Sameer Deshmukh1, Avinash Kambadakone1, Dushyant V Sahani1, Brian H Eisner2. 1. Departments of Radiology and Urology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts. 2. Departments of Radiology and Urology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts. Electronic address: beisner@partners.org.
Abstract
PURPOSE: We examined renal papillary Hounsfield density in stone formers with all common stone subtypes to further understand the pathophysiology of stone formation. MATERIALS AND METHODS: Using computerized tomography we measured the Hounsfield density of a 0.2 cm(2) renal papillary area in patients with a single renal calyceal stone. Results were compared with those in patients without a nephrolithiasis history who served as controls. Stone composition was determined by stone passage or extraction during endoscopic procedures using infrared spectroscopy and polarized microscopy. We measured the Hounsfield density of the stone bearing calyx and of a single calyx from the upper, middle and lower poles of each kidney. RESULTS: Mean ± SD renal papillary Hounsfield density in controls was 36.2 ± 4.0 HU. In patients with stones Hounsfield density was significantly greater than in controls in stone bearing calyces, nonstone bearing calyces in the affected kidney and calyces in the contralateral nonstone bearing kidney for all stone composition subtypes (range 48.4 to 61.3 HU, each p <0.001). CONCLUSIONS: Patients with kidney stones regardless of composition showed the unique radiographic characteristic of increased renal papillary Hounsfield density. This was true for all calyces and for each kidney in all stone formers with a single renal calyceal stone. This radiographic evidence supports the role of renal papillary deposits or plaques in the pathophysiology of stone formation.
PURPOSE: We examined renal papillary Hounsfield density in stone formers with all common stone subtypes to further understand the pathophysiology of stone formation. MATERIALS AND METHODS: Using computerized tomography we measured the Hounsfield density of a 0.2 cm(2) renal papillary area in patients with a single renal calyceal stone. Results were compared with those in patients without a nephrolithiasis history who served as controls. Stone composition was determined by stone passage or extraction during endoscopic procedures using infrared spectroscopy and polarized microscopy. We measured the Hounsfield density of the stone bearing calyx and of a single calyx from the upper, middle and lower poles of each kidney. RESULTS: Mean ± SD renal papillary Hounsfield density in controls was 36.2 ± 4.0 HU. In patients with stones Hounsfield density was significantly greater than in controls in stone bearing calyces, nonstone bearing calyces in the affected kidney and calyces in the contralateral nonstone bearing kidney for all stone composition subtypes (range 48.4 to 61.3 HU, each p <0.001). CONCLUSIONS:Patients with kidney stones regardless of composition showed the unique radiographic characteristic of increased renal papillary Hounsfield density. This was true for all calyces and for each kidney in all stone formers with a single renal calyceal stone. This radiographic evidence supports the role of renal papillary deposits or plaques in the pathophysiology of stone formation.