Renal trauma

Urinary tract injury occurs in 10% of all abdominal trauma patients, and the kidney is the most commonly injured organ in the urinary tract. CT with contrast enhancement is the modality of choice for cross-sectional imaging of renal trauma because it quickly and accurately can demonstrate injury to the renal parenchyma, renal pedicles, and associated abdominal or retroperitoneal organs. This article reviews the mechanism, clinical features, imaging modalities, and CT imaging findings according to the classification of the renal trauma. Trauma to underlying abnormal kidneys, iatrogenic renal injuries, and complications of renal trauma are reviewed also.     

Imaging of urinary tract infection in the adult

The diagnosis of urinary tract infection (UTI) in the adult is primarily based on typical patient symptomatology and urinary evaluation for the presence of bacteria and white blood cells. Uncomplicated UTI usually does not require radiological evaluation unless it is recurrent. Imaging should, in general, be reserved for those patients in whom conventional treatment has failed or those who have recurrent or unusually severe symptoms. Patients with conditions predisposing to infection, or complications thereof, such as diabetes mellitus or immunocompromised states, may also benefit from early imaging. If pyonephrosis is suspected, early imaging and possible urgent drainage is also warranted. Intravenous urogram and ultrasound have traditionally been used in the assessment of these patients, allowing detection of calculi, obstruction and incomplete bladder emptying. These imaging techniques, while useful, have limitations in the evaluation of renal inflammation and infection in the adult. Computerised tomography has now become accepted as a more sensitive modality for diagnosis and follow-up of complicated renal tract infection. Contrast-enhanced CT allows different phases of excretion to be studied and can define extent of disease and identify significant complications or obstruction. Nuclear medicine has a limited role in the evaluation of urinary tract infection in adults. Its main role is in the assessment of renal function, often prior to surgery. Magnetic resonance imaging has a limited but increasing role. It is particularly useful in those with iodinated contrast allergies, offering an ionising radiation free alternative in the diagnosis of both medical and surgical diseases of the kidney.     

Imaging of urinary tract infection in the adult

The diagnosis of urinary tract infection (UTI) in the adult is primarily based on typical patient symptomatology and urinary evaluation for the presence of bacteria and white blood cells. Uncomplicated UTI usually does not require radiological evaluation unless it is recurrent. Imaging should, in general, be reserved for those patients in whom conventional treatment has failed or those who have recurrent or unusually severe symptoms. Patients with conditions predisposing to infection, or complications thereof, such as diabetes mellitus or immunocompromised states, may also benefit from early imaging. If pyonephrosis is suspected, early imaging and possible urgent drainage is also warranted. Intravenous urogram and ultrasound have traditionally been used in the assessment of these patients, allowing detection of calculi, obstruction and incomplete bladder emptying. These imaging techniques, while useful, have limitations in the evaluation of renal inflammation and infection in the adult. Computerised tomography has now become accepted as a more sensitive modality for diagnosis and follow-up of complicated renal tract infection. Contrast-enhanced CT allows different phases of excretion to be studied and can define extent of disease and identify significant complications or obstruction. Nuclear medicine has a limited role in the evaluation of urinary tract infection in adults. Its main role is in the assessment of renal function, often prior to surgery. Magnetic resonance imaging has a limited but increasing role. It is particularly useful in those with iodinated contrast allergies, offering an ionising radiation free alternative in the diagnosis of both medical and surgical diseases of the kidney.     

Multi-detector CT urography: effect of oral hydration and contrast medium volume on renal parenchymal enhancement and urinary tract opacification—a quantitative and qualitative analysis

Objective

To assess the effect of oral hydration and contrast-medium volume on renal enhancement and urinary tract opacification in multi-detector CT urography.

Methods

A total of 192 patients were assigned to different protocols with varying doses of contrast agent with and without oral hydration. The attenuation was measured in the renal parenchyma in the unenhanced, nephrographic and excretory phase, and in the urinary tract in excretory phase imaging, respectively. Opacification of the urinary tract was graded on volume rendered images.

Results

Oral hydration did not significantly alter renal parenchymal enhancement in both the nephrographic and the excretory phase (p?>?0.001), but significantly decreased mean attenuation of the urinary tract in the excretory phase (p?≤?0.001), and improved continuous opacification of all ureter segments (p?<?0.01). Higher volumes of contrast medium improved renal parenchymal enhancement (p?≤?0.001) and continuous opacification of the urinary tract (p?≤?0.01).

Conclusion

Oral hydration leads to lower attenuation values in the urinary tract but improves the continuous opacification of the tract. Increase in contrast medium volume leads to higher renal parenchymal enhancement as well as to an increased continuous opacification of the urinary tract. Decrease in contrast medium volume cannot be compensated for by oral hydration in terms of parenchymal enhancement.     

Benign prostatic hyperplasia: clinical overview and value of diagnostic imaging

The term benign prostatic hyperplasia has traditionally been used to describe a constellation of obstructive and irritative voiding symptoms that occur in men as they age. Such symptomatology may be due to a variety of causes, including prostatic enlargement. Thus, the term lower urinary tract symptoms has replaced BPH to describe this symptom complex. The evaluation and treatment of LUTS continues to be a significant part of urology practice in the United States, as well as a significant component of medical resource utilization. Currently, indication for treatment in patients with LUTS is most often based on subjective measurements of symptom severity and bother. Consequently, imaging does not play a major role in the evaluation of such patients. Recent data suggest that the size of the prostate gland may predict which patients with LUTS will develop progressive symptoms and complications. Moreover, both prostate size and the histologic composition of BPH may help to select patients for specific treatment options. Thus, radiologic imaging may eventually play a larger role in the diagnosis and treatment of LUTS in the future. After review of the literature, it appears that routine upper urinary tract imaging in patients with LUTS or BPH is not warranted. Selective use of such imaging tests in patients with BPH and either hematuria, laboratory evidence of renal insufficiency (elevated BUN or creatinine), or a history of urinary tract infection, urolithiasis, previous urinary tract surgery, or congenital or acquired renal disease remains indicated. Local imaging of the prostate can be performed with either MR imaging or TRUS. Although MR imaging provides excellent resolution of internal prostatic anatomy, information with respect to the ratio of glandular to stromal tissue in the prostate, and an accurate estimate of prostate volume, its use in patients with BPH is limited by its high cost and limited availability. In contrast, TRUS remains an important tool in the evaluation of patients with prostatic disease. Similar to MR imaging, TRUS provides excellent images of internal prostatic anatomy and an accurate estimate of prostate volume prior to treatment. In addition, this imaging modality is noninvasive, cost-efficient, easily adapted to office use, and able to provide guidance for transrectal prostate biopsy.     

MR-Bildgebung der Nieren Neue Ansätze in der Diagnostik*

AIM: New diagnostic strategies for evaluation of the kidney by fast MR imaging techniques. MATERIAL AND METHODS: A comprehensive morphologic and functional evaluation of the kidney is proposed using fast MR imaging of renal morphology, multiphase 3D gadolinium MR angiography, MR urography and MR flow measurements. A single MR examination is designed to grade renovascular disease and assess the hemodynamic and functional significance, detect and characterize renal lesions and evaluate the urinary tract. RESULTS: The combined analysis of morphologic and functional data allows reliable assessment of renal artery stenosis, benign and malignant renal masses and diseases of the renal collecting system and ureters, as well as congenital abnormalities in good agreement to the results of conventional imaging modalities. The improved tissue contrast and additional functional information compensates for the disadvantage of a lower spatial resolution. CONCLUSION: Combined morphologic and functional MR examination represents a reliable, non-invasive and cost-effective alternative imaging modality for comprehensive diagnostic evaluation of renal disease.     

Contrast-enhanced harmonic imaging for the diagnosis of vesicoureteral reflux in pediatric patients.

OBJECTIVE: Harmonic imaging using phase or pulse inversion technology is a new sonographic diagnostic modality that has the potential to produce images of a higher quality than can be obtained with the conventional method. The aim of this study was to compare both types of harmonic modalities--tissue and contrast harmonic imaging--with the fundamental imaging mode in contrast-enhanced B-mode sonographic diagnosis of vesicoureteral reflux. SUBJECTS AND METHODS: Fifty-four children presenting for diagnostic examination of vesicoureteral reflux underwent standard sonography of the urinary tract in the fundamental mode, followed by intravesical administration of a galactose-based contrast medium containing microbubbles. The contrast-enhanced sonography was conducted by scanning the bladder and each kidney in transverse and longitudinal planes, from ventral and dorsal views, consecutively in B-mode using fundamental, contrast harmonic, and tissue harmonic imaging modalities. Soft-touch buttons on the console screen were used to alternate between the three imaging options, so that switching from one modality to the other could be done almost instantaneously. For comparison, in each patient, we selected one set of contrast-enhanced images of the bladder and two sets, one ventral and one dorsal, of the kidney. In a series, the images were compared and ranked from 1 to 3, with 1 being the best, with regard to sonomorphology (demarcation of the retrovesical space and renal pelvis as the potential sites to look for vesicoureteral reflux) and reflux detection and conspicuity, if present. RESULTS: In all, 248 sets of images were available for comparison. The delineation of both the retrovesical space and the renal pelvis was found to be best with tissue harmonic imaging in 84% and 96% of the image sets, respectively (p < 0.01). Forty-one sets of images were compared from 27 kidney-ureter image units of 22 children (41%) with reflux. The refluxing microbubbles were much more conspicuous in the harmonic imaging mode (tissue harmonic, 100%; contrast harmonic, 93%) than in the fundamental mode (p < 0.01). In eight kidney-ureter units, the reflux was detected only by using the harmonic imaging modalities. CONCLUSION: Visualization of the urinary tract and detection of ultrasound contrast media is significantly improved by the use of the harmonic imaging modalities. When both fundamental and harmonic imaging options are available, we recommend harmonic imaging for contrast-enhanced sonographic diagnosis of vesicoureteral reflux.     

Antegrade MDCT pyelography for the evaluation of patients with obstructed urinary tract

OBJECTIVE: The purpose of this study was to design an alternative imaging technique to CT urography in patients with high-grade urinary tract obstruction, with or without impaired renal function, that uses the superior resolution of MDCT and avoids IV contrast material administration. CONCLUSION: Antegrade MDCT pyelography is an alternative imaging technique to CT urography in patients with high-grade urinary tract obstruction with or without impaired renal function. It enables accurate diagnosis of the level of obstruction, as well as its etiology, including nephroureterolithiasis, urothelial tumors, primary congenital megaureter, uretero-pelvic junction stenosis, ureteral edema, ureteral stricture, retroperitoneal fibrosis, and pelvic lymphadenopathy.     

Moderne Ultraschalltechniken und ihre Anwendungen am kindlichen Harntrakt

In children ultrasound plays a central role in the diagnostic imaging of the urinary tract. It is used most frequently and as a primary diagnostic option. Consequently, innovations in ultrasound technology and ultrasound contrast media have major impact on pediatric urosonography. Harmonic imaging is a modality that produces artifact-free images with high resolution. It has been shown that harmonic imaging is superior to fundamental mode in many urosonographic indications. Color Doppler is an established imaging modality, but its application for diagnosis of stones in the urinary tract, especially in children, is relatively new. The so-called twinkling sign, a color Doppler artifact at the site where one normally expects the acoustic shadow to be, enhances the conspicuity of the stone. A further development is three-dimensional (3D) ultrasound. It offers better volume measurement of the bladder and kidneys than 2D ultrasound. Contrast-enhanced voiding urosonography has already proven to be a valuable alternative in the diagnosis of vesicoureteral reflux. Thus, a significant decrease of radiation exposure has become possible as it replaces the radiological methods. With the introduction of contrast-specific ultrasound imaging modalities, further improvements in voiding urosonography are emerging.     

Imaging of renal trauma

Trauma is a major cause of death and disability and renal injuries occur in up to 10% of patients with significant blunt abdominal trauma. Patients with penetrating trauma and hematuria, blunt trauma with shock and hematuria, or gross hematuria warrant imaging of the urinary tract specifically and CT is the preferred modality. If there is significant perinephric fluid, especially medially, or deep laceration, delayed images should be obtained to evaluate for urinary extravasation. Most renal injuries are minor, including contusions, subcapsular and perinephric hematoma, and superficial lacerations. More significant injuries include deep lacerations, shattered kidney, active hemorrhage, infarctions, and vascular pedicle and UPJ injuries. These injuries are more likely to need surgery or have delayed complications but may still often be managed conservatively. The presence of urinary extravasation and large devitalized areas of renal parenchyma, especially with associated injuries of intraperitoneal organs, is particularly prone to complication and usually requires surgery. Active hemorrhage should be recognized because it often indicates a need for urgent surgery or embolization to prevent exsanguination.     

Diffusion-weighted MRI of renal cell carcinoma, upper tract urothelial carcinoma, and renal infection: a pictorial review

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a functional imaging technique that derives image contrast from differences in water molecule diffusion within tissues. DW MRI helps detect and characterize renal and urothelial malignancies, may help in differentiating some benign from malignant renal masses, and can also recognize renal and upper urinary tract infections. Patients precluded from receiving intravenous contrast agents may particularly benefit from this technique.     

Serial sonographic evaluation of "buckshot colic" following a penetrating gunshot wound.

This paper demonstrates the findings of various radiologic imaging modalities in a case of shotgun injury to the kidney. This case is unusual because buckshot entered the renal collecting system, and subsequently passed through the urinary tract in the urine, causing "bullet colic." References to such injury in the literature are discussed, along with role of each imaging modality in the initial and subsequent radiologic workup, with particular emphasis on the usefulness of ultrasonography in evaluation of this patient.     

The spectrum of imaging in Currarino triad

The aim of this study was to evaluate the spectrum of findings and the efficacy of different imaging modalities in order to formulate recommendations for diagnostic imaging of Currarino triad (ASP syndrome), including screening of relatives. The imaging films of five female patients (age range 6 weeks to 12 months) were analysed retrospectively. The studied material consisted of US and MRI of the lower spine (5 patients each), lumbosacral plain radiography (4 patients), contrast enema (4 patients), urinary US (2 patients), genitography (1 patient) and myelo-CT (1 patient). Depiction of pathological findings with different imaging modalities was reviewed and validated with special respect to their demonstrability by US. Ultrasonography detected the sacral bony defect as well as the presacral pathology (meningocele and/or tumour) and thereby gave the basic diagnosis in all of the cases. It also depicted tethered cord and urinary tract abnormalities correctly. Magnetic resonance imaging gave a more distinct visualization of pre- and intraspinal pathology with additional demonstration of intraspinal lipoma in two cases. Regarding anorectal and genital malformations, radiographic contrast agent studies had been used in all patients. Two blind-ending retrorectal fistulas, depicted by enema, were missed by MRI. Patients with congenital or early infancy obstipation, anorectal malformations and complex urinary tract malformations should have spinal and pelvic sonography first. A plain film of the sacrum is recommended in equivocal cases. The need for MRI and contrast agent studies depends on the individual pathology, whereas presently MRI has made further radiographic imaging increasingly dispensable. A screening program with lumbosacral US or plain radiography for families with Currarino triad should be obligatory. Received: 22 May 1998; Revision received: 12 November 1998; Accepted: 6 January 1999     

Serial sonographic evaluation of “buckshot colic” following a penetrating gunshot wound

This paper demonstrates the findings of various radiologic imaging modalities in a case of shotgun injury to the kidney. This case is unusual because buckshot entered the renal collecting system, and subsequently passed through the urinary tract in the urine, causing “bullet colic.” References to such injury in the literature are discussed, along with role of each imaging modality in the initial and subsequent radiologic workup, with particular emphasis on the usefulness of ultrasonography in evaluation of this patient.     

Imaging in urinary tract infections: current strategies and new trends

The aim of imaging in a child with urinary tract infection (UTI) is to detect abnormalities that require appropriate treatment or findings that can be acted on to prevent development of complications (hypertension, chronic renal failure or pregnancy-related complications). Imaging protocols in pediatric urinary tract infections are evolving. From strategies based on extensive investigations in all children younger than 7 years of age, we are slowly moving to imaging strategies focused on children at risk of developing renal damage and possibly long-term complications. The article provides an overview on urinary tract infections, their complications and the use of imaging in their management. The different imaging strategies in children with UTIs (including the recommendation of excluding from imaging certain groups of patients) still needs full evaluation. It is interesting to note, however, a slow move from wide use of cystography in all children with UTI, which has been standard practice for many years but was probably not based on solid scientific evidence, toward a more focused use of cystograms in specific groups of children.     

MR urography: examination techniques and clinical applications

Modern MR urography is performed on the basis of two different imaging strategies, which can be used complementarily to cover almost all aspects in the diagnosis of upper urinary tract diseases. The first technique utilizes unenhanced, heavily T2-weighted pulse sequences to obtain static-fluid images of the urinary tract. T2-weighted MR urograms have proved to be excellent in the visualization of the markedly dilated urinary tract, even if the renal excretory function is quiescent. Static-fluid MR urography is less suitable for imaging of disorders that occur in the nondilated collecting system. The second MR urography technique is analogous to the methodology of conventional intravenous pyelography and is, therefore, designated as excretory MR urography. For this purpose, a non-nephrotoxic gadolinium chelate is intravenously administered and after its renal excretion, the gadolinium-enhanced urine is visualized using fast T1-weighted gradient-echo sequences. The combination of gadolinium and low-dose furosemide (5–10 mg) is the key for achieving a uniform distribution of the contrast material inside the entire urinary tract and, secondly, to avoid high endoluminal gadolinium concentrations, which cause signal loss of the urine due to T2^* effects. Gadolinium excretory MR urography allows to obtain high-quality images of both nondilated and obstructed urinary tracts in patients with normal or moderately impaired renal function. This article reviews the principles of T2- and T1-weighted MR urography in detail and informs how to use these techniques safely in potential clinical applications such as chronic urolithiasis, intrinsic and extrinsic tumor diseases, and congenital anomalies. Magnetic resonance urography performed in combination with standard MR imaging offers a potential to reduce the need for invasive retrograde pyelography. Although the economic aspect is still problematic, it is obvious that MR urography will continue to increase its role in clinical uroradiology. Received: 7 July 2000 Revised: 21 August 2000 Accepted: 21 August 2000     

Renal transit time with MR urography in children

PURPOSE: To prospectively evaluate use of dynamic contrast material-enhanced magnetic resonance (MR) urography for measurement of renal transit time (RTT) of a contrast agent through the kidney and collecting system so as to identify obstructive uropathy in children. MATERIALS AND METHODS: One hundred twenty-six children suspected of having hydronephrosis were hydrated prior to undergoing both conventional and dynamic contrast-enhanced MR urography of the kidneys and urinary tract. A three-dimensional sequence was used to track passage of contrast agent through the kidneys. Time between the appearance of contrast material in the kidney and its appearance in the ureter at or below the level of the lower pole of the kidney was defined as RTT. Bland-Altman plots were used to quantify intra- and interobserver performance. In 30 children, a nuclear medicine renogram was also obtained, and the half-life of renal signal decay after furosemide administration was derived and compared with the MR imaging RTT by using receiver operating characteristic curves. RESULTS: On the basis of RTT, kidneys were classified as normal (RTT RTT 490 seconds). Inter- and intraobserver agreement indicated that the technique is both robust and reproducible. Receiver operating characteristic analysis for comparison of results of MR imaging and diuretic renal scintigraphy showed good agreement between the modalities, with a mean area under the curve of 0.90. CONCLUSION: When used in conjunction with morphologic images obtained in the same examination, RTT generally allowed normal kidneys to be differentiated from obstructed and partially obstructed kidneys.     

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     

Imaging of hematuria

Hematuria may have a number of causes, of which the more common are urinary tract calculi, urinary tract infection, urinary tract neoplasms (including renal cell carcinoma and urothelial tumors), trauma to the urinary tract, and renal parenchymal disease. This article discusses the current status of imaging of patients suspected of having urologic causes of hematuria. The role of all modalities, including plain radiography, intravenous urography or excretory urography, retrograde pyelography, ultrasonography, and multidetector computed tomography (MDCT) in evaluation of these patients is discussed. The article highlights the current status of MDCT urography in imaging of patients with hematuria, and discusses various-often controversial-issues, such as optimal protocol design, accuracy of the technique in imaging of the urothelium, and the significant issue of radiation dose associated with MDCT urography.     

Radionuclide imaging of rare congenital renal fusion anomalies

Demonstration of a congenital renal anomaly plays an important role in the treatment of patients with renal infection. These patients are prone to infections because of coexisting urinary tract anomalies such as duplicated ureter, ureter opening anomalies, and urinary stasis. Assessment of renal parenchymal damage resulting from acute or chronic renal infection is the primary indication for radionuclide imaging with Tc-99m DMSA. In addition, this technique allows congenital anomalies to be identified. The authors review congenital renal fusion anomalies identified in children through Tc-99m DMSA imaging. They conclude that Tc-99m DMSA imaging can reveal important diagnostic information about various congenital anomalies, including fusion anomalies.