Doppler sonography in the diagnosis of urinary tract obstruction by stone

Evaluation of the ureteral jet in dogs by using color Doppler ultrasonography

Ureteral jets are the result of a forceful ejection of urine from the vesicoureteral junction into the urinary bladder. By using color Doppler ultrasonography (US), we aimed to identify distinct ureteral jets in dogs, provide insight into ureteral obstruction, and facilitate study of urodynamics and vesicoureteric sphincter function via pulsed Doppler US. Color Doppler US was applied to detect urinary flow from the right ureteral orifices in eight healthy beagles. Under anesthesia, 0.9% saline (2.5 mL/kg/h) and furosemide (0.5 mg/kg) were administered intravenously to assist in detection of distinct ureteral jets and examine their frequency, velocity, duration, and waveform. In all dogs, ureteral jets were visualized under diuresis and anesthesia within 2 to 5 min (mean 3.57 ± 0.90 min) of the furosemide injection. Mean frequency, peak velocity, and duration of right ureteral jets in seven dogs in whom six ureteral jet waveform patterns were identified were 9.86 ± 3.09 jets/min, 34.07 ± 10.02 cm/sec, and 2.82 ± 1.08 sec, respectively. During the 10 min period starting 10 min after the initial jet appeared, only three waveforms were identified. Color Doppler US of ureteral jets may aid in assessing vesicoureteric sphincter function and ureteral abnormalities, such as ureteral obstruction, in dogs.

Changes in renal Doppler ultrasonographic parameters in patients managed with rigid ureteroscopy

BACKGROUND

There has been no study evaluating the intrarenal hemodynamic changes after ureteroscopy in the published literature.

PURPOSE

To determine preoperative and postoperative intrarenal vascular parameters such as resistive index (RI), pulsatility index (PI), peak systolic velocity (PSV), end-diastolic velocity (EDV), measure changes on these values (ΔRI, ΔPI, ΔPSV, ΔEDV) after ureteroscopy (URS) and compare the outcomes with the results of normal contralateral kidneys, and finally investigate possible parameters that would affect renal vascular resistance changes.

MATERIAL AND METHODS

We prospectively studied 47 patients who underwent rigid URS. Preoperative gray-scale and Doppler ultrasonography (CDUS) measurements were obtained 24 h before URS. Similarly, postoperative CDUS measurements were done 24 h after the operation. The degree of hydronephrosis and location of stones in the obstructed kidneys, diameters of both kidneys, and thickness of renal parenchyma were evaluated with gray-scale US followed by CDUS with calculation of the intrarenal RI, PI, PSV, and EDV values for each kidney.

RESULTS

For the operated kidneys, statistically significant P values were noticed when RI and PI values were considered (P < 0.001). ΔRI and ΔPI of the operated kidneys were also significantly greater than the values for non-operated kidneys (P < 0.001). However, it was not the case for ΔPSV and ΔEDV values. In Spearman correlation coefficient analysis, ΔRI was found to be correlated with the parameters: "operative time" and "irrigation fluid volume". No significant relation was documented between ΔRI and the other parameters: age, gender, side of ureteroscopy, stone location, and degree of hydronephrosis.

CONCLUSION

Significant changes in RI and PI values in patients treated with URS reveal that URS can cause a significant increase in renal vascular resistance. With the increase in operative time and irrigation fluid volume used during the operation, RI seems to be significantly increased.

Imaging modalities for urolithiasis: impact on management

PURPOSE OF REVIEW

Urolithiasis is a common urological problem, often requiring efficient workup, accurate diagnosis, and treatment. The purpose of this review is to summarize the imaging modalities employed for the diagnosis of calculi and the caveats of different clinical situations.

RECENT FINDINGS

Noncontrast computed tomography has become the most universally used imaging tool for diagnosing urolithiasis, although ultrasound and magnetic resonance imaging maintain specific roles. Noncontrast computed tomography may provide prognostic information regarding the success of specific management strategies for urolithiasis. Additionally, noncontrast computed tomography is being tested in lower-radiation dose protocols with promising results.

SUMMARY

Considering the well supported accuracy and relative ease of use of noncontrast computed tomography, it has become a logical choice for the urologist to use the technique as a diagnostic tool for stone disease. The future of imaging for intervention and surveillance of stone disease lies in the continued progress of noncontrast computed tomography in terms of patient safety. This will need to be done by developing low-dose radiation computed tomography that can replicate the efficacy of current noncontrast computed tomography.

Role of resistive index in renal colic

We studied the role of duplex Doppler ultrasonography in the diagnosis of renal obstruction caused by ureteral calculi. Using duplex Doppler sonography, we evaluated the intrarenal hemodynamics of 27 patients who presented to the emergency department with renal colic. We performed Doppler ultrasonography on patients in whom US did not reveal any pathology causing renal colic and calculated and compared mean RI values of normal and obstructed kidneys and DeltaRI values of each group. Threshold levels for the diagnosis of urinary tract obstruction (mean RI > or = 0.70 and DeltaRI > or = 0.08) were used to determine the sensitivity and specificity of Doppler sonography for the diagnosis of urinary tract obstruction. Patients were investigated for revealing calculi diagnosis either by stone excretion history, intravenous pyelography or non contrast enhanced urinary computed tomography. A total of 162 intrarenal arterial Doppler recordings were made on 54 kidneys. Of the 16 patients with urinary obstruction, 11 (68%) had sonographic evidence of pelvicalyceal dilatation. The mean RI of the 16 obstructed and 11 unobstructed kidneys was 0.69 +/- 0.04 and 0.61 +/- 0.06 (mean +/- standard deviation), respectively. The difference between the mean RI values for each group was statistically significant (P < 0.05). Mean RI values of the contralateral kidneys in the obstructed group and unobstructed group were 0.61 +/- 0.03 and 0.59 +/- 0.05, respectively. Also DeltaRI value (0.07 +/- 0.02) of obstructed kidney group was statistically higher than the DeltaRI value (0.01 +/- 0.03) of the unobstructed group (P < 0.05). The mean RI of the 16 obstructed kidneys (0.69 +/- 0.04) was significantly greater than that of the 16 unobstructed contralateral kidneys (0.61 +/- 0.03) (P < 0.05). This study supplements the existing evidence that, in acutely obstructed kidneys, renal Doppler recording can demonstrate altered renal perfusion before pelvicalyceal system dilatation and distinguish obstructed and unobstructed kidneys evaluated with suspicion of renal colic.