Ex vivo tissue imaging for radiology–pathology correlation: a pilot study with a small bore 7-T MRI in a rare pigmented ganglioglioma exhibiting complex MR signal characteristics associated with melanin and hemosiderin

Abstract

, "Ex vivo tissue imaging for radiology-pathology correlation: a pilot study with a small bore 7-T MRI in a rare pigmented ganglioglioma exhibiting complex MR signal characteristics associated with melanin and hemosiderin," J. Med. Imag. 4(3), 036001 (2017), doi: 10.1117/1.JMI.4.3.036001. Abstract. To advance magnetic resonance imaging (MRI) technologies further for in vivo tissue characterization with histopathologic validation, we investigated the feasibility of ex vivo tissue imaging of a surgically removed human brain tumor as a comprehensive approach for radiology-pathology correlation in histoanatomically identical fashion in a rare case of pigmented ganglioglioma with complex paramagnetic properties. Pieces of surgically removed ganglioglioma, containing melanin and hemosiderin pigments, were imaged with a small bore 7-T MRI scanner to obtain T1-, T2-, and T2*-weighted image and diffusion tensor imaging (DTI). Corresponding histopathological slides were prepared for routine hematoxylin and eosin stain and special stains for melanin and iron/hemosiderin to correlate with MRI signal characteristics. Furthermore, mean diffusivity (MD) maps were generated from DTI data and correlated with cellularity using image analysis. While the presence of melanin was difficult to interpret in in vivo MRI with certainty due to concomitant hemosiderin pigments and calcium depositions, ex vivo tissue imaging clearly demonstrated pieces of tissue exhibiting the characteristic MR signal pattern for melanin with pathologic confirmation in a histoanatomically identical location. There was also concordant correlation between MD and cellularity. Although it is still in an initial phase of development, ex vivo tissue imaging is a promising approach, which offers radiology-pathology correlation in a straightforward and comprehensive manner.

MR susceptibility imaging for detection of tumor-associated macrophages in glioblastoma

“…In this study, we also performed an ex vivo MR imaging on para n-embedded blocks from three subjects with minimal hemorrhage to allow comprehensive radiology-pathology correlation (32). Using a similar T2* relaxometry technique, several studies in preclinical tumor models demonstrated successful mapping of TAMs in treatment naïve tumors and in the context of immunotherapy (19,20,32,33). We also observed that R2* values correlated with both CD68 and CD86 positive cell counts in multiple ROIs randomly placed on areas of highly dense tumor and co-registered with MRI.…”

Ultrasound and magnetic resonance imaging for the detection of blood: An ex‐vivo study

“…These observations could partly be attributed to the influence of temperature and relaxation rates on MRI imaging properties 21,22 . Other studies have also reported that MRI scanners and parameters used for in vivo imaging cannot be identically replicated while performing MRI in ex‐vivo studies 23–27 . Better MRI phantom models/in vivo studies using patients are warranted for the detection of the sensitivity of MRI in the detection of blood in body fluids.…”

“…Other studies have also reported that MRI scanners and parameters used for in vivo imaging cannot be identically replicated while performing MRI in ex-vivo studies. [23][24][25][26][27] Better MRI phantom models/ in vivo studies using patients are warranted for the detection of the sensitivity of MRI in the detection of blood in body fluids. One of the limitations of the USG component of the study is that images were not scored multiple times by each radiologist, and hence, intraobserver variability could not be assessed.…”

Tensor image registration library: Deformable registration of stand‐alone histology images to whole‐brain post‐mortem MRI data

“…Depending on the aim, MRI-microscopy datasets can vary along many axes: (1) whole brain ( Amunts et al., 2013 ) vs tissue blocks ( Gangolli et al., 2017 ), (2) serial histological sectioning ( Tullo et al., 2018 ) vs single-section sampling ( Meyer et al., 2006 ), (3) large ( Bagnato et al., 2018 ) vs small ( Meadowcroft et al., 2015 ) histology sections, (4) excised/biopsied tissue imaging ( Matsuda et al., 2017 ) vs post-mortem MRI ( Jonkman et al., 2019 ), and (5) the exact combination of MRI and microscopy modalities used. This diversity of the input data presents unique challenges ( Alyami et al., 2022 ) for the alignment of MRI-microscopy images (e.g., extreme contrast differences, vastly different spatial resolutions, 2D vs 3D image domains), which are difficult to overcome with existing registration software that was not optimised for this task.…”