Discriminatory power of 3.5 MHz convex and 7.5 MHz linear ultrasound probes for the imaging of traumatic splenic lesions: a feasibility study

BACKGROUND: Ultrasound is a powerful tool for recognition of free fluid after blunt abdominal trauma, whereas its role for detection of organ lesions remains to be defined. The objective of this study was to determine the diagnostic value of different ultrasound transducers for the precise detection of visceral damage rather than its surrogates in case of splenic injury. METHODS: After a standardized focused abdominal sonogram for trauma protocol to screen for hemoperitoneum, 37 slim, hemodynamically stable subjects with suspected torso trauma were investigated for the extent of parenchymal lesions of the spleen using a 3.5 MHz curved array and a 7.5 MHz linear device. Helical computed tomographic scanning was carried out as the reference standard in all cases. RESULTS: Twenty patients presented splenic damage. The 7.5 MHz transducer showed higher accuracy than the lower frequency probe for the detection of tissue irregularities (difference in proportions, 16.2%; 95% confidence interval, -1.9%-33.5%). A similar trend was observed for 13 lacerations subsequently progressing to two-timed splenic rupture that required surgery (absolute risk reduction, 8.1%; 95% confidence interval, -7.6%-23.9%). With an observed prevalence of 54% for the presence of splenic injury, organ lacerations could be excluded more confidently using the linear probe (posttest probability, 16% vs. 36%). CONCLUSION: In slim patients, higher frequency linear ultrasound probes can provide therapy-relevant information on the integrity of splenic parenchyma after blunt abdominal trauma.     

714MHz卫星电视接收系统中简易混频组件的研制

本文分析了一般的混频原理和讨论了分米波混频器的特点,提出了用已经大量生产的高频调谐器改制成用于714兆卫星电视接收系统中的混频组件的方法。对获得的实验结果进行了讨论。实验表明,方案切实可行,混频组件具有性能稳定可靠,价格低廉,便于普及等优点。     

Cutaneous 10 MHz ultrasound B scan allows the quantitative assessment of burn depth

Alterations in the epidermis and dermis after a scald burn (deep dermal wound) are sonographically displayed by different echo reflections. Histological slide preparations from various layers of healthy skin were studied to check the ultrasound analysis. Echo reflections of high and low density showed a close correlation to real anatomical structures in the histological slides. The 10-MHz B scan allows the differentiation of 0.1 mm. Heat causes an increase in dermal thickness of between 50 and 100 per cent for the period between 1 and 6 h after injury. Identifying the layers corresponding to the histological slides makes it is possible to measure the distance between the interfaces. This improves the quantitative assessment of both the depth and the area of thermal injury.     

Validation of a 40 MHz B-scan ultrasound biomicroscope for the evaluation of osteoarthritis lesions in an animal model

OBJECTIVE: To evaluate high frequency (40 MHz) B-mode ultrasound for the detection of osteoarthritis (OA) lesions of varying severity in an animal model of OA. DESIGN: Ultrasound biomicroscopy (UBM) was performed on the femoral articular surface of adult rabbits with unilateral transection of the anterior cruciate ligament at 4, 8 and 12 weeks post-surgery and on control rabbits. The articular cartilage was examined and graded macroscopically and histologically for OA lesions. Histological examination was used as a reference to determine sensitivity and specificity of ultrasonographic and macroscopic examination regarding fibrillation and ulceration of articular cartilage. RESULTS: Identification of slight surface irregularities was made possible with UBM. The sensitivity and specificity of UBM were 92.3% and 96.4%, respectively, to detect histological fibrillation and 90.9% and 97.6%, respectively, to identify histological ulceration. Macroscopic examination using India Ink had a sensitivity and specificity of 80% and 96.4%, respectively, for fibrillation and 90.9% and 90.5%, respectively, for ulceration when compared to histology. A high correlation (rsp=0.90) was found between ultrasonographic and histological scores. CONCLUSIONS: UBM of articular cartilage reflects histological structure and can accurately detect early changes such as fibrillation. UBM has the potential to be a valuable tool for the in vivo identification of early lesions of OA and for monitoring the disease or efficacy of novel therapy if it can be packaged in a minimally invasive format suitable for intra-articular imaging.     

Standardized ultrasound diagnosis (13 MHz) of the tendon of the posterior tibial muscle--normal findings in probands with healthy feet

OBJECTIVES: Tibialis posterior dysfunction is often diagnosed at a very late stage. However, the early diagnosis of tibialis posterior dysfunction is crucial for therapeutic aspects and especially for the operative prognosis. The morphological correlate of the tibialis posterior dysfunction consists of degenerative changes and thickening of the posterior tibial tendon [2, 9, 11]. By means of a high frequency linear array transducer, a standardized technique of examination as well as reference values of cross-sections of posterior tibial tendon are introduced. MATERIAL AND METHODS: Investigating 51 healthy subjects (102 feet) without any foot deformities, standardized planes were defined by use of a 13 MHz linear array transducer in order to delineate the posterior tibial tendon. At exact anatomic landmarks, tendon diameters were measured using two longitudinal sections proximal and distal to the medial malleolus. Likewise, two diameters and the resulting roughly calculated cross-section of the tendon were determined, using two transverse sections at the level of the subtalar joint facet and the medial malleolus. The findings obtained by ultrasound in four female patients with the diagnosis of a tibialis posterior dysfunction confirmed during surgery are compared to the aforementioned 51 healthy subjects. RESULTS: A healthy tendon appears homogeneous and echo-rich in orthogonal ultrasound and displays average areas of 18.4 sq.mm. (SD 5.9 sq.mm.) at the subtalar joint facet level and 19.2 sq.mm (SD 4.8 sq.mm.) at medial malleolus level in transverse sections. The corresponding areas obtained in patients with tibialis posterior dysfunction were clearly enlarged than in healthy subjects. In 85% of all feet examined at the level of the medial malleolus, the tendon is surrounded by a hypoechoic halo which has a size smaller than two times the cross-section of the flexor digitorum longus tendon. CONCLUSION AND CLINICAL RELEVANCE: Reference values of tendon thickness and of intratendinous echo-structures at reproducible landmarks facilitate delimitations from pathological tendon alterations. The exact delineation of intratendineal echoes by high frequency array transducers and standardized examination techniques that measure tendons size is a prerequisite to enable an early assessment and registration of degenerative alterations and thickening of the posterior tibial tendon.     

Imaging of immature articular cartilage using ultrasound backscatter microscopy at 50 MHz

A high frequency sonographic technique–ultrasound backscatter microscopy–was used to visualize the subsurface structure of immature porcine articular cartilage from the knee joint. In 20-week-old pigs, all parts that were scanned, except the weight-bearing regions of the femoral condyles, demonstrated heterogeneous ultrasound backscatter characteristics within the articular cartilage. A trilaminar pattern consisting of hypoechoic, hyperechoic, and anechoic layers ranging from superficial to deep generally was observed, except in the weight-bearing regions of the femoral condyles, where a homogeneous anechoic pattern was seen. In the younger pigs (6 and 10 weeks old), the trilaminar backscatter pattern was not observed. Small, highly echogenic structures that correlated with vascular channels in histologic assessment were observed frequently in the cartilage of younger pigs, but they were seldom present in the cartilage of 20-week-old pigs. Structural details, such as disruption of the subchondral bone and presence of a thickened fibrous layer on the articular surface at the chondrosynovial junction, also were detected with the ultrasound backscatter microscope. We concluded that high frequency ultrasound can be used to visualize the subsurface structure of immature articular cartilage and some of its developmental changes. Further research is required to explain the mechanism underlying the observed backscatter characteristics of immature articular cartilage and to study its potential for the imaging of pathologic changes.     

Quality assessment of distal SAS connector anastomosis by 13 MHz epicardial ultrasound

Objective: During application of a distal coronary bypass connector, we employed 13 MHz epicardial ultrasound to evaluate quantitative caliper measurements for vessel size matching and to assess anastomosis quality after connector deployment. Methods: Two S²AS connector anastomoses were constructed on ex vivo pressure-perfused porcine hearts. Epicardial ultrasound measurements of the connector ring and anastomosis were compared to intravascular ultrasound measurement and cast dimensions. In 21 pigs, anastomotic sites with internal diameter of 2.25–3.0 mm (internal mammary artery, IMA) and 1.8–2.2 mm (left anterior descending coronary artery, LAD) were selected using external caliper and epicardial ultrasound measurements. Anastomoses were visualized and assessed intraoperatively (beating heart, n = 21) and at 3 and 6 months’ follow-up (explanted heart, n = 10 each). Results: Epicardial ultrasound underestimated connector dimension by ≤5% versus intravascular ultrasound and deviated ≤13% from cast dimensions for other anastomotic measurements. Caliper estimates of internal IMA and LAD diameter differed from ultrasound by −3 ± 6% and −2 ± 7% (mean ± SD), respectively. Intraoperatively, the anastomotic orifice was flawless in all animals. It remained fully patent at 3 and 6 months by ultrasound, which was confirmed by histology. The connector to LAD percentage diameter stenosis changed from −12 ± 5% intraoperatively to −1 ± 7% at 3 months and from −5 ± 6% intraoperatively to −16 ± 13% at 6 months, in the growing pig model. Conclusions: In the pig, external caliper measurements provided a reliable quantitative estimate of inner graft and coronary diameter for connector size matching. Epicardial 13 MHz ultrasound is a promising method to assess coronary anastomosis quality even when connector metal is present.     

Robot-assisted 13 MHz epicardial ultrasound for endoscopic quality assessment of coronary anastomoses

In totally endoscopic coronary artery bypass surgery, intra-operative assessment of anastomotic quality is needed. We evaluated the endoscopic application of epicardial ultrasound to visualize the coronary anastomosis and detect a construction error. In 8 pigs (71-78kg), 16 internal mammary artery to left anterior descending coronary artery anastomoses were constructed conventionally, either correctly (n=8) or incorrectly with a suture cross-over construction error (n=8). A 13MHz mini-transducer (15x9x6mm) was introduced through a port and manipulated by the 'da Vinci' system. The chest was re-opened and scanning repeated manually. Postoperatively, macroscopic inspection served as reference and the intra-operative ultrasound images were scored as 'correct' or 'construction error' by two blinded observers. All anastomoses were scored accurately by both observers. One anastomosis constructed to be correct was scored as construction error, due to narrowing of the outflow corner and anastomotic orifice. Ultrasound images corresponded with macroscopic inspection. Closed-chest scan time was about 1.5 times longer than open-chest scan time, 176s (88-464) (median, range) versus 125s (75-314) (P=0.01), respectively. Closed-chest epicardial 13MHz ultrasound scanning required a median of 3min and enabled discrimination between correctly and incorrectly constructed coronary anastomoses.     

Endoscopic localization and assessment of coronary arteries by 13 MHz epicardial ultrasound

BACKGROUND: In totally endoscopic coronary artery bypass grafting the target coronary artery is difficult to locate and assess. We explored the capacity of a high-frequency epicardial ultrasound mini-transducer (Aloka, Tokyo, Japan) to endoscopically locate and assess the left anterior descending (LAD), third obtuse marginal (OM3), and right posterior descending (RDP) coronary arteries. METHODS: In eight pigs, the LAD, OM3, and RDP were endoscopically exposed. The mini-transducer was manipulated by the "da Vinci" telemanipulation system (Intuitive Surgical, Inc, Mountain View, CA) over the unstabilized and stabilized epicardium to identify the target artery, obtain a scout scan, and both transverse and longitudinal images. RESULTS: In both unstabilized and stabilized conditions, the LAD and RDP were identified within a median of 29 seconds. In stabilized conditions, assessment was complete in 112 seconds (92 to 205) (median with range) for the LAD and 140 seconds (54 to 197) for the RDP. Stabilization of the OM3 was required for identification (16 [5 to 60]) and assessment (111 [82 to 225]). Overall identification was correct in 23 of 24 arteries. The OM branches and RDP became fully exposed endoscopically with stroke volume (SV) and mean arterial pressure (MAP) remaining at 67% +/- 11% (mean +/- standard error of the mean) and 70% +/- 5% of baseline values, respectively. Scanning itself did not augment the decrease in SV and MAP significantly. CONCLUSIONS: After proper endoscopic exposure and stabilization, robot-assisted epicardial ultrasound scanning enabled endoscopic identification and assessment of major coronary arteries within a median of 169 seconds per artery. Exposure, stabilization, and scanning were accompanied by an acceptable drop in stroke volume and mean arterial pressure.     

Improvement in accuracy of diagnosis of carotid artery stenosis with duplex ultrasound scanning with combined use of linear array 7.5 MHz and convex array 3.5 MHz probes: validation versus 489 arteriographic procedures

OBJECTIVE: Validity of a method to improve the accuracy of carotid artery duplex scanning was tested in comparison with arteriography. Study Design: In 489 patients who had not previously undergone arteriography, 978 carotid arteries were examined with duplex ultrasound scanning. In method A, a linear array 7.5 MHz transducer with pulsed-wave 4.7 MHz Doppler scanning was used. For the diagnosis and grading of carotid stenosis, peak systolic and end-diastolic velocity of the Doppler waves were recorded. Method B consisted of complete ultrasound imaging and color-flow mapping with a convex array 3.5 MHz transducer with pulsed-wave 2.8 MHz Doppler scanning in all patients who had previously undergone method A. Further velocity measurements were performed at the sites of stenosis. The results of methods A and B were compared with data from neurologic assessment and arteriographic studies. RESULTS: Method B showed significantly higher diagnostic agreement with arteriography than did method A (K 95% confidence interval [CI], 0.87-0.93 vs 0.79-0.85; P <.05), and the number of mistakes in grading stenosis was significantly lower (primarily because of decreased overestimation) in patients with internal carotid kinking (>60 degrees of angulation) (P <.05), distal stenosis (>20 mm from bifurcation) (P <.01), or wide acoustic shadowing (>1 cm) (P <.01) and in those without these conditions (P <.05). Compared with arteriography, diagnostic accuracy with the new method proved higher for carotid stenoses 50% or greater, 60% or greater, 70% or greater, and 80% or greater; no statistically significant difference was found for carotid stenosis 96% or greater or for carotid occlusion. Compared with data from neurologic assessment and arteriography, method B proved more accurate than method A in designating patients for carotid endarterectomy (P =.014). CONCLUSIONS: The new method significantly improved diagnostic reliability of duplex ultrasound scanning, especially in carotid arteries with kinking, distal stenosis, or wide acoustic shadowing (32.2% of all arteries studied). In clinical practice, we suggest additional use of a lower frequency transducer in cases in which these three conditions are found or suspected at first scanning.     

Combined treatment of 8 MHz radiofrequency hyperthermia and irradiation in a patient with mediastinal metastases of renal cancer

A combined therapy of irradiation and 8 MHz radiofrequency hyperthermia using the Thermotron-RF Model 8 was performed on a patient with mediastinal metastasis of renal cancer. The patient was a 74-year-old male, who received left transperitoneal nephrectomy for left renal tumor in December, 1982. Histology report indicated clear cell carcinoma of the kidney. He noticed puffy face and dyspnea in April, 1984. A CT scan showed a mediastinal tumor 57 X 43 X 120 mm in size and right pleural effusion. Aspiration biopsies revealed metastatic adenocarcinoma of the mediastinal lymph nodes. The combined therapy of irradiation and 8 MHz radiofrequency hyperthermia was started in July, 1984. He was irradiated with daily 2.0 Gy, 5 times a week and was heated twice a week within one hour after each irradiation, totally 50 Gy of irradiation and 14 sessions of hyperthermia. After the treatment, 69% tumor regression and disappearance of pleural effusion were obtained. The combined therapy with 28.8 Gy of irradiation and 7 sessions of hyperthermia was added for the regrowth of the tumor in February, 1985. A 30% of tumor regression was achieved, however, there was no improvement of the dyspnea or pleural effusion. He died on April 8, 1985.     

A combined treatment of interferon-alpha, 8 MHz radiofrequency hyperthermia and/or irradiation in a patient with advanced renal cancer

A combined treatment of alpha interferon (INF), 8 MHz radiofrequency (RF) hyperthermia using Thermotron-RF Model 8 and/or irradiation was performed on a patient with advanced renal cancer. The patient was a 52-year-old male, who had received arterial embolization with a gelatin sponge and 60 mg of adriamycin for the right renal tumor in January, 1985. He was referred to our clinic in April, 1985. Computed tomography showed a right renal tumor, 120 x 105 x 80 mm. Histological examination revealed clear cell carcinoma of the right kidney. The tumor was unresectable because of the huge tumor size, invasion into the right lobe of the liver, multiple pulmonary metastases and severe dysproteinemia. From the beginning of May, 1985, administration of 3 x 10(6) units interferon-alpha (INF) daily and radiofrequency (RF)hyperthermia for one hour twice a week were started. By June 11, 1985, 10 sessions of RF-hyperthermia were performed. Thereafter, hyperthermia for the renal tumor was maintained once a week until June, 1986. From the middle of June, 1985, a gradual improvement of dysproteinemia and appetite loss, and a decrease of the right renal tumor size as well as disappearance of febrile attacks were attained. In November, 1985, mediastinal lymph node swelling developed. A combined therapy of RF-hyperthermia twice a week and irradiation with 2.0 Gy daily 5 times a week was started. A total of 14 sessions of RF-hyperthermia and 30 Gy of irradiation were delivered until January, 1986. Intratumoral temperature of the renal tumor reached 44.0 degrees C during the heating.(ABSTRACT TRUNCATED AT 250 WORDS)