Kris A. Smith

Relative Cerebral Blood Volume Values to Differentiate High-Grade Glioma Recurrence from Posttreatment Radiation Effect: Direct Correlation between Image-Guided Tissue Histopathology and Localized Dynamic Susceptibility-Weighted Contrast-Enhanced Perfusion MR Imaging Measurements

BACKGROUND AND PURPOSE: Differentiating tumor growth from posttreatment radiation effect (PTRE) remains a common problem in neuro-oncology practice. To our knowledge, useful threshold relative cerebral blood volume (rCBV) values that accurately distinguish the 2 entities do not exist. Our prospective study uses image-guided neuronavigation during surgical resection of MR imaging lesions to correlate directly specimen histopathology with localized dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging (DSC) measurements and to establish accurate rCBV threshold values, which differentiate PTRE from tumor recurrence. MATERIALS AND METHODS: Preoperative 3T gradient-echo DSC and contrast-enhanced stereotactic T1-weighted images were obtained in patients with high-grade glioma (HGG) previously treated with multimodality therapy. Intraoperative neuronavigation documented the stereotactic location of multiple tissue specimens taken randomly from the periphery of enhancing MR imaging lesions. Coregistration of DSC and stereotactic images enabled calculation of localized rCBV within the previously recorded specimen locations. All tissue specimens were histopathologically categorized as tumor or PTRE and were correlated with corresponding rCBV values. All rCBV values were T1-weighted leakage-corrected with preload contrast-bolus administration and T2/T2*-weighted leakage-corrected with baseline subtraction integration. RESULTS: Forty tissue specimens were collected from 13 subjects. The PTRE group (n = 16) rCBV values ranged from 0.21 to 0.71, tumor (n = 24) values ranged from 0.55 to 4.64, and 8.3% of tumor rCBV values fell within the PTRE group range. A threshold value of 0.71 optimized differentiation of the histopathologic groups with a sensitivity of 91.7% and a specificity of 100%. CONCLUSIONS: rCBV measurements obtained by using DSC and the protocol we have described can differentiate HGG recurrence from PTRE with a high degree of accuracy.

Reevaluating the imaging definition of tumor progression: perfusion MRI quantifies recurrent glioblastoma tumor fraction, pseudoprogression, and radiation necrosis to predict survival

INTRODUCTION: Contrast-enhanced MRI (CE-MRI) represents the current mainstay for monitoring treatment response in glioblastoma multiforme (GBM), based on the premise that enlarging lesions reflect increasing tumor burden, treatment failure, and poor prognosis. Unfortunately, irradiating such tumors can induce changes in CE-MRI that mimic tumor recurrence, so called post treatment radiation effect (PTRE), and in fact, both PTRE and tumor re-growth can occur together. Because PTRE represents treatment success, the relative histologic fraction of tumor growth versus PTRE affects survival. Studies suggest that Perfusion MRI (pMRI)–based measures of relative cerebral blood volume (rCBV) can noninvasively estimate histologic tumor fraction to predict clinical outcome. There are several proposed pMRI-based analytic methods, although none have been correlated with overall survival (OS). This study compares how well histologic tumor fraction and OS correlate with several pMRI-based metrics. METHODS: We recruited previously treated patients with GBM undergoing surgical re-resection for suspected tumor recurrence and calculated preoperative pMRI-based metrics within CE-MRI enhancing lesions: rCBV mean, mode, maximum, width, and a new thresholding metric called pMRI–fractional tumor burden (pMRI-FTB). We correlated all pMRI-based metrics with histologic tumor fraction and OS. RESULTS: Among 25 recurrent patients with GBM, histologic tumor fraction correlated most strongly with pMRI-FTB (r = 0.82; P < .0001), which was the only imaging metric that correlated with OS (P<.02). CONCLUSION: The pMRI-FTB metric reliably estimates histologic tumor fraction (i.e., tumor burden) and correlates with OS in the context of recurrent GBM. This technique may offer a promising biomarker of tumor progression and clinical outcome for future clinical trials.

An extent of resection threshold for recurrent glioblastoma and its risk for neurological morbidity

OBJECT Despite improvements in the medical and surgical management of patients with glioblastoma, tumor recurrence remains inevitable. For recurrent glioblastoma, however, the clinical value of a second resection remains uncertain. Specifically, what proportion of contrast-enhancing recurrent glioblastoma tissue must be removed to improve overall survival and what is the neurological cost of incremental resection beyond this threshold? METHODS The authors identified 170 consecutive patients with recurrent supratentorial glioblastomas treated at the Barrow Neurological Institute from 2001 to 2011. All patients previously had a de novo glioblastoma and following their initial resection received standard temozolomide and fractionated radiotherapy. RESULTS The mean clinical follow-up was 22.6 months and no patient was lost to follow-up. At the time of recurrence, the median preoperative tumor volume was 26.1 cm(3). Following re-resection, median postoperative tumor volume was 3.1 cm(3), equating to an 87.4% extent of resection (EOR). The median overall survival was 19.0 months, with a median progression-free survival following re-resection of 5.2 months. Using Cox proportional hazards analysis, the variables of age, Karnofsky Performance Scale (KPS) score, and EOR were predictive of survival following repeat resection (p = 0.0001). Interestingly, a significant survival advantage was noted with as little as 80% EOR. Recursive partitioning analysis validated these findings and provided additional risk stratification at the highest levels of EOR. Overall, at 7 days after surgery, a deterioration in the NIH stroke scale score by 1 point or more was observed in 39.1% of patients with EOR ≥ 80% as compared with 16.7% for those with EOR < 80% (p = 0.0049). This disparity in neurological morbidity, however, did not endure beyond 30 days postoperatively (p = 0.1279). CONCLUSIONS For recurrent glioblastomas, an improvement in overall survival can be attained beyond an 80% EOR. This survival benefit must be balanced against the risk of neurological morbidity, which does increase with more aggressive cytoreduction, but only in the early postoperative period. Interestingly, this putative EOR threshold closely approximates that reported for newly diagnosed glioblastomas, suggesting that for a subset of patients, the survival benefit of microsurgical resection does not diminish despite biological progression.

TREATMENT OPTIONS FOR THIRD VENTRICULAR COLLOID CYSTS: COMPARISON OF OPEN MICROSURGICAL VERSUS ENDOSCOPIC RESECTION

OBJECTIVEWe retrospectively reviewed our experience treating third ventricular colloid cysts to compare the efficacy of endoscopic and transcallosal approaches. METHODSBetween September 1994 and March 2004, 55 patients underwent third ventricular colloid cyst resection. The transcallosal approach was used in 27 patients; the endoscopic approach was used in 28 patients. Age, sex, cyst diameter, and presence of hydrocephalus were similar between the two groups. RESULTSThe operating time and hospital stay were significantly longer in the transcallosal craniotomy group compared with the endoscopic group. Both approaches led to reoperations in three patients. The endoscopic group had two subsequent craniotomies for residual cysts and one repeat endoscopic procedure because of equipment malfunction. The transcallosal craniotomy group had two reoperations for fractured drainage catheters and one operation for epidural hematoma evacuation. The transcallosal craniotomy group had a higher rate of patients requiring a ventriculoperitoneal shunt (five versus two) and a higher infection rate (five versus none). Intermediate follow-up demonstrated more small residual cysts in the endoscopic group than in the transcallosal craniotomy group (seven versus one). Overall neurological outcomes, however, were similar in the two groups. CONCLUSIONCompared with transcallosal craniotomy, neuroendoscopy is a safe and effective approach for removal of colloid cysts in the third ventricle. The endoscope can be considered a first-line treatment for these lesions, with the understanding that a small number of these patients may need an open craniotomy to remove residual cysts.

The impact of adjuvant stereotactic radiosurgery on atypical meningioma recurrence following aggressive microsurgical resection

OBJECT Patients with atypical meningioma often undergo gross-total resection (GTR) at initial presentation, but the role of adjuvant radiation therapy remains unclear. The increasing prevalence of stereotactic radiosurgery (SRS) in the modern neurosurgical era has led to the use of routine postoperative radiation therapy in the absence of evidence-based guidelines. This study sought to define the long-term recurrence rate of atypical meningiomas and identify the value of SRS in affecting outcome. METHODS The authors identified 228 patients with microsurgically treated atypical meningiomas who underwent a total of 257 resections at the Barrow Neurological Institute over the last 20 years. Atypical meningiomas were diagnosed according to current WHO criteria. Clinical and radiographic data were collected retrospectively. RESULTS Median clinical and radiographic follow-up was 52 months. Gross-total resection, defined as Simpson Grade I or II resection, was achieved in 149 patients (58%). The median proliferative index was 6.9% (range 0.4%-20.6%). Overall 51 patients (22%) demonstrated tumor recurrence at a median of 20.2 months postoperatively. Seventy-one patients (31%) underwent adjuvant radiation postoperatively, with 32 patients (14%) receiving adjuvant SRS and 39 patients (17%) receiving adjuvant intensity modulated radiation therapy (IMRT). The recurrence rate for patients receiving SRS was 25% (8/32) and for IMRT was 18% (7/39), which was not significantly different from the overall group. Gross-total resection was predictive of progression-free survival (PFS; relative risk 0.255, p < 0.0001), but postoperative SRS was not associated with improved PFS in all patients or in only those with subtotal resections. CONCLUSIONS Atypical meningiomas are increasingly irradiated, even after complete or near-complete microsurgical resection. This analysis of the largest patient series to date suggests that close observation remains reasonable in the setting of aggressive microsurgical resection. Although postoperative adjuvant SRS did not significantly affect tumor recurrence rates in this experience, a larger cohort study with longer follow-up may reveal a therapeutic benefit in the future.

Correlations between Perfusion MR Imaging Cerebral Blood Volume, Microvessel Quantification, and Clinical Outcome Using Stereotactic Analysis in Recurrent High-Grade Glioma

BACKGROUND AND PURPOSE: Quantifying MVA rather than MVD provides better correlation with survival in HGG. This is attributed to a specific “glomeruloid” vascular pattern, which is better characterized by vessel area than number. Despite its prognostic value, MVA quantification is laborious and clinically impractical. The DSC-MR imaging measure of rCBV offers the advantages of speed and convenience to overcome these limitations; however, clinical use of this technique depends on establishing accurate correlations between rCBV, MVA, and MVD, particularly in the setting of heterogeneous vascular size inherent to human HGG. MATERIALS AND METHODS: We obtained preoperative 3T DSC-MR imaging in patients with HGG before stereotactic surgery. We histologically quantified MVA, MVD, and vascular size heterogeneity from CD34-stained 10-μm sections of stereotactic biopsies, and we coregistered biopsy locations with localized rCBV measurements. We statistically correlated rCBV, MVA, and MVD under conditions of high and low vascular-size heterogeneity and among tumor grades. We correlated all parameters with OS by using Cox regression. RESULTS: We analyzed 38 biopsies from 24 subjects. rCBV correlated strongly with MVA (r = 0.83, P < .0001) but weakly with MVD (r = 0.32, P = .05), due to microvessel size heterogeneity. Among samples with more homogeneous vessel size, rCBV correlation with MVD improved (r = 0.56, P = .01). OS correlated with both rCBV (P = .02) and MVA (P = .01) but not with MVD (P = .17). CONCLUSIONS: rCBV provides a reliable estimation of tumor MVA as a biomarker of glioma outcome. rCBV poorly estimates MVD in the presence of vessel size heterogeneity inherent to human HGG.

Intraoperative Confocal Microscopy for Brain Tumors: A Feasibility Analysis in Humans

BACKGROUND: The ability to diagnose brain tumors intraoperatively and identify tumor margins during resection could maximize resection and minimize morbidity. Advances in optical imaging enabled production of a handheld intraoperative confocal microscope. OBJECTIVE: To present a feasibility analysis of the intraoperative confocal microscope for brain tumor resection. METHODS: Thirty-three patients with brain tumor treated at Barrow Neurological Institute were examined. All patients received an intravenous bolus of sodium fluorescein before confocal imaging with the Optiscan FIVE 1 system probe. Optical biopsies were obtained within each tumor and along the tumor-brain interfaces. Corresponding pathologic specimens were then excised and processed. These data was compared by a neuropathologist to identify the concordance for tumor histology, grade, and margins. RESULTS: Thirty-one of 33 lesions were tumors (93.9%) and 2 cases were identified as radiation necrosis (6.1%). Of the former, 25 (80.6%) were intra-axial and 6 (19.4%) were extra-axial. Intra-axial tumors were most commonly gliomas and metastases, while all extra-axial tumors were meningiomas. Among high-grade gliomas, vascular neoproliferation, as well as tumor margins, were identifiable using confocal imaging. Meningothelial and fibrous meningiomas were distinct on confocal microcopy-the latter featured spindle-shaped cells distinguishable from adjacent parenchyma. Other tumor histologies correlated well with standard neuropathology tissue preparations. CONCLUSION: Intraoperative confocal microscopy is a practicable technology for the resection of human brain tumors. Preliminary analysis demonstrates reliability for a variety of lesions in identifying tumor cells and the tumor-brain interface. Further refinement of this technology depends upon the approval of tumor-specific fluorescent contrast agents for human use.

In vivo intraoperative confocal microscopy for real-time histopathological imaging of brain tumors.

OBJECT Frozen-section analysis is the current standard for the intraoperative diagnosis of brain tumors. Intraoperative confocal microscopy is an emerging technology with the potential to visualize tumor histopathological features and cell morphology in real time. The authors report their findings using this new intraoperative technology in vivo with sodium fluorescein contrast during the course of 50 microsurgical tumor resections. METHODS Eighty-eight regions were visualized with confocal microscopy, and corresponding biopsy samples were examined with routine neuropathological analysis. The tumors studied included meningiomas, schwannomas, gliomas of various grades, and a hemangioblastoma. The confocal microscopic features of each tumor and of various artifacts inherent to the technology were documented. A pathologist working in a blinded fashion reviewed a subset of the images in a further evaluation of the usefulness of the device as a diagnostic tool. RESULTS Overall, intraoperative confocal imaging correlated surprisingly well with corresponding traditional histological findings, including the identification of many pathognomonic cytoarchitectural features of various brain tumors. In the blinded study, 26 (92.9%) of 28 lesions were diagnosed correctly. CONCLUSIONS Further study will be necessary for better definition of the role of intraoperative confocal microscopy as a routine adjunct for intraoperative brain tumor diagnosis.

The selective GABAB antagonist CGP-35348 blocks spike-wave bursts in the cholesterol synthesis rat absence epilepsy model

Slow IPSPs, which are believed to be involved in generation of the wave of spike-wave epileptiform discharges, are mediated by the GABAB receptor. We therefore examined the effect of the GABAB antagonist, Ciba Geigy Product, CGP-35348, in the cholesterol synthesis inhibitor model of absence epilepsy in rat. Rats received Ayerst-9944 (AY-9944), from 6-45 mg i.p. in the first few weeks of life. By 2 months after AY-9944 administration these rats exhibited recurrent spike-waves and behavioral arrests. In 10 such animals CGP-35348 was administered intraperitoneally in doses of 0 (vehicle), 10, 25 or 100 mg/kg. EEG recordings were obtained via previously implanted bone screws. Technologists blinded to treatment group counted spike-waves over a 4 h period post-injection. The average number of spike-wave burst seconds per 4 h of recording for all dosages and times was 52.4 +/- 81.4 (mean +/- S.D.) s. Mean burst times (seconds) were vehicle = 93.5 +/- 106.5; 10 mg/kg = 69.9 +/- 79.7; 25 mg/kg = 30.8 +/- 46.9; 100 mg/kg = 15.2 +/- 54, a mean 84% reduction at 100 mg/kg (ANOVA regression significant at 0.0001). Spike-waves were suppressed for at least 4 h after injection of CGP-35348. These findings supplement similar findings in other absence models, and support a potential role for GABAB antagonists in treatment of absence seizures.

Self-inflicted orbital and intracranial injury with a retained foreign body, associated with psychotic depression: case report and review.

Reports of intracranial self-mutilation by psychotic individuals are associated with severe mental disorders, criminality, or both. We describe a psychotically depressed male who drove a ballpoint pen through his right medial canthus and into his intracranial compartment. The patient developed a cavernous sinus syndrome and a traumatic dissection of the cavernous portion of the carotid artery. The pen was removed intraoperatively. Postoperatively, the patient was placed on a course of broad-spectrum antibiotics, antidepressants, and antipsychotic medications, and he has received long-term psychiatric follow-up. The literature related to these unusual cases is reviewed, and relevant surgical, medical, and psychiatric aspects of treatment are discussed.