Nutcracker phenomenon: A new diagnostic method of multislice computed tomography angiography

Objective: We evaluated 3-D computed tomography angiography (3-D CTA) in the diagnosis of the nutcracker phenomenon, and its significance in postoperative follow up. Patients and Methods: Three-dimensional CTA was used to compare the anatomical relations of the left renal vein with the aorta and the superior mesenteric artery in patients with the nutcracker phenomenon and in a control group. Four patients with the nutcracker phenomenon received a surgical procedure of the transposition of the left renal vein. The 3-D CTA was used for all patients during postoperation follow-up testing. Results: The 3-D CTA showed a compression of the left renal vein between the aorta and the superior mesenteric artery (SMA) and the abnormal acute angle between them. The angles and distances between the SMA and the aorta were 39.3 +/- 4.3 degrees and 3.1 +/- 0.2 mm in the patient groups and 90 +/- 10 degrees and 12 +/- 1.8 mm in the control groups, respectively. Differences in angles and distances were statistically significant between the two groups (P < 0.05). Surgical transposition of the left renal vein was performed successfully. Postoperative 3-D CTA revealed the distance between the SMA and the aorta was nearly normal. Conclusion: The reconstruction imaging of the renal vein by means of 3-D CTA revealed that unusual hematuria was due to compression of the left renal vein; therefore it may be a useful alternative imaging technique instead of conventional examinations. The non-invasive 3-D CTA may be a useful tool in the diagnosis of the nutcracker phenomenon and follow-up testing.