The role of computed tomography in modern paediatric uroradiology

Local behavior and lymph node metastases of Wilms' tumor: accuracy of computed tomography

Objective To evaluate the accuracy of computed tomography for local and lymph node staging of Wilms' tumor. Materials and Methods Each case of Wilms' tumor was evaluated for the presence of abdominal lymph nodes by a radiologist. Signs of capsule and adjacent organ invasion were analyzed. Surgical and histopathological results were taken as the gold standard. Results Sensitivity was 100% for both mesenteric and retroperitoneal lymph nodes detection, and specificity was, respectively, 12% and 33%, with positive predictive value of 8% and 11% and negative predictive value of 100%. Signs of capsular invasion presented sensitivity of 87%, specificity of 77%, positive predictive value of 63% and negative predictive value of 93%. Signs of adjacent organ invasion presented sensitivity of 100%, specificity of 78%, positive predictive value of 37% and negative predictive value of 100%. Conclusion Computed tomography tumor showed low specificity and low positive predictive value in the detection of lymph node dissemination. The absence of detectable lymph nodes makes their presence unlikely, and likewise regarding the evaluation of local behavior of tumors.

Magnetic resonance and computed tomography in pediatric urology: an imaging overview for current and future daily practice

The main imaging modality of the urinary tract in children is ultrasound. When further cross-sectional morphologic examination and/or functional evaluation is required, magnetic resonance (MR) imaging is the logical and optimal second step, particularly in pediatric patients. There are two main exceptions to this. The first one is when after an ultrasound, additional diagnostic imaging for urolithiasis is needed. The second one involves severe polytrauma, including blunt abdominal trauma. In this review, an overview of the MR imaging and computed tomography examinations important for current and future daily pediatric uroradiologic practice is presented.

Prenatal sonographic diagnosis of mature renal teratoma: a case report

Renal teratoma is an extremely rare condition found in adolescents and young adults. Here, we report a case in which renal teratoma was diagnosed by fetal ultrasound examination. To our knowledge, this is the first report to describe the imaging manifestation of renal teratoma in prenatal diagnosis.

Pediatric uroradiology: state of the art

Recent years have witnessed major strides in imaging modalities, including US and contrast-enhanced voiding urosonography, fluoroscopy, CT and MRI, and these have significantly impacted paediatric uroradiology. The trend is towards reduced or no radiation exposure and combined morphological and functional imaging. This review presents the currently available and recommended modalities in modern paediatric uroradiology practice.

Imaging of the neonatal genito-urinary tract

OBJECTIVE

To describe imaging of typical conditions and diseases in the neonatal genito-urinary (GU) tract.

METHOD

The use, the applications, and typical findings using standard imaging techniques (e.g., ultrasound, US, voiding cystourethrography, VCUG) are described, with emphasis on technical aspects, indications, and restrictions in neonatal queries. Only basic applications as used in routine clinical work are included, other more sophisticated and advanced imaging techniques such as scintigraphy, MR-urography, genitography or image-guided interventional procedures will only briefly be mentioned.

SUMMARY AND CONCLUSION

Conventional imaging methods are valuable and - particularly in the neonatal GU tract - sometimes irreplaceable. Skillfully used basic imaging techniques, particularly of US (including modern methods such as Doppler sonography, Harmonic imaging or contrast enhanced US), supplemented by fluoroscopy for VCUG can answer most acutely treatment relevant queries. Rarely early scintigraphic studies, genitography, or MRI may become indicated, usually not for establishing the diagnosis, but to collect additional (functional or anatomical) information necessary for deciding on further treatment, or even image guided interventional procedures may become necessary.

[Modern imaging technology for childhood urinary tract infection]

Imaging in childhood urinary tract infection (UTI) is still a matter of debate. There are established guidelines, however new knowledge and the changed medical environment have enhanced this ongoing discussion. These new insights have impacted therapy and consequently the imaging algorithm. Modern imaging methods -- particularly MRI and modern ultrasound (US) -- are less invasive with a lower radiation burden. Additionally, it has been shown that VUR is a poor predictor for renal scarring out, which affects long-term results. Furthermore, the majority of UT malformations is depicted by prenatal US. The most crucial aspect of improving long-term outcome appears to be the early and reliable depiction of UTI and effective treatment to prevent renal scarring. This review tries to present this new knowledge and to discuss the potential of modern imaging. Recent changes in imaging algorithms are highlighted and an outcome-oriented algorithm that addresses these recent developments is proposed, without lightly abandoning established standards. It consists of an orienting US and -- for depiction of renal involvement -- amplitude coded color Doppler sonography or renal static scintigraphy (considered the gold standard, particularly for evaluating scars); in future MRI may play a role. Based on this concept, only patients with renal damage as well as patients with complex urinary tract malformations or intractable recurrent UTI may have to undergo VCUG.

Dose reduction in multidetector CT of the urinary tract. Studies in a phantom model

A novel ureter phantom was developed for investigations of image quality and dose in CT urography. The ureter phantom consisted of a water box (14 cm x 32 cm x 42 cm) with five parallel plastic tubes (diameter 2.7 mm) filled with different concentrations of contrast media (1.88-30 mg iodine/ml). CT density of the tubes and noise of the surrounding water were determined using two multidetector scanners (Philips MX8000 with four rows, Siemens Sensation 16 with 16 rows) with varying tube current-time product (15-100 mAs per slice), voltage (90 kV, 100 kV, 120 kV), pitch (0.875-1.75), and slice thickness (1 mm, 2 mm, 3.2 mm). Contrast-to-noise ratio as a parameter of image quality was correlated with dose (CTDI) and was compared with image evaluation by two radiologists. The CT densities of different concentrations of contrast media and contrast-to-noise ratio were significantly higher when low voltages (90 kV versus 120 kV, 100 kV versus 120 kV) were applied. Smaller slice thickness (1 mm versus 2 mm) did not change CT density but decreased contrast-to-noise ratio due to increased noise. Contrast phantom studies showed favourable effects of low tube voltage on image quality in the low dose range. This may facilitate substantial dose reduction in CT urography.

Solitary pulmonary metastasis presenting 20 years after primary resection of Wilms tumor

Wilms tumor is the most common renal malignancy of childhood. Relapse occurs most often within 4 years of initial diagnosis, and the most common site of metastasis is the lung. We describe a 22-year-old man who presented with hemoptysis and a solitary pulmonary lesion 20 years after primary resection of Wilms tumor. Computed tomography of the chest showed an indeterminate pulmonary mass of heterogeneous attenuation with no other intrathoracic abnormalities. Surgical resection revealed a solitary pulmonary metastasis from Wilms tumor. Further evaluation yielded no evidence of extrathoracic metastases. This case shows that late relapse in the form of a solitary pulmonary mass can occur in patients with Wilms tumor.

[Management of abdominal trauma in children]

Management of abdominal trauma in children has considerably changed over the last fifteen years. This is mainly due to advances in imaging techniques combined with a more conservative approach. Non-surgical management is frequently preferred with close clinical and biological surveillance, in addition to comprehensive imaging evaluation. The imaging work up must be adapted to this conservative approach. The increasing availability of helical CT technology and Doppler US imaging can be used to advantage in the evaluation of these patients. Euratom Directive 97-43 identifies children as a particular subgroup of patients with regards to exposure to ionizing radiation thus requiring us to reconsider the routine use of CT in this patient subpopulation and promoting the use of alternate imaging techniques. Based on a review of the literature as well as our own experience, where we currently favor US with selective use of CT, the advantages and pitfalls of each imaging technique will be reviewed. Ultimately, the imaging protocol for each patient should be based on availability, expertise, and individual clinical setting.

Imaging of renal tumours in infancy and childhood

There is a large range of benign and malignant renal neoplasms. This article lists the most benign, indeterminate and malignant renal tumours that occur during infancy and childhood. It briefly describes the most important entities, including their imaging features, and important complications. Differential diagnosis and pitfalls are discussed, and a brief suggestion for a standardised imaging algorithm is proposed. Although modern imaging techniques, including colour Doppler sonography, helical or multidetector CT, and MR have significantly improved imaging potential, the definite diagnosis on tumour entity still is established only by histology.