Quantitative ultrasound or clinical risk factors--which best identifies women at risk of osteoporosis?

Dual energy X-ray absorptiometry (DXA) is the current technique of choice to assess risk of future fracture and to diagnose osteoporosis as defined by bone mineral density (BMD). Guidelines for bone densitometry referral have been published listing clinical risk factors that might be considered grounds for assessment. However, these factors are known to be poorly predictive of subsequent BMD measurement and, accordingly, new inexpensive methods of selecting subjects for assessment should be sought. Quantitative ultrasound (QUS) of bone may be such a technique. Women (n = 250) considered by their general practitioners to be at risk of osteoporosis and who had been referred for DXA measurements of the spine and hip were recruited into the study. All underwent a QUS scan of the heel using a McCue CUBA Clinical machine, which measures broadband ultrasound attenuation (BUA) and velocity of sound (VOS), a clinical risk factor questionnaire, and spine and hip BMD measurement by a Norland XR-26 bone densitometer. Patients were categorized according to published diagnostic criteria for BMD, and these were also applied to the QUS parameters. Risk factors were arbitrarily categorized into "low", "medium" and "high" risk groups. Kappa scores were calculated to analyse the agreement between different techniques. Receiver operator characteristic (ROC) analyses were undertaken to demonstrate the technique with the best sensitivity and specificity for the detection of low BMD at the spine and hip. Analysis of the bone mass data demonstrated only moderate agreement (kappa 0.33) between femoral neck and spine BMD with femoral neck BMD and BUA showing a very similar level of agreement (kappa 0.31). ROC analysis demonstrated that VOS followed by BUA was the best predictor of low BMD, with risk factors alone being significantly poorer; QUS parameters are better predictors than clinical risk factors for women with low BMD and could be used effectively at the primary care level to indicate those who should be considered for full osteoporosis assessment. However, further study into the cost effectiveness of this approach is required.     

Carotid intima-media thickness and distensibility measured by MRI at 3 T versus high-resolution ultrasound

We evaluated an MRI protocol at 3 T for the assessment of morphological and functional properties of the common carotid artery (CCA) in 32 healthy volunteers and 20 patients with high-grade internal carotid artery stenosis. Wall thickness of the CCA was measured by using multislice 2D T2 dark blood fast spin echo sequences and compared with intima-media thickness (IMT) determined by ultrasound. Carotid distensibility coefficient (DC) quantified by blood pressure and CCA diameter change during the cardiac cycle was measured by ECG gated 3D T1 CINE MRI and M-mode ultrasound. Apart from generally higher values in MRI high agreement was found for wall thickness and compliance in volunteers and patients. Remaining differences between both methods may be attributed to slightly different methods for measuring IMT and DC. Our findings indicate that MRI at 3 T is a feasible and promising tool for the comprehensive assessment of normal carotid geometry and function.     

Is point-of-care ultrasound disruptive innovation? Formulating why POCUS is different from conventional comprehensive ultrasound

Background

Point-of-care ultrasound (PoCUS) is spreading throughout Emergency Medicine, Critical Care and Pre-hospital Care. However, there is an underlying inherited conflict with the established specialties performing comprehensive examinations. It has been stated that PoCUS is disruptive innovation. If this is true the definition might open up for a new perspective on differentiating comprehensive ultrasound from PoCUS. PoCUS in the light of disruptive innovation is a different perspective on ultrasound that has not before been academically scrutinized.

Methods

In this paper we investigate if PoCUS is in fact disruptive innovation. This is done by comparative analysis with the point of departure in disruptive innovation theory known from the business world.

Results

We find that a disruptive innovation process is happening. This new knowledge allows us to put forward advice for the stakeholders in the field of ultrasound. It also allows us to challenge the conventional pyramid of expertise used to describe different types of ultrasound. The perspective of this paper is mutual understanding of similarities and differences between conventional and point-of-care ultrasound. Only with this understanding the stakeholders can collaborate and use the full spectrum of ultrasound for the benefit of the patient.

     

Real-time ultrasound elastography: Does it improve B-mode ultrasound characterization of solid breast lesions?

Introduction

Elastography is a non-invasive medical imaging technique that detects tumors based on their stiffness (elasticity). Strain images display the relative stiffness of lesions compared with the stiffness of surrounding tissue as cancerous tumors tend to be many times stiffer than the normal tissue, which “gives” under compression. An image in which different degrees of stiffness show as different shades of light and dark is called an elastogram.

Purpose

To prospectively evaluate the sensitivity and specificity of the real-time sonoelastography as compared with B-mode US for distinguishing between benign and malignant solid breast masses. The density of the glandular breast tissue was taken in consideration in addition to the Breast Imaging Reporting and Data System (BI-RADS) categories of the lesions, with biopsy results as the reference standard.

Methods

A total of 216 candidate solid lesions (123 benign and 93 malignant) in 188 patients were examined with 2-dimensional ultrasonography, elastosonography and mammography (for 147 patients). The lesions were classified according to the density of the glandular breast tissue into low density group (D1) and a high density group (D2) and were categorized with the BIRADS score. Elastographic images were assigned an elasticity score of 1 to 5 (1–3, benign; 4 and 5, malignant) according to the Multi-Center Team of Study and the strain ratios of the lesions were measured. Concordance between the imaging findings and histopathologic results was documented. Statistical analysis was performed and sensitivity, specificity and positive and negative predictive values for both elastography and conventional sonography were calculated.

Results

Elastography showed less sensitivity but higher specificity than conventional sonography in the differentiation of benign from malignant solid lesions: B-mode sonography had sensitivity of 85.1%, specificity of 93.9%, a positive predictive value of 92.5% and a negative predictive value of 87.8%, compared with the sensitivity of 80.1%, specificity of 97.1%, a positive predictive value of 96.8% and a negative predictive value of 82.1% for elastography. Elastography was superior to B-mode US in diagnosing solid lesions in the low density group (D1) (96.6% vs. 92.4% specificity) and less in the dense glandular tissue (97.8% vs. 95.9% specificity).

Conclusions

Real-time sonoelastography is an useful technique for the characterization of benign and malignant solid lesions as it increases the diagnostic specificity comparable to B-mode ultrasound, particularly in both ACR 1 and 2, thus reducing the false-positive rate.     

Can medical learners achieve point-of-care ultrasound competency using a high-fidelity ultrasound simulator?: a pilot study

Background

Point-of-care ultrasound (PoCUS) is currently not a universal component of curricula for medical undergraduate and postgraduate training. We designed and assessed a simulation-based PoCUS training program for medical learners, incorporating image acquisition and image interpretation for simulated emergency medical pathologies. We wished to see if learners could achieve competency in simulated ultrasound following focused training in a PoCUS protocol.

Methods

Twelve learners (clerks and residents) received standardized training consisting of online preparation materials, didactic teaching, and an interactive hands-on workshop using a high-fidelity ultrasound simulator (CAE Vimedix). We used the Abdominal and Cardiothoracic Evaluation by Sonography (ACES) protocol as the curriculum for PoCUS training. Participants were assessed during 72 simulated emergency cardiorespiratory scenarios. Their ability to complete an ACES scan independently was assessed. Data was analyzed using R software.

Results

Participants independently generated 574 (99.7%) of the 576 expected ultrasound windows during the 72 simulated scenarios and correctly interpreted 67 (93%) of the 72 goal-directed PoCUS scans.

Conclusions

Following a focused training process using medical simulation, medical learners demonstrated an ability to achieve a degree of competency to both acquire and correctly interpret cardiorespiratory PoCUS findings using a high-fidelity ultrasound simulator.     

Does the echogenicity of focal liver lesions on baseline gray-scale ultrasound interfere with the diagnostic performance of contrast-enhanced ultrasound?

The objective was to evaluate whether the echogenicity of focal liver lesions (FLLs) on baseline gray-scale ultrasound (US) interferes with the diagnostic performance of contrast-enhanced US (CEUS) for small FLLs. Three-hundred and eighty-eight patients were examined by real-time CEUS using a sulfur hexafluoride-filled microbubble contrast agent. The images of 114 hyperechoic lesions, 30 isoechoic lesions and 244 hypoechoic lesions were reviewed by two blinded independent readers. A five-point confidence level was used to discriminate malignant from benign lesions, and specific diagnoses were made. The diagnostic performances were evaluated by receiver-operating characteristic (ROC) analysis. The diagnostic performances of CEUS on hyperechoic lesions in terms of the areas (Az) under the ROC curve were 0.987 (reader 1) and 0.981 (reader 2), and were 0.987 (reader 1) and 0.984 (reader 2) for iso- and hypoechoic lesions, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.0–95.9%, 93.1–100%, 88.6–100%, 70.0–97.1% and 90.0–95.1%, respectively. The echogenicity of FLLs on baseline gray-scale US does not appear to interfere with the diagnostic ability of CEUS for small FLLs.     

Intracranial artery velocity measurement using 4D PC MRI at 3 T: comparison with transcranial ultrasound techniques and 2D PC MRI

Introduction

4D phase contrast MR imaging (4D PC MRI) has been introduced for spatiotemporal evaluation of intracranial hemodynamics in various cerebrovascular diseases. However, it still lacks validation with standards of reference. Our goal was to compare blood flow quantification derived from 4D PC MRI with transcranial ultrasound and 2D PC MRI.

Methods

Velocity measurements within large intracranial arteries [internal carotid artery (ICA), basilar artery (BA), and middle cerebral artery (MCA)] were obtained in 20 young healthy volunteers with 4D and 2D PC MRI, transcranial Doppler sonography (TCD), and transcranial color-coded duplex sonography (TCCD). Maximum velocities at peak systole (PSV) and end diastole (EDV) were compared using regression analysis and Bland–Altman plots.

Results

Correlation of 4D PC MRI measured velocities was higher in comparison with TCD (r?=?0.49–0.66) than with TCCD (0.35–0.44) and 2D PC MRI (0.52–0.60). In mid-BA and ICA C7 segment, a significant correlation was found with TCD (0.68–0.81 and 0.65–0.71, respectively). No significant correlation was found in carotid siphon. On average over all volunteers, PSVs and EDVs in MCA were minimally underestimated compared with TCD/TCCD. Minimal overestimation of velocities was found compared to TCD in mid-BA and ICA C7 segment.

Conclusion

4D PC MRI appears as valid alternative for intracranial velocity measurement consistent with previous reference standards, foremost with TCD. Spatiotemporal averaging effects might contribute to vessel size-dependent mild underestimation of velocities in smaller (MCA), and overestimation in larger-sized (BA and ICA) arteries, respectively. Complete spatiotemporal flow analysis may be advantageous in anatomically complex regions (e.g. carotid siphon) relative to restrictions of ultrasound techniques.     

Imaging the premature brain: ultrasound or MRI?

Neuroimaging of preterm infants has become part of routine clinical care, but the question is often raised on how often cranial ultrasound should be done and whether every high risk preterm infant should at least have one MRI during the neonatal period. An increasing number of centres perform an MRI either at discharge or around term equivalent age, and a few centres have access to a magnet in or adjacent to the neonatal intensive care unit and are doing sequential MRIs. In this review, we try to discuss when best to perform these two neuroimaging techniques and the additional information each technique may provide.     

Can ultrasound help to define orthopedic surgical complications?

This article aims to describe and illustrate the usefulness of ultrasound in detecting complications of orthopedic implants, metal fixation devices, and other surgical material, with an emphasis on soft-tissue pathology.     

Renal parenchymal diseases: is characterization feasible with ultrasound?

Ultrasound (US) imaging of the kidneys has greatly improved in recent years with introduction of wideband transducers and advances is beamformer technology. US is often the first imaging technique to be employed in patients with renal failure, haematuria or proteinuria, after clinical and laboratory evaluation. After conventional US evaluation, Doppler US (DUS) and resistive indices (RIs) analysis provide renal functional evaluation. Anyway, both sensitivity and specificity of conventional US and DUS in renal parenchymal disease evaluation remains low. In the initial or mild clinical stages of renal parenchymal diseases, kidneys may present normal US morphological appearance and normal RIs values, whereas different renal parenchymal diseases may reveal similar appearance on US and DUS evaluation. Besides, different renal parenchymal diseases may present some distinct features on conventional US and DUS with colour Doppler (CD) and power Doppler (PD) evaluation, even though percutaneous renal biopsy is often necessary to reach definite diagnosis. Renal vasculitides and tubular-interstitial nephropathies are more frequently identified by conventional US and DUS than glomerular nephropathies, since glomerular component accounts only for 8% of the renal parenchyma, whereas the highest percentage is occupied by vascular and tubulo-interstitial component. Follow-up of acute renal failure, during and after medical treatment, is the most useful field of employment of conventional US and DUS techniques, since a progressive lowering of RIs is correlated to a progressive recovery of renal function.     

High intensity focused ultrasound: surgery of the future?

For 50 years, high intensity focused ultrasound (HIFU) has been a subject of interest for medical research. HIFU causes selective tissue necrosis in a very well defined volume, at a variable distance from the transducer, through heating or cavitation. Over the past decade, the use of HIFU has been investigated in many clinical settings. This literature review aims to summarize recent advances made in the field. A Medline-based literature search (1965-2002) was conducted using the keywords "HIFU" and "high intensity focused ultrasound". Additional literature was obtained from original papers and published meeting abstracts. The most abundant clinical trial data comes from studies investigating its use in the treatment of prostatic disease, although early research looked at applications in neurosurgery. More recently horizons have been broadened, and the potential of HIFU as a non-invasive surgical tool has been demonstrated in many settings including the treatment of tumours of the liver, kidney, breast, bone, uterus and pancreas, as well as conduction defects in the heart, for surgical haemostasis, and the relief of chronic pain of malignant origin. Further clinical evaluation will follow, but recent technological development suggests that HIFU is likely to play a significant role in future surgical practice.