Faculty Bibliography

We have tested the predictive value of apparent diffusion coefficient (ADC) histogram analysis in stratifying progression-free survival (PFS) and overall survival (OS) in bevacizumab-treated patients with recurrent glioblastoma multiforme (GBM) from the multi-center BRAIN study. Available MRI's from patients enrolled in the BRAIN study (n = 97) were examined by generating ADC histograms from areas of enhancing tumor on T1 weighted post-contrast images fitted to a two normal distribution mixture curve. ADC classifiers including the mean ADC from the lower curve (ADC-L) and the mean lower curve proportion (LCP) were tested for their ability to stratify PFS and OS by using Cox proportional hazard ratios and the Kaplan-Meier method with log-rank test. Mean ADC-L was 1,209 x 10(-6)mm(2)/s +/- 224 (SD), and mean LCP was 0.71 +/- 0.23 (SD). Low ADC-L was associated with worse outcome. The hazard ratios for 6-month PFS, overall PFS, and OS in patients with less versus greater than mean ADC-L were 3.1 (95 % confidence interval: 1.6, 6.1; P = 0.001), 2.3 (95 % CI: 1.3, 4.0; P = 0.002), and 2.4 (95 % CI: 1.4, 4.2; P = 0.002), respectively. In patients with ADC-L <1,209 and LCP >0.71 versus ADC-L >1,209 and LCP <0.71, there was a 2.28-fold reduction in the median time to progression, and a 1.42-fold decrease in the median OS. The predictive value of ADC histogram analysis, in which low ADC-L was associated with poor outcome, was confirmed in bevacizumab-treated patients with recurrent GBM in a post hoc analysis from the multi-center (BRAIN) study.

Perfusion imaging of brain tumors has been performed by using various tracer and nontracer modalities and can provide additional physiologic and hemodynamic information, which is not available with routine morphologic imaging. Tumor vascular perfusion parameters obtained by using CT or MR perfusion have been used for tumor grading, prognosis, and treatment response in addition to differentiating treatment/radiation effects and non-neoplastic lesions from neoplasms. This article is an overview of the utility of PCT for assessment of brain tumors and describes the technique, its advantages, and limitations.

To describe the morphologic magnetic resonance imaging (MRI) findings in histologically proven therapy-induced cerebral necrosis. We retrospectively reviewed the morphologic MRI findings in patients with therapy-induced cerebral necrosis. Images were reviewed for size, location, and characteristics of signal intensity abnormalities and T1-contrast enhancement. Images were also assessed for mass effect, necrosis, cyst, atrophy, cortical thinning, and leukoencephalopathy. The individual imaging characteristics were correlated with clinical and treatment variables. There were 44 patients. Seventy percent had a glioma, all patients had received radiation, and 57% had received chemotherapy in close proximity to radiation. All images demonstrated contrast enhancement, predominantly in the white matter. Enhancement was present in the periventricular/subependymal region in 50% of cases and the corpus callosum in 27%. The most common pattern of lesion peripheral enhancement was "spreading wavefront" and of interior enhancement was "Swiss cheese/soap bubble." The enhancing lesion was single in 60% of cases. Mass effect was present in 93% of patients. Location and patterns of enhancement were significantly associated with the interval from brain radiation to the diagnosis of therapy-induced cerebral necrosis, tumor histology, patient age, type of radiation, and administration of systemic chemotherapy. This is the largest study of the morphologic conventional MRI findings in pathologically confirmed therapy-induced cerebral necrosis. We characterized the imaging findings in a variety of tumor types following a variety of radiation treatments and other antineoplastic therapy. These findings may be of value in identifying therapy-induced cerebral necrosis in patients treated for a brain tumor.

OBJECTIVE: The objective of our study was to analyze the use of screening cervical spine CT performed after trauma and establish the opportunity of potentially avoidable studies when evidence-based clinical criteria are applied before imaging. MATERIALS AND METHODS: All cervical spine CT examinations performed in the emergency department of a level 1 trauma center between January and December 2008 on adult patients with trauma were analyzed; 1589 studies were evaluated. Radiology reports and clinical data were reviewed for the presence of fracture or ligamentous injury and for the mode of injury. We also looked for documentation of clinical criteria used to perform the CT study. In particular, we looked for mention of posterior midline cervical tenderness, focal neurologic deficit, level of alertness, evidence of intoxication, and clinically apparent distracting injury. These five criteria were established by the National Emergency X-Radiography Utilization Study (NEXUS) to identify patients with a low probability of cervical spine injury who consequently needed no cervical spine imaging. RESULTS: Of the 1589 studies reviewed, 41 (2.6%) were positive for an acute cervical spine injury and 1524 (95.9%) were negative. The remaining 24 studies (1.5%) were indeterminate on the initial CT examination but subsequent imaging and clinical follow-up failed to show acute injury. Of the 1524 examinations with no acute injury, 364 (23.9%) had no documentation of any of the five NEXUS low-risk criteria. CONCLUSION: The strict application of the NEXUS low-risk criteria could potentially reduce the number of screening cervical spine CT examinations in the setting of trauma in more than 20% of cases, thereby avoiding a significant amount of unnecessary radiation and significant cost.

RATIONALE AND OBJECTIVES: The purpose of this study was to correlate the status of magnetic resonance contrast enhancement with immunohistologic vascular parameters such as microvascular cellular proliferation (MVCP), microvascular density (MVD), vascular endothelial growth factor receptor-2 (VEGFR-2) expression, and World Health Organization (WHO) grade obtained from image-guided biopsy specimens. We also compared perfusion computed tomography (PCT) parameters such as cerebral blood volume (CBV), cerebral blood flow (CBF), and permeability surface area-product (PS) with the presence or absence of contrast enhancement. MATERIALS AND METHODS: A total of 26 image-guided biopsy specimens in 16 patients with treatment naive gliomas were obtained from contrast-enhancing (CE) and nonenhancing (NE) regions of the glioma. Contrast enhancement status was correlated with MVD, MVCP, VEGFR-2 expression, and WHO grade obtained from the biopsy specimen as well as with the PCT parameters. RESULTS: Contrast enhancement showed statistically significant correlation with MVCP (P = .003) and PS (P = .007) when compared with various immunohistologic and perfusion vascular parameters. WHO grade of the biopsy specimen showed statistically significant correlation with contrast enhancement (P = .002), MVCP (P < .001), and PS values (P = .028). CONCLUSION: Contrast enhancement in gliomas is primarily from a break in blood-brain barrier as evidenced by its correlation with PS and MVCP, whereas it was not statistically correlated with CBV and MVD even though it showed a positive trend. Contrast enhancement also showed significant correlation with WHO grade suggesting a biopsy from CE region in a heterogeneous glioma probably will still yield the most aggressive part of the glioma is also shown by its association with MVCP and PS estimates.