Histopathological Validation Research Articles

Evaluation of Minimum-to-Severe Global and Macrovesicular Steatosis in Human Liver Specimens: A Portable Ambient Light-Compatible Spectroscopic Probe.

Hepatic steatosis (HS), particularly macrovesicular steatosis (MaS), influences transplant outcomes. Accurate assessment of MaS is crucial for graft selection. While traditional assessment methods have limitations, non-invasive spectroscopic techniques like Raman and reflectance spectroscopy offer promise. This study aimed to evaluate the efficacy of a portable ambient light-compatible spectroscopic system in assessing global HS and MaS in human liver specimens. A two-stage approach was employed on thawed snap-frozen human liver specimens under ambient room light: biochemical validation involving a comparison of fat content from Raman and reflectance intensities with triglyceride (TG) quantifications and histopathological validation, contrasting Raman-derived fat content with evaluations by an expert pathologist and a "Positive Pixel Count" algorithm. Raman and reflectance intensities were combined to discern significant (≥ 10%) discrepancies in global HS and MaS. The initial set of 16 specimens showed a positive correlation between Raman and reflectance-derived fat content and TG quantifications. The Raman system effectively differentiated minimum-to-severe global and macrovesicular steatosis in the subsequent 66 specimens. A dual-variable prediction algorithm was developed, effectively classifying significant discrepancies (> 10%) between algorithm-estimated global HS and pathologist-estimated MaS. Our study established the viability and reliability of a portable spectroscopic system for non-invasive HS and MaS assessment in human liver specimens. The compatibility with ambient light conditions and the ability to address limitations of previous methods marks a significant advancement in this field. By offering promising differentiation between global HS and MaS, our system introduces an innovative approach to real-time and quantitative donor HS assessments. The proposed method holds the promise of refining donor liver assessment during liver recovery and ultimately enhancingtransplantation outcomes.

Evaluation High-Resolution Computed Tomography (HRCT) Of Temporal Bone In Cholesteatoma Of Middle Ear In Comparison With Histopathological Findings: A Prospective Study

Background: Cholesteatoma is relatively common and potentially dangerous disease of the ear. It is characterised by local destruction and osseous erosion leading to complications. Pre-operative assessment of middle ear cholesteatoma is a must for assessing the disease's location, extent, and complication. High resolution computed tomography (HRCT) is the imaging modality of choice for evaluation of middle ear structures and pathology. Therefore, in the present study we aimed to evaluate HRCT of temporal bone in cholesteatoma of middle ear cleft in comparison with histopathological results. Materials and Methods: This is a prospective study carried out on total of 30 patients who were undergoing HRCT of temporal bone for middle ear cleft pathology and found to have imaging evidence of chronic otomastoiditis on HRCT, subsequently undergoing surgery and histopathological validation. Results: The mean age of study subjects was found to be 23.97 ± 11.30 years. Majority of the study subjects were belonged to age group of 11-40 years (40%) with female predominance (53.3%) as compared to male (46.7%). Majority of the patients i.e., 60% showed signs of loss of aeration and sclerosis of mastoid air cells followed by soft tissue density lesions (43.3%), bony erosions (26.7%), and bony expansions (6.7%). Surgical findings and histopathological reports were correlated with pre-operative HRCT scans analyses with 95.88% accuracy. Conclusion: Compared to histopathological findings, HRCT offers a diagnostic capacity that is remarkably sensitive and specific in identifying cholesteatoma and the condition of the bone structures in the temporal bone

Atypical connectome topography and signal flow in temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most common pharmaco-resistant epilepsy in adults. While primarily associated with mesiotemporal pathology, recent evidence suggests that brain alterations in TLE extend beyond the paralimbic epicenter and impact macroscale function and cognitive functions, particularly memory. Using connectome-wide manifold learning and generative models of effective connectivity, we examined functional topography and directional signal flow patterns between large-scale neural circuits in TLE at rest. Studying a multisite cohort of 95 patients with TLE and 95 healthy controls, we observed atypical functional topographies in the former group, characterized by reduced differentiation between sensory and transmodal association cortices, with most marked effects in bilateral temporo-limbic and ventromedial prefrontal cortices. These findings were consistent across all study sites, present in left and right lateralized patients, and validated in a subgroup of patients with histopathological validation of mesiotemporal sclerosis and post-surgical seizure freedom. Moreover, they were replicated in an independent cohort of 30 TLE patients and 40 healthy controls. Further analyses demonstrated that reduced differentiation related to decreased functional signal flow into and out of temporolimbic cortical systems and other brain networks. Parallel analyses of structural and diffusion-weighted MRI data revealed that topographic alterations were independent of TLE-related cortical thinning but partially mediated by white matter microstructural changes that radiated away from paralimbic circuits. Finally, we found a strong association between the degree of functional alterations and behavioral markers of memory dysfunction. Our work illustrates the complex landscape of macroscale functional imbalances in TLE, which can serve as intermediate markers bridging microstructural changes and cognitive impairment.

Characterization of renal fibrosis in rats with chronic kidney disease by in vivo tomoelastography.

Chronic kidney disease (CKD) is characterized by structural changes, such as tubular atrophy, renal fibrosis, and glomerulosclerosis, all of which affect the viscoelastic properties of biological tissues. However, detection of renal viscoelasticity changes because diagnostic markers by in vivo elastography lack histopathological validation through animal models. Therefore, we investigated in vivo multiparametric magnetic resonance imaging (mp-MRI), including multifrequency magnetic resonance elastography-based tomoelastography, in the kidneys of 10 rats with adenine-induced CKD and eight healthy controls. Kidney volume (in mm3 ), water diffusivity (apparent diffusion coefficient [ADC] in mm2 /s), shear wave speed (SWS; in m/s; related to stiffness), and wave penetration rate (PR; in m/s; related to inverse viscosity) were quantified by mp-MRI and correlated with histopathologically determined renal fibrosis (collagen area fraction [CAF]; in %). Kidney volume (40% ± 29%, p = 0.009), SWS (11% ± 12%, p = 0.016), and PR (20% ± 15%, p = 0.004) were significantly increased in CKD, which was accompanied by ADC (-24% ± 27%, p = 0.02). SWS, PR, and ADC were correlated with CAF with R = 0.63, 0.75, and -0.5 (all p < 0.05), respectively. In the CKD rats, histopathology showed tubule dilation due to adenine crystal deposition. Collectively, our results suggest that collagen accumulation during CKD progression transforms soft-compliant renal tissue into a more rigid-solid state with reduced water mobility. We hypothesized that tubule dilation-a specific feature of our model-might lead to higher intraluminal pressure, which could also contribute to elevated renal stiffness. Tomoelastography is a promising tool for noninvasively assessing disease progression, detecting biomechanical properties that are sensitive to different pathologic features of CKD.

Diffusion-time dependent diffusion MRI: effect of diffusion-time on microstructural mapping and prediction of prognostic features in breast cancer.

This study aimed to evaluate the effect of achievable td on the accuracy of microstructural mapping based on simulation and patient experiments, and investigate the feasibility of td-dMRI in distinguishing prognostic factors in breast cancer patients. Simulation was performed using different td settings. Patients with breast cancer were enrolled prospectively between November 2020 and January 2021, who underwent oscillating and pulsed gradient encoded dMRI on a 3-T scanner using short-/long-td protocol with oscillating frequency up to 50/33Hz. Data were fitted with a two-compartment model to estimate cell diameter (d), intracellular fraction (fin), and diffusivities. Estimated microstructural markers were used to differentiate immunohistochemical receptor status and the presence of lymph node (LN), which were correlated with histopathological measurements. Simulation results showed that d fitted from the short-td protocol significantly reduced estimation error than those from long-td (2.07 ± 1.51% versus 3.05 ± 1.92%, p < 0.0001) while the estimation error of fin was robust to different protocols. Among a total of 37 breast cancer patients, the estimated d was significantly higher in HER2-positive and LN-positive (p < 0.05) groups compared to their negative counterparts only using the short-td protocol. Histopathological validation in a subset of 6 patients with whole slide images showed the estimated d was highly correlated with measurements from H&E staining (r = 0.84, p = 0.03) only using the short-td protocol. The results indicated the necessity of short-td for accurate microstructural mapping in breast cancer. The current td-dMRI with a total acquisition time of 4.5min showed its potential in the diagnosis of breast cancer. • Short td is important for accurate microstructural mapping in breast cancer using the td-dMRI technique, based on simulation and histological validation. • The 4.5-min td-dMRI protocol showed potential clinical value for breast cancer, given the difference in cell diameter between HER2/LN positive and negative groups.

The predictive value of tissue response viewer for lesion transmurality in a porcine model

BackgroundThe tissue response viewer (TRV) is a multiparametric index that incorporates time, power, tissue pressure, impedance, and wall thickness data during radiofrequency catheter ablation (RFCA) and is used to predict the transmurality of lesions. This study aimed to evaluate the feasibility and accuracy of the TRV in a porcine model. MethodsTwelve pigs underwent preablation high-density voltage and activation mapping of two atria, and both were repeated after linear RFCA. Intentional gaps were kept in the left atrium (LA) and were touched up in the right atrium (RA). Standard and high powers were, respectively, performed in the LA ablation. Six pigs were immediately sacrificed for pathological examination after the mapping and ablation procedure (acute study). Another six pigs were kept for 4 weeks before remapping and pathological examination (chronic study). ResultsAll animals completed the planned procedure. The TRV function showed a sensitivity of 97.1% and a specificity of 76.9% in the acute study, and a sensitivity of 95.9% and a specificity of 72.5% in the chronic study to predict the transmural lesion. All positive and negative predictive values were over 80%. In addition, the TRV achieved higher sensitivity (92.3% vs. 85.0%) and specificity (88.2% vs. 78.9%) to predict the transmural lesion in LA ablation with high power compared with standard ablation. ConclusionsThis study presents the histopathological validation of TRV to predict transmural lesions. The use of TRV may guide a more individual ablation and a more precise touch-up of gaps for atrial arrhythmias.

Inter‐Observer variability in MRI‐based target volume delineation of uveal melanoma

AbstractPurpose: Several efforts are being undertaken towards MRI‐based treatment planning for ocular proton therapy for uveal melanoma (UM). The inter‐observer variability of the gross target volume (GTV) on MRI is one of the important parameters to design safety margins for a reliable treatment. Therefore, this study assessed the inter‐observer variation in tumour delineation of UM on MRI.Methods: Six observers delineated the tumour in 10 different UM patients using the Big Brother contouring software. Patients were scanned at 3 T MRI with a surface coil and tumours were delineated separately on contrast enhanced 3DT1 (T1gd) and 3DT2‐weighted scans with a resolution of 0.8 mm isotropic for the acquisition voxels (1). Volume difference and overall local variation were analysed for each patient. Additionally the local variation was analysed for four interfaces: sclera, vitreous, retinal detachment, and tumour‐choroid interface.Results: The average tumour contour was significantly larger on T1gd (0.57 cm3) compared to T2 (0.51cm3, p = 0.01). A not significant higher interobserver variation was found on T1gd (0.4 1 mm) compared to T2 (0.35 mm). The largest variations were found at the tumour‐choroid interface, due to peritumoral enhancement (T1gd: 0.62 mm and T2: 0.5 2 mm). As a result, a larger part of this tumour‐choroid interface appeared to be included on T1gd based GTVs compared to T2, explaining the smaller volumes on T2.Conclusions: The interobserver variation of 0.4 mm on MRI are low with respect to the voxel size of 0.8 mm. We recommend to delineate based on the T1gd‐weighted scans, as choroidal tumour extensions might be missed.Reference1. Ferreira, et al. MR imaging characteristics of uveal melanoma with histopathological validation. Neuroradiology. 2022; 64:171. doi: 10.1007/s00234‐021‐02825‐5.

Real-time Tracking and Classification of Tumor and Nontumor Tissue in Upper Gastrointestinal Cancers Using Diffuse Reflectance Spectroscopy for Resection Margin Assessment

Cancers of the upper gastrointestinal tract remain a major contributor to the global cancer burden. The accurate mapping of tumor margins is of particular importance for curative cancer resection and improvement in overall survival. Current mapping techniques preclude a full resection margin assessment in real time. To evaluate whether diffuse reflectance spectroscopy (DRS) on gastric and esophageal cancer specimens can differentiate tissue types and provide real-time feedback to the operator. This was a prospective ex vivo validation study. Patients undergoing esophageal or gastric cancer resection were prospectively recruited into the study between July 2020 and July 2021 at Hammersmith Hospital in London, United Kingdom. Tissue specimens were included for patients undergoing elective surgery for either esophageal carcinoma (adenocarcinoma or squamous cell carcinoma) or gastric adenocarcinoma. A handheld DRS probe and tracking system was used on freshly resected ex vivo tissue to obtain spectral data. Binary classification, following histopathological validation, was performed using 4 supervised machine learning classifiers. Data were divided into training and testing sets using a stratified 5-fold cross-validation method. Machine learning classifiers were evaluated in terms of sensitivity, specificity, overall accuracy, and the area under the curve. Of 34 included patients, 22 (65%) were male, and the median (range) age was 68 (35-89) years. A total of 14 097 mean spectra for normal and cancerous tissue were collected. For normal vs cancer tissue, the machine learning classifier achieved a mean (SD) overall diagnostic accuracy of 93.86% (0.66) for stomach tissue and 96.22% (0.50) for esophageal tissue and achieved a mean (SD) sensitivity and specificity of 91.31% (1.5) and 95.13% (0.8), respectively, for stomach tissue and of 94.60% (0.9) and 97.28% (0.6) for esophagus tissue. Real-time tissue tracking and classification was achieved and presented live on screen. This study provides ex vivo validation of the DRS technology for real-time differentiation of gastric and esophageal cancer from healthy tissue using machine learning with high accuracy. As such, it is a step toward the development of a real-time in vivo tumor mapping tool for esophageal and gastric cancers that can aid decision-making of resection margins intraoperatively.

Assessment of left atrial fibrosis progression in canines following rapid ventricular pacing using 3D late gadolinium enhanced CMR images.

BackgroundAtrial fibrillation (AF) is associated with extracellular matrix (ECM) remodelling and often coexists with myocardial fibrosis (MF); however, the causality of these conditions is not well established.ObjectiveWe aim to corroborate AF to MF causality by quantifying left atrial (LA) fibrosis in cardiac magnetic resonance (CMR) images after persistent rapid ventricular pacing and subsequent AF using a canine model and histopathological validation.MethodsTwelve canines (9 experimental, 3 control) underwent baseline 3D LGE-CMR imaging at 3T followed by insertion of a pacing device and 5 weeks of rapid ventricular pacing to induce AF (experimental) or no pacing (control). Following the 5 weeks, pacing devices were removed to permit CMR imaging followed by excision of the hearts and histopathological imaging. LA myocardial segmentation was performed manually at baseline and post-pacing to permit volumetric %MF quantification using the image intensity ratio (IIR) technique, wherein fibrosis was defined as pixels > mean LA myocardium intensity + 2SD.ResultsVolumetric %MF increased by an average of 2.11 ± 0.88% post-pacing in 7 of 9 experimental dogs. While there was a significant difference between paired %MF measurements from baseline to post-pacing in experimental dogs (P = 0.019), there was no significant change in control dogs (P = 0.019 and P = 0.5, Wilcoxon signed rank tests). The median %MF for paced animals was significantly greater than that of non-paced dogs at the 5-week post-insertion time point (P = 0.009, Mann Whitney U test). Histopathological imaging yielded an average %MF of 19.42 ± 4.80% (mean ± SD) for paced dogs compared to 1.85% in one control dog.ConclusionPersistent rapid ventricular pacing and subsequent AF leads to an increase in LA fibrosis volumes measured by the IIR technique; however, quantification is limited by inherent image acquisition parameters and observer variability.

Histopathological validation of semi-automated myocardial scar quantification techniques for dark-blood late gadolinium enhancement magnetic resonance imaging.

To evaluate the performance of various semi-automated techniques for quantification of myocardial infarct size on both conventional bright-blood and novel dark-blood late gadolinium enhancement (LGE) images using histopathology as reference standard. In 13 Yorkshire pigs, reperfused myocardial infarction was experimentally induced. At 7 weeks post-infarction, both bright-blood and dark-blood LGE imaging were performed on a 1.5 T magnetic resonance scanner. Following magnetic resonance imaging (MRI), the animals were sacrificed, and histopathology was obtained. The percentage of infarcted myocardium was assessed per slice using various semi-automated scar quantification techniques, including the signal threshold vs. reference mean (STRM, using 3 to 8 SDs as threshold) and full-width at half-maximum (FWHM) methods, as well as manual contouring, for both LGE methods. Infarct size obtained by histopathology was used as reference. In total, 24 paired LGE MRI slices and histopathology samples were available for analysis. For both bright-blood and dark-blood LGE, the STRM method with a threshold of 5 SDs led to the best agreement to histopathology without significant bias (-0.23%, 95% CI [-2.99, 2.52%], P = 0.862 and -0.20%, 95% CI [-2.12, 1.72%], P = 0.831, respectively). Manual contouring significantly underestimated infarct size on bright-blood LGE (-1.57%, 95% CI [-2.96, -0.18%], P = 0.029), while manual contouring on dark-blood LGE outperformed semi-automated quantification and demonstrated the most accurate quantification in this study (-0.03%, 95% CI [-0.22, 0.16%], P = 0.760). The signal threshold vs. reference mean method with a threshold of 5 SDs demonstrated the most accurate semi-automated quantification of infarcted myocardium, without significant bias compared to histopathology, for both conventional bright-blood and novel dark-blood LGE.

Metabolic alterations in the visual pathway of retinitis pigmentosa rats: A longitudinal multimodal magnetic resonance imaging study with histopathological validation.

Because retinitis pigmentosa (RP) has been shown to cause degenerative changes in the entire visual pathway, there is an urgent need to perform longitudinal assessments of RP-induced degeneration and identify imaging protocols to detect this degeneration as early as possible. In this study, we assessed a transgenic rat model of RP by using complementary noninvasive magnetic resonance imaging techniques, namely, proton magnetic resonance spectroscopy (1 H-MRS), to investigate the metabolic changes in RP. Our study demonstrated decreased concentrations and ratios to creatine (Cr) of N-acetylaspartate (NAA), glutamate (Glu), γ-aminobutyric acid (GABA), and taurine (Tau), whereas myo-inositol (Ins) and choline (Cho) were increased in the visual cortex of Royal College of Surgeons (RCS) rats compared with control rats (p < 0.05). Furthermore, with the progression of RP, the concentrations of NAA, Glu, GABA, and Tau, and the ratios of GABA/Cr and Tau/Cr significantly decreased over time, whereas the concentrations of Ins and Cho and the ratio of Ins/Cr significantly increased over time (p < 0.05). In addition, in RCS rats, NAA/Cr decreased significantly from 3 to 4 months postnatal (p < 0.001), and Cho/Cr increased significantly from 4 to 5 months postnatal (p = 0.005). Meanwhile, the 1 H-MRS indicators in 5-month postnatal RCS rats could be confirmed by immunohistochemical staining. In conclusion, with the progression of RP, the metabolic alterations in the visual cortex indicated progressive reprogramming with the decrease of neurons and axons, accompanied by the proliferation of gliocytes.

The Detection Performance of 18 F-Prostate-Specific Membrane Antigen-1007 PET/CT in Primary Prostate Cancer : A Systemic Review and Meta-analysis.

Multiple tools are now available to determine the requirement for a biopsy to diagnose prostate cancer, and PET/CT with radiolabeled prostate-specific membrane antigen (PSMA)-targeting radiotracers has been recommended for detecting primary prostate cancer. Particularly, the radiotracer 18 F-PSMA-1007 was found to be more favorable for primary tumors compared with other PSMA-targeting radiotracers because of its low clearance via the urinary tract and better image resolution. Thus, we performed a systematic review and meta-analysis to more accurately evaluate the detection performance of 18 F-PSMA-1007 PET/CT in primary prostate cancer patients. An update on the databases of PubMed/MEDLINE, EMBASE, and Cochrane Library for comprehensive literature search was performed on September 30, 2021. The pooling detection rate was calculated on a per-patient basis. The pooling median of the SUV max was analyzed from the included studies. Furthermore, the positive predictive value of 18 F-PSMA-1007 PET/CT with pathologic lesions was analyzed using the criterion standard. Twelve studies (540 patients total) were included in the meta-analysis. The overall pooling detection rate of 18 F-PSMA-1007 per patient was 94%, and the pooling median of SUV max located at the intraprostate tumor was 16 (range, 3.7-77.7). The positive predictive value of 18 F-PSMA-1007 per lesion with histopathological validation was 0.90, detecting regional lymph node metastasis was 0.94, and detecting localized prostatic tumors was 0.84. In the current meta-analysis, we revealed the excellent performance of 18 F-PSMA-1007 to detect localized prostatic tumor lesions and regional lymph node metastasis. Moreover, the uptake of localized tumors in primary prostate cancer was nearly liver uptake and may be considered a suspicious malignancy if it was equal to or greater than the liver uptake.

Histo-MRI map study protocol: a prospective cohort study mapping MRI to histology for biomarker validation and prediction of prostate cancer

IntroductionMultiparametric MRI (mpMRI) is now widely used to risk stratify men with a suspicion of prostate cancer and identify suspicious regions for biopsy. However, the technique has modest specificity and...

Artificial double inversion recovery images can substitute conventionally acquired images: an MRI-histology study

Cortical multiple sclerosis lesions are disease-specific, yet inconspicuous on magnetic resonance images (MRI). Double inversion recovery (DIR) images are sensitive, but often unavailable in clinical routine and clinical trials. Artificially generated images can mitigate this issue, but lack histopathological validation. In this work, artificial DIR images were generated from postmortem 3D-T1 and proton-density (PD)/T2 or 3D-T1 and 3D fluid-inversion recovery (FLAIR) images, using a generative adversarial network. All sequences were scored for cortical lesions, blinded to histopathology. Subsequently, tissue samples were stained for proteolipid protein (myelin) and scored for cortical lesions type I-IV (leukocortical, intracortical, subpial and cortex-spanning, respectively). Histopathological scorings were then (unblinded) compared to MRI using linear mixed models. Images from 38 patients (26 female, mean age 64.3 ± 10.7) were included. A total of 142 cortical lesions were detected, predominantly subpial. Histopathology-blinded/unblinded sensitivity was 13.4/35.2% for artificial DIR generated from T1-PD/T2, 14.1/41.5% for artificial DIR from T1-FLAIR, 17.6/49.3% for conventional DIR and 10.6/34.5% for 3D-T1. When blinded to histopathology, there were no differences; with histopathological feedback at hand, conventional DIR and artificial DIR from T1-FLAIR outperformed the other sequences. Differences between histopathology-blinded/unblinded sensitivity could be minified through adjustment of the scoring criteria. In conclusion, artificial DIR images, particularly generated from T1-FLAIR could potentially substitute conventional DIR images when these are unavailable.

Abstract P044: Real-time visualization of tumor cell phenotype and microenvironmental heterogeneity enabled by a hyperspectral fluorescence microendoscope

Abstract Tumor microenvironmental heterogeneity is a major driver of treatment resistance and variability in clinical response to therapy. This heterogeneity arises from variations in cellular phenotypes populating the tumor microenvironment (TME), their spatio-temporal localization and expression of surface markers, often associated with specific biological function – stemness, metabolism, proliferation, immune activation and others. Such features are usually studied through ex vivo immunofluorescence and cytometry to identify cellular phenotypes in TME; however, they cannot be applied in vivo for real time TME analysis. Moreover, current in vivo imaging techniques fail to provide real-time high-resolution visualization of the TME. Routinely employed biopsy tissue sampling through fine needle aspirates is limited by its invasive nature and inability to provide a global and dynamic overview of the TME, thus limiting our ability to study spatiotemporal TME dynamics and identify possible features leading to potentially resistant tumor phenotypes. In this study, we demonstrate the use of a hyperspectral fluorescence microendoscope (HFME) to monitor cellular phenotypes in TME with real-time visualization and high video imaging capability (~17 fps). Current fluorescence video microscopy is limited to simultaneous imaging of no more than 2 molecular markers with potential to be expanded to ~4 markers using dichroic mirrors and point detectors; the HFME demonstrated in this study can currently resolve 6 different molecular markers, simultaneously, using a multichannel linear array detector with potential to expand to 10 or more markers. Using a cocktail of near infra-red fluorophore-antibody conjugates targeted against key molecular (surface) markers of different cells in the TME, we are able to capture real-time TME dynamics at cellular resolution in two pre-clinical models; 1) a xenograft orthotopic mouse model of peritoneal carcinomatosis (disseminated metastases within the abdominal cavity) and imaging epidermal growth factor receptor (EGFR), CD44, CA125 (MUC16), transferrin receptor, Thomsen-Friedenreich carbohydrate antigen (T antigen), and CD45, 2) A syngeneic immunocompetent KPC cell line implanted mouse model of pancreatic ductal adenocarcinoma and imaging CD3, CD4, CD8a and CD45. Imaging on these tumor models was performed pre- and post-sub-therapeutic verteporfin (benzoporphyrin derivative monoacid A) photodynamic therapy (PDT, a cytotoxic light-based therapy). PDT treatment resulted in reduction of cancer cell burden, immune cell infiltration and alterations in their relative spatial localization. The results were confirmed by histopathological validation and ex vivo immunofluorescence staining of tumor tissue sections. Collectively, these results demonstrate the capability of HFME to image cancer cell phenotypes and the tumor microenvironment, in real time in live mice. With the ability to monitor cancer growth and treatment effects at a cellular level, HFME can potentially assist in customizing therapies in a patient-specific manner. Citation Format: Mohammad A. Saad, Bryan Q. Spring, Akilan Palanisami, Eric M. Kercher, Ryan T. Lang, Jason Sutin, Zhiming Mai, Tayyaba Hasan. Real-time visualization of tumor cell phenotype and microenvironmental heterogeneity enabled by a hyperspectral fluorescence microendoscope [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr P044.

Head-to-Head Comparison of 68Ga-FAPI-46 and 18F-FDG PET/CT for Evaluation of Head and Neck Squamous Cell Carcinoma: A Single-Center Exploratory Study.

68Ga-conjugated fibroblast activation protein inhibitor (68Ga-FAPI) has become an attractive agent for PET. This study aimed to compare 68Ga-FAPI-46 PET/CT with 18F-FDG PET/CT for detecting primary cancer and metastatic lesions in patients with head and neck squamous cell carcinoma (HNSCC). Methods: Twelve patients and 28 patients with HNSCC underwent 68Ga-FAPI-46 and 18F-FDG PET/CT for initial staging and recurrence detection, respectively. The concordance and diagnostic accuracy of both tracers were analyzed. Semiquantitative parameters, including SUVmax, SUVmean, and tumor-to-background ratio, were compared. Fibroblast activation protein (FAP) expression tumor volume and total lesion FAP expression of 68Ga-FAPI-46 were compared with metabolic tumor volume and total lesion glycolysis of 18F-FDG, respectively. Differences between semiquantitative parameters were analyzed using paired t testing. Results:68Ga-FAPI-46 PET/CT was 83.3% and 96.4% concordant with 18F-FDG PET/CT for initial staging and recurrence detection, respectively. Eighteen lesions had histopathologic validation, and both tracers displayed 100% sensitivity, 50% specificity, and 94.4% accuracy for lesion-based analysis. FAP expression tumor volume was greater than metabolic tumor volume (P < 0.05), but no significant differences were observed for the other parameters. Conclusion:68Ga-FAPI-46 PET/CT showed good concordance with, and comparable diagnostic performance to, 18F-FDG PET/CT for initial staging and recurrence detection in HNSCC patients.

MR imaging characteristics of uveal melanoma with histopathological validation

PurposeTo evaluate the magnetic resonance imaging (MRI) characteristics of uveal melanoma (UM), to compare them with fundoscopy and ultrasound (US), and to validate them with histopathology.MethodsMR images from 42 UM were compared with US and fundoscopy, and on 14 enucleated cases with histopathology.ResultsA significant relationship between the signal intensity on T1 and pigmentation on histopathology was found (p=0.024). T1 hyperintense UM were always moderately or strongly pigmented on histopathology, while T1-hypointense UM were either pigmented or non-pigmented. Mean apparent diffusion coefficient (ADC) of the UM was 1.16 ± 0.26 × 10−3 mm2/s. Two-thirds of the UM had a wash-out and the remaining a plateau perfusion time-intensity curve (TIC). MRI was limited in evaluating the basal diameter of flat tumors. US tends to show larger tumor prominence (0.5mm larger, p=0.008) and largest basal diameter (1.4mm larger, p<0.001). MRI was good in diagnosing ciliary body involvement, extrascleral extension, and optic nerve invasion, but limited on identifying scleral invasion. An increase of tumor prominence was associated with lower ADC values (p=0.030) and favored a wash-out TIC (p=0.028). An increase of tumor ADC correlated with a plateau TIC (p=0.011).ConclusionsThe anatomical and functional MRI characteristics of UM were comprehensively assessed. Knowing the MRI characteristics of UM is important in order to confirm the diagnosis and to differentiate UM from other intra-ocular lesions and because it has implications for treatment planning. MRI is a good technique to evaluate UM, being only limited in case of flat tumors or on identifying scleral invasion.

Histopathological validation and clinical correlates of hippocampal subfield volumetry based on T2-weighted MRI in temporal lobe epilepsy with hippocampal sclerosis

The objectives of this study were 1) to histologically validate the hippocampal subfield volumetry based on T2-weighted MRI, and 2) to explore its clinical impact on postsurgical memory function and seizure outcome in temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS). We analyzed the cases of 24 patients with medial TLE (12 left, 12 right) and HS who were preoperatively examined with T2-weighted high-resolution MRI. The volume of each hippocampal subfield was calculated with an automatic segmentation of hippocampal subfields (ASHS) program. Hippocampal sclerosis patterns were determined pathologically, and the cross-sectional area and neuronal cell density of the CA1 and CA4 subfields were calculated using tissue specimens. Pre- and postoperative memory evaluations based on the Wechsler Memory Scale-Revised (WMS-R) were performed. We compared the presurgical MRI-based volumes with the pathological measurements in each subfield and then compared them with the change in the patients' neurocognitive function. As a result, there was a significant relationship between the presurgical MRI-based volume of CA4/dentate gyrus (DG) and the cross-sectional area of CA4 calculated with tissue specimens (Spearman's rs = 0.482, p = 0.023), and a similar trend-level correlation was observed in CA1 (rs = 0.455, p = 0.058). Some of MRI-based or pathology-based parameters in the subfields preliminarily showed relationships with the postsurgical memory changes. In conclusion, automated subfield volumetry for patients with hippocampal sclerosis moderately reflects their subfield atrophy and might be useful to predict the postsurgical change of memory function in these patients.

Histopathological validation of safe margin for nephron-sparing surgery based on individual tumor growth pattern

BackgroundTo evaluate the clinicopathologic value of morphological growth patterns of small renal cell carcinoma (sRCC) and determine the actual demand for taking a rim of healthy parenchyma to avoid positive SM.MethodsData was collected from 560 sRCC patients who underwent laparoscopic surgeries from May 2010 to October 2017. One hundred forty-nine cases received nephron-sparing surgery (NSS) and others received radical nephrectomy (RN). All specimens were analyzed separately by two uropathologists, and three morphological growth patterns were identified. The presence of pseudocapsule (PC), surgical margins (SM), and other routine variables were recorded. The relationship between growth patterns and included variables was measured by the χ2 test and Fisher’s exact probability test. Survival outcomes were evaluated by Kaplan-Meier method and the log-rank test.ResultsThe median age of patients was 63.2 years old and the mean tumor diameter was 3.0 cm. Four hundred eighty (85.7%) cases were clear cell RCC and 541 (96.6%) cases were at the pT1a stage. Peritumoral PC was detected in 512 (92.5%) specimens, and the ratio of tumor invasion in PC in infiltration pattern increased obviously than that of the other growth patterns. Similarly, the pT stage was significantly correlated with the infiltration pattern as well. One hundred forty-nine patients underwent NSS and 3 (2.0%) of them showed positive SM after operation. Statistical differences of the 5-year overall survival (OS) and the cancer-specific survival (CSS) existed between different morphological growth patterns, PC status, and pT stages.ConclusionsMorphological growth patterns of sRCC might be used as a potential biomarker to help operate NSS to avoid the risk of positive SM. How to distinguish different morphological growth patterns before operation and the effectiveness of the growth pattern as a novel proposed parameter to direct NSS in sRCC patients deserves further exploration.

Computational Investigation and Histopathological Validation of Interaction Between Stent Graft and Aorta in Retrograde Type A Dissection After TEVAR in Canine Models

Purpose: Retrograde type A dissection (RTAD) after thoracic endovascular aortic repair (TEVAR) has been a major drawback of endovascular treatment. To our knowledge, no studies have simulated and validated aortic injuries caused by stent grafts (SGs) in animal models. Therefore, the aim of this study was to evaluate and quantify the SG–aorta interaction through computational simulations and to investigate the underlying mechanism through histopathological examinations. Methods: Two custom-made Fabulous® (DiNovA Meditech, Hang Zhou, China) SGs were implanted in 2 canine aortas with a 5-mm difference in the distance in landing locations. The aortic geometries were extracted from RTAD and non-RTAD cases. A computational SG model was assembled based on the implanted SG using the software Pro-ENGINEER Wildfire 5.0 (PTC Corporation, Needham, Mass). TEVAR simulations were performed 7 times for each canine model using Abaqus software (Providence, RI, USA), and the maximum aortic stress (MAS) was calculated and compared among the groups. Three months after SG implantation, the canine aortas were harvested, and were examined using hematoxylin and eosin staining and Elastica Van Gieson (EVG) staining to evaluate histopathological changes. Results: In the computational models for both canines, MAS was observed at the proximal bare stent (PBS) at aortic greater curve. The PBS generated higher stress toward the aortic wall than other SG parts did. Moreover, the MAS was significantly higher in canine No.1 than in canine No.2 (0.415±0.210 versus 0.200±0.160 MPa) (p<0.01). Notably, in canine No.1, an RTAD developed at the MAS segment, and histopathological examinations of the segment showed an intimal flap, a false lumen, elastin changes, and medial necrosis. RTAD was not observed in canine No.2. In both SG-covered aortas, medial necrosis, elastic fiber stretching, and inflammatory infiltration were seen. Conclusion: The characteristic MAS distribution remained at the location where the apex of the PBS interacted with the aortic wall at greater curve. RTAD histopathological examinations showed intimal damage and medial necrosis at the proximal landing zone, at the same MAS location in computational simulations. The in vivo results were consistent with the computational simulations, suggesting the MAS at greater curve may cause RTAD, and the potential application of computational simulation in the mechanism study of RTAD.