Diagnostic accuracy of the jetting sign and a dilatation ratio of left renal vein in CT urography for detecting anterior nutcracker syndrome

Abstract

To investigate the diagnostic value of computed tomography (CT) urography findings of anterior nutcracker syndrome (NCS). The study included patients with left renal vein (LRV) compression at the aortomesenteric portion at CT urography who underwent renal venography or cystoscopy. Patients with a renocaval pressure gradient of ≥3 mmHg on renal venography or bloody urine jetting from the left ureteral orifice on cystoscopy were defined as the NCS group; the remaining patients comprised the non-NCS group. CT findings were analysed using the jetting of contrast medium flow from the LRV to the inferior vena cava (jetting sign), aortomesenteric distance, presence of collateral veins, and a dilatation ratio of LRV diameter at the aortomesenteric portion (arterial phase/delayed phases). Clinical findings, including age, gender, and body-mass-index, were also analysed. CT features and clinical findings were compared between the NCS and non-NCS groups. Diagnostic performance of CT parameters was assessed using receiver operating characteristic curve analysis. A total of 70 patients (21 men, mean age 44.4±17.2 years) with NCS (n=13) and non-NCS (n=57) were included. Younger age (<40 years), presence of the jetting sign, and a lower dilatation ratio of LRV diameter between the arterial and delayed phases (<1.7) were found to be significant independent factors for predicting the NCS group (OR 24.5, 18.9, 19.4, respectively, p<0.05 for all). The combination of the presence of the jetting sign and a dilatation ratio of LRV diameter of <1.7 obtained the highest AUC of 0.88. The jetting sign and the dilatation ratio of LRV diameter between the arterial and delayed phases can both be very useful in the diagnosis of anterior nutcracker syndrome during CT urography.