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.     

Radiologic study of renal colic

Ureterolithiasis is a common disease responsible for a large number of admissions in emergency departments and a wide utilization of imaging studies. The purpose of this review was to analyze the respective role of the different available imaging techniques. Intravenous urography is the gold-standard for diagnosis of acute obstruction, but positive detection of a stone may prove difficult at times. US is less accurate than urography for both diagnoses of obstruction and lithiasis, but it represents a non invasive alternative to IVU (no ionizing radiation and no IV contrast). The information obtained from measurements of intra-renal resistive index is poorly contributive. Non contrast helical CT has become the gold-standard for the diagnosis of ureterolithiasis, the two main factors limiting its widespread use are its accessibility and the radiation exposure. Nevertheless, its excellent diagnostic performance tends to dramatically reduce the need for IVU.     

Echography vs urography in the study of small-size renal carcinoma

Since 1981 we have studied 34 patients with renal cell carcinomas smaller than 3 cm, diagnosed by US and IVP, to evaluate the diagnostic viability of these 2 procedures. Their respective results were compared to pathologic findings and tumor grading. No correlation was found between the type of sonographic patterns and the pathologic findings. On the contrary the correlation between the acoustic pattern and the grading, performed on small tumors and on a control group of large tumors, showed that most tumors in the former group (70%) had lower grading than those in the latter. We conclude that the introduction of US has changed the approach to the diagnosis of renal tumors, allowing their early recognition and characterisation. It is thus hoped that the clinical course of such tumors will be improved.     

Echography: problems and errors in the diagnosis of renal masses

US plays an extremely important role in the diagnosis of renal masses. However, a number of diagnostic difficulties still exists in both identification of the mass and definition of its nature. The most frequent causes of diagnostic errors are discussed. Errors may be due to the radiologist, to technical limitations, and to the lesion itself. The radiologist is responsible for inexperience and negligence (incorrect application of the technique, limited clinical information, poor knowledge of US findings). Technical limitations are due to poor spatial and contrast resolution, to extremely fat patients, and to artifacts. As far as lesions are concerned, cystic and solid masses must be distinguished, since the problems are different. As for cystic lesions, problems are relative to their visualization and to the definition of their nature in cases of atypical or complex cysts, due to the complexity of some US findings. The latter involve both cystic wall and content and are related to calcifications, septa, vegetations, blood, purulent debris. In case of solid masses, problems concern the identification of small renal tumors, the differentiation among the various anatomical variants, the differential diagnosis of benign from malignant tumors, and the evaluation of tumor extent. The authors conclude that, whereas operator-dependent errors can be avoided, those inherent to technical parameters and to the lesion itself represent the diagnostic limitation of US.     

Nuclear scintigraphy in the evaluation of renal colic

Forty patients with acute onset renal colic were studied using technetium-99m DTPA renal scintigraphy. Thirty-two were found to have varying degrees of obstruction. In the obstructed group the level was determined by the scan alone in 24 of 32 cases (75%). When the analysis included an abdominal radiograph, the level of obstruction was ascertained in 29 of 32 cases (91%). A delayed nephrogram, as evidenced by an "empty renal pelvis sign" at 5 minutes, was observed in all but one of the cases of obstruction (97%). Delayed clearance of activity from the pyelocalyceal system or ureter was also seen in 97%. In all cases of obstruction either one or both of these signs were observed. However, delayed clearance was found to be a nonspecific finding and was noted in 25% of nonobstructed cases. The finding of the "empty renal pelvis sign" at 5 minutes was found to be specific and was not seen in the nonobstructed group. The authors conclude that radionuclide renal scanning is an effective method for evaluating selected patients with suspected renal colic.     

Present-day imaging of patients with renal colic

In the past decade alternatives to urography have been proposed for the study of patients with renal colic. In 1992 it was suggested to replace urography with KUB and ultrasonography. In 1993 the combination of KUB and ultrasonography followed by urography in unresolved cases was proposed and, in 1995, it was suggested to replace urography with unenhanced helical CT (UHCT). This article illustrates the contribution of UHCT to the study of patients with renal colic and analyses advantages and shortcomings of the technique compared with other diagnostic approaches. Diagnostics of the patient with renal colic is based on the detection of direct and indirect signs which allow identification of not only the calculus, with a sensitivity of 94–100 % and accuracy of 93–98 % according different authors, but also other signs that can serve to guide patient management and evaluate long-term prognosis. Unenhanced helical CT has the capability to detect extraurinary abnormalities which present with flank pain and mimic renal colic. The examination technique affects the quality of the images and therefore diagnostic accuracy as well as the dose to the patient. With regard to setting parameters, the choice of thickness and table feed should be guided by numerous factors. Multiplanar reconstruction is indicated in the study of the entire ureter course to identify the exact site of the calcification for the urologist to perform an evaluation similar to that obtained by urography. Many authors consider UHCT to be a valuable tool for suggesting the best therapeutic approach. Among these there are also urologists. The evaluation is based on the stone detection, its size and level in the urinary tract. Cost analysis shows that the cost of UHCT is equal to or inferior to the cost of urography. With regard to the dose, different data are reported in the literature. A high pitch (more than 1.5) and a thin collimation (3-mm thickness) are good compromise between quality and dose which can be compared to the dose of normal urography. What is to be done if helical CT is not available? If helical CT is not available, plain film plus ultrasonography should be considered. This approach does not solve all the cases; in unresolved cases urography is indicated. It should also be noted that US has a good sensitivity in detecting other conditions such as biliary lithiasis, acute pancreatitis, acute appendicitis and abdomino-pelvic masses which are responsible for pain that mimics renal colic. In conclusion, IVU should not have any more the priority in investigating the patients with renal colic. Helical CT should be the first choice in imaging a patient with renal colic. If this technique is not available, plain film and ultrasonography should be considered adding urography in unresolved cases.     

Low dose computed tomography in suspected acute renal colic

AIM: To evaluate whether computed tomography (CT) of the renal tract in suspected renal colic using reduced exposure factors maintains diagnostic accuracy. METHODS: Prospective multi-centre cohort study. Patients with suspected renal colic were examined using computed tomography (CT) of the renal tract followed by intravenous urography (IVU) in four different centres with five different CT systems. RESULTS: Sixty-nine patients with suspected renal colic had CT of the renal tract followed by IVU. CT was performed with reduced exposure factors, giving a mean CT effective dose of 3.5 (range 2.8-4.5) mSv compared with 1.5 mSv for IVU. Ureteric calculi were detected in 43 patients: CT and IVU detected 40 (93%) ureteric calculi. CT identified other lesions causing symptoms in five patients and identified renal calculi in 24 patients. IVU identified renal calculi in six patients and made false positive diagnosis of renal calculi in seven patients. Mean examination time for CT was 5 minutes and for IVU was 80 minutes. CONCLUSION: CT examination at reduced exposure factors maintains the diagnostic accuracy recorded in other series.     

Echography in pyelocaliceal tumors

In a study of over 32 pyelocaliceal tumors greater than 1 cm in diameter, the authors review retrospectively the reports of the pyelographic and sonographic documents obtained in these patients before the definitive diagnosis was confirmed by the pathological examination. They observed that pyelography has a much greater diagnostic accuracy than does sonography: 31 confirmed (27) or suspected (4) tumors whereas only one tumor was overlooked (silent kidney) on pyelography and 12 diagnosed tumors, 15 overlooked and 5 diagnostic errors on ultrasonography. However, it should be noted that the results of ultrasonography are much better when the results of the intravenous pyelogram are known than when the latter is performed first. These results are supported by triple-blind re-reading of ultrasonographic documents of tumors of the excretory tract grouped with documents of normal kidneys presenting another disease of the sinus. The authors conclude that ultrasonography must be performed first whenever a tumor of the excretory tract is suspected (especially in case of hematuria) and that in this field, there are essentially two indications for ultrasonography: --To remove a stone (hyperechogenic with a cone of shadow) if there is a pyelocaliceal lacuna of unknown cause. --To establish that obstruction is due to a tumor, in the presence of a silent kidney.     

US detection of renal and ureteral calculi in patients with suspected renal colic

Purpose

The purpose of this study was to determine whether the color Doppler twinkling sign could be considered as an additional diagnostic feature of small renal lithiasis (_5mm).

Methods

181 patients underwent CT scans performed for other pathologies; the images were also analyzed by a radiologists to identify the incidental presence of renal lithiasis equal to or smaller than 5 mm.These patients underwent an abdominal ultrasound examination, including grayscale analysis of the kidneys and color Doppler. Lithiasis were divided into three groups, on the basis of the diagnostic agreement provided by CT and gray scale results. Then, the twinkling sign sensitivity was assessed in the three groups.

Results

The twinkling sign was positive in 177 out of 206 lithiasis (86 %) visible on CT, while the grayscale was absolutely positive in 98 out of 206 lithiasis (47.6%) and doubtful positive in 71 out of 206 lithiasis (31%).The twinkling sign was positive in 100% of absolutely positive and doubtful positive lithiasis on bmode, and in 8 out of 31 lithiasis not visible on b-mode.

Conclusions

In the diagnosis of small renal lithiasis, integrating gray-scale with color Doppler may be the most suitable procedure, because the color-Doppler twinkling sign is able to confirm the doubtful diagnosis of renal lithiasis and to detect some lithiasis that are not visible on b-mode.

     

State of the art trends in imaging renal of colic

Radiology has a primary role in the work-up of renal colic, both to confirm urolithiasis and to help determine management. The traditional imaging has been conventional radiography and intravenous urogram with multidetector non-contrast-enhanced helical computed tomography (NCECT) now the modality of choice. Nuclear medicine studies for renal colic are done now infrequently at most institutions. Ultrasound (US) is often done, especially in the emergency department, and magnetic resonance imaging (MRI) is promising. Radiation dose reduction is now on everyone’s minds: Lower-dose CT techniques are being tested and used, and US and MR are considered as first modalities of choice in pregnant women and children.     

Echography in laryngeal tumors]

During sonographic (US) studies of the neck for the nodal staging of patients with laryngeal neoplasms, the authors observed that, especially in advanced cases, also the primary lesion could be imaged with this method. Therefore, US capabilities were investigated in assessing the local stage of laryngeal neoplasms; the results were compared with clinical and surgical findings. Fifty normal subjects of various ages were previously examined to assess the normal US anatomy of laryngeal structures. The presence of calcifications within the thyroid cartilage is the major obstacle to US imaging of the larynx and is directly related to age; indeed, only 40% of subjects can be examined at the age of 70. Seventeen patients with advanced laryngeal tumors were examined by US. Laryngeal imaging was possible, either in part or completely, in 16 of 17 cases. The results were in agreement with clinical staging in 14 cases; in 2 cases US proved clinical understaging by detecting lesion spread to anterolateral perilaryngeal structures. To conclude, US is not suggested as the method of choice in patients with laryngeal neoplasms. However, in subjects with advanced tumors, also US can image the lesion directly, and even detect tumor spread to surrounding tissues, especially in the anterior and lateral directions. In a few cases, this can contribute to preoperative staging and to select the correct therapeutic approach.