Patients referred for MRI of the central nervous system with contrast were enrolled in two clinical trials that evaluated the visualization characteristics of lesions. In both studies, patients underwent a baseline, pre-contrast MRI prior to administration of gadobutrol injection at a dose of 0.1 mmol/kg, followed by a post-contrast MRI. In Study A, patients also underwent an MRI before and after the administration of gadoteridol. The studies were designed to demonstrate superiority of gadobutrol injection MRI to non-contrast MRI for lesion visualization. For both studies, pre-contrast and pre-plus-post contrast images (paired images) were independently evaluated by three readers for contrast enhancement and border delineation using a scale of 1 to 4, and for internal morphology using a scale of 1 to 3 (Table 5). Lesion counting was also performed to demonstrate non-inferiority of paired gadobutrol injection image sets to pre-contrast MRI. Readers were blinded to clinical information.

Efficacy was determined in 657 subjects. The average age was 49 years (range 18 to 85 years) and 42% were male. The ethnic representations were 39% Caucasian, 4% Black, 16% Hispanic, 38% Asian, and 3% of other ethnic groups.

Table 6 shows a comparison of visualization results between paired images and pre-contrast images. Gadobutrol injection provided a statistically significant improvement for each of the three lesion visualization parameters when averaged across three independent readers for each study.

Performances of gadobutrol and gadoteridol for visualization parameters were similar. Regarding the number of lesions detected, Study B met the prespecified noninferiority margin of -0.35 for paired read versus pre-contrast read while in Study A, gadobutrol and gadoteridol did not.

For the visualization endpoints contrast enhancement, border delineation, and internal morphology, the percentage of patients scoring higher for paired images compared to pre-contrast images ranged from 93% to 99% for Study A, and 95% to 97% for Study B. For both studies, the mean number of lesions detected on paired images exceeded that of the pre-contrast images; 37% for Study A and 24% for Study B. There were 29% and 11% of subjects in which the pre-contrast images detected more lesions for Study A and Study B, respectively.

The percentage of patients whose average reader mean score changed by ≤ 0, up to 1, up to 2, and ≥ 2 scoring categories presented in Table 5 is shown in Table 7. The categorical improvement of (≤ 0) represents higher (< 0) or identical (= 0) scores for the pre-contrast read, the categories with scores > 0 represent the magnitude of improvement seen for the paired read.

For both studies, the improvement of visualization endpoints in paired gadobutrol injection images compared to pre-contrast images resulted in improved assessment of normal and abnormal CNS anatomy.

###  Pediatric Patients

Two studies in 44 pediatric patients age younger than 2 years and 135 pediatric patients age 2 to less than 18 years with CNS and non-CNS lesions supported extrapolation of adult CNS efficacy findings. For example, comparing pre vs paired pre- and post-contrast images, investigators selected the best of four descriptors under the heading, “Visualization of lesion-internal morphology (lesion characterization) or homogeneity of vessel enhancement” for 27/44 (62% = pre) vs 43/44 (98% = paired) MR images from patients age 0 to less than 2 years and 106/135 (78% = pre) vs 108/135 (80% = paired) MR images from patients age 2 to less than 18 years.