Category: Clinical Stones: Outcomes

MP13-10 - Every millimeter counts: Bone Window NCCT evaluation of kidney stones submitted to RIRS

Fri, Sep 21
2:00 PM - 4:00 PM

Introduction & Objective :

NCCT is able to provide stone features relevant for making clinical decisions. However, the measurements may vary according to the NCCT technique. The aim of this study is to compare kidney stone features between NCCT bone and soft tissue windows in patients submitted to RIRS. 


Methods :

preoperative and 90th postoperative day (POD) NCCT were performed in 92 consecutive symptomatic adult patients (115 renal units) with kidney stone more than 5 mm and less than 20 mm or less than 15 mm in inferior calyx treated by RIRS. NCCT was performed using a 64-slice CT Scanner with a slice thickness of 1 mm and radiation low-dose protocol (low tube charge current – 60 mAs) in patients with BMI < 30 Kg/m2 and standard protocol (160 mAs) in patients with > 30 Kg/m2. NCCT were evaluated in the magnified (400%) bone window (width, 1600 HU/level, 500 HU) and soft tissue window (width, 400 HU/ level, 401 HU) in three axes in a different time by a single radiologist blinded for the measurements of the NCCT other method.


Results :

Stone largest size (7.92±3.81 vs. 9.13±4.08; mm), volume (435.5±472.7 vs. 683.1±665.0; mm3) and density (989.4±330.2 vs. 893.0±324.6; HU) differed between bone and soft-tissue windows, respectively (p<0.0001). Residual fragments diameter after RIRS was not significantly different when evaluated by NCCT using bone or soft tissue windows (p=0.1116). 5.2% of the renal units (6/115) were reclassified from residual fragments > 2 mm on soft tissue window to 0 – 2 mm on bone window.


Conclusions :

Soft tissue window NCCT provides larger stone diameter and volume measurements and smaller density measurements when compared to bone window NCCT. Although bone and soft tissue window NCCT have no significant differences in residual fragments results of RIRS, bone window evaluation may help to avoid reoperation in few cases.

Alexandre Danilovic

Urologist
Department of Urology, Hospital das Clinicas, University of Sao Paulo Medical School, Sao Paulo, Brazil
Sao Paulo, Sao Paulo, Brazil

Bruno Rocha

Radiologist
Department of Radiology, Hospital das Clinicas, University of Sao Paulo Medical School, Sao Paulo, Brazil
Sao Paulo, Sao Paulo, Brazil

Olivier O. Traxer

Professor
Sorbonne Universite, GRC n020 Lithiase Renale, AP-HP, Hospital Tenon, F-75020 Paris, France
Paris, Ile-de-France, France

Fabio Torricelli

Urologist
Department of Urology, Hospital das Clinicas, University of Sao Paulo Medical School, Sao Paulo, Brazil
Sao Paulo, Sao Paulo, Brazil

Giovanni Marchini

Urologist
Department of Urology, Hospital das Clinicas, University of Sao Paulo Medical School, Sao Paulo, Brazil
Sao Paulo, Sao Paulo, Brazil

Eduardo Mazzucchi

Head of Endourology Section
Department of Urology, Hospital das Clinicas, University of Sao Paulo Medical School, Sao Paulo, Brazil
Sao Paulo, Sao Paulo, Brazil

Miguel Srougi

Head of Department of Urology
Department of Urology, Hospital das Clinicas, University of Sao Paulo Medical School, Sao Paulo, Brazil
Sao Paulo, Sao Paulo, Brazil