Preoperative assessment of ureter using double-phase contrast enhanced CT. Shunsuke Fujibayashi

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1 EUROSPINE 2015 SEPT.2-4, COPENHAGEN, DENMARK Preoperative assessment of ureter using double-phase contrast enhanced CT Shunsuke Fujibayashi Bungo Otsuki, Hiroaki Kimura, Shuichi Matsuda Department of Orthopaedic Surgery Graduate School of Medicine Kyoto University, Kyoto, JAPAN

2 Introduction p Minimally invasive lateral lumbar interbody fusion (LLIF), such as XLIF (extreme lateral interbody fusion) and OLIF (oblique lateral interbody fusion), are increasing in popularity among spine surgeons. p Although these surgical corridors are a little different, both are close to retroperitoneal important structures. Recently, direct injury to the ureter and kidney has been described as access related surgical complications of XLIF. These injuries are one of the devastating complications that should be concerned during LLIF. p In the current study, we introduce dual-phase CT and assess the location of ureteral and vascular structures simultaneously, and discuss the risk of these injuries during both procedures.

3 Materials and methods p 12 consecutive OLIF cases were enrolled in this study. p Preoperatively, intravenous contrast material was administered with a split-bolus technique before CT scanning to enhance ureters and abdominal vessels simultaneously. p The location of ureter was evaluated bilaterally at L2/3, 3/4, 4/5 levels using axial and 3D images. p The location of ureter was divided into six parts as reference to vertebral body (VB) and psoas muscle (PM). p A total of 72 ureters were evaluated and compared with intraoperative findings.

4 Double-phase contrast enhanced CT 1. All images were performed with 64-MDCT scanners. 2. The acquisition parameters were as follows: tube voltage, 100kV: gantry rotation, 0.75sec/ rotation: table feed, 26.5mm/rotation. 3. IV contrast material (Omnipaque 300) was administered with a split-bolus technique as follows: 30 ml (350~370mgI/ml) was administered at a rate of 2 ml/s for the enhancement of ureter. 4. After a 5-minute delay, an additional 70 ml was administered at 2mL/s for the enhancement of abdominal vessels. 5. The data acquisition was triggered using the bolus tracking method, with the region of interest placed in the inferior vena cava and the trigger threshold level set to the CT value of 150 HU.

5 Materials and methods Clssification1 referenced to VB Clssification2 referenced to PM I-v II-v III-v I-p II-p III-p I-p II-p III-p Imagination of XLIF procedure Imagination of OLIF procedure

6 Results p 54 ureters were successfully evaluated radiologically, excluding 5 unclearly enhanced and 13 located in kidney. p In reference to VB, 59.2% was located at anterior to VB and remaining 40.7% was located at lateral to VB. p In reference to PM, 92.5% was located at anterior to PM. p At L2/3 level, 54.1% of kidneys were located at lateral to VB. p Intraoperative findings indicated that all ureters were successfully retracted anteriorly with peritoneal contents.

7 Results Classification1 Classification2 III-v 4% II-p 4% III-p 4% II-v 37% I-v 59% I-p 92%

8 Case presentation 76 yo F. LBP and rt. thigh pain OLIF(L3/4)

9 Case presentation Classification1 Classification2 I-v II-v III-v I-p II-p III-p I-p II-p III-p R R right: II-v left: I-v right: I-p left: I-p

10 Discussion Ureteral injury in spine surgery p ALIF: Isiklar ZU. SPINE 1996 p Posterior herniotomy: Cho KT. Surg Neurology 2008 p Laparoscopic surgery: Guingrich JA. SPINE 2000 p Anterior T-L: Bjurlin MA. The Spine J 2009 Symptom abdominal pain, nausea & vomiting, fever, ileus, peritonitis, sepsis Treatment options percutaneous drainage, retrograde stenting ü Urological injury as a complication of the transpsoas approach for disectomy and interbody fusion. Anand N. J Neurosurg Spine 2013

11 Discussion & Conclusion Peritoneal Cavity Peritoneal Cavity XLIF Psoas Kidney Psoas Kidney ü XLIF corridor is created at midportion of VB, whereas OLIF corridor is created at anterior border of PM. ü During the procedure of XLIF, ureter may be close to the surgical corridor ( 40%). ü During the procedure of OLIF, ureter is likely to be closest to the surgical corridor (> 90%). ü Surgeons should keep in mind that complete retraction of peritoneal content during both procedures is mandatory and will avoid ureteral injury. ü Preoperative dual-phase enhanced CT will provide important information about retroperitoneal structures for LLIF.

12 Disclosure No funds were received in support of this study. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this paper.! This study was approved by Institutional Ethics Committee in Kyoto University.