Postoperative MRI Scans Research Articles

Prospective Outcomes of a Biological Resurfacing Arthroplasty with Fascia Lata Autograft (BioJoint) for the Treatment of Osteoarthritis of the Midtarsal Joint Complex.

To determine the clinical, safety, and radiological outcomes after biological resurfacing arthroplasty for the treatment of osteoarthritis (OA) of one or more joints of the midtarsal joint complex. All prospectively followed patients with OA to one of or multiple joints of the midtarsal joint complex who were operated with a biological resurfacing arthroplasty with a fascia lata autograft (BioJoint procedure) were included. A total of 7 patients were included (5 males, 2 females), with a median age of 52 (interquartile range [IQR] 44-55) years. The primary outcome was the Numeric Rating Scale (NRS) for pain during walking 2 years postoperatively. Range of motion (ROM), revision rates, and complications were assessed. A postoperative MRI scan was performed to assess progression of OA, graft position and ingrowth, and the degree of bone marrow edema. There was a 100% follow-up of the patients (median follow-up: 33 [IQR 26-33] months). The NRS during walking improved from 6 preoperatively to 2 at 2 years postoperatively (P < 0.05). There were no reoperations nor severe complications. The limitations in the ROM remained limited in the majority of the cases. MRI at 2 years of follow-up showed no progression of OA, reduced bone marrow edema, and no loosening of the grafts. Biological resurfacing arthroplasty with a fascia lata autograft (BioJoint procedure) for OA to one or more joints in the midtarsal joint complex showed clinically relevant pain reduction during walking, improvement in clinical and radiological outcomes, and proved to be safe and durable.

Dural reconstruction following resection of ventral and lateral spinal cord meningiomas: Fenestrated Durotomy with Oversized Graft technique

BackgroundMeningiomas, although benign, often require complete resection due to their tendency for recurrence. However, dural reconstruction poses significant challenges, especially in the case of ventral meningiomas. While some reports have highlighted the usefulness of dural reconstruction using an artificial dura mater, no studies have yet confirmed dural canal enlargement through MRI post-surgically. This study aimed to assess the effectiveness of the Fenestrated Durotomy with Oversized Graft (FDOG) technique in cases of meningiomas and other intradural extramedullary tumors and evaluated dural canal dilation through MRI after using an artificial dura mater. MethodsThis retrospective case series included 8 patients who underwent combined resection of intradural extramedullary tumors and dural repair using the FDOG technique. An artificial dura mater larger than that resected was inserted into the dural defect resulting from complete tumor resection on the ventral or lateral side of the spinal cord. The new dura mater was secured with a single dorsal suture. The dural incision was closed using watertight sutures following standard procedure. Measurement of the extent of dural canal enlargement was achieved via pre- and postoperative MRI scans. ResultsNone of the patients required additional treatments or lumbar drainage. All achieved independent ambulation without complications, and imaging tests indicated satisfactory dural expansion without signs of cerebrospinal fluid leakage. ConclusionsThe proposed method for dural repair in cases involving large dural defects on the ventral or lateral side of the spinal cord was shown to be a straightforward and effective approach with minimal postoperative complications.

P21.01.A EPIDEMIOLOGY OF ISCHEMIC LESIONS AFTER RESECTION OF LOW-GRADE GLIOMAS

Abstract BACKGROUND Diffuse low-grade gliomas are slow-growing malignant brain tumors that mainly affect people in their 30s and 40s, usually resulting in death within a decade. The standard treatment is surgery, which has a moderate risk of neurological sequelae. Clinical experience indicates that not all sequels are directly related to the resected area but rather caused by collateral damage, such as tissue- and vascular damages at the surgical site, causing ischemic lesions in the surrounding tissue. In this study, the epidemiology of these lesions is investigated, in terms of how common they are and how they are related to the size, type and location of the tumor. MATERIAL AND METHODS One hundred and sixty-six patients who underwent resection for grade II glioma (WHO 2007 or 2016) between 2012 and 2017 at any of nine hospitals in Sweden and Norway and had a postoperative MRI scan including diffusion-weighted imaging within three days after surgery, were included in this study. Lesions were segmented on the b1000 image, using the ADC and T1 image to exclude hyperintense areas caused by other factors than ischemia. Statistical analyses were performed using IBM SPSS Statistics version 27.0 (IBM Corp., Armonk, NY, USA). Analyses were carried out with ischemic lesion size as a continuous variable, and since the volumes were not normally distributed, non-parametric tests were used. RESULTS Ischemic lesions were found in 146 out of 166 (88%) cases, the median volume of the segmented lesions was 1.9 ml, with an interquartile range (IQR) of 0.95-4.5 ml. Patients with new or worsened deficits did have significantly larger ischemic volumes than does who did not (1.7 vs 2.8 ml, p=0.03). Ischemic volume was significantly correlated to both pre- and post-operative tumor volume (Spearmans rho = 0.370 and 0.304, p&amp;lt;0.001). No difference in ischemic volume was found between astrocytoma and oligodendroglioma, based on reported histopathologic diagnosis (p=0.43) or molecular status (p=0.44), neither between main tumor local (frontal (60%) vs temporal (19%), parietal (8%) or insular (12%), p&amp;gt;0.37). CONCLUSION Ischemic lesions after glioma resection are very common, but mostly small and restricted to a region close to the resection cavity. Large ischemic regions were associated with new or worsened neurological deficits and were mostly found in association with large tumors. More fine-tuned measures might be needed to find potential associations between tumor local and ischemic lesions.

Retinal vascular and structural recovery analysis by optical coherence tomography angiography after endoscopic decompression in sellar/parasellar tumors

We assessed the potential retinal microcirculation alterations for postoperative visual recovery in sellar/paraseller tumor patients with Optical Coherence Tomography Angiography (OCT-A). Two hundred ten eyes with sellar/parasellar tumor for which preoperative and postoperative (3 months) MRI Scans, Visual Acuity Test, Optical Coherence Tomography (OCT), OCT-A and, Visual Field Test data were available, besides 92 healthy eyes were evaluated. In the preoperative phase, significant reductions were observed in retinal vascular densities in various regions, including the Superficial Retinal Capillary Plexus (SRCP) (whole: p < 0.001, fovea: p = 0.025, parafovea: p < 0.001), Deep Retinal Capillary Plexus (DRCP) (whole: p < 0.001, fovea: p = 0.003, parafovea: p < 0.001), Peripapillary Vascular Density (PVD) (whole: p = 0.045, peripapillary: p < 0.001, nasal: p < 0.001, inferior: p < 0.001, temporal: p < 0.001), and Retinal Nerve Fiber Layer (RNFL) (nasal: p = 0.024, inferior: p < 0.001, temporal: p < 0.001, superior: p < 0.001) compared to the healthy control group. After surgery, the postoperative data of patients without chiasmal distortion were compared to their preoperative data. In the postoperative evaluation, significant increases were observed in vascular densities in patients without chiasmal distortion in the SRCP (whole: p < 0.001, parafovea: p = 0.045), DRCP (whole: p = 0.007, fovea: p = 0.006, parafovea: p = 0.040), PVD (peripapillary: p = 0.010, inferior: p < 0.001, temporal: p < 0.001, superior: p < 0.001), and RNFL (nasal: p = 0.011, inferior: p = 0.034, temporal: p = 0.046, superior: p = 0.011). Furthermore, significant associations were observed in the ROC analysis between the postoperative Visual Field Mean Deviation (VFMD) and SRCP (whole AUC = 0.793, p < 0.001, cut-off = 51.45, parafovea AUC = 0.820, p < 0.001, cut-off = 53.95), DRCP (whole AUC = 0.818, p < 0.001, cut-off = 55.95, parafovea AUC = 0.820, p < 0.001, cut-off = 59.05), PVD (temporal AUC = 0.692, p < 0.001, cut-off = 55.10), and RNFL (whole AUC = 0.690, p = 0.001, cut-off = 119.5, inferior AUC = 0.712, p < 0.001, cut-off = 144.75). These findings indicate a potential role of pre and post-operative OCT-A measurements in the assessment of surgical timing and postoperative visual recovery in patients with or without optic chiasm distortion.

Impact of surgical variables on residual glandular tissue in risk-reducing mastectomies: Results of a retrospective monocentric study from a center of the German consortium for hereditary breast and ovarian cancer

PurposeResidual glandular tissue (RGT) after risk reducing mastectomy (RRME) is associated with a risk of developing breast cancer for women with a familial predisposition. We aim to examine various surgery-related variables to make risk more easily assessable and to aid in decision-making. Materials and methodsPre- and postoperative breast MRI scans from 2006 to 2021 of patients with proven pathogenic mutation were included. The postoperative remaining skin flap was recorded using distance measurements at 8 equally distributed clockwise points and retromamillary. Each breast was volumetrized, as well as existing RGT. Patient-related covariates were further recorded and their influence on RGT was investigated uni- and multivariately. Results81 patients (49 with BRCA1, 24 with BRCA2, 9 with other mutations), who were on average 39 years old, had 117 breasts analyzed. The mean follow-up was 71 months. In multivariate analysis, the independent variable skin flap thickness had a positive effect (p ≤ 0.01), while surgeon experience negatively affected RGT (p ≤ 0.05). The incision type was found to impact RGT as well, with nipple-sparing mastectomy (NSM) with inframammary fold incision leading to more RGT (p ≤ 0.01 – p ≤ 0.05), and skin-sparing mastectomy (SSM) with an inverted T incision leading to less (p ≤ 0.01). ConclusionDifferent surgical variables have an impact on postoperative RGT, which is an important tool to quantify the risk of developing breast cancer after RRME. In order to effectively consider these variables in future preoperative/intraoperative management, they must be carefully taken into account.

Poster 260: Influence of Donor Demographics on Graft Survival following Knee Osteochondral Allograft Transplantation

Objectives: To evaluate whether donor and recipient factors such as donor age, sex mismatch, and time from death to graft implantation affect graft survival following knee osteochondral allograft (OCA) transplantation. Methods: Patients undergoing OCA transplantation in the knee from 2003-2016 were prospectively followed. Inclusion criteria consisted of primary OCA transplantation and minimum 2-year follow-up. Patient and donor demographic data were collected. Patients were evaluated for failure, defined as (1) subchondral collapse of the OCA as confirmed on postoperative MRI scans, or via second-look arthroscopy in the setting of persistent symptoms, (2) removal or revision of the primary OCA, or (3) conversion to arthroplasty. Multivariate cox proportional hazards modelling was utilized to evaluate associations between demographic variables and graft failure. Results: A total of 220 patients undergoing OCA transplantation met inclusion criteria and were followed for a mean of 5.9 ± 2.8 years (range: 2.0 – 16.3, Table 1). The most common concomitant procedure was meniscal allograft transplantation (Table 2). A mismatch in donor and recipient sex was present for significantly more female patients (65%) than male patients (10%, p &lt; 0.001). The mean days from donor death until implantation was 24.1 days (range: 15 – 28). Thirty-nine patients (18%) met criteria for graft failure at a mean of 4.3 ± 3.2 years (Table 3). Log-rank testing did not determine a difference in survivability between those with a donor-recipient sex mismatch for female or male patients (P = .130 and .831, respectively). Upon multivariate cox regression, no association existed between donor-recipient sex mismatch or time from donor death to implantation with graft survival. Of note, increased donor age was associated with failure for female patients (P = .020) and trended towards significance in males (P = .166). Conclusions: OCA graft survival appears to be most strongly influenced by donor age. In contrast to previous historic data, no substantial survival difference was noted for sex mismatched donors and recipients. These data can help inform graft selection and outcome optimization following OCA. [Table: see text][Table: see text][Table: see text]

P.116 Anatomical fiducials used to quantify localization and registration accuracy in deep brain stimulation

Background: Studies of deep brain stimulation (DBS) require accurate electrode localization and image registration. We used anatomical fiducials to investigate localization and registration errors in patients who underwent subthalamic nucleus (STN) DBS for Parkinson’s disease (PD). Methods: We conducted a retrospective analysis of patients who underwent bilateral STN DBS for PD. Pre and post operative MRI scans were non-linearly normalized to a standard template (MNI152NLin2009bAsym). Four raters localized DBS electrodes (Lead-DBS), the anterior commissure (AC) and posterior commissure (PC). Errors between rater localizations were calculated (fiducial localization error; FLE). We transformed AC and PC coordinates from template to patient space to calculate the fiducial registration error (FRE)Results: Ninety-nine patients were analyzed, with a median FLE of 0.76mm, 0.74mm, 0.71mm and 0.66mm for the right electrode, left electrode, AC and PC respectively (no significant difference, Wilcoxon sign rank). The median FRE was 1.59mm for AC and 1.21mm for PC, significantly higher than FLE at those coordinates (Wilcoxon sign rank, p&lt;0.001). Conclusions: Raters can accurately localize DBS electrodes, AC and PC from clinical images with sub-millimetric accuracy. Higher FREs at AC and PC suggested registration errors may contribute more than localization errors to electrode uncertainty in a common space.

Deep Machine Learning Algorithms in Glioblastoma (GBM) MRI evaluation (PL4.005)

<h3>Objective:</h3> To test the reliability of automatic segmentation models on post-operative MRIs in glioblastoma evaluation. <h3>Background:</h3> The extent of tumor resection in glioblastoma is an independent prognostic factor associated with clinical outcomes. Because radiological assessment to identify residual tumoral components can be time-consuming and subject to inter-rater variability, the implementation of artificial intelligence (AI) may improve radiological assessment. Hereby, we evaluate performance of different automatic brain tumor segmentation algorithms trained on pre-operative MRI datasets, on post-operative MRI scans of patients with glioblastoma. <h3>Design/Methods:</h3> We evaluated the performance of ten different deep-learning models designed for automated brain tumor segmentation. Models were trained using a publicly available dataset from the Brain Tumor Segmentation (BRaTS) Challenge 2020 and was tested in our institutional MRI scans including pre-operative and post-operative MRI examinations. Semiautomatic segmentation was performed in the institutional scans and was used as the ground truth. Dice Similarity Coefficient (DSC) was used to compare each model’s performance against the ground truth. <h3>Results:</h3> A total of 329 MR examinations were used for training purposes and a separate 100 scans were used to test the deep-learning algorithms. Overall, models demonstrated better performance on pre-operative scans. Among post-operative MRI studies, Knowledge Distillation algorithm exhibited the best performance with a DSC score of 0.836 for whole tumor segmentation. When evaluating specific regions within the tumor, Knowledge Distillation demonstrated a DSC of 0.82 for the FLAIR hyperintense region, 3D Dilated Multi-Fiber Network achieved a DSC of 0.88 in the contrast-enhancing tumoral region, and 3D U-Net exhibited the highest DCS for the non-enhancing core (0.84). <h3>Conclusions:</h3> Deep machine learning has the potential to quantify enhancing and FLAIR volumes in brain MRI from glioblastoma patients with high accuracy. Current automatic segmentation models can perform automatic segmentation on post-operative MRI scans with an 88% accuracy. Further investigations are needed to improve this promising AI technology. <b>Disclosure:</b> An immediate family member of Dr. Zhu has stock in Abbott lab. The institution of Dr. Zhu has received research support from NRG NIH. The institution of Dr. Zhu has received research support from Novocure, Inc. The institution of Dr. Zhu has received research support from Five Prime pharmaceutical. The institution of Dr. Zhu has received research support from Denovo, inc. The institution of Dr. Zhu has received research support from Boston Biomedical Sumitomo Dainippon Pharma Global Oncology. The institution of Dr. Zhu has received research support from CNS pharmaceutical. Mr. HSIEH has nothing to disclose. Ms. Kabir has nothing to disclose. Dr. Nunez has nothing to disclose. Carlos Rodriguez Quintero has nothing to disclose. Dr. Cai has nothing to disclose. Dr. Hsu has nothing to disclose. Dr. Arevalo has nothing to disclose. Kangyi Zhao has nothing to disclose. Jackie Jiaqi Zhang has nothing to disclose. Roy Riascos-Castaneda has nothing to disclose. The institution of Dr. Jiang has received research support from NIH. The institution of Dr. Jiang has received research support from CPRIT. The institution of Dr. Jiang has received research support from NSF. shayan shams has nothing to disclose.

Same but different. Incidental and symptomatic lower grade gliomas show differences in molecular features and survival

PurposeData on differences in overall survival and molecular characteristics between incidental (iLGG) and symptomatic lower grade Glioma (sLGG) are limited. The aim of this study was to investigate differences between patients with iLGG and sLGG.MethodsAll adult patients with a histologically proven diffuse (WHO°II) or anaplastic (WHO°III) glioma who underwent their first surgery at the authors’ institution between 2010 and 2019 were retrospectively included. Tumor volume on pre- and postoperative MRI scans was determined. Clinical and routine neuropathological data were gained from patients’ charts. If IDH1, ATRX and EGFR were not routinely assessed, they were re-determined.ResultsOut of 161 patients included, 23 (14%) were diagnosed as incidental findings. Main reasons for obtaining MRI were: headache(n = 12), trauma(n = 2), MRI indicated by other departments(n = 7), staging examination for cancer(n = 1), volunteering for MRI sequence testing(n = 1). The asymptomatic patients were significantly younger with a median age of 38 years (IqR28-48) vs. 50 years (IqR38-61), p = 0.011. Incidental LGG showed significantly lower preoperative tumor volumes in T1 CE (p = 0.008), FLAIR (p = 0.038) and DWI (p = 0.028). Incidental LGG demonstrated significantly lower incidence of anaplasia (p = 0.004) and lower expression of MIB-1 (p = 0.008) compared to sLGG. IDH1-mutation was significantly more common in iLGG (p = 0.024). Incidental LGG showed a significantly longer OS (mean 212 vs. 70 months, p = 0.005) and PFS (mean 201 vs. 61 months, p = 0.001) compared to sLGG.ConclusionOur study is the first to depict a significant difference in molecular characteristics between iLGG and sLGG. The findings of this study confirmed and extended the results of previous studies showing a better outcome and more favorable radiological, volumetric and neuropathological features of iLGG.

Changes in psoas and posterior paraspinal muscle morphology after standalone lateral lumbar interbody fusion: a quantitative MRI-based analysis.

Standalone lateral lumbar interbody fusion (SA-LLIF) without posterior instrumentation can be an alternative to 360° fusion in selected cases. This study aimed to investigate quantitative changes in psoas and paraspinal muscle morphology that occur on index levels after SA-LLIF. Patients undergoing single- or multi-level SA-LLIF at L2/3 to L4/5 who had preoperative and postoperative lumbar MRI scans, the latter performed between 3 and 18months after surgery for any reason, were retrospectively included. Muscle measurements were performed of the psoas and posterior paraspinal muscles (PPM; erector spinae and multifidus) on index levels using manual segmentation and an automated pixel intensity threshold method to differentiate muscle from fat signal. Changes in the total cross-sectional area (TCSA), the functional cross-sectional area (FCSA), and the percentage of fat infiltration (FI) of these muscles were assessed. A total of 67 patients (55.2% female, age 64.3 ± 10.6years, BMI 26.9 ± 5.0kg/m2) with 125 operated levels were included. Follow-up MRI scans were performed after an average of 8.7 ± 4.6months, primarily for low back pain. Psoas muscle parameters did not change significantly, irrespective of the approach side. Among PPM parameters, the mean TCSA at L4/5 (+ 4.8 ± 12.4%; p = 0.013), and mean FI at L3/4 (+ 3.1 ± 6.5%; p = 0.002) and L4/5 (+ 3.0 ± 7.0%; p = 0.002) significantly increased. Our study demonstrated that SA-LLIF did not alter psoas muscle morphology, underlining its minimally invasive nature. However, FI of PPM significantly increased over time despite the lack of direct tissue damage to posterior structures, suggesting a pain-mediated response and/or the result of segmental immobilization.

Studyof the microstructure of brain white matter in medial temporal lobe epilepsy based on diffusion tensor imaging.

To compare the white matter (WM) asymmetry in left and right medial temporal lobe epilepsy (mTLE) with and without hippocampal sclerosis (HS+, HS-) and assess the correlation of preoperative asymmetry and the dynamics of WM fibers with surgical outcomes. Preoperative MRI scans were collected from 58 mTLE patients (40 HS+, 18 HS-); 15 (11 HS+, 4 HS-) then underwent postoperative MRI scans. DTI parameters, including the fractional anisotropy (FA), mean diffusion coefficient (MD), axial diffusion coefficient (AD), and radial diffusion coefficient (RD), were extracted from 20 paired WM tracts by PANDA based on the JHU WM tractography atlas. The bilateral cerebral parameters and the pre- to postoperative changes in the DTI parameters of specific fiber tracts were compared. The asymmetry indexes (AIs) of paired fibers were also analyzed. There were fewer asymmetrical WM fibers in HS- patients than in HS+ patients. The pattern of WM asymmetry differed between left and right mTLE patients. Differences in the FA AI of the inferior fronto-occipital fasciculus and inferior longitudinal fasciculus (ILF) were found in left HS+ patients with different surgical outcomes. All mTLE patients exhibited decreases in FA and increases in MD and RD in specific ipsilateral WM fibers. In International League Against Epilepsy (ILAE) grade 1 patients, the MD values in the ipsilateral CGH increased over time, whereas the RD values in the ipsilateral ILF and the AD values in the ipsilateral ILF and UNC decreased. In ILAE grade 2-5 patients, the FA values in the ipsilateral cingulate gyrus part of the cingulum (CGC) increased over time. The WM tract asymmetry was more extensive in HS+ patients than in HS- patients. The preoperative WM fiber AIs in left HS+ patients may be useful for surgical prognosis. Additionally, pre- to postoperative changes in WM fibers may help predict surgical outcomes.

Dissociation of Broca's area from Broca's aphasia in patients undergoing neurosurgical resections.

Broca's aphasia is a syndrome of impaired fluency with retained comprehension. The authors used an unbiased algorithm to examine which neuroanatomical areas are most likely to result in Broca's aphasia following surgical lesions. Patients were prospectively evaluated with standardized language batteries before and after surgery. Broca's area was defined anatomically as the pars opercularis and triangularis of the inferior frontal gyrus. Broca's aphasia was defined by the Western Aphasia Battery language assessment. Resections were outlined from MRI scans to construct 3D volumes of interest. These were aligned using a nonlinear transformation to Montreal Neurological Institute brain space. A voxel-based lesion-symptom mapping (VLSM) algorithm was used to test for areas statistically associated with Broca's aphasia when incorporated into a resection, as well as areas associated with deficits in fluency independent of Western Aphasia Battery classification. Postoperative MRI scans were reviewed in blinded fashion to estimate the percentage resection of Broca's area compared to areas identified using the VLSM algorithm. A total of 289 patients had early language evaluations, of whom 19 had postoperative Broca's aphasia. VLSM analysis revealed an area that was highly correlated (p < 0.001) with Broca's aphasia, spanning ventral sensorimotor cortex and supramarginal gyri, as well as extending into subcortical white matter tracts. Reduced fluency scores were significantly associated with an overlapping region of interest. The fluency score was negatively correlated with fraction of resected precentral, postcentral, and supramarginal components of the VLSM area. Broca's aphasia does not typically arise from neurosurgical resections in Broca's area. When Broca's aphasia does occur after surgery, it is typically in the early postoperative period, improves by 1 month, and is associated with resections of ventral sensorimotor cortex and supramarginal gyri.

Contribution of White Matter Fiber Bundle Damage to Language Change After Surgery for Temporal Lobe Epilepsy.

In medically refractory temporal lobe epilepsy (TLE), 30%-50% of patients experience substantial language decline after resection in the language-dominant hemisphere. In this study, we investigated the contribution of white matter fiber bundle damage to language change at 3 and 12 months after surgery. We studied 127 patients who underwent TLE surgery from 2010 to 2019. Neuropsychological testing included picture naming, semantic fluency, and phonemic verbal fluency, performed preoperatively and 3 and 12 months postoperatively. Outcome was assessed using reliable change index (RCI; clinically significant decline) and change across timepoints (postoperative scores minus preoperative scores). Functional MRI was used to determine language lateralization. The arcuate fasciculus (AF), inferior fronto-occipital fasciculus (IFOF), inferior longitudinal fasciculus, middle longitudinal fasciculus (MLF), and uncinate fasciculus were mapped using diffusion MRI probabilistic tractography. Resection masks, drawn comparing coregistered preoperative and postoperative T1 MRI scans, were used as exclusion regions on preoperative tractography to estimate the percentage of preoperative tracts transected in surgery. Chi-squared assessments evaluated the occurrence of RCI-determined language decline. Independent sample t tests and MM-estimator robust regressions were used to assess the impact of clinical factors and fiber transection on RCI and change outcomes, respectively. Language-dominant and language-nondominant resections were treated separately for picture naming because postoperative outcomes were significantly different between these groups. In language-dominant hemisphere resections, greater surgical damage to the AF and IFOF was related to RCI decline at 3 months. Damage to the inferior frontal subfasciculus of the IFOF was related to change at 3 months. In language-nondominant hemisphere resections, increased MLF resection was associated with RCI decline at 3 months, and damage to the anterior subfasciculus was related to change at 3 months. Language-dominant and language-nondominant resections were treated as 1 cohort for semantic and phonemic fluency because there were no significant differences in postoperative decline between these groups. Postoperative seizure freedom was associated with an absence of significant language decline 12 months after surgery for semantic fluency. We demonstrate a relationship between fiber transection and naming decline after temporal lobe resection. Individualized surgical planning to spare white matter fiber bundles could help to preserve language function after surgery.

The impact of temporal lobe epilepsy surgery on picture naming and its relationship to network metric change

BackgroundAnterior temporal lobe resection (ATLR) is a successful treatment for medically-refractory temporal lobe epilepsy (TLE). In the language-dominant hemisphere, 30%- 50% of individuals experience a naming decline which can impact upon daily life. Measures of structural networks are associated with language performance pre-operatively. It is unclear if analysis of network measures may predict post-operative decline. MethodsWhite matter fibre tractography was performed on preoperative diffusion MRI of 44 left lateralised and left resection individuals with TLE to reconstruct the preoperative structural network. Resection masks, drawn on co-registered pre- and post-operative T1-weighted MRI scans, were used as exclusion regions on pre-operative tractography to estimate the post-operative network. Changes in graph theory metrics, cortical strength, betweenness centrality, and clustering coefficient were generated by comparing the estimated pre- and post-operative networks. These were thresholded based on the presence of the connection in each patient, ranging from 75% to 100% in steps of 5%. The average graph theory metric across thresholds was taken.We incorporated leave-one-out cross-validation with smoothly clipped absolute deviation (SCAD) least absolute shrinkage and selection operator (LASSO) feature selection and a support vector classifier to assess graph theory metrics on picture naming decline. Picture naming was assessed via the Graded Naming Test preoperatively and at 3 and 12 months post-operatively and the outcome was classified using the reliable change index (RCI) to identify clinically significant decline. The best feature combination and model was selected using the area under the curve (AUC). The sensitivity, specificity and F1-score were also reported. Permutation testing was performed to assess the machine learning model and selected regions difference significance. ResultsA combination of clinical and graph theory metrics were able to classify outcome of picture naming at 3 months with an AUC of 0.84. At 12 months, change in strength to cortical regions was best able to correctly classify outcome with an AUC of 0.86. Longitudinal analysis revealed that betweenness centrality was the best metric to identify patients who declined at 3 months, who will then continue to experience decline from 3 to 12 months. Both models were significantly higher AUC values than a random classifier. ConclusionOur results suggest that inferred changes of network integrity were able to correctly classify picture naming decline after ATLR. These measures may be used to prospectively to identify patients who are at risk of picture naming decline after surgery and could potentially be utilised to assist tailoring the resection in order to prevent this decline.

NIMG-40. RAPID EARLY PROGRESSION (REP) OF GLIOBLASTOMA IS AN INDEPENDENT NEGATIVE PROGNOSTIC FACTOR: RESULTS FROM A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract INTRODUCTION In patients with newly-diagnosed glioblastoma, rapid early progression (REP) refers to tumour regrowth between surgery and postoperative chemoradiotherapy. This systematic review and meta-analysis appraised published data on REP to better characterise and understand it. METHODS Systematic searches of MEDLINE, EMBASE and the Cochrane database from inception to 21/10/21. Studies describing the incidence of REP – tumour growth between the postoperative MRI scan and pre-radiotherapy MRI scan in newly-diagnosed glioblastoma, were included. The primary outcome was REP incidence. RESULTS From 1590 search results, 9 studies were included with 716 patients. The median age was 56.9 years (IQR 54.0-58.8 years). There was a male predominance with a median male-to-female ratio of 1.4 (IQR 1.1-1.5). The median number of days between MRI scans was 34 days (IQR 18-45 days). The mean incidence rate of REP was 45.9% (range 19.3%-72.0%) and significantly lower in studies employing functional imaging to define REP (p&amp;lt; 0.001). REP/non-REP groups were comparable with respect to age (p=0.99), gender (p=0.33) and time between scans (p=0.81). REP was associated with shortened overall survival (HR 1.78, 95% CI 1.30-2.43, p&amp;lt; 0.001), shortened progression-free survival (HR 1.78, 95% CI 1.30-2.43, p&amp;lt; 0.001), subtotal resection (OR 6.96, 95% CI 4-51-10.73, p&amp;lt; 0.001) and IDH wildtype versus mutant tumours (OR 0.20, 95% CI 0.02-0.38, p=0.03). MGMT promoter methylation was not associated with REP (OR 1.29, 95% CI 0.72-2.28, p=0.39). CONCLUSIONS REP occurs in almost half of patients with newly-diagnosed glioblastoma and has a strongly negative prognostic effect. Future studies should investigate its biology and effective treatment strategies.

INNV-29. MULTISPECTRAL ANALYSIS FOR INTRA-OPERATIVE CHARACTERIZATION OF BRAIN TUMOURS, MARGINS OF RESECTION, AND ELOQUENT AREAS ACTIVATION – PRELIMINARY RESULTS

Abstract BACKGROUND The identification of intrinsic brain tumours’ boundaries and their anatomical relationship with eloquent connectomes is one of the main challenges in neurosurgery. Several new intra-operative spectroscopic technologies have been recently investigated for this purpose. Multispectral imaging (MSI) analysis is based on analysis of reflected light, divided in specific wavelengths ranges across the electromagnetic spectrum. By doing so, it can identify wavelengths invisible to the naked eye, and make them visible by applying specific filters. METHODS We have used MSI to acquire intraoperative images during brain tumours surgeries. The MSI camera has been adapted to be connected to the intra-operative microscope and acquire a stack of images of different spectra to be analysed on a separate time. The focus of the images acquisition includes tumour structure, its margins, and eloquent connectomes during awake surgery or neurostimulation to analyse the possibility of different perfusion signal during activation. Image segmentation using K-mean clustering has been used to detect structural information and identify tumour’s area and tumour’s margins, while oxygen maps have been created using linear least squares regression to detect areas of metabolic activity. RESULTS Twenty-three patients have been enrolled in the current study at the time of this submission. We have analysed the intra-operative acquisition using intra-operative microscope picture, pre- and post-operative MRI scan, and neurophysiological findings as ground truth. Our preliminary results show that MSI is a potential additional technology to visually show tumour core, margins, and different degree of perfusions on the tissues analysed during tumour surgery. Although on a very limited subgroup of patients, MSI seems to be reliable in identify eloquent areas activation during awake surgery. These results are promising and warrant more data acquisition to be confirmed.

SURG-17. PROGNOSIS IN IDH-MUTANT GLIOMA: THE ROLE OF EXTENT-OF-RESECTION, AGE AND TUMOR GRADE

Abstract BACKGROUND Evidence suggests that smaller residual tumor volumes after initial surgery are associated with longer survival in patients with astrocytoma, IDH-mutant, grade II. For IDH-mutant glioma of higher grade but also for oligodendroglioma, IDH-mutant, and 1p/19q codeleted, the impact of residual tumor volume on survival is unclear. This could be related to the limited follow-up of patients with oligodendroglioma that typically have long overall survival. We expanded a previously published series of patients increase the duration of follow-up and the spectrum of tumor grades. METHODS Single center observational cohort study of patients with adult-type diffuse glioma, IDH-mutant, all WHO-2021 grades, from 2003 to 2021 . Molecular characteristics were assessed by next-generation targeted sequencing. Tumor volumes were calculated by semi-automatic 3D segmentation on pre- and postoperative MRI-scans. Associations between prognostic factors and survival were assessed using univariate and multivariate Cox proportional hazards models. RESULTS 384 patients with IDH-mutant glioma (174 oligodendroglioma, 212 astrocytoma) were followed for a median of 7 years. Median age at diagnosis was 41 years (IQR 33 – 55). Significant prognostic factors for survival were Karnofsky performance status, 1p19q-status and post-operative tumor volume. Smaller post-operative tumor volume was associated with better survival, both in astrocytoma and oligodendroglioma. Age, tumor grade and MRI-contrast enhancement were not associated with survival. CONCLUSION Lower residual tumor volume after first surgery is a strong prognostic factor in all IDH-mutant glioma subgroups, even in patients with very small residual tumor. Importantly, age and histological tumor grade were not significantly associated with survival. The data serves as further support for optimal initial resections of tumors suspected for IDH-mutant glioma, also in oligodendroglioma.

Post-operative glioblastoma multiforme segmentation with uncertainty estimation.

Segmentation of post-operative glioblastoma multiforme (GBM) is essential for the planning of Tumor Treating Fields (TTFields) treatment and other clinical applications. Recent methods developed for pre-operative GBM segmentation perform poorly on post-operative GBM MRI scans. In this paper we present a method for the segmentation of GBM in post-operative patients. Our method incorporates an ensemble of segmentation networks and the Kullback-Leibler divergence agreement score in the objective function to estimate the prediction label uncertainty and cope with noisy labels and inter-observer variability. Moreover, our method integrates the surgery type and computes non-tumorous tissue delineation to automatically segment the tumor. We trained and validated our method on a dataset of 340 enhanced T1 MRI scans of patients that were treated with TTFields (270 scans for train and 70 scans for test). For validation, we developed a tool that uses the uncertainty map along with the segmentation result. Our tool allows visualization and fast editing of the tissues to improve the results dependent on user preference. Three physicians reviewed and graded our segmentation and editing tool on 12 different MRI scans. The validation set average (SD) Dice scores were 0.81 (0.11), 0.71 (0.24), 0.64 (0.25), and 0.68 (0.19) for whole-tumor, resection, necrotic-core, and enhancing-tissue, respectively. The physicians rated 72% of the segmented GBMs acceptable for treatment planning or better. Another 22% can be edited manually in a reasonable time to achieve a clinically acceptable result. According to these results, the proposed method for GBM segmentation can be integrated into TTFields treatment planning software in order to shorten the planning process. To conclude, we have extended a state-of-the-art pre-operative GBM segmentation method with surgery-type, anatomical information, and uncertainty visualization to facilitate a clinically viable segmentation of post-operative GBM for TTFields treatment planning.

Factors associated with an increased risk of developing postoperative symptomatic lumbar spondylolisthesis after decompression surgery: an explorative two-centre international cohort study

PurposeSymptomatic lumbar spinal stenosis can be treated with decompression surgery. A recent review reported that, after decompression surgery, 1.6–32.0% of patients develop postoperative symptomatic spondylolisthesis and may therefore be indicated for lumbar fusion surgery. The latter can be more challenging due to the altered anatomy and scar tissue. It remains unclear why some patients get recurrent neurological complaints due to postoperative symptomatic spondylolisthesis, though some associations have been suggested. This study explores the association between key demographic, biological and radiological factors and postoperative symptomatic spondylolisthesis after lumbar decompression.MethodsThis retrospective cohort study included patients who had undergone lumbar spinal decompression surgery between January 2014 and December 2016 at one of two Spine Centres in the Netherlands or Switzerland and had a follow-up of two years. Patient characteristics, details of the surgical procedure and recurrent neurological complaints were retrieved from patient files. Preoperative MRI scans and conventional radiograms (CRs) of the lumbar spine were evaluated for multiple morphological characteristics. Postoperative spondylolisthesis was evaluated on postoperative MRI scans. For variables assessed on a whole patient basis, patients with and without postoperative symptomatic spondylolisthesis were compared. For variables assessed on the basis of the operated segment(s), surgical levels that did or did not develop postoperative spondylolisthesis were compared. Univariable and multivariable logistic regression analyses were used to identify associations with postoperative symptomatic spondylolisthesis.ResultsSeven hundred and sixteen patients with 1094 surgical levels were included in the analyses. (In total, 300 patients had undergone multilevel surgery.) ICCs for intraobserver and interobserver reliability of CR and MRI variables ranged between 0.81 and 0.99 and 0.67 and 0.97, respectively. In total, 66 of 716 included patients suffered from postoperative symptomatic spondylolisthesis (9.2%). Multivariable regression analyses of patient-basis variables showed that being female [odds ratio (OR) 1.2, 95%CI 1.07–3.09] was associated with postoperative symptomatic spondylolisthesis. Higher BMI (OR 0.93, 95%CI 0.88–0.99) was associated with a lower probability of having postoperative symptomatic spondylolisthesis.Multivariable regression analyses of surgical level-basis variables showed that levels with preoperative spondylolisthesis (OR 17.30, 95%CI 10.27–29.07) and the level of surgery, most importantly level L4L5 compared with levels L1L3 (OR 2.80, 95%CI 0.78–10.08), were associated with postoperative symptomatic spondylolisthesis; greater facet joint angles (i.e. less sagittal-oriented facets) were associated with a lower probability of postoperative symptomatic spondylolisthesis (OR 0.97, 95%CI 0.95–0.99).ConclusionBeing female was associated with a higher probability of having postoperative symptomatic spondylolisthesis, while having a higher BMI was associated with a lower probability. When looking at factors related to postoperative symptomatic spondylolisthesis at the surgical level, preoperative spondylolisthesis, more sagittal orientated facet angles and surgical level (most significantly level L4L5 compared to levels L1L3) showed significant associations. These associations could be used as a basis for devising patient selection criteria, stratifying patients or performing subgroup analyses in future studies regarding decompression surgery with or without fusion.

Rapid Early Progression (REP) of Glioblastoma Is an Independent Negative Prognostic Factor: Results From a Systematic Review and Meta-Analysis

Abstract AIMS In patients with newly-diagnosed glioblastoma, rapid early progression (REP) refers to tumour regrowth between surgery and postoperative chemoradiotherapy. This systematic review and meta-analysis aimed to appraise published data on REP to better characterise and understand this phenomenon. METHOD Systematic searches of MEDLINE, EMBASE and the Cochrane database from inception to 21/10/21. Studies describing the incidence of REP – tumour growth between the postoperative MRI scan and pre-radiotherapy MRI scan in newly-diagnosed glioblastoma, were included. The primary outcome was REP incidence. RESULTS From 1590 search results, 9 studies were included with 716 patients. The median age was 56.9 years (IQR 54.0- 58.8 years). There was a male predominance with a median male-to-female ratio of 1.4 (IQR 1.1-1.5). The median number of days between MRI scans was 34 days (IQR 18-45 days). The mean incidence rate of REP was 45.9% (range 19.3%-72.0%) and significantly lower in studies employing functional imaging to define REP (p&amp;lt;0.001). REP/non-REP groups were comparable with respect to age (p=0.99), gender (p=0.33) and time between scans (p=0.81). REP was associated with shortened overall survival (HR 1.78, 95% CI 1.30-2.43, p&amp;lt;0.001), shortened progression-free survival (HR 1.78, 95% CI 1.30-2.43, p&amp;lt;0.001), subtotal resection (OR 6.96, 95% CI 4-51-10.73, p&amp;lt;0.001) and IDH wildtype versus mutant tumours (OR 0.20, 95% CI 0.02-0.38, p=0.03). MGMT promoter methylation was not associated with REP (OR 1.29, 95% CI 0.72-2.28, p=0.39). CONCLUSION REP occurs in almost half of patients with newly-diagnosed glioblastoma and has a strongly negative prognostic effect. Future studies should investigate its biology and effective treatment strategies.