Added value of SPECT/CT for the evaluation of obstructive uropathy

Objectives: Single photon emission computed tomography (SPECT)/computed tomography (CT) is becoming widely used in daily nuclear medicine practice. However, the application SPECT/CT in renal disease has rarely been reported. The aim of this study is to evaluate the added value of hybrid SPECT/CT in evaluation of obstructive uropathy with both renal scintigraphy/SPECT and noncontrast CT. Methods: 47 patients with a diagnosis of unilateral or bilateral hydronephrosis on ultrasound were underwent renal scintigraphy in combination with SPECT/CT, including 20 males 27 females, aged 67.1±7.2 years. 99mTcdiethylenetriaminepentacetic acid (DTPA) was administered intravenously followed by renal scintigraphy (dynamic planar imaging). Immediately after that a renal SPECT/CT was performed. The CT scan was performed with a low mA protocol. A retrospective analysis was performed to assess the performance scintigraphic and CT assessments as well as the added value of a combined SPECT/CT compared with solo SPECT and solo noncontrast helical CT respectively. Results: All 47 patients show radiotracer retention in the renal collecting system with or without a hydroureter on both renal scintigraphy and SPECT. This is associated with a retention pattern of renogram curve, which may represent either nonobstructive or obstructive hydronephrosis. Impaired renal function was also demonstrated in all affected kidneys in varying degrees. The CT component of the SPECT/CT demonstrates added value for the study including severity of dilatation of renal collecting system and ureter and the possible obstructive causes, ie, stones (41 patients), malignant disease involving ureter (3 patients), postsurgical changes of the kidney or ureter (3 patients). This is better demonstrated on the fusion SPECT/CT images. In addition, the 3 patients with malignancy involving the ureters also show impaired renal function in their contralateral kidneys, which were not aware before study. Conclusion: Combination of traditional 99mTcDTPA renal dynamic scintigraphy and renogram with SPECT/CT could provide not only anatomical and functional information of kidneys and ureters in the evaluation of obstructive uropathy and may also show the causes of the disease. Our study indicated that the added value of a simultaneous CT imaging renal scintigraphy and SPECT had a clear added value of confidence in daily clinical practice.