Reliable registration of preoperative MRI with histopathology after temporal lobe resections.
OBJECTIVE
Conventional and novel magnetic resonance imaging (MRI) techniques can detect cerebral abnormalities in patients with refractory focal epilepsies. Correlation of preoperative MRI and histopathology is important to validate MRI findings, but in practice is far from straightforward. Peroperative neuronavigation and placement of markers on tissue is of limited use in temporal lobe resections. MRI scanning of the resected specimen for registration with in vivo MRI is complicated by anisotropic tissue deformation. We have developed a method to facilitate registration of preoperative MRI with the resected specimen and to enable correlation of MRI findings with histopathology.


METHODS
Sixteen en bloc temporal lobe resections undertaken for refractory temporal lobe epilepsy were studied. The specimens were fixed in formalin and then cut coronally by using a cradle with parallel blades at 5-mm intervals to ensure evenly thick tissue slices in the same orientation. Volumetric T1-weighted preoperative MRIs were reformatted, and consecutive slices (0.94 mm) cut in the same orientation as the resected lobe were visually compared with photographs of tissue slices by two independent observers.


RESULTS
In 15 (94%) of 16 cases, a <2-mm difference was found between the two observers' matches of MRI slices with tissue slices. In the last case, a 4-mm difference was noted. In all cases, a consensus was reached by the two observers. The suggested MRI-histology matches were within the resections seen on postoperative scans.


CONCLUSIONS
Careful labelling and postoperative handling and slicing ensured histopathologic tissue slices of uniform thickness and slicing angle. This technique can be applied to a range of MRI datasets, enabling exploration of the pathologic basis of abnormalities on conventional and novel MRI acquisitions.
Eriksson
Sofia H
SH
Department of Clinical and Experimental Epilepsy, National Society for Epilepsy, United Kingdom. s.eriksson@ion.ucl.ac.uk
Free
Samantha L
SL
Thom
Maria
M
Harkness
William
W
Sisodiya
Sanjay M
SM
Duncan
John S
JS
D038481:Anterior Temporal Lobectomy / Q000379:methods; D001931:Brain Mapping / Q000379:methods; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000601:surgery*; D005260:Female; D016591:Histocytological Preparation Techniques / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008499:Medical Records / Q000706:statistics & numerical data*; D038361:Neuronavigation / Q000379:methods / Q000706:statistics & numerical data; D011182:Postoperative Care / Q000379:methods; D011300:Preoperative Care; D015203:Reproducibility of Results; D013048:Specimen Handling / Q000379:methods; D013702:Temporal Lobe / Q000002:abnormalities / Q000473:pathology* / Q000601:surgery