Nuclear Medicine in Pediatric Nephro-Urology: An Overview.

In the context of ante-natally diagnosed hydronephrosis, the vast majority of children with a dilated renal pelvis do not need any surgical treatment, as the dilatation resolves spontaneously with time. Slow drainage demonstrated at Tc-99m-mercaptoacetyltriglycine (MAG3) renography does not necessarily mean obstruction. Obstruction is defined as resistance to urinary outflow with urinary stasis at the level of the pelvic-ureteric junction (PUJ) which, if left untreated, will damage the kidney. Unfortunately this definition is retrospective and not clinically helpful. Therefore, the identification of the kidney at risk of losing function in an asymptomatic patient is a major research goal. In the context of renovascular hypertension a DMSA scan can be useful before and after revascularisation procedures (angioplasty or surgery) to assess for gain in kidney function. Renal calculi are increasingly frequent in children. Whilst the vast majority of patients with renal stones do not need functional imaging, DMSA scans with SPECT and a low dose limited CT can be very helpful in the case of complex renal calculi. Congenital renal anomalies such as duplex kidneys, horseshoe kidneys, crossed-fused kidneys and multi-cystic dysplastic kidneys greatly benefit from functional imaging to identify regional parenchymal function, thus directing further management. Positron emission tomography (PET) is being actively tested in genito-urinary malignancies. Encouraging initial reports suggest that F-18-fluorodeoxyglucose (FDG) PET is more sensitive than CT in the assessment of lymph nodal metastases in patients with genito-urinary sarcomas; an increased sensitivity in comparison to isotope bone scans for skeletal metastatic disease has also been reported. Further evaluation is necessary, especially with the promising advent of PET/MRI scanners. Nuclear Medicine in paediatric nephro-urology has stood the test of time and is opening up to new exciting developments

Diagnosis and long-term outcome of renal cysts after laparoscopic partial nephrectomy in children

To document the imaging follow-up of laparoscopic partial nephrectomy (LPN) in children and to investigate the natural history of cystic lesions following LPN. PATIENTS AND METHODS: We reviewed the ultrasonography (US) imaging reports performed during the follow-up of 125 children (77 girls, 48 boys; mean age 3.2 years) who underwent LPN in two centres of paediatric surgery in the period 2005-2015. RESULTS: A transperitoneal approach was adopted in 83 children and a retroperitoneal approach in 42. The mean follow-up was 4.2 years. At US, an avascular cyst related to the operative site was found after 61/125 procedures (48.8%). As for their appearance, 53/61 cysts were simple and anechoic, and eight of the 61 cysts appeared septated. The mean diameter of the cysts was 3.3 × 2.8 cm. As for their course, 13/61 cysts (21.3%) disappeared after a mean of 4 years, 26/61 (42.6%) did not significantly change in dimension, 17/61 (27.8%) decreased in size, and only five of the 61 cysts (8.3%) enlarged. The cysts were asymptomatic in 51 children (83.6%), while they were associated with urinary tract infections (UTIs) and abdominal pain in the remaining 10; none required a re-intervention. CONCLUSIONS: The US finding of a simple cyst at the operative site after LPN is common during follow-up, with an incidence of ~50% in our series. In regard to aetiology, probably a seroma takes the place of the removed hemi-kidney. There was no correlation between cyst formation and type of surgical technique adopted. As there was no correlation between cysts and clinical outcomes, renal cysts after LPN can be managed conservatively, with periodic US evaluations