Potential applications of three-dimensional ultrasound in the pediatric urinary tract: pictorial demonstration based on preliminary results

Abstract

The aim of this study was to describe the potential of three-dimensional ultrasound (3DUS) in the urinary tract of neonates, infants, and children. The potential applications are illustrated based on our experience in 80 patients using two different 3DUS techniques. Various disease entities throughout the neonatal and pediatric age have been evaluated. The potential of 3DUS is discussed based on comparison with conventional 2DUS or other imaging (as clinically indicated), focused on the potentially improved renal parenchymal volume assessment. In our experience, 3DUS is feasible in neonates, infants, and children without sedation. It reduces imaging time, improves demonstration of complex anatomy and allows for evaluation of anatomy/pathology in any plane. The 3DUS improves volume assessment and follow-up comparison by offering an improved standardization and documentation. Rendered views of the dilated collecting system enable a comprehensive demonstration of hydronephrosis similar to intravenous urography or MR urography images. Additionally, 3DUS offers an ideal tool for training and education. Yet, limitations have to be acknowledged: areas inaccessible for 2DUS; poor quality of the original 2DUS acquisition; limited resolution; patient motion and breathing; cardiac pulsation creating artifacts and misregistration; equipment cost; lack of 3D DICOM standards creating problems with data storage; as well as system-inherent technical limitations. Nevertheless, the 3DUS holds the potential to become a valuable additional imaging tool for sonographic evaluation of the pediatric urinary tract.

Potential role of 3DUS in infants and children

“…In the kidney, the superior potential of 3DUS for volume assessment of structures with more complicated shape has been utilized to accurately calculate renal parenchymal volume, which is most helpful in hydronephrotic kidneys [8,17,20,21]. This is achieved by subtraction of the segmented dilated collecting system from the overall kidney volume (Fig.…”

“…This rendered inverted view of the dilated system is also helpful for visualization of the pelvicalyceal-ureter unit, which aids in differentiating non-obstructed dilatation in malformed calices, such as megacalicosis, from the typical ballooned shape of an obstructive dilated system. It can also be helpful for assessment of caliceal diverticuli and tertiary calices [8,17]. The same principle of volume assessment may apply to tumor volume calculation, which is potentially beneficial for following patients with renal or bladder tumors during chemotherapy (Fig.…”

“…Other small-part applications, besides improved volume calculations, are investigation of musculoskeletal structures, and skin and soft-tissue lesions, where 3DUS may be valuable are in conditions where an additional reconstructed plane that is not accessible by conventional US offers crucial information, or for very torturously shaped abnormalities [1,2,8,17,[28][29][30]. This may prove helpful in fractures that sometimes can be difficult to see on plain film, or for abscesses with fistula formation [8,17,31].…”

“…It was initially used for gynecologic and obstetric imaging; other applications in adults followed [1][2][3][4][5]. With the introduction of transducers that are useful in children, the first efforts have been undertaken to evaluate its potential in pediatric imaging [6][7][8][9][10][11][12]. This review will (1) present basic methodical aspects of 3DUS to enable an understanding of the underlying physics with its implications for scan technique and results, (2) present some of our local experience, and (3) review the literature.…”

Patient and Probe Tracking During Freehand Ultrasound

“…Although sometimes used to reduce the errors caused by respiration, breath holds and respiratory gating are not always feasible solutions as some people, especially young children [15], and sick patients would have difficulties holding their breath. Remaining still may be difficult due to arthritis in the neck, back, or shoulders [5].…”