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Thứ Hai, 30 tháng 9, 2013

Opthalmic Ultrasound Probes Controlled Through Magnetic Fields



Opthalmic Ultrasound Probes Controlled Through Magnetic Fields

 A new 50-MHz, high-frequency ultrasound biomicroscope (UBM) ophthalmic probe now includes an advanced magnetic transducer.
The scanning motion in the ultrasound is controlled through magnetic fields instead of mechanical movements as in earlier versions.
This new technology offers a faster scanning process, which has increased the image resolution by one-third. Further advantages include a lighter-weight design and less vibration when performing an ultrasound, decreasing user fatigue. The probe’s durability and effectiveness is also improved by eliminating mechanical components.
Quantel Medical (Clermont-Ferrand, France; www.quantel-medical.com) has introduced two new diagnostic ultrasound probes to their flagship ultrasound platform, Aviso, at the American Society of Cataract and Refractive Surgery annual meeting, held April 2013 in San Francisco (CA, USA). The new probes provide enhanced diagnosis capability for posterior and anterior segment ophthalmic conditions.
The new 10 MHz B-scan probe offers similar benefits for posterior pole diagnosis. This B-scan probe provides superior image quality for viewing and assessment of the detailed structures in the vitreous and the orbital wall.
Increased image acquisition rate allows for high-definition characterization of ocular structures and their movements. The dynamic gain functionality of the 10 MHz allows users to adjust settings to find the optimal tissue differentiation in the image, allowing for more visual clarity and better determination of the condition of the eye.
“These two product introductions reflect Quantel’s commitment to developing the most robust and advanced ultrasound technology available to ophthalmologists,” stated Mr. Jean-Marc Gendre, CEO of Quantel Medical. “Image quality and ease of acquisition are two critical features that we strive to improve and provide to our customers.”
The Aviso ultrasound platform is configurable to include the new 50-MHz and 10-MHz probes, as well as biometry and Standardized echography modules. Quantel Medical’s range of posterior and anterior segment ultrasound diagnostic systems provide eye-care physicians of all specialties with a critical tool for determining pathology and obtaining accurate measurements.

Testing Tiles Designed for Ultrasound Treatment of Soft Tissue Injuries



Testing Tiles Designed for Ultrasound Treatment of Soft Tissue Injuries

A new application could help improve the quality of ultrasound treatment for soft tissue injuries such as ligament damage and muscle strains.
Ultrasound is commonly used in physiotherapy to hasten healing of tissue injuries. Ideally, the sound waves should be applied uniformly tothe treatment site, but it is well known that this does not occur typically in practice. This can affect quality of treatment and even  cause damage.
The UK National Physical Laboratory (NPL; Teddington, UK; www.npl.co.uk) has developed a way to quickly map the distribution and intensity of ultrasound, allowing treatment heads to be used to administer the treatment more effectively. The application will signal physiotherapists to sharp “hot-spots,” allowing them to move the head to smooth the intensity or discard it where it could cause more harm than good. It also has potential for manufacturers, who could rapidly evaluate the effect that design alterations have on the intensity distribution.
Piezoelectric-based treatment heads, during treatment, transform electrical energy to mechanical energy, creating the vibrations needed to produce the ultrasound waves. These are transmitted into the target tissue with the aid of a thin layer of coupling gel. The treatment heads actually vibrate in a complex pattern, partly because of the fact that they are extremely resonant devices. This leads to variations in acoustic pressure and acoustic intensity over the treated region, resulting in “hot-spots,” which can cause over-heating and even damage to the tissue. Without carrying out the complicated and time-consuming process of mapping the acoustic field, it is very difficult to know precisely where the acoustic energy is going.
NPL scientists have devised an answer to this hurdle by developing a simple tool to help visualize the distribution and intensity of the acoustic energy. The approach works by using crystals that are thermochromic (in that they lose their color when heated up above a specific trigger temperature). Importantly, the effect is reversible; the crystals regain their original color on cooling.
The tool consists of two-layers; the bottom layer comprises of the thermochromic crystals encapsulated in a polyurethane rubber matrix, which absorbs sound. The top layer is colorless and is employed to capture the heat within the tile. The tile heat generated by the acoustic energy is quickly and evenly trapped, and the crystals turn white as they reach the trigger temperature. This then produces a pattern on the tile, which represents the temperature distribution generated by the treatment head, which in turn relates to the spatial distribution of the acoustic intensity. The pattern can be clearly visible after only 10 seconds of exposure to the ultrasound.
Bajram Zeqiri, an NPL science fellow who led the project, described how you would test an ultrasound treatment head with the tiles. “In clinical practice the new ‘imager’ tiles would be used in much the same way you would treat a patient: by applying coupling gel to the treatment head, coupling it to the tile, switching on for typically 10 seconds, and then removing and observing the resulting image.”
The tiles can be used to quickly monitor for treatment head damage, asymmetric beam-patterns (hot-spots), and more simply to validate whether the devices are actually working at all. The capability to gain comparatively complicated data from a simple and cost-effective device, in such a short period of time, should help improve the quality of physiotherapy ultrasound treatments.

Thứ Bảy, 28 tháng 9, 2013

Sonographic Features of ACD





Sonographic Features of ACD
Several key sonographic features have been described in ACD:
1. A thick hypoechoic wall with a central hyperechoic center (target phenomena), which is seen in up to 40% of cases. This structure is known as the Parulekar pseudokidney (Figure 3). Although it was one of the initial sonographic signs described for the diagnosis of ACD, later studies have found it to be nonspecific. Thus, the primary emphasis is placed on a thickened hypoechoic wall.

2. Diverticula, which are seen in up to 50% of cases (Figures 2, 3, and 7).

3. Changes in pericolic fat. This sign is usually seen as a rigid hyperechoic zone surrounding the colon, representing omental or pericolic fat that is encasing the inflammation (Figures 3, 5, and 7).

4. Enlarged fluid-filled loops of bowel.

5. Air-containing diverticula manifesting as hyperechoic areas within the lumen where there is acoustic shadowing as a result of air residue (Figure 2).

6. An abscess presenting primarily as a cystic mass with hyperechoic debris.

7. Local pain and tenderness on compression.








Sonographic Approach to Evaluating the Abdomen
In scanning the gastrointestinal tract, the graded compression procedure is used. The examination is performed with a curvilinear 3.5–5.0-MHz probe, which is used in the majority of cases. However a high-frequency linear 5–12-MHz probe may also be used, primarily in the pediatric patient, the thin patient, and the elderly patient who has decreased muscula is most helpful in the evaluation of superficial disease affecting the left colon as well as the sigmoid colon. In addition, an endocavitary (transrectal or tranvaginal) probe may be used when indicated for the evaluation of difficult-to-access areas such as the sigmoid colon, keeping in mind that this approach is more invasive, requires additional examination time, and may be a source of discomfort, particularly to the elderly patient. Before commencing the systemic evaluation of the abdomen, it is critical to focus on the patient’s most painful area. It is precisely this ability to communicate with the patient and to perform a focused evaluation in real time that distinguishes sonography from all other diagnostic modalities and renders it an invaluable extension of the physical examination.
Subsequently, it is recommended to perform a systemic evaluation of the abdomen by commencing in the right upper quadrant with the ascending colon, with its characteristic haustra in its constant anatomic location.
From there, the right lower quadrant is evaluated, reaching the blind-ending loop of bowel, the cecum. The terminal ileum and the appendix are then evaluated, followed by the transverse and descending portions of the colon. It is recommended to follow the sigmoid colon into the pelvis and to attempt visualizing the rectum with the bladder as an acoustic window. Optimal visualization may be attained with a half-full bladder. The small bowel is then scanned and recognized by its valvulae conniventes, while paying attention to the perienteric soft tissue and fat. The normal colon is seldom recognized on sonography, and its wall thickness is less than 3 mm (Figure 1). As such, whenever the colonic wall measures greater than 5 mm, underlying disease must be suspected (Figures 2–6). Although bowel gas and peristalsis may hinder a proper sonographic evaluation of the normal gastrointestinal tract, with underlying disease there tends to be a thickened wall, a narrowed lumen, and decreased peristalsis, all of which facilitate the sonographic evaluation. The key to differentiating the sigmoid colon from the small bowel lies in identifying its stable location, visualizing the colonic lumen that lacks vulvulae conniventes, and ascertaining the absence of peristalsis that is normally pathognomonic for the small bowel.

Thứ Tư, 25 tháng 9, 2013

VIRTUAL CYSTOSCOPY USING 3D ULTRASOUND





·         Abstract
Background
Urinary bladder has many inherent characteristics that make it an ideal structure for evaluating with three-dimensional (3D) volume ultrasound (US). The purpose of this study is to evaluate the application of 3D sonography in assessing bladder pathologies.
Materials and methods
One hundred patients were evaluated in this study. The cases were taken from the pool referred for the evaluation of the renal system (kidney, ureter, and bladder) abbreviated as US KUB at our hospital. Few selected observations are presented here. The examination was performed with the bladder filled up to 250-350 ml, or wherever adequate distension was noted with wide separation of the bladder walls. Routine (two-dimensional) 2D scanning was followed with the acquisition of 3D volume using abdominal and endocavitary probes: RAB2-5L, 3D abdominal (2-5 MHz), RIC5-9H endocavitary (5-9 MHz) using an US system. The maximum field of view (FOV) was chosen to encompass the entire bladder volume and to provide depth perception. High-resolution near-field images were acquired using a smaller FOV. After collecting the 3D data, a surface rendering algorithm was used for postprocessing to obtain cystoscopy-like US images of the urinary bladder.
Conclusion
3D virtual cystoscopy is a promising technique for evaluating bladder pathologies. Its multiplanar capabilities and surface rendering capabilities are helpful for further characterizing the lesions seen on 2D US. It can serve as a good road map prior to cystoscopy.

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Results
The trigone region of the bladder and the distal ureters can be seen in detail on the 3D-rendered images shown in Fig. 1 in all of our evaluated patients.



An elderly gentleman who had complaints of increased frequency of micturition was examined in this study.
Routine 2D US revealed an enlarged prostate gland. Using 3D US, the indentation of the median lobe into the base of the bladder was clearly observed (Fig. 2).



In another patient who had undergone transurethral resection of the prostate (TURP), post-TURP changes were noted, similar to those in cystoscopic findings (Fig. 3).



In this study, an ectopic ureteric opening with refluxive “golf-hole” type appearance was localized (Fig. 4A). The patient was a 2-year-old girl having recurrent urinary tract infections and hydronephrosis and hydroureter. The micturating cystourethrogram showed Grade 3 reflux
(Fig. 4B).


In one patient who presented with hematuria, bladder mass was observed. On using 3D US, one could better understand its morphology and spatial orientation. This agreed well with the cystoscopic findings, as shown in Fig. 5.


3D US also delineated diffuse bladder wall urothelial irregularity in patients who experienced burning and urgency of micturition. The diagnosis of cystitis was made, which correlated with urine microscopy, as shown in Fig. 6.
In one elderly patient with obstructive uropathy, diverticula were observed in the 3D cystoscopic view, as shown in Fig. 7.
Using the inversion mode and surface rendering technique, the bladder cast for morphological evaluation of the shape was obtained. One interesting observation was the classical “Christmas tree” appearance of the bladder in a child with a neurogenic bladder, as shown in Fig. 8A. This was an 8-year-old female with sacral agenesis (Fig. 8B).



In a 40-year-old female patient, using endovaginal volume probe, one could observe the adder-head-type morphology of a ureterocele (Fig. 9). This patient’s earlier US had shown mild hydronephrosis on the affected side.




Discussion
Recent advances in computer technology and display techniques have made it possible to obtain virtual endoluminal views of hollow organs similar to those obtained with conventional endoscopy [1].
Bladder is the most suitable anatomical model for 3D US. Being a fluid-filled aperistaltic hollow viscus, there is a considerable contrast gradient between the bladder lumen and its wall. Thus, by making use of a surface rendering algorithm on volumetric data, near cystoscopic images of the bladder can be obtained.
Virtual cystoscopy has been described previously with computed tomography (CT) and magnetic resonance imaging (MRI), where a Foley catheter was utilized for instilling gas or saline. This is, however, invasive in nature in comparison to the 3D US methodology.
In a study by Song JH et al [2],who investigated the role of CT and virtual cystoscopy in detecting bladder tumors, the complications related to catheter removal are described.
The patient, an 80-year-old man, developed the inability to void because of hemorrhage and intravesical clot formation. In this study, no complications were encountered.
Obtaining 3D volumes required additional 10-15 minutes and did not prolong the time of the study unusually.
Ramos [3] evaluated the utility of 3D US for bladder tumors in cases of hematuria and concluded that 3D US was more sensitive than 2D US in diagnosing bladder tumors.
The 3D US showed a sensitivity of 83.3% and a specificity of 100% with positive and negative predictive values of 100% and 93.8%, respectively [3].
In our case of bladder mass, the location, size, and morphologic features of the lesion agreed with the findings on conventional cystoscopy.
Virtual cystoscopy has the potential to localize and characterize lesions in a manner similar to conventional cystoscopy. As it provides an en face view of lesions, surgeons can proceed with conventional cystoscopy with a mental image of the lesion, when a cystoscopic biopsy or follow-up is contemplated [4].
Hirahara et al [5] evaluated the role of four-dimensional (4D) sonography in assessing the bladder shape in patients with lower urinary tracts symptoms and voiding dysfunction. A rotational method using virtual organ computer-aided analysis (VOCAL) was utilized for obtaining the cast of the urinary bladder [5]. Utilizing the inversion mode and surface rendering algorithm, the 3D casts of the bladder was generated to the satisfaction of the urology team (Fig. 8).
Lyon et al [6] graded the ureteric orifices according to their configuration. Accordingly, Grade 0 was a normal cone-shaped orifice; Grade 1, the stadium orifice; Grade 2, the horseshoe orifice; and Grade 3, golf-hole orifice. The appearance of the ureteric orifice changed with increasing severity of reflux [6]. Note the normal cone-shaped ureteric orifice in Fig. 1 and the grossly refluxive type in Fig. 4.
Ureterocele is the balloon dilatation of the intramural portion of the ureter that bulges into the bladder. This bulge can be clearly seen in the rendered view of the bladder base [7].
3D US-based virtual cystoscopy is feasible in the pediatric urinary bladder without sedation. It provides detailed surface information that is not accessible by 2D US, improving the detection of pathologic conditions such as atypically shaped ureteral ostium. 3D US-based cystoscopy may become a valuable adjunct to 2D US of the pediatric
urinary tract and may potentially help in reducing the need for endoscopic cystoscopy [8].
Virtual cystoscopy has some limitations, the most important being its inability to show flat or intramural lesions (carcinoma in situ), which appear as subtle mucosal color changes on conventional cystoscopy [9]. The limitations include the inability to obtain tissue for histologic
examination or to perform endoscopic resection of pedunculated lesions. The technique is less sensitive than conventional cystoscopy in the detection of sessile lesions or very small polyps [10].
3D virtual cystoscopy requires fewer steps for patient preparation; it is inexpensiveandpatient compliance is not an issue, which are the basic attributes of screening tests [11].

3D virtual cystoscopy is a promising technique for evaluating bladder pathologies. Its multiplanar capabilities and surface rendering capabilities are helpful for further characterizing the lesions seen on 2D US. In certain cases, it can be used as a diagnostic modality, especially in circumstances where conventional cystoscopy may not be possible. It can serve as a good road map prior to cystoscopy. Presently, the author feels that it can serve a complimentary adjunctive role prior to cystoscopy, and larger prospective studies are encouraged to establish its further role in clinical practice.