Can Ex Vivo Magnetic Resonance Imaging of Rectal Cancer Specimens Improve the Mesorectal Lymph Node Yield for Pathological Examination?
Stijns, Rutger MD*,†; Philips, Bart MD*; Wauters, Carla MD, PhD‡; de Wilt, Johannes MD, PhD†; Nagtegaal, Iris MD, PhD§; Scheenen, Tom PhD*
Investigative Radiology: June 18, 2019 - Volume Publish Ahead of Print - Issue - p
doi: 10.1097/RLI.0000000000000581
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Purpose The aim of this study was to use 7 T ex vivo magnetic resonance imaging (MRI) scans to determine the size of lymph nodes (LNs) in total mesorectal excision (TME) specimens and to increase the pathological yield of LNs with MR-guided pathology.
Materials and Methods Twenty-two fixated TME specimens containing adenocarcinoma were scanned on a 7 T preclinical MRI system with a T1-weighted 3-dimensional gradient echo sequence with frequency-selective lipid excitation (repetition time/echo time, 15/3 milliseconds; resolution, 0.293 mm3) and a water-excited 3-dimensional multigradient echo (repetition time, 30 milliseconds; computed echo time, 6.2 milliseconds; resolution, 0.293 mm3) pulse sequence.
The first series of 11 TME specimens (S1) revealed the number and size of LNs on both ex vivo MRI and histopathology. The second series of 11 TME specimens (S2) was used to perform MR-guided pathology. The number, size, and percentages of yielded LNs of S1 and S2 were compared.
Results In all specimens (22/22), a median number of 34 LNs (interquartile range, 26–34) was revealed on ex vivo MRI compared with 14 LNs (interquartile range, 7.5–21.5) on histopathology (P = 0.003). Mean size of all LNs did not differ between the 2 series (ex vivo MRI: 2.4 vs 2.5 mm, P = 0.267; pathology: 3.6 vs 3.5 mm, P = 0.653). The median percentages of harvested LNs compared with nodes visible on ex vivo MRI per specimen for both series were not significantly different (40% vs 43%, P = 0.718). By using a size threshold of greater than 2 mm, the percentage improved to 71% (S1) and to 78% (S2, P = 0.895). The median number of harvested LNs per specimen did not increase by performing MR-guided pathology (S1, 14 LNs; S2, 20 LNs; P = 0.532).
Conclusions Ex vivo MRI visualizes more LNs than (MR-guided) pathology is able to harvest. Current pathological examination was not further improved by MR guidance. The majority of LNs or LN-like structures visible on ex vivo MRI below 2 mm in size remain unexplained, which warrants a 3-dimensional approach for pathological reconstruction of specimens.
This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.
Stijns, Rutger MD*,†; Philips, Bart MD*; Wauters, Carla MD, PhD‡; de Wilt, Johannes MD, PhD†; Nagtegaal, Iris MD, PhD§; Scheenen, Tom PhD*
Investigative Radiology: June 18, 2019 - Volume Publish Ahead of Print - Issue - p
doi: 10.1097/RLI.0000000000000581
Original Article: PDF Only
OPEN
SDC
PAP
Abstract
Author Information
Article Metrics
Purpose The aim of this study was to use 7 T ex vivo magnetic resonance imaging (MRI) scans to determine the size of lymph nodes (LNs) in total mesorectal excision (TME) specimens and to increase the pathological yield of LNs with MR-guided pathology.
Materials and Methods Twenty-two fixated TME specimens containing adenocarcinoma were scanned on a 7 T preclinical MRI system with a T1-weighted 3-dimensional gradient echo sequence with frequency-selective lipid excitation (repetition time/echo time, 15/3 milliseconds; resolution, 0.293 mm3) and a water-excited 3-dimensional multigradient echo (repetition time, 30 milliseconds; computed echo time, 6.2 milliseconds; resolution, 0.293 mm3) pulse sequence.
The first series of 11 TME specimens (S1) revealed the number and size of LNs on both ex vivo MRI and histopathology. The second series of 11 TME specimens (S2) was used to perform MR-guided pathology. The number, size, and percentages of yielded LNs of S1 and S2 were compared.
Results In all specimens (22/22), a median number of 34 LNs (interquartile range, 26–34) was revealed on ex vivo MRI compared with 14 LNs (interquartile range, 7.5–21.5) on histopathology (P = 0.003). Mean size of all LNs did not differ between the 2 series (ex vivo MRI: 2.4 vs 2.5 mm, P = 0.267; pathology: 3.6 vs 3.5 mm, P = 0.653). The median percentages of harvested LNs compared with nodes visible on ex vivo MRI per specimen for both series were not significantly different (40% vs 43%, P = 0.718). By using a size threshold of greater than 2 mm, the percentage improved to 71% (S1) and to 78% (S2, P = 0.895). The median number of harvested LNs per specimen did not increase by performing MR-guided pathology (S1, 14 LNs; S2, 20 LNs; P = 0.532).
Conclusions Ex vivo MRI visualizes more LNs than (MR-guided) pathology is able to harvest. Current pathological examination was not further improved by MR guidance. The majority of LNs or LN-like structures visible on ex vivo MRI below 2 mm in size remain unexplained, which warrants a 3-dimensional approach for pathological reconstruction of specimens.
This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.
Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.
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