Andreas Stadlbauer1, Max Zimmermann1, Karl Rössler1, Stefan Oberndorfer2, Michael Buchfelder1, and Gertraud Heinz3
1Department of Neurosurgery, University of Erlangen, Erlangen, Germany, 2Department of Neurology, University Clinic of St. Pölten, St. Pölten, Austria, 3Department of Radiology, University Clinic of St. Pölten, St. Pölten, Austria
Synopsis
Early detection of recurrence is crucial in patient
care, but differentiation of treatment related necrosis from recurrent neoplasm
is often difficult with conventional MRI (cMRI). We evaluated the usefulness
for glioma recurrence grade increase detection of a multiparametric MRI for combined
exanimation of oxygen metabolism and microvessel architecture. Forty-one
patients with suspected recurrent glioma and one patient under antiangiogenic
therapy were examined using vascular architecture mapping (VAM) and
multiparametric quantitative BOLD (mp-qBOLD). 57% of LGG-patients, 22% of
glioma WHO°III, and 32% of glioblastoma patients which were diagnosed as
unsuspicious showed changes in oxygen metabolism and microvasculature indicative
for recurrence.Purpose
Early detection of recurrence is crucial in patient
care. According to the RANO criteria, increase in contrast material enhancement
with worsening vasogenic edema and mass effect are the hallmarks of recurrent
disease [1]. However, differentiation of treatment related necrosis from
recurrent neoplasm is often difficult with conventional MRI (cMRI) because both
entities can share the above mentioned features [2]. In this study, we evaluated
the usefulness for glioma recurrence grade increase detection of a
multiparametric MRI for combined exanimation of oxygen metabolism and microvessel
architecture.
Methods
Forty-one consecutive patients with suspected recurrent
glioma (7 WHO°II, 9 WHO°III, 25 glioblastoma) and one patient (glioblastoma
WHO°IV) during the first three cycles of antiangiogenic therapy (Avastin) were included in
this study. The patient under antiangiogenic therapy received one
baseline (one day before Avastin onset) and two follow-up (after the 1st
and 3rd cycle) MRI examinations. Vascular
architecture mapping (VAM) [3,4] and
multiparametric quantitative BOLD (mp-qBOLD) [5] were performed as part of the
routine MRI protocol at 3 Tesla (Trio, Siemens). For VAM a dual contrast agent
injections approach was used to obtain GE- and SE-EPI DSC perfusion MRI data [6].
To prevent timing differences between the two DSC examinations, a peripheral
pulse unit (PPU) which was used to monitor heart rate and cardiac cycle.
Special attention was paid to perform the two injections at the same heart rate
and exactly at the same phase of the cardiac cycle. For mp-qBOLD additional
performed T2*- and T2-mapping sequences were performed. Custom-made in-house MatLab
software was used for VAM and mp-qBOLD data postprocessing and compromised the
following 5 main steps: 1)
calculation of CBV and CBF maps from GE-EPI DSC data; 2) calculation of T2* and T2 maps; 3) calculation of maps of the oxygen metabolism MRI biomarkers
oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO
2);
4) calculation of
ΔR
2,GE versus
(ΔR
2,SE)
3/2 diagrams
(vascular hysteresis loops, VHLs) from GE- and SE-EPI DSC data;
and 5) calculation of maps of the vascular architecture
MRI biomarkers microvessel radius (R
U), density (N
U)
[7], and type indicator (MTI). cMRI was diagnosed by two experienced
radiologists in consensus.
Results
Form the seven patients with a suspected recurrent
low-grade glioma (LGG, WHO°II), two patients were diagnosed as recurrent LGG with
dedifferentiation based on cMRI (Figs.
1A, B, and E), which was in
agreement with the findings from oxygen metabolism: the areas with suspected
recurrent LGG showed increased OEF values, whereas in areas with suspected
dedifferentiation OEF values were decreased and CMRO
2 values were
decreased (Figs. 1C and D). For the remaining five LGG
patients no indication for recurrence of the lesion were found on cMRI (Figs. 2A, B, and E), but four patients (57 % of the initial LGG patients) showed significant
increased OEF values in the vicinity of the previous location of the lesions (Fig. 1C). Form the seven patients with
a suspected recurrent glioma WHO°III, three patients were diagnosed as
recurrent glioma based on cMRI, which was in agreement with the findings from oxygen
metabolism and microvessel architecture: increased values for CMRO
2,
N
U, and MTI within the suspicious regions. For the remaining six
patients no indication for recurrence of the lesion were found on cMRI (Figs. 3A, B, and E), but two patients (22 %) showed significant increased CMRO
2,
N
U, and MTI values in the vicinity of the previous lesion locations (Figs. 3D, G and H). Form the 25 patients with a suspected recurrent glioblastoma,
12 patients were diagnosed as recurrent glioblastoma based on cMRI, which was in
agreement with the findings from oxygen metabolism and microvessel
architecture: increased values for CMRO
2, R
U, N
U,
and MTI within the suspicious regions. For the remaining 13 patients no
indication for recurrence of the lesion were found on cMRI (Figs. 4A, B, and E), but eight patients (32 %) showed significant increased CMRO
2,
NU, and MTI values in the vicinity of the previous lesion locations (Figs. 4D, F, G and H). Finally, the follow-up examinations of the patient with a
recurrent glioblastoma under anti-angiogenic therapy showed no reliable signs
for therapy-induced changes CE T1w and CBV, but a moderate decrease in edema on
FLAIR. However, MR imaging biomarkers for oxygen metabolism and microvascular
architecture demonstrated changes in tumor physiology during anti-angiogenic
therapy. (Fig. 5)
Conclusions
Combined assessment of tumor oxygen metabolism and
angiogenesis provide insight into tumor biology and thus may be beneficial for follow-up
and therapy monitoring in glioma patients. However, investigations in more
well-defined patient populations and histological validations are necessary.
Acknowledgements
No acknowledgement found.References
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