Preoperative Metastatic Brain Tumor-Associated Intracerebral Hemorrhage Is Associated With Dismal Prognosis

Improving differentiation of hemorrhagic brain metastases from non-neoplastic hematomas using radiomics and clinical feature fusion

OBJECTIVES

This study aimed to develop and validate a fusion model combining multi-sequence MRI radiomics and clinico-radiological features to distinguish hemorrhagic brain metastasis covered by hematoma (HBM.cbh) from non-neoplastic intracranial hematomas (nn-ICH).

METHODS

The data of 146 patients with pathologically or clinically proven HBM.cbh (n = 55) and nn-ICH (n = 91) were collected from two clinical institutions. Radiomics features were extracted from various regions (hemorrhage and/or edema) based on T2-weighted, T1-weighted, fluid-attenuated inversion-recovery, and T1 contrast-enhanced imaging. Synthetic minority over-sampling technique (SMOTE) was performed to balance the minority group (HBM.cbh). Logistic regression (LR) and k-nearest neighbors (KNN) were utilized to construct the models based on clinico-radiological factors (clinical model), radiomic features from various modalities of MRI (radiomics model), and their combination (fusion model). The area under the curve (AUC) values of different models on the external dataset were compared using DeLong's test.

RESULTS

The 4-sequence radiomics model based on the entire region performed the best in all radiomics models, with or without SMOTE, where the AUCs were 0.83 and 0.84, respectively. The AUC of clinical mode was 0.71 with SMOTE, and 0.62 without SMOTE. The fusion model demonstrated excellent predictive value with or without SMOTE (AUC: 0.93 and 0.90, respectively), outperforming both the radiomics and clinical model (0.93 vs. 0.83, 0.71, p < 0.05 and 0.90 vs. 0.84, 0.62, p < 0.05, respectively).

CONCLUSIONS

The multi-sequence radiomics model is an effective method for differentiating HBM.cbh from nn-ICH. It can yield the best diagnostic performance prediction model when combined with clinico-radiological features.

Transient and permanent hydrocephalus following resection of brain metastases located in the posterior fossa: incidence, risk factors and the necessity of perioperative external ventricular drainage placement

PURPOSE

Prophylactic insertion of an external ventricular drainage (EVD) prior to the resection of posterior fossa metastases (PFMs) is a common approach to address postoperative transient and permanent hydrocephalus. However, predicting surgery-related hydrocephalus in the preoperative phase continues to be a challenge. This study aims to analyze the incidence, preoperatively collectable risk factors and necessity of perioperative external ventricular drainage placement after posterior fossa metastasis surgery.

METHODS

All patients undergoing surgery for PFMs at the authors' neuro-oncological center between 2015 and 2021 were identified and assessed for postoperative hydrocephalus occurrence. Tumour volume, edema volume, and 4th ventricle volume were assessed on preoperative magnetic resonance imaging scans using the IntelliSpace Portal 5.0. A multivariable logistic regression analysis was performed to identify possible predictors for postoperative hydrocephalus occurrence.

RESULTS

Postoperative hydrocephalus occurred in 14 of the 130 identified PFM patients (11%). Multivariable analysis and receiver operating characteristic (ROC) analysis revealed a 4th -ventricle-to-tumor-volume ratio ≤ 0.02 (OR 33.1, 95% CI 3.8-284.3, p = 0.001), an edema-to- tumor-volume ratio ≤ 0.85 (OR 10.6, 95% CI 2.4-47.4, p = 0.002), an imaging-morphological contact to the 4th ventricle (OR 5, 95% CI 1.4-18, p = 0.013), and multiple intracranial metastases (OR 2.4, 95% CI 1-5.9, p = 0.045) as independent predictors for surgery-related postoperative hydrocephalus occurrence.

CONCLUSION

The present study identifies preoperatively detectable risk factors for the occurrence of postoperative hydrocephalus following surgery for PFMs. These findings may provide guidance in clinical decision-making regarding prophylactic EVD placement.

Clinical and imaging manifestations of intracerebral hemorrhage in brain tumors and metastatic lesions: a comprehensive overview

PURPOSE

This observational study aims to provide a detailed clinical and imaging characterization/workup of acute intracerebral hemorrhage (ICH) due to either an underlying metastasis (mICH) or brain tumor (tICH) lesion.

METHODS

We conducted a retrospective, single-center study, evaluating patients presenting with occult ICH on initial CT imaging, classified as tICH or mICH on follow-up MRI imaging according to the H-Atomic classification. Demographic, clinical and radiological data were reviewed.

RESULTS

We included 116 patients (tICH: 20/116, 17.24%; mICH: 96/116, 82.76%). The most common malignancies causing ICH were lung cancer (27.59%), malignant melanoma (18.10%) and glioblastoma (10.34%). The three most common stroke-like symptoms observed were focal deficit (62/116, 53.45%), dizziness (42/116, 36.21%) and cognitive impairment (27/116, 23.28%). Highest mICH prevalence was seen in the occipital lobe (mICH: 28.13%, tICH: 0.00%; p = 0.004) with tICH more in the corpus callosum (tICH: 10.00%, mICH: 0.00%; p = 0.029). Anticoagulation therapy was only frequent in mICH patients (tICH: 0.00%, mICH: 5.21%; p = 0.586). Hemorrhage (tICH: 12682 mm3, mICH: 5708 mm3, p = 0.020) and edema volumes (tICH: 49389 mm3, mICH: 20972 mm3, p = 0.035) were significantly larger within tICH patients.

CONCLUSION

More than half of the patients with neoplastic ICH exhibited stroke-like symptoms. Lung cancer was most common in mICH, glioblastoma in tICH. While clinical presentations were similar, significant differences in tumor location and treatments were discernible.

In vivo characterization of brain tumor biomechanics: magnetic resonance elastography in intracranial B16 melanoma and GL261 glioma mouse models

Introduction

Magnetic Resonance Elastography (MRE) allows the non-invasive quantification of tumor biomechanical properties in vivo. With increasing incidence of brain metastases, there is a notable absence of appropriate preclinical models to investigate their biomechanical characteristics. Therefore, the purpose of this work was to assess the biomechanical characteristics of B16 melanoma brain metastases (MBM) and compare it to murine GL261 glioblastoma (GBM) model using multifrequency MRE with tomoelastography post processing.

Methods

Intracranial B16 MBM (n = 6) and GL261 GBM (n = 7) mouse models were used. Magnetic Resonance Imaging (MRI) was performed at set intervals after tumor implantation: 5, 7, 12, 14 days for MBM and 13 and 22 days for GBM. The investigations were performed using a 7T preclinical MRI with 20 mm head coil. The protocol consisted of single-shot spin echo-planar multifrequency MRE with tomoelastography post processing, contrast-enhanced T1- and T2-weighted imaging and diffusion-weighted imaging (DWI) with quantification of apparent diffusion coefficient of water (ADC). Elastography quantified shear wave speed (SWS), magnitude of complex MR signal (T2/T2*) and loss angle (φ). Immunohistological investigations were performed to assess vascularization, blood-brain-barrier integrity and extent of glucosaminoglucan coverage.

Results

Volumetric analyses displayed rapid growth of both tumor entities and softer tissue properties than healthy brain (healthy: 5.17 ± 0.48, MBM: 3.83 ± 0.55, GBM: 3.7 ± 0.23, [m/s]). SWS of MBM remained unchanged throughout tumor progression with decreased T2/T2* intensity and increased ADC on days 12 and 14 (p<0.0001 for both). Conversely, GBM presented reduced φ values on day 22 (p=0.0237), with no significant alterations in ADC. Histological analysis revealed substantial vascularization and elevated glycosaminoglycan content in both tumor types compared to healthy contralateral brain.

Discussion

Our results indicate that while both, MBM and GBM, exhibited softer properties compared to healthy brain, imaging and histological analysis revealed different underlying microstructural causes: hemorrhages in MBM and increased vascularization and glycosaminoglycan content in GBM, further corroborated by DWI and T2/T2* contrast. These findings underscore the complementary nature of MRE and its potential to enhance our understanding of tumor characteristics when used alongside established techniques. This comprehensive approach could lead to improved clinical outcomes and a deeper understanding of brain tumor pathophysiology.

Predictors and surgical outcome of hemorrhagic metastatic brain malignancies

PURPOSE

Intracerebral metastases present a substantial risk of tumor-associated intracerebral hemorrhage (ICH). This study aimed to investigate the risk of hemorrhagic events in brain metastases (BM) from various primary tumor sites and evaluate the safety and outcomes of surgical tumor removal.

METHODS

A retrospective, single-center review of medical records was conducted for patients who underwent BM removal between January 2016 and December 2017. Patients with hemorrhagic BM were compared to those with non-hemorrhagic BM. Data on preoperative predictors, perioperative management, and postoperative outcomes were collected and analyzed.

RESULTS

A total of 229 patients met the inclusion criteria. Melanoma metastases were significantly associated with preoperative hemorrhage, even after adjusting for confounding factors (p = 0.001). Poor clinical status (p = 0.001), larger tumor volume (p = 0.020), and unfavorable prognosis (p = 0.001) independently predicted spontaneous hemorrhage. Importantly, preoperative use of anticoagulant medications was not linked to increased hemorrhagic risk (p = 0.592). Surgical removal of hemorrhagic BM, following cessation of blood-thinning medication, did not significantly affect intraoperative blood loss, surgical duration, or postoperative rebleeding risk (p > 0.096). However, intra-tumoral hemorrhage was associated with reduced overall survival (p = 0.001).

CONCLUSION

This study emphasizes the safety of anticoagulation in patients with BM and highlights the safety of neurosurgical treatment in patients with hemorrhagic BM when blood-thinning medication is temporarily paused. The presence of intra-tumoral hemorrhage negatively impacts survival, highlighting its prognostic significance in BM patients. Further research with larger cohorts is warranted to validate these findings and elucidate underlying mechanisms.

An MRI radiomics approach to discriminate haemorrhage-prone intracranial tumours before stereotactic biopsy

PURPOSE

To explore imaging biomarkers predictive of intratumoral haemorrhage for lesions intended for elective stereotactic biopsy.

METHOD

This study included a retrospective cohort of 143 patients with 175 intracranial lesions intended for stereotactic biopsy. All the lesions were randomly split into a training dataset ( n =121) and a test dataset ( n =54) at a ratio of 7:3. Thirty-four lesions were defined as "hemorrhage-prone tumors" as haemorrhage occurred between initial diagnostic MRI acquisition and the scheduled biopsy procedure. Radiomics features were extracted from the contrast-enhanced T1 Weighted Imaging and T2 Weighted Imaging images. Features informative of haemorrhage were then selected by the LASSO algorithm, and an Support Vector Machine model was built with selected features. The Support Vector Machine model was further simplified by discarding features with low importance and calculating them using a "permutation importance" method. The model's performance was evaluated with confusion matrix-derived metrics and area under curve (AUC) values on the independent test dataset.

RESULTS

Nine radiomics features were selected as haemorrhage-related features of intracranial tumours by the LASSO algorithm. The simplified model's sensitivity, specificity, accuracy, and AUC reached 0.909, 0.930, 0.926, and 0.949 (95% CI: 0.865-1.000) on the test dataset in the discrimination of "hemorrhage-prone tumors". The permutation method rated feature "T2_gradient_firstorder_10Percentile" as the most important, the absence of which decreased the model's accuracy by 10.9%.

CONCLUSION

Radiomics features extracted on contrast-enhanced T1 Weighted Imaging and T2 Weighted Imaging sequences were predictive of future haemorrhage of intracranial tumours with favourable accuracy. This model may assist in the arrangement of biopsy procedures and the selection of target lesions in patients with multiple lesions.

The molecular signature and prognosis of glioma with preoperative intratumoral hemorrhage: a retrospective cohort analysis

BACKGROUND

Intratumoral hemorrhage, though less common, could be the first clinical manifestation of glioma and is detectable via MRI; however, its exact impacts on patient outcomes remain unclear and controversial. The 2021 WHO CNS 5 classification emphasised genetic and molecular features, initiating the necessity to establish the correlation between hemorrhage and molecular alterations. This study aims to determine the prevalence of intratumoral hemorrhage in glioma subtypes and identify associated molecular and clinical characteristics to improve patient management.

METHODS

Integrated clinical data and imaging studies of patients who underwent surgery at the Department of Neurosurgery at Peking Union Medical College Hospital from January 2011 to January 2022 with pathological confirmation of glioma were retrospectively reviewed. Patients were divided into hemorrhage and non-hemorrhage groups based on preoperative magnetic resonance imaging. A comparison and survival analysis were conducted with the two groups. In terms of subgroup analysis, we classified patients into astrocytoma, IDH-mutant; oligodendroglioma, IDH-mutant, 1p/19q-codeleted; glioblastoma, IDH-wildtype; pediatric-type gliomas; or circumscribed glioma using integrated histological and molecular characteristics, according to WHO CNS 5 classifications.

RESULTS

457 patients were enrolled in the analysis, including 67 (14.7%) patients with intratumoral hemorrhage. The hemorrhage group was significantly older and had worse preoperative Karnofsky performance scores. The hemorrhage group had a higher occurrence of neurological impairment and a higher Ki-67 index. Molecular analysis indicated that CDKN2B, KMT5B, and PIK3CA alteration occurred more in the hemorrhage group (CDKN2B, 84.4% vs. 62.2%, p = 0.029; KMT5B, 25.0% vs. 8.9%, p = 0.029; and PIK3CA, 81.3% vs. 58.5%, p = 0.029). Survival analysis showed significantly worse prognoses for the hemorrhage group (hemorrhage 18.4 months vs. non-hemorrhage 39.1 months, p = 0.01). In subgroup analysis, the multivariate analysis showed that intra-tumoral hemorrhage is an independent risk factor only in glioblastoma, IDH-wildtype (162 cases of 457 overall, HR = 1.72, p = 0.026), but not in other types of gliomas. The molecular alteration of CDK6 (hemorrhage group p = 0.004, non-hemorrhage group p < 0.001), EGFR (hemorrhage group p = 0.003, non-hemorrhage group p = 0.001), and FGFR2 (hemorrhage group p = 0.007, non-hemorrhage group p = 0.001) was associated with shorter overall survival time in both hemorrhage and non-hemorrhage groups.

CONCLUSIONS

Glioma patients with preoperative intratumoral hemorrhage had unfavorable prognoses compared to their nonhemorrhage counterparts. CDKN2B, KMT5B, and PIK3CA alterations were associated with an increased occurrence of intratumoral hemorrhage, which might be future targets for further investigation of intratumoral hemorrhage.

Neuro-oncologic Emergencies

OBJECTIVE

Neuro-oncologic emergencies have become more frequent as cancer remains one of the leading causes of death in the United States, second only to heart disease. This article highlights key aspects of epidemiology, diagnosis, and management of acute neurologic complications in primary central nervous system malignancies and systemic cancer, following three thematic classifications: (1) complications that are anatomically or intrinsically tumor-related, (2) complications that are tumor-mediated, and (3) complications that are treatment-related.

LATEST DEVELOPMENTS

The main driver of mortality in patients with brain metastasis is systemic disease progression; however, intracranial hypertension, treatment-resistant seizures, and overall decline due to increased intracranial burden of disease are the main factors underlying neurologic-related deaths. Advances in the understanding of tumor-specific characteristics can better inform risk stratification of neurologic complications. Following standardized grading and management algorithms for neurotoxic syndromes related to newer immunologic therapies is paramount to achieving favorable outcomes.

ESSENTIAL POINTS

Neuro-oncologic emergencies span the boundaries of subspecialties in neurology and require a broad understanding of neuroimmunology, neuronal hyperexcitability, CSF flow dynamics, intracranial compliance, and neuroanatomy.

Unlocking molecular mechanisms and identifying druggable targets in matched-paired brain metastasis of breast and lung cancers

Introduction

The incidence of brain metastases in cancer patients is increasing, with lung and breast cancer being the most common sources. Despite advancements in targeted therapies, the prognosis remains poor, highlighting the importance to investigate the underlying mechanisms in brain metastases. The aim of this study was to investigate the differences in the molecular mechanisms involved in brain metastasis of breast and lung cancers. In addition, we aimed to identify cancer lineage-specific druggable targets in the brain metastasis.

Methods

To that aim, a cohort of 44 FFPE tissue samples, including 22 breast cancer and 22 lung adenocarcinoma (LUAD) and their matched-paired brain metastases were collected. Targeted gene expression profiles of primary tumors were compared to their matched-paired brain metastases samples using nCounter PanCancer IO 360™ Panel of NanoString technologies. Pathway analysis was performed using gene set analysis (GSA) and gene set enrichment analysis (GSEA). The validation was performed by using Immunohistochemistry (IHC) to confirm the expression of immune checkpoint inhibitors.

Results

Our results revealed the significant upregulation of cancer-related genes in primary tumors compared to their matched-paired brain metastases (adj. p ≤ 0.05). We found that upregulated differentially expressed genes in breast cancer brain metastasis (BM-BC) and brain metastasis from lung adenocarcinoma (BM-LUAD) were associated with the metabolic stress pathway, particularly related to the glycolysis. Additionally, we found that the upregulated genes in BM-BC and BM-LUAD played roles in immune response regulation, tumor growth, and proliferation. Importantly, we identified high expression of the immune checkpoint VTCN1 in BM-BC, and VISTA, IDO1, NT5E, and HDAC3 in BM-LUAD. Validation using immunohistochemistry further supported these findings.

Conclusion

In conclusion, the findings highlight the significance of using matched-paired samples to identify cancer lineage-specific therapies that may improve brain metastasis patients outcomes.

STING activation counters glioblastoma by vascular alteration and immune surveillance

Glioblastoma (GBM) is an aggressive brain tumor with a median survival of 15 months and has limited treatment options. Immunotherapy with checkpoint inhibitors has shown minimal efficacy in combating GBM, and large clinical trials have failed. New immunotherapy approaches and a deeper understanding of immune surveillance of GBM are needed to advance treatment options for this devastating disease. In this study, we used two preclinical models of GBM: orthotopically delivering either GBM stem cells or employing CRISPR-mediated tumorigenesis by adeno-associated virus, to establish immunologically proficient and non-inflamed tumors, respectively. After tumor development, the innate immune system was activated through long-term STING activation by a pharmacological agonist, which reduced tumor progression and prolonged survival. Recruitment and activation of cytotoxic T-cells were detected in the tumors, and T-cell specificity towards the cancer cells was observed. Interestingly, prolonged STING activation altered the tumor vasculature, inducing hypoxia and activation of VEGFR, as measured by a kinome array and VEGF expression. Combination treatment with anti-PD1 did not provide a synergistic effect, indicating that STING activation alone is sufficient to activate immune surveillance and hinder tumor development through vascular disruption. These results guide future studies to refine innate immune activation as a treatment approach for GBM, in combination with anti-VEGF to impede tumor progression and induce an immunological response against the tumor.

Tumor lineage-specific immune response in brain metastatic disease: opportunities for targeted immunotherapy regimen?

Metastases in the brain are the most severe and devastating complication of cancer. The incidence of brain metastasis is increasing. Therefore, the need of finding specific druggable targets for brain metastasis is demanding. The aim of this study was to compare the brain (immune) response to brain metastases of the most common tumor lineages, viz., lung adenocarcinoma and breast cancer. Targeted gene expression profiles of 11 brain metastasis of lung adenocarcinoma (BM-LUAD) were compared to 11 brain metastasis of breast cancer (BCBM) using NanoString nCounter PanCancer IO 360™ Panel. The most promising results were validated spatially using the novel GeoMx™ Digital Spatial Profiler (DSP) Technology. Additionally, Immune cell profiles and expression of drug targets were validated by multiplex immunohistochemistry. We found a more active immune response in BM-LUAD as compared to BCBM. In the BM-LUAD, 138 genes were upregulated as compared to BCBM (adj. p ≤ 0.05). Conversely, in BCBM 28 genes were upregulated (adj. p ≤ 0.05). Additionally, genes related to CD45 + cells, T cells, and cytotoxic T cells showed to be expressed higher in BM-LUAD compared to BCBM (adj. p = 0.01, adj. p = 0.023, adj. p = 0.023, respectively). The spatial quantification of the immune cells using the GeoMx DSP technique revealed the significantly higher quantification of CD14 and CD163 in tumor regions of BM-LUAD as compared to BCBM. Importantly, the immune checkpoint VISTA and IDO1 were identified as highly expressed in the BM-LUAD. Multiplex immunohistochemistry confirmed the finding and showed that VISTA is expressed mainly in BM-LUAD tumor cells, CD3 + cells, and to fewer levels in some microglial cells in BM-LUAD. This is the first report on differences in the brain immune response between metastatic tumors of different lineages. We found a far more extensive infiltration of immune cells in BM-LUAD as compared to BCBM. In addition, we found higher expression of VISTA and IDO1 in BM-LUAD. Taken together, targeted immune therapy should be considered to treat patients with BM-LUAD.

Associated Factors of Spontaneous Hemorrhage in Brain Metastases in Patients with Lung Adenocarcinoma

BACKGROUND

Hemorrhage in brain metastases (BMs) from lung cancer is common and associated with a poor prognosis. Research on associated factors of spontaneous hemorrhage in patients with BMs is limited. This study aimed to investigate the predictive risk factors for BM hemorrhage and assess whether hemorrhage affects patient survival.

METHODS

We retrospectively evaluated 159 BMs from 80 patients with lung adenocarcinoma from January 2017 to May 2022. Patients were classified into hemorrhagic and non-hemorrhagic groups. Patient demographics, lung cancer molecular subtype, treatment type, and tumor-node-metastasis stage were compared between the groups. Multivariate generalized estimating equation (GEE) analysis and gradient boosting were performed. To determine whether BM hemorrhage can stratify overall survival after BM (OSBM), univariate survival analysis was performed.

RESULTS

In the univariate analysis, hemorrhagic BMs were significantly larger and had a history of receiving combination therapy with tyrosine kinase inhibitor (TKI) and intracranial radiation (p < 0.05). Multivariate GEE showed that tumor size and combination therapy were independent risk factors for BM hemorrhage (p < 0.05). Gradient boosting demonstrated that the strongest predictor of BM hemorrhage was tumor size (variable importance: 49.83), followed by age (16.65) and TKI combined with intracranial radiation (13.81). There was no significant difference in OSBM between the two groups (p = 0.33).

CONCLUSIONS

Hemorrhage in BMs from lung adenocarcinomas may be associated with BM tumor size and a combination of TKI and intracranial radiotherapy. BM hemorrhage did not affect OSBM.

Vascular complications in patients with brain tumors

PURPOSE OF REVIEW

Venous thromboembolism (VTE) and other vascular events are common in patients with brain tumors, but their optimal management is not firmly established, in large part due to the competing risk of intracranial hemorrhage (ICH) in this population.

RECENT FINDINGS

There is conflicting evidence on whether therapeutic anticoagulation increases the risk of ICH in patients with brain tumors, with several metanalysis and retrospective cohort studies showing an increased risk and others showing no differences. Current guidelines recommend anticoagulating brain tumors patients with VTE with either low-molecular weight heparin (LMWH) or direct oral anticoagulants (DOACs), and several retrospective studies have shown the risk of ICH with DOACs is similar or smaller than with LMWH.

SUMMARY

An increased risk of VTE exists in a variety of brain tumor types. Most patients with brain tumors and VTE should receive therapeutic anticoagulation, and recent retrospective evidence supports the use of both LMWH and DOACs as effective and relatively safe in this setting. Patients with brain tumors are also at increased risk of other vascular tumor- or treatment-related complications whose optimal management is unclear.

Treatment-Limiting Decisions in Patients with Spontaneous Intracerebral Hemorrhage

Background and Objectives: Treatment-limiting decisions (TLDs) are employed to actively withhold treatment/invasive interventions from patients in whom clinicians feel they would derive little to no benefit and/or suffer detrimental effects. Data regarding the employment of TLDs in patients with spontaneous intracerebral hemorrhage (ICH) remain sparse. Accordingly, this study sought to investigate both the prevalence of TLDs and factors driving TLDs in patients suffering from spontaneous ICH. Materials and Methods: This was a retrospective study of 249 consecutive patients with ICH treated from 2018−2019 at the Neurovascular Center of the University Hospital Bonn. Reasons deemed critical in the decision-making process with regard to TLD were ultimately extracted/examined via chart review of qualifying patients. Results: A total of 249 patients with ICH were included within the final analyses. During the time period examined, 49 patients (20%) had advanced directives in place, whereas in 53 patients (21%) consultation with relatives or acquaintances was employed before further treatment decisions. Overall, TLD ultimately manifested in 104 patients (42%). TLD was reached within 6 h after admission in 52 patients (50%). Congruent with severity of injury and expected outcomes, TLDs were more likely in patients with signs of cerebral herniation and an ICH score > 3 (p < 0.001). Conclusions: The present study examines details associated with TLDs in patients with spontaneous ICH. These data provide insight into key decisional processes and reinforce the need for further structured investigations in an effort to help guide patients and their families.