- Starting at the most anterior slice where the lateral ventricles are visible, the gray-CSF and white-CSF tissue boundaries of the lateral ventricles are followed with a mouse-driven cursor. The signal intensity of T1-weighted scans may be enhanced, although should be consistent between subjects and preferably set to a standard. The lateral ventricles are divided into superior, posterior and inferior horns and should be contoured on coronal brain slices while referencing orthogonal planes to clarify neuroanatomical boundaries if necessary. CSF/tissue interfaces are digitized separately and include the superior; lateral, and medial CSF/tissue interfaces for the superior horn. Inferior and posterior horn CSF/tissue surfaces include only lateral and medial surfaces. The boundaries determining these surfaces are shown in color in (Fig. 1).
- The direction for tracing the lateral ventricle boundaries must be consistent. That is, the each segment should start at the same neuroanatomical point for each brain scan. For the superior horn, the superior segment should start medially in each hemisphere and traced laterally. The superior horn medial segment should start at the same point as the superior segment and be traced ventrally on coronal sections. The lateral segment of the superior horn should be traced beginning at the termination point of the medial segment. The medial and lateral segments of the posterior horn should continue in the directions of the medial and lateral segments of the superior horn. For the inferior horn, superior and inferior segments are traced from medially to laterally. It is not necessary for these rules be followed for individual protocols. It is imperative that the same landmarks are used for each subject and that the contours are always traced in the same direction (Fig. 2). Figure 3 shows surface mesh models of the lateral ventricle superior, inferior and posterior horns.
- Choroid plexus is excluded in lateral ventricle traces even if there is no visible separation between choroid plexus and the floor of the ventricle.
Summary of Lateral Ventricle Delineation Guidelines
|Superior Horn||lateral, medial and superior||Anterior: Frontal lobes where first discernable.||Posterior: First level where superior and inferior horns join (atrium).|
|Posterior Horn||lateral and medial||Anterior: Superior horn termination point.||Posterior: Last appearance in occipital lobe.|
|Inferior Horn||superior, inferior||Anterior: First appearance in temporal lobes.||Posterior: Same level as superior horn termination point.|