Inflammatory Obstruction of the Ureter Caused by Infrarenal Aortitis
A 50-year-old man was admitted to the hospital because of diminished urinary stream and postvoid leakage. The anamnesis was inconspicuous. Sonography revealed dilation of the left ureter with a hydronephrosis grade II. Computed tomography (CT) showed an infrarenal thickening of the aortic wall (Figure 1A and 1B, arrowhead) and proximal vessel wall of the iliaca communis of both arteries (Figure 1C, arrowhead). Furthermore, direct surrounding wall thickening of the vessels obstructed the left ureter (Figure 1C, arrow) with dilation of the proximal left ureter (Figure 1A, arrow). The urography phase of CT confirmed a hydronephrosis grade II (Figure 1D, asterisk).
For further characterization, an (18)F-fluorodeoxyglucose positron emission tomography (PET)–CT of the whole body was performed. The fluorodeoxyglucose PET-CT clearly demonstrated an abnormally intense tracer uptake within the vessel walls of the infrarenal aorta and both proximal arteria iliaca communis (Figures 1E, 1F, 2A, and 2⇓B), which is highly suggestive of mural inflammation such as vasculitis. All other vessels revealed a normal tracer uptake.
The aortitis was indirectly diagnosed by an inflammatory obstruction of the left ureter, which is directly situated lateral to the inflammation-affected aorta. PET-CT images clearly verified nonspecific infrarenal aortitis as a consequence of inflammatory obstruction of the left ureter with a hydronephrosis. Recently, PET-CT has replaced PET, CT, and magnetic resonance imaging in the diagnosis of vasculitis.1 The PET-CT system can draw metabolic and anatomic images in 1 session. PET-CT significantly advances the imaging of morphological abnormalities identified by PET and the definite detection of the pathophysiological uptake of F-fluorodeoxyglucose in organs. Additionally, CT and magnetic resonance imaging frequently revealed discrepancies between laboratory and morphological findings even in patients with decreasing clinical symptoms.1 F-fluorodeoxyglucose uptake in the vessel wall is associated with vasculitis activity and blood inflammatory markers.2 F-fluorodeoxyglucose enhances in inflammation-affected vessel tissue because of the overexpression of glucose transporters and the increased glycolytic metabolism in inflammatory altered tissue.3 Consequently, F-fluorodeoxyglucose is highly sensitive in the detection of vasculitis, especially in patients with local inflammation-affected vessels.