[Monitoring of irradiated brain metastases using MR perfusion imaging and 1H MR spectroscopy].
OBJECTIVE
In follow-up examinations of irradiated brain metastases conventional contrast-enhanced morphological MR imaging is often unable to distinguish between transient radiation effects, radionecrosis,and tumor recurrence. To evaluate changes of relative cerebral blood flow (rCBF) in irradiated brain metastases arterial spin-labeling techniques (ASL) were applied and compared to the outcome of (1)H MR spectroscopy and spectroscopic imaging ((1)H MRS, SI).


METHODS
In 2 patients follow-up examinations of irradiated brain metastases were performed on a 1.5-T tomograph (average single dose: 20 Gy/80% isodose). Relative CBF values of gray matter (GM), white matter (WM),and metastases (Met) were measured by means of the ASL techniques ITS-FAIR and Q2TIPS. (1)H MRS was performed with PRESS 1500/135.


RESULTS
In both patients with initially hyperperfused metastases (Met/GM >1) the reduction of rCBF after stereotactic radiosurgery indicated response to treatment--even if the contrast-enhancing region increased--while increasing rCBF values indicated tumor progression. The findings were confirmed by (1)H MRS, SI and subsequent follow-up.


CONCLUSIONS
The ASL techniques ITS-FAIR and Q2TIPS are able to monitor changes of rCBF in irradiated brain metastases. The two cases imply a possible role for ASL-MR perfusion imaging and (1)H MR spectroscopy in differentiating radiation effects from tumor progression.
Weber
Marc-André
MA
Forschungsschwerpunkt Radiologische Diagnostik und Therapie, Abteilung Onkologisches Diagnostik und Therapie, Deutsches Krebsforschungszentrum Heidelberg. m.a.weber@dkfz.de
Lichy
M P
MP
Thilmann
C
C
Günther
M
M
Bachert
P
P
Maudsley
A A
AA
Delorme
S
S
Schad
L R
LR
Debus
J
J
Schlemmer
H-P
HP
D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001921:Brain / Q000098:blood supply* / Q000601:surgery; D001932:Brain Neoplasms / Q000098:blood supply / Q000556:secondary* / Q000601:surgery*; D002289:Carcinoma, Non-Small-Cell Lung / Q000098:blood supply / Q000556:secondary / Q000601:surgery; D003937:Diagnosis, Differential; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000098:blood supply / Q000601:surgery; D018810:Magnetic Resonance Angiography / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008545:Melanoma / Q000098:blood supply / Q000556:secondary / Q000601:surgery; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000503:physiopathology; D011522:Protons; D016634:Radiosurgery; D012039:Regional Blood Flow / Q000502:physiology; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000098:blood supply / Q000601:surgery
D011522:Protons