Category: New Technology: Stones

MP5-7 - Hounsfield density for discrimination of pure and mixed calcium oxalate mono- and di- hydrate stones: preliminary results

Fri, Sep 21
10:00 AM - 12:00 PM

Introduction & Objective : Computed Tomography (CT) is the gold standard for the diagnosis and treatment planning of stones. However, there is no proven method to differentiate calcium oxalate mono- (CaOxMH) from di- hydrate (CaOxDH) stones. The aim of this study is to evaluate the predictive value of Hounsfield (HU) parameters on CT scan for the discrimination of CaOxMH and CaOxDH.


Methods :

Data from 107 patients submitted to percutaneous or endoscopic lithotripsy between November 2010 and April 2017 were retrospectively analyzed. Inclusion criteria were: I-II) the availability of a pre-operative CT-scan and the stone biochemical analysis, III) a maximum stone diameter > 4 mm, IV) a calcium oxalate stone component > 50%. Group A (CaOxMH) and B (CaOxDH) included 81 and 26 patients, respectively. Pure stones were defined as single stone component > 75% (group A: 59 vs group B: 18). All images were reviewed by a single urologist, blinded to the composition of the calculi. Stone volume, HU mean (HUM) value, core (HUC) and periphery (HUP) HU values and their absolute difference (deltaHU) were evaluated. HU density (HUD) was defined as the ratio between mean HU and the stone’s largest diameter. Demographics and clinical data were evaluated using descriptive statistics. Receiver Operating Characteristic (ROC) curves were calculated to test the predictive power of HU parameters to differentiate the two groups<./p>


Results : Demographic and clinical data are reported in table 1. CaOxMH and CaOxDH stones differed in terms of HUD (mean ± SD 86,7 ± 36,1 vs 64,2 ± 27,4; p=0,004) and HUC (p=0,03). HUD best differentiated the two groups (cut-off 70 HU/mm; specificity 62%, sensitivity 65%). The AUC of HUD was 0,66. In case of HUD > 70 HU/mm probability of CaOxDH was three folds higher. Regarding pure stones, the accuracy of HUD improved (86,8 ± 34,8 vs 62,4 ± 27, p=0,008; specificity 64%, sensitivity 72%) at the same cut-off. 


Conclusions : HUD is the best variable to distinguish either mixed or pure calcium oxalate stones. These findings could help the clinician to select the best candidates to SWL treatment.

Matteo Fontana

Resident
Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milan, Lombardia, Italy

Andrea Gallioli

Resident
Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milan, Lombardia, Italy

Elisa De Lorenzis

Resident
Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milan, Lombardia, Italy

Luca Boeri

Resident
Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milano, Lombardia, Italy

Luca Boeri MD, Resident in Urology, IRCCS Fondazione Ca' Granda, Ospedale Maggiore Policlinico, University of Milan, Milan, Italy.
I am a III year resident in Urology (chief Prof. Emanuele Montanari). I have been doing research since 4 years. My interests are in minimally invasive surgery, endourology, stone disease, infections, prostate cancer, bladder cancer and andrology.
I am currently attending a 1 year Research Fellowship at Mayo Clinic (Rochester, Minnesota, USA).
Our Department in Milan is a leading center for PCNL, RIRS, UTUC treatment, robotic surgery.

Stefano Paolo Zanetti

Resident
Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milan, Lombardia, Italy

Franco Palmisano

Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milan, Lombardia, Italy

Gianluca Sampogna

Resident
Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milan, Lombardia, Italy

Fabrizio Longo

Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milan, Lombardia, Italy

Emanuele Montanari

Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Department of Clinical Sciences and Community Health, University of Milan, Urology, Milan, Italy
Milan, Lombardia, Italy