Performance of Standardized Relative CBV for Quantifying Regional Histologic Tumor Burden in Recurrent High-Grade Glioma: Comparison against Normalized Relative CBV Using Image-Localized Stereotactic Biopsies.

BACKGROUND AND PURPOSE: Perfusion MR imaging measures of relative CBV can distinguish recurrent tumor from posttreatment radiation effects in high-grade gliomas. Currently, relative CBV measurement requires normalization based on user-defined reference tissues. A recently proposed method of relative CBV standardization eliminates the need for user input. This study compares the predictive performance of relative CBV standardization against relative CBV normalization for quantifying recurrent tumor burden in high-grade gliomas relative to posttreatment radiation effects. MATERIALS AND METHODS: We recruited 38 previously treated patients with high-grade gliomas (World Health Organization grades III or IV) undergoing surgical re-resection for new contrast-enhancing lesions concerning for recurrent tumor versus posttreatment radiation effects. We recovered 112 image-localized biopsies and quantified the percentage of histologic tumor content versus posttreatment radiation effects for each sample. We measured spatially matched normalized and standardized relative CBV metrics (mean, median) and fractional tumor burden for each biopsy. We compared relative CBV performance to predict tumor content, including the Pearson correlation (r), against histologic tumor content (0%-100%) and the receiver operating characteristic area under the curve for predicting high-versus-low tumor content using binary histologic cutoffs (≥50%; ≥80% tumor). RESULTS: Across relative CBV metrics, fractional tumor burden showed the highest correlations with tumor content (0%-100%) for normalized (r = 0.63, P < .001) and standardized (r = 0.66, P < .001) values. With binary cutoffs (ie, ≥50%; ≥80% tumor), predictive accuracies were similar for both standardized and normalized metrics and across relative CBV metrics. Median relative CBV achieved the highest area under the curve (normalized = 0.87, standardized = 0.86) for predicting ≥50% tumor, while fractional tumor burden achieved the highest area under the curve (normalized = 0.77, standardized = 0.80) for predicting ≥80% tumor. CONCLUSIONS: Standardization of relative CBV achieves similar performance compared with normalized relative CBV and offers an important step toward workflow optimization and consensus methodology.

Primary intramedullary spinal cord lymphoma.

OBJECTIVE: Among the rare causes of myelopathies is primary intramedullary spinal cord lymphoma (PISCL). As PISCL is often underrecognized, delaying appropriate treatment, we sought to describe its presentation, imaging characteristics, and outcomes. METHODS: Mayo Clinic medical records, lymphoma database, and autopsies from 1996 to 2009 were searched. Inclusion criteria were clinical myelopathic presentation, intramedullary spinal cord abnormalities, and pathologically confirmed CNS lymphoma. Exclusion criteria were extramedullary lymphoma, secondary intramedullary lymphoma, or other myelopathic etiology. Clinical features, diagnostic methods, neuroimaging, treatment, and outcomes were assessed. RESULTS: The 14 patients' median age at presentation was 62.5 years (range 41-82 years) and 10 were men (71%). Two had lymphoma risk factors (HIV infection 1; chronic immunosuppression postorgan transplant 1). Most had initial presumptive diagnoses of CNS demyelinating disease and definitive diagnosis of lymphoma was delayed a median of 8 months (range 1-22 months). CNS lymphoma was pathologically confirmed by biopsy (brain 6; spinal cord 4), CSF cytology (3), and autopsy (1). Most patients had multifocal, persistently enhancing lesions on spinal MRI and 8 had involvement of conus medullaris, cauda equina, or both. IV methotrexate was the initial treatment in 9 of 12 (75%) but lymphoma recurred in the majority. Half of the patients were wheelchair-dependent at 10 months and 2-year survival was 36%. CONCLUSIONS: PISCL mimics other causes of myelopathy. Spinal MRI demonstrating multifocal lesions, persistent gadolinium enhancement, and conus medullaris or cauda equina involvement is characteristic. Pathologic confirmation often requires CNS biopsy. Despite chemotherapy, morbidity and mortality is high.

Changes in ACh levels in the rat brain during subacute administration of diisopropylfluorophosphate.

Rats were treated with diisopropylfluorophosphate (DFP) acutely and daily for 14 days. The total, free, and bound acetylcholine (ACh) levels were monitored in striatum, hippocampus, and frontal cortex after DFP administration. Thirty minutes after daily administration of DFP, the total and free ACh levels were significantly increased and remained constant after each successive dose. The bound ACh levels in striatum and frontal cortex were also significantly increased; however, they were comparable to control levels after the 14th injection of DFP. The total ACh levels 30 min after a challenge dose of 2 mg/kg DFP in saline and DFP subacutely treated rats were significantly increased in hippocampus (34 and 76%) and frontal cortex (49 and 64%) and were not significantly different between the two groups. However, the level of total ACh in striatum was increased less in the tolerant rats (10%) than in the acutely treated rats (36%). The levels of free and bound ACh after acute administration of 2 mg/kg DFP were markedly increased in three brain regions. After subacute administration, the levels of bound ACh were significantly increased in hippocampus (84%) and frontal cortex (40%); however, that in striatum did not change. The increase in the bound ACh level in the subacute treatment group was less than that in acutely treated rats in all three brain regions; however, the duration of the elevation of the free ACh in striatum was shorter in subacutely treated rats. These results suggest that the presynaptic cholinergic storage sites for ACh might be changed during subacute administration of DFP.

Lymphatic and portal venous absorption of phenobarbital and thiopental in the dog.

Lymphatic and portal venous absorption of gastrically administered thiopental and phenobarbital were compared in the dog. Thiopental concentrations in lymph were significantly higher than phenobarbital concentrations for 30 min after drug administration. Disparity between portal plasma and lymph concentrations for thiopental during the first 15 min was about 1/3 as great as the same difference for phenobarbital. Thiopental displayed an average of twice the affinity for lipid (chylomicron) lymph as did phenobarbital. Because of its greater lipid solubility, thiopental is absorbed more by lymph than is phenobarbital. Both barbiturates are absorbed more quantitatively by the portal rather than lymphatic circulation, probably due to variation in the rate of flow of these 2 systems.

Regional and subcellular calmodulin content of rat brain.

Calmodulin contents of cortex, cerebellum, striatum, diencephalon, and medulla + pons and of subcellular fractions of each region were determined by radioimmunoassay. The diencephalon had the highest level of calmodulin (48.87 +/- 4.56 micrograms/mg protein), whereas medulla + pons had the lowest level (8.01 +/- 0.84 micrograms/mg protein). In all brain regions, the mitochondrial fraction was richest in calmodulin (from 71 to 227 micrograms/mg protein) whereas other areas contained from 6 to 66 micrograms/mg protein.