Glioma grading by using histogram analysis of blood volume heterogeneity from MR-derived cerebral blood volume maps.
OBJECTIVE
To retrospectively compare the diagnostic accuracy of an alternative method used to grade gliomas that is based on histogram analysis of normalized cerebral blood volume (CBV) values from the entire tumor volume (obtained with the histogram method) with that of the hot-spot method, with histologic analysis as the reference standard.


METHODS
The medical ethics committee approved this study, and all patients provided informed consent. Fifty-three patients (24 female, 29 male; mean age, 48 years; age range, 14-76 years) with histologically confirmed gliomas were examined with dynamic contrast material-enhanced 1.5-T magnetic resonance (MR) imaging. CBV maps were created and normalized to unaffected white matter (normalized CBV maps). Four neuroradiologists independently measured the distribution of whole-tumor normalized CBVs and analyzed this distribution by classifying the values into area-normalized bins. Glioma grading was performed by assessing the normalized peak height of the histogram distributions. Logistic regression analysis and interobserver agreement were used to compare the proposed method with a hot-spot method in which only the maximum normalized CBV was used.


RESULTS
For the histogram method, diagnostic accuracy was independent of the observer. Interobserver agreement was almost perfect for the histogram method (kappa = 0.923) and moderate for the hot-spot method (kappa = 0.559). For all observers, sensitivity was higher with the histogram method (90%) than with the hot-spot method (55%-76%).


CONCLUSIONS
Glioma grading based on histogram analysis of normalized CBV heterogeneity is an alternative to the established hot-spot method, as it offers increased diagnostic accuracy and interobserver agreement.
Emblem
Kyrre E
KE
Departments of Medical Physics, Rikshospitalet-Radiumhospitalet Medical Centre, Sognsvannsveien 20, N-0027 Oslo, Norway. kyrre.eeg.emblem@rikshospitalet.no
Nedregaard
Baard
B
Nome
Terje
T
Due-Tonnessen
Paulina
P
Hald
John K
JK
Scheie
David
D
Borota
Olivera Casar
OC
Cvancarova
Milada
M
Bjornerud
Atle
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D001810:Blood Volume; D001932:Brain Neoplasms / Q000473:pathology*; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D005260:Female; D005910:Glioma / Q000473:pathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D016015:Logistic Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009942:Organometallic Compounds; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol