely low following abandoning drains. We advocate abandoning routine use of thyroid drains.Trial registrationISRCTN94715414

Optimizing parameters of an open-source airway segmentation algorithm using different CT images

Background Computed tomography (CT) helps physicians locate and diagnose pathological conditions. In some conditions, having an airway segmentation method which facilitates reconstruction of the airway from chest CT images can help hugely in the assessment of lung diseases. Many efforts have been made to develop airway segmentation algorithms, but methods are usually not optimized to be reliable across different CT scan parameters.MethodsIn this paper, we present a simple and reliable semi-automatic algorithm which can segment tracheal and bronchial anatomy using the open-source 3D Slicer platform. The method is based on a region growing approach where trachea, right and left bronchi are cropped and segmented independently using three different thresholds. The algorithm and its parameters have been optimized to be efficient across different CT scan acquisition parameters. The performance of the proposed method has been evaluated on EXACT’09 cases and local clinical cases as well as on a breathing pig lung phantom using multiple scans and changing parameters. In particular, to investigate multiple scan parameters reconstruction kernel, radiation dose and slice thickness have been considered. Volume, branch count, branch length and leakage presence have been evaluated. A new method for leakage evaluation has been developed and correlation between segmentation metrics and CT acquisition parameters has been considered.ResultsAll the considered cases have been segmented successfully with good results in terms of leakage presence. Results on clinical data are comparable to other teams’ methods, as obtained by evaluation against the EXACT09 challenge, whereas results obtained from the phantom prove the reliability of the method across multiple CT platforms and acquisition parameters. As expected, slice thickness is the parameter affecting the results the most, whereas reconstruction kernel and radiation dose seem not to particularly affect airway segmentation.ConclusionThe system represents the first open-source airway segmentation platform. The quantitative evaluation approach presented represents the first repeatable system evaluation tool for like-for-like comparison between different airway segmentation platforms. Results suggest that the algorithm can be considered stable across multiple CT platforms and acquisition parameters and can be considered as a starting point for the development of a complete airway segmentation algorithm.

CORK Study in Cystic Fibrosis: Sustained Improvements in Ultra-Low-Dose Chest CT Scores After CFTR Modulation With Ivacaftor

Background Ivacaftor produces significant clinical benefit in patients with cystic fibrosis (CF) with the G551D mutation. Prevalence of this mutation at the Cork CF Centre is 23%. This study assessed the impact of cystic fibrosis transmembrane conductance regulator modulation on multiple modalities of patient assessment. Methods Thirty‐three patients with the G551D mutation were assessed at baseline and prospectively every 3 months for 1 year after initiation of ivacaftor. Change in ultra‐low‐dose chest CT scans, blood inflammatory mediators, and the sputum microbiome were assessed. Results Significant improvements in FEV1, BMI, and sweat chloride levels were observed post‐ivacaftor treatment. Improvement in ultra‐low‐dose CT imaging scores were observed after treatment, with significant mean reductions in total Bhalla score (P < .01), peribronchial thickening (P = .035), and extent of mucous plugging (P < .001). Reductions in circulating inflammatory markers, including interleukin (IL)‐1&bgr;, IL‐6, and IL‐8 were demonstrated. There was a 30% reduction in the relative abundance of Pseudomonas species and an increase in the relative abundance of bacteria associated with more stable community structures. Posttreatment community richness increased significantly (P = .03). Conclusions Early and sustained improvements on ultra‐low‐dose CT scores suggest it may be a useful method of evaluating treatment response. It paralleled improvement in symptoms, circulating inflammatory markers, and changes in the lung microbiota.

Computed tomography and patient risk: Facts, perceptions and uncertainties

Since its introduction in the 1970s, computed tomography (CT) has revolutionized diagnostic decision-making. One of the major concerns associated with the widespread use of CT is the associated increased radiation exposure incurred by patients. The link between ionizing radiation and the subsequent development of neoplasia has been largely based on extrapolating data from studies of survivors of the atomic bombs dropped in Japan in 1945 and on assessments of the increased relative risk of neoplasia in those occupationally exposed to radiation within the nuclear industry. However, the association between exposure to low-dose radiation from diagnostic imaging examinations and oncogenesis remains unclear. With improved technology, significant advances have already been achieved with regards to radiation dose reduction. There are several dose optimization strategies available that may be readily employed including omitting unnecessary images at the ends of acquired series, minimizing the number of phases acquired, and the use of automated exposure control as opposed to fixed tube current techniques. In addition, new image reconstruction techniques that reduce radiation dose have been developed in recent years with promising results. These techniques use iterative reconstruction algorithms to attain diagnostic quality images with reduced image noise at lower radiation doses.

Feasibility of low-dose CT with model-based iterative image reconstruction in follow-up of patients with testicular cancer

Highlights • Radiologists should endeavour to minimise radiation exposure to patients with testicular cancer.• Iterative reconstruction algorithms permit CT imaging at lower radiation doses.• Image quality for reduced-dose CT–MBIR is at least comparable to conventional dose.• No loss of diagnostic accuracy apparent with reduced-dose CT–MBIR.

Plain abdominal radiographs in patients with Crohn's disease: radiological findings and diagnostic value.

AIM To determine the diagnostic yield and clinical value of plain film of the abdomen (PFA) in Crohns disease (CD) patients and to determine whether performance of PFA yields definitive diagnostic information or whether additional imaging examinations are required. MATERIALS AND METHODS One hundred and seventy-seven CD patients underwent 643 PFAs during the period September 1992 to August 2008. Two radiologists blinded to the clinical details independently evaluated individual PFAs and/or their reports for abnormal findings using the following criteria: normal, small bowel (SB) findings; colonic findings, acute CD complications, extra-colonic findings; global assessment/impression. The results of additional imaging studies performed within 5 days of PFA were recorded and findings were analysed. RESULTS A mean of 3.6 (range 1-22) PFAs was performed per patient during the study period. Almost 70% of films were normal (n = 449). SB abnormalities were detected in 21.8% (n = 140) PFAs; most commonly dilated loops (18.8%, n = 121) and mucosal oedema (5%, n = 32). Colonic abnormalities were present in 11.4% (n = 73); most commonly mucosal oedema (7.5%, n = 48) and dilated loops (5%, n = 32). Four cases of pneumoperitoneum were detected. There was no case of toxic megacolon. There was one case in which intra-abdominal abscess/collection was suspected and two cases of obstruction/ileus. Extracolonic findings (renal calculi, sacro-iliitis, etc.) were identified in 7.5% (n = 48). PFAs were followed by additional abdominal imaging within 5 days of PFA in 273/643 (42.5%) of cases. CONCLUSION Despite the high rates of utilization of PFA in CD patients, there is a low incidence of abnormal findings (32.5%). Many of the findings are non-specific and clinically irrelevant and PFA is frequently followed by additional abdominal imaging examinations.

CT Densitometry as a Predictor of Pulmonary Function in Lung Cancer Patients

Purpose: Preoperative pulmonary assessment is undertaken in patients with resectable lung cancer to identify those at increased risk of perioperative complications. Guidelines from the American College of Chest Physicians indicate that if the FEV1 and DLCO are ≥60% of predicted, patients are suitable for resection without further evaluation. The aim of our study is to determine if quantitative measures of lung volume and density obtained from pre-operative CT scans correlate with pulmonary function tests. This may allow us to predict pulmonary function in patients with lung cancer and identify patients who would tolerate surgical resection. Materials and Methods: Patients were identified retrospectively from the lung cancer database of a tertiary hospital. Image segmentation software was utilized to estimate total lung volume, normal lung volume (values -500 HU to -910 HU), emphysematous volume (values less than -910 HU), and mean lung density from pre-operative CT studies for each patient and these values were compared to contemporaneous pulmonary function tests. Results: A total of 77 patients were enrolled. FEV1 was found to correlate significantly with the mean lung density (r=.762, p<.001) and the volume of emphysema (r= -.678, p<.001). DLCO correlated significantly with the mean lung density (r =.648, p<.001) and the volume of emphysematous lung (r= -.535, p<.001). Conclusion: The results of this study suggest that both FEV1 and DLCO correlate significantly with volume of emphysema and mean lung density. We now plan to prospectively compare these CT parameters with measures of good and poor outcome postoperatively to identify CT measures that may predict surgical outcome preoperatively