Przemysław Bombiński

Lower-dose CT urography (CTU) with iterative reconstruction technique in children – initial experience and examination protocol

Summary Background Conventional X-ray urography is one of the basic imaging techniques in urinary tract diseases in children. CT urography (CTU) employing standard Filtered Back Projection (FBP) reconstruction algorithms is connected with higher radiation dose. Advanced iterative reconstruction techniques enable lowering the radiation dose to the level comparable with conventional X-ray urography with better visualization of the urinary tract. Study protocol and indications for this modified technique should be discussed. Material/Methods Introduction of iterative image reconstruction techniques allowed to significantly reduce the radiation dose delivered during examinations performed at our Department, including CT examinations of urinary tract in children. During the last two years, CT urography replaced conventional X-ray urography and became the basic imaging technique in our Department. We discuss the study protocol regarding pediatric CTU examinations. The main goal is to receive an optimal image quality at reduced radiation dose. Results CTU examinations performed using the standard filtered back projection (FBP) reconstruction technique are associated with radiation doses about 1.5 times higher than those in conventional X-ray urography. Implementation of iterative reconstruction algorithms in advanced CT scanners allow to reduce the radiation dose to a level comparable or even lower than that in X-ray urography. In addition, urinary tract can be evaluated more precisely in multiplanar reformatted (MPR) and volume rendered (VR) images. Conclusions 1. Advanced iterative reconstruction techniques allow to reduce radiation dose in CT examinations and to extend indications for CT urography in children. 2. Urinary tract can be evaluated more precisely in multiplanar reformatted and volume rendered images. 3. CTU may replace conventional X-ray urography in children.

Ultrasonography of Extravaginal Testicular Torsion in Neonates.

Summary Background Extravaginal testicular torsion (ETT), also called prenatal or perinatal, occurs prenatally and is present at birth or appears within the first month of life. It has different etiology than intravaginal torsion, which appears later in life. Testicular torsion must be taken into consideration in differential diagnosis of acute scrotum and should be confirmed or ruled out at first diagnostic step. Ultrasonography is a basic imaging modality, however diagnostic pitfalls are still possible. There is still wide discussion concerning management of ETT, which varies from immediate orchiectomy to conservative treatment resulting in testicle atrophy. Material/Methods In this article we present ultrasonographic spectrum of ETT in neonates, which were diagnosed and treated in our hospital during the last 8 years (2008–2015), in correlation with clinical and intraoperative findings. Results Thirteen neonates with ETT were enrolled in the study – 11 patients with a single testicle affected and 2 patients with bilateral testicular torsion. Most common signs on clinical examination were: hardened and enlarged testicle and discoloration of the scrotum. Most common ultrasonographic signs were: abnormal size or echostructure of the affected testicle and absence of the blood flow in Doppler ultrasonography. In 3 patients ultrasound elastography was performed, which appeared very useful in testicle structure assessment. Conclusions Testicular torsion may concern boys even in the perinatal period. Ultrasonographic picture of acute scrotum in young boys may be confused. Coexistence of the abnormal size or echostructure of the torsed testicle with absence of the blood flow in Doppler ultrasonography appear as very specific but late ultrasonographic sings. Ultrasound elastography may be a very useful tool for visualisation of a very common clinical sign – hardening of the necrotic testicle.

Hepatic Portal Venous Gas in Children Younger Than 2 Years Old – Radiological and Clinical Characteristics in Diseases Other Than Necrotizing Enterocolitis

Summary Background Hepatic portal venous gas (HPVG) is a rare imaging finding in children. It can be an important manifestation of severe diseases such as necrotizing enterocolitis (NEC) in neonates or bowel wall rupture in older children. However, there are many other diseases presenting with HPVG that do not necessarily require a surgical intervention. Case Report In the period between 2011–2015, there were 12 cases of HPVG in children aged up to 24 months in our hospital. We did not include children with NEC. We retrospectively analyzed clinical data and US examinations as regards the suspected causes and final diagnoses. Only 1 patient with HPVG required an immediate surgical intervention. This was – a 4-month-old girl 32 days after a repair of a congenital diaphragmatic hernia, with ultrasound signs of acute bowel wall necrosis. During surgery a bowel strangulation was revealed. Other causes included: – 4 patients with bowel inflammation (including complications of neoplastic diseases such as leukemia and Hodgkins’disease); – 3 patients with food allergy; – 1 patient with acute gastroenteritis; – 1 patient with hepatic injury because of a suspected metabolic disease; – 1 incidental finding revealed before closing a ventricular septum defect; – 1 patient during follow-up performed 2 weeks after a reconstruction of bowel continuity. Conclusions HPVG is not always a sign of a life-threatening condition and it should not be by itself an indication for surgical treatment. HPVG requires a close monitoring of the clinical status, which is crucial for further management. In patients in non-severe clinical condition, we propose to perform a follow-up ultrasound imaging within 1–2 days, and not to extend diagnostic procedures, especially in case of ultrasound picture normalization. An abdominal ultrasound examination appears to be the method of choice for the identification of gas in the hepatic portal system in children.

Calyceal Diverticulum of the Kidney – Diagnostic Imaging Dilemma in Pediatric Patients – Case Report

Summary Background Calyceal diverticula are rarely diagnosed in children. They can mimic other renal cystic lesions and correct diagnosis can be difficult to establish. Connection between fluid collection and collecting system confirmed by imaging studies is the key diagnostic finding. Case Report In this report we present a case of pediatric patient with calyceal diverticulum, with initial ultrasonographic diagnosis of simple renal cyst. Final diagnosis was established after extended diagnostics following infection of a fluid collection. Conclusions 1. Differential diagnosis of well-circumscribed solitary renal fluid collections in children should include particularly: simple cyst, calyceal diverticulum and the first demonstration of ADPKD. 2. Diagnosis of calyceal diverticulum should be confirmed by contrast studies. 3. Standard management of calyceal diverticula in children includes ultrasonographic follow-up and conservative treatment and rarely requires surgical intervention.

Computed tomography urography with iterative reconstruction algorithm in congenital urinary tract abnormalities in children – association of radiation dose with image quality

Purpose To assess the extent to which a radiation dose can be lowered without compromising image quality and diagnostic confidence in congenital urinary tract abnormalities in children by using a CT scanner with an iterative reconstruction algorithm. Material and methods 120 CT urography image series were analysed retrospectively. Image series were divided into four study groups depending on effective radiation dose (group 1: 0.8-2 mSv; group 2: 2-4 mSv; group 3: 4-6 mSv; group 4: 6-11 mSv). Objective and subjective image quality were investigated. In objective analysis, measurements of attenuation and standard deviation (SD) in five regions of interest (ROIs) were performed in 109 excretory image series, and image noise was evaluated. In subjective analysis, two independent radiologists evaluated 138 kidney units for subjective image quality and diagnostic confidence. Results There were no significant differences in image noise in objective evaluation between the following study groups: 2 vs. 3 and 3 vs. 4 in all ROIs (with the only exception in spleen SD measurement between study groups 2 vs. 3), while there was significantly more image noise in group 2 in comparison to group 4. For all other ROIs in all study groups, there was more image noise on lower dose images. There were no significant differences in pairwise comparisons between study groups in subjective image quality. Diagnostic confidence was not significantly different between all study groups. Conclusions Low-dose CT urography can be a valuable method in congenital urinary tract abnormalities in children. Despite poorer image quality, diagnostic confidence is not significantly compromised in examinations performed with lower radiation doses.

Congenital posterior urethral diverticulum in an infant with Robinow syndrome – diagnostic difficulties

Congenital posterior urethral diverticulum (PUD) is a rare congenital anomaly. Proper diagnosis and treatment in such cases still is challenging. More common are acquired diverticula of the posterior urethra, which mostly follow surgical repair of imperforate anus. We report a case of a large, congenital PUD which was diagnosed in a 3-month old boy with very rare genetic disorder Robinow syndrome, as a result of bladder catheterization difficulties before cardiac surgery. There was no previous history of voiding problems or urinary tract infections. External genital abnormalities are typical clinical findings in children with Robinow syndrome, as it was in presented patient. Imaging studies showed large PUD. The described case shows than even large PUD may be primarily asymptomatic and its diagnosis is somewhat difficult. Correspondence to: Stanislaw Warchol PhD, MD, Department of Pediatric Surgery and Urology, Medical University of Warsaw, 02-91 Zwirki and Wigury street, Warsaw, Poland, Tel. (48) 606 189 852 / ( 48 22) 3179746, E-mail: swarchol@poczta.onet.pl