Comparison of perfusion harmonic imaging and perfusion mr imaging for the assessment of microvascular characteristics in brain tumors.
OBJECTIVE
The purpose of this study was to evaluate the potential of perfusion harmonic imaging (pHI) for assessing microvascular characteristics of brain tumors and to compare this ultrasound technique to perfusion MRI (pMRI).


METHODS
Twenty-five patients with brain tumors underwent transtemporal pHI and fourteen of these patients underwent additional pMRI. Time-intensity curves of two different regions of interest (ROIs; (1) enhancing tumor; (2) healthy brain) were calculated off-line, and the following parameters were compared between the two ROIs and the two methodologies: time-to-peak intensity (TTP [sec]), the ratios of the peak intensities (PI ratio), the ratios of the positive slope gradient (PG ratio) and the ratios of the area under the curve (AUC ratio). p < 0.05 was considered statistically significant.


RESULTS
Four of 25 patients were excluded due to bone window insufficiency or unfavorable tumor location. Focal abnormal echogenicity was detected in native B-mode in 86 % of the patients. Contrast agent administration led to remarkable echo enhancement in the tumor in all patients with corresponding time-intensity curves. Both pHI and pMRI showed significant differences with respect to the mean PI, PG and AUC (pHI: p < 0.001 / < 0.001 / < 0.001; pMRI: p < 0.05 / < 0.05 / < 0.001) when comparing tumor to healthy brain. The TTP was not significantly different in tumor and brain tissue. Comparison of pHI and pMRI data did not show any significant differences for three of four parameter ratios between both methodologies.


CONCLUSIONS
PHI provides a new technique for assessing microvascular characteristics of brain tumors reflecting their abnormal perfusion. Overall comparison of this methodology to pMRI demonstrated encouraging results. Further studies should address the clinical potential of pHI especially in view of microvascular response to anti-angiogenic treatment.
D000328:Adult; D000368:Aged; D001254:Astrocytoma / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology; D001932:Brain Neoplasms / Q000098:blood supply* / Q000000981:diagnostic imaging* / Q000473:pathology; D002455:Cell Division; D005260:Female; D005910:Glioma / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008579:Meningioma / Q000098:blood supply / Q000000981:diagnostic imaging / Q000473:pathology; D008833:Microcirculation; D008875:Middle Aged; D014463:Ultrasonography / Q000379:methods