The identification of cerebral volume changes in treated growth hormone-deficient adults using serial 3D MR image processing

Purpose: A pilot study to detect volume changes of cerebral structures in g rowth hormone (GH)-deficient adults treated with GH using serial 3D MR imag e processing and to assess need for segmentation prior to registration was conducted. Method: Volume MR scans of the brain were obtained in five patients and six control subjects. Patients were scanned before and after 3 and 6 months of therapy. Control subjects were scanned at the same intervals. A phantom wa s used to quantify scaling errors. Second and third volumes were aligned wi th the baseline by maximizing normalized mutual information and transformed using sine interpolation. Registration was performed with and without brai n segmentation and correction of scaling errors. Each registered, transform ed image had the original subtracted, generating a difference image. Struct ural change and effects of segmentation and scaling error correction were a ssessed on original and difference images. The radiologists' ability to det ect volume change was also assessed. Results: Compared with control subjects, GH-treated subjects had an increas e in cerebral volume and reduction in ventricular volume (p = 0.91 x 10(-3) ). Scale correction and segmentation made no difference (p = 1 and p = 0.87 3). Structural changes were identified in the difference images but not in the original (p = 0.136). The radiologists detected changes >200 mu m Conclusion: GH treatment in deficient patients results in cerebral volume c hanges detectable by registration and subtraction of serial MR studies but not by standard assessment of images. This registration method did not requ ire prior segmentation.