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

Abstract

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° and 3.1 ± 0.2 mm in the patient groups and 90 ± 10° 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.

Nutcracker Phenomenon and Nutcracker Syndrome

“…97,98 Later studies reported that it was close to 90° in healthy individuals, with angles smaller than half that in patients with NCP. 21,23,24 Other studies suggested half smaller numbers for normal and NCP variants, consistent with earlier reports. 65,99 Despite this reported variability, smaller AMAs have been associated with NCP compared with healthy controls; however, when the third portion of the duodenum courses between the aorta and the SMA (duodenal interposition), the LRV compression occurs even with a larger AMA.…”

“…18,23,100,105,106 Renal angiography shows delayed venous washout from the left kidney. Intravenous urograms and retrograde pyelograms often reveal normal findings, even in the presence of unilateral hematuria on cystoscopy 21,24,107 ; however, notching from varicosities of the renal pelvis and ureters may be seen. 47,56,108 Attempts to validate LRV diameter ratios have been unsuccessful given that LRV dilatation may be a normal variant.…”

“…[17][18][19][20] Theories of causes of NCP include posterior renal ptosis, an abnormally high course of the LRV, and an abnormal SMA branching from the aorta. [21][22][23][24] Compression of the LRV may also be produced by pancreatic neoplasms, para-aortic lymphadenopathy, retroperitoneal tumors, overarching testicular artery, or strangulating fibrolymphatic tissue between the SMA and the aorta.…”

Late renal vein aneurysm following living related renal transplant

“…The latter has been described as in the "nutcracker syndrome," where compression of the left renal vein between the superior mesenteric artery and the anterior aorta can lead to venous hypertension and gonadal varices. 7 Most renal vein aneurysms involve the left renal vein, which undergoes more complicated embryological development because of its increased length. 5 The donor in this case underwent a left nephrectomy, although no signs of the nutcracker syndrome were present on preoperative imaging.…”

Blood pool contrast agents for venous magnetic resonance imaging

“…The most accepted hypotheses proposed to explain the compression are posterior renal ptosis, abnormal high course of the LRV or an abnormal origin of the SMA from the aorta (30,33).…”