The Role of preload and leakage correction in gadolinium-based cerebral blood volume estimation determined by comparison with MION as a criterion standard.
OBJECTIVE
Contrast extravasation in DSC-MRI potentiates inaccurate and imprecise estimates of glioma rCBV. We tested assertions that preload and postprocessing algorithms minimize this error by comparing Gd-rCBV using permutations of these 2 techniques with criterion standard rCBV using MION, an intravascular agent.


METHODS
We imaged 7 Fisher rats with 9L gliosarcomas, by using 3T gradient-echo DSC-MRI with MION (2.0 mg Fe/kg) and staged injection of Gd-diethylene triamine pentaacetic acid: a 0.1-mmol/kg bolus provided no preload (P-) data and served as preload (P+) for a subsequent 0.2-mmol/kg bolus. We computed MION-rCBV (steady-state ΔR2*, tumor versus normal brain) and Gd-rCBV ΔR2* [t] integration) without (C-) and with (C+) postprocessing correction, thereby testing 4 correction permutations: P-C-, P-C+, P+C-, and P+C+. We tested whether each permutation reduced bias and variance of the Gd/MION rCBV differences by using generalized estimating equations and Fmax statistics (P < .05 significant).


RESULTS
Gd-rCBV progressively better approximated MION-rCBV with increasing leakage correction. There was no statistically significant bias for the mean percentage deviation of Gd-rCBV from MION-rCBV for any correction permutation, but there was significantly reduced variance by using P+C- (22-fold), P-C+ (32-fold), and P+C+ (267-fold) compared with P-C-. P+C+ provided significant additional variance reduction compared with P+C- (12-fold) and P-C+ (8-fold). Linear regression of Gd-rCBV versus MION-rCBV revealed P+C+ to have the closest slope and intercept compared with the ideal, substantially better than P+C-.


CONCLUSIONS
Preload and postprocessing correction significantly reduced the variance of Gd-rCBV estimates, and bias reduction approached significance. Postprocessing correction provide significant benefit beyond preload alone.
Department of Diagnostic Imaging, Rhode Island Hospital, Providence, RI 02903, USA. jboxerman@lifespan.org
J L
JL
Boxerman
D E
DE
Prah
E S
ES
Paulson
J T
JT
Machan
D
D
Bedekar
K M
KM
Schmainda
D000818:Animals; D001810:Blood Volume; D001811:Blood Volume Determination / Q000379:methods*; D001932:Brain Neoplasms / Q000473:pathology / Q000503:physiopathology*; D045744:Cell Line, Tumor; D003287:Contrast Media; D019786:Gadolinium DTPA; D018316:Gliosarcoma / Q000473:pathology / Q000503:physiopathology*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D051381:Rats; D011916:Rats, Inbred F344; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA