Unenhanced and dynamic contrast enhanced (DCE) MRI in assessment of scaphoid fracture non-union revisited: role in pre-operative planning

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1 Unenhanced and dynamic contrast enhanced (DCE) MRI in assessment of scaphoid fracture non-union revisited: role in pre-operative planning Poster No.: B-0440 Congress: ECR 2014 Type: Authors: Keywords: DOI: Scientific Paper S. Janardhan, S. Withey, S. Tan, S. Choudhary; Birmingham/UK Extremities, Musculoskeletal bone, Contrast agents, MR, Contrast agent-intravenous, Imaging sequences, Computer Applications- Detection, diagnosis, Trauma, Outcomes, Ischemia / Infarction /ecr2014/B-0440 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 15

2 Purpose Scaphoid nonunion has been implicated to impaired proximal pole blood supply secondary to traumatic vascular disruption[1]. Accurate pre-operative assessment of proximal pole vascularity aids in appropriate surgical planning for treatment of scaphoid fracture non union. Various studies over recent years have used unenhanced and contrast enhanced MRI (both delayed and dynamic acquisition) for preoperative evaluation of vascular status of the proximal scaphoid pole with variable results[2-6]. Our study aims to evaluate the technique and usefulness of DCE-MRI in pre-operative assessment and surgical planning in treatment of scaphoid non-union at our institution. Methods and materials A retrospective study conducted between January 2008 and May 2013 identified 20 patients who underwent pre-operative dynamic Gadolinium-enhanced wrist MRI on 3T. The time interval between the initial injury and MRI study date was recorded. The time between MRI scan and surgery was also noted. Majority of the scans were performed on a 3T scanner (Siemens 3T Verio) with the exception of a few claustrophobic patients performed on 1.5T. Standard unenhanced MR sequences were acquired followed by dynamic contrast enhanced sequences. 0.1 mmol/ kg Gadolinium was injected at 3 ml/s and coronal T1 weighted high resolution scans with fat saturation were performed. MRI scans were reviewed independently by 2 musculoskeletal radiologists blinded to the intraoperative findings. Unenhanced T1 signal of the proximal scaphoid pole and subjective assessment of its enhancement pattern in relation to the distal pole as well as the adjacent normal bone were analysed. On dynamic enhanced sequences, the regions of interest were defined in the proximal, distal scaphoid poles and radial styloid [Fig 1] and using Siemens Mean curve software, a contrast enhancement curve was generated. The steepest upslope of gadolinium enhancement curve was assessed to determine the degree of vascularity. Results were graded as normal [Fig 2-4], impaired vascularity and avascular necrosis [Fig 5-7]. Intra-operative findings were used as gold standard. Images for this section: Page 2 of 15

3 Fig. 1: Post gadolinium coronal fat saturated T1 image with regions of interest defined in the proximal, distal scaphoid poles and radial styloid process. Page 3 of 15

4 Fig. 2: Unenhanced T1 weighted coronal image shows normal bone marrow signal in proximal scaphoid pole; the present series suggests this does not necessarily indicate proximal pole viability. Page 4 of 15

5 Fig. 3: Enhanced T1 weighted image shows an enhancing proximal scaphoid pole in relation to the adjacent bones suggesting viability. Page 5 of 15

6 Fig. 4: Contrast enhancement curve generated on a viable scaphoid with regions of interest defined in the proximal, distal scaphoid poles and radial styloid. The curve close to the baseline corresponds to enhancement in radial styloid(rs), the dotted line corresponds to proximal pole (PP) and the dashed line corresponds to the distal pole (DP). The steepest upslope of gadolinium enhancement curve in the proximal pole and the distal pole suggest adequate vascularity Page 6 of 15

7 Fig. 5: T1 weighted coronal image demonstrates low marrow signal in the proximal pole consistent with marrow oedema Page 7 of 15

8 Fig. 6: Following IV Gadolinium administration, there is uptake along the fracture line in the scaphoid waist but no enhancement in the proximal pole indicating avascularity. Appropriate placement of the ROI in quantitative analysis of proximal pole vascularity is therefore important to avoid granulation tissue close to the fracture plane, which is a potential source of a false positive result. Page 8 of 15

9 Fig. 7: The contrast enhancement curves from the proximal scaphoid (dashed line) and distal scaphoid poles (continuous line) are flatter indicating poor vascularity in proximal scaphoid Page 9 of 15

10 Results 14/20(70%) scans corresponded to intra-operative findings of the proximal pole vascularity. 5/20(25%) had discordant results of which 4/5 cases had time interval of more than 7 months between injury and scans. 1/20 had no intra-operative confirmation. Sensitivity, specificity and accuracy of the DCE-MRI were 64%, 100% and 74% respectively. In 7/20 confirmed AVN cases, fat signal was demonstrable on unenhanced T1 images making it a non-specific finding [Fig 11-12]. Images for this section: Fig. 8: 14/20 cases had concordant MRI and intraoperative findings. 1/20 had no intraoperative confirmation Page 10 of 15

11 Fig. 9: Time between initial injury and MRI scan. All cases with the time interval longer than 7 months between the initial injury and MRI scan had discordant results. Fig. 10: Time between MRI scan and surgery Page 11 of 15

12 Fig. 11: In this case, unenhanced T1 weighted images demonstrated fat signal in the proximal pole however the contrast enhancement curve [Fig 12] demonstrated poor gadolinium uptake indicating avascularity. Intra-operative findings confirmed avascular necrosis. This is an example case which suggests that fat signal on T1 weighted images is a non specific finding. Page 12 of 15

13 Fig. 12: In this case, unenhanced T1 weighted images [Fig 11] demonstrated fat signal in the proximal pole however the contrast enhancement curve demonstrated poor gadolinium uptake indicating avascularity. Intra-operative findings confirmed avascular necrosis. This is an example case which suggests that fat signal on T1 weighted images is a non specific finding. Page 13 of 15

14 Conclusion Dynamic contrast enhanced MRI is a reliable tool for pre-operative assessment of proximal pole vascularity and surgical planning. However MRI results may be confounded if the fracture is old (>7 months). Personal information References 1. Barton NJ. Twenty questions about scaphoid fractures. J Hand Surg [Br] 1992;17: Cerezal L, Abascal F, Canga A, García-Valtuille R, Bustamante M, del Piñal F. Usefulness of gadolinium-enhanced MR imaging in the evaluation of the vascularity of scaphoid nonunions. AJR Am J Roentgenol Jan;174(1): Dawson JS, Martel AL, Davis TR. Scaphoid blood flow and acute fracture healing. A dynamic MRI study with enhancement with gadolinium. J Bone Joint Surg Br Aug;83(6): Fox MG, Gaskin CM, Chhabra AB, Anderson MW. Assessment of scaphoid viability with MRI: a reassessment of findings on unenhanced MR images. AJR Am J Roentgenol Oct;195(4):W doi: /AJR Schmitt R, Christopoulos G, Wagner M, Krimmer H, Fodor S, van Schoonhoven J, Prommersberger KJ. Avascular necrosis (AVN) of the proximal fragment in scaphoid nonunion: is intravenous contrast agent necessary in MRI? Eur J Radiol Feb;77(2): doi: /j.ejrad Epub 2010 Oct Donati OF, Zanetti M, Nagy L, Bode B, Schweizer A, Pfirrmann CW. Is dynamic gadolinium enhancement needed in MR imaging for the preoperative assessment of scaphoidal viability in patients with scaphoid nonunion? Radiology Sep;260(3): doi: /radiol Epub 2011 Jun 28. Page 14 of 15

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