64-Slice spiral computed tomography of the coronary arteries: dose reduction using an optimized imaging protocol including individual weight-adaptation of voltage and current-time product.

Radiation dose and image quality were compared between a standard protocol (40 patients, group A) and a weight-adapted protocol of voltage and current-time product (44 patients, group B) using 64-slice coronary multidetector computed tomography (MDCT). Effective dose estimate was lower by 37% in all patients of group B (9.2 +/- 2.5 mSv) compared with group A (14.6 +/- 2.3 mSv, P < 0.0001). Group B patients with a small body mass index (BMI) benefited most with a dose reduction of 53% (6.7 +/- 1.5 mSv in group B versus 14.1 +/- 1.8 mSv in group A, P < 0.0001). Moderate reductions of 32% and 20% were achieved for patients with a medium and large BMI, respectively. Reduction in radiation dose did not affect the image quality as assessed by image noise, signal-to-noise ratios, and number of coronary segments with good diagnostic image quality. Individual weight-adaptation of voltage and current-time product significantly reduces the radiation dose without loss of image quality.

Myocardial contractile response to increasing doses of dobutamine in patients with reperfused acute myocardial infarction by cardiac magnetic resonance imaging.

BACKGROUND: Cardiac magnetic resonance imaging uses contractile response to dobutamine (DCMR) and delayed contrast enhancement (DE) to assess myocardial viability. However, early after acute myocardial infarction (AMI) the optimal dose of dobutamine is unclear. METHODS: In patients early after reperfused AMI, DCMR at 5, 10 and 20 microg*kg(-1)*min(-1) and measurement of DE was performed. On three short-axis slices 18 segments were graded as no DE, DE <50% and DE >or=50%. Thickening (systolic-diastolic wall thickness) and contractile reserve (max. thickening - rest) were determined. Segments were classified dysfunctional if thickening was >2 SD below normal or <2 mm. RESULTS: Forty-nine patients participated. In segments with no DE, thickening increased continuously but contractile reserve was low (0.9 +/- 3.2 mm) and dysfunctional segments were unchanged (rest: 13.1% vs. 20 microg: 14.8%). In segments with DE, contractile reserve was high (1.4 +/- 3.0 mm and 1.5 +/- 3.0 mm) and dysfunctional segments decreased from rest to 20 microg (50 vs. 24.8% and 79.9 vs. 43.2%). Between 5 and 10 microg no change of thickening and of dysfunctional segments occurred. CONCLUSION: Early after AMI, DCMR demonstrated no diagnostic benefit in segments with no DE. In segments with DE, higher dose of dobutamine can provide additional information on contractile reserve and dysfunctional segments.

The fate of osteochondral grafts after autologous osteochondral transplantation: a one-year follow-up study in a minipig model.

INTRODUCTION: Because articular cartilage shows little intrinsic capacity of spontaneous regeneration, a variety of treatment options are currently at use to repair cartilage damage. One of these is the autologous osteochondral transplantation (AOT). The aim of the present work was to study the histological changes during the progress of 1 year after AOT in the knee joint. MATERIALS AND METHODS: Twelve Minipigs underwent an AOT on the medial femoral condyles of both knees using cooled diamond studded trephines with a diameter of the grafts of 4.6 mm. Three animals were sacrificed at each 2, 8, 26 and 52 weeks after the operation. The condyles were analyzed histologically and immunohistologically for collagen types I and II. RESULTS: A successful bony incorporation was observed in all specimens. The transplant demonstrated an increasingly stable integration of the chondral matrix into the cartilage of the surrounding femoral condyle. At 52 weeks after the operations 5 of 6 condyles showed a chondral integration at least at one side of the graft. Immunohistologically all specimens showed physiological staining characteristics up to 52 weeks after operation. The quality of the chondral part of the graft showed a wide range of variations, ranging from vital tissue resembling native cartilage after 52 weeks, to severe degenerative signs beginning 2 weeks after operation and ending at 52 weeks with deep fissures fragmenting the cartilage and the complete loss of vital cells. CONCLUSION: The press-fit technique allows a stable bony incorporation. A chondral integration of the graft seems to occur, provided that a close contact between the interfaces can be achieved. Present results demonstrate a vital cartilagenous transplant for up to 52 weeks. However, some specimens showed in part severe degenerative signs. A possible explanation is an insufficient cooling of the trephines in relation to the small diameter of the grafts used in the minipig model. The collagen network seems not to be affected for up to 52 weeks.

MRI of the coronary vessel wall at 3 T: comparison of radial and cartesian k-space sampling.

OBJECTIVE: The purpose of our study was to compare the quality of 3D gradient-echo images obtained using radial versus cartesian k-space sampling at 3 T. CONCLUSION: This study shows that the quality of coronary vessel wall imaging of the right coronary artery with radial k-space sampling in 3D turbo field-echo sequences is superior to cartesian k-space sampling at 3 T. Radial k-space sampling at 3 T makes it possible to combine low motion artifact susceptibility with high signal-to-noise ratio.

Comparison of the Detection Rate of Simulated Microcalcifications in Full-Field Digital Mammography, Digital Breast Tomosynthesis, and Synthetically Reconstructed 2-Dimensional Images Performed With 2 Different Digital X-ray Mammography Systems.

OBJECTIVE: The aim of this study was to compare the microcalcification detectability in an anthropomorphic phantom model regarding number, size, and shape in full-field digital mammography (FFDM), synthetically reconstructed 2-dimensional (Synthetic-2D) images, and digital breast tomosynthesis (DBT) performed with 2 different x-ray mammography systems. MATERIALS AND METHODS: Simulated microcalcifications of different numbers (0 to >39), sizes (diameter, 100-800 µm), and shapes (round vs heterogeneous) were scattered by random distribution on 50 film phantoms each divided in 4 quadrants. The FFDM and DBT x-rays were taken from each of these 50 films with both x-ray mammography systems (SenoClaire; GE Healthcare, Selenia Dimensions, Hologic) using an anthropomorphic scattering body and automatic exposure control. The resulting exposure factors were similar to a clinical setting. The synthetically reconstructed 2D images were generated automatically on both systems. All FFDM, Synthetic-2D, and DBT images were interpreted in randomized order and independently of each other by 6 radiologists using a structured questionnaire. RESULTS: The number categories of simulated microcalcifications were correctly evaluated in 55.3% of instances (quadrant by reader) in FFDM, 50.9% in the Synthetic-2D views, and 59.5% in DBT, summarized for 200 quadrants per reader for each Device A and B, respectively. Full-field digital mammography was superior to Synthetic-2D (mean difference, 4%; 95% confidence interval [CI], 2%-7%; P < 0.001), and DBT was superior to both FFDM (mean difference, 4%; 95% CI, 2%-7%; P = 0.002) and Synthetic-2D (mean difference, 9%; 95% CI, 6%-11%; P < 0.001). This trend was consistent in all subgroup analyses. The number of the smallest microcalcifications (100-399 µm) was correctly evaluated in 25.2% of the FFDM, in 14.2% for Synthetic-2D, and in 28.3% of the DBT images. Underestimations of the number of simulated microcalcifications were more common than overestimations. Regarding the size categories of simulated microcalcifications, the rates of correct assessments were in 45.4% of instances in FFDM, 39.9% in the Synthetic-2D views, and 43.6% in DBT, summarized for 200 quadrants per reader and both imaging devices. CONCLUSIONS: In the presented in vitro environment using an anthropomorphic phantom model, standard full-field digital x-ray mammography was superior to synthetically reconstructed 2-dimensional images in the detection of simulated microcalcifications. In view of these results, it is questionable whether Synthetic-2D images can replace FFDM in clinical examinations at the present time. Further investigations are needed to assess the clinical impact of the in vitro results.

Inhibition of xanthine oxidase improves myocardial contractility in patients with ischemic cardiomyopathy.

Reactive oxygen species, in particular superoxide, have been closely linked to the underlying pathophysiology of ischemic cardiomyopathy: superoxide not only mediates mechanoenergetic uncoupling of the myocyte but also adversely impacts on myocardial perfusion by depleting endothelial-derived nitric oxide bioavailability. Xanthine oxidase generates superoxide upon oxidation of hypoxanthine and xanthine and has been detected in cardiac myocytes and coronary endothelial cells of patients with ischemic heart disease. Here we investigated the effects of oxypurinol, a xanthine oxidase inhibitor, on myocardial contractility in patients with ischemic cardiomyopathy. Twenty patients (19 males, 66+/-8 years) with stable coronary disease, severely suppressed systolic function (left ventricular ejection fraction 22+/-2%), and nonelevated uric acid plasma levels received a single intravenous dose of oxypurinol (400 mg). Cardiac MRI studies, performed before and 5.2+/-0.9 h after oxypurinol administration, revealed a reduction in end-systolic volumes (-9.7+/-4.2%; p=0.03) and an increase in left ventricular ejection fraction (+17.5+/-5.2%; p=0.003), whereas 6 patients (6 males, 63+/-3.8 years, ejection fraction 26+/-5%) who received vehicle only did not show significant changes in any of the parameters studied. Oxypurinol improves left ventricular function in patients with ischemic cardiomyopathy. These results underscore the significance of reactive oxygen species as important pathophysiological mediators in ischemic heart failure and point toward xanthine oxidase as an important source of reactive species that serve to modulate the myocardial redox state in this disease.

A practical insulin infusion algorithm for the establishment of euglycaemia in both lean and obese patients with type 1 and type 2 diabetes.

BACKGROUND: Both in research and in various clinical situations, prolonged euglycaemia can be desirable. In recent years, its benefit in (critically) ill patients and patients with acute myocardial infarction has been established. The objective of this study was to assess safety and efficacy of a practical, bodyweight-dependent algorithm to establish euglycaemia in both lean and obese patients with type 1 and type 2 diabetes. METHODS: In 43 patients with type 1 diabetes and 17 patients with type 2 diabetes insulin were infused overnight to establish euglycaemia. Plasma glucose concentration was determined at 45 min intervals, and the insulin infusion rate was altered according to the algorithm. RESULTS: Baseline plasma glucose concentrations were 13.1+/- 4.4 and 12.7 +/- 4.0 mmol/l in type 1 and type 2 diabetic patients, respectively. In both groups mean plasma glucose was reduced below 8.0 mmol/l within 3 h, and averaged 7.4 +/- 1.4 and 7.2 +/- 1.0 mmol/l (P = 0.11) over the next 7 h. Five (11.6%) patients with type 1 diabetes required administration of glucose because plasma glucose concentrations fell below 4.4 mmol/l. Consequently, type 1 diabetic patients were hypoglycaemic during 0.89% of the total study period. The lowest plasma glucose recorded was 3.9 mmol/l. In the type 2 diabetic patients the lowest plasma glucose was 5.5 mmol/l and no glucose administration was required for near-hypoglycaemia. The algorithm was equally effective in both lean and obese patients. CONCLUSIONS: Euglycaemia was established simply, swiftly and safely during the study period with the practical weight-based algorithm used in this study, in both lean and obese type 1 and type 2 diabetic patients, with a very low rate of mild hypoglycaemia. The algorithm is applicable in research and various several clinical settings. Its validity for a prolonged period of time and in critically ill patients needs to be further evaluated.

Comparison of the accuracy of the HemoCue glucose analyzer with the Yellow Springs Instrument glucose oxidase analyzer, particularly in hypoglycemia.

OBJECTIVE: We aimed to assess the accuracy of the HemoCue Beta-glucose analyzer (HemoCue) and its correlation with the Yellow Springs Instrument (YSI 2300 STAT; YSI) glucose oxidase analyzer, in particular for hypoglycemic values. DESIGN AND METHODS: Samples were taken from 24 volunteers during hyperinsulinemic glucose clamp studies. Glucose concentrations were determined immediately with the HemoCue in whole blood and with the YSI in plasma from the same sample. After correction for the difference between whole blood and plasma, the paired plasma glucose concentrations were analyzed with various statistical methods. RESULTS: A total of 500 paired glucose values were obtained, 209 of which were in the hypoglycemic range. Mean+/-s.e. values were 4.85+/-0.004 mmol/l for the HemoCue (range 1.87-16.17) and 4.81+/-0.004 mmol/l for the YSI (range 1.88-15.00; P = 0.80). In the hypoglycemic region, values were 3.26+/-0.004 mmol/l for the HemoCue (range 1.87-5.17) and 3.22+/-0.003 mmol/l for the YSI (range 1.88-4.20; P = 0.59). Regression analyses were HemoCue = 1.019(YSI) -0.0577 mmol/l, with r = 0.9787 for all values; for hypoglycemic values the HemoCue = 1.1169(YSI) -0.3393 mmol/l, with r = 0.8798. Using Altman's residual plot, the difference was 0.03+/-0.0009 mmol/l, with 18 (3.6%) paired values outside the 95% limits of agreement (-0.82 to 0.89 mmol/l). In the hypoglycemic range, the difference was 0.04+/-0.001 mmol/l, with six (2.9%) values outside the 95% limits of agreement (-0.71 to 0.79 mmol/l). In error grid analysis, one value was in zone D (0.2%) and five values (1%) were in zone B; 98.8% were within zone A. CONCLUSIONS: Determination of glucose with the HemoCue system had very good correlation with the YSI system in a broad range of glycemia and also for hypoglycemic values. We believe that these methods can be used interchangeably for research and clinical purposes in adults.

Multislice computed tomography-urography: intraindividual comparison of different preparation techniques for optimized depiction of the upper urinary tract in an animal model.

OBJECTIVES: We sought to evaluate intraindividually 3 different preparation protocols for achieving improved opacification and anatomic depiction of the upper urinary tract in multisclice computed tomography urography (MSCTU) using a porcine model. MATERIAL AND METHODS: MSCTU was performed in 8 healthy pigs. Each animal underwent 3 MSCT urographies using 3 different preparations before the injection of contrast material: A, intravenous (iv) saline (250 mL); B, iv low-dose furosemide (0.1 mg/kg); and C, iv saline (250 mL) plus iv low-dose furosemide (0.1 mg/kg). Image analysis was performed blinded to the applied protocols and included the evaluation of the opacification and anatomic depiction of the upper urinary tract by means of graded scales. Ureteral distension was determined and density was measured within the collecting system. RESULTS: Furosemide significantly improved both mean opacification scores and mean scores of anatomic depiction compared with the exclusive infusion of saline for MSCTU. There was no significant difference between the application of furosemide and the combination of furosemide plus saline. A significant increase of 25-26% for ureteral distension was found when furosemide was applied. Significant lower mean attenuation values (Hounsfield units) and standard deviation were found within the opacified urine for diuretic-enhanced MSCTU. CONCLUSIONS: Low-dose furosemide injection is superior to saline infusion for achieving optimal enhancement in MSCTU. It is not necessary to combine furosemide and saline infusion. In MSCTU, low-dose furosemide is a simple add-on simplifying image acquisition timing and removing the need for abdominal compression devices.

MR imaging of post-traumatic articular cartilage injuries confined to the femoral trochlea. Arthroscopic correlation and clinical significance.

OBJECTIVE: To assess and describe post-traumatic articular cartilage injuries isolated to the trochlear groove and provide insight into potential mechanism of injury. MATERIALS AND METHODS: We retrospectively evaluated MR imaging findings of all knee MRIs performed at our institution over the last 2 years (2450). Thirty patients met the criteria of a cartilage injury confined to the trochlear groove. In 15 cases, which were included in our study, arthroscopic correlation was available. Each plane was evaluated and graded for the presence and appearance of articular cartilage defects using a standard arthroscopic grading scheme adapted to MR imaging. Any additional pathological derangement was documented and information about the mechanism of injury was retrieved by chart review. RESULTS: In all cases the cartilaginous injury was well demonstrated on MRI. In 13 patients additional pathological findings could be observed. The most frequently associated injury was a meniscal tear in nine patients. In eight cases, the arthroscopic grading of the trochlear injury matched exactly with the MRI findings. In the remaining seven cases, the discrepancy between MRI and arthroscopy was never higher than one grade. In 13 out of 15 of patients trauma mechanism could be evaluated. Twelve patients suffered an indirect twisting injury and one suffered a direct trauma to their knee. CONCLUSION: The findings of this study demonstrate that MR imaging allows reliable grading of isolated injury to the trochlear groove cartilage and assists in directing surgical diagnosis and treatment. These injuries may be the only hyaline cartilage injury in the knee and meniscal tears are a frequently associated finding. Therefore, it is important to search specifically for cartilage injuries of the trochlear groove in patients with anterior knee pain, even if other coexistent pathology could potentially explain the patient's symptoms.

Reducing CT radiation dose with iterative reconstruction algorithms: the influence of scan and reconstruction parameters on image quality and CTDIvol.

OBJECTIVES: In this phantom CT study, we investigated whether images reconstructed using filtered back projection (FBP) and iterative reconstruction (IR) with reduced tube voltage and current have equivalent quality. We evaluated the effects of different acquisition and reconstruction parameter settings on image quality and radiation doses. Additionally, patient CT studies were evaluated to confirm our phantom results. METHODS: Helical and axial 256 multi-slice computed tomography scans of the phantom (Catphan(®)) were performed with varying tube voltages (80-140kV) and currents (30-200mAs). 198 phantom data sets were reconstructed applying FBP and IR with increasing iterations, and soft and sharp kernels. Further, 25 chest and abdomen CT scans, performed with high and low exposure per patient, were reconstructed with IR and FBP. Two independent observers evaluated image quality and radiation doses of both phantom and patient scans. RESULTS: In phantom scans, noise reduction was significantly improved using IR with increasing iterations, independent from tissue, scan-mode, tube-voltage, current, and kernel. IR did not affect high-contrast resolution. Low-contrast resolution was also not negatively affected, but improved in scans with doses <5mGy, although object detectability generally decreased with the lowering of exposure. At comparable image quality levels, CTDIvol was reduced by 26-50% using IR. In patients, applying IR vs. FBP resulted in good to excellent image quality, while tube voltage and current settings could be significantly decreased. CONCLUSIONS: Our phantom experiments demonstrate that image quality levels of FBP reconstructions can also be achieved at lower tube voltages and tube currents when applying IR. Our findings could be confirmed in patients revealing the potential of IR to significantly reduce CT radiation doses.

Identifying experiential expertise to support people with diabetes mellitus in applying for and participating effectively in paid work: a qualitative study.

OBJECTIVE: Identifying and describing successful diabetes-related (SDR) behaviors from reports by experiential experts to support people with diabetes in applying for and participating effectively in paid work. METHODS: Data were collected by conducting in-depth interviews with experiential experts with diabetes (N = 47). RESULTS: A comprehensive set of SDR behaviors that can help people with diabetes apply for and participate in paid work. The most important factors were reported to be the ability to anticipate problems in job applications, effective self-management activities to prevent and/or respond to hypoglycemia and hyperglycemia at work, informing relevant others in the workplace, and successfully negotiating with employers about adjustments to work conditions. CONCLUSIONS: A set of work-related SDR behaviors was identified. After validation by experiential experts and professionals, these could be translated into recommendations and tested in experiments in self-management programs.

Harvesting experiential expertise to support safe driving for people with diabetes mellitus: a qualitative study evaluated by peers in a survey.

BACKGROUND: Hypoglycemia is a frequent phenomenon in people being treated for diabetes mellitus, which can acutely disrupt driving performance. For the benefit of personal and public traffic safety, we decided to identify successful diabetes-related (SDR) behaviors to support safe driving for people with diabetes, from the perspective of experiential experts with diabetes mellitus. Experiential experts are people who can manage their own illness and conditions by developing expertise relevant to maintaining health and countering illness, and who are able to use this expertise to the benefit of peers. OBJECTIVE: The aim of our study was to objectify and systematize experiential expertise in terms of SDR behaviors, based on reports by experiential experts, to support safe driving for people with type 1 and type 2 diabetes mellitus. The emphasis was on preventing hypoglycemia as a short-term complication during driving. METHODS: We performed a mixed-methods study involving (i) semi-structured in-depth interviews with 33 experiential experts with diabetes mellitus from the Dutch Diabetes Association (DVN; Diabetesvereniging Nederland), in order to identify SDR behaviors regarding safe driving, and (ii) a validation study by means of a survey among a panel of 98 experiential experts (peers) from the DVN, to determine the extent to which they agreed with the communicability, importance, and feasibility of these behaviors for drivers with diabetes mellitus. RESULTS: We identified a comprehensive set of 11 SDR behaviors, differentiated into seven general and four specific behaviors, to support safe driving. The general behaviors concern the following topics: (i) acquiring knowledge and information; (ii) acquiring and using self-measuring of blood glucose (SMBG) equipment; (iii) knowing one's physical response pattern; (iv) obtaining knowledge about the medication used; (v) preventing long-term eye complications; (vi) influencing factors that can affect blood glucose; and (vii) renewal procedure for driving license. The four specific behaviors refer to the following topics: (i) measures to be taken before driving; (ii) responding effectively to hypoglycemia while driving; (iii) informing and instructing passengers; and (iv) preventing hypoglycemia in drivers with type 2 diabetes mellitus not using SMBG equipment. Key factors for safe driving proved to be the ability of drivers to anticipate and respond effectively to hypoglycemia while driving and to inform and instruct fellow passengers. Participants of the validation survey agreed to a considerable degree with the communicability, importance, and feasibility of these behaviors to support safe driving for people with diabetes mellitus. CONCLUSIONS: This study resulted in the identification and description of SDR behaviors to support safe driving. It proved possible to operationalize experiential expertise in terms of such behaviors. The next step is to have these behaviors validated by professional care providers in the field of diabetes, followed by translation into recommendations in self-management programs.

Supporting people with diabetes mellitus in applying for and participating effectively in paid work: validation of successful diabetes-related behaviors by experiential experts and professional care providers.

OBJECTIVE: To validate successful diabetes-related behaviors, proposed by a group of experiential experts, and to support people with diabetes in applying for and participating effectively in work. METHODS: In a survey among 77 experiential experts and 21 professional care providers, the behaviors were critically appraised regarding several key characteristics. RESULTS: Experiential experts (median scores: 91%, 86%, and 86%) and professionals (median scores: 76%, 76%, and 81%) mostly agreed with these behaviors in terms of clarity, content, and relevance, respectively. Feasibility was seen as somewhat problematic, with median scores by experiential experts and professionals of 65% and 52%, respectively. CONCLUSION: Both groups confirmed the validity of the proposed work-related behaviors that were expected to support people with diabetes. The challenge is to implement these behaviors in practice, by effective dissemination and incorporation in work-related self-management programs.

[Hypoglycaemia unawareness: judge driving ability prudently]. / Hypoglycemia unawareness: oordeel bewust over rijvaardigheid.

Several factors can influence the ability to drive by patients with diabetes mellitus. The most important factor would be hypoglycaemia. It seems logical that hypoglycaemia unawareness would be an important risk factor for accidents. However, in everyday practice, hypoglycaemia-related accidents are rare. Moreover, it seems that only a small subset of people with diabetes is responsible for the overall slightly elevated risk of car accidents. It appears that not hypoglycaemia unawareness itself is a risk factor, but primarily a history of previous hypoglycaemia-related accidents. Although ascertaining hypoglycaemia awareness currently seems the most suitable method for the assessment of driving ability, this may not be fair. In the future, we hope to have better methods of assessing the risk of accidents. Until that time, we should apply current law prudently, and mainly preclude from driving those diabetic patients who have experienced loss of consciousness or have needed outside help due to hypoglycaemia.

Automatic image-driven segmentation of the ventricles in cardiac cine MRI.

PURPOSE: To propose and to evaluate a novel method for the automatic segmentation of the heart's two ventricles from dynamic ("cine") short-axis "steady state free precession" (SSFP) MR images. This segmentation task is of significant clinical importance. Previously published automated methods have various disadvantages for routine clinical use. MATERIALS AND METHODS: The proposed method is primarily image-driven: it exploits the spatiotemporal information provided by modern 3D+time SSFP cardiac MRI, and makes only few and plausible assumptions about the image acquisition and about the imaged heart. Specifically, the method does not require previously trained statistical shape models or gray-level appearance models, as often used by other methods. RESULTS: The performance of the segmentation method was demonstrated through a qualitative visual validation on 32 clinical exams: no gross failures for the left-ventricle (right-ventricle) on 31 (29) of the exams were found. A validation of resulting quantitative cardiac functional parameters showed good agreement with a manual quantification of 19 clinical exams. CONCLUSION: The proposed method is feasible, fast, and robust against anatomical variability and image contrast variations.