Effects of three different doses of a bolus injection of gadodiamide: assessment of regional cerebral blood volume maps in a blinded reader study

Abstract

Background and purpose: Reconstruction of first-pass bolus information to derive regional cerebral blood volume (rCBV) maps is commonly performed in many centers; however, various protocols with different doses of paramagnetic contrast injections have been reported. We evaluated the dose dependency of rCBV maps in a brain tumor population by using three different doses of gadodiamide injection to evaluate their diagnostic accuracy in blinded reader sessions.

Methods: Eighty-three patients with intraaxial brain tumors (72 gliomas) were studied at three centers and randomized to receive a bolus injection of 0.1, 0.2, or 0.3 mmol/kg per body weight of gadodiamide. rCBV maps were generated from T2*-weighted gradient-echo echoplanar sequences at 1.5 T. Data processing was performed according to the indicator dilution theory.

Results: The mean contrast-to-noise ratio (CNR) was significantly different between gadodiamide doses of 0.1 and 0.2 mmol/kg (CNR = 8.7 and 15.7) and between 0.1 and 0.3 mmol/kg (CNR = 17.7). No significant difference was found between doses of 0.2 and 0.3 mmol/kg. Sensitivity for the differentiation of benign and malignant brain tumors was 80%, 95%, and 91%, and specificity was 45%, 54%, and 43% by blinded readings at 0.1, 0.2, and 0.3 mmol/ kg, respectively, as compared with histologic findings. Nonblinded readings had a sensitivity of 83%, 100%, and 90% and a specificity of 82%, 100%, and 73% at 0.1, 0.2, and 0.3 mmol/kg, respectively.

Conclusion: A dose of 0.2 mmol/kg of gadodiamide is recommended for reconstruction of rCBV maps if data are acquired with the T2*-weighted protocol described.

fig 1.

Tumor grade versus dose (given for the three dose groups: 0.1, 0.2, and 0.3 mmol/kg body weight (bw) (n = 72)

fig 2.

Low-grade tumor: injected dose, 0.1 mmol/kg. A, Proton density–weighted image (2300/20/1) in a 38-year-old woman with a homogeneous lesion in the left parietal cortex. The tumor (arrow) was proved histologically to be a grade II glioma according to WHO criteria. B, Contrast-enhanced T1-weighted image (530/20/1) shows no apparent enhancement in the tumor (arrow). C, rCBV map confirms a low-grade lesion by exhibiting values below that of normal gray matter (arrows). However, at this dose the contrast within the rCBV maps was rated as limited.

fig 3.

Low-grade tumor: injected dose, 0.2 mmol/kg. A, T2-weighted image (2300/85/1) in a 31-year-old man shows a mass in the right frontal cortex with an appearance not unlike that of a low-grade intraaxial brain tumor. B, Contrast-enhanced T1-weighted image (530/20/1) shows a tumor without contrast enhancement (arrow). C, rCBV map shows low values in the tumor (arrows), confirmed to be a WHO grade II glioma. The contrast effect and the image quality of the rCBV map were graded superior to that in figure 2.

fig 4.

Low-grade tumor: injected dose, 0.3 mmol/kg. A, T2-weighted image (2300/85/1) in a 22-year-old woman shows a large mass in the right insular region (white arrow). The dark dots are flow voids from the branches of the middle cerebral artery (black arrow). B, rCBV map shows low values in the tumor (arrow), even below those of adjacent white matter. The lesion was confirmed to be a WHO grade II glioma.

fig 5.

High-grade tumor: injected dose, 0.1 mmol/kg. A, Contrast-enhanced T1-weighted image (530/20/1) in a 44-year-old man with a mass in the left central region shows irregular contrast enhancement (arrow). B, rCBV map shows elevation of the rCBV of the tumor (arrow) but with little contrast. The lesion was confirmed to be a WHO grade VI glioma.

fig 6.

High-grade tumor: injected dose, 0.2 mmol/kg. A, Contrast-enhanced T1-weighted image (530/20/1) in a 50-year-old man examined 4 month after initial surgery for a WHO grade VI glioma suggests recurrent tumor (arrow). B, rCBV map shows elevated values of the tumor in a small rim (arrow), indicative of only a small portion of active tumor with high rCBV.

fig 7.

High-grade tumor: injected dose, 0.3 mmol/kg. A, Contrast-enhanced T1-weighted image (530/20/1) shows a large enhancing lesion in a 60-year-old woman. Mass effect and poorly defined margins are also present. B, rCBV map shows increased values in almost the entire tumor, except for a necrotic region (arrow) in this WHO grade VI glioma.