Three‐dimensional assessment of urinary stone on non‐contrast helical computed tomography as the predictor of stonestreet formation after extracorporeal shock wave lithotripsy for stones smaller than 20 mm

Abstract

Abstract:The incidence of stonestreet formation after extracorporeal shock wave lithotripsy (ESWL) rises with increasing stone burden. However, stonestreet after ESWL is often experienced even in stones smaller than 20 mm. To examine whether the non-contrast helical computed tomography (CT) data could predict stonestreet formation in these stones, 53 radiopaque stones of 5-20 mm treated with ESWL were evaluated. Maximal dimension was measured on plain radiograph. From an attenuation value histogram graphed from the CT data, total stone volume and mean attenuation value were calculated. Seven stonestreets longer than 25 mm developed. There was no significant difference in maximal dimension and total stone volume between stones that did and stones that did not develop stonestreet. Mean attenuation value was the sole significant predictive factor. Application of mean attenuation value with cut-off level of 650 HU would anticipate stonestreet formation with a sensitivity of 85.7% and a specificity of 71.7%. The estimated risk of stonestreet formation is high in the treatment of stones with higher mean attenuation value.

New and Evolving Concepts in the Imaging and Management of Urolithiasis: Urologists’ Perspective

“…Novel semiautomatic segmentation tools can also be used to estimate stone volume. Stone volume has been shown to be valuable for preoperative planning, and it is often useful to perform both linear and volumetric measurements of stone burden (27,47,48). In addition to being key to appropriate treatment planning, stone burden assessment can also be used to predict treatment success, particularly for procedures such as SWL (47,48).…”

“…Measuring the stone volume eliminates this problem because it takes into account the shape and diameter (in all dimensions) of the stone (27). Various authors have used different methods to calculate stone volume and hence to estimate stone burden, such as electronically tracing the stone circumference on all stone-bearing images to generate a three-dimensional volume measurement, or using the product of three orthogonal measurements (27,47,48). Novel semiautomatic segmentation tools can also be used to estimate stone volume.…”

“…High-resolution coronal reformatted images generated automatically from isotropic data sets obtained with 16-64-detector CT allow more rapid and accurate detection of urinary stones than do axial images alone (45,46). The quantification of stone burden with volumetric techniques, made feasible by the near-isotropic resolution of multidetector CT, holds great promise as both a tool for surgical planning and a predictor of treatment response (27,47,48). In addition, multidetector CT helps in the assessment of stone fragility and composition with use of attenuation measurements and characterization of internal structure (49)(50)(51)(52)(53).…”

“…Stone volume has been shown to be valuable for preoperative planning, and it is often useful to perform both linear and volumetric measurements of stone burden (27,47,48). In addition to being key to appropriate treatment planning, stone burden assessment can also be used to predict treatment success, particularly for procedures such as SWL (47,48). Wang et al (47) showed that a stone burden of more than 700 mm 3 as determined from the product of the three spatial dimensions is a significant predictor of failure for SWL.…”

Taş Hastalarının Çağdaş Radyolojik Yöntemlerle Değerlendirilmesi ve Ufuktaki Yeni Görüntüleme Yöntemleri

“…Bunlar arasında taş çevresinin elektronik olarak işaretlenme-si, 3 boyutlu hacim ölçümü ve yeni yarı otomatik segmentasyon yöntemleri bulunur. Bir çalışmada 700 mm 3 'ün üzerınde hacme sahip taşların ESWL den fayda görmeyeceği gösteril-miştir (20,21).…”