Young female with abdominal pain and intra-abdominal free fluid: The risk of confirmation bias associated with point-of-care ultrasound.

Confirmation bias is an ever-present risk to the rapid decision-making required in emergency departments (EDs). We present a case of a young woman who was brought to ED by ambulance with hypotension, syncope and vaginal bleeding, with a presumptive pre-hospital diagnosis of ruptured ectopic pregnancy. On arrival in ED, she was found to have intra-abdominal free fluid on bedside ultrasound. This finding could have been used by clinicians to confirm their suspicion of a ruptured ectopic; however, with further investigations, it was found that anaphylaxis was the most likely cause of the patient's symptoms. This case highlights that point-of-care ultrasound findings can play a potentially dangerous role in confirmation bias and that we should maintain an open mind when making a diagnosis by treating the patient, rather than the ultrasound picture.

Feature Enhancement in Medical Ultrasound Videos Using Contrast-Limited Adaptive Histogram Equalization.

Speckle noise reduction algorithms are extensively used in the field of ultrasound image analysis with the aim of improving image quality and diagnostic accuracy. However, significant speckle filtering induces blurring, and this requires the enhancement of features and fine details. We propose a novel framework for both multiplicative noise suppression and robust contrast enhancement and demonstrate its effectiveness using a wide range of clinical ultrasound scans. Our approach to noise suppression uses a novel algorithm based on a convolutional neural network that is first trained on synthetically modeled ultrasound images and then applied on real ultrasound videos. The feature improvement stage uses an improved contrast-limited adaptive histogram equalization (CLAHE) method for enhancing texture features, contrast, resolvable details, and image structures to which the human visual system is sensitive in ultrasound video frames. The proposed CLAHE algorithm also considers an automatic system for evaluating the grid size using entropy, and three different target distribution functions (uniform, Rayleigh, and exponential), and interpolation techniques (B-spline, cubic, and Lanczos-3). An extensive comparative study has been performed to find the most suitable distribution and interpolation techniques and also the optimal clip limit for ultrasound video feature enhancement after speckle suppression. Subjective assessments by four radiologists and experimental validation using three quality metrics clearly indicate that the proposed framework generates superior performance compared with other well-established methods. The processing pipeline reduces speckle effectively while preserving essential information and enhancing the overall visual quality and therefore could find immediate applications in real-time ultrasound video segmentation and classification algorithms.

How to set-up and perform contrast-enhanced ultrasound.

Contrast-enhanced ultrasound (CEUS) is an important part of current ultrasound imaging practice. Sonographers, radiologists and other sonologists should consider CEUS as a standard tool in the diagnostic toolbox of ultrasound and utilise it liberally to solve a wide range of imaging problems whilst reducing the need to resort to CT or MRI. Setting up a CEUS service is within easy reach of all motivated practitioners. The initial process requires assessment of the demand for CEUS, ensuring staff readiness, preparing administrative processes and obtaining CEUS supplies. The CEUS examination includes gaining informed consent, ensuring authorisation to administer contrast agent (preferably by means of a standing order), conventional pre-scan of the area of interest, insertion of a peripheral IV cannula, preparation of the contrast agent, initiation of the contrast imaging mode, administration of the contrast agent, performance of the examination and aftercare. A number of other important considerations are discussed including cannulation and IV certification, scopes of practice for sonographers performing CEUS, contrast dosing, scheduling, training, interpretation, reporting and quality control.

Vascular function and mortality in haemodialysis patients: a pilot study.

BACKGROUND: Haemodialysis patients often have impaired vascular function that can contribute to mortality. Endothelial-dependent and -independent vascular function can be assessed using the brachial artery reactivity (BAR) technique that measures flow-mediated dilatation (FMD) and the response to glyceryl trinitrate (GTN), respectively. AIMS: The aim of this pilot study was to determine whether BAR measurements in haemodialysis patients were associated with mortality. METHODS: Brachial artery responses to FMD and administration of GTN were assessed in consecutive haemodialysis patients. Patients were then followed up to 18 months after BAR measurements. RESULTS: Seventeen patients were included in the study. After 18 months of follow-up, patients were divided into two groups: survived (n=12) and deceased (n=5). Patients who survived had a significantly greater median percentage vasodilatation to GTN than those who died (19.1% vs 8.8%; P=0.04); and a significantly greater median area under the diameter change-time curve (318 vs 146 mm/s; P=0.03). However, there were no significant differences between survivors and deceased in median percentage vasodilation to FMD (6.0% vs 4.3%; P=0.21), time to peak dilation (45 vs 40s; P=0.66) or area under the diameter change-time curve (35.5 vs 20 mm/s; P=0.29). CONCLUSION: In this pilot study in a small group of haemodialysis patients, endothelial-independent vasodilatory response to GTN was associated with mortality and was of better prognostic value than the endothelial-dependent response to FMD. This finding needs to be investigated in a larger cohort.

Distal ureteral calculi: US follow-up.

PURPOSE: To assess accuracy of ultrasonographic (US) follow-up of distal ureteral calculi by using computed tomography (CT) and conventional radiography (kidneys, ureters, and bladder) as reference standards. MATERIALS AND METHODS: The study was approved by the Regional Ethics Committee, and written informed consent was obtained. One hundred fifty-eight patients with CT-diagnosed symptomatic ureteral calculi, for whom follow-up imaging was ordered, were enrolled from February 2006 to December 2008. Six were excluded, having not met study entry criteria, with 121 men (mean age, 49 years; range, 20-91 years) and 31 women (mean age, 44 years; range, 34-77 years) completing the protocol with adequate reference standard imaging. Targeted transabdominal US occurred coincidently with follow-up CT (n = 92) or radiography (n = 60), with US evaluation prospectively compared considering sensitivity and specificity. Statistical analysis was performed with a χ(2) test, t test, or paired t test, as appropriate. RESULTS: Results of nine US examinations were nondiagnostic because of inadequate ureteral visualization, and among these, two cases showed residual distal calculi. Of the remaining 143 patients, 33 had residual distal calculi, all visualized with US. There was a single false-positive study, giving sensitivity, including nondiagnostic US examinations, of 94.3% (95% confidence interval [CI]: 80.8%, 99.3%) and specificity of 99.1% (95% CI: 95.3%, 100%). All calculi appeared hyperechoic with posterior acoustic shadowing. Additional diagnostic features included presence of a hypoechoic rim and Doppler twinkle artifact. Mean stone length was 7.2 mm ± 2.6 (standard deviation) (range, 4-18 mm). Mean ureteral length visualized was 36.4 mm (range, 12-77 mm), with calculi positioned at a mean of 13.1 mm ± 11.2 (range, 0-40 mm) from the ureterovesical junction (UVJ). Nondiagnostic results were more likely with bladder volume of 110 mL or less (eight [16%] of 50 vs one [1%] of 102, P = .0009). CONCLUSION: Ureteral calculi within 35 mm of the UVJ can be accurately followed-up by using transabdominal US, which substantially reduces patient radiation burden.

Accuracy of prenatal diagnosis in a tertiary fetal medicine unit.

AIMS: To establish the accuracy of prenatal diagnosis in a tertiary referral fetal medicine unit by comparing those diagnoses made prenatally with diagnoses made at birth until discharge, and with postmortem information from cases that resulted in termination, intrauterine, or neonatal death. METHODS: All cases seen in the Fetal Medicine Unit between 1 June 2004 and 30 November 2005 were collected prospectively and sorted according to diagnosis. Relevant outcome data for these pregnancies were collected including postmortem information. RESULTS: 681 cases seen which accounted for 1219 visits. 198 were classified prenatally as a major abnormality, 46 cases minor, 56 with raised nuchal translucency, and 381 no abnormality. Outcome details were not available for analysis in two cases. Therefore 679 (99.7%) cases were available (711 out of 713 fetuses). Of the liveborns, 93.6% of the prenatal diagnoses were confirmed, 5.1% were resolved (predominantly soft markers), and 1.3% resulted in an additional major abnormality that had a significant clinical effect. Postmortem examinations were performed on 52% fetal or neonatal deaths with a normal or unknown karyotype. There was one new finding at postmortem that changed the fetal medicine diagnosis significantly. CONCLUSIONS: Accuracy of prenatal diagnosis in a tertiary fetal medicine unit is high. Parents and staff need to be aware that not all abnormalities will be detected prenatally, but inaccurate diagnosis is uncommon. Clinical indicators for benchmarking need to be developed.

No relationship between low-density lipoproteins and endothelial function in hemodialysis patients.

BACKGROUND: Relationships between low-density lipoprotein cholesterol and endothelial function in hemodialysis patients have yet to be investigated. Furthermore, current reporting of endothelial function data using flow-mediated dilatation has recognised limitations. The aims of the study were to determine the relationship between low-density lipoproteins and endothelial function in hemodialysis patients and to investigate the validity of determining the area under the curve for data collected during the flow-mediated dilatation technique. METHODS: Brachial artery responses to reactive hyperemia (endothelial-dependent) and glyceryl trinitrate (endothelial-independent) were assessed in 19 hemodialysis patients using high-resolution ultrasound. Lipid profiles and other factors known to effect brachial artery reactivity were also measured prior to the flow-mediated dilatation technique. RESULTS: There were no significant relationships between serum low-density lipoproteins and endothelial-dependent or -independent vasodilation using absolute change (mm), relative change (%), time to peak change (s) or area under the curve (mm x s). In hemodialysis patients with atherosclerosis, area under the curve analysis showed a significantly (p<0.05) decreased endothelial-dependent response (mean+/-S.D.: 19.2+/-17.4) compared to non-atherosclerotic patients (42.3+/-28.6). However, when analysing these data using absolute change, relative change or time to peak dilatation, there were no significant differences between the two groups. CONCLUSIONS: In summary, there was no relationship between low-density lipoproteins and endothelial function in hemodialysis patients. In addition, area under the curve analysis of flow-mediated vasodilatation data may be a useful method of determining the temporal vascular response during the procedure.

Testicular microlithiasis: a case report and review of the literature.

Testicular microlithiasis (TM) is a rare condition in which men have innumerable testicular calcifications. It is increasingly being reported on ultrasound. The published literature has reported an association between confirmed testicular malignancy and testicular microlithiasis. The relationship between TM and the risk of developing malignancy is unclear. The present paper reports a patient with a previously normal scrotal ultrasound except for bilateral sonographically detected TM who developed a testicular tumour. It also discusses the appropriate management of TM after reviewing the published literature.