Magnetic Resonance Imaging Surveillance Research Articles

Automated lung segmentation on chest MRI in children with cystic fibrosis

IntroductionSegmentation of lung structures in medical imaging is crucial for the application of automated post-processing steps on lung diseases like cystic fibrosis (CF). Recently, machine learning methods, particularly neural networks, have demonstrated remarkable improvements, often outperforming conventional segmentation methods. Nonetheless, challenges still remain when attempting to segment various imaging modalities and diseases, especially when the visual characteristics of pathologic findings significantly deviate from healthy tissue.MethodsOur study focuses on imaging of pediatric CF patients [mean age, standard deviation (7.50 ± 4.6)], utilizing deep learning-based methods for automated lung segmentation from chest magnetic resonance imaging (MRI). A total of 165 standardized annual surveillance MRI scans from 84 patients with CF were segmented using the nnU-Net framework. Patient cases represented a range of disease severities and ages. The nnU-Net was trained and evaluated on three MRI sequences (BLADE, VIBE, and HASTE), which are highly relevant for the evaluation of CF induced lung changes. We utilized 40 cases for training per sequence, and tested with 15 cases per sequence, using the Sørensen-Dice-Score, Pearson’s correlation coefficient (r), a segmentation questionnaire, and slice-based analysis.ResultsThe results demonstrated a high level of segmentation performance across all sequences, with only minor differences observed in the mean Dice coefficient: BLADE (0.96 ± 0.05), VIBE (0.96 ± 0.04), and HASTE (0.95 ± 0.05). Additionally, the segmentation quality was consistent across different disease severities, patient ages, and sizes. Manual evaluation identified specific challenges, such as incomplete segmentations near the diaphragm and dorsal regions. Validation on a separate, external dataset of nine toddlers (2–24 months) demonstrated generalizability of the trained model achieving a Dice coefficient of 0.85 ± 0.03.Discussion and conclusionOverall, our study demonstrates the feasibility and effectiveness of using nnU-Net for automated segmentation of lung halves in pediatric CF patients, showing promising directions for advanced image analysis techniques to assist in clinical decision-making and monitoring of CF lung disease progression. Despite these achievements, further improvements are needed to address specific segmentation challenges and enhance generalizability.

EPID-09. THE NATURAL HISTORY AND MOLECULAR ARCHITECTURE OF INCIDENTAL MENINGIOMAS

Abstract The prevalence of asymptomatic, incidental meningiomas is increasing due to greater frequency of brain imaging. This retrospective cohort study of adult patients presenting at a single institution from 1996-2020 integrated clinical data, serial magnetic resonance imaging (MRI) volumetrics, DNA methylation profiling, and targeted gene expression profiling to define the natural history and molecular architecture of incidental meningiomas. Volumetrics were calculated from contrast-enhanced brain MRIs at time of diagnosis compared to serial surveillance MRIs (average 3 MRIs per patient pre-intervention, range: 1-12) DNA methylation groups and gene expression risk scores were defined for 123 samples that underwent resection. Time-to-event analyses were performed for progression-free survival (PFS), symptom-free survival (SFS), and treatment-free survival (TFS). The cohort included 238 meningiomas from 207 patients. Median age at diagnosis was 59 years and 81.5% of patients were female. Median clinical and imaging follow-up were 9.1 and 6.7 years, respectively, during which time 50.8% progressed. Median maximum diameter and volume at diagnosis were 2.20 cm and 4.25 cm3, respectively, and median pre-treatment volumetric growth rate was 19.2% per year. Median pre-treatment PFS and TFS were 3.10 and 1.27 years, respectively, and median SFS and post-treatment PFS were not reached. Cox proportional hazards regression identified maximum diameter at diagnosis as a significant predictor of worse pre-treatment PFS (multivariate HR 1.65 per 1 cm [95% CI 1.19–2.28], p=0.0027) and worse TFS (multivariate HR 1.44 per 1 cm [95% CI 1.17–1.76], p<0.001). Skull base tumors had with worse SFS (multivariate HR 2.48 [95% CI 1.02–6.00], p=0.045). Molecular and histological features among incidental meningiomas that ultimately underwent resection (n=176, 74.0%) were reassuring (89.2% WHO grade 1, 10.2% WHO grade 2). These findings suggest maximum diameter at diagnosis of incidental meningiomas is significantly associated with earlier progression and eventual treatment, and skull base tumors have earlier symptom development.

DNAR-13. LONG TERM FOLLOW-UP OF A LYNCH SYNDROME-ASSOCIATED GLIOBLASTOMA RESISTANT TO STANDARD-OF-CARE CHEMORADIATION

Abstract BACKGROUND Lynch syndrome is caused by pathogenic germline variants in the DNA mismatch repair (MMR) genes, predisposing individuals to malignancies, including glioblastoma (GBM). MMR-deficient tumors are resistant to monofunctional alkylators such as temozolomide but not to bifunctional alkylators such as the nitrosourea lomustine. Anti-programmed cell death protein 1 (PD1) immune checkpoint inhibitor (ICI) pembrolizumab represents another treatment option, which is approved by the United States Food and Drug Administration (FDA) for the treatment of mismatch repair deficient cancers. METHODS We present a patient with multifocal GBM and Lynch syndrome who experienced rapid progression following standard-of-care chemoradiation, followed by durable responses to lomustine and then to pembrolizumab. RESULTS A 58-year-old man with Lynch syndrome (MSH2 mutation) and prior history of colon cancer presented with seizures. Magnetic resonance imaging (MRI) brain identified right frontal and left parietal masses. Right frontal tumor was resected; pathology was consistent with GBM, IDH wildtype, MGMT-unmethylated. Both lesions were treated with radiation therapy (60 Gy, 30 fractions) with concurrent and adjuvant temozolomide. After two cycles of adjuvant temozolomide, his left parietal tumor progressed and was subtotally resected, followed by four cycles of lomustine (stopped due to myelotoxicity). He remained progression-free for 15 months. Surveillance MRI identified new enhancement involving the left frontal lobe, left periventricular white matter, and right internal auditory canal, concerning for leptomeningeal dissemination. MRI spine identified no additional lesions. Cerebrospinal fluid cytology was negative for tumor cells on two occasions. Patient was treated with pembrolizumab. He remains on treatment with stable disease four months after ICI initiation and 31 months after GBM diagnosis. CONCLUSIONS Patients with MMR-deficient GBM resist standard chemoradiation. Alternatives such as nitrosourea or ICI therapy may achieve durable responses. While data is insufficient to administer these agents as upfront therapy in this specific setting, both should be considered as options for recurrent disease.

Safety Profile of Abdominal Magnetic Resonance Imaging (MRI) Performed for Renal Disease Surveillance in Tuberous Sclerosis Complex Patients with Vagus Nerve Stimulation

IntroductionIndividuals with tuberous sclerosis complex (TSC) often present with refractory epilepsy and may be undergoing treatment with vagus nerve stimulation (VNS) to control seizures. Surveillance magnetic resonance imaging (MRI) is necessary to monitor for the renal angiomyolipomas associated with TSC; however, MRI of the abdomen is not approved for patients withVNS therapy. We have many TSC patients with refractory epilelpsy who benefitted from VNS therapy, so we developed an MRI protocol that allows MRI of the abdomen to be performed in these patients to permit safe imaging of their kidneys. Here we report our results using this protocol. MethodsWe performed a retrospective review for all TSC patients seen from 01/01/1997 to 10/01/2022 at a single center to determine VNS implantation status. Patients with VNS implants and abdomen imaging performed according to the protocol for kidney surveillance were included. ResultsSixteen patients with 48 total MRIs of the abdomen were found: 34 (71%) scans were conducted under sedation and 14 (29%) without sedation. None of the patients reported any adverse effects (pain or discomfort). No instances of VNS dysfunction were noted when re-interrogating the device immediately after completion of the imaging studies or at later neurology follow-up appointments. All MRI scans were of good quality for interpretation. ConclusionAbdominal MRIs performed in typical VNS exclusion zones were not associated with adverse events or VNS dysfunction. We believe this protocol is safe and permits the best method for monitoring renal disease in TSC patients with VNS.

8207 Insights From a Case of Insulinoma and Possible Genetic Variants in a Young Woman With Recurrent Hypoglycemia

Abstract Disclosure: M.A. Brandao: None. A. Bharara: None. V.I. Moncada Castro: None. T.C. Tsai: None. Y. Wu: None. S. Marquez Flores: None. K. Divari: None. Introduction: Insulinomas are neuroendocrine neoplasms causing hyperinsulinemic hypoglycemia. They are rare, with a prevalence of 1-4 people per million of the general population. Key features are symptoms of hypoglycemia, low plasma glucose, and symptom relief by correcting hypoglycemia. Here, we report a patient with recurrent hypoglycemia who was found to have insulinoma. Several variants of uncertain significance (VUS) were detected in this patient. This gives us some insights into a broader perspective. Clinical case: A 28-year-old healthy female was found unresponsive by her partner. Blood glucose (BG) was 40 mg/dL when paramedics arrived. She received dextrose and rapidly recovered. She was briefly hospitalized and received glucose infusion with improvement. Subsequently, the patient developed episodes of blurry vision and weakness. She had been eating more frequently to prevent symptoms. Her weight was stable at 65.77 kg. She had not been on any medications. She continued to experience hypoglycemic episodes with BG dropping to 30 mg/dL, so she sought evaluation from an endocrinologist. Laboratory work-up showed Proinsulin of 530.6 pmol/L, C-peptide 5 ng/ml, TSH 1.01 mciu/ml, Beta-hydroxybutyrate (BHOB) 0.7 mg/dL, hemoglobin A1c 4.7%, calcium 8.9 mg/dL, albumin 4.1. Abdominal computed tomography (CT) scan showed an 11 mm nodule anterior to the pancreatic tail. No discrete calcification was noted. Magnetic resonance imaging (MRI) of the abdomen redemonstrated the 10 x 6mm, slightly exophytic lesion in the pancreatic tail. Therefore, she underwent laparoscopic enucleation with pathology showing a 1.7cm well-differentiated grade 2 neuroendocrine tumor, with positive margins. Given its indolent nature, further surgical resection was not recommended. Germline testing showed several VUS: the AXIN2 gene (c.1822C>G), GPC3 gene (c.565G>T), NF2 gene (c.296A>G), RECQL4 gene (c.2791C>G). However, no pathogenic variants were identified. Surveillance MRI of the abdomen six months after the surgery has shown no evidence of recurrent disease. The patient has remained euglycemic and symptoms have not recurred. Conclusion: Insulinomas are typically sporadic but may occur due to an activating T372R mutation in the Yin Yang. It may also occur in the setting of multiple endocrine neoplasia type 1 (MEN-1) syndrome caused by MEN1 gene mutations. Although no pathogenic variant mutations associated with insulinoma were found, several VUS that have not yet been described as related to insulinoma were detected in this patient. Routine genetic testing in newly diagnosed patients is not always recommended. Therefore, further efforts are required to understand genetic mutations and epigenetic modifiers associated with insulinoma. Validation of identified VUS and additional genetic testing in young patients with insulinoma are crucial. Presentation: 6/2/2024

Clinical impact of whole-body MRI in staging and surveillance of patients with myxoid liposarcoma: a 14-year single-centre retrospective study.

To assess the clinical impact of regular whole-body magnetic resonance imaging (WBMRI) surveillance in myxoid liposarcoma patients. This was a retrospective cohort study of myxoid liposarcoma patients who underwent at least one WBMRI at our institution between October 2006 and December 2020. The effect of WBMRI on clinical management, namely treatment modification or additional diagnostic investigations was studied. A standardised WBMRI surveillance protocol was instituted in 2015. We compared patient outcomes for the metastatic patients who had and had not received regular WBMRI surveillance and performed survival analysis for both subgroups. Of the 56 patients (60.7% male, median age: 48.1 years) who underwent 345 WBMRI, 17 (30.3%) had metastases, and 168 WBMRI were performed in this group. The median imaging follow-up for the entire cohort was 35 months; the metastatic group had a median follow-up of 42 months. WBMRI changed the clinical management in 13 (76.5%) metastatic patients, with 33 instances of treatment modification. Thirty-five lesions were labelled 'indeterminate,' 16 (45.7%) had additional investigations/interventions, and 4 (11.4%) were confirmed to be metastatic. Twenty-one metastatic lesions were missed initially on WBMRI and confirmed on subsequent WBMRI, of which 5 (23.8%) were clinically significant. The 5-year survival since the detection of metastasis was better in the regular surveillance subgroup (85.7% vs. 45%), but this was not statistically significant (p = 0.068). Five patients (8.9%) developed their first metastasis more than 5 years after diagnosing the primary lesion. Regular WBMRI surveillance of myxoid liposarcoma patients considerably impacts clinical management by frequently influencing treatment decisions. WBMRI has been recently recommended as an imaging option for the staging and surveillance of myxoid liposarcoma patients. Our study highlights the impact of regular WBMRI surveillance on the clinical management of these patients and how it affects their survival.

Documented Initial Growth Does Not Necessarily Indicate Treatment for Sporadic Vestibular Schwannomas.

To report the natural history of vestibular schwannoma (VS) who elected an initial period of observation and identify prognostic factors. To describe the natural history of growing VS, identify prognostic factors, and review the most recent literature. Prospective cohort study and literature review. Tertiary referral center. Adult patients diagnosed with a VS between January 1998 and February 2023. Magnetic resonance imaging surveillance. Growth-free survival and subsequent growth-free survival considering significant growth as a change in size of ≥2 mm. Of 430 patients undergoing observation with serial magnetic resonance imaging, 193 (44.9%) demonstrated significant growth at a median of 1.6 years (interquartile range, 0.94-3.51). Of the 193 patients who presented an initial episode of growth, 137 elected to continue to be observed. Of those, 83 (60.6%) presented a second episode of growth at a median of 1.43 years (interquartile range, 1.00-2.49). The subsequent growth-free survival rates (95% confidence interval) at 1, 3, 5, 7, and 10 years were 91.79% (87.26-96.56%), 64.44% (56.56-73.42%), 52.52% (44.23-62.35%), 42.23% (33.92-52.56%), and 36.11% (27.89-46.76%), respectively. Univariate and multivariate Cox regression analyses showed that EC tumor location and initial growth rate were significant predictors of subsequent growth. Close observation after documentation of growth is an appropriate management in well-selected cases given that only around 56% of the tumor will continue to grow. Extracanalicular tumor location and initial growth rate are promising prognostic factors to help determine which patient would be a better candidate for close surveillance after initial documentation of growth.

Effects of brain radiotherapy strategies on survival in the era of MRI for patients with limited stage small cell lung cancer

Background and purposeIn the context of the widespread availability of magnetic resonance imaging (MRI) and aggressive salvage irradiation techniques, there has been controversy surrounding the use of prophylactic cranial irradiation (PCI) for small-cell lung cancer (SCLC) patients. This study aimed to explore whether regular brain MRI plus salvage brain irradiation (SBI) is not inferior to PCI in patients with limited-stage SCLC (LS-SCLC).MethodsThis real-world multicenter study, which was conducted between January 2014 and September 2020 at three general hospitals, involved patients with LS-SCLC who had a good response to initial chemoradiotherapy and no brain metastasis confirmed by MRI. Overall survival (OS) was compared between patients who did not receive PCI for various reasons but chose regular MRI surveillance and followed salvage brain irradiation (SBI) when brain metastasis was detected and patients who received PCI.Results120 patients met the inclusion criteria. 55 patients received regular brain MRI plus SBI (SBI group) and 65 patients received PCI (PCI group). There was no statistically significant difference in median OS between the two groups (27.14 versus 33.00 months; P = 0.18). In the SBI group, 32 patients underwent whole brain radiotherapy and 23 patients underwent whole brain radiotherapy + simultaneous integrated boost. On multivariate analysis, only extracranial metastasis was independently associated with poor OS in the SBI group.ConclusionThe results of this real-world study showed that MRI surveillance plus SBI is not inferior to PCI in OS for LS-SCLC patients who had a good response to initial chemoradiotherapy.

Beyond Clinical Examination: Utilizing MRI Surveillance to Detect Recurrence of Soft Tissue Sarcomas and Differentiate from Posttherapeutic Changes.

Early detection of soft tissue sarcoma (STS) recurrence is essential; however, the role and timeline of Magnetic resonance imaging (MRI) surveillance are still under debate. The aim of this study was to determine whether local recurrence (LR) could be identified via clinical examination alone and to assess the MRI morphology of primary STS and LR. This retrospective study included all patients with STS recurrence after surveillance for at least five years from the tumor database of the Medical University of Vienna from 2000 until December 2023. The characteristics of primary STS and LR and the time interval to recurrence and clinical detectability were assessed. The MRIs of LR and posttherapeutic changes (PTC) were compared with the initial MRIs. A total of 57 patients (60% male; mean age 58.5 ± 18.0 years) with STS and histologically confirmed LR were included. The mean time interval to LR was 2.3 ± 1.8 years (range 108 to 3037 days). The clinically detectable recurrences were significantly larger than the inapparent ones (71.9 cm3 vs. 7.0 cm3; p < 0.01). The MRI morphology of all LRs (26/26) closely resembled the initial STS. For comparison, nine patients were included with clinically suspected LRs, which were histologically proven to be PTC. None of these resembled the primary STS. Based on clinical symptoms alone, especially small and early recurrences can be missed, which supports the importance of MRI surveillance.

Impact of microscopic deposits of yolk sac tumor on recurrence of mature sacrococcygeal teratoma.

Sacrococcygeal teratomas (SCT) with malignant histology frequently recur and are treated aggressively, but risk factors and surveillance protocols are less established for mature tumors. In particular, prior studies have not investigated whether microscopic deposits of yolk sac tumor (YST) in otherwise mature teratomas lead to higher recurrence rates. We reviewed patients with mature SCTs resected at our institution from 2011 to 2021 and analyzed tumor characteristics, treatment, and outcomes. We identified 56 patients with mature SCT, of which 9 (16%) demonstrated microscopic YST. Following surgery, 7/56 (13%) patients developed local recurrence at a mean of 1.2 ± 0.7 years, while no patients developed metastases. Recurrence was more likely in patients with microscopic YST [5/9 (56%) vs. 2/47 (4%), p = 0.021] and positive margins [6/24 (35%) vs. 1/32 (3.1%), p = 0.030]. A solid tumor component tended to increase recurrence risk as well [6/29 (21%) vs. 1/27 (4%), p = 0.053]. Five patients demonstrated malignant recurrence and were all detected by a rising alpha-fetoprotein (AFP), while two patients demonstrated recurrence of mature teratoma and were detected on surveillance magnetic resonance imaging (MRI). Microscopic foci of YST may increase recurrence risk for patients with mature SCT. Such patients might benefit from closer postoperative surveillance with serial AFP measurements and MRI.

Surveillance Strategies After Primary Treatment for Patients with Invasive Lobular Carcinoma of the Breast: Method of Local Recurrence Detection After Breast-Conserving Surgery

BackgroundInvasive lobular carcinoma (ILC) is the second most common subtype of breast cancer. Although mammography is known to have low sensitivity for ILC, there are no data to guide the optimal surveillance after treatment. We explored surveillance strategies after breast-conserving surgery (BCS) for ILC and determined the proportion of imaging-detected recurrences versus interval cancers.MethodsFrom an institutional database of 813 women, we retrospectively identified patients who underwent BCS for stage I–III ILC and subsequently had a recurrence. We categorized patients by surveillance strategy and determined the modality of recurrence detection. Interval cancer rates for local recurrences were compared across surveillance strategies using the Chi-square test. We evaluated overall survival with the log-rank test and a Cox proportional hazards model.ResultsWe included 58 patients with ILC who had a recurrence after BCS. Of these, 22 (37.9%) had local recurrence, 27 (46.6%) had distant recurrence, and 9 (15.5%) had both local and distant recurrence. Most patients underwent routine mammographic surveillance (65.2%), with 19.6% having supplemental breast magnetic resonance imaging (MRI) and 15.2% having no surveillance. The interval cancer rate was significantly higher in the mammographic surveillance group compared with the MRI surveillance group (61.9% vs. 16.7%; p < 0.001).ConclusionIn this study of patients with recurrence after BCS for primary treatment of stage I–III ILC, we found that most local recurrences were not detected by surveillance mammography. These data support further investigation of supplemental imaging beyond mammography specifically for patients with ILC who undergo BCS.

MRI for hepatocellular carcinoma and the role of abbreviated MRI for surveillance of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) constitutes the majority of liver cancers and significantly impacts global cancer mortality. While ultrasound (US) with or without alpha-fetoprotein is the mainstay for HCC surveillance, its limitations highlight the necessity for more effective surveillance tools. Therefore, this review explores evolving imaging modalities and abbreviated magnetic resonance imaging (MRI) (AMRI) protocols as promising alternatives, addressing challenges in HCC surveillance. This comprehensive review delves into the evaluation and challenges of HCC surveillance tools, focusing on non-contrast abbreviated MRI (NC-AMRI) and contrast-enhanced abbreviated MRI protocols. It covers the implementation of AMRI for HCC surveillance, patient preferences, adherence, and strategies for optimizing cost-effectiveness. Additionally, the article provides insights into prospects for HCC surveillance by summarizing meta-analyses, prospective studies, and ongoing clinical trials evaluating AMRI protocols. The opinions underscore the transformative impact of AMRI on HCC surveillance, especially in overcoming US limitations. Promising results from NC-AMRI protocols indicate its potential for high-risk patient surveillance, though prospective studies in true surveillance settings are essential for validation. Future research should prioritize risk-stratified AMRI protocols and address cost-effectiveness for broader clinical implementation, alongside comparative analyses with US for optimal surveillance strategies.

CP-06. PEDIATRIC CRANIOPHARYNGIOMA: SINGLE CENTER RETROSPECTIVE STUDY OF SURVIVAL, ENDOCRINOLOGIC, AND VISION OUTCOMES IN 90 PATIENTS

Abstract BACKGROUND Craniopharyngioma is histologically benign. However, due to its location, morbidity is high and may be impacted by therapeutic approach. METHODS A retrospective study of patients treated for craniopharyngioma at Seattle Children’s Hospital from 1996-2023 was performed. Surgical approach, extent of resection, subsequent surgery, radiation and medical therapies, and serial surveillance magnetic resonance imaging for progression were reviewed. Five-year overall survival (OS) and progression free survival (PFS) were calculated and morbidity including endocrine and vision dysfunction was described. RESULTS 90 patients were included of which 53(58.9%) were male. Median age at diagnosis was 8.70 (range 1.39-25.17) years. Surgical approach included endoscopic (N=24), craniotomy (N=64), and combined (N=2). Extent of resection was biopsy N=2, subtotal resection N=7, near total resection N=38, gross total resection N=30. Pathology was adamantinomatous subtype in all cases and 68 had a documented CTNNB1 alteration and 3 had a BRAF alteration in those with molecular analysis. 5-year OS was 96.1% (SE 0.13) and 5-year PFS was 51.9% (SE0.21), with median follow-up of 97 months. Transcranial compared to endoscopic endonasal approach was associated with increased risk of progression (62% vs 30%, OR 1.23). 34 patients were treated with radiation upfront (N=19) or at progression (N=15). 55% of patients at diagnosis and an additional 30% in follow up had pituitary hormone dysfunction. Hypothalamic obesity was documented in 31% of patients and varied by surgical approach. At presentation, ophthalmologic abnormalities included optic nerve edema (18%) and optic nerve pallor (24%) and 30% had abnormal visual acuity. Following initial surgery, 50% had improvement in visual acuity, 35% stable and 15% had worsened visual acuity. CONCLUSIONS Upfront surgical strategy may impact risk of disease recurrence; however, its relationship to long term morbidity is not clear. Further work to delineate therapeutic strategies and their relationship to morbidity in this patient population is needed.

QOL-06. RECURRENCE PATTERNS AND SURVEILLANCE IMAGING IN PEDIATRIC BRAIN TUMOR SURVIVORS

Abstract BACKGROUND Surveillance magnetic resonance imaging (MRI) is routinely used to detect recurrence in pediatric central nervous system (CNS) tumors. Frequency of neuroimaging varies with no standardized approach. METHODS A single institution retrospective cohort study evaluated frequency and pattern of recurrences. Pediatric patients (birth to age 21 years) diagnosed with a primary CNS tumor between 1988 and 2011 treated at Lurie Children’s Hospital were included. RESULTS This study included 476 patients; the majority diagnosed with a low-grade glioma (LGG) (n=138; 29%), high grade glioma (HGG) (n=77; 16%), ependymoma (n=70; 15%) or medulloblastoma (n=61; 13%). LGG, HGG and ependymoma patients more commonly had multiply recurrent disease (p=0.08), with ependymoma patients demonstrating ≥2 relapses in 47% of cases. Recurrent disease was identified by imaging more often than clinical symptoms (65% vs 32%; p=&amp;lt;0.01). Treatment at relapse included surgical managment more often than non-surgical approach (59% vs. 41%; p=0.0016) in patients, leading to pathology confirmation of recurrence. Mean time to first relapse for the entire cohort was 2.5 years (range 1 day-24.8 years). Patients diagnosed with meningioma demonstrated the longest mean time to first relapse (74.7 months) whereas those with Atypical Teratoid Rhabdoid Tumor and Choroid plexus carcinoma tended to have the shortest time to relapse (8.9 months and 9 months, respectively). Overall, 22 patients sustained first relapse &amp;gt;10 years from initial diagnosis, including those diagnosed with LGG, medulloblastoma, pineoblastoma, craniopharyngioma, GCT, and meningioma. CONCLUSION With a higher percentage of tumor recurrence/progression seen on neuroimaging before development of symptoms, surveillance imaging is necessary in routine follow up of pediatric CNS tumor survivors. While the study is limited since we did not look at overall survival, earlier detection of recurrence would lead to earlier initiation of treatment and implementation of salvage treatment regimens which can impact survival and quality of life.

Regression of all untreated lesions in multifocal low-grade meningioma following fractionated stereotactic radiotherapy-abscopal effect or spontaneous regression? : Case report and review of the literature.

Abscopal effects have been reported predominantly in metastatic cancers, indicating aradiographic response in alesion that has not been included in the radiotherapy target volume. The response is interpreted as ahumoral immune response to radiotherapy-generated tumour-specific antigens. In this case study, we present the first histologically confirmed multifocal low-grade meningioma with spontaneous regression of all other lesions after conventionally fractionated stereotactic radiotherapy (RT). Two localisations, right frontal and right spheno-orbital, were resected at the time of the initial diagnosis in a66-year-old woman. RT was performed 1year later to aprogressive occipital lesion at the cerebral falx. Regular magnetic resonance imaging (MRI) showed slightly decreasing tumour volume in untreated lesions 1year after RT and continued during further follow-up. Up to > 7years after treatment, MRI demonstrated an almost complete response of all initial lesions. Two prior reports withmeningioma were published in onepatient with an atypical meningioma after conventionally fractionated RT and anotherpatient with an intracranial meningiomatosis after radiosurgery. This case study supports the concepts of treating only progressive or symptomatic meningioma lesions locally and careful regular MRI surveillance for further assessment. Potential active interventions to trigger an abscopal effect are currently not known. Further research of this beneficial effect for our patients should be supported.

Comparison of non-contrast abbreviated MRI and ultrasound as surveillance modalities for HCC

Ultrasound (US) is recommended for HCC surveillance in high-risk patients but has limited performance in detecting early-stage HCC. We aimed to compare the diagnostic performance of biannual US and annual non-contrast abbreviated magnetic resonance imaging (NC-AMRI) as HCC surveillance modalities in high-risk patients. This prospective, multicenter cohort study enrolled participants with an estimated annual risk of HCC greater than 5% between October 2015 and April 2017. Participants underwent six rounds of HCC surveillance at 6-month intervals, with both US and NC-AMRI at rounds 1, 3, and 5, and only US at rounds 2, 4, and 6. The sensitivity, diagnostic yield (DY), and false referral rate (FRR) for HCC detection by US and NC-AMRI were compared. In total, 208 participants underwent 980 US and 516 NC-AMRI examinations during 30 months of follow-up. Among them, 34 HCCs were diagnosed in 31 participants, with 20 (64.5%) classified as very early-stage and 11 (35.5%) as early-stage HCC. The sensitivity of annual NC-AMRI (71.0%, 22/31) was marginally higher than that of biannual US (45.2%, 14/31; p= 0.077). NC-AMRI showed a significantly higher DY than US (4.26% vs. 1.43%, p <0.001), with a similar FRR (2.91% vs. 3.06%, p= 0.885). A simulation of alternating US and NC-AMRI at 6-month intervals yielded a sensitivity of 83.9% (26/31), significantly exceeding that of biannual US (p= 0.006). Annual NC-AMRI showed a marginally higher sensitivity than biannual US for HCC detection in high-risk patients. The DY of annual NC-AMRI was significantly higher than that of biannual US, without increasing the FRR. Thus, alternating US and NC-AMRI at 6-month intervals could be an optimal surveillance strategy for high-risk patients. Current guidelines permit the use of magnetic resonance imaging (MRI) as a surveillance tool for hepatocellular carcinoma in patients in whom ultrasonography (US) is inadequate. However, the specific indications, imaging sequences, and intervals for MRI surveillance remain unclear. In our study, we found that annual non-contrast abbreviated MRI exhibited marginally higher sensitivity and significantly better diagnostic yield than biannual US in patients at high risk of hepatocellular carcinoma. Alternating US and non-contrast abbreviated MRI at 6-month intervals led to significantly improved sensitivity compared to biannual US, making it a potentially optimal surveillance strategy for high-risk patients. NCT02551250.

Hip Preservation and Capanna Reconstruction for Pediatric Proximal Femur Ewing Sarcoma: A Report of 2 Cases.

This is a first report describing preservation of the femoral head by transcervical resection of proximal femoral Ewing sarcoma in 2 pediatric patients. A unique Capanna reconstruction supported joint salvage. At 1 year, Pediatric Outcomes Data Collection Instrument and Pediatric Toronto Extremity Salvage Score outcomes were excellent. Surveillance magnetic resonance imaging was without evidence of recurrence or impaired perfusion to the femoral head. We demonstrate the feasibility of hip joint preservation and maintenance of femoral head viability after transcervical resection of pediatric proximal femur bone sarcomas while preserving the medial circumflex femoral artery. This technique may be a preferred option over joint sacrifice and endoprosthetic replacement in young patients when tumor margins permit.

Recurrence Patterns and Surveillance Imaging in Pediatric Brain Tumor Survivors.

Surveillance magnetic resonance imaging (MRI) is routinely used to detect recurrence in pediatric central nervous system (CNS) tumors. The frequency of neuroimaging surveillance varies without a standardized approach. A single-institutional retrospective cohort study evaluated the frequency of recurrences. This study included 476 patients with the majority diagnosed with low-grade glioma (LGG) (n=138, 29%), high-grade glioma (HGG) (n=77, 16%), ependymoma (n=70, 15%), or medulloblastoma (n=61, 13%). LGG, HGG, and ependymoma patients more commonly had multiply recurrent disease ( P =0.08), with ependymoma patients demonstrating ≥2 relapses in 47% of cases. Recurrent disease was identified by imaging more often than clinical symptoms (65% vs. 32%; P =<0.01). Patients diagnosed with meningioma demonstrated the longest mean time to first relapse (74.7mo) whereas those with atypical teratoid rhabdoid tumor and choroid plexus carcinoma tended to have the shortest time to relapse (8.9and 9mo, respectively). Overall, 22 patients sustained first relapse >10 years from initial diagnosis. With a higher tendency toward detection of tumor recurrence/progression on MRI surveillance in comparison to clinical progression, surveillance imaging is necessary in routine follow up of pediatric CNS tumor survivors. With some relapses >10 years from initial diagnosis, imaging beyond this time point may be useful in particular tumor types. While the study is limited in outcome analysis, earlier detection of recurrence would lead to earlier initiation of treatment and implementation of salvage treatment regimens which can impact survival and quality of life.

210P Prophylactic cranial irradiation (PCI) in patients with limited-stage small cell lung cancer (LS-SCLC) in the era of magnetic resonance imaging surveillance: A systematic review and meta-analysis

210P Prophylactic cranial irradiation (PCI) in patients with limited-stage small cell lung cancer (LS-SCLC) in the era of magnetic resonance imaging surveillance: A systematic review and meta-analysis

MRI Surveillance and Breast Cancer Mortality in Women With BRCA1 and BRCA2 Sequence Variations

Magnetic resonance imaging (MRI) surveillance is offered to women with a pathogenic variant in the BRCA1 or BRCA2 gene who face a high lifetime risk of breast cancer. Surveillance with MRI is effective in downstaging breast cancers, but the association of MRI surveillance with mortality risk has not been well defined. To compare breast cancer mortality rates in women with a BRCA1 or BRCA2 sequence variation who entered an MRI surveillance program with those who did not. Women with a BRCA1 or BRCA2 sequence variation were identified from 59 participating centers in 11 countries. Participants completed a baseline questionnaire between 1995 and 2015 and a follow-up questionnaire every 2 years to document screening histories, incident cancers, and vital status. Women who had breast cancer, a screening MRI examination, or bilateral mastectomy prior to enrollment were excluded. Participants were followed up from age 30 years (or the date of the baseline questionnaire, whichever was later) until age 75 years, the last follow-up, or death from breast cancer. Data were analyzed from January 1 to July 31, 2023. Entrance into an MRI surveillance program. Cox proportional hazards modeling was used to estimate the hazard ratios (HRs) and 95% CIs for breast cancer mortality associated with MRI surveillance compared with no MRI surveillance using a time-dependent analysis. A total of 2488 women (mean [range] age at study entry 41.2 [30-69] years), with a sequence variation in the BRCA1 (n = 2004) or BRCA2 (n = 484) genes were included in the analysis. Of these participants, 1756 (70.6%) had at least 1 screening MRI examination and 732 women (29.4%) did not. After a mean follow-up of 9.2 years, 344 women (13.8%) developed breast cancer and 35 women (1.4%) died of breast cancer. The age-adjusted HRs for breast cancer mortality associated with entering an MRI surveillance program were 0.20 (95% CI, 0.10-0.43; P < .001) for women with BRCA1 sequence variations and 0.87 (95% CI, 0.10-17.25; P = .93) for women with BRCA2 sequence variations. Results of this cohort study suggest that among women with a BRCA1 sequence variation, MRI surveillance was associated with a significant reduction in breast cancer mortality compared with no MRI surveillance. Further studies of women with BRCA2 sequence variations are needed to ascertain these women obtain the same benefits associated with MRI surveillance.