U-SPECT-I: A Novel System for Submillimeter-Resolution Tomography with Radiolabeled Molecules in Mice

Illustration of highly focusing pinhole geometry of U-SPECT-I. (A) Cross section through 1 of 5 rings with pinholes. Lines emerging from central circle mark triangular cross sections of beams in which emitted γ-quanta can travel from animal toward detector. Pinholes in all rings focus on center to maximize detection yield. Lead cylinder with square holes shown in gray is placed around tungsten cylinder with pinholes to prevent projection overlap. (B) Radiation intensity on 1 of 3 detectors when a bottle with a ^99mTc solution is imaged. Image demonstrates how the large detector is divided into a large number of small subcameras.

Demonstration of high sensitivity of U-SPECT-I. Shown are sensitivity profiles lying along mutually orthogonal lines that cross the center of field of view, obtained with a scanning point source: along x-axis (A), along y-axis (B), and along transaxial axis (z-axis) (C).

Demonstration of submillimeter resolution of U-SPECT-I images. (A) Photograph of miniature acrylic resolution phantom with capillaries used as test object. (B) Reconstructed cross-sectional image, with a slice thickness of 0.5 mm, of the phantom shown in A. Half-millimeter capillaries are clearly separated on image.

Mutual perpendicular cross sections through submillimeter-resolution 3-dimensional myocardial perfusion image volume of living mouse (named Animal Co-Image of the Year at the annual meeting of the Society of Nuclear Medicine, Philadelphia, 2004). Image data were acquired during 30 min, starting 30 min after administration of 222 MBq (6 mCi) of ^99mTc-tetrofosmin. On left is a short-axis slice showing myocardial perfusion in right ventricular (RV) and left ventricular (LV) walls. Perfusion in anterior papillary muscle (arrow) can be distinguished from other parts of left ventricular wall. At top right is a vertical long-axis slice; at bottom right, a horizontal long-axis slice.