Dosimetry of [Pb]VMT01, a MC1R-Targeted Alpha Therapeutic Compound, and Effect of Free Tl on Tissue Absorbed Doses.

[Pb]VMT01 is a melanocortin 1 receptor (MC1R) targeted theranostic ligand in clinical development for alpha particle therapy for melanoma. Pb has an elementally matched gamma-emitting isotope Pb; thus, [Pb]VMT01 can be used as an imaging surrogate for [Pb]VMT01. [Pb]VMT01 human serum stability studies have demonstrated retention of the Bi daughter within the chelator following beta emission of parent Pb.

The Expansion of Heterotopic Bone in Fibrodysplasia Ossificans Progressiva Is Activin A-Dependent.

Fibrodysplasia ossificans progressiva (FOP) is a rare autosomal dominant disorder that is characterized by episodic yet cumulative heterotopic ossification (HO) in skeletal muscles, tendons, and ligaments over a patient's lifetime. FOP is caused by missense mutations in the type I bone morphogenetic protein (BMP) receptor ACVR1. We have determined that the formation of heterotopic bone in FOP requires activation of mutant ACVR1 by Activin A, in part by showing that prophylactic inhibition of Activin A blocks HO in a mouse model of FOP.

Design of a dual-resolution collimator for preclinical cardiac SPECT with a stationary triple-detector system.

Purpose: One approach to preclinical single-photon emission computed tomography (SPECT) imaging that provides both high resolution and high sensitivity is based on imaging a mouse inside a collimating tube; many magnified pinhole projection images from a small target region, e.g., the heart, can be recorded simultaneously on multiple detectors with little multiplexing since each pinhole aperture's opening angle is restricted to view mostly the target organ.

Reconstruction of multiple-pinhole micro-SPECT data using origin ensembles.

Purpose: The authors are currently developing a dual-resolution multiple-pinhole microSPECT imaging system based on three large NaI(Tl) gamma cameras. Two multiple-pinhole tungsten collimator tubes will be used sequentially for whole-body "scout" imaging of a mouse, followed by high-resolution (hi-res) imaging of an organ of interest, such as the heart or brain. Ideally, the whole-body image will be reconstructed in real time such that data need only be acquired until the area of interest can be visualized well-enough to determine positioning for the hi-res scan.

Introduction of a novel ultrahigh sensitivity collimator for brain SPECT imaging.

Purpose: Noise levels of brain SPECT images are highest in central regions, due to preferential attenuation of photons emitted from deep structures. To address this problem, the authors have designed a novel collimator for brain SPECT imaging that yields greatly increased sensitivity near the center of the brain without loss of resolution. This hybrid collimator consisted of ultrashort cone-beam holes in the central regions and slant-holes in the periphery (USCB).

Dose reduction in half-time myocardial perfusion SPECT-CT with multifocal collimation.

Background: Recent technological advances in myocardial perfusion imaging may warrant the use of lower injected activity. We evaluated whether quantitative measures of stress myocardial perfusion defects using Tc-99m sestamibi and low-energy high-resolution (LEHR) collimators are equivalent to lower dose SPECT-CT with cardiac multifocal collimators and software (IQ·SPECT).

Methods: 93 patients underwent one-day rest-stress gated SPECT-CT.