Ultrasonic evaluation of the unilateral nonvisualized kidney.

There are several techniques for evaluating the nonvisualized kidney. Nephrotomography may be helpful in those patients who have some remaining renal function. Radionuclide renal flow and imaging studies are more sensitive than nephrotomography in detecting hydronephrosis, the most common cause of unilateral renal nonvisualization, but also require some renal function to be of diagnostic value. Diagnostic ultrasound, since it is independent of renal function, is an even more sinsitive indicator of urinary obstruction, detecting those cases where no functioning renal parenchyma is present. This non-invasive technique can accurately guide percutaneous puncture of the collecting system, permitting antegrade localization of the obstructing lesion. When ultrasonography demonstrates a solid mass in the renal fossa, angiography is recommended for definitive diagnosis. When no kidney is identified renal venography may be useful in differentiating between a small nonfunctioning kidney and renal agenesis.     

Imaging in the staging of renal cell carcinoma

Imaging is extremely important in determining the type of surgery undertaken in patients with proven renal cell carcinoma. In this review, the strength and limitation of each of the relevant techniques are outlined, highlighting particularly the correlation between the imaging findings and the pathological staging. Over the past decade, CT has become the most widely used technique for staging renal cell carcinoma, partly due to the very high overall accuracy of up to 90% that has been achieved. MRI appears to have a similar overall accuracy to CTm whereas ultrasound is less accurate than CT or MRI in th overall staging of tumours. However, ultrasound is extremely accurate in identifying and localising the clinically important tumour extension into the intra-hepatic vena cava and right atrium and if local surgical practice requres only a knowledge of venous inevasion, a technically adequate ultrasound examination may suffice. All techniques are unreliable in detecting early perinephric spread.     

Ultraschalldiagnostik der Nierengefäße und der Transplantatniere

Ultrasound is usually the first imaging technique used in clinical practice for the visualization of renal blood vessels, especially when there is suspicion of renal artery stenosis. Apart from B-mode ultrasound, colour Doppler ultrasound, pulsed-wave Doppler are used as well as contrast-enhanced ultrasound, which is being used more and more as a routine technique. Ultrasound is important in nephrology for the detection of renal artery stenosis and the resistance indices from pulse-wave Doppler are also helpful in acute renal failure. Nevertheless resistance indices should be used carefully and always by being aware of the pitfalls of this parameter. Another field of application for ultrasound is imaging of renal blood vessel damage as a result of trauma or iatrogenic damage caused during a biopsy. In this setting contrast-enhanced ultrasound appears to be a suitable and highly sensitive tool for the detection of active bleeding and for visualizing the extent and dynamics of expansion of a hematoma. Ultrasonography is frequently used in the field of kidney transplants for the diagnostics of drainage obstructions, perfusion disturbances, transplant arterial stenoses and lymphoceles. Furthermore, ultrasound is exceptionally well suited for follow-up observation after diagnostic or therapeutic measures (e.g. biopsy and placement or removal of DJ catheters).     

Renal transplant evaluation: multimodality imaging of post-transplant complications

With advancements in surgical techniques and immuno-suppression, renal transplantation is established as the most effective treatment option in patients with end-stage renal disease. Early detection of renal allograft complications is important for long-term graft survival. Late clinical presentation often causes diagnostic delays till the time allograft failure is advanced and irreversible. Imaging plays a key role in routine surveillance and in management of acute or chronic transplant dysfunction. Multimodality imaging approach is important with ultrasound-Doppler as the first-line imaging study in immediate, early and late post-transplant periods. Additional imaging studies are often required depending on clinical settings and initial ultrasound. Renal functional MRI is a rapidly growing field that has huge potential for early diagnosis of transplant dysfunction. Multiparametric MRI may be integrated in clinical practice as a noninvasive and comprehensive “one-stop” modality for early diagnosis and longitudinal monitoring of renal allograft dysfunctions, which is essential for guiding appropriate interventions to delay or prevent irreversible renal damage. With rapidly increasing numbers of renal transplantation along with improved patient survival, it is necessary for radiologists in all practice settings to be familiar with the normal appearances and imaging spectrum of anatomical and functional complications in a transplant kidney. Radiologist”s role as an integral part of multidisciplinary transplantation team continues to grow with increasing numbers of successful renal transplantation programs across the globe.     

The true clinical significance of renography in nephro-urology

Isotopic renography is a non-invasive technique used routinely by the clinician to provide information about kidney structure and function. Whilst there is no doubt of its value in the accurate measurement of glomerular filtration rate and in the detection of parenchymal abnormalities, its role in the diagnosis of renovascular disease (especially in patients with renal insufficiency), the exclusion of obstruction and the evaluation of the patient with either acute renal failure or renal transplant dysfunction remains unproven. In part, this reflects a failure to standardise protocols and rigorously evaluate diagnostic techniques. Recent developments in ultrasound, computerised X-ray tomography and nuclear magnetic resonance now present the clinician with rival techniques and emphasise the need for the clinical development of isotopic renography.     

Renal carcinoma: duplex Doppler evaluation

Doppler ultrasound has a clearly defined role in the assessment of carotid and peripheral vascular disease. In these situations vessel pathology produces alterations in velocity and volume flow and in the flow-velocity spectrum. Flow in the renal arteries is affected not only by disease of the renal vessels but also by the peripheral resistance to flow within the kidney. Alterations in this peripheral resistance resulting from renal disease are reflected in the Doppler flow spectrum analysis. In 14 patients with renal carcinoma, three different blood flow patterns were observed, reflecting the differing vascularity of the renal tumours. These were compared with blood flow in normal kidneys and in kidneys containing renal cysts. Doppler ultrasound adds further information to the study of renal carcinomas, allowing the prediction of tumour vascularity, and may be useful as a preliminary investigation prior to angiography and embolisation.     

Imaging of unilateral hydronephrosis in an experimental animal model. With special reference to magnetic resonance

In an experimental animal model of partial ureteral obstruction, three different modalities--excretory urography, real-time ultrasound and magnetic resonance--were used for imaging of the unilateral hydronephrotic rabbit kidney. Urography demonstrated well the anatomy of the renal pelvis, the site and the degree of obstruction. Real-time ultrasound and magnetic resonance imaging were both capable of demonstrating compartments of renal parenchyma in addition to the pelveocaliceal dilatation. With magnetic resonance, the renal vessels could be demonstrated. Blood flow velocity in renal arteries and veins was determined with the Doppler technique.     

Ultrasound measured renal length versus low dose CT volume in predicting single kidney glomerular filtration rate

Ultrasound measured renal length and CT measured renal volume are potential surrogate markers for single kidney glomerular filtration rate (SKGFR). The aims of this study are to determine: (1) the repeatability of ultrasound measured length and low radiation dose spiral CT measured volume; (2) the relationship between renal length and volume; and (3) whether length and/or volume is a predictor of SKGFR. 69 patients with suspected renal artery stenosis underwent ultrasound renal length measurement, CT evaluation of renal volume and assessment of SKGFR. 40 patients had ultrasound measurement of length and CT evaluation of volume performed twice on two separate visits. 25 patients also had ultrasound measured renal parenchymal thickness and area. The region of interest was drawn around the kidneys and a threshold set to subtract renal peripelvic fat and renal pelvis. The volume from each slice was summed to obtain the total volume for each kidney. The limits of agreement for ultrasound measured renal length were -1.6 cm to 1.52 cm and that for CT renal volume were -33 ml to 32 ml. There was significant correlation between ultrasound measured length and CT volume (r=0.74, p<0.01). Volume was a better predictor of SKGFR (r(2)=0.57) than length (r(2)=0.48). The combined parameters of ultrasound measured length, area and parenchymal thickness were a better predictor of volume (r(2)=0.81) and SKGFR (r(2)=0.58) than ultrasound measured length on its own. The low dose CT technique was reasonably reproducible and renal volume measurements correlate better with SKGFR than length. Ultrasound predictions of renal volume and SKGFR can be improved by incorporating cross-sectional area and parenchymal thickness. Further investigation is required to refine our low dose CT technique.     

B-scan ultrasound in the evaluation of renal failure.

Twenty-three patients with blood urea nitrogen (BUN) over 70 and thought clinically to be in renal failure were examined by ultrasound. A correct diagnosis of kidney size and the presence or absence of hydronephrosis or polycystic kidney was made in all but one instance. One kidney in a patient with end-stage renal failure was not seen ultrasonically but was subsequently demonstrated on a retrograde pyelogram. In 10 patients, excretory urography (on 4 occasions with tomography) failed to demonstrate the kidneys adequately. It is suggested that ultrasound should either be the first or second imaging technique in the investigation of patients who present in renal failure of unknown cause.     

Evaluation of fetal kidney growth using ultrasound: A systematic review

PurposeTo determine the role of ultrasound imaging in evaluating fetal kidney growth.MethodsMEDLINE, CINAHL and EMBASE databases were electronically searched for studies between 1996 and January 2017 and limited to English language. Studies were included if they reported on an ultrasound technique to assess fetal kidney growth and they were not a case report or case series. There was independent selection of studies by two reviewers in consensus with one other reviewer. Data were extracted by one reviewer in consensus with two other reviewers.ResultsA total of 1785 articles were identified. The full text of 39 of these were assessed for eligibility for inclusion. Twenty-eight studies were then included in the review. Standard two dimensional (2D) fetal renal measurements are easy to perform, however, this review identified that most studies had some methodological limitations. The disadvantage with 2D and three dimensional (3D) fetal renal volumes are that they include the entire kidney and good reproducibility of 3D volumes has not yet been demonstrated. Currently there is limited research on fetal kidney growth in the setting of abnormal fetal growth. Research focussing directly on fetal kidney parenchyma and blood flow is scarce.ConclusionsSome nomograms of 2D and 3D fetal kidney size and volume have been developed. Kidney length is the most popular single fetal kidney measurement; however, it does not seem to be a good indicator of growth. In IUGR fetuses, kidney length remained similar to appropriately grown fetuses whereas AP and TS dimensions were significantly decreased. New ultrasound techniques focusing on the parenchyma of the kidney and perfusion to the kidney should be explored as they may provide more meaningful information on kidney development in the fetus and future kidney function.     

Conventional 15 G needle technique for renal biopsy compared with ultrasound-guided spring-loaded 18 G needle biopsy.

Two techniques for percutaneous renal biopsy were retrospectively reviewed to assess their relative safety and efficacy. Ultrasound localization of the kidney by a radiologists, with subsequent biopsy performed by a renal physician using a hand-held 15 G cutting needle (Tru-Cut), was compared with biopsy performed by a radiologist using an 18 G cutting needle with a spring-loaded biopsy device (Biopty) and real-time ultrasound guidance. The smaller needle with real-time ultrasound is more reliable at retrieving an adequate specimen for histological examination (93%) than the "conventional" technique (79%). Fewer complications occurred in the Biopty group although the difference did not reach statistical significance. The average length of stay in hospital was significantly shorter for elective biopsies with the Biopty device (1.80 compared with 2.93 nights, p less than 0.01). We recommend the use of the Biopty device with an 18 G needle and real-time ultrasound guidance as the method of choice for percutaneous renal biopsy.     

Fractal analysis in radiological and nuclear medicine perfusion imaging: a systematic review

Objectives

To provide an overview of recent research in fractal analysis of tissue perfusion imaging, using standard radiological and nuclear medicine imaging techniques including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) and single-photon emission computed tomography (SPECT) and to discuss implications for different fields of application.

Methods

A systematic review of fractal analysis for tissue perfusion imaging was performed by searching the databases MEDLINE (via PubMed), EMBASE (via Ovid) and ISI Web of Science.

Results

Thirty-seven eligible studies were identified. Fractal analysis was performed on perfusion imaging of tumours, lung, myocardium, kidney, skeletal muscle and cerebral diseases. Clinically, different aspects of tumour perfusion and cerebral diseases were successfully evaluated including detection and classification. In physiological settings, it was shown that perfusion under different conditions and in various organs can be properly described using fractal analysis.

Conclusions

Fractal analysis is a suitable method for quantifying heterogeneity from radiological and nuclear medicine perfusion images under a variety of conditions and in different organs. Further research is required to exploit physiologically proven fractal behaviour in the clinical setting.

Key Points

? Fractal analysis of perfusion images can be successfully performed. ? Tumour, pulmonary, myocardial, renal, skeletal muscle and cerebral perfusion have already been examined. ? Clinical applications of fractal analysis include tumour and brain perfusion assessment. ? Fractal analysis is a suitable method for quantifying perfusion heterogeneity. ? Fractal analysis requires further research concerning the development of clinical applications.     

Needle biopsy of renal allografts: comparison of two techniques

Two techniques for renal allograft biopsy were retrospectively evaluated to compare relative safety and efficacy. After ultrasound (US) localization of the kidney and biopsy with a hand-held 14-gauge cutting needle, an adequate specimen was obtained in 74 of 77 cases (96%). Major complications occurred in six of these 77 cases (8%). One hundred four biopsies were performed by using a smaller 18-gauge cutting needle with a spring-loaded biopsy "gun" and real-time US guidance. With this newer technique, specimens adequate for diagnosis were obtained in 99 biopsies (95%). There was a single major complication with this technique (1%). The 18-gauge needle with real-time US guidance yields comparably adequate specimens with a lower frequency of complications.     

Three-dimensional gadolinium-enhanced magnetic resonance breath-hold FLASH imaging in the diagnosis and staging of renal cell carcinoma

Renal cell carcinoma accounts for 2% of all reported cancers. Its apparent incidence is increasing due to the more widespread use of cross-sectional imaging and as a result, tumours are being detected at an earlier stage. It is hoped that this improvement in early detection will result in a significant increase in survival rates. Radiological diagnosis and staging have a critical role in triaging patients' -treatment. Although computed tomography (CT) and ultrasound are well established in the evaluation of renal cell carcinoma, magnetic resonance (MR) techniques are still rapidly developing. In our institution breath-hold three-dimensional (3D) gadolinium-enhanced fast low-angled single shot (FLASH) spoiled gradient-echo sequence imaging has become an integral part of staging for renal cell carcinoma. In this article, we review our experience of the use of this emerging technique in the diagnosis and staging of renal cancer.     

三维超声成像的临床应用现状与进展

随着超声技术的不断发展，三维超声成像已成为超声医学界关注的热点。与二维超声相比，三维超声能够显示组织结构的立体解剖形态和空间关系，并具有其独特的优势。本文综合文献资料将三维超声图像数据的获取、重建与显示方法加以概括，并将三维超声在临床各个领域对有关疾病的诊断应用与发展前景加以探讨。     

MRI of carotid atherosclerosis

Summary  MRI of carotid atherosclerosis provides a unique method to characterize plaque morphology and tissue composition, as well as, to a certain extent, plaque inflammation. Because of its noninvasiveness, it has many current and potential applications: the fact that it is the only technique that can examine the fibrous cap status in vivo makes it a powerful tool to identify high-risk plaques. With quantitative measurement achievable on a series of plaque compositional and morphologic features, this technique is also well suited for studying atherosclerosis progression and regression. This technique can also be combined with other imaging modalities such as ultrasound and nuclear medicine to create a comprehensive evaluation of carotid atherosclerosis from tissue compliance and composition to inflammation.     

"Scrotal varicocele, exclude a renal tumour". Is this evidence based?

A scrotal varicocele is a common finding during both a scrotal clinical examination or during the course of a scrotal ultrasound examination and invariably found in the left hemiscrotum. Traditionally when a scrotal varicocele is found, the referring clinician requests a renal ultrasound examination or the sonographer extends the examination to include a renal examination; to exclude a retroperitoneal or renal tumour as the cause for the varicocele. The present article examines the relevance of performing the extended ultrasound examination by reviewing the pathophysiological pathways for the development of a varicocele in the presence of a renal or retroperitoneal tumour; the prevalance of co-existing renal or retroperitoneal tumours and a varicocele; and the male population in whom this extended examination may be necessary. The conclusion from available evidence suggests that a retroperitoneal tumour will manifest in other ways before the development of a varicocele, the young patient with a varicocele will almost never have a retroperitoneal tumour, and only when a varicocele develops in an older patient will an extended examination be relevant. Even then it will be a rare finding and there will be other clinical manifestations of the primary tumour.     

Intrathoracic right kidney diagnosed by ultrasound.

Intrathoracic kidneys are rare. A case is described in which the initial intravenous urogram performed for prostatism appeared to show a non-functioning right kidney. A subsequent ultrasound examination revealed that the right kidney was situated in the right hemithorax, well above the liver. Pelvic ectopic kidneys are common and standard teaching is to perform a full length film should an immediate or 5 minute renal area radiograph suggest an absent/non-functioning kidney. With the increasing use of ultrasound in the initial assessment of patients with prostatism, the possible intrathoracic location of a kidney should be remembered when there is failure to demonstrate a kidney in the abdomen or pelvis.     

肾脏核素显像在重复肾畸形诊疗中的应用

重复肾畸形是一种常见的先天性泌尿系统疾病,其诊断多依赖于静脉肾盂造影、超声、CT和MRI等常规影像学手段,这些检查方法各有优缺点。肾脏核素显像检查便利、重复性好、辐射剂量低且安全可靠,可同时对肾脏形态和功能进行评估,在重复肾畸形的诊断、临床决策的制定、疗效评估和预后分析等方面具有很大优势。现今,SPECT/CT已迅速普...     

Renal cell carcinoma: dynamic thin-section CT assessment of vascular invasion and tumor vascularity

Dynamic thin-section computed tomography (CT) was used to evaluate renal cell carcinoma in 80 patients. The lesion was correctly staged with CT in 90% of patients. With use of the dynamic technique, the ipsilateral renal vein was depicted in 99% of patients. Extension of the tumor to the renal vein or the inferior vena cava was correctly detected in 18 of 19 patients. Actual depiction of tumor thrombus was a far more accurate indicator of renal vein invasion than was the identification of isolated renal vein enlargement. Dynamic thin-section CT of the kidney should be considered the routine method for comparison studies with other newer cross-sectional techniques in the evaluation of renal cell carcinoma.