A multilevel analysis of factors influencing the flow efficiency of the cataract surgery process in hospitals.

PURPOSE: To detect factors contributing to variation in cataract surgery processes. METHODS: A multilevel study was conducted to compare the process of cataract surgery between hospitals in Belgium. The main data were collected through non-participative observations and time measurements in four hospitals. Surgeons (n = 16) performing cataract surgery in the selected region and their patients (n = 274) undergoing cataract surgery were observed. Flow efficiency is measured in the operating room (OR) as time for preparation, surgery, exit and turnover. RESULTS: Flow efficiency in the OR can be negatively influenced by the severity of the cataract [+2.778 (1.139) min in preparation time (p < 0.05); +4.616 (1.786) min in surgery time when severe cataract (p < 0.05)] and the presence of special-cause variation [+2.832 (1.893) min preparation time (p < 0.05); +2.503 (1.277) min surgery time (p < 0.05); +1.181 (0.350) min exit time (p ≤ 0.001)]. Administering topical analgesia instead of peribulbar [+13.548 (4.436) min preparation time (p ≤ 0.001)], retrobulbar [+3.856 (1.548) min surgery time (p ≤ 0.05)] or general analgesia [+5.617 (2.536) min surgery time (p < 0.05); +5.175 (0.817) min exit time (p ≤ 0.001)] enhances flow efficiency. The experience of surgeons (>15 years) impacts flow efficiency [+12.838 (5.922) min surgery time when low experience]. The volume of cataracts performed annually per surgeon did not have a significant impact on flow efficiency. The use of specialized scrub nurses [-7.146 (3.099) min preparation time (p ≤ 0.05); -2.116 (0.586) min turnover time (p ≤ 0.05)] and the eye clinic design [-1.742 (0.686) min exit time (p < 0.05); 2.296 (1.034) min turnover time (p ≤ 0.05)] benefit flow efficiency. CONCLUSION: Controllable and uncontrollable factors with clinical and organizational causes influencing flow efficiency in the cataract process were found. These factors can be taken into account in the management of the healthcare process.

Effects of physician-owned specialized facilities in health care: a systematic review.

BACKGROUND: Multiple studies have investigated physician-owned specialized facilities (specialized hospitals and ambulatory surgery centres). However, the evidence is fragmented and the literature lacks cohesion. OBJECTIVES: To provide a comprehensive overview of the effects of physician-owned specialized facilities by synthesizing the findings of published empirical studies. METHODS: Two reviewers independently researched relevant studies using a standardized search strategy. The Institute of Medicine's quality framework (safe, effective, equitable, efficient, patient-centred, and accessible care) was applied in order to evaluate the performance of such facilities. In addition, the impact on the performance of full-service general hospitals was assessed. RESULTS: Forty-six studies were included in the systematic review. Overall, the quality of the included studies was satisfactory. Our results show that little evidence exists to confirm the advantages attributed to physician-owned specialized facilities, and their impact on full-service general hospitals remains limited. CONCLUSION: Although data is available on a wide variety of effects, the evidence base is surprisingly thin. There is no compelling evidence available demonstrating the added value of physician-owned specialized facilities in terms of quality or cost of the delivered care. More research is necessary on the relative merits of physician-owned specialized facilities. In addition, their corresponding impact on full-service general hospitals remains unclear. The development of physician-owned specialized facilities should thus be monitored carefully.

Correlation of contrast-detail analysis and clinical image quality assessment in chest radiography with a human cadaver study.

PURPOSE: To determine the correlation between the clinical and physical image quality of chest images by using cadavers embalmed with the Thiel technique and a contrast-detail phantom. MATERIALS AND METHODS: The use of human cadavers fulfilled the requirements of the institutional ethics committee. Clinical image quality was assessed by using three human cadavers embalmed with the Thiel technique, which results in excellent preservation of the flexibility and plasticity of organs and tissues. As a result, lungs can be inflated during image acquisition to simulate the pulmonary anatomy seen on a chest radiograph. Both contrast-detail phantom images and chest images of the Thiel-embalmed bodies were acquired with an amorphous silicon flat-panel detector. Tube voltage (70, 81, 90, 100, 113, 125 kVp), copper filtration (0.1, 0.2, 0.3 mm Cu), and exposure settings (200, 280, 400, 560, 800 speed class) were altered to simulate different quality levels. Four experienced radiologists assessed the image quality by using a visual grading analysis (VGA) technique based on European Quality Criteria for Chest Radiology. The phantom images were scored manually and automatically with use of dedicated software, both resulting in an inverse image quality figure (IQF). Spearman rank correlations between inverse IQFs and VGA scores were calculated. RESULTS: A statistically significant correlation (r = 0.80, P < .01) was observed between the VGA scores and the manually obtained inverse IQFs. Comparison of the VGA scores and the automated evaluated phantom images showed an even better correlation (r = 0.92, P < .001). CONCLUSION: The results support the value of contrast-detail phantom analysis for evaluating clinical image quality in chest radiography.

Do hospital physicians' attitudes change during PACS implementation? A cross-sectional acceptance study.

PURPOSE: The purpose of this study is to gain a better insight into the reasons why hospital physicians accept and use a Picture Archiving and Communication System (PACS). Two research questions are put forward, pertaining to (1) factors that contribute to physicians' acceptance of PACS, and (2) whether these factors change as physicians gain experience in using PACS. METHODS: Questionnaires were administered at three moments in time during the PACS implementation process in a private hospital: just before its introduction (T1), four months later (T2), and about fifteen months after the introduction of PACS (T3). The Unified Theory of Acceptance and Use of Technology was chosen as the theoretical framework for this study. Hence, the following scales were measured: performance expectancy, effort expectancy, social influence, facilitating conditions, behavioral intention, and self-reported frequency of use. RESULTS: Forty-six usable responses were obtained at T1, 52 at T2 and 61 at T3. Three variables directly influenced PACS acceptance (measured as behavioral intention and use of PACS): effort expectancy, performance expectancy, and social influence; and their influence evolved over time. Effort expectancy was of particular importance at T1, whereas performance expectancy influenced acceptance at T2 and T3; social influence was the only consistent predictor of PACS acceptance at all times. Variance explained in behavioral intention ranged from .26 at T1 to .58 at T3. CONCLUSIONS: In this setting, the main motivation for physicians to start using PACS is effort expectancy, whereas performance expectancy only becomes important after the physicians started using PACS. It is also very important that physicians perceive that their social environment encourages the use of PACS.

Assessment of tumor vascularization in pancreatic adenocarcinoma using 128-slice perfusion computed tomography imaging.

OBJECTIVE: Computed tomography (CT) perfusion studies can provide valuable information regarding tumor vascularization. We report on a study assessing CT perfusion characteristics in the normal pancreas and in patients with pancreatic adenocarcinoma. METHODS: Twenty healthy subjects and 20 patients with histologically confirmed pancreatic adenocarcinoma were included in the study after written informed consent and approval by our institutional review board. All subjects underwent perfusion CT imaging of the pancreas using 128-slice dual-source CT. The scanning sequence included 18 scans. Parametric maps of blood volume (BV), blood flow (BF), and permeability surface area product (PS) were generated and compared with density measurements. RESULTS: In normal pancreas, no significant difference in perfusion values was observed between head, body, and tail of the pancreas. Mean organ values were 76.76 (SD, 15.6) mL/100 g/min, 15.80 (SD, 2.40) mL/100 g, and 27.74 (SD, 16.8) mL/100 g/min for BF, BV, and PS, respectively. Compared with the normal pancreas, a 60% reduction in BF and BV was observed in the tumor tissue. Perfusion values gradually increased toward the tumor rim. Necrotic tumor areas were identified in 25% of patients. No significant differences were observed when comparing normal pancreas and healthy pancreatic tissue in adenocarcinoma patients. CONCLUSIONS: The feasibility of whole-tumor perfusion imaging using 128-slice CT was demonstrated in patients with pancreatic adenocarcinoma. Perfusion CT provides additional information compared with image assessment based on density measurements (Hounsfield units) and allows noninvasive assessment of vascularization in the tumor tissue.

Assessment of neovascular permeability in a pancreatic tumor model using dynamic contrast-enhanced (DCE) MRI with contrast agents of different molecular weights.

OBJECT: We evaluated the relationship of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)-derived pharmacokinetic parameters and contrast agents with different molecular weights (MW) in a pancreatic tumor mouse model. MATERIALS AND METHODS: Panc02 tumors were induced in mice at the hind leg. DCE-MRI was performed using Gadolinium (Gd)-based contrast agents with different MW: Gd-DOTA (0.5 kDa), P846 (3.5 kDa), and P792 (6.47 kDa). Quantitative vascular parameters (AUC, K(trans), V(e), and V(p)) were calculated according to a modified Tofts two-compartment model. Values for all contrast groups were compared for tumor and control (muscle) tissues. RESULTS: Values for K(trans) and V(e) were significantly higher in tumor tissue than in muscle tissue. When comparing contrast agents, lowest absolute K(trans) values were observed using P792. The relative increase in K(trans) in tumor tissue compared with normal tissue was highest after the use of P792. In both tumor and normal tissues, K(trans) decreased with increasing molecular weight of the contrast agent used. CONCLUSION: It was demonstrated that values for the different DCE-MRI vascular (permeability) parameters are highly dependent on the contrast agent used. Due to their potential to better differentiate tumor from muscle tissue, higher molecular weight contrast agents show promise when evaluating tumors using DCE-MRI.

Noninvasive monitoring of therapy-induced microvascular changes in a pancreatic cancer model using dynamic contrast-enhanced magnetic resonance imaging with P846, a new low-diffusible gadolinium-based contrast agent.

A predictive technique in the management of patients with cancer could improve the therapeutic index by allowing better individualization of treatment. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive technique that can provide anatomical and physiological information on the tumor and its microenvironment. We studied the effect of chemotherapy (gemcitabine), anti-angiogenesis therapy (sunitinib) and radiotherapy on the kinetics of DCE-MRI parameters in a preclinical model of pancreatic cancer using P846, a new low-diffusible contrast agent. Mice underwent DCE-MRI before treatment (MRI1), after 1 week of treatment (MRI2), and after 1 additional week (MRI3). Combined treatment with radiotherapy and sunitinib had a synergistic effect on tumor growth. In radiotherapy/sunitinib-treated mice, a decrease in K(trans) at MRI2 predicted its superior antivascular and antitumor effect at an early time. An increased K(trans) at MRI2, as seen in gemcitabine- and gemcitabine/sunitinib-treated mice, reflects increased permeability for P846 and might predict a smaller therapeutic effect at this early time. This study shows that the kinetics of DCE-MRI parameters depends on the contrast agent used. P846 appears to be a promising low-diffusible agent to monitor therapeutic effects in this preclinical cancer model, but further studies are needed to compare its behavior with Gd-DTPA and macromolecular-weight contrast agents. Sunitinib as a radiosensitizer is promising for future clinical trials in human pancreatic cancer.

How do referring clinicians want radiologists to report? Suggestions from the COVER survey.

OBJECTIVE: To investigate what referring clinicians suggest when asked how the quality of radiology reports can be improved. METHODS: At the end of the questionnaire of the COVER survey, a bi-national quantitative survey on the radiology report among referring physicians, clinical specialists and general practitioners were able to freely enter suggestions with regard to improving the quality of the report. These suggestions were isolated from the quantitative results. Subjects and themes were identified, examined, ordered, counted, compared and analysed. RESULTS: Of a total of 3,884 invitations to participate, we received 735 response forms from clinicians (18.9%), 233 (31.7%) of which contained suggestions. Issues mentioned most frequently were the need for clinical information and a clinical question, for a conclusion, structuring, communicating directly with the clinician, completeness, integrating images or referring to images, mentioning relevant findings outside of the clinical question, mentioning a diagnosis or suitable differential diagnosis, and concise reporting. CONCLUSION: Although these spontaneous suggestions are erratic and sometimes contradictory, they summarise the ideas as well as the emotions of these clients of the radiology department. Therefore it is advisable to take them into account when developing new ways of reporting.

Variability of CT contrast enhancement in the pancreas: a cause for concern?

BACKGROUND: Multidetector CT is a valuable technique for diagnosis/staging in several pancreatic pathologies. Diagnosis is usually based on tissue density measurements. Recently, newer functional CT techniques have been introduced. The aim of this study was to assess variability in perfusion and dual-energy CT data, and to compare these data with density measurements in the pancreas of a healthy population. METHODS: Two groups were included: 20 patients underwent perfusion CT imaging, and 10 patients were scanned using a dual-energy protocol. In both groups, tissue density [Hounsfield units (HU)] was measured in the pancreatic head, body and tail. Functional data were calculated (blood flow/blood volume in the perfusion CT group, iodine concentration in the dual-energy group), and variability was assessed. RESULTS: Density measurements were comparable for the perfusion and dual-energy CT groups, and ranged from 14 to 60 HU. Maximal enhancement differences between the head/body/tail of the pancreas ranged between 2 and 21 HU. Considerable variability was observed, both in density measurements (ranging from 3 to 34%) and in functional parameters (mean variability in perfusion CT parameters blood flow and blood volume was 21.3 and 10% respectively; mean variability in dual-energy iodine-mapping results was 24.4%). CONCLUSION: This study demonstrated the presence of important intraindividual variability in pancreatic tissue contrast enhancement, regardless of the CT technique used. Considering the variability observed in this study, the use of cut-off values to characterize pancreatic pathologies seems troublesome, and morphologic primary and secondary changes will remain important, even when using novel functional imaging techniques. and IAP.

Acute pancreatitis: radiologic scores in predicting severity and outcome.

Acute pancreatitis (AP) is a common inflammatory disease which can be mild and self-limiting without complications or severe with prolonged hospitalization, high morbidity, and high mortality. Different radiological scoring systems to predict severity and outcome in AP have been developed since the early 1990s. In the meantime, new insights in the pathophysiology of AP and consequently, therapeutic management of these patients have been introduced. The purpose of this review is therefore (1) to describe the current terminology and new concepts in the pathophysiology, (2) to outline the long existing and newly developed radiological scoring systems in prediction of severity and outcome with their respective advantages and limitations, and (3) to define the role of radiological prognostic scoring systems in the new environment of perception of the last decade. Risk stratification in AP requires scoring systems that can be calculated early in the course of disease which allows time for intervention. For that reason, scoring systems based on necrosis are not useful in severity prediction. The recent developed radiological scoring systems based on signs of systemic inflammatory response syndrome and organ dysfunction are promising in prediction of severity early after onset of AP.

Monitoring the PACS implementation process in a large university hospital--discrepancies between radiologists and physicians.

Successfully introducing a new technology in a health-care setting is not a walk in the park. Many barriers need to be overcome, not only technical and financial but also human barriers. In this study, we focus on the human barriers to health-care information systems' implementation. We monitored the acceptance of a Picture Archiving and Communication System (PACS) by radiologists and hospital physicians in a large Belgian university hospital. Hereto, questionnaires were taken pre-implementation (T1) and 1 year after the radiology department stopped printing film (T2). The framework we used to perform the study was the Unified Theory of Acceptance and Use of Technology. Main findings were that both groups were positive toward PACS prior to the introduction and that each group was even more positive at T2 with extensive PACS experience. In general, the ratings of the radiologists were higher than those of the physicians, as the radiologists experienced more of the benefits of PACS and had to use PACS throughout the day. Two factors were salient for predicting users' intention to use PACS: the usefulness of PACS (performance expectancy) and the availability of support of any kind (facilitating conditions). The results show that our approach was successful. Both radiologists and physicians give evidence of an excellent level of user acceptance. We can conclude that the implementation of PACS into our hospital has succeeded.

Extrapancreatic inflammation on abdominal computed tomography as an early predictor of disease severity in acute pancreatitis: evaluation of a new scoring system.

OBJECTIVE: To introduce a new scoring system based on signs of systemic inflammation on computed tomography (CT) [ExtraPancreatic Inflammation on CT (EPIC) score] and evaluate this score as an early prognostic tool. METHODS: Forty patients with acute pancreatitis who received an abdominal CT within 24 h after admission were included in the study. The Balthazar score, the CT Severity Index, and the EPIC score (based on the presence of pleural effusion, ascites, and retroperitoneal fluid collections) were calculated for all patients. The end points were the occurrence of severe acute pancreatitis (local complication or presence of organ failure for more than 48 h) and in hospital mortality. This score was evaluated by calculating receiver operator characteristic (ROC) curves and the area under the ROC curve. RESULTS: Mean age of the patients was 50 (+/-17.7) years, and Ranson score was 3.3. Fourteen (35%) patients developed severe disease; in hospital mortality was 15% (6/40). The mean EPIC score was 3.6 (+/-2.0). The area under the ROC curve for predicting severe disease and mortality was 0.91 (95% confidence interval, 0.83-0.99) and 0.85 (95% confidence interval, 0.71-0.99), respectively. An EPIC score of 4 or more had a 100% sensitivity and 70.8% specificity for predicting severe pancreatitis. The EPIC score was superior to the Balthazar score and CT Severity Index to predict outcome. CONCLUSIONS: In patients with acute pancreatitis, extrapancreatic inflammation assessed by abdominal CT scan and quantified with the EPIC score allows accurate estimation of disease severity and mortality within 24 h of admission.

Is combined 18F-fluorodeoxyglucose-positron emission tomography/computed tomography superior to positron emission tomography or computed tomography alone for diagnosis, staging and restaging of pancreatic lesions?

BACKGROUND AND STUDY AIMS: To evaluate whether combined 18F-FDG PET/CT has an additive value over 18F-FDG-PET or CT alone for diagnosis, staging and restaging of pancreatic lesions. PATIENTS AND METHODS: Forty-six consecutive patients (23 women, 23 men; median age 62.5 years) underwent FDG-PET/CT. Analysis of PET, CT and fused PET/CT images was performed by 2 readers. Patients were divided into 2 groups: diagnosis and staging of primary tumours (n=34) and restaging: screening for recurrent or progressive pancreatic cancer (n=12). Accuracy analysis was performed lesion-by-lesion and patient-by-patient. Results were correlated with histopathology or clinical follow-up. RESULTS: Ninety-five foci were identified on PET, 140 lesions on CT and 119 on PET/CT. Thirty-four lesions were defined as 'definitely pathologic' and localised in pancreas, liver, lung or bone by all 3 techniques with equal certainty. In 11 patients malignancy was ruled out with the highest certainty by PET/CT. All 3 modalities made 2 false positive diagnoses of malignancy and missed metastases or vascular ingrowth in 7 patients. The accuracy rate of PET/CT (91.2%) for diagnosis of primary pancreatic lesions is higher compared to CT (88.2%) and PET alone (82.3%). Also for locoregional staging PET/CT has a higher accuracy rate (85.3%) compared to CT (83.8%) and PET (79.4%). When used for restaging, sensitivity (90.0%) and accuracy rate (91.6%) were highest for PET and PET/CT. CT had a lower sensitivity (80.0%). CONCLUSIONS: Topographical assignment of 'spots' with high FDG uptake is superior with PET/CT compared to PET alone. Fused PET/CT has a slightly higher sensitivity and accuracy rate for diagnosis and locoregional staging of primary pancreatic lesions compared to CT alone. PET and PET/CT perform equally well in screening for recurrent or progressive pancreatic cancer, with high accuracy. Due to its unlimited access, lower radiation exposure and cost, multidetector row CT remains the imaging technique of choice for diagnosis, staging and screening for recurrent pancreatic cancer.

Image quality and radiation dose on digital chest imaging: comparison of amorphous silicon and amorphous selenium flat-panel systems.

OBJECTIVE: The aim of this study was to compare the image quality and radiation dose in chest imaging using an amorphous silicon flat-panel detector system and an amorphous selenium flat-panel detector system. In addition, the low-contrast performance of both systems with standard and low radiation doses was compared. MATERIALS AND METHODS: In two groups of 100 patients each, digital chest radiographs were acquired with either an amorphous silicon or an amorphous selenium flat-panel system. The effective dose of the examination was measured using thermoluminescent dosimeters placed in an anthropomorphic Rando phantom. The image quality of the digital chest radiographs was assessed by five experienced radiologists using the European Guidelines on Quality Criteria for Diagnostic Radiographic Images. In addition, a contrast-detail phantom study was set up to assess the low-contrast performance of both systems at different radiation dose levels. Differences between the two groups were tested for significance using the two-tailed Mann-Whitney test. RESULTS: The amorphous silicon flat-panel system allowed an important and significant reduction in effective dose in comparison with the amorphous selenium flat-panel system (p < 0.0001) for both the posteroanterior and lateral views. In addition, clinical image quality analysis showed that the dose reduction was not detrimental to image quality. Compared with the amorphous selenium flat-panel detector system, the amorphous silicon flat-panel detector system performed significantly better in the low-contrast phantom study, with phantom entrance dose values of up to 135 muGy. CONCLUSION: Chest radiographs can be acquired with a significantly lower patient radiation dose using an amorphous silicon flat-panel system than using an amorphous selenium flat-panel system, thereby producing images that are equal or even superior in quality to those of the amorphous selenium flat-panel detector system.

Image quality performance of liquid crystal display systems: influence of display resolution, magnification and window settings on contrast-detail detection.

The aim of this study was to investigate the combined effects of liquid crystal display (LCD) resolution, image magnification and window/level adjustment on the low-contrast performance in soft-copy image interpretation in digital radiography and digital mammography. In addition, the effect of a new LCD noise reduction mechanism on the low-contrast detectability was studied. Digital radiographs and mammograms of two dedicated contrast-detail phantoms (CDRAD 2.0 and CDMAM 3.4) were scored on five LCD devices with varying resolutions (1-3- and 5-megapixel) and one dedicated 5-megapixel cathode ray tube monitor. Two 5-megapixel LCDs were included. The first one was a standard 5-megapixel LCD and the second had a new (Per Pixel Uniformity) noise reduction mechanism. A multi-variate analysis of variance revealed a significant influence of LCD resolution, image magnification and window/level adjustment on the image quality performance assessed with both the CDRAD 2.0 and the CDMAM 3.4 phantoms. The interactive adjustment of brightness and contrast of digital images did not affect the reading time, whereas magnification to full resolution resulted in a significantly slower soft-copy interpretation. For digital radiography applications, a 3-megapixel LCD is comparable with a 5-megapixel CRT monitor in terms of low-contrast performance as well as in reading time. The use of a 2-megapixel LCD is only warranted when radiographs are analysed in full resolution and when using the interactive window/level adjustment. In digital mammography, a 5-megapixel monitor should be the first choice. In addition, the new PPU noise reduction system in the 5-megapixel LCD devices provides significantly better results for mammography reading as compared to a standard 5-magapixel LCD or CRT. If a 3-megapixel LCD is used in mammography setting, a very time-consuming magnification of the digital mammograms would be necessary.