title: Visual pathway impairment by pituitary adenomas: quantitative diagnostics by diffusion tensor imaging.
abstract: OBJECTIVE Despite ample experience in surgical treatment of pituitary adenomas, little is known about objective indices that may reveal risk of visual impairment caused by tumor growth that leads to compression of the anterior visual pathways. This study aimed to explore diffusion tensor imaging (DTI) as a means for objective assessment of injury to the anterior visual pathways caused by pituitary adenomas. METHODS Twenty-three patients with pituitary adenomas, scheduled for transsphenoidal tumor resection, and 20 healthy control subjects were included in the study. A minimum suprasellar tumor extension of Grade 2-4, according to the SIPAP (suprasellar, infrasellar, parasellar, anterior, and posterior) scale, was required for inclusion. Neuroophthalmological examinations, conventional MRI, and DTI were completed in all subjects and were repeated 6 months after surgery. Quantitative assessment of chiasmal lift, visual field defect (VFD), and DTI parameters from the optic tracts was performed. Linear correlations, group comparisons, and prediction models were done in controls and patients. RESULTS Both the degree of VFD and chiasmal lift were significantly correlated with the radial diffusivity (r = 0.55, p < 0.05 and r = 0.48, p < 0.05, respectively) and the fractional anisotropy (r = -0.58, p < 0.05 and r = -0.47, p < 0.05, respectively) but not with the axial diffusivity. The axial diffusivity differed significantly between controls and patients with VFD, both before and after surgery (p < 0.05); however, no difference was found between patients with and without VFD. Based on the axial diffusivity and fractional anisotropy, a prediction model classified all patients with VFD correctly (sensitivity 1.0), 9 of 12 patients without VFD correctly (sensitivity 0.75), and 17 of 20 controls as controls (specificity 0.85). CONCLUSIONS DTI could detect pathology and degree of injury in the anterior visual pathways that were compressed by pituitary adenomas. The correlation between radial diffusivity and visual impairment may reflect a gradual demyelination in the visual pathways caused by an increased tumor effect. The low level of axial diffusivity found in the patient group may represent early atrophy in the visual pathways, detectable on DTI but not by conventional methods. DTI may provide objective data, detect early signs of injury, and be an additional diagnostic tool for determining indication for surgery in cases of pituitary adenomas.
authors.affiliation: Department of Clinical Neuroscience and Rehabilitation and.|Ear, Nose and Throat Clinic.
authors.forename: Ylva
authors.initials: Y
authors.lastname: Lilja
authors.affiliation: Department of Radiation Physics and.|Department of Medical Physics and Biomedical Engineering, and.
authors.forename: Oscar
authors.initials: O
authors.lastname: Gustafsson
authors.affiliation: Department of Radiation Physics and.|Department of Medical Physics and Biomedical Engineering, and.
authors.forename: Maria
authors.initials: M
authors.lastname: Ljungberg
authors.affiliation: Department of Radiation Physics and.|Department of Medical Physics and Biomedical Engineering, and.
authors.forename: Göran
authors.initials: G
authors.lastname: Starck
authors.affiliation: Department of Ophthalmology, Institute of Neuroscience and Physiology.
authors.forename: Bertil
authors.initials: B
authors.lastname: Lindblom
authors.affiliation: Department of Clinical Neuroscience and Rehabilitation and.|Department of Neurosurgery, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Skoglund
authors.affiliation: Department of Otorhinolaryngology, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg; and.|Ear, Nose and Throat Clinic.
authors.forename: Henrik
authors.initials: H
authors.lastname: Bergquist
authors.affiliation: Department of Clinical Neuroscience and Rehabilitation and.|Department of Neurosurgery, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Karl-Erik
authors.initials: KE
authors.lastname: Jakobsson
authors.affiliation: Department of Clinical Neuroscience and Rehabilitation and.|Department of Neurosurgery, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Nilsson
mesh_terms: D000236:Adenoma; D016880:Anisotropy; D056324:Diffusion Tensor Imaging; D006801:Humans; D010911:Pituitary Neoplasms; D014795:Visual Pathways; D066127:White Matter
keywords: AD = axial diffusivity; DTI = diffusion tensor imaging; FA = fractional anisotropy; HRP = high-pass resolution perimetry; MD = mean diffusivity; OT = optic tract; RD = radial diffusivity; ROI = region of interest; SIPAP = suprasellar, infrasellar, parasellar, anterior, and posterior; VFD = visual field defect; anterior visual pathways; diffusion tensor imaging; pituitary adenoma; pituitary surgery; quantitative diagnostics, diagnostic technique; visual impairment