Duplex Doppler US of the kidney: differentiation of obstructive from nonobstructive dilatation

Distinction of the obstructed from the nonobstructed dilated renal collecting system is a difficult problem often requiring interventional procedures and pressure measurements. The authors prospectively performed duplex Doppler ultrasound (US) evaluations in 21 kidneys (obstructed, n = 14; nonobstructed, n = 7) immediately before percutaneous nephrostomy. In addition, ten of the obstructed kidneys were evaluated with follow-up Doppler US after percutaneous nephrostomy. Renal obstruction caused a change in the Doppler waveform detected by means of the resistive index (RI). Thirteen of the 14 obstructed kidneys had a RI value greater than .70, while none of the nonobstructed kidneys had a RI value exceeding .70. Relief of the obstruction resulted in a reduced RI; in nine of ten kidneys, the RI was less than or equal to .70 (similar to that of the nonobstructed kidneys). When a dilated collecting system is being imaged, additional evaluation with duplex Doppler US may help distinguish obstructed from nonobstructed dilatation, which may be of particular benefit in patients with conditions that usually predispose them to collecting system dilatation.     

Renal diuretic duplex Doppler sonography in childhood hydronephrosis

OBJECTIVE: The purpose of this study was to determine the diagnostic value of diuretic duplex Doppler sonography in distinguishing between obstructive and nonobstructive hydronephrosis in children by calculating the resistive indices (RI) before and after administration of furosemide. MATERIAL AND METHODS: We prospectively evaluated 28 kidneys (2 solitary) in 15 patients with unilateral or bilateral neonatal hydronephrosis. All patients underwent diuretic renography and duplex Doppler sonography before and after administration of furosemide. RESULTS: According to the half-time drainage patterns at diuretic renography, 13 kidneys were classified as nonobstructed and 15 as obstructed. At baseline, the mean RI values of nonobstructed and obstructed kidneys were not significantly different (0.66 and 0.64, respectively). Ten minutes after the injection of furosemide, the mean RI values of the nonobstructed and obstructed kidneys were 0.68 and 0.70, respectively. The increase in RI over the baseline 10 min after the diuretic injection was statistically significant (p<0.00001) in the obstructed kidneys. CONCLUSION: The baseline RI value of 0.70 is not a definite value for distinguishing obstructed from nonobstructed systems. An increase in RI of at least 10% over the baseline seems to be a more reliable criterion, especially when it is used in conjunction with diuretic renography.     

Renal transplant pyelocaliectasis: role of duplex Doppler US in evaluation

To distinguish the obstructed from the nonobstructed dilated collecting system of transplanted kidneys without interventional diagnostic measures, the authors prospectively evaluated duplex Doppler analysis (determination of resistive index [RI]) in 35 renal transplant patients with pyelocaliectasis. Proof of the presence or absence of obstruction was obtained at interventional procedures in 18 patients and at clinical follow-up in 17. Thirteen kidneys were obstructed (mean RI, .81 +/- .06), while 22 had nonobstructive dilatation (mean RI, .66 +/- .07). The RI difference was statistically significant (P less than or equal to .01). Of 21 kidneys with a normal RI, only two had obstruction. In both of these, the obstruction was associated with a significant peritransplant collection of fluid due to a ureteral leak. In the seven obstructed transplanted kidneys with follow-up, the mean RI was .82 +/- .06 before nephrostomy and .67 +/- .05 after nephrostomy. Obstruction was a common cause of an elevated RI (greater than or equal to .75). Other causes of transplant dysfunction can be associated with an elevated RI and nonobstructed dilatation. More important, a normal RI should strongly argue against obstruction unless a ureteral leak is also present.     

Intrarenal arterial Doppler sonography in patients with nonobstructive renal disease: correlation of resistive index with biopsy findings

The resistive index (RI), calculated from the duplex Doppler waveform, was compared with clinical and laboratory findings and the results of renal biopsy in 41 patients with nonobstructive (medical) renal disease. Kidneys with active disease in the tubulointerstitial compartment had a mean RI of 0.75 +/- 0.07. This was statistically significantly different (p less than .01) from the RI in kidneys with disease limited to the glomeruli (mean RI of 0.58 +/- 0.05). Acute tubular necrosis resulted in an elevated RI (mean RI = 0.78 +/- 0.03) as did vasculitis/vasculopathy (mean RI = 0.82 +/- 0.05). Patients with hypertension, proteinuria, or hematuria did not have kidneys with a significantly higher RI than did patients without these clinical factors. Kidneys found to be abnormally echogenic did not have an RI significantly different from kidneys of normal echogenicity. There was a weak correlation between creatinine level and RI value, reflected by a linear correlation coefficient of 0.34. In patients with normal renal RIs, the mean creatinine level was 1.7 +/- 1.7, whereas in those with abnormal RI values (greater than or equal to 0.70), the mean creatinine level was 3.7 +/- 3.6. We conclude that some forms of nonobstructive renal disease can produce changes in the Doppler waveform detectable by RI measurement. The production of Doppler waveform changes is strongly influenced by the site of the main disease within the kidneys. Active disease within the tubulointerstitial compartment (acute tubular necrosis, interstitial nephritis) or vasculitis/vasculopathy generally resulted in an elevated RI, whereas disease limited to the glomeruli, no matter how severe, did not significantly elevate the RI. Degree of renal dysfunction as indicated by serum creatinine level probably affects the Doppler waveform to some degree, but the relationship is weak.     

Intrarenal Doppler ultrasound studies in normal and acutely obstructed kidneys.

Renal ultrasound examinations and intrarenal arterial Doppler studies were performed on 48 patients with normal renal tracts and 20 patients presenting with acute renal colic resulting from ureteric calculus, 14 of whom had urographic evidence of renal obstruction. The mean resistance index (RI) of the Doppler waveforms obtained on the 14 obstructed kidneys (70.4 +/- 6.22) was significantly higher than the mean RI of the 96 normal kidneys (62.4 +/- 6.43). The mean difference between the RIs of the obstructed kidneys and their contralateral non-obstructed kidneys (8.37 +/- 4.43) was also significantly higher than the differences in RI seen between pairs of normal kidneys (2.70 +/- 1.71). Five out of 14 obstructed kidneys showed no pelvicalyceal dilatation and could not have been shown to be obstructed on conventional sonography. Four of these five had RI changes suggestive of obstruction and thus 13 of 14 obstructed kidneys would have been identified as obstructed by a combination of Doppler and conventional sonographic findings. 10 of the 14 obstructed kidneys were re-examined after passage of a urinary calculus and nine showed a reduction in the RI of the previously obstructed kidneys. The 10th subsequently required ureterolithotomy.     

Renal transplant rejection. Limited value of duplex Doppler sonography

Over a two-year period, 275 duplex Doppler ultrasound (US) examinations were performed on 75 renal allograft recipients. Retrospective visual analysis of the Doppler tracings was compared to concurrent clinical findings and to biopsy results. One hundred eight of the 176 Doppler examinations (61%) that showed acute rejection clinically or histologically were interpreted as rejection, while 80 of 99 examinations (81%) in clinically normal patients were interpreted as normal. Two hundred thirty-four examinations had resistive index (RI) calculations. Seventy-two of 141 examinations (51%) with RI less than 0.70 had clinical or biopsy evidence of rejection. Studies compared with only concurrent biopsies revealed that 35 of 39 US examinations interpreted as rejection were confirmed histologically, but only one of 32 examinations that appeared normal sonographically was histologically normal. The low sensitivity of Doppler US, whether by waveform analysis or RI calculation, makes it a poor screening test for acute rejection. The findings support the conclusion that Doppler sonography cannot replace biopsy in the evaluation of renal transplant dysfunction, particularly when the waveform analysis is normal and the RI less than 0.70.     

Doppler sonographic renal resistance index and resistance index ratio in children and adolescents with unilateral hydronephrosis

The aim of this study was to evaluate Doppler renal resistance index (RI) and RI ratio (RIR) in differentiating between obstructive and nonobstructive hydronephrosis in children and adolescents. The RI and RIR were measured in 32 healthy examinees (control group) and 29 patients with unilateral hydronephrosis. Ten patients had acute obstruction caused by a ureteric stone. Seven had obstructive hydronephrosis due to uretero-pelvic junction (UPJ) obstruction. Twelve patients had nonobstructive hydronephrosis. In controls the mean RI±S.D. was 0.615±0.04, and RIR 1.045±0.033. In children with acute obstruction RI was 0.692±0.035 and RIR 1.148±0.037. In UPJ obstruction RI was 0.631±0.054 and RIR 1.059±0.047. In nonobstructive dilatation RI was 0.61±0.038 and RIR 1.043±0.042. The RI and RIR differences were statistically significant between controls and patients with acute colic (p<0.01), and between patients with acute obstruction and with nonobstructive hydronephrosis (p<0.01). In detecting acute obstruction RI≥0.70 was found to have a 70% sensitivity and a 92% specificity. The RIR≥1.10 was found optimal to distinguish obstructive from nonobstructive dilatation (sensitivity 90%, specificity 83%). Both RI and RIR are significantly elevated in patients with acute obstruction. Renal Doppler seems to be useful in children and adolescents for the detection of acute renal obstruction, although it cannot differentiate chronic obstruction due to the UPJ obstruction and nonobstructive renal collecting system dilatation. Electronic Publication     

Ultrasound of the kidney: obstruction and medical diseases

Ultrasound has emerged as the primary imaging modality in conditions where either renal obstruction or renal medical disease is suspected on the basis of clinical and laboratory findings. In urinary tract obstruction, pathophysiologic changes affecting the pressure in the collecting system and kidney perfusion are well understood and form the basis for the correct interpretation of real-time US and color Doppler duplex sonography (CDDS). Ultrasound is very sensitive for the detection of collecting system dilatation ("hydronephrosis"); however, obstruction is not synonymous with dilatation, as either obstructive or nonobstructive dilatation may be present. To differentiate these conditions, CDDS with measurement of the resistive index (RI) in the intrarenal arteries is extremely helpful, as obstruction (except in the peracute stage) leads to intrarenal vasoconstriction with a consecutive increase of the RI above the upper limit of 0.7, whereas nonobstructive dilatation does not. Diuretic challenge to the kidney may further enhance these differences in RI between obstruction and dilatation. Based on these findings, the present value of US and CDDS in the assessment of the patient with flank pain or renal colic is suggested, especially with respect to promising results for spiral CT and based on cost analysis. In renal medical disease, distinguishing different pathologic conditions using gray-scale US and CDDS (RI) criteria is still very difficult. Nevertheless, US is the fist-line imaging modality in the patient with renal insufficiency. Electronic Publication     

Radiological investigation for expert and medico-legal purposes

PURPOSE: To investigate whether colour Doppler US can demonstrate haemodynamic differences in patients with renal colic after pharmacological treatment with indomethacin and ketorolac. MATERIALS AND METHODS: We studied 180 consecutive patients with unilateral acute renal colic with colour Doppler US; 90 were treated with indomethacin, 90 with ketorolac. Furthermore, 37 consecutive patients without obstruction (17 treated with indomethacin and 20 with ketorolac) were also examined and considered normal controls. RESULTS: In the patients with renal colic the average resistive index (RI) was significantly greater on the side of the colic after administration of either indomethacin or ketorolac (p<0.001). The average RI in the obstructed kidneys was significantly higher in the patients treated with ketorolac than with indomethacin (p<0.005). No statistically significant differences were shown between the average RIs of the non obstructed kidneys of the patients with renal colic and between the kidneys of the control patients treated with either indomethacin or ketorolac. DISCUSSION AND CONCLUSIONS: Doppler evaluation of patients with renal colic requires careful interpretation after the administration of nonsteroidal anti-inflammatory drugs (NSAIDs), since values of renal RI depend on the drug that has been used to relieve symptoms.     

Doppler-duplex ultrasound in renal colic

Objective: To determine the role of intrarenal Doppler ultrasound (US) in patients with renal colic and to establish the usefulness of this diagnostic method. Materials and methods: In 121 patients with renal colic and 70 healthy individuals, 382 kidneys were examined with color duplex US. Mean intrarenal-arterial resistive index (RI), and the difference of mean RIs (dRI) between both kidneys were determined. In 64 patients, RI and dRI were compared with urographic findings (time of delay pyelogram between both kidneys). Results: In the 70 healthy individuals, RI was 0.62 ± 0.045 and dRI 0.018 ± 0.01. In the 121 patients with renal colic, RI (0.71 ± 0.06) was significantly superior (P < 0.001) with respect to the opposite kidney, with a dRI of 0.09 ± 0.055. In a correlation performed in 64 patients with urographic findings among color doppler US, with a RI ≥ 0.70 and/or dRI ≥ 0.06 as an indicative value of obstruction, sensitivity and specifity were 91.8% for patients with delayed pyelogram (n = 37 patients), and 48.1% for patients with nondelayed pyelogram (n = 27 patients) with a specificity of 92.8% with respect to the group of normal patients. In the group of patients with delayed pyelogram, RI was significantly superior (P < 0.05) in patients with an evolution time greater than 24 hours, in patients with proximal ureteral obstruction and in patients who had signs of pyelonephritis. There were no significant differences in the group of patients with nondelayed pyelograms. Conclusion: Color Doppler US is useful to fundamentally evaluate the consequences of the obstruction on renal function. Other factors such as evolution time of the symptomology, obstruction level, or existence of pyelonephritis can alter the US-Doppler values.     

Acute obstruction of the renal collecting system: the intrarenal resistive index is a useful yet time-dependent parameter for diagnosis

The aim of this study was to determine whether the intrarenal resistive index (RI) can be used for the diagnosis of acute obstruction in patients with renal colic and to determine whether the index is time-related. Seventy patients referred to the Emergency Department with acute renal colic and without known associated renal disease underwent duplex Doppler ultrasonography to determine the intrarenal RI at the symptomatic and asymptomatic side. The age range of the patients was 18–72 years. An RI greater than 0.68 and/or an interrenal difference in RI greater than 0.06 and/or an increase in RI of more than 11 % compared with the normal side proved reliable cut-off values to diagnose acute renal obstruction. In addition, time dependency of the increase in RI was noted. No significant differences were observed within the first 6 h after the onset of symptoms. From 6 to 48 h, however, the mean RI in the affected kidney (0.70 ± 0.06; mean ± SD) was significantly different from that in the normal kidney (0.59 ± 0.04) (P < 0.001). In the same period the mean difference in RI was 0.08–0.13 (P < 0.001). After 48 h the sensitivity of RI dropped substantially. It is concluded that renal duplex Doppler ultrasonography is useful for diagnosing acute renal obstruction between 6 and 48 h after the onset of symptoms. Received 3 April 1997; Revision received 8 October 1997; Accepted 5 November 1997     

Urinary obstruction in renal transplants: diagnosis by antegrade pyelography and results of percutaneous treatment

We reviewed our experience with 51 renal transplants to evaluate the accuracy of antegrade pyelography as compared with that of sonography and nuclear renography in the diagnosis of transplant obstruction. Also, the results of percutaneous treatment were analyzed in 44 of these patients. Obstruction was clinically suspected in all of the patients (increased serum creatinine levels and decreased urine output). Antegrade pyelography showed obstruction in 44 (86%) of the 51 patients, and nephrostomy drainage catheters were inserted. Sonography showed pyelocaliectasis in all 49 cases in which it was performed; in 42, the pyelocaliectasis was due to obstruction (14% false-positive rate). Nuclear renography showed obstruction in only six (18%) of 33 cases in which it was performed; all six cases proved to be obstructed (0% false-positive rate and 82% false-negative rate). Twenty-two (50%) of the 44 patients treated with nephrostomy drainage were managed successfully without surgical intervention; seven of these 22 required balloon dilation of ureteric strictures in addition to catheter decompression of the collecting system. The average duration of catheterization required for successful percutaneous treatment was 35 days. This experience suggests that antegrade pyelography has a definite role in the workup of patients suspected of having renal transplant obstruction. The percutaneous access permits successful catheter drainage. Compared with antegrade pyelography, sonography is reasonably accurate in determining the presence of urinary obstruction, although false-positive diagnoses are found in a substantial number of patients. Nuclear renography is not, however, a useful indicator of obstruction owing to its high false-negative rate. Percutaneous treatment of urinary obstruction in transplantation patients proves successful in approximately 50% of cases.     

Duplex sonography of normal renal allografts

Thirty-five patients with normal renal allografts as well as 10 healthy volunteers with normal native kidneys were examined by duplex sonography. Blood flow measurements were performed in the main renal artery as well as in segmental, interlobar and arcuate arteries. In both groups the normal range of variation in blood flow was defined by using the resistive index (RI). Doppler wave forms and RI of main renal arteries were both similar to those of their branches. In renal allografts as well as in native kidneys the blood flow pattern showed a rapid up-slope in systole followed by a gradual down-slope in early diastole, with a persistent flow throughout diastole. In addition, there was no significant difference in the RI between allografted and native kidneys. The interobserver variability was less than 10 per cent. The mean RI was 0.68 using all data points. Vascular rejection in 11 patients could be discriminated significantly (p less than 0.001). Duplex sonography is useful in evaluating renal blood flow. This simple and non-invasive technique seems to be useful in long-term follow-up of renal allograft recipients.     

Renal Doppler ultrasound examination of ureteral obstruction in rabbits: effects of different sites and degrees of obstruction on renal resistive index

RATIONALE AND OBJECTIVES: We sought to investigate the usefulness of Doppler resistive index (RI) in the diagnosis and follow-up of obstructive uropathy of different degrees and different sites of obstruction. METHODS: Forty-six rabbits were classified as follows: group I, partial unilateral obstruction of the proximal ureter (n = 16); group II, complete unilateral obstruction of the proximal ureter (n = 17); group III, complete unilateral obstruction of the distal ureter (n = 13). The RI of the obstructed and contralateral kidneys was measured preoperatively and postoperatively 1 hour, 6 hours, 1 day, 3 days, 1 week, 2 weeks, and 4 weeks, respectively. In each group, the RI was analyzed for statistical differences in the preoperative versus postoperative kidneys, and the obstructed versus contralateral kidneys. We also analyzed the statistical differences in RIs of the obstructed kidneys, in interrenal RI differences (DeltaRI: RI of the obstructed kidney - RI of the contralateral kidney), and in RI ratio (RI of the obstructed kidney / RI of the contralateral kidney) between the 3 groups. RESULTS: The RIs in the obstructed versus contralateral kidneys were significantly increased (P < 0.05) postoperatively at 1 hour, 1 day, and 2 weeks in group I; 6 hours and 1 week in group II; and 1 hour, 6 hours, and 3 days in group III. In obstructed kidneys, the RIs in the postoperative versus preoperative kidneys were significantly increased (P < 0.05) from 1 hour to 2 weeks in group I and from 1 hour to 4 weeks in group II. There were no statistically significant differences in mean RI, DeltaRI, and RI ratio between the 3 groups during the preoperative and postoperative period. CONCLUSIONS: Doppler RI can be elevated in hydronephrotic kidney as a result of both partial and complete obstruction of the ureter. There are no RI differences among obstructed kidneys with different degree and different site of ureteral obstruction.     

Functional evaluation of the urinary tract by color-Doppler ultrasonography (CDU) in 100 patients with renal colic

INTRODUCTION AND OBJECTIVE: To evaluate if the addition of a renal color-Doppler ultrasonography (CDU) in the setting of acute renal colic improves the sensitivity of conventional sonography. MATERIALS AND METHODS: Between July 2002 and June 2003, 100 patients (median 49 years) with renal colic have been evaluated. Within 24 h of the admission, a CDU study of the urinary tract was performed using a sonograph GE Logiq 500 PRO with a multifrequency (3-5 MHz) convex probe. The following parameters were evaluated: ultrasonography (US) of both kidneys, ureters and bladder; resistive index (RI) of the arciform arteries of both kidneys in three different parenchymal areas; ureteric jets in response to hydration. A renal RI>0.70 and/or a 10% difference between the kidneys were considered as diagnostic of obstructive uropathy; an asymmetric and/or reduced ureteric jet from the ureteric orifices was an additional indicator of obstruction. All patients underwent a CT scan both with and without the administration of contrast medium. RESULTS: Enhanced helical CT demonstrated an urinary stone in 90 out of the 100 patients (90%): 29 pyelic, 28 at the pyelo-ureteral junction, 23 lumbo-iliac and 10 juxtavesical stones. Among 90 patients with urolithiasis, the stone was undetectable with US in 11 cases (12.2%); in 8 cases (8.9%) pyelocalicectasis was absent, and in 6 patients (6.6%) a non-obstructive hydronephrosis was present. Median RI in obstructed and non-obstructed kidney was 0.73 (range 0.71-0.87) versus 0.62 (0.50-0.68), respectively; in two, obstructed kidneys RI was <0.70 but greater than 10% compared with normal side. Sensitivity and specificity of US, CDU (RI+ureteric jet), unenhanced helical CT and CDU in association with unenhanced helical CT were 94.8 and 55.5, 98.9 and 90.9, 100 and 100%, respectively. DISCUSSION AND CONCLUSIONS: CDU in patients with renal colic and/or pelvicalicectasis improves the diagnostic accuracy of US in distinguishing between obstructive and non-obstructive dilatation. Combined with unenhanced CT, CDU has a 100% sensitivity and specificity. Moreover, due to the absence of contraindications and side-effects, CDU is indicated for the follow-up of patients after ESWL, pregnant women and children.     

Resistive Index in Rabbits with Experimentally Induced Hydronephrosis: Effect of Furosemide

RATIONALE AND OBJECTIVES: The purpose of this study in rabbits was to evaluate the effect of furosemide on resistive index (RI) in the diagnosis of partial hydronephrosis. MATERIALS AND METHODS: In 14 rabbits the left ureter was ligated by being tied to an angiographic guide wire. Doppler sonography was performed before and 1 and 6 hours, 1 and 3 days, and 1, 2, and 4 weeks after ureteral ligation. At each interval it was performed both before and after intravenous injection of saline and furosemide. RIs were compared (a) between obstructed and contralateral kidneys and (b) before and after furosemide administration, and the statistical significance of any differences was determined. RESULTS: Obstructed kidneys had significantly higher RIs than the contralateral kidneys before furosemide administration at five of seven postligation measurements and after furosemide administration at all seven. The differences between obstructed and contralateral kidneys were significantly higher after furosemide administration (P < .05). The increase in RI after furosemide administration was significantly greater in obstructed than in contralateral kidneys (P < .05). CONCLUSION: The results in a rabbit model indicate that Doppler sonography with furosemide administration is a valuable method for evaluating hydronephrosis. The administration of furosemide accentuates the difference in RI between obstructed and nonobstructed kidneys.     

Renal vein Doppler sonography of obstructive uropathy

OBJECTIVE: Obstructive uropathy in the early stages can be difficult to diagnose using either standard sonography or the arterial resistive index. We tested the hypothesis that acute obstruction of the renal collecting system reduces the intraparenchymal renal compliance, which affects the intraparenchymal venous blood flow to a greater degree than the arterial flow. SUBJECTS AND METHODS: Twelve patients with clinical evidence of acute obstructive uropathy were referred for helical CT to confirm the diagnosis and to provide a gold standard by which we could evaluate the sonographic findings in the 12 test patients. Twelve patients without renal disease served as a control group. Doppler sonography of the interlobar arteries and veins of both kidneys then was performed, with the sonographer unaware of which kidney had an obstruction. Peak venous flow measurements and arterial resistive and venous impedance indexes were obtained. The impedance indexes of the obstructed and unobstructed kidney were compared for each patient. RESULTS: The mean arterial resistive indexes of the obstructed kidneys were larger than those of the unobstructed kidneys, 0.67 +/- 0.08 and 0.62 +/- 0.05, respectively (p = 0.05). The venous impedance indexes comparing obstructed and unobstructed sides were 0.38 +/- 0.25 and 0.80 +/- 0.25, respectively, a statistically significant result (p = 0.0002). On average, the peak venous flow signal in the obstructed kidney was 69% higher than that of the unobstructed kidney (p = 0.04) and 86% higher than that of the peak venous flow signal in the control group (p = 0.005). CONCLUSION: Renal obstruction alters the venous flow to a greater extent than the arterial flow, and a comparison between the venous flow in the obstructed and unobstructed kidneys may improve diagnostic accuracy.     

From donor to recipient. Doppler US, power US and scintigraphy of kidney perfusion before and after transplantation

PURPOSE: To follow kidneys from the donor to the recipient by assessing whether perfusion changes occur by using duplex Doppler US, power Doppler US and scintigraphy. MATERIAL AND METHODS: The prospective study included 12 donors and their corresponding 12 recipients. For each donor, both donor kidneys were evaluated by duplex Doppler US, power Doppler US and scintigraphy 1 day before surgery. The same procedure was carried out on the renal allografts at days 1, 3, 5 and months 1 and 3 post-transplantation. Power Doppler findings were classified according to a grading system of 1 to 4. Resistive indices (RIs) were determined based on interlobar and segmental arterial flow. Peak systolic velocity and RIs of the main renal artery were also measured. A perfusion parameter named the peak-to-plateau ratio was calculated. Statistical analysis was performed using the paired-samples t-test. RESULTS: Intrarenal RI elevation and decreased renal artery peak systolic velocity was observed in normally functioning recipient kidneys. CONCLUSION: Duplex Doppler sonography demonstrated that transplanted kidneys had an increase in intrarenal vascular resistance at 1 month and a decrease in renal artery peak systolic velocity at 3 months post-transplantation. Scintigraphy and power Doppler US did not reveal any statistically significant perfusion change in normally functioning kidneys from donor to recipient.     

Pulsatile portal vein flow: a sign of tricuspid regurgitation on duplex Doppler sonography

Sonography and duplex Doppler frequently fail to identify a cause for right upper quadrant pain, liver dysfunction, or ascites. The aim of our study was to describe and analyze the pulsatile portal venous waveform in which minimum velocity dropped to or below zero on duplex Doppler sonography and to investigate its possible association with tricuspid regurgitation, one of the causes of liver dysfunction. We correlated the findings in 15 patients in whom this duplex Doppler waveform was seen with the findings on Doppler echocardiography (n = 14) or ultrafast CT (n = 1). All patients had biochemical liver abnormalities or sudden onset of ascites, rapid weight gain, increased abdominal girth, and hepatomegaly. They were referred for sonography to rule out liver metastases, biliary disease, portal vein thrombosis, or Budd-Chiari syndrome. All examinations were done with a 3-MHz phased-array sector transducer with duplex Doppler capability. Seventeen volunteers with no known liver or heart disease served as a control group. We correlated maximum and minimum flow velocities on the portal venous Doppler waveform with the portal vein diameters of the study and control groups. Thirteen patients were later proved to have tricuspid regurgitation, one patient had an aortic-right atrial fistula owing to rupture of an aneurysm of the sinus of Valsalva, and one patient was proved to be normal. In none of the 17 control subjects was this pulsatile portal venous waveform seen. Our study shows that detection of a pulsatile portal venous waveform on duplex Doppler sonography in patients with liver dysfunction should raise the possibility of tricuspid regurgitation.     

MSCT灌注成像对积水肾脏单肾功能评价的实验研究

目的采用多层螺旋CT（MSCT）灌注成像技术测定肾积水模型的各项灌注参数,探讨其对积水肾脏单肾功能的诊断价值。材料与方法8周龄以上成年健康雄性实验大白兔20只,制作右侧输尿管部分梗阻模型．分别在梗阻前、梗阻后4周行MSCT灌注扫描、单光子正电子发射计算机体层成像（SPECT）检查及彩色多普勒超声显像（CDFI）检测,取积水肾脏标本,光镜下观察病理学变化。结果梗阻后4周MSCT灌注成像可见肾盂扩张,肾皮质明显变薄,皮、髓质血流量（BF）、血容量（BV）较梗阻前有明显下降（P〈0．01）,对比剂平均通过时间（MTT）变化无明显差异,肾皮质表面通透性（PS）有轻度下降趋势,但与梗阻前相比,无显著性差异,而肾髓质PS则较梗阻前有显著性降低（P〈0．01）。CDFI显示梗阻后肾动脉、肾内动脉收缩期峰值速度（PSV）均降低（P〈0．05）,舒张末速度（EDV）显著低于梗阻前（P〈0．01）,阻力指数（RI）显著高于梗阻前（P〈0．01）。SPECT测定结果显示梗阻后右肾肾小球滤过率（GFR）均显著低于梗阻前（P〈0．001）,达峰时间（Tb）显著延长（P〈0．001）,半排时间（T（1/2））显著延长,无测定意义。结论肾积水模型在梗阻前、后皮、髓质MSCT灌注参数的变化以BF、BV下降最明显。此结果与CDFI测定的PSV、EDV及RI所反映的肾血流动力学变化相一致。MSCT灌注技术的出现无疑为l临床评价单肾功能开拓了思路,随着MSCT灌注软件的不断发展,其在单肾功能评价方面一定会显示出巨大的临床应用价值。