Published ahead of print on June 26, 2008
doi: 10.3174/ajnr.A1182
Histogram Analysis of MR Imaging–Derived Cerebral Blood Volume Maps: Combined Glioma Grading and Identification of Low-Grade Oligodendroglial Subtypes
K.E. Emblema,e,
D. Scheieb,
P. Due-Tonnessenc,
B. Nedregaardc,
T. Nomec,
J.K. Haldc,
K. Beiskeb,
T.R. Melingd and
A. Bjorneruda,f
a Department of Medical Physics, Rikshospitalet University Hospital, Oslo, Norway
b The Pathology Clinic, Rikshospitalet University Hospital, Oslo, Norway
c Department of Neuroradiology, Rikshospitalet University Hospital, Oslo, Norway
d Department of Neurosurgery, Rikshospitalet University Hospital, Oslo, Norway
e The Interventional Centre, Rikshospitalet University Hospital, Oslo, Norway
f Department of Physics, University of Oslo, Oslo, Norway
View larger version (80K):
[in this window]
[in a new window]
|
Fig 1. A, Axial T2-weighted fast spin-echo (FSE) image (TR/TE, 4000/104 ms) of a patient (subject 3) with a low-grade oligoastrocytoma without LOH on 1p/19q. B, Axial postcontrast T1-weighted spin-echo (SE) image (TR/TE, 500/7.7 ms) of subject 3. C, Coregistered rCBV map of subject 3. D, Axial T2-weighted FSE image (TR/TE, 4000/104 ms) of a patient (subject 7) with a low-grade oligoastrocytoma with LOH on 1p/19q. E, Axial postcontrast T1-weighted SE image (TR/TE, 500/7.7 ms) of subject 7. F, Coregistered rCBV map of subject 7. Note the low rCBV values in the tumor area in image C compared with the tumor area in image F, typical of low-grade oligodendroglial tumors without LOH on 1p/19q. The corresponding normalized histogram signatures are shown in Fig 2.
| |
View larger version (10K):
[in this window]
[in a new window]
|
Fig 2. Resulting normalized histogram plots of the total distribution of rCBV values from the patients shown in Fig 1. The higher peak height of the low-grade oligoastrocytoma without LOH on p/19q, shown in a dotted line (subject 3, Fig 1A–C), indicates a more homogeneous rCBV distribution than the rCBV distribution of a low-grade oligoastrocytoma with LOH on 1p/19q, shown in a solid line (subject 7, Fig 1D–F).
| |
View larger version (13K):
[in this window]
[in a new window]
|
Fig 3. Mean histogram peak heights with SEs of the mean for the different glioma types investigated. The values are as follows: HGG = 0.052 (0.004), LGG = 0.094 (0.004), all high-grade oligodendroglial tumors (HGO) = 0.068 (0.010), low-grade oligodendroglial tumor with LOH on 1p/19q (LGO[–]) = 0.096 (0.004), low-grade oligodendroglial tumor without LOH on 1p/19q (LGO[+]) = 0.113 (0.002), and low-grade diffuse astrocytoma (LGA) = 0.086 (0.012). The oligodendroglial tumors include both oligodendrogliomas and oligoastrocytomas.
| |
View larger version (19K):
[in this window]
[in a new window]
|
Fig 4. A scatterplot showing histogram peak heights for the 52 patients included in our study. The histogram method is able to significantly differentiate between HGGs ( ) and LGGs (+) (P < .001), with an ICC of 0.902.
| |
View larger version (36K):
[in this window]
[in a new window]
|
Fig 5. Histogram peak heights for the 52 patients investigated in our study (23 LGGs and 29 HGGs). Each histogram peak height is a mean value across the 4 observers. With a cutoff value of 0.107, the sensitivity and specificity when distinguishing the 6 patients with low-grade oligodendroglial tumors without LOH on 1p/19q (red bars) from the other 46 patients (blue bars) are 100% (6/6) and 91% (42/46), respectively.
| |
View larger version (11K):
[in this window]
[in a new window]
|
Fig 6. ROC curve for the histogram method when distinguishing patients with low-grade oligodendroglial tumors without LOH on 1p/19q (n = 6) from the other gliomas (n = 46). The area (±SE) under the ROC curve is Az = 0.931 ± .036.
| |
