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Ex vivo MRI evaluation of vulvar cancer to predict resection margins in fresh wide local excision specimens: a pilot study
Jan Heidkamp1, Petra Zusterzeel2, Andor Veltien1, Arie Maat3, Ilse Van Engen-Van Grunsven3, and Jurgen Fütterer1

1Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, Netherlands, 2Obstetrics and Gynaecology, Radboud university medical center, Nijmegen, Netherlands, 3Pathology, Radboud university medical center, Nijmegen, Netherlands

Synopsis

Currently there’s no accurate and topical peroperative information available on the margin status of wide local resection specimens containing vulvar cancer. In this pilot study we performed a qualitative image evaluation of ex vivo 7T MR images acquired of fresh specimens of the vulva containing vulvar cancer using different MRI sequences. High resolution T2 weighted images obtained the highest score for image quality, visibility of the tumor, and visibility of the transition between the epidermis and the resection surface.

Introduction

Vulvar cancer is a relatively uncommon disease accounting for approximately 5% of all gynaecological malignancies1,2. Currently, wide local excision (WLE) is the preferred treatment of the primary tumor in early stage disease3–7. The success of this approach depends on the achievement of tumor free margins which are considered the most important predictive factor for local recurrences8–11. The challenge in treatment of vulvar cancer is to keep surgical margins large enough to minimize the chance of local recurrence, but at the same time, preserve as much genital tissue as possible to diminish morbidity to urethra, clitoral tissue or anal sphincter. The surgeon is hampered by the fact that no accurate and topical information on the margin status is available during or direct after the surgery. The goal of this pilot study was to investigate whether ex vivo 7T MRI is a feasible technique to visualize vulvar cancer and the transition between epidermis and resection surface in fresh WLE specimens.

Methods

Approval of our Institutional Review Board and written informed consent from all patients (n=11) were obtained. Consecutive patients who had biopsy proven vulvar cancer and who were scheduled for WLE were prospectively included. Directly after surgery the entire, intact, vulva specimen was positioned in a specifically designed container and was scanned using a 7 Tesla preclinical MR scanner interfaced to a Siemens console. Axial T1 weighted (T1W, FLASH, TE/TR = 3/400, voxel size = 0.31x0.31x1 mm), T2 weighted (T2W, TSE, TE/TR = 13, 26, 53/6,090-12,470, voxel size = 0.31x0.31x1 mm), and diffusion weighted (DW, HASTE, TE/TR = 53/2,130, voxel size = 0.63x0.63x1 mm, b-values = 0, 100, 500, 1000, 1200 s/mm2) images were acquired. Furthermore, one T2W image set (TSE, TE/TR = 14/6,400-13,120, voxel size = 0.16x0.16x1 mm) was acquired in extra high resolution. Apparent diffusion coefficient (ADC) maps were calculated. A radiologist performed qualitative evaluation of the general image quality of each of the vulva specimens. The datasets were assessed using the following 5-point rating scale12: 1, very poor or non-diagnostic quality images; 2, low image quality that degraded confidence in diagnosis; 3, moderate image quality sufficient for diagnosis; 4, good image quality; 5, excellent image quality enabling visualisation of even small structures. Next to general image quality, the visibility‎ of the tumor and the transition between epidermis and resection surface were qualitatively assessed by applying the following scale: 1, very poor; 2, low; 3, sufficient; 4, good; 5, excellent. The median, interquartile range and extreme values of the results were calculated and represented in box plots.

Results

Ex vivo MRI of WLE specimen produced good quality images at which vulvar cancer was well visible. The transition between epidermis and resection surface was sufficiently to very poorly visible. In general, the T2W sequences, particularly the T2W-14 HighRes sequence, demonstrated the highest median scores for image quality (median=5), visibility of the tumor (median=5), and visibility of the epidermis-resection edge transition (median=4). The scores were not dependent on the used echo time, except for the visibility of the epidermis-resection edge transition that was assigned a lower median score at the T2W-53. The b1000 DW sequence and the ADC-map demonstrated good results for tumor visualisation (medians= 4; 4), yet visualisation of the epidermis-resection surface transition was very bad (medians=1; 1). Although the T1W sequence provided good image quality (median=4), it did not perform well in visualization of the tumor and epidermis-resection edge transition (medians=3; 1.5).

Discussion

It is feasible to perform ex vivo MR images from WLE specimens containing vulvar cancer. Similar to low field strength MRI, vulvar cancer has low signal intensity on T1W images and moderate-to-high signal intensify on T2W images13. Furthermore, vulvar cancer demonstrates diffusion restriction probably as a result a higher cellular density. Limitations are the small number of patients and the fact that this was a one reader study. This precursory study investigated whether ex vivo MRI of WLE specimens was feasible at all and what MR sequence results in the best image quality, tumor visibility and visibility of the transition between epidermis and resection surface. The results of this study will be employed in a succeeding study that will investigate whether ex vivo MRI can be applied to localize vulva cancer and subsequently predict resection margins in fresh WLE specimens.

Conclusion

Ex vivo MRI of fresh WLE specimens containing vulvar cancer is a feasible. High resolution T2W images provided the highest image quality and have proved to be the best sequence to visualize vulvar cancer and the transition between epidermis and resection surface.

Acknowledgements

Ex vivo MRI was performed using equipment of the Preclinical Imaging Centre (PRIME) within the Radboud university medical center, Nijmegen, the Netherlands.

References

1. Siegel RL, Miller KD, Jemal A. Cancer statistics , 2015 . CA Cancer J Clin. 2015;65(1):5–29.

2. Lai J, Elleray R, Nordin A, et al. Vulval cancer incidence, mortality and survival in England: age-related trends. BJOG An Int J Obstet Gynaecol. 2014;121(6):728–738.

3. Ansink A, van der Velden J. Surgical interventions for early squamous cell carcinoma of the vulva. Cochrane Database Syst Rev. 2000;(2):CD002036.

4. de Hullu JA, van der Zee AGJ. Surgery and radiotherapy in vulvar cancer. Crit Rev Oncol Hematol. 2006;60(1):38–58.

5. Stehman FB, Look KY. Carcinoma of the vulva. Obstet Gynecol. 2006;107(3):719–733.

6. Micheletti L, Preti M. Surgery of the vulva in vulvar cancer. Best Pract Res Clin Obstet Gynaecol. 2014;28(7):1074–1087.

7. Alkatout I, Schubert M, Garbrecht N, et al. Vulvar cancer: epidemiology, clinical presentation, and management options. Int J Womens Health. 2015;7:305–313.

8. Heaps JM, Fu YS, Montz FJ, Hacker NF, Berek JS. Surgical-pathologic variables predictive of local recurrence in squamous cell carcinoma of the vulva. Gynecol Oncol. 1990;38(3):309–314.

9. de Hullu JA, Hollema H, Lolkema S, et al. Vulvar carcinoma: The price of less radical surgery. Cancer. 2002;95(11):2331–2338.

10. Chan JK, Sugiyama V, Pham H, et al. Margin distance and other clinico-pathologic prognostic factors in vulvar carcinoma: A multivariate analysis. Gynecol Oncol. 2007;104:636–641.

11. Rouzier R, Haddad B, Plantier F, Dubois P, Pelisse M, Paniel BJ. Local relapse in patients treated for squamous cell vulvar carcinoma: Incidence and prognostic value. Obstet Gynecol. 2002;100(6):1159–1167.

12. Schueller-Weidekamm C, Schaefer-Prokop CM, Weber M, Herold CJ, Prokop M. CT angiography of pulmonary arteries to detect pulmonary embolism: improvement of vascular enhancement with low kilovoltage settings. Radiology. 2006;241(3):899–907.

13. Sohaib S, Richards P, Ind T, et al. MR imaging of carcinoma of the vulva. 2002;(February):373–377.

Figures

Specimen after performing wide local excision of a vulvar carcinoma on a 93-year-old female. On the left, a slight oblique/top view showing the specimen pinned down on the paraffin layer using 5 wooden pins. Furthermore, the two opposing rows of rods can be appreciated. In the middle, top view of the pinned down specimen with corresponding schematic drawing with indications from the surgeon on the right. This setup was used to serve succeeding study purposes as well. Sutures demarcate the 12 o’clock side of the specimen and the position at which the specimen was transected for surgical resection purposes.

Boxplots with results from the subjective qualitative image evaluation.

Ex vivo MRI and histology from a 74-year-old female who underwent WLE. With: (a), T1W image showing no contrast between the tumor and the surrounding tissue; (b-d), T2W images with similar parameters, yet with different TEs of 13, 26 and 53 showing differences in contrast between tumor and healthy tissue. A small hyperintense band demarcating the tumor from the surrounding tissue is appreciated; (e) T2W image in high resolution showing more anatomical details; (f,g), DW b1000 and ADC map with areas of diffusion restriction indicating cancer; (h), histological slide with tumor demarcation.

Proc. Intl. Soc. Mag. Reson. Med. 25 (2017)
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