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AJNR - American Journal of Neuroradiology

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Qualitative versus Quantitative Assessment of Cerebrovascular Reactivity to Acetazolamide Using iodine-123-N-Isopropyl-p-Iodoamphetamine SPECT in Patients with Unilateral Major Cerebral Artery Occlusive Disease

Kuniaki Ogasawara^a, Taku Okuguchi^a, Masayuki Sasoh^a, Masakazu Kobayashi^a, Hirotsugu Yukawa^a, Kazunori Terasaki^a, Takashi Inoue^a and Akira Ogawa^a

^a From the Department of Neurosurgery and the Cyclotron Research Center, Iwate Medical University, Morioka, Japan

View larger version (103K): [in a new window]   FIG 1. ROIs in image sections standardized and summed by using 3D-SSPs.

View larger version (28K): [in a new window]   FIG 2. Comparisons of qualitative rCVR with quantitative rCVR (%Hem) calculated by using the IMP autoradiographic method. Significant correlation was observed between these two values. A plot of the relationship between these two values revealed four groups of results: 1) those with reduced rCVR (true-positive), 2) those in which only the quantitative method identified reduced rCVR (false-negative), 3) those without reduced rCVR (true-negative), and 4) those considered reduced rCVR only by the qualitative method (false-positive). Dashed horizontal and vertical lines denote the mean - 2 SDs of the rCVR values obtained in healthy volunteers by using the quantitative method or the qualitative method. A, AIHem change. B, FIHem-Cbl change.

View larger version (25K): [in a new window]   FIG 3. Example of a false-positive result. The same color scale is used to display quantitative rCBF images calculated by using the IMP autoradiographic method at resting state and with the acetazolamide challenge. This patient had a symptomatic occluded ICA on the right side. After the administration of acetazolamide, the patient’s rCBF in the MCA territory increased by 10.3 mL/100 g/min on the right side and by 26.4 mL/100 g/min on the contralateral side. This increase was asymmetrical, with the qualitative assessment defining rCVR as reduced (AIHem change = -28.3), although %Hem on the occluded side, as determined quantitatively, showed a normal flow response of 31.0%.

View larger version (25K): [in a new window]   FIG 4. Example of a false-negative result. The same color scale is used to display quantitative rCBF images calculated by using the IMP autoradiographic method at the resting state and with the acetazolamide challenge. This patient had a symptomatic occluded ICA on the left side. After the administration of acetazolamide, the patient’s blood flow in the MCA territory increased only by 2.1 mL/100 g/min on the left side (%Hem = 6.0%) and by 3.1 mL/100 g/min on the contralateral side (%Hem = 8.9%). As asymmetry was absent, the use of rCBF ratios (AIHem change = -2.7) would fail to identify a bilateral reduction of flow response to acetazolamide.

View larger version (21K): [in a new window]   FIG 5. ROC curves used to determine the diagnostic accuracy of the AIHem change and the FIHem-Cbl change.