Citations

Tracheobronchial disruption is an uncommon but severe complication of double lumen endotracheal tube placement. The physical properties of a double lumen tube (large external diameter and length) make tracheobronchial injury more common than that associated with smaller single lumen endotracheal tubes. Here we present the case of an iatrogenic left main bronchus injury caused by placement of a double lumen tube in an otherwise unremarkable airway.

Embolic protection devices are occasionally employed during endovascular interventions to prevent complications caused by embolic debris. However, these devices have imperfect efficacy, confer risk of endovascular trauma, and are expensive. We report a patient with giant cell arteritis and symptomatic axillary artery stenosis, with a perceived elevated risk of distal embolization during endovascular intervention. We describe a straightforward embolic protection technique of brachial pressure cuff inflation during endovascular intervention and aspiration of displaced thrombotic material from the static column of blood. This novel, effective, and cost-free technique could also be employed in other vascular beds during endovascular intervention.

This paper begins with a patient perspective from the first author. Faced with cascading health problems, this author describes her gradual embrace of alternative treatments. While these improved her health, they also set her apart and prompted antagonism from those in conventional medicine. She found she was not alone in benefiting from a more open view of healing, and not alone in being buffeted by the opposing medical views. Two invited commentaries from medical professionals follow, as well as the first author’s response.

ObjectiveTo 1) describe the distribution of patient global assessment (PtGA) scores of disease activity in patients with granulomatosis with polyangiitis (GPA; Wegener's), 2) explore the discordance between PtGA scores and physician global assessment (PhGA) scores of disease activity, and 3) explore whether PtGA scores during disease remission are associated with future disease relapse.MethodsData from the Wegener's Granulomatosis Etanercept Trial (WGET) were used. PtGA and PhGA scores were assessed on 100‐mm visual analog scales (VAS). Presence of active disease was determined using the Birmingham Vasculitis Activity Score for WG (BVAS/WG), and remission was defined as a BVAS/WG score of 0. Disease relapse was defined as a BVAS/WG score of >0 after remission had been achieved. Discordance between PtGA and PhGA scores was defined as a difference of ≥20 points between the two measures. Mixed linear models were used in longitudinal analysis of PtGA scores.ResultsData were obtained from 180 patients in the WGET cohort, seen at a total of 1,719 study visits. The mean ± SD PtGA and PhGA disease activity scores (on 100‐mm VAS) at baseline were 64.2 ± 27.4 and 55.5 ± 23.4, respectively. PtGA–PhGA discordance occurred in 53% of patients at baseline, and this was inversely associated with newly diagnosed disease (as opposed to relapsing disease) at baseline (odds ratio 0.37, 95% confidence interval [95% CI] 0.20–0.68) but not with age, sex, or presence of renal or pulmonary disease. Patients were in disease remission during 62% of the study visits. The mean PtGA score during visits immediately prior to relapse was 4.52 points higher (95% CI 0.66–8.4) than that at other remission visits (P = 0.03).ConclusionPtGA–PhGA discordance is common in GPA. A rise in the PtGA disease activity score during times defined by physicians as periods of remission is associated with subsequent occurrence of disease relapse. These findings support the addition of PtGA as an outcome measure for GPA.

Ultrasound stimulated vibroacoustography has been used to image tissues using the acoustic response of tissues to localized harmonic radiation pressure. The method provides high resolution and high dynamic range images of tissues. The parameter being imaged is a complex combination of scattering, attenuation, and nonlinearity. However, specific use of harmonic or pulsed radiation pressure and subsequent measurement of the tissue response can be used to measure fundamental material properties of tissue. The measurement of shear wave dispersion can be used to estimate elastic shear moduli of tissue. Fundamental model free properties such as elastic storage and loss constants can also be measured. Ultrasound radiation pressure is used to induce free propagating shear waves. The measurable properties of the shear waves are sensitive to only the material properties of the tissue under certain circumstances. Shear moduli in tissue are measured with high accuracy and precision given appropriate models of wave propagation within the geometry of the tissue. Careful use of shear wave propagation and subsequent measurements can provide fundamental measurements of tissue mechanical properties if models are accurate.

Computed tomography (CT) using acoustic waves was invented at about the same time as MRI. The method of computing attenuation from projections was a direct analog of the x-ray CT approach. However, the method of computing speed from the time of flight of the acoustic ray was a larger logical jump. The field started with straight ray, earliest arrival time methods and has matured to what can be termed the full wave equation inversion method. The extension from two dimensions to three, although essential in the body, did not find a practical solution until very recently. The inverse problem represented by this field has found the attention of many investigators over the years. Practical medical implementations continue being investigated by several investigators more than 30 years after the first invention of the method. Acoustic tomography has been applied in nonmedical areas including oceanography, seismic, and solar sciences. Time awaits its success in medicine.

The surface roughness (of about 20 microns) of an acrylic block immersed in water was measured using the acoustic emission pressure field (in the kHz range) induced by the dynamic radiation force of ultrasound (2 MHz). The dynamic radiation force is produced by mixing two beams of different frequencies to excite the probed object. The acoustic emission is a result of object vibration at the difference frequency of the incident ultrasound beams and is detected by a low-frequency hydrophone placed nearby the block. Due to the presence of the block, an ultrasound standing wave field is generated as a result of multiple reflections between the transducer and the block’s surface. The acoustic emission by the block’s surface varies according to its relative position to the transducer. This variation is used to form an image of the surface roughness at two difference frequencies Δf=9.9 and 22.4 kHz. To have a one-to-one map between the surface roughness and the image, the surface variation has to lie within the distance from a maximum to its nearest minimum in the standing wave. Images obtained here demonstrate that vibroacoustography may be used as a powerful tool for the nondestructive inspection and imaging of surface roughness [Mitri et al., Appl. Phys. Lett. 88, 234105 (2006)]. [Work supported by NIH.]

Diagnostic ultrasound images suffer from degradation due to tissues with sound speed inhomogeneities causing phase shifts of propagating waves. These phase shifts defocus the ultrasound beam, reducing spatial resolution and image contrast in the resulting image. We describe a phase aberration correction method that uses dynamic ultrasound radiation force to harmonically excite a medium using amplitude-modulated continuous wave ultrasound created by summing two ultrasound frequencies at f0=3.0 MHz and f0+Δf=3.0005 MHz. The phase of each element of a linear array transducer is sequentially adjusted to maximize the radiation force and obtain optimal focus of the ultrasound beam. The optimization is performed by monitoring the harmonic amplitude of the scatterer velocity in the desired focal region using Doppler techniques. Simulation results show the ability to regain a 3.0-MHz focused field after applying a phase screen with an rms time delay of 95.4 ns. The radiation force magnitude increased by 22 dB and the resolution of the field was regained. Simulation results show that the focus of the beam can be qualitatively and quantitatively improved with this method. [This study was supported in part by Grants EB002640 and EB002167 from the NIH.]

Vibro-acoustography image is a function of the dynamic characteristics of the object at the vibration (difference) frequency (df). The dynamic characteristic of tissue is closely related to pathology. Therefore, it is important to evaluate image features versus df. Here, the influence of df on breast vibro-acoustography images is studied by scanning human breast at various df values ranging from 20 to 90 kHz. The subjects were chosen from a group of volunteers with different breast abnormalities. Images were compared subjectively to study image features and the appearances of breast lesions versus df. It is demonstrated that having a collection of images of the same tissue at different df values generally provides a better perception of the tissue structure and improves lesion identification. In most cases, higher df resulted in a higher signal-to-noise ratio and thus a higher image quality. Finally, a frequency-compounded images was obtained by calculating the weighted sum of images at different df values. It is demonstrated that image compounding normally improves visualization of breast tissue and abnormalities. [Work supported by NIH Grant EB-00535 and Grant BCTR0504550 from the Susan G. Komen Breast Cancer Foundation. Disclosure: Parts of the techniques used here are patented by MF and JFG.]