Reliability of intrarenal Doppler sonographic parameters of renal artery stenosis

PURPOSE: The goal of this study was to retrospectively evaluate false-negative results of Doppler sonography in the diagnosis of renal artery stenosis (RAS) using intrarenal criteria. METHODS: We reviewed the clinical data and Doppler sonographic data for all patients in whom a diagnosis of RAS had been confirmed angiographically between November 1992 and January 2001. Mean intrarenal acceleration and acceleration time values-data obtained directly from color Doppler sonography-and findings of angiographic examination of the kidneys and stenotic renal arteries were evaluated. RESULTS: During the study period, 55 cases of RAS had been angiographically confirmed in 46 patients (25 male and 21 female; mean age, 50 +/- 19 years [+/- standard deviation]). Intrarenal arterial acceleration, acceleration time values, or both were abnormal in 42 kidneys (76%) (group A) and normal in 13 kidneys (24%) (group B). The mean age +/- standard deviation was significantly higher for patients in group B (60 +/- 12 years) than for those in group A (47 +/- 20 years) (p > 0.05). In group B, most of the stenotic lesions were atherosclerotic, and in all kidneys but 1, the lesions were located at the renal ostium or the proximal half of the artery. CONCLUSIONS: Isolated use of intrarenal Doppler sonographic criteria for RAS may lead to an unacceptably high incidence of false-negative results in the diagnosis of this condition, especially in elderly patients.     

Evaluation of renal artery stenosis with velocity parameters of Doppler sonography.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of velocity parameters for the diagnosis of renal artery stenosis (RAS) with color Doppler sonography and to determine the optimal threshold values for these parameters. METHODS: The study group was composed of 187 renal arteries, which were examined by color Doppler sonography and angiography. Four Doppler parameters, including the peak systolic velocities (PSVs) in the renal and interlobar arteries, the renal-aortic ratio, and the renal-interlobar ratio (RIR), were measured. Receiver operating characteristic curve analysis was performed to determine the optimal parameter. The sensitivity, specificity, and negative and positive predictive values at various threshold values were calculated. RESULTS: Doppler sonographic examination was technically successful in 96% of renal arteries (180/187). The RIR was determined to be the best parameter. With threshold values of RIR greater than 5, PSV greater than 150 cm/s in the renal artery, renal-aortic ratio greater than 2, and PSV less than 25 cm/s in the interlobar artery, the sensitivity values were 88%, 81%, 70%, and 74%, respectively. An RIR greater than 5 and PSV less than 15 cm/s in the interlobar artery provided the optimal combination of parameters, with sensitivity and specificity of 91% and 87%, respectively. CONCLUSIONS: The RIR is the best velocity parameter in the detection of RAS (> or =50%), and its best cutoff is 5. Valuing influencing factors of PSV in the renal artery will help reduce misdiagnosis. The combination of RIR greater than 5 and PSV less than 15 cm/s in the interlobar artery provides the best diagnostic efficiency of RAS.     

Value of Doppler sonography for predicting clinical outcome after renal artery revascularization in atherosclerotic renal artery stenosis.

OBJECTIVE: The purpose of this study was to prospectively evaluate the usefulness of Doppler sonography for predicting blood pressure and renal function improvement after percutaneous renal angioplasty in patients with unilateral atherosclerotic renal artery stenosis. METHODS: Thirty-six patients with successfully revascularized unilateral atherosclerotic renal artery stenosis were included. Patients were evaluated by Doppler sonography before treatment, with the resistive index (RI) and acceleration being measured in both kidneys. Blood pressure, number of antihypertensive drugs, and serum creatinine concentration were assessed before treatment and thereafter during a 23 +/- 15-month (mean +/- SD) period. RESULTS: In 20 of the 36 patients (55%), the RI was less than 0.80 before revascularization. After treatment, blood pressure improved in 17 (85%) of those 20 patients and improved in 8 (50%) of 16 patients with an RI of greater than 0.80 (P < .05). Twenty-five patients had renal insufficiency pretreatment, and 11 (44%) had a baseline RI of less than 0.80. Improvement in renal function after angioplasty was shown in 5 (45%) of these 11 patients and in 4 (28.5%) of 14 in the group with high RI (P > .05, not significant). On analysis of acceleration, blood pressure improved in 9 (69%) of 13 patients with acceleration of greater than 3 m/s(2) and in 16 (69.5%) of 23 with acceleration of less than 3 m/s(2) (P > .05). In patients with renal insufficiency, 5 (50%) of 10 cases with normal baseline acceleration and 4 (27%) of 15 with low acceleration showed improvement in renal function (P > .05). CONCLUSIONS: An elevated RI should not exclude patients from a revascularization procedure because, although renal RI does correlate with blood pressure response to revascularization, it is not a useful parameter in predicting renal function outcome. Acceleration has no prognostic value.     

Evaluation of severe transplant renal artery stenosis with Doppler sonography

PURPOSE: To evaluate and determine Doppler criteria for predicting a severe transplant renal artery stenosis (80%-99% diameter reduction) and to compare the Doppler findings in patients with end-to-end and end-to-side anastomosis. METHODS: We performed Doppler sonography on 16 consecutive patients with transplant renal artery stenosis (TRAS) confirmed by digital subtraction arteriography (DSA). Fourteen patients had end-to-end anastomosis, and 2 had end-to-side anastomosis. Eleven patients were re-evaluated with color Doppler sonography within 4 days after intervention. Seven Doppler parameters, including the peak systolic velocity (PSV) in the renal, iliac and interlobar artery, Pre-PSV ratio (the ratio of the PSV in the renal artery to that in the iliac artery), Post-PSV ratio (the ratio of the PSV in the renal artery to that in the interlobar arteries, acceleration time and resistance index, were measured. In the patients with severe TRAS the measurements of these parameters were compared before and after successful intervention. RESULTS: In the 16 patients with a single transplanted kidney, arteriography demonstrated 14 main renal arteries with severe stenosis, and 3 renal arteries with moderate stenosis. When using the cutoff values of Post-PSV ratio >13, renal artery PSV >4 m/sec, acceleration time >0.06 second, and resistance index <0.5 for the detection of all 14 severe stenoses, the sensitivities were 100%, 71%, 93%, and 50%, respectively. For assessing all 14 severe stenoses and 12 severe stenoses of end-to-end anastomosis, the cutoff value of Pre-PSV ratio >5 had sensitivities of 86% and 100%, respectively. Pre-PSV ratios in severe stenoses of end-to-end anastomosis (range, 5.1-11.5) were significantly greater than those recorded in severe stenoses of end-to-side anastomosis (range, 2.8-3.1). Statistically significant differences before and after successful intervention were found for all 7 Doppler parameters in the 7 patients with severe stenosis. CONCLUSIONS: An 80%-99% diameter reduction of the renal artery can be diagnosed based on a Post-PSV ratio >13 for patients with either end-to-end or end-to-side anastomosis. A Pre-PSV ratio >5 for patients with end-to-end anastomosis and acceleration time >0.06 second are helpful in the diagnosis of severe TRAS.     

Doppler sonographic evaluation of cerebral blood flow in anemia resulting from chronic renal failure.

OBJECTIVE: This study was undertaken to describe Doppler sonographic measurement of cerebral blood flow in anemia secondary to chronic renal failure and to compare the results with data gathered from healthy control subjects. We also aimed to compare vertebral and internal carotid artery blood flows to see whether any alteration of dominance in cerebral blood supply would occur. METHODS: We studied 27 predialytic patients with chronic anemia resulting from chronic renal failure and 20 healthy control subjects by means of extracranial Doppler sonography. In these patients, blood flows of bilateral internal carotid and vertebral arteries were measured, and net vertebral artery, net internal carotid artery, and total cerebral blood flows were estimated. Statistical significance was observed between groups, and the data were correlated with hemoglobin level. Variation of the difference of the Doppler measurements between case and control groups by side (left or right) or disease status (patient or control subject) was analyzed. RESULTS: From the assessed Doppler parameters, only cerebral blood flow and right and net vertebral artery blood flows had a significant difference between groups (P < .05) and showed a negative correlation with hemoglobin level. Vertebral artery blood flow was found to have significant interactions with disease status (P = .009) and side (P = .054). CONCLUSIONS: Right vertebral artery blood flow is most prone to increase in chronic anemia of chronic renal failure. This effect also appears as increasing net vertebral artery blood flow and cerebral blood flow.     

Tardus-parvus Doppler waveform in the renal arteries of an adult patient suggesting aortic coarctation

A 19-year-old man presented with arterial hypertension without blood pressure difference between his upper and lower extremities. Duplex Doppler sonography was performed to rule out renal artery stenosis and revealed a tardus-parvus pattern in both renal arteries as well as in the abdominal aorta, whereas the left subclavian artery showed a normal waveform, suggesting a more distal obstruction. Aortography confirmed a severe aortic coarctation. Because the typical signs and symptoms of aortic coarctation may not be present, especially in adults, a tardus-parvus pattern in the abdominal aorta and its branches, contrasting with a normal pattern in the supra-aortic arteries, should suggest the diagnosis.     

Doppler sonography of renal obstruction: value of venous impedance index measurements.

OBJECTIVE: Arterial resistive index values have poor sensitivity and specificity for alterations in renal perfusion induced by collecting system obstruction. We aimed to determine whether the intrarenal venous impedance index values could be useful in evaluating renal parenchymal compliance in cases of obstruction and in differentiating acute obstruction from chronic cases. METHODS: Fifteen patients with acute renal colic having unilateral stone disease and another 15 patients having unilateral chronic obstruction due to various causes were evaluated sonographically. The diagnosis was confirmed either by computed tomography or intravenous urography in all cases. Fifteen subjects with normal kidneys were investigated as a control group. All patients were examined prospectively by conventional and Doppler sonography. The impedance indices and peak flow signals of the interlobar arteries and veins of both kidneys were calculated from spectral Doppler waveforms in all 3 groups. RESULTS: The mean venous impedance index on the acutely obstructed side was lower than the index on the unobstructed side: 0.25 +/- 0.07 and 0.53 +/- 0.3 (mean +/- SD), respectively (P = .005). The mean venous impedance index on the acutely obstructed side was less than the indices both on the chronically obstructed side and in the control subjects (P > .0001). In acute cases, the mean arterial resistive index on the obstructed side was higher than the index on the unobstructed side: 0.62 +/- 0.06 and 0.57 +/- 0.06, respectively (P = .001). No statistically significant difference was detected between other parameters evaluated for the test and control groups. CONCLUSIONS: Renal venous impedance index values may be helpful in evaluating renal hemodynamics in obstruction and in differentiating acute obstruction from chronic cases when used in conjunction with the arterial resistive index.     

Evaluation of the tardus-parvus pattern in patients with atherosclerotic and nonatherosclerotic renal artery stenosis.

OBJECTIVE: The aim of this study was to evaluate the differences in the tardus-parvus pattern between atherosclerotic and nonatherosclerotic renal artery stenosis (RAS) and to explore the causes of these differences. METHODS: In 81 patients, including a nonatherosclerotic group (29 cases of Takayasu arteritis and 22 cases of fibromuscular dysplasia) and an atherosclerotic group (n = 30), RAS was detected by color Doppler sonography and confirmed by renal arteriography. Doppler spectra were obtained at the upper, middle, and lower pole interlobar arteries, and the one with the most prolonged acceleration time (AT) was selected for recording the AT and resistive index (RI). RESULTS: Renal angiography revealed 16 moderate RASs, 80 severe RASs, and 15 occlusions. No statistically significant differences were found in the AT between the atherosclerotic and nonatherosclerotic groups in the mild (P = .24), moderate (P = .63), and severe stenotic (P = .41) subgroups; however, there were statistically significant differences in the RI between the atherosclerotic and nonatherosclerotic groups in the mild (P < .001), moderate (P < .01), and severe (P < .001) subgroups. The RI values in the atherosclerotic group were much higher than those in the nonatherosclerotic group for the 3 stenotic subgroups. CONCLUSIONS: The AT measurement method used widely now cannot differentiate potential differences in pulsus-tardus waveforms between atherosclerotic and nonatherosclerotic RAS; however, it remains a useful approach to detect RAS. Different RI cutoff values should be established according to atherosclerotic and nonatherosclerotic RAS, and consideration of influencing factors for the RI will help reduce misdiagnosis.     

Smoking prevents the expected postprandial increase in intestinal blood flow: a Doppler sonographic study.

OBJECTIVE: To assess whether cigarette smoking had an effect on superior mesenteric artery postprandial blood flow. METHODS: Forty-six subjects were studied in 3 groups with Doppler sonography. Group A consisted of nonsmokers; groups B and C consisted of smokers. In group B, subjects were allowed to smoke cigarettes postprandially, whereas in group C, postprandial smoking was prohibited. A baseline Doppler evaluation was performed in the fasting state, and consecutive Doppler evaluations were performed postprandially with 30-min intervals for 120 minutes. Doppler sonographic measurements of the superior mesenteric artery, including peak systolic and end-diastolic velocities, resistive index, and diameter, were calculated. Statistical analysis was performed by analysis of variance. RESULTS: All groups showed significant changes with time for all parameters (P < .001 for all). The changes in time were significantly different at 90 and 120 minutes for peak systolic velocity, at 90 minutes for end-diastolic velocity, and at 120 minutes for diameter between groups. Group B had the greatest differences. Compared with group A, changes in peak systolic velocity at 90 to 120 minutes were significantly lower in group B (P = .007 and .006, respectively), and compared with groups A and C, changes in end-diastolic velocity at 90 minutes (P = .006 and .004, respectively) and diameter at 120 minutes (P = .007 and .011, respectively) were significantly lower in group B. CONCLUSIONS: Smoking immediately after meals was associated with a superior mesenteric artery blood flow increase that was lower than expected, which may explain the belief that smoking reduces body weight. Postprandial smoking may have undesired results in patients with chronic intestinal ischemia.     

超声评价移植肾动脉狭窄介入治疗前后的变化

目的探讨彩色多普勒超声对移植肾动脉狭窄（TRAS）介入治疗术前、术后血流动力学改变的观察价值。方法TRAS组患者14例,肾移植术后临床生化及超声检测正常的30例患者为对照组。超声测量其肾动脉主干、段动脉及叶间动脉的收缩期峰值流速（PSV）、阻力指数（RI）及血流加速时间（AT）,分别计算肾动脉分别与段动脉、叶间动脉PSV比值。结果①与对照组比较,TRAS组肾动脉主干狭窄段PSV增快,叶间动脉PSV及RI减小,AT增加,肾动脉主干分别与段动脉、叶间动脉PSV比值增大,差异均有统计学意义（P〈0．05）。②与介入治疗术前比较,TRAS组术后肾动脉主干PSV减低,叶间动脉PSV增高,段动脉PSV减低,叶间动脉RI增高,肾动脉主干分别与段动脉、叶间动脉的PSV比值减低,差异均有统计学意义（P〈0．05）。结论彩色多普勒超声能监测TRAS介入治疗后肾动脉和肾内小动脉流速变化,是筛选诊断的首选方法。     

Duplex Doppler examination in renal disease: evaluation of vascular involvement

Evaluation of renal disease and transplant rejection has been limited to excretory urography, nuclear isotope flow studies and other more invasive procedures. The B-scan ultrasound findings are often nonspecific. The development of duplex pulsed Doppler sonography has permitted evaluation of both arterial and venous flow. Duplex ultrasound studies in patients with a suspected diminution in renal function demonstrated the ability to delineate normal and abnormal flow, limiting the differential diagnosis, and in some cases actually documented an abnormality before gross pathologic changes became evident.     

Diagnosing carotid stenosis by Doppler sonography: state of the art.

OBJECTIVE: The goal of this review article is to present the state of the art in the clinical applications and technical performance and interpretation of carotid sonographic examinations. METHODS: Relevant publications regarding color and duplex Doppler sonography (CDDS) of the carotid arteries extracted from a computerized database (MEDLINE) and from references cited in these articles not appearing on the Internet were reviewed. RESULTS: The ability to quickly and efficiently identify stenosis in the carotid artery is an important goal for clinicians and vascular surgeons. Identification of potentially treatable carotid stenosis enables selection of appropriate candidates for endarterectomy or stent implantation. Advances in performance and interpretation of carotid sonographic studies over the last 20 years have been driven by technological improvements in gray scale and CDDS examinations and have made carotid sonography an important means to reach this goal. On the basis of CDDS, intima-media thickness measurements and plaque location and characterization on gray scale imaging, flow disturbance and areas of stenosis on color Doppler sonography, and flow velocities on spectral Doppler sonography are obtained. The degree of the diameter of a stenosis of the internal carotid artery is the main parameter used for therapeutic approaches. Advantages and limitations of the method are included. CONCLUSIONS: Carotid sonography is a unique imaging method for the investigation of carotid abnormalities. Noninvasive, accurate, and cost-effective, it provides morphologic and functional information. It is increasingly becoming the first and often the sole imaging study before endarterectomy, whereas costly and invasive procedures are reserved for special cases.     

The influence of left renal vein entrapment on outcome after surgical varicocele repair: a color Doppler sonographic demonstration.

OBJECTIVE: To evaluate the impact of left renal vein entrapment on outcome after surgical varicocele repair using color Doppler sonography. METHODS: Eighty-four men had varicoceles on color Doppler sonography (2 right sided, 74 left sided, and 8 bilateral), which were diagnosed on the basis of a venous diameter of 3 mm or greater and venous retrograde flow in the pampiniform plexus of veins during the Valsalva maneuver or when changing from a supine to an upright position. Diagnosis of the left renal vein entrapment was based on the following criteria: antero-posterior diameter of greater than 1 cm and peak velocity of less than 15 cm/s for the left renal vein at the mid portion and anteroposterior diameter of less than 0.2 cm and peak velocity of greater than 110 cm/s (or, alternatively, a diameter ratio and peak velocity ratio of >5) for the left renal vein between the aorta and superior mesenteric artery. All patients underwent surgical varicocele repair. In postoperative follow-up, we compared the presence of left renal vein entrapment with the frequency of varicocele recurrence. RESULTS: Sixteen (19%) of 84 patients had left renal vein entrapment with a left-sided varicocele. Postoperatively (mean follow-up +/- SD, 19.3 +/- 11.7 months), 27 (32.2%) of 84 had varicocele recurrence, including all 16 patients with left renal vein entrapment and 11 (20.1%) of 68 patients without left renal vein entrapment. The varicocele recurrence rate was significantly greater in patients with left renal vein entrapment (P < .001, Fisher exact test). CONCLUSIONS: The presence of left renal vein entrapment resulted in a significantly higher varicocele recurrence rate. Patients with varicoceles should routinely be evaluated for the presence of left renal vein entrapment before surgical repair.     

移植肾肾动脉狭窄的彩色多普勒超声诊断

目的 探讨运用多项彩色多普勒超声（CDUS）指标综合诊断移植肾肾动脉狭窄（TRAS）的的新标准。方法 回顾性分析20例经数字减影血管造影（DSA）证实的TRAS的CDUS指标：移植肾肾动脉收缩期峰值血流速度（PSV）、肾动脉与髂外动脉PSV比值（RIR）、肾动脉与叶间动脉PSV比值（峰值流速后比）和叶间动脉阻力指数（RI）;并与对照组相应指标对比。结果 TRAS组与对照组的上述4项指标之间均存在显著统计学差异（P〈0．001）。新标准具有良好的敏感性（100％）和较高的特异性。结论 新标准能够提高CDUS对TRAS的诊断率。     

Influence of breakfast on hemodynamics after lunch – a sonographic evaluation of mesenteric and cervical blood flows

Hemodynamics is subject to change after eating meals, which may be related to various postprandial physical statuses such as hypotension or daytime sleepiness. Previous studies have shown that blood flow in the superior mesenteric artery (SMA) increases after meals, but conflicting results have been reported regarding blood flow in the common carotid artery (CCA). In those studies, the fasting interval before the meal was not taken into account. For example, eating breakfast shortly before lunch may affect hemodynamics in these vessels. The present study therefore investigated hemodynamics in the CCA and SMA after lunch, comparing cases with and without breakfast. Subjects comprised 24 healthy young adults (mean age, 22 ± 1 years). Duplex Doppler sonography was performed to measure blood flow values for calculating flow volume (FV) before and after lunch until 3 h postprandially, on each day with breakfast and without breakfast, respectively, in every subject. Net FV after lunch did not differ between cases with and without breakfast, either in the SMA or in the CCA. Blood FV in the SMA was significantly increased after eating lunch regardless of whether breakfast was eaten (P<0·05 each). However, FV in the CCA was significantly decreased until 1 h after lunch compared with the preprandial state in cases without breakfast (P<0·05), but not in cases with breakfast. In conclusion, a sudden decrease in FV in the CCA from the preprandial state is seen after lunch when breakfast is skipped.     

Doppler sonographic assessment of posttraumatic reflex sympathetic dystrophy.

OBJECTIVE: To reveal the arterial Doppler sonographic findings in cases of posttraumatic reflex sympathetic dystrophy METHODS: Eleven patients had hand reflex sympathetic dystrophy, and 9 had foot reflex sympathetic dystrophy. The duration of symptoms ranged from 1 to 28 weeks, and the history of fracture ranged from 6 to 48 weeks. Bilateral brachial or popliteal arteries proximal to injuries were evaluated by Doppler sonography with a 7.5-MHz linear transducer. All patients also had triphasic bone scintigraphy and extremity thermography RESULTS: Two patients had monophasic waveforms and 4 had low-pulsatility triphasic waveforms on the affected limbs when compared with the asymptomatic limbs. All opposite asymptomatic limbs had normal triphasic waveforms in these 6 cases. Spectral analysis revealed a loss or decrease of a normal reversed flow component with a reduced pulsatility index on the affected limb. Fourteen other patients had symmetric triphasic waveforms. We observed that the patients who had stage 1 reflex sympathetic dystrophy and warm limbs with durations of symptoms of more than 2 weeks had positive Doppler sonographic findings, whereas all patients with stage 2 reflex sympathetic dystrophy and all with normal skin temperature, regardless of stage, had normal waveforms. CONCLUSIONS: Doppler sonography revealed loss of normal triphasic arterial waveforms in some of the cases of stage 1 disease, whereas many cases of stage 1 disease and all cases of stage 2 disease had normal findings. Therefore, we think that Doppler sonography cannot be used for the diagnosis of reflex sympathetic dystrophy but may help in assessing hemodynamic stages of the disease.