Suprasellar Anterior-Posterior Diameter Optimizes the Use of Intraoperative MRI in Patients Undergoing Endoscopic Pituitary Surgery.

BACKGROUND AND OBJECTIVES: Intraoperative MRI (iMRI) has been demonstrated to improve the extent of resection of pituitary neuroendocrine tumors resected using endoscopic endonasal approaches. We sought to establish if preoperative clinicoradiological parameters could be used to predict which patients are most likely to benefit from iMRI and thus allow more efficient use of this technology. METHODS: A prospectively maintained surgical database of all endoscopic pituitary tumor resections with iMRI guidance performed between May 2017 and September 2023 was accessed. Data were collected on clinical and radiological parameters that may predict reintervention after iMRI. Logistic regression models were constructed to assess the relationship between predictor variables and reintervention after iMRI. RESULTS: Seventy-three patients were included in the study. After review of the iMRI, 24/73 (33%) patients underwent surgical reintervention. The combined rate of gross total resection/near total resection was 64/73 (88%). The rate of biochemical cure of endocrine disease after surgery for a hormonally active tumor was 15/21 (71%). On univariate logistic regression analysis, the only factor significantly associated with reintervention after iMRI was the suprasellar anterior-posterior diameter (odds ratio 1.1, 95% CI 1.01-1.2, P = .030). CONCLUSION: Suprasellar anterior-posterior diameter ≥15 mm predicts the requirement for reintervention after endoscopic resection of pituitary neuroendocrine tumor. Use of this easily obtained radiological parameter will allow iMRI to be used in those patients who are most likely to benefit.

Baseline total brain volume predicts changes in quality of life and overall survival after cranial radiotherapy in older patients with glioblastoma: Results from the prospective BRITER study.

Background: Short-course partial brain radiotherapy ± chemotherapy for older patients with GBM extends survival but there is no validated evidence for prediction of individual risk of acute radiotherapy-related side effects. Methods: This prospective multicentre observational trial recruited patients with newly diagnosed GBM aged ≥65 planned for cranial radiotherapy. Baseline MRI scans were analyzed for markers of brain resilience including relative total brain volume (ratio of cerebrospinal fluid (CSF) volume to total intracranial volume (TIV)) and their relationship to change in quality of life (QoL). Results: 126 patients enrolled: mean age 72 years (range 65-83). 77% had debulking surgery. 79% received radiotherapy with concurrent TMZ, and 21% received palliative radiotherapy alone. The median OS was 10.7 months. After accounting for age, sex, treatment, and baseline MoCA score, there was a relationship between baseline CSF:TIV and change in QoL score at 8 weeks post treatment. For each unit point of increase in CSF:TIV, there was a corresponding decrease in QoL score of 1.72 (95% CI -3.24 to -0.19 P = .027). 35 participants were too unwell to complete questionnaires or had died by the 8 week follow-up visit. In this subgroup, post hoc logistic regression showed baseline CSF:TIV was related to the risk of non-attendance (OR 1.35, 95% CI 1.01 to 1.80, P = .042). Cox regression models showed baseline CSF:TIV was associated with worsened OS (HR 1.41, 95% CI 1.19 to 1.66, P < .001). Conclusions: This study provides evidence to support the use of an imaging biomarker to help assess the risk:benefit ratio for radiotherapy.

Immune checkpoint inhibitor treatment of brain metastasis associated with a less invasive growth pattern, higher T-cell infiltration and raised tumor ADC on diffusion weighted MRI.

BACKGROUND: Brain metastases are the most common intracranial tumors with an increasing incidence. They are an important cause of morbidity and mortality in patients with solid organ cancer and a focus of recent clinical research and experimental interest. Immune checkpoint inhibitors are being increasingly used to treat solid organ cancers. METHODS: To determine whether immune checkpoint inhibitors were biologically effective in the brain, we compared melanoma brain metastasis samples where treatment with ipilimumab had occurred preoperatively to those who had not received any immune modulating therapy and looked for histopathological (invasion, vascularity, metastasis inducing proteins, matrix metalloproteinases, immune cell infiltration, tissue architecture) and advanced MRI differences (diffusion weighted imaging). RESULTS: Co-localized tissue samples from the same regions as MRI regions of interest showed significantly lower vascularity (density of CD34 + vessels) in the core and higher T-cell infiltration (CD3 + cells) in the leading edge for ipilimumab-treated brain metastasis samples than for untreated cases and this correlated with a higher tumor ADC signal at post-treatment/preoperative MRI brain. CONCLUSIONS: Treatment of a melanoma brain metastasis with ipilimumab appears to cause measurable biological changes in the tumor that can be correlated with post-treatment diffusion weighted MRI imaging, suggesting both a mechanism of action and a possible surrogate marker of efficacy.

The Role of the Immune Response in Brain Metastases: Novel Imaging Biomarkers for Immunotherapy.

Brain metastases are a major clinical problem, and immunotherapy offers a novel treatment paradigm with the potential to synergize with existing focal therapies like surgery and radiosurgery or even replace them in future. The brain is a unique microenvironment structurally and immunologically. The immune response is likely to be crucial to the adaptation of systemic immune modulating agents against this disease. Imaging is frequently employed in the clinical diagnosis and management of brain metastasis, so it is logical that brain imaging techniques are investigated as a source of biomarkers of the immune response in these tumors. Current imaging techniques in clinical use include structural MRI (post-contrast T1W sequences, T2, and FLAIR), physiological sequences (perfusion- and diffusion-weighted imaging), and molecular imaging (MR spectroscopy and PET). These are reviewed for their application to predicting and measuring the response to immunotherapy in brain metastases.

3 Tesla intra-operative MRI as an adjunct to endoscopic pituitary surgery: an early assessment of clinical utility.

BACKGROUND: Extent of resection is a major determinant of outcomes following pituitary surgery. Intra-operative magnetic resonance imaging (iMRI), provides an immediate assessment of the extent of resection, allowing further tumour resection during the same procedure. However, such systems are expensive and significantly increase operative time, prompting some authors to question the additional benefit conferred by iMRI when combined with endoscopy. Our aim was to assess the impact of combining 3 T iMRI with endoscopy in patients with pituitary tumours. METHODS: We retrospectively reviewed a prospectively maintained database to identify patients who underwent iMRI guided endoscopic resection of pituitary tumours between May 2017 and November 2018 (iMRI cohort). This cohort was compared with a pre-iMRI cohort of patients who underwent endoscopic resection of pituitary adenomas. Operative time, extent of resection, control of endocrine disease and post-operative complications were recorded and analysed. RESULTS: Thirty-seven patients were included in each cohort. iMRI facilitated additional tumour resection in 6/37 (16%) of cases. In 4/37 cases (11%), iMRI prompted a return to theatre but no further tumour could be identified. The overall GTR rate, following iMRI was 24/37 (65%) as compared to 21/37 (57%) in the pre-iMRI cohort. Cure of endocrine disease associated with hormonally active tumours was achieved in 9/11 (82%) of cases in the iMRI cohort. The mean operative time in the iMRI cohort was 327 minutes (five hours 27 minutes). CONCLUSIONS: 3 T iMRI provides immediate identification of residual tumour following endoscopic pituitary surgery. This allows for resection of surgically accessible residual disease during the same procedure and is likely to reduce the requirement for later re-intervention. However, the use of iMRI in this setting is associated with significant resource allocation issues which must be considered prior to the widespread adoption of this technique.

Utilization of volumetric magnetic resonance imaging for baseline and surveillance imaging in Neuro-oncology.

The acquisition of volumetric post-contrast MRI has clear advantages in the interpretation of neuro-oncology studies but has yet to find its way into routine clinical practice beyond planning scans for surgery and radiotherapy. This commentary briefly highlights the benefits of these techniques whilst dispelling some of the perceived disadvantages.

A Review of the Current Evidence on Gadolinium Deposition in the Brain.

Over the past 3 years, gadolinium-based contrast agents have been linked to MRI signal changes in the brain, which have been found to be secondary to gadolinium deposition in the brain, particularly in the dentate nuclei and globus pallidus even in patients having an intact blood-brain barrier and a normal renal function. This tends to occur more in linear agents than with macrocyclic agents. Nonetheless, there has been no significant evidence that this has any clinical consequence. We reviewed the current evidence related to this new phenomenon and the precautionary approach taken by regulatory agencies.

T-Cell Densities in Brain Metastases Are Associated with Patient Survival Times and Diffusion Tensor MRI Changes.

Brain metastases are common and are usually detected by MRI. Diffusion tensor imaging (DTI) is a derivative MRI technique that can detect disruption of white matter tracts in the brain. We have matched preoperative DTI with image-guided sampling of the brain-tumor interface in 26 patients during resection of a brain metastasis and assessed mean diffusivity and fractional anisotropy (FA). The tissue samples were analyzed for vascularity, inflammatory cell infiltration, growth pattern, and tumor expression of proteins associated with growth or local invasion such as Ki67, S100A4, and MMP2, 9, and 13. A lower FA in the peritumoral region indicated more white matter tract disruption and independently predicted longer overall survival times (HR for death = 0.21; 95% confidence interval, 0.06-0.82; P = 0.024). Of all the biological markers studied, only increased density of CD3+ lymphocytes in the same region correlated with decreased FA (Mann-Whitney U, P = 0.037) as well as confounding completely the effect of FA on multivariate survival analyses. We conclude that the T-cell response to brain metastases is not a surrogate of local tumor invasion, primary cancer type, or aggressive phenotype and is associated with patient survival time regardless of these biological factors. Furthermore, it can be assayed by DTI, potentially offering a quick, noninvasive, clinically available method to detect an active immune microenvironment and, in principle, to measure susceptibility to immunotherapy.Significance: These findings show that white matter tract integrity is degraded in areas where T-cell infiltration is highest, providing a noninvasive method to identify immunologically active microenvironments in secondary brain tumors. Cancer Res; 78(3); 610-6. ©2017 AACR.

Management of Typical and Atypical Hangman's Fractures.

Study Design Retrospective study of a prospectively maintained database. Objective Our aim was to retrospectively review management and outcomes of patients with low-grade hangman's fractures, specifically looking at differences in outcomes between collars and halo immobilization. We also studied fracture patterns and their treatment outcomes. Methods Forty-one patients with hangman's fractures were identified from 105 patients with axis fractures between 2007 and 2013. Typical hangman's fractures were defined as traumatic spondylolisthesis of the axis causing a bilateral pars interarticularis fracture. Fractures involving the posterior cortex of C2 on one or both sides or an asymmetrical pattern were defined as atypical. Results There were 41 patients with a mean age of 59 years, with 13 (31.7%) typical and 28 (68.2%) atypical fractures. There were 22 (53.6%) type 1 fractures, 7 (41.4%) type 2 fractures, and 2 (4.9%) type 2a fractures in this series. Cervical collars were used to manage 11 patients (27% of all patients with hangman's fractures) and halo orthosis was used in 27 (65.8%). Three (7.3%) patients underwent surgical fixation of the fracture. Bony union was achieved in all patients on radiologic follow-up. Permanent neurologic deficit occurred in one patient due to associated injuries. Neck pain and stiffness were reported more commonly in the atypical group, but this finding was not statistically significant. Conclusions The majority of hangman type fractures can be treated nonoperatively. We found no difference in outcomes between a rigid collar or halo immobilization for treatment of low-grade fractures. Radiologic follow-up is essential to identify cases of nonunion.

Novel use of 4D-CTA in imaging of intranidal aneurysms in an acutely ruptured arteriovenous malformation: is this the way forward?

Ruptured arteriovenous malformation (AVM) is a frequent cause of intracranial hemorrhage. The presence of associated aneurysms, especially intranidal aneurysms, is considered to increase the risk of re-hemorrhage. We present two cases where an intranidal aneurysm was demonstrated on four-dimensional CT angiography (time-resolved CT angiography) (4D-CTA). These features were confirmed by digital subtraction angiography (catheter arterial angiogram). This is the first report of an intranidal aneurysm demonstrated by 4D-CTA. 4D-CTA can offer a comprehensive evaluation of the angioarchitecture and flow dynamics of an AVM for appropriate classification and management.

Quantification of structural changes in the corpus callosumin children with profound hypoxic-ischaemic brain injury.

BACKGROUND: Birth-related acute profound hypoxic-ischaemic brain injury has specific patterns of damage including the paracentral lobules. OBJECTIVE: To test the hypothesis that there is anatomically coherent regional volume loss of the corpus callosum as a result of this hemispheric abnormality. MATERIALS AND METHODS: Study subjects included 13 children with proven acute profound hypoxic-ischaemic brain injury and 13 children with developmental delay but no brain abnormalities. A computerised system divided the corpus callosum into 100 segments, measuring each width. Principal component analysis grouped the widths into contiguous anatomical regions. We conducted analysis of variance of corpus callosum widths as well as support vector machine stratification into patient groups. RESULTS: There was statistically significant narrowing of the mid-posterior body and genu of the corpus callosum in children with hypoxic-ischaemic brain injury. Support vector machine analysis yielded over 95% accuracy in patient group stratification using the corpus callosum centile widths. CONCLUSION: Focal volume loss is seen in the corpus callosum of children with hypoxic-ischaemic brain injury secondary to loss of commissural fibres arising in the paracentral lobules. Support vector machine stratification into the hypoxic-ischaemic brain injury group or the control group on the basis of corpus callosum width is highly accurate and points towards rapid clinical translation of this technique as a potential biomarker of hypoxic-ischaemic brain injury.

Accuracy of four-dimensional CT angiography in detection and characterisation of arteriovenous malformations and dural arteriovenous fistulas.

A retrospective review was made to assess the accuracy of four dimensional CT angiogram (4D-CTA) in diagnosis of arteriovenous malformations (AVM) and dural arteriovenous fistulas (DAVF), with catheter-based digital-subtraction angiogram (DSA) being gold standard. 33 pairs of investigations (DSA and 4D-CTA) were performed primarily for suspicion of AVM/DAVF. Based on blinded reports, sensitivity and specificity for detection of AVM/DAVF were 77% (95% CI: 46-95%) and 100% (95% CI: 83-100%) respectively. Positive predictive value was 100% (95% CI: 69-100%) and negative predictive value 87% (95% CI: 66-97%). 4D-CTA is a practical minimally-invasive technique for evaluating cerebrovascular pathologies. There is good agreement between the findings of 4D-CTA and DSA despite the differences in temporal and spatial resolutions. 4D-CTA may obviate the need for DSA in a subgroup of patients who would otherwise have undergone this invasive investigation, which carries a risk of important complications.

Novel use of 4D-CTA in imaging of intranidal aneurysms in an acutely ruptured arteriovenous malformation: is this the way forward?

Ruptured arteriovenous malformation (AVM) is a frequent cause of intracranial hemorrhage. The presence of associated aneurysms, especially intranidal aneurysms, is considered to increase the risk of re-hemorrhage. We present two cases where an intranidal aneurysm was demonstrated on four-dimensional CT angiography (time-resolved CT angiography) (4D-CTA). These features were confirmed by digital subtraction angiography (catheter arterial angiogram). This is the first report of an intranidal aneurysm demonstrated by 4D-CTA. 4D-CTA can offer a comprehensive evaluation of the angioarchitecture and flow dynamics of an AVM for appropriate classification and management.

Diffusion-weighted MRI characteristics of the cerebral metastasis to brain boundary predicts patient outcomes.

BACKGROUND: Diffusion-weighted MRI (DWI) has been used in neurosurgical practice mainly to distinguish cerebral metastases from abscess and glioma. There is evidence from other solid organ cancers and metastases that DWI may be used as a biomarker of prognosis and treatment response. We therefore investigated DWI characteristics of cerebral metastases and their peritumoral region recorded pre-operatively and related these to patient outcomes. METHODS: Retrospective analysis of 76 cases operated upon at a single institution with DWI performed pre-operatively at 1.5T. Maps of apparent diffusion coefficient (ADC) were generated using standard protocols. Readings were taken from the tumor, peritumoral region and across the brain-tumor interface. Patient outcomes were overall survival and time to local recurrence. RESULTS: A minimum ADC greater than 919.4 × 10(-6) mm(2)/s within a metastasis predicted longer overall survival regardless of adjuvant therapies. This was not simply due to differences between the types of primary cancer because the effect was observed even in a subgroup of 36 patients with the same primary, non-small cell lung cancer. The change in diffusion across the tumor border and into peritumoral brain was measured by the "ADC transition coefficient" or ATC and this was more strongly predictive than ADC readings alone. Metastases with a sharp change in diffusion across their border (ATC >0.279) showed shorter overall survival compared to those with a more diffuse edge. The ATC was the only imaging measurement which independently predicted overall survival in multivariate analysis (hazard ratio 0.54, 95% CI 0.3 - 0.97, p = 0.04). CONCLUSIONS: DWI demonstrates changes in the tumor, across the tumor edge and in the peritumoral region which may not be visible on conventional MRI and this may be useful in predicting patient outcomes for operated cerebral metastases.

The role of magnetic resonance imaging in the management of brain metastases: diagnosis to prognosis.

This article reviews the different MRI techniques available for the diagnosis, treatment and monitoring of brain metastases with a focus on applying advanced MR techniques to practical clinical problems. Topics include conventional MRI sequences and contrast agents, functional MR imaging, diffusion weighted MR, MR spectroscopy and perfusion MR. The role of radiographic biomarkers is discussed as well as future directions such as molecular imaging and MR guided high frequency ultrasound.

Distinguishing optic neuritis in neuromyelitis optica spectrum disease from multiple sclerosis: a novel magnetic resonance imaging scoring system.

BACKGROUND: The management of acute optic neuritis differs according to the underlying etiology and techniques which may help with early differential diagnosis are therefore of considerable value. OBJECTIVE: We wanted to determine if multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) could be differentiated on the basis of neuroimaging abnormalities of the anterior visual pathways following an episode of optic neuritis. METHODS: Magnetic resonance imaging (MRI) findings of 27 patients diagnosed with MS (n = 15) or NMOSD (n = 12), who presented with acute isolated optic neuritis over a 3-year period, were reviewed retrospectively. The extent and location of inflammation along the anterior visual pathways were analyzed. A novel scoring system was devised, based upon the number of anatomical segments involved. RESULTS: Patients with NMOSD had a relative risk of 7.5 (confidence interval: 0.3-17.3) of having a score of 4 or more. Only NMOSD patients were found to have a score of 6 or higher. A trend for more posterior involvement of the anterior visual pathways was noted in the NMOSD group. CONCLUSION: This pilot study suggests that the MRI-based scoring system described here may aid in distinguishing patients with optic neuritis who have MS vs NMOSD. Visual pathway inflammation in NMOSD patients appears to be more extensive than in MS, mirroring the longitudinally extensive spinal cord lesions found in neuromyelitis optica.

The time course and phenotype of Uhthoff phenomenon following optic neuritis.

As there is little information regarding the recovery from Uhthoff phenomenon (UP) in the multiple sclerosis (MS) literature, the objective of this study was to assess the phenotypes of UP. A one-page questionnaire was sent to 80 consecutive optic neuritis (ON) patients seen in a tertiary neuro-ophthalmology clinic. Of the 48 responders to the questionnaire, 52% reported experiencing UP, with a range of follow-up from 1 to 20 years. Only 16% had resolution of UP, all this occurred within 8 weeks of the onset of ON. Of the MS patients with UP, 88% experienced non-visual heat-related phenomenon compared with 30% without UP. The presence of UP may have a more general phenotypic significance. If full recovery from UP has not occurred within the first 2 months from the onset of ON, then recovery appears to be uncommon and may therefore be a surrogate marker of remyelination in future drug trials.

CT pulmonary angiography combined with echocardiography in suspected systemic sclerosis-associated pulmonary arterial hypertension.

OBJECTIVE: Echocardiography is widely used in the investigation of patients with suspected SSc-associated pulmonary arterial hypertension (SSc-PAH). We investigated whether CT pulmonary angiography (CTPA) provides additive diagnostic value. METHODS: Data for 89 consecutive patients with suspected SSc-PAH undergoing echocardiography, CTPA and right heart catheterization were reviewed. Pulmonary artery diameter (dPA) and ascending aorta diameter (dAA), right and left ventricular diameter (dRV and dLV) and grade of tricuspid regurgitation (TR(CT)) measured at CTPA and tricuspid gradient (TG(ECHO)) at echocardiography were retrieved. A predictive equation for mean pulmonary arterial pressure (mPAP) was derived using multivariate linear regression. Multivariate Cox regression analysis was then used to assess the prognostic strength of CTPA parameters and TG(ECHO). RESULTS: Absolute measures of dPA and dRV correlated weakly with mPAP. However, dPA : dAA and dRV : dLV showed stronger correlations with mPAP (dPA : dAA r = 0.42, P < 0.001; dRV : dLV r = 0.51, P < 0.001). dRV : dLV correlated more strongly with pulmonary vascular resistance than did dPA : dAA (r = 0.63 vs 0.39, P both <0.001). dPA : dAA and TG(ECHO) were independent predictors of mPAP. A derived CT/echo composite index had a higher predictive accuracy (area under the curve = 0.95) than dPA : dAA or TG(ECHO) although negative predictive value (NPV) was only 77%. Combining the CT/echo composite index with presence or absence of TR(CT) increased NPV to 100% although this observation requires further validation. dRV : dLV was the strongest prognostic factor. CONCLUSION: In suspected SSc-PAH, cardiac chamber and great vessel measurements at CTPA correlate with pulmonary haemodynamics and predict survival. In combination with echocardiography CTPA increases diagnostic accuracy and may identify other potential causes of breathlessness.