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Michael W McDermott

Publications and source records attributed to Michael W McDermott.

At least 19 recordsLinked to original sources
PubMed2007

Expression of the hypoxia marker carbonic anhydrase 9 is associated with anaplastic phenotypes in meningiomas.

PURPOSE: Hypoxia in the tumor microenvironment triggers a variety of genetic and adaptive responses that regulate tumor growth. Tumor hypoxia is often associated with more malignant phenotypes, resistance to therapy, and poor survival. The purpose of this study was to evaluate the prevalence of hypoxia in meningiomas using the endogenous hypoxia marker carbonic anhydrase 9 (CA9) and to relate the expression of CA9 to tumor vascularity, histopathologic grade, and clinical variables, such as recurrent tumor status. EXPERIMENTAL DESIGN: Expression of CA9 and CD34, an endothelial cell marker, was examined in serial paraffin-embedded sections by immunohistochemistry in 25 grade 1, 17 grade 2, and 20 grade 3 meningiomas. Areas of immunoreactivity were semiquantitatively scored and correlated to clinical variables using Statistical Analysis System statistical software. RESULTS: Approximately 50% (29 of 62) of all meningiomas contained regions of hypoxia as judged by expression of CA9, and this expression was significantly associated with higher-grade histology (P = 0.001). In contrast, vascularity, as assessed by the percentage of vascular hotspots, was inversely associated with tumor grade (P = 0.023) and was not associated with CA9 expression. Among lower-grade meningiomas, CA9 expression tended to be more common in recurrent tumors. CONCLUSIONS: Tumor hypoxia is an endogenous feature of meningiomas, and therapeutic regimens should include strategies to target the subpopulation of hypoxic as well as the normoxic cells within the tumor. Hypoxia in meningiomas is associated with an aggressive phenotype. Further studies to define the contribution of hypoxia to meningioma pathophysiology are warranted.

Adult↗
PubMed2006

A genetic strategy to overcome the senescence of primary meningioma cell cultures.

Even though meningiomas are the second most common brain tumor in adults, little is known about the molecular basis of their growth and development. The lack of suitable cell culture model systems is an impediment to this understanding. Most studies on meningiomas rely on primary, early passage cell lines that eventually senesce or a few established cell lines that have been derived from aggressive variants of meningiomas. We have isolated three primary meningioma cell lines that are negative for telomerase activity. We can overcome the senescence of a Grade III derived meningioma cell line by expressing the telomerase catalytic subunit (hTERT), whereas Grade I meningioma cell lines require the expression of the human papillomavirus E6 and E7 oncogenes in conjunction with hTERT. Meningioma cell lines, immortalized in this manner, maintain their pre-transfection morphology and form colonies in vitro. We have confirmed the meningothelial origin of these cell lines by assessing expression of vimentin and desmoplakin, characteristic markers for meningiomas. Additionally, we have karyotyped these cell lines using array CGH and shown that they represent a spectrum of the genetic diversity seen in primary meningiomas. Thus, these cell lines represent novel cellular reagents for investigating the molecular oncogenesis of meningiomas.

Biomarkers, Tumor↗
PubMed2006

Assessment of image guided accuracy in a skull model: comparison of frameless stereotaxy techniques vs. frame-based localization.

INTRODUCTION: The use of image-guided systems (IGS) for brain biopsy has increased in neurosurgical practice. We sought to evaluate the accuracy of a plastic, disposable burr hole mounted guide for stereotactic biopsy using an IGS and compare the results of different targeting methods with those of frame based localization. METHODS: MRIs were performed on a skull model with mounted fiducials with a stereotactic frame in place and data was loaded onto the Stealth IGS. The model was placed in a Mayfield head holder and fixed to the OR table. Registration of imaging to physical space was carried out. Using three different targeting methods on the Stealth IGS, the distance between the target and the predicted position of the target, the offset error, was measured in three dimensions and confirmed by 2 observers. A sum of squares for the 3 offset errors in all planes was used to calculate the summed vector error. The same MRI dataset used with the Cosman-Roberts-Wells (CRW) stereotactic frame for comparison. The summed vector error was calculated in the same manner to compare the accuracy of targeting with these guides to the frame-based CRW system. RESULTS: For frameless stereotaxy using the "Straight- guide 4 2D" targeting method the mean error was 2.58 +/- 0.51 mm (n=12). The vector error was 5.23 +/- 0.54 (n=4). For the registration set and target using the "Offset- guide 4 2D" targeting method the mean error was 1.66 +/- 0.36 mm (n=12). The vector error was 3.32 +/- 0.72 (n=4). The best localization was obtained with the "probe's eye" planning and targeting. The mean error was 0.33 +/- 0.16 mm (n=12). The vector error was 1.0 +/- 0.28 (n=4). We found a statistical difference between the different techniques (P<0.001) (Kruskal-Wallis One Way Analysis of Variance on Ranks). An all pairwise multiple comparison procedure (Holm-Sidak method) found an overall significance level = 0.05. For the frame-based CRW the mean error from the target was 1.03 +/- 0.19 mm (n=18) and the mean target localization error vector was 2.23 +/- 0.14 (n=6). We found a statistically significant difference between NDT guide "Probes Eye" vs. the MR-CRW (P=0.003, Mann-Whitney Rank Sum Test). CONCLUSIONS: These results indicate that using MR imaging, surgical planning software and the skull mounted Navigus-DT with the probe's eye view option for targeting, localization accuracy appears to fall within acceptable ranges compared with frame-based methods which have been the standards for stereotactic brain biopsy and functional neurosurgery. Furthermore, there may be considerable differences in accuracy between different targeting methods.

Biopsy↗
PubMed2006

Management of a sporadic malignant subfrontal peripheral nerve sheath tumor.

Malignant subfrontal (olfactory) peripheral nerve sheath tumors (MPNSTs) are exceedingly rare. Although meningiomas are the most common subfrontal extra-axial lesions, it is important to recognize that MPNSTs, which are radiographically similar to meningiomas, can also be present in this location. MPNSTs require more aggressive surgical and postoperative management than meningiomas. In this paper, we describe a patient with a subfrontal MPNST with unusual histological characteristics and present a review of the literature. A 49-year-old woman presented with chronic sinusitis and progressive headaches. A neurological examination revealed left-sided anosmia. Brain-imaging studies revealed a large left subfrontal mass with extension into the frontal and ethmoid sinuses and the nasal cavity. The patient underwent both a bifrontal transbasal craniotomy and a transnasal approach for an attempt at total resection of both the intradural and extradural components of the MPNST. The patient was treated postoperatively with radiation therapy, and had no evidence of recurrence at her follow-up examination 1-year after treatment. Subfrontal PNSTs are extremely rare and usually benign. The specific cell and nerve of origin for these tumors remains unknown. Our case shows that these rare lesions can present as a malignant variant and thus require aggressive surgical and postoperative management to provide long-term tumor control.

Adult↗
PubMed2006

Meningioma.

Total excision is an appropriate treatment option for patients with benign meningiomas that are resectable with minimal morbidity. It is particularly appropriate for patients with significant mass effect causing symptoms. Fractionated conformal radiotherapy is an appropriate primary treatment option for patients with benign meningiomas of all sizes and all sites. It is particularly appropriate and preferred for optic nerve sheath meningiomas, for which there are few alternatives. Planned subtotal resection is appropriate if decompression is expected to relieve acute symptoms. After subtotal resection, it is appropriate to offer single-fraction radiosurgery or multifraction radiotherapy, depending on the size, location, and extent of residual tumor, so as to achieve progression-free survival and cause-specific survival rates comparable to those of other approaches.

Dose Fractionation, Radiation↗
PubMed2006

Extended bifrontal craniotomy for midline anterior fossa meningiomas: minimization of retraction-related edema and surgical outcomes.

OBJECTIVE: Meningiomas of the anterior cranial base can be approached with a variety of techniques. The extended bifrontal approach is often thought to be associated with increased morbidity because of the need for extensive removal of the bone and longer surgical times. The authors have attempted to quantitate retraction-related edema occurring after surgery to determine whether the extra bone removal limits retraction and reduces the chance of brain injury. METHODS: Charts were reviewed for patients who underwent extended bifrontal craniotomies performed for meningiomas at the University of California, San Francisco, between 1997 and 2005. Magnetic resonance imaging scans obtained before and after surgery were reviewed for brain edema as indicated by fluid-attenuated inversion recovery/T2 abnormality and grouped into four categories: A, no edema; B, edema restricted to the gyrus rectus; C, edema beyond the gyrus rectus; and D, extensive bifrontal edema. RESULTS: Forty-five patients were identified. Fifty-four percent of patients had tumors with a diameter of more than 4 cm. Simpson Grade 2 or 3 resection was achieved in 82% of patients, and the average operative time was 12.3 hours. Vision outcome was favorable in 74% of patients. Extent of fluid-attenuated inversion recovery abnormality remained unchanged in 87.5%, with 91% of patients in categories A or B edema remaining in those categories after surgery. There were no infections and there were two cerebrospinal fluid leaks. CONCLUSION: The extended bifrontal approach is a safe surgical procedure with limited morbidity that the authors think: 1) prevents secondary brain injury from excessive retraction; 2) offers great flexibility of view for the surgeon; and 3) should be considered the preferred approach compared with the standard bifrontal craniotomy for large tumors of the anterior cranial base.

Adult↗
PubMed2006

Salvage of infected craniotomy bone flaps with the wash-in, wash-out indwelling antibiotic irrigation system. Technical note and case series of 12 patients.

OBJECT: When complicated by infection, craniotomy bone flaps are commonly removed, discarded, and delayed cranioplasty is performed. This treatment paradigm is costly, carries the risks associated with additional surgery, and may cause cosmetic deformities. The authors present their experience with an indwelling antibiotic irrigation system used for the sterilization and salvage of infected bone flaps as an alternative to their removal and replacement. METHODS: The authors retrospectively reviewed the medical records for 12 patients with bone flap infections following craniotomy who received treatment with the wash-in, wash-out indwelling antibiotic irrigation system. Infected flaps were removed and scrubbed with povidone-iodine solution and soaked in 1.5% hydrogen peroxide while the wound was debrided. The bone flaps were returned to the skull and the irrigation system was installed. Antibiotic medication was infused through the system for a mean of 5 days. Intravenous antibiotic therapy was continued for 2 weeks and oral antibiotics for 3 months postoperatively. Wound checks were performed at clinic follow-up visits, and there was a mean follow-up period of 13 months. Eleven of the 12 patients who had undergone placement of the bone flap irrigation system experienced complete resolution of the infection. In five patients there was involvement of the nasal sinus cavities, and in four there was a history of radiation treatment. In the one patient whose infection recurred, there was both involvement of the nasal sinuses and a history of extensive radiation treatment. CONCLUSIONS: Infected bone flaps can be salvaged, thus avoiding the cost, risk, and possible disfigurement associated with flap removal and delayed cranioplasty. Although prior radiation treatment and involvement of the nasal sinuses may interfere with wound healing and clearance of the infection, these factors should not preclude the use of irrigation with antibiotic agents for bone flap salvage.

Adult↗
PubMed2005

Meningioma transcript profiles reveal deregulated Notch signaling pathway.

Meningiomas constitute the second most common central nervous system tumor, and yet relatively little is known about the molecular events that are important for the pathogenesis and malignant progression of these tumors. We have used serial analysis of gene expression to compare the transcriptomes of nonneoplastic meninges and meningiomas of all malignancy grades. A novel finding from this screen is the induction of three components of the Notch signaling pathway: the transcription factor, hairy and enhancer of Split1 (HES1) and two members of the Groucho/transducin-like enhancer of Split family of corepressors, TLE2 and TLE3. TLE corepressors interact and modulate the activity of a wide range of transcriptional regulatory systems, one of which is HES1. We have shown that the transcript and protein levels of HES1, the Notch2 and Notch1 receptors and the Jagged1 ligand are induced in meningiomas of all grades, whereas induction of TLE2 and TLE3 occurs specifically in higher-grade meningiomas. Meningioma cell lines express components of the Notch signaling pathway and an inhibitor of this pathway suppresses meningioma cell survival. These results suggest that deregulated expression of the Notch pathway is a critical event in meningioma pathogenesis and that modulation of this and potentially other signaling pathways by TLE corepressors leads to a more malignant phenotype.

Basic Helix-Loop-Helix Proteins↗
PubMed2005

Prizes, lectures, and awards of the American Association of Neurological Surgeons/Congress of Neurological Surgeons Section on Tumors.

An important goal of the Section on Tumors of the American Association of Neurological Surgeons (AANS) and Congress of Neurological Surgeons (CNS) since its founding in 1985 has been to foster both education and research in the field of brain tumor treatment. As one means of achieving this, the Section awards a number of prizes, research grants, and named lectures at the annual meetings of the AANS and CNS. After a brief examination of similar honors that were given in recognition of pioneering work by Knapp, Cushing, and other early brain tumor researchers, the authors describe the various awards given by the AANS/CNS Section on Tumors since its founding, their philanthropic donors, and the recipients of the awards. The subsequent career of the recipients is briefly examined, in terms of the rate of full publication of award-winning abstracts and achievement of grant funding by awardees.

Awards and Prizes↗
PubMed2005

Frame-based stereotactic biopsy remains an important diagnostic tool with distinct advantages over frameless stereotactic biopsy.

OBJECT: As the availability of image-guided surgical navigation systems has increased, the application of frame-based biopsy has declined at our institution, despite equivalent accuracy and safety. There are several cost issues separating the use of surgical navigation systems and stereotactic frames for simple biopsy which may have implications in this era of health care cost control. We retrospectively reviewed the UCSF experience with stereotactic brain biopsy from a 9 year period. METHODS: Data were collected for 213 consecutive stereotactic brain biopsies performed at UCSF (139 frame-based and 74 frameless). There were no significant differences between the frame-based and frameless biopsy groups with regard to patient demographics, overall histopathology, proportion of nondiagnostic biopsies, or incidence of complications. General anesthesia was used for 9 (6%) and 70 (95%) of the frame-based and frameless biopsy cases, respectively. Frame-based biopsies required a mean of 114+/-3 min of operating room time, while frameless biopsies required 185+/-6 min (P<0.0001). For patients admitted to our neurosurgery service who underwent frame-based (n=110) or frameless (n=52) biopsy within 24 h of admission, the mean lengths of hospital stay were 1.8+/-0.2 and 3.2+/-0.6 days, respectively (P=0.007). CONCLUSION: Frame-based and frameless stereotactic biopsy approaches were equally effective at providing a tissue diagnosis with minimum morbidity and mortality. The frame-based approach, however, required significantly less anesthesia resources, less operating room time and shorter hospital stays, and thus should still be considered a first-line approach for stereotactic brain biopsy.

Adolescent↗
PubMed2005

Techniques to assess the proliferative potential of brain tumors.

Assessment of brain tumor proliferative potential provides important prognostic information that supplements standard histopathologic grading. Many laboratories rely on mitotic figures to quantify the proliferative potential of brain tumors, but this conventional cellular proliferative index is subject to inter-observer variability and not consistently predictive for low-and high-grade tumors. Recent advancements in technology have made it possible to use proliferative indices as a standard supplement in pathology laboratories. Non-invasive tumor tissue measurements of cell proliferation can be performed using- bromodeoxyuridine labeling index (BrdU LI), flow cytometry (FCM), MIB-1 antibody to the Ki-67 antigen (MIB-1), proliferating cell nuclear antigen (PCNA), and argyrophilic nucleolar organizing regions (AgNOR). Each of these assays has been described in the literature with respect to its ability to predict tumor grade or outcome. At the present time MIB-1 and AgNOR are the simplest and most reliable of these techniques. In addition, advances in our understanding of the genetic alterations associated with proliferation promise to provide more specific markers of proliferative potential. Beyond the pathology laboratory, radiographic studies such as positron emission tomography (PET), single photon emission computed tomography (SPECT), and most recently magnetic resonance spectroscopy (MRS) have been used as follow-up measures, assessing response to treatment and tumor recurrence, rather than as predictors of response to treatment. These radiographic tools, however, have the potential to provide an assessment of tumor proliferation without the need for invasive measures. In this article, we present a review of the current techniques utilized to understand the proliferative potential of brain tumors.

Animals↗
PubMed2005

Sex steroid and growth factor profile of a meningioma associated with pregnancy.

BACKGROUND: Increased growth of meningiomas during pregnancy as well as postpartum clinical regression of symptoms have been reported but remain poorly understood. A better understanding of the factors that contribute to these observations, including potential factors associated with pregnancy, could enable design of more effective adjuvant therapies. METHODS: We describe the presentation of a meningioma during the immediate postpartum period. Serial imaging demonstrated subsequent rapid decrease in size of the tumour prior to any intervention. The lesion was resected, and the tissue was subjected to immunostaining for gene products associated with pregnancy, including estrogen receptor (ER), progesterone receptor (PR), platelet-derived growth factor receptor B (PDGFRB), fibroblastic growth factor receptor 2 (FGFR-2), epidermal growth factor receptor (EGFR) and human placental lactogen (hPL). RESULTS: The lesion proved to be an atypical fibroblastic meningioma grade II (WHO). Immunostaining demonstrated significant staining for PR, PDGFRB, and FGFR-2. No specific staining for ER, EGFR, or hPL was identified. CONCLUSION: Although clinical regression of meningioma following pregnancy is well-recognized, imaging data are much less abundant. This report provides clear clinical and imaging documentation of a meningioma associated with pregnancy. In addition, the growth factor profile of this tumour suggests the importance of PR, PDGFRB, and FGFR-2 as potential therapeutic targets.

Adult↗
PubMed2005

Skull base chondrosarcoma originating from the petroclival junction.

OBJECTIVE: To define the presentation of patients with skull base chondrosarcoma, to elucidate surgical strategies, and to identify the role of postoperative radiotherapy. STUDY DESIGN: Retrospective review. SETTING: Tertiary referral center. PATIENTS: All patients (n = 33) with skull base chondrosarcoma managed at our institution. The average follow-up time was 7.7 years (range, 0-20 years). MAIN OUTCOME MEASURES: Tumor location, presenting symptoms, presence of residual or recurrent tumor, and mortality. RESULTS: The most common tumor location was the petroclival junction (n = 29). Common presenting symptoms were diplopia (48%) and headache (45%). Surgical approaches included retrosigmoid, transtemporal, transfacial, and frontotemporal craniotomies. Biopsy only was performed in four patients, subtotal resection in 19 patients, and total resection in nine patients. Most patients received postoperative radiotherapy (82%). Follow-up revealed residual, stable disease in 28% of patients and recurrent disease in 24% of patients. The mean time to recurrence was 3.0 +/- 2.8 years. The lack of postoperative radiation was significantly correlated with an increased risk of recurrence (odds ratio, 28; p = 0.007) but incomplete tumor resection was not (p = 0.6). Life-table analysis revealed that the 5-year survival rate was 85% and the 10-year survival rate was 77%. Five patients died; four of the deaths attributable to recurrent disease. CONCLUSION: The characteristic growth pattern of skull base chondrosarcoma is tumor eroding the petroclival junction. Current therapeutic strategy is resection through an extradural subtemporal craniotomy with removal of the petrous apex and clivus. Radical resection of uninvolved structures is often not necessary. Nonetheless, gross total removal is often achievable. Postoperative radiotherapy reduces the chance of tumor recurrence.

Adult↗
PubMed2005

Radiosurgery in metastatic brain cancer.

Radiosurgery offers patients with brain metastases an effective and minimally invasive treatment modality. Radiosurgery provides local tumor control and prolongs survival in select patients with brain metastases. This review will discuss numerous aspects of radiosurgery, including the various delivery techniques and radiobiology. Treatment recommendations will be outlined in view of the available clinical data. Although surgery or radiosurgery with whole-brain radiotherapy remains an important option for patients with a solitary brain metastasis, radiosurgery with or without whole-brain radiotherapy should be considered in patients with a limited number of small tumors and a good prognosis.

Brain Neoplasms↗
PubMed2005

Prognostic significance of intracranial dissemination of glioblastoma multiforme in adults.

OBJECT: The clinical outcome and treatment of adult patients with disseminated intracranial glioblastoma multiforme (GBM) is unclear. The objective in the present study was to assess the prognostic significance of disseminated intracranial GBM in adults at presentation and at the time of tumor progression. METHODS: Clinical data from 1491 patients older than 17 years and harboring a GBM that had been diagnosed between 1988 and 1998 at the University of California at San Francisco neurooncology clinic were retrospectively reviewed. Dissemination of the GBM (126 patients) was determined based on Gd-enhanced magnetic resonance images. Classification of dissemination was as follows: Type I, single lesion with subependymal or subarachnoid spread; Type II, multifocal lesions without subependymal or subarachnoid spread; and Type III, multifocal lesions with subependymal or subarachnoid spread. Subgroups of patients were compared using Kaplan-Meier curves that depicted survival probability. The median postprogression survival (PPS), defined according to neuroimaging demonstrated dissemination, was 37 weeks for Type I (23 patients), 25 weeks for Type II (50 patients), and 10 weeks for Type III spread (19 patients). Patients with dissemination at first tumor progression (52 patients) overall had a shorter PPS than those in a control group with local progression, after adjusting for age, Kamofsky Performance Scale score, and time from tumor diagnosis to its progression (311 patients). When analyzed according to tumor dissemination type, PPS was significantly shorter in patients with Type II (33 patients, p < 0.01) and Type III spread (11 patients, p < 0.01) but not in those with Type I spread (eight patients, p = 0.18). CONCLUSIONS: Apparently, the presence of intracranial tumor dissemination on initial diagnosis does not in itself preclude aggressive treatment if a patient is otherwise well. A single focus of GBM that later demonstrates Type I dissemination on progression does not have a worse prognosis than a lesion that exhibits only local recurrence.

Adult↗
PubMed2005

Craniotomy for meningioma in the United States between 1988 and 2000: decreasing rate of mortality and the effect of provider caseload.

OBJECT: The goal of this study was to determine the risk of adverse outcomes after contemporary surgical treatment of meningiomas in the US and trends in patient outcomes and patterns of care. METHODS: The authors performed a retrospective cohort study by using the Nationwide Inpatient Sample covering the period of 1988 to 2000. Multivariate regression models with disposition end points of death and hospital discharge were used to test patient, surgeon, and hospital characteristics, including volume of care, as outcome predictors. Multivariate analyses revealed that larger-volume centers had lower mortality rates for patients who underwent craniotomy for meningioma (odds ratio [OR] 0.74, 95% confidence interval [CI] 0.59-0.93, p = 0.01). Adverse discharge disposition was also less likely at high-volume hospitals (OR 0.71, 95% CI 0.62-0.80, p < 0.001). With respect to the surgeon caseload, there was a trend toward a lower rate of mortality after surgery when higher-caseload providers were involved, and a significantly less frequent adverse discharge disposition (OR 0.71, 95% CI 0.62-0.80, p < 0.001). The annual meningioma caseload in the US increased 83% between 1988 and 2000, from 3900 patients/year to 7200 patients/year. In-hospital mortality rates decreased 61%, from 4.5% in 1988 to 1.8% in 2000. Reductions in the mortality rates were largest at high-volume centers (a 72% reduction in the relative mortality rate at largest-volume-quintile centers, compared with a 6% increase in the relative mortality rate at lowest-volume-quintile centers). The number of US hospitals where craniotomies were performed for meningiomas increased slightly. Fewer centers hosted one meningioma resection annually, whereas the largest centers had disproportionate increases in their caseloads, indicating a modest centralization of meningioma surgery in the US during this interval. CONCLUSIONS: The mortality and adverse hospital discharge disposition rates were lower when meningioma surgery was performed by high-volume providers. The annual US caseload increased, whereas the mortality rates decreased, especially at high-volume centers.

Adult↗
PubMed2005

Serial diffusion-weighted magnetic resonance imaging in cases of glioma: distinguishing tumor recurrence from postresection injury.

OBJECT: Diffusion-weighted magnetic resonance (MR) imaging is an invaluable tool in the diagnosis of acute stroke and other types of brain injury. Abnormalities in and around the resection cavity on diffusion-weighted imaging have been observed following surgery for infiltrating glioma. The purpose of this study was to investigate prospectively the incidence, time course, and ultimate outcome of these abnormalities. METHODS: Forty-four consecutive patients with newly diagnosed gliomas were prospectively observed using serial MR imaging including diffusion-weighted sequences. Clinical and surgical data were also collected. Immediately postoperatively neuroimaging identified 28 patients (64%) in whom areas of reduced diffusion appeared in or around the resection cavity (mean volume 8.2 +/- 1.5 cm3). Complete resolution of this reduced diffusion was demonstrated within 90 days in 24 patients (86%). On subsequent neuroimages these areas demonstrated Gd enhancement as early as postoperative Day 15 and as late as Day 198 and ultimately took on the appearance of encephalomalacia in 26 (93%) of 28 cases. Postoperative reduced diffusion was not predicted by the clinical or surgical parameters that were assessed. No clinical deficits were attributable to the reduced diffusion. CONCLUSIONS: An abnormality related to diffusion-weighted sequences on postoperative MR imaging can occur after resection of newly diagnosed gliomas. In this study the abnormality typically resolved and was replaced by contrast enhancement on follow-up imaging, ultimately demonstrating encephalomalacia on long-term follow up. Findings on neuroimaging during the period of enhancement could be confused with recurrent tumor and interpreted as early treatment failure. Based on the findings of this study the authors strongly suggest that the inclusion of diffusion-weighted sequences in postoperative MR imaging is essential, as is MR imaging immediately before radiation therapy to monitor disease progression. A new enhancement observed after glioma surgery should be interpreted in the context of the diffusion-weighted image obtained immediately postoperatively.

Adult↗